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SDLRC - Scientific Articles all years by Author - Pe-Pn


The Sheahan Diamond Literature Reference Compilation
The Sheahan Diamond Literature Reference Compilation is compiled by Patricia Sheahan who publishes on a monthly basis a list of new scientific articles related to diamonds as well as media coverage and corporate announcementscalled the Sheahan Diamond Literature Service that is distributed as a free pdf to a list of followers. Pat has kindly agreed to allow her work to be made available as an online digital resource at Kaiser Research Online so that a broader community interested in diamonds and related geology can benefit. The references are for personal use information purposes only; when available a link is provided to an online location where the full article can be accessed or purchased directly. Reproduction of this compilation in part or in whole without permission from the Sheahan Diamond Literature Service is strictly prohibited. Return to Diamond Resource Center
Sheahan Diamond Literature Reference Compilation - Scientific Articles by Author for all years
A-An Ao+ B-Bd Be-Bk Bl-Bq Br+ C-Cg Ch-Ck Cl+ D-Dd De-Dn Do+ E F-Fn Fo+ G-Gh Gi-Gq Gr+ H-Hd He-Hn Ho+ I J K-Kg Kh-Kn Ko-Kq Kr+ L-Lh
Li+ M-Maq Mar-Mc Md-Mn Mo+ N O P-Pd Pe-Pn Po+ Q R-Rh Ri-Rn Ro+ S-Sd Se-Sh Si-Sm Sn-Ss St+ T-Th Ti+ U V W-Wg Wh+ X Y Z
Sheahan Diamond Literature Reference Compilation - Media/Corporate References by Name for all years
A B C D-Diam Diamonds Diamr+ E F G H I J K L M N O P Q R S T U V W X Y Z
Tips for Users
Posted/Published Reference CodesThe SDLRC provides 3 types of references identified in the reference code. DS for scientific article, DM for a media article, and DC for a corporate announcement. Consider DS0512-0001. The DS stands for "diamond scientific". 05 stands for 2005, the year the reference was posted. 12 represents the month the reference was posted. For all years prior to 2015 the default month is 12. -0001 is the reference's identifier and it does not mean anything. The number below the refence code, ie 2015, is the year the article was published. Note that the posted year may sometimes be later than the published year.
Sort OrderReferences are sorted by the "author" name and when the reference was posted to the compilation.
Most RecentIf the reference code is highlighted yellow, the reference was made available through the most recent monthly compilation of new literature. Use this to check out new references. When new references are posted, we make it our priority to track down an online link and obtain an abstract. With regard to older references, tracking down an abstract and an online link is a work in progress.
Link to external location of article: If the title has a link, it means we have found a location online where you can either retrieve the full article free, or purchase access to it. The Sheahan Diamond Literature Service is not a technical article procurement service; if you want a restricted article, you must deal directly with the vendor who controls the copyright to the article.
Searching this page for a specific term or authorIn your Firefox browser click Edit in the menu bar and then Find. In the Find box that shows up at the bottom of the web page enter your search term. Firefox will highlight all occurrences. This is particularly helpful when the author you are seeking was not the lead author by whom the compilation is sorted.
Sending or sharing a referenceThe left column (Posted/Published) has an embedded hyperlink for each reference. In Firefox, if you right click on it, you can obtain the link url for that reference's location within the page, which you can copy and paste into an email or any other document. You can also use the "share this link" option to tweet, facebook etc the link.
Author Index
A-An Ao+ B-Bd Be-Bk Bl-Bq Br+ C-Cg Ch-Ck Cl+ D-Dd De-Dn Do+ E F-Fn Fo+ G-Gh Gi-Gq Gr+ H-Hd He-Hn Ho+ I J K-Kg Kh-Kn Ko-Kq Kr+ L-Lh
Li+ M-Maq Mar-Mc Md-Mn Mo+ N O P-Pd Pe-Pn Po+ Q R-Rh Ri-Rn Ro+ S-Sd Se-Sh Si-Sm Sn-Ss St+ T-Th Ti+ U V W-Wg Wh+ X Y Z
Sheahan Diamond Literature Reference Compilation - Scientific Articles by Author for all years - Pe-Pn
Posted/
Published
AuthorTitleSourceRegionKeywords
DS202108-1304
2021
Peace, A.L.Peace, A.L.Beyond ' crumple zones': recent advances, application and future directions in deformable plate tectonic modeling.Geological Magazine, doi:10.1017/S0016756821000534 7p.Mantleplate tectonics

Abstract: The recent proliferation of deformable plate tectonic modelling techniques has provided a new direction in the study of plate tectonics with substantial implications for our understanding of plate deformation and past kinematics. Such models account for intraplate deformation, yet are highly variable in their inputs, capabilities and applications. The aim of this commentary is to review recent contributions to this topic, and to consider future directions and major omissions. Through this review it is apparent that the current published deformable models can be subdivided into those that as an input either: (1) solely use plate motions to drive deformation, or (2) require stretching or beta factor. Deformable models are resolving some outstanding issues with plate reconstructions, but major simplifications and modelling assumptions remain. Primarily, obtaining model constraints on the spatio-temporal evolution of deformation is an outstanding problem. Deformable plate models likely work best when the kinematics of smaller plates are included. However, questions remain regarding how to define such blocks, and their kinematic histories, whilst some work suggests that inclusion of such entities is negated through quantitative restorations.
DS1993-1134
1993
Peach, C.L.Nilsson, K., Peach, C.L.Sulfur speciation, oxidation state and sulfur concentration in backarcmagmasGeochimica et Cosmochimica Acta, Vol. 57, pp. 3807-3813GlobalSilicate melts, MORBS
DS1990-1163
1990
Peachpit PressPeachpit Press, Berkley CaliforniaWordPerfect: desktop publishing in stylePeachpit Press, Berkley California, 645pGlobalWill-Harris, D., Wordperfect
DS201610-1895
2016
Peacock, J.R.Peacock, J.R., Denton, K.M., Ponce, D.A.Magnetotelluric imaging of a carbonatite terrane in the southeast Mojave desert, California and Nevada.ASEG-PESA-AIG 2016 25th Geophysical Conference, abstract 5p.United States, California, NevadaCarbonatite

Abstract: The southeast Mojave Desert hosts one of the world’s largest rare earth element (REE) deposits at Mountain Pass, California. Although surface geology has been studied, a full understanding of the carbonatite and associated intrusive suite complex requires subsurface geophysical characterization. In this study, a combination of geophysical methods, including magnetotelluric (MT), magnetics, and gravity are used to create a two-dimensional (2D) geophysical model to a depth of about 10 km. An electrically conductive body is found 2-3 km below and west of the deposit that is associated with a magnetic high that could be connected to a deeper (10 km) conductive body related to possible intrusions or hydrothermal systems. The carbonatite body coincides with a steep magnetic gradient and a bench or terrace in the gravity data that may reflect relative lower-density intrusive rocks. Although carbonatite rocks are typically magnetic, the carbonatite rocks, associated intrusive suite, and host rocks in this area are essentially non-magnetic. Combined geophysical data indicate that the enriched REE deposit may be related to a regional extensive hydrothermal alteration event.
DS1990-1164
1990
Peacock, S.M.Peacock, S.M.Fluid processes in subduction zonesScience, Vol. 248, No. 4953, April 20, pp. 329-337GlobalMantle-crust, Tectonics
DS1991-1308
1991
Peacock, S.M.Peacock, S.M.Metamorphic geologyInternational Union of Geodesy and Geophysics, 20th. meeting held Vienna August, pp. 486-499GlobalMetamorphic geology, Overview -review paper
DS1991-1645
1991
Peacock, S.M.Spear, F.S., Peacock, S.M., Kohn, M.J., Florence, F.P., Menard, T.Computer programs for petrologic P-T-t path calculationsAmerican Mineralogist, Vol. 76, No. 11, 12 November-December pp. 2009-2012GlobalComputer, Program -petrologic P-T-t
DS1993-1202
1993
Peacock, S.M.Peacock, S.M.The importance of blueschist - eclogite dehydration reactions in subducting oceanic crustGeological Society of America Bulletin, Vol. 105, No. 5, May pp. 684-694Globalmetamorphism, Crust, Subduction
DS1993-1203
1993
Peacock, S.M.Peacock, S.M.Large scale hydration of the lithosphere above subducting slabsChemical Geology, Vol. 108, No. 1-4, August 5, pp. 49-60GlobalSubduction, Mantle, Tectonics
DS1993-1204
1993
Peacock, S.M.Peacock, S.M.Large scale hydration of the lithosphere above subducting slabsChemical Geology, Vol. 108, No. 1-4, August 5, pp. 49-60.MantleSubduction, Tectonics
DS1994-1345
1994
Peacock, S.M.Peacock, S.M., Rushmer, T., Thompson, A.B.Partial melting of subducting oceanic crustEarth and Planetary Science Letters, Vol. 121, No. 1/2, January pp. 227-244.MantleSubduction, Tectonics, Oceanic Crust
DS1994-1346
1994
Peacock, S.M.Peacock, S.M., Rushmer, T., Thompson, A.B.Partial melting of subducting oceanic crustEarth and Planetary Science Letters, Vol. 121, pp. 227-244MantleTectonics, Subduction
DS1995-1452
1995
Peacock, S.M.Peacock, S.M., Goodge, J.W.Eclogite facies metamorphism preserved in tectonic blocks from a lower crustal shear zone, TransantarcticLithos, Vol. 36, No. 1, Aug. 1, pp. 1-14.Antarcticametamorphism, Eclogite
DS1999-0537
1999
Peacock, S.M.Peacock, S.M., Hervig, R.L.Boron isotopic composition of subduction zone rocksChemical Geology, Vol. 160, No. 4, Sept. 2, pp. 281-90.MantleGeochronology, Subduction
DS1999-0538
1999
Peacock, S.M.Peacock, S.M., Hyndman, R.D.Hydrous minerals in the mantle wedge and the maximum depth of subduction thrust earthquakes.Geophysical Research. Lett., Vol. 26, No. 16, Aug. 15, pp. 2517-20.MantleSubduction, Mineralogy
DS2001-0894
2001
Peacock, S.M.Peacock, S.M.Are the lower planes of double seismic zones caused by serpentine dehydration in subducting oceanic mantle?Geology, Vol. 29, No. 4, Apr. pp.299-302.Mantlemetamorphism, Subduction
DS2002-0192
2002
Peacock, S.M.Bostock, M.G., Hyndman, R.D., Rondenay, S., Peacock, S.M.An inverted continental MOHO and serpentinization of the forearc mantleNature, No. 6888, May 3o, pp.536-7.MantleBoundary
DS2003-0614
2003
Peacock, S.M.Hyndman, R.D., Peacock, S.M.Serpentinization of the forearc mantleEarth and Planetary Science Letters, Vol. 212, 3/4, pp. 417-432.MantleMetasomatism
DS200412-0863
2003
Peacock, S.M.Hyndman, R.D., Peacock, S.M.Serpentinization of the forearc mantle.Earth and Planetary Science Letters, Vol. 212, 3/4, pp. 417-432.MantleMetasomatism
DS202009-1653
2020
Peacock, S.M.Peacock, S.M.Advances in the thermal and petrologic modeling of subduction zones.Geosphere, Vol. 16, 4, 17p. PdfMantlegeothermometry

Abstract: In the two decades since Subduction: Top to Bottom was published in 1996, improved analytical and numerical thermal-petrologic models of subduction zones have been constructed and evaluated against new seismological and geological observations. Advances in thermal modeling include a range of new approaches to incorporating shear (frictional, viscous) heating along the subduction interface and to simulating induced flow in the mantle wedge. Forearc heat-flux measurements constrain the apparent coefficient of friction (??) along the plate interface to
DS1989-0762
1989
Peacor, D.R.Kersting, A.B., Peacor, D.R., Arculus, R.J.STEM study of preserved diffusion gradients in lower crustal Upper Mantle spinel megacrysts, KilbourneHole, New MexicoEos, Vol. 70, No. 43, October 24, p. 1393. AbstractNew MexicoMegacrysts, STEM.
DS1993-1799
1993
Peacor, D.R.Yen-Hong Shau, Peacor, D.R., Essene, E.J.Formation of magnetic single-domain magnetite in ocean ridge basalts with implications for sea floor magnetismScience, Vol. 261, July 16, pp. 343-345Sea floorRifting, Tectonics
DS202004-0497
2020
Peaker, C.V.Ashfold, M.N.R., Goss, J.P., Green, B., May, P.W., Newton, M.E., Peaker, C.V.Nitrogen in diamond.Chemical Reviews, Vol. 120, 4, 10.1021/ acs.chemrev.9b00578 50p. PdfGlobalHPHT, CVD, synthetics

Abstract: Nitrogen is ubiquitous in both natural and laboratory-grown diamond, but the number and nature of the nitrogen-containing defects can have a profound effect on the diamond material and its properties. An ever-growing fraction of the supply of diamond appearing on the world market is now lab-grown. Here, we survey recent progress in two complementary diamond synthesis methods: high pressure high temperature (HPHT) growth and chemical vapor deposition (CVD), how each is allowing ever more precise control of nitrogen incorporation in the resulting diamond, and how the diamond produced by either method can be further processed (e.g., by implantation or annealing) to achieve a particular outcome or property. The burgeoning availability of diamond samples grown under well-defined conditions has also enabled huge advances in the characterization and understanding of nitrogen-containing defects in diamond alone and in association with vacancies, hydrogen, and transition metal atoms. Among these, the negatively charged nitrogen-vacancy (NV-) defect in diamond is attracting particular current interest in account of the many new and exciting opportunities it offers for, for example, quantum technologies, nanoscale magnetometry, and biosensing.
DS2003-0307
2003
Peakman, T.M.Dahl, J.E.P., Moldowan, J.M., Peakman, T.M., Clardy, J.C., Lobkovsky, E.Isolation and structural proof of the large diamond molecule, cycloheamantane (Angewandte Chemie, Vol. 42, 18, pp. 2040-44.GlobalMineral chemistry
DS200412-0398
2003
Peakman, T.M.Dahl, J.E.P., Moldowan, J.M., Peakman, T.M., Clardy, J.C., Lobkovsky, E., Olmstead, M.M., May, P.W., Davis, T.Isolation and structural proof of the large diamond molecule, cycloheamantane ( C26H30).Angewandte Chemie, Vol. 42, 18, pp. 2040-44.TechnologyMineral chemistry
DS201012-0075
2010
Peale, R.E.Brusentsova, T.N., Peale, R.E., Maukonen, D., Harlow, G.E., Boesenberg, J.S., Ebel, D.Far infrared spectroscopy of carbonate minerals.American Mineralogist, Vol. 95, pp. 1515-1522.TechnologyIR - not specific to diamonds
DS2002-0928
2002
PearceLe Roux, P.J., Le Roex, A.P., Schilling, J.G., Shimizu, N., Perkins, W.W., PearceMantle heterogeneity beneath the southern Mid-Atlantic Ridge: trace element evidenceEarth and Planetary Science Letters, Vol. 203, 1, pp. 479-98.MantleGeochemistry
DS201809-2113
2018
Pearce, A.Welford, K., Pearce, A., Geng, M., Dehler, S.A., Dickie, K.Crustal structure of Baffin Bay from constrained 3-D gravity inversion and deformable plate tectonic models. Geophysical Journal International, Vol. 214, 2, pp. 1281-1300. doi:1093/gji/ggy193Canada, NunavutGeophysics - gravity

Abstract: Mesozoic to Cenozoic continental rifting, breakup and spreading between North America and Greenland led to the opening, from south to north, of the Labrador Sea and eventually Baffin Bay between Baffin Island, northeast Canada and northwest Greenland. Baffin Bay lies at the northern limit of this extinct rift, transform and spreading system and remains largely underexplored. With the sparsity of existing crustal-scale geophysical investigations of Baffin Bay, regional potential field methods and quantitative deformation assessments based on plate reconstructions provide two means of examining Baffin Bay at the regional scale and drawing conclusions about its crustal structure, its rifting history and the role of pre-existing structures in its evolution. Despite the identification of extinct spreading axes and fracture zones based on gravity data, insights into the nature and structure of the underlying crust have only been gleaned from limited deep seismic experiments, mostly concentrated in the north and east where the continental shelf is shallower and wider. Baffin Bay is partially underlain by oceanic crust with zones of variable width of extended continental crust along its margins. 3-D gravity inversions, constrained by bathymetric and depth to basement constraints, have generated a range of 3-D crustal density models that collectively reveal an asymmetric distribution of extended continental crust, approximately 25-30?km thick, along the margins of Baffin Bay, with a wider zone on the Greenland margin. A zone of 5-13?km thick crust lies at the centre of Baffin Bay, with the thinnest crust (5?km thick) clearly aligning with Eocene spreading centres. The resolved crustal thicknesses are generally in agreement with available seismic constraints, with discrepancies mostly corresponding to zones of higher density lower crust along the Greenland margin and Nares Strait. Deformation modelling from independent plate reconstructions using GPlates of the rifted margins of Baffin Bay was performed to gauge the influence of original crustal thickness and the width of the deformation zone on the crustal thicknesses obtained from the gravity inversions. These results show the best match with the results from the gravity inversions for an original unstretched crustal thickness of 34-36?km, consistent with present-day crustal thicknesses derived from teleseismic studies beyond the likely continentward limits of rifting around the margins of Baffin Bay. The width of the deformation zone has only a minimal influence on the modelled crustal thicknesses if the zone is of sufficient width that edge effects do not interfere with the main modelled domain.
DS201901-0058
2018
Pearce, C.R.Prikryl, J., Stefansson, A., Pearce, C.R.Tracing olivine carbonation and serpentinization in CO2 rich fluids via magnesium exchange and isotopic fractionation.Geochimica et Cosmochimica Acta, Vol. 243, pp. 133-148.Mantleolivine

Abstract: Chemical exchange between seawater and the oceanic crust is thought to play a significant role in the regulation of the global magnesium (Mg) cycle, yet relatively little is known about the rates and mechanisms of Mg exchange in these crustal environments. In this study we experimentally characterize the extent, and nature, of Mg isotope fractionation during the carbonation and serpentinization of olivine (one of the principal minerals found in ultramafic rocks) under hydrothermal conditions. Olivine alteration was found to be incongruent, with the reactant fluid composition varying according to the extent of olivine dissolution and the precipitation of secondary minerals. In mildly acid water (pH???6.5), olivine dissolved to form Mg-Fe carbonate solid solutions and minor chrysotile. Upon carbonation and a decrease of CO2 in the water, the pH increased to >8, with chrysotile and brucite becoming the dominant alteration minerals. The Mg-rich carbonates preferentially incorporated lighter Mg isotopes, resulting in a ?0.5‰ increase of the ?26Mg composition of the fluid relative to olivine during the initial carbonation and serpentinization reactions. This was followed by a decrease in ?26Mg under higher pH conditions associated with the formation of brucite. Our experimental and modeling results therefore demonstrate that the ?26Mg composition of fluids involved in olivine alteration reflect the type and quantity of secondary Mg minerals formed, which in turn depend on the pH and CO2 concentration of the water. Comparison of these results with natural groundwaters and geothermal waters from basaltic terrains indicate that the ?26Mg composition of natural waters are likely to also be controlled by mafic rock dissolution and the preferential incorporation of isotopically light Mg into carbonates and isotopically heavy Mg into Mg-Si minerals. Together, these findings improve our understanding of Mg isotope systematics during water-rock interaction, and suggest that ?26Mg may be a useful tool for tracing reactions that are critical to geological CO2 sequestration.
DS1992-1174
1992
Pearce, J.Pearce, J.An element of recyclingNature, Vol. 360, No. 6405, December 17, p. 629-630GlobalGeochemistry, Mantle
DS1992-1175
1992
Pearce, J.Pearce, J.An element of recyclingNature, Vol. 360, Dec. 17, pp. 629-30.MantleXenoliths, Subduction
DS200612-1387
2006
Pearce, J.Straub, S., Pearce, J.Subduction zone evolution in 4-D.Goldschmidt Conference 16th. Annual, S6-06 theme abstract 1/8p. goldschmidt2006.orgMantleGeochemistry
DS201607-1387
2016
Pearce, J.Yang, J., Dilek, Y., Pearce, J., Schertl, H-P., Zhang, C.Diamonds and crustal recycling into deep mantle.IGC 35th., Session The Deep Earth 1 p. abstractMantleSubduction
DS1995-1453
1995
Pearce, J.A.Pearce, J.A., Peate, D.W.Tectonic implications of the composition of volcanic arc magmasAnnual Review of Earth Planetary Sciences, Vol. 23, pp. 251-286MantleTectonics, Magmas - arc
DS1998-1123
1998
Pearce, J.A.Parkinson, I.J., Pearce, J.A.Peridotites from the Izu Bonin Mariana Forearc: evidence for mantle melting and melt mantle interactionJournal of Petrology, Vol. 39, No. 9, pp. 1577-1618.MantlePeridotites - melting, Subduction
DS2003-1018
2003
Pearce, J.A.Niu, Y., O'Hara, M.J., Pearce, J.A.Initiation of subduction zones as a consequence of lateral compositional buoyancy:Journal of Petrology, Vol. 44, 5, pp. 851-66.MantleSubduction
DS200412-1441
2003
Pearce, J.A.Niu, Y., O'Hara, M.J., Pearce, J.A.Initiation of subduction zones as a consequence of lateral compositional buoyancy: contrast within the lithosphere: a petrologicJournal of Petrology, Vol. 44, 5, pp. 851-66.MantleSubduction
DS200512-0831
2005
Pearce, J.A.Pearce, J.A.Mantle preconditioning by melt extraction during flow: theory and petrogenetic implications.Journal of Petrology, Vol. 46, 5, pp. 973-997.MantleMelting
DS200612-1058
2006
Pearce, J.A.Pearce, J.A.When did subduction start - and how did it evolve?Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 12. abstract only.MantleSubduction
DS200912-0151
2009
Pearce, J.A.Dare, S.A.S., Pearce, J.A., McDonald, I.,Styles, M.T.Tectonic discrimination of peridotites using fO2 Cr# and Ga Ti Fe111 systematics in chrome spinel.Chemical Geology, Vol. 261, 3-4, April 30, pp. 199-216.TechnologyMineral chemistry database
DS202106-0931
2021
Pearce, J.A.Dewey, J.F., Kiseeva, E.S., Pearce, J.A., Robb, L.J.Precambrian tectonic evolution of Earth: an outline.South African Journal of Geology, Vol. 124, 1, pp. 141-162. pdfMantletectonics

Abstract: Space probes in our solar system have examined all bodies larger than about 400 km in diameter and shown that Earth is the only silicate planet with extant plate tectonics sensu stricto. Venus and Earth are about the same size at 12 000 km diameter, and close in density at 5 200 and 5 500 kg.m-3 respectively. Venus and Mars are stagnant lid planets; Mars may have had plate tectonics and Venus may have had alternating ca. 0.5 Ga periods of stagnant lid punctuated by short periods of plate turnover. In this paper, we contend that Earth has seen five, distinct, tectonic periods characterized by mainly different rock associations and patterns with rapid transitions between them; the Hadean to ca. 4.0 Ga, the Eo- and Palaeoarchaean to ca. 3.1 Ga, the Neoarchaean to ca. 2.5 Ga, the Proterozoic to ca. 0.8 Ga, and the Neoproterozoic and Phanerozoic. Plate tectonics sensu stricto, as we know it for present-day Earth, was operating during the Neoproterozoic and Phanerozoic, as witnessed by features such as obducted supra-subduction zone ophiolites, blueschists, jadeite, ruby, continental thin sediment sheets, continental shelf, edge, and rise assemblages, collisional sutures, and long strike-slip faults with large displacements. From rock associations and structures, nothing resembling plate tectonics operated prior to ca. 2.5 Ga. Archaean geology is almost wholly dissimilar from Proterozoic-Phanerozoic geology. Most of the Proterozoic operated in a plate tectonic milieu but, during the Archaean, Earth behaved in a non-plate tectonic way and was probably characterised by a stagnant lid with heat-loss by pluming and volcanism, together with diapiric inversion of tonalite-trondjemite-granodiorite (TTG) basement diapirs through sinking keels of greenstone supracrustals, and very minor mobilism. The Palaeoarchaean differed from the Neoarchaean in having a more blobby appearance whereas a crude linearity is typical of the Neoarchaean. The Hadean was probably a dry stagnant lid Earth with the bulk of its water delivered during the late heavy bombardment, when that thin mafic lithosphere was fragmented to sink into the asthenosphere and generate the copious TTG Ancient Grey Gneisses (AGG). During the Archaean, a stagnant unsegmented, lithospheric lid characterised Earth, although a case can be made for some form of mobilism with “block jostling”, rifting, compression and strike-slip faulting on a small scale. We conclude, following Burke and Dewey (1973), that there is no evidence for subduction on a global scale before about 2.5 Ga, although there is geochemical evidence for some form of local recycling of crustal material into the mantle during that period. After 2.5 Ga, linear/curvilinear deformation belts were developed, which “weld” cratons together and palaeomagnetism indicates that large, lateral, relative motions among continents had begun by at least 1.88 Ga. The “boring billion”, from about 1.8 to 0.8 Ga, was a period of two super-continents (Nuna, also known as Columbia, and Rodinia) characterised by substantial magmatism of intraplate type leading to the hypothesis that Earth had reverted to a single plate planet over this period; however, orogens with marginal accretionary tectonics and related magmatism and ore genesis indicate that plate tectonics was still taking place at and beyond the bounds of these supercontinents. The break-up of Rodinia heralded modern plate tectonics from about 0.8 Ga. Our conclusions are based, almost wholly, upon geological data sets, including petrology, ore geology and geochemistry, with minor input from modelling and theory.
DS1991-0593
1991
Pearce, K.Gould, C.C., Pearce, K.Informatiuon needs in the sciences: an assessmentResearch Libraries, Mountain View, 79p. Cost?GlobalInformation, Sciences
DS201711-2531
2017
Pearce, M.A.Timms, N.E., Erickson, T.M., Zanetti, M.R., Pearce, M.A., Cayron, C., Cavosie, A.J., Reddy, S.M., Wittman, A., Carpenter, P.K.Cubic zirconia in >2370 C impact melt records Earth's hottest crust.Earth and Planetary Science Letters, Vol. 478, pp. 52-58.Canada, QuebecMistastin crater

Abstract: Bolide impacts influence primordial evolution of planetary bodies because they can cause instantaneous melting and vaporization of both crust and impactors. Temperatures reached by impact-generated silicate melts are unknown because meteorite impacts are ephemeral, and established mineral and rock thermometers have limited temperature ranges. Consequently, impact melt temperatures in global bombardment models of the early Earth and Moon are poorly constrained, and may not accurately predict the survival, stabilization, geochemical evolution and cooling of early crustal materials. Here we show geological evidence for the transformation of zircon to cubic zirconia plus silica in impact melt from the 28 km diameter Mistastin Lake crater, Canada, which requires super-heating in excess of 2370?°C. This new temperature determination is the highest recorded from any crustal rock. Our phase heritage approach extends the thermometry range for impact melts by several hundred degrees, more closely bridging the gap between nature and theory. Profusion of >2370?°C superheated impact melt during high intensity bombardment of Hadean Earth likely facilitated consumption of early-formed crustal rocks and minerals, widespread volatilization of various species, including hydrates, and formation of dry, rigid, refractory crust.
DS202102-0197
2021
Pearce, M.A.Hill, E.J., Pearce, M.A., Stromberg, J.M.Improving automated geological logging of drill holes by incorporating multiscale spatial methods. ( not specific to diamonds)Mathematical Geosciences, Vol. 53, pp. 21-53. pdfGlobaldrill hole data

Abstract: Manually interpreting multivariate drill hole data is very time-consuming, and different geologists will produce different results due to the subjective nature of geological interpretation. Automated or semi-automated interpretation of numerical drill hole data is required to reduce time and subjectivity of this process. However, results from machine learning algorithms applied to drill holes, without reference to spatial information, typically result in numerous small-scale units. These small-scale units result not only from the presence of very small rock units, which may be below the scale of interest, but also from misclassification. A novel method is proposed that uses the continuous wavelet transform to identify geological boundaries and uses wavelet coefficients to indicate boundary strength. The wavelet coefficient is a useful measure of boundary strength because it reflects both wavelength and amplitude of features in the signal. This means that boundary strength is an indicator of the apparent thickness of geological units and the amount of change occurring at each geological boundary. For multivariate data, boundaries from multiple variables are combined and multiscale domains are calculated using the combined boundary strengths. The method is demonstrated using multi-element geochemical data from mineral exploration drill holes. The method is fast, reduces misclassification, provides a choice of scales of interpretation and results in hierarchical classification for large scales where domains may contain more than one rock type.
DS1996-1084
1996
Pearce, N.J.G.Pearce, N.J.G., Leng, M.J.The origin of carbonatites and related rocks from the Igaliko dyke swarm, Gardar Province, South Greenland.Lithos, Vol. 39, pp. 21-40.GreenlandCarbonatite, Geochemistry, geochronology
DS1997-0894
1997
Pearce, N.J.G.Pearce, N.J.G., Leng, M.J., Emeleus, C.H., Bedford, C.M.The origins of carbonatites and related rocks from the Gronnedal Ikanepheline syenite complex. C-O-Sr evid.Mineralogical Magazine, No. 407, August pp. 515-530.Greenland, south GreenlandCarbonatite
DS2003-0290
2003
Pearce, N.J.G.Coulson, I.M., Goodenough, K.M., Pearce, N.J.G., Leng, M.J.Carbonatites and lamprophyres of the Gardar Province - a window to the sub-GardarMineralogical Magazine, Vol. 67, 5, pp. 855-872.GreenlandCarbonatite
DS200412-0377
2003
Pearce, N.J.G.Coulson, I.M., Goodenough, K.M., Pearce, N.J.G., Leng, M.J.Carbonatites and lamprophyres of the Gardar Province - a window to the sub-Gardar mantle?Mineralogical Magazine, Vol. 67, 5, pp. 855-72.Europe, GreenlandCarbonatite
DS1986-0634
1986
Pearce, T.H.Pearce, T.H.Friends of the igneous rocks: first meetingGeoscience Canada, Vol. 14, No.1, March pp. 60-61GlobalConference Review
DS1990-1281
1990
Pearce, T.H.Russell, J.K., Nicholls, J., Stanley, C.R., Pearce, T.H.Pearce element ratiosEos, Vol. 71, No. 5, January 30, pp. 234, 235, 236, 246, 247GlobalIgneous rocks, Chemical variations -Pearce element ratios
DS1993-1205
1993
Pearce, T.H.Pearce, T.H.Analcime phenocrysts in igneous rocks: primary or secondary? DiscussionAmerican Mineralogist, Vol. 78, pp. 225-9.GlobalLeucite
DS1992-1176
1992
Pearse, P.H.Pearse, P.H.Natural resources in tomorrow's high tech economy: the search for sustainable development strategiesCentre for Resource Perspectives, No. 38, February pp. 15-23CanadaMining, Economics
DS1970-0173
1970
Pearse, T.D.Pearse, T.D.The Trapping Creek Ultramafic IntrusiveBsc. Thesis, Univ of British Columbia, 30pBritish ColumbiaAlkaline Rocks, Carbonatite
DS1991-1257
1991
PearsonOliver, N.H.S., Holcombe, Hill, PearsonTectono-metamorphic evolution of the Mary Kathleen fold belt: a reflection of mantle plume processes?Australian Journal of Earth Sciences, Vol. 38, No. 4, pp. 425-55.AustraliaCrustal evolution - not specific to diamond
DS1998-0535
1998
PearsonGriffin, W.L., Doyle, B.J., Ryan, Pearson, O'ReillyLithosphere structure and mantle terranes: Slave Craton, Canada7th International Kimberlite Conference Abstract, pp. 271-273.Northwest TerritoriesTerranes, xenoliths, Deposit - Ranch Lake, Jericho, Cross Lake
DS1999-0545
1999
PearsonPearson, Griffin, Doyle, O'Reilly, Van Acterbergh, KiviXenoliths from kimberlite pipes of the Lac de Gras area, Slave Craton, Canada. (DO18, 27, A154S)7th International Kimberlite Conference Nixon, Vol. 2, pp. 644-58.Northwest TerritoriesPetrography, mineral chemistry, analyses, thermometry
DS2000-0139
2000
PearsonCarlson, R.W., Janney, Shirey, Boyd, Pearson, IrvineChemical and age structure of the southern African lithospheric mantle: implications continent formationGeological Society of America (GSA) Abstracts, Vol. 32, No. 7, p.A-163.South AfricaMantle xenoliths - Kaapvaal Craton, Geophysics - seismics
DS2001-0062
2001
PearsonAulbach, S., Griffin, Pearson, O'Reilly, Doyle, KiviRe Os isotope evidence for Meso-Archean mantle beneath 2.7 Ga Contwoyto Terrane, implications tectonic historySlave-Kaapvaal Workshop, Sept. Ottawa, 5p. abstractMantleGeochemistry - major, trace elements, Slave Craton - tectonics
DS2001-0266
2001
PearsonDowall, D.P., Nowell, G.M., Pearson, Kjarsgaard, et al.Geochemistry of Slave and Somerset Island kimberlites29th. Yellowknife Geoscience Forum, Nov. 21-23, abstract p. 13-14.Northwest Territories, Somerset IslandGeochemistry - mantle lithosphere, Deposit - Jericho, Somerset Island
DS2001-0267
2001
PearsonDowall, D.P., Nowell, Pearson, Kjarsgaard, KopylovaComparative geochemistry of the source regions of southern African and Slave kimberlites.Slave-Kaapvaal Workshop, Sept. Ottawa, 6p. abstractNorthwest Territories, South AfricaGeochemistry, Geochronology - Lac de Gras, Contwyoto, Somerset
DS2001-0512
2001
PearsonIrvine, G.J., Pearson, Kopylova, Carlson, KjarsgaardThe age of two cratons: a platinum group elements (PGE) and Os isotopic study of peridotite c xenoliths from the Jericho, Somerset Isl.Slave-Kaapvaal Workshop, Sept. Ottawa, 5p. abstractNorthwest Territories, Nunavut, Somerset IslandGeochronology, Churchill Province, Slave Craton, Deposit - Jericho
DS2001-0706
2001
PearsonLuguet, A., Alard, O., Lorand, Pearson, Ryan, O'ReillyLaser ablation microprobe LAM ICPMS unravels the highly siderophile element geochemistry of oceanic mantle.Earth and Planetary Science Letters, Vol. 189, No. 3-4, July 15, pp. 285-94.MantleGeochemistry
DS2001-0869
2001
PearsonO'Reilly, S. Griffin, Djomani, Natapov, Pearson, DaviesThe mantle beneath the Slave Craton: composition and architectureSlave-Kaapvaal Workshop, Sept. Ottawa, 5p. abstractNorthwest TerritoriesPetrology, Tectonics - geochemistry, geophysics, plume
DS2001-0999
2001
PearsonRyan, C.G., Can Achterberg, Griffin, Pearson, O'ReillyNuclear microprobe analysis of melt inclusions in minerals: windows on metasomatic processes in mantleNuclear Instruments and Methods, Phys. Res. B., Vo.l81, pp. 578-85.MantleMetasomatism
DS2001-1178
2001
PearsonVan Achterbergh, A.E., Griffin, Kivi, Pearson, O'ReillyCarbonatites at 200 km: quenched melt inclusions in megacrystalline lherzolite xenoliths Slave Craton.Journal of South African Earth Sciences, Vol. 32, No. 1, p. A 35.(abs)Northwest TerritoriesCarbonatite, A 154 kimberlite
DS2002-0614
2002
PearsonGriffin, W.L., Wang, X., Jackson, Pearson, O'Reilly, XuZircon chemistry and magma mixing, SE China: in situ analysis of Hf isotopes, Tonglu and Pingtan complexes.Lithos, Vol.61, No.1-4, pp. 237-69., Vol.61, No.1-4, pp. 237-69.China, SoutheastGeochemistry - magma mixing, Geochronology
DS2002-0615
2002
PearsonGriffin, W.L., Wang, X., Jackson, Pearson, O'Reilly, XuZircon chemistry and magma mixing, SE China: in situ analysis of Hf isotopes, Tonglu and Pingtan complexes.Lithos, Vol.61, No.1-4, pp. 237-69., Vol.61, No.1-4, pp. 237-69.China, SoutheastGeochemistry - magma mixing, Geochronology
DS2002-1127
2002
PearsonNeumann, E.R., WulffPedersen, E., Pearson, SpencerMantle xenoliths from Tenerife: evidence for reactions between mantle peridotites and silicic carbonatite ..Journal of Petrology, Vol.43,5,pp.825-8., Vol.43,5,pp.825-8.Canary IslandsXenoliths, Melting
DS2002-1128
2002
PearsonNeumann, E.R., WulffPedersen, E., Pearson, SpencerMantle xenoliths from Tenerife: evidence for reactions between mantle peridotites and silicic carbonatite ..Journal of Petrology, Vol.43,5,pp.825-8., Vol.43,5,pp.825-8.Canary IslandsXenoliths, Melting
DS2002-1531
2002
PearsonSpetius, Z.V., Belousova, Griffin, O'Reilly, PearsonArchean sulphide inclusions in Paleozoic zircon megacrysts from the Mir kimberlite: implications datingEarth and Planetary Science Letters, Vol.199,1-2,pp.111-26., Vol.199,1-2,pp.111-26.Russia, YakutiaGeochronology - dating of diamonds, Deposit - Mir
DS2002-1532
2002
PearsonSpetius, Z.V., Belousova, Griffin, O'Reilly, PearsonArchean sulphide inclusions in Paleozoic zircon megacrysts from the Mir kimberlite: implications datingEarth and Planetary Science Letters, Vol.199,1-2,pp.111-26., Vol.199,1-2,pp.111-26.Russia, YakutiaGeochronology - dating of diamonds, Deposit - Mir
DS2002-1685
2002
PearsonWang, X., Griffin, O'Reilly, Zhou, Xu, Jackson, PearsonMorphology and geochemistry of zircons from late Mesozoic igneous complexes in coastal SE China:Mineralogical Magazine, Vol.66,2,pp. 235-52., Vol.66,2,pp. 235-52.China, southeastPetrogenesis
DS2002-1686
2002
PearsonWang, X., Griffin, O'Reilly, Zhou, Xu, Jackson, PearsonMorphology and geochemistry of zircons from late Mesozoic igneous complexes in coastal SE China:Mineralogical Magazine, Vol.66,2,pp. 235-52., Vol.66,2,pp. 235-52.China, southeastPetrogenesis
DS200712-0220
2007
PearsonDavies, G.R., Wasch, L., Van der Zwan, F., Morel, M.L.A., Nebel, Van Westrenen, Pearson, HellebrandThe origin of silica rich Kaapvaal lithospheric mantle.Plates, Plumes, and Paradigms, 1p. abstract p. A205.Africa, South AfricaDeposit - Kimberley
DS200812-1196
2008
PearsonUshkov, V.V., Ustinov, V.N., Smith, C.B., Bulanova, G.P., Lukyanova, L.I., Wiggers de Vries, D., PearsonKimozero, Karelia: a Diamondiferous paleoproterozoic metamorphosed volcaniclastic kimberlite.9IKC.com, 3p. extended abstractRussia, KareliaDeposit - Kimozero
DS200812-1321
2008
PearsonZheng, J.P., Griffin, W.L., O'Reilly, S.Y., Hu, Zhang, Tang, Su, Zhang, Pearson, Wamg, Lu.Continental collision and accretion recorded in the deep lithosphere of central China.Earth and Planetary Science Letters, Vol. 269, 3-4 May 30, pp. 496-506.ChinaBasaltic diatremes, geochronology, craton, tectonics
DS200912-0861
2009
PearsonZheng, J.P., Griffin, W.L., O'Reilly, S.Y., Zhao, J.H., Wu, Liu, Pearson, Zhang, Ma, Zhang, Yu, Su, TangNeoarchean ( 2.7-2.8 Ga) accretion beneath the North Chin a Craton: U Pb age, trace elements and Hf isotopes of zircons in Diamondiferous kimberlites.Lithos, Vol. 117, pp. 188-202.ChinaGeochronology
DS201112-0639
2011
PearsonMalkovets, V.G., Griffin, Pearson, Rezvukhin, O'Reilly, Pokhilenko, Garanin, Spetsius, LitasovLate metasomatic addition of garnet to the SCLM: Os-isotope evidence.Goldschmidt Conference 2011, abstract p.1395.RussiaUdachnaya, Daldyn
DS202103-0419
2021
Pearson, A.D.Vezinet, A., Pearson, A.D., Thomassot, E.Effects of contamination on whole rock isochrons in ancient rocks: a numerical modelling approach.Lithos, in press available, 44p. PdfGlobalmetamorphism

Abstract: Radiometric decay systems have played a crucial role in developing our understanding of the evolution of the early Earth. There are two main types of protocols for isotope measurements in geological materials: (i) bulk dissolution of rocks, or whole-grains and (ii) spatially resolved techniques (laser-ablation or ion-beam). These two approaches have sometimes led to results that are not easily reconciled for early Earth crustal rocks (? 3.6?Ga). While initial radiogenic isotope signatures (e.g. initial 176Hf/177Hf or initial 143Nd/144Nd) obtained from whole-rock protocols are significantly above chondritic values, indicative of extensive chemical differentiation of the mantle before 3.6?Ga, data from spatially resolved analysis of individual mineral growth domains point toward much less dramatic differentiation. This is indicated by the majority of data falling close to models of Earth's mantle that had not experienced major silicate melt removal into the crust. These data show chondritic or sub-chondritic signatures. Interpretations of whole rock isochrons are built on assumptions about the history and relationship of a number of different samples to each other. At the heart of these assumptions, the effects of secondary process-such as metasomatism-on isotopic compositions and consequently on the age and initial ratio of isochrons, are often considered negligible. In order to evaluate the possible effects of metasomatism and metamorphism on co-genetic igneous suites we modelled the impact of contamination by an external component on both the isochron slope (the apparent age) and the isochron intercept (the initial radiogenic isotope signature). A significant outcome is that the age significance of some of the modified isochron arrays remains to a large extent within uncertainty of the original crystallisation age of the igneous suite. In other words, the original age signature is preserved, but with lower precision. The intercept of the isochron, from which the initial isotope ratio is calculated, however is often significantly modified, which has consequences for the interpretation of these signatures. Our results provide an explanation for the discrepancy between whole-rock and spatially-resolved results observed in early Earth material. Lastly, our results, applied to studies of ancient crustal rocks, are interpreted as indicative of no significantly depleted mantle domains before 3.6?Ga, and no Hfsingle bondNd isotopes decoupling at that time.
DS201012-0617
2010
Pearson, A.J.Rege, S., Griffin, W.L., Pearson, A.J., Araujo, D., Zedgenizov, D., O'Reilly, S.Y.Trace element patterns of fibrous and monocrystalline diamonds: insights into mantle fluids.Lithos, Vol. 118, pp. 313-337.TechnologyDiamond genesis, morphology
DS1991-1309
1991
Pearson, C.Pearson, C.The world diamond marketInternational Gemological Symposium, June 20-24, 1991 Los Angeles, Gems and Gemology, Vol. 27, Spring, Program p. 10GlobalDiamond market
DS1993-1206
1993
Pearson, C.Pearson, C., et al.De Beers and the war... Brief overview of background of de Beers during Second World War. Critique of recent film/video on de Beers and the CSO.Preprint, 12p.South Africa, GlobalDe Beers film/video
DS1995-1454
1995
Pearson, C.Pearson, C.Diamond to the year 2000Address to the Gem Fest Europa 1995, Vicenza Italy June 12, 16p.GlobalDiamond outlook, CSO Marketing
DS1997-0895
1997
Pearson, C.Pearson, C.Diamonds - a global perspectiveWorld Diamond Conference, held Oct 7-8, 8p.GlobalDiamond market
DS1999-0539
1999
Pearson, C.Pearson, C.Diamonds: a global businessGemological Institute of America (GIA) International Gem. Symposium June 21-24, 7p.GlobalDiamond production, Overview
DS1999-0540
1999
Pearson, C.Pearson, C.Diamonds - a global businessGemological Institute of America (GIA) Symposium Handout, 7p.GlobalEconomics, Diamond markets
DS200512-0832
2005
Pearson, C.Pearson, C.Market changes and the outlook, paradigm shift the 1990's and the 21st century. Outlook express and synthetics.World Diamond Conference Nov. 23, Perth, 5p. textNews item - production, markets
DS1900-0362
1905
Pearson, C.A.Williams, A., Pearson, C.A.The Romance of Mining Containing Interesting Descriptions Of the Methods of Mining for Minerals in All Parts of the World.London: C.a. Pearson., 401P.Africa, South Africa, India, MyanmarMining, History, Kimberley
DS1998-1340
1998
Pearson, D.Shimizu, N., Pokhilenko, N.P., Boyd, F.R., Pearson, D.Trace element characteristics of garnet dunites/harzburgites, host rocks for peridotite diamond7th International Kimberlite Conference Abstract, pp. 803-4.Russia, SiberiaMineral chemistry, Peridotite diamonds
DS1999-0664
1999
Pearson, D.Shimizu, N., Pokhilenko, N.P., Boyd, F.R., Pearson, D.Trace element characteristics of garnet dunites /harzburgites. Host rocks for Siberian peridotitic ..7th International Kimberlite Conference Nixon, Vol. 2, pp. 773-82.Russia, Siberia, YakutiaPeridotite - diamond, geochemistry, Deposit - Udachnaya
DS1987-0571
1987
Pearson, D.G.Pearson, D.G., Davies, G.R., Nixon, P.H.Diamond facies garnet pyroxenites of Beni Bousera Morocco:recycled oceanic lithosphereTerra Cognita, Conference abstracts Oceanic and Continental Lithosphere:, Vol. 7, No. 4, Autumn, abstract only p. 622MoroccoBlank
DS1989-1185
1989
Pearson, D.G.Pearson, D.G., Davies, G.R., Nixon, D.H.Graphite-bearing pyroxenites from Morocco:evidence of recycled oceanic lithosphere And the origin of E type diamondsDiamond Workshop, International Geological Congress, July 15-16th. editors, pp. 83-86. AbstractMoroccoE type diamond Beni Bousera, Diamond morphology
DS1989-1186
1989
Pearson, D.G.Pearson, D.G., Davies, G.R., Nixon, P.H., Milledge, H.J.Graphitized diamonds from a peridotite massif in Morocco and Implications for anomalous diamondoccurrencesNature, Vol. 338, No. 6210, March 2, pp. 60-62MoroccoDiamond morphology, Diamond genesis
DS1990-1165
1990
Pearson, D.G.Pearson, D.G., Boyd, F.R., Nixon, P.H.Graphite-bearing mantle xenoliths from the Kaapvaal Craton: Implications for graphite and diamond genesisCarnegie Institution Geophysical Laboratory Annual Report of the Director, No. 2200, pp. 11-19Southern Africa, LesothoGraphite, Diamond genesis
DS1991-1310
1991
Pearson, D.G.Pearson, D.G., Boyd, F.R., Field, S.W., Pasteris, J.D., HaggertyGraphite bearing peridotites from the Kaapvaal craton: their carbon isotopic compositions and implications for peridotite thermobarometryProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 323-325South Africa, LesothoKimberley, Jagersfontein, spectrometry, Carbon composition -table
DS1991-1311
1991
Pearson, D.G.Pearson, D.G., Davies, G.R., Nixon, P.H.Diamond facies pyroxenites from the Beni Bousera peridotite massif And implications for the origin of eclogite xenolithsProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 326-328MoroccoGeochronology -oxygen isotope, Mineral chemistry
DS1991-1312
1991
Pearson, D.G.Pearson, D.G., Davies, G.R., Nixon, P.H., Greenwood, P.B.Oxygen isotope evidence for the origin of pyroxenites in the Beni Bousera peridotite massif, North Morocco: derivation from subducted oceaniclithosphereEarth and Planetary Science Letters, Vol. 102, No. 3/4, March pp. 289-301MoroccoGeochemistry, Ophiolite - Beni Bousera
DS1991-1313
1991
Pearson, D.G.Pearson, D.G., O'Reilly, S.Y., Griffin, W.L.The thermal evolution of cratonic lower crust/upper mantle: examples from eastern Australia and southern AfricaProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 332-333Australia, Southern AfricaKaapvaal craton, Geothermobarometry
DS1991-1314
1991
Pearson, D.G.Pearson, D.G., Shirey, S.B., Carlson, R.W., Boyd, F.R., Nixon, P.H.Rhenium-osmium isotope systematics in southern African and SiberanProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 329-331Southern Africa, RussiaGeochronology -Re/Os isotope, Kaapvaal xenoliths
DS1991-1360
1991
Pearson, D.G.Pokhilenko, N.P., Pearson, D.G., Boyd, F.R., Sobolev, N.V.Megacrystalline dunites and peridotites: hosts for Siberian diamondsCarnegie Institute Annual Report of the Director Geophysical Laboratory, No. 2250, pp. 11-18Russia, SiberiaDunites, Peridotites
DS1992-1177
1992
Pearson, D.G.Pearson, D.G., Taylor, L.A.On isotope constraints on the petrogenesis of eclogite xenolithsEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p.376South AfricaBellsbank, Geochronology
DS1993-0150
1993
Pearson, D.G.Boyd, F.R., Pearson, D.G., Nixon, P.H., Mertzman, S.A.Low calcium garnet harzburgites from southern Africa: their relations to craton structure and diamond crystallizationContribution to Mineralogy and Petrology, Vol. 113, pp. 352-366South AfricaGarnet, Mineralogy
DS1993-0151
1993
Pearson, D.G.Boyd, F.R., Pearson, D.G., Pokhilenko, N.P., Mertzman, S.A.Cratonic mantle composition: evidence from Siberian xenolithsEos, Transactions, American Geophysical Union, Vol. 74, No. 16, April 20, supplement abstract p. 321Russia, SiberiaBulk composition, Mineral chemistry
DS1993-0320
1993
Pearson, D.G.Davies, G.R., Nixon, P.H., Pearson, D.G., Obata, M.Tectonic implications of graphitized diamonds from the Ronda peridotitemassif, southern SpainGeology, Vol. 21, No. 5, May pp. 471-474GlobalTectonics, Graphite morphology, Pyroxene
DS1993-1207
1993
Pearson, D.G.Pearson, D.G., Davies, G.R., Nixon, P.H.Geochemical constraints on the petrogenesis of diamond facies pyroxenites from the Beni Boussera peridotite Massif, North Morocco.Journal of Petrology, Vol. 34, No. 1, February pp. 125-172.MoroccoDiamond, geochemistry, Pyroxenite
DS1993-1247
1993
Pearson, D.G.Pokhilenko, N.P., Sobolev N.V., Boyd, F.R., Pearson, D.G., Shimizum N.Megacrystalline pyrope peridotites in the lithosphere of the Siberianplatform: mineralogy, geochemical pecularities and the problem of their origin.Russian Geology and Geophysics, Vol. 34, No. 1, pp. 1-12.Russia, Commonwealth of Independent States (CIS), SiberiaPyrope peridotites, Siberian Platform, Geochemistry
DS1994-0201
1994
Pearson, D.G.Boyd, F.R., Pearson, D.G., Olson Hoal, K.E., Hoal, B.G.Composition and age of Namibian peridotite xenolith: a comparison of cratonic and non cratonic lithosphere.Eos, Vol. 75, No. 16, April 19, p. 192.NamibiaXenoliths, Peridotites
DS1994-0256
1994
Pearson, D.G.Canil, D., O'Neill, H.S., Pearson, D.G., Rudnick, R.L.Ferric ion in peridotites and mantle oxidation statesEarth Planet. Sci. Letters, Vol. 123, No. 1-2, May pp. 205-220.MantlePeridotites
DS1994-1347
1994
Pearson, D.G.Pearson, D.G., Boyd, F.R., Haggerty, S.E., Pasteris, J.D.The characterization and origin of graphite in cratonic lithosphericmantle: a petrological carbon isotope and Raman spectroscopic study.Contr. Mineralogy and Petrology, Vol. 116, No. 3, pp. 449-466.MantleGeochronology, Graphite
DS1994-1348
1994
Pearson, D.G.Pearson, D.G., Snyder, G.A., Shirley, S.B., Taylor, L.A.Rhenium- Osmium (Re-Os) isotope evidence for a mid-Archean age of Diamondiferous eclogite xenoliths -Udachnaya.Mineralogical Magazine, Vol. 58A, pp. 705-706. AbstractRussia, YakutiaGeochronology, Deposit -Udachnaya
DS1995-0192
1995
Pearson, D.G.Boyd, F.R., Pokhilenko, N.P., Pearson, D.G., Sobolev, N.V.Peridotite xenoliths from the Udachnaya kimberlite pipeProceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 57-59.Russia, YakutiaXenoliths, Deposit -Udachnaya
DS1995-0270
1995
Pearson, D.G.Carlson, R.W, Shirey, S.B., Pearson, D.G., Boyd, F.R.The mantle beneath continentsCarnegie Institution Yearbook 93 for 1993-1994., pp. 109-119.South Africa, Russia, SiberiaMantle, Plumes, keels
DS1995-0804
1995
Pearson, D.G.Hoal, B.G., Hoal, K.E.O., Boyd, F.R., Pearson, D.G.Tectonic setting and mantle composition inferred from peridotite Gibeon kimberlite field, Namibia.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 239-241.NamibiaTectonics, Deposit -Gibeon area
DS1995-0805
1995
Pearson, D.G.Hoal, B.G., Hoal, R.E.O., Boyd, F.R., Pearson, D.G.Age constraints on crustal and mantle lithosphere beneath the Gibean kimberlite field, Namibia.South. African Journal of Geology, Vol. 98, No. 2, June pp. 112-118.NamibiaGeochronology, Deposit -Gibeon field
DS1995-1455
1995
Pearson, D.G.Pearson, D.G., Carlson, R.W., Nixon, P.H.Stabilizaton of Archean lithospheric mantle: a Re:Os isotope study of peridotite xenoliths Kaapvaal CratonEarth and Planetary Science Letters, Vol. 134, No. 3-4, Sept. 1, pp. 341-358South AfricaXenoliths, Kaapvaal Craton
DS1995-1456
1995
Pearson, D.G.Pearson, D.G., Carlson, R.W., Nixon, P.H.Stabilization of Archean lithospheric mantle: a RE; OS isotope study of peridotite xenoliths Kaapvaal Craton.Earth and Planetary Science Letters, Vol. 134, No. 3-4, Sept. 1, pp. 341-358.South AfricaXenoliths, Craton -Kaapvaal
DS1995-1457
1995
Pearson, D.G.Pearson, D.G., Davies, G.R., Nixon, P.H.Orogenic ultramafic rocks of ultra high pressure (UHP) (diamond facies) originCambridge University of Press, pp. 456-510.Morocco, Spain, British Columbia, Russia, Tibet, Burkina FasoPeridotite - Beni Bousera, Ronda, Ophiolites - diamondiferous
DS1995-1458
1995
Pearson, D.G.Pearson, D.G., Kelley, S.P., Pokhilenko, N.P., Boyd, F.R.Laser 40 Ar-39 Ar analyses of phlogopites from kimberlites and theirxenoliths: constraints eruptionProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 424-426.Russia, Yakutia, South AfricaGeochronology -eruption ages, Argon, Deposit -Mir, Udachnaya, Leningrad, Letseng, Kampfersda
DS1995-1459
1995
Pearson, D.G.Pearson, D.G., Meyer, H.O.A., Boyd, F.R., Shirey, S.B.Rhenium- Osmium (Re-Os) isotope evidence for late Archean stabilization of thick lithosphere mantle keel beneath Kirkland LakeProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 427-429.Ontario, Kirkland LakeGeochronology, Mantle keel
DS1995-1460
1995
Pearson, D.G.Pearson, D.G., Rogers, N.W., Irving, A.J., Smith, C.B.Source regions of kimberlites and lamproites: constraints from Rhenium- Osmium (Rhenium- Osmium (Re-Os))isotopes.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 430-432.South AfricaGeochronology, Lamproites
DS1995-1461
1995
Pearson, D.G.Pearson, D.G., Shirey, S.B., Carlson, R.W, Boyd, F.R.Rhenium- Osmium (Re-Os),samarium-neodymium (Sm-Nd) Rubidium-Strontium isotope evidence for thick Archean lithospheric mantle beneath the Siberian craton ....Geochimica et Cosmochimica Acta, Vol. 59, No. 3, pp. 959-977.Russia, SiberiaMantle geochemistry, geochronology, Metasomatism -multistage
DS1995-1462
1995
Pearson, D.G.Pearson, D.G., Snyder, G.A., Shirey, S.B., Taylor, L.A.Archean Rhenium- Osmium (Re-Os) age for Siberian eclogites and constraints on Archeantectonics.Nature, Vol. 374, No. 6524, April 20, pp. 711-713.Russia, Siberia, RussiaGeochronology, Eclogites
DS1995-1736
1995
Pearson, D.G.Shimizu, N., Pokhilenko, N.P., Biyd, F.R., Pearson, D.G.Geochemical characteristics of mantle xenoliths from the Udachnaya kimberlite pipe.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 524-525.Russia, YakutiaGeochemistry, Deposit -Udachnaya
DS1996-1085
1996
Pearson, D.G.Pearson, D.G., Nixon, P.H.Diamonds in young orogenic belts: graphitised diamonds from Beni Bousera: acomparison with kimberlite derivedAfrica Geoscience Review, Vol. 3, No. 2, pp. 295-316.MoroccoGraphite aggregates, diamond genesis, exploration, Diamond facies pyroxenites
DS1998-0215
1998
Pearson, D.G.Carlson, R.W., Pearson, D.G., Boyd, F.R., Shirey, IrvineRegional age variation of the southern African mantle: significance for model lithospheric mantle formation..7th International Kimberlite Conference Abstract, pp. 135-137.South AfricaGeochronology, Craton - on and off ages
DS1998-0566
1998
Pearson, D.G.Hamilton, M.A., Pearson, D.G., Stern R.A., Boyd, F.R.Constraints on MARID petrogenesis: SHRIMP II uranium-lead (U-Pb) zircon evidence for pre-eruption Metasomatism..7th International Kimberlite Conference Abstract, pp. 296-8.South AfricaGeochronology, Deposit - KampfersdaM.
DS1998-0596
1998
Pearson, D.G.Hauri, E.H., Pearson, D.G., Bulanova, G.P., Milledge, H.Microscale variations in Carbon and Nitrogen isotopes within mantle diamonds revealed by SIMS.7th International Kimberlite Conference Abstract, pp. 317-9.Russia, Siberia, southern AfricaDiamond morphology, Geochronology
DS1998-0660
1998
Pearson, D.G.Irvine, G.J., Pearson, D.G., Carlson, R.W., Boyd, F.R.Platinum group element constraints on the origin of cratonic peridotites: a study of Kimberley xenoliths..7th International Kimberlite Conference Abstract, pp. 346-8.South AfricaXenoliths - platinum group elements (PGE), Deposit - Kimberley
DS1998-1078
1998
Pearson, D.G.Nixon, P.H., Pearson, D.G.Ultra-magmatism komatiites of Phanerozoic age from southeast Spain7th International Kimberlite Conference Abstract, pp. 625-7.GlobalStructure - spinifex textured harzburgites, Geochemistry
DS1998-1080
1998
Pearson, D.G.Nowell, G.M., Kempton, P.D., Pearson, D.G.Hafnium - neodymium isotope systematics of kimberlites: relevance to terrestrial Hafnium - neodymium systematics.7th International Kimberlite Conference Abstract, pp. 628-30.MantleChondrites - bulk silicate earth, Geochronology
DS1998-1081
1998
Pearson, D.G.Nowell, G.M., Kempton, P.D., Pearson, D.G.Trace element and isotope geochemistry of Siberian kimberlites7th International Kimberlite Conference Abstract, pp. 631-3.Russia, YakutiaGeochemistry, Group I kimberlites
DS1998-1082
1998
Pearson, D.G.Nowell, G.M., Pearson, D.G.Hafnium isotope constraints on the genesis of kimberlitic megacrysts : evidence for a deep mantle component.7th International Kimberlite Conference Abstract, pp. 634-6.South AfricaKimberlite magmatism, Deposit - Frank Smith, Monastery
DS1998-1083
1998
Pearson, D.G.Nowell, G.M., Pearson, D.G., Kempton, irving, TurnerA Hafnium isotope study of lamproites: implications for their origins and relationships to kimberlite.7th International Kimberlite Conference Abstract, pp. 637-9.Montana, Australia, SpainGeochronology, Lamproites
DS1998-1084
1998
Pearson, D.G.Nowell, G.M., Pearson, D.G., Kempton, Noble, SmithThe source regions/components of kimberlites: constraints from Hafnium - neodymium isotope systematics.7th. Kimberlite Conference abstract, pp. 640-2.South AfricaGeochronology, Group I, II
DS1998-1133
1998
Pearson, D.G.Pearson, D.G., Carlson, R.W., Boyd, F.R., Shiry, NixonLithospheric mantle growth around cratons: a Rhenium- Osmium (Re-Os) isotope study of peridotite xenoliths East Griqualand.7th. Kimberlite Conference abstract, pp. 658-60.South AfricaCraton, Geochronology - xenoliths
DS1998-1134
1998
Pearson, D.G.Pearson, D.G., Davies, R., Shirey, Carlson, R., Griffin.The age and origin of eastern Australian diamonds: Rhenium- Osmium (Re-Os) isotope evidence from sulfide inclusions...7th. Kimberlite Conference abstract, pp. 664-6.Australia, New South WalesDiamond inclusions, geochronology, Deposit - Copeton, Bingara
DS1998-1135
1998
Pearson, D.G.Pearson, D.G., Ionov, D., Carlson, ShireyLithospheric evolution in circum cratonic settings: a Re- Os isotope studyof peridotite xenoliths Vitim ...Mineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 1147-8.Russia, VitiM.Geochemistry - whole rock, Spinels
DS1998-1136
1998
Pearson, D.G.Pearson, D.G., Milledge, H.J.Diamond growth conditions and preservation: inferences from trace elements in a large garnet inclusion...7th. Kimberlite Conference abstract, pp. 667-9.Russia, SiberiaDiamond morphology, diamond inclusions, Deposit - Udachnaya
DS1998-1137
1998
Pearson, D.G.Pearson, D.G., Shirey, S., Bulanova, Carlson, MilledgeDating diamonds using Rhenium- Osmium (Re-Os) isotope technique: a study of sulfide inclusions in Siberian diamonds.7th. Kimberlite Conference abstract, pp. 661-3.Russia, SiberiaGeochronology, Deposit - Udachnaya
DS1998-1138
1998
Pearson, D.G.Pearson, D.G., Shirey, S.B., Carlson, R.W.Sulphide inclusions in diamonds from the Koffiefontein kimberlite:constraints on diamond ages and mantle R-OsEarth and Planetary Science Letters, Vol. 160, No. 3-4, Aug. 1, pp. 311-326.South AfricaGeochronology, diamond inclusions, Deposit - Koffiefontein
DS1999-0512
1999
Pearson, D.G.Nixon, P.H., Pearson, D.G., Condliffem E.Harzburgites with spinifex texture from southeast Spain - petrological and geochemical constraints on origin.7th International Kimberlite Conference Nixon, Vol. 2, pp. 605-15.GlobalHarzburgites, mineralogy, regional tectonics, Cerro del Almirez, Montenegro
DS1999-0516
1999
Pearson, D.G.Nowell, G.M., Pearson, D.G., Kempton, Noble, SmithOrigins of kimberlites: a Hafnium isotope perspective7th International Kimberlite Conference Nixon, Vol. 2, pp. 616-24.South AfricaGeochronology, Group I, II, model, subduction
DS1999-0541
1999
Pearson, D.G.Pearson, D.G.The age of continental rootsLithos, Vol. 48, No. 1-4, Sept. pp. 171-94.MantleGeochronology, Craton
DS1999-0542
1999
Pearson, D.G.Pearson, D.G., Shirey, Bulanova, Carlson, MilledgeDating and paragenetic distinction of diamonds using Re- Os isotope system: application Siberian diamonds.7th International Kimberlite Conference Nixon, Vol. 2, pp. 637-43.Russia, SiberiaGeochronology, sulphide inclusions, age determination, Udachnaya, Mir
DS1999-0543
1999
Pearson, D.G.Pearson, D.G., Shirey, S.B.Isotopic dating of diamondsSeg Reviews In Economic Geology, Vol. 12, Chapter 6, pp. 143-72.GlobalDiamond - inclusions, isotopic, Age determinations - silicate, sulphide
DS1999-0544
1999
Pearson, D.G.Pearson, D.G., Shirey, S.B., Milledge, H.J.Re Os isotope measurements of single sulphide inclusions in a Siberian diamond and its nitrogen ...Geochimica et Cosmochimica Acta, Vol. 63, No. 5, Mar. 1, pp. 7-3-12.Russia, SiberiaGeochronology - diamond inclusions, Nitrogen aggregation systematics
DS2001-0511
2001
Pearson, D.G.Irvine, G.J., Pearson, D.G., Carlson, R.W.Lithospheric mantle evolution of the Kaapvaal Craton : a Rhenium- Osmium (Re-Os) isotope study of peridotite nodules kimberlitesGeophysical Research Letters, Vol. 28, No. 13, July 1, pp. 2505-08.LesothoGeochronology
DS2001-0895
2001
Pearson, D.G.Pearson, D.G.New isotopic techniques for dating diamonds: examples from the Siberian Craton29th. Yellowknife Geoscience Forum, Nov. 21-23, abstract p. 64-5.RussiaGeochronology
DS2001-0896
2001
Pearson, D.G.Pearson, D.G., Biyd, F.R., Simon, N.S.C.Modal mineralogy and geochemistry of Kaapvaal peridotites: the origin of garnet diopside - stabilitySlave-Kaapvaal Workshop, Sept. Ottawa, 7p. abstractSouth AfricaCraton - stability
DS2002-0221
2002
Pearson, D.G.Bulanova, G.P., Pearson, D.G., Hauri, E.H., Griffin, B.J.Carbon and nitrogen isotope systematics within a sector growth diamond from the Mir kimberlite, Yakutia.Chemical Geology, Vol. 188, No. 1-2, pp. 105-123.Russia, YakutiaGeochronology, Deposit - Mir
DS2002-0681
2002
Pearson, D.G.Hauri, E.H., Wang, J., Pearson, D.G., Bulanova, G.P.Microanalysis of 13C 15 N and N abundances in diamonds by secondary ion mass spectrometry.Chemical Geology, Vol.145, 1-2, Apr.15, pp. 149-63.Russia, SiberiaDiamond - inclusions, carbon, nitrogen isotopes
DS2002-1235
2002
Pearson, D.G.Pearson, D.G., Nowell, G.M.The continental lithospheric mantle characteristics and significance as a mantle reservoirPhilosophical Transactions, Royal Society of London Series A Mathematical, Vol.1800, pp. 2383-2410.MantleTectonics, geochemistry
DS2003-0146
2003
Pearson, D.G.Boyd, F.R., Hoal, K.O., Hoal, B.G., Nicox, P.H., Pearson, D.G., Kingston, M.J.Garnet lherzolites from Louwrencia, Namibia: bulk sample compositions and P/T8 Ikc Www.venuewest.com/8ikc/program.htm, Session 6, AbstractNamibiaMantle petrology
DS2003-0182
2003
Pearson, D.G.Bulanova, G.P., Muchemwa, E., Pearson, D.G., Griffin, B.J., Kelly, S., KlemmeSyngenetic inclusions of yeminite in diamond from Sese kimberlite ( Zimbabwe) -8ikc, Www.venuewest.com/8ikc/program.htm, Session 3, POSTER abstractZimbabweDiamonds - inclusions, Deposit - Sese
DS2003-0183
2003
Pearson, D.G.Bulanova, G.P., Pearson, D.G., Hauri, E.H., Milledge, H.J., Barashkov, Yu.P.Dynamics of diamond growth: evidence from isotope and FTIR trends8ikc, Www.venuewest.com/8ikc/program.htm, Session 3, POSTER abstractRussiaDiamonds - inclusions, Geochronology, morphology
DS2003-0313
2003
Pearson, D.G.Davies, G.R., Stolz, A.J., Mahotkin, I.L., Nowell, G.M., Pearson, D.G.Trace element and Sr Pb Nd Hf isotope evidence for ancient fluid related enrichment in8 Ikc Www.venuewest.com/8ikc/program.htm, Session 7, POSTER abstractRussia, Aldan ShieldGeochronology
DS2003-0347
2003
Pearson, D.G.Dowall, D.P., Pearson, D.G., Nowell, G.M., Kjarsgaard, B.A., Armstrong, J.Comparative geochemistry of kimberlites from the Lac de Gras field, NWT - an8 Ikc Www.venuewest.com/8ikc/program.htm, Session 7, AbstractNorthwest TerritoriesKimberlite petrogenesis, Geochronology, database 98
DS2003-0540
2003
Pearson, D.G.Hamilton, M.A., Sobolev, N.V., Stern, R.A., Pearson, D.G.SHRIMP U Pb dating of a perovskite inclusion in diamond: evidence for a syneruption8ikc, Www.venuewest.com/8ikc/program.htm, Session 3, POSTER abstractRussia, Siberia, YakutiaDiamonds - inclusions, geochronology, Deposit - Sytykanskaya
DS2003-0622
2003
Pearson, D.G.Irvine, G.J., Pearson, D.G., Kjarsgaard, B.A., Carlson, R.W., Kopylova, M.G.A Re Os isotope and PGE study of kimberlite derived peridotite xenoliths fromLithos, Vol. 71, 2-4, pp. 461-488.South Africa, Northwest Territories, NunavutGeochronology
DS2003-0631
2003
Pearson, D.G.Jacob, D.E., Fung, A., Jagoutz, E., Pearson, D.G.Petrology and geochemistry of eclogite xenoliths from the Ekati kimberlite area8ikc, Www.venuewest.com/8ikc/program.htm, Session 2, POSTER abstractNorthwest TerritoriesEclogites and Diamonds, Deposit - Ekati
DS2003-1020
2003
Pearson, D.G.Nowell, G.M., Pearson, D.G., Jacob, D.E., Spetsius, S., Nixon, P.H., HaggertyThe origin of alkremites and related rocks: a Lu Hf Rb Sr and Sm Nd isotope study8ikc, Www.venuewest.com/8ikc/program.htm, Session 4, POSTER abstractRussia, YakutiaMantle geochemistry, Deposit - Udachnaya
DS2003-1050
2003
Pearson, D.G.Pearson, D.G., Nowell, G.M., Dowall, D.P., Kjarsgaard, B.A., Kopylova, M.G.The relative roles of lithosphere and convecting mantle in kimberlites from the Slave8 Ikc Www.venuewest.com/8ikc/program.htm, Session 7, AbstractNorthwest TerritoriesKimberlite petrogenesis, Geochronology
DS2003-1278
2003
Pearson, D.G.Simon, N.S., Irvine, G.J., Davies, G.R., Pearson, D.G., Carlson, R.W.The origin of garnet and clinopyroxene in 'depleted' Kaapvaal peridotitesLithos, Vol. 71, 2-4, pp. 289-322.South AfricaMineral chemistry
DS2003-1279
2003
Pearson, D.G.Simon, N.S.C., Carlosn, R.W., Davies, D.R., Nowell, G.M., Pearson, D.G.OS SR ND HF isotope evidence for the ancient depletion and subsequent multi stage8ikc, Www.venuewest.com/8ikc/program.htm, Session 4, POSTER abstractSouth AfricaMantle geochemistry, Geochronology
DS200412-0193
2003
Pearson, D.G.Boyd, F.R., Hoal, K.O., Hoal, B.G., Nicox, P.H., Pearson, D.G., Kingston, M.J.Garnet lherzolites from Louwrencia, Namibia: bulk sample compositions and P/T relations.8 IKC Program, Session 6, AbstractAfrica, NamibiaMantle petrology
DS200412-0197
2004
Pearson, D.G.Boyd, S.R., Pearson, D.G., Hoal, K.O., Hoal, B.G., Nixon, P.H., Kingston, M.J., Mertzman, S.A.Garnet lherzolites from Louwrensia, Namibia: bulk composition and P/T relations.Lithos, Vol. 77, 1-4, Sept. pp. 573-592.Africa, NamibiaGeothermometry, peridotite, Kaapvaal, mantle, lithosphe
DS200412-0239
2004
Pearson, D.G.Bulanova, G.P., Muchemwa, E., Pearson, D.G., Griffin, B.J., Kelley, S.P., Klemme, S., Smith, C.B.Syngenetic inclusions of yimengite in diamond from Sese kimberlite - evidence for metasomatic conditions of growth.Lithos, Vol. 77, 1-4, Sept. pp. 181-192.Africa, ZimbabweMagnetoplumbite, grochronology argon, mantle, metasomat
DS200412-0413
2003
Pearson, D.G.Davies, G.R., Stolz, A.J., Mahotkin, I.L., Nowell, G.M., Pearson, D.G.Trace element and Sr Pb Nd Hf isotope evidence for ancient fluid related enrichment in the source region of Aldan Shield lamproi8 IKC Program, Session 7, POSTER abstractRussia, Aldan ShieldKimberlite petrogenesis, geochronology
DS200412-0474
2003
Pearson, D.G.Dowall, D.P., Pearson, D.G., Nowell, G.M., Kjarsgaard, B.A., Armstrong, J., Hortswood, M.S.A.Comparative geochemistry of kimberlites from the Lac de Gras field, NWT - an integrated isotopic and elemental study.8 IKC Program, Session 7, AbstractCanada, Northwest TerritoriesKimberlite petrogenesis, Database 98
DS200412-0874
2003
Pearson, D.G.Irvine, G.J., Pearson, D.G., Kjarsgaard, B.A., Carlson, R.W., Kopylova, M.G., Dreibus, G.A Re Os isotope and PGE study of kimberlite derived peridotite xenoliths from Somerset Island and a comparison to the Slave andLithos, Vol. 71, 2-4, pp. 461-488.Africa, South Africa, Northwest Territories, NunavutGeochronology
DS200412-1448
2004
Pearson, D.G.Nowell, G.M., Pearson, D.G., Bell, D.R., Carlson, R.W., Smith, C.B., Kempton, P.D., Noble, S.R.Hf isotope systematics of kimberlites and their megacrysts: new constraints on their source regions.Journal of Petrology, Vol. 45, 8, pp. 1583-1612.Africa, South AfricaGeochronology
DS200412-1508
2004
Pearson, D.G.Pearson, D.G., irvine, G.J., Ionov, D.A., Boyd, F.R., Dreibus, G.E.The Re Os systematics and platinum group element fractionation during mantle melt extraction: a study of massif and xenolith perChemical Geology, Vol. 208, 1-4, pp. 29-59.Africa, Lesotho, Namibia, MoroccoGeochronology, mantle melt extraction
DS200412-1509
2003
Pearson, D.G.Pearson, D.G., Nowell, G.M., Dowall, D.P., Kjarsgaard, B.A., Kopylova, M.G., Armstrong, J.A.The relative roles of lithosphere and convecting mantle in kimberlites from the Slave Province NWT: constraints from Re Os isoto8 IKC Program, Session 7, AbstractCanada, Northwest TerritoriesKimberlite petrogenesis Geochronology
DS200412-1831
2003
Pearson, D.G.Simon, N.S., Irvine, G.J., Davies, G.R., Pearson, D.G., Carlson, R.W.The origin of garnet and clinopyroxene in 'depleted' Kaapvaal peridotites.Lithos, Vol. 71, 2-4, pp. 289-322.Africa, South AfricaMineral chemistry
DS200512-0140
2005
Pearson, D.G.Carlson, R.W., Pearson, D.G., James, D.E.Physical, chemical and chronological characteristics of continental mantle.Reviews of Geophysics, Vol. 43, 1, RG1001 10.1029/2004 TG000156MantleGeochemistry
DS200512-0220
2005
Pearson, D.G.Day, J.M.D., Hilton, D.R., Pearson, D.G., MacPherson, C.G., Kjarsgaard, B.A., Janney, P.E.Absence of a high time integrated 3He (U-Th) source in the mantle beneath continents.Geology, Vol. 33, 9, Sept. pp. 733-736.Mantle, Canada, Africa, South Africa, UgandaGeochronology - helium isotopes
DS200512-1072
2003
Pearson, D.G.Tappe, S., Foley, S.F., Pearson, D.G.African type kamafugites: a mineralogical and geochemical comparison with their Italian and Brazilian analogues.Periodico di Mineralogia, (in english), Vol. LXX11, 1. April, pp. 51-77.South America, Brazil, Africa, UgandaMelilite, katsilite, Toro Ankole Rift
DS200512-1084
2005
Pearson, D.G.Thompson, R.N., Ottley, C.J., Smith, P.M., Pearson, D.G., Dickin, A.P., Morrison, M.A., Leat, P.T., Gibson, S.A.Source of the Quaternary alkalic basalts, picrites and basanites of the Potrillo volcanic field, New Mexico, USA: lithosphere or convecting mantle?Journal of Petrology, Vol. 46, 8, pp. 1603-1643.United States, New Mexico, Colorado PlateauConvection
DS200512-1085
2005
Pearson, D.G.Thompson, R.N., Ottley, C.J., Smith, P.M., Pearson, D.G., Dickin, A.P., Morrison, M.A., Leat, P.T., Gibson, S.A.Source of the Quaternary alkaline basalts, picrites and basanites of the Potrillo volcanic field, New Mexico, USA: lithosphere or convecting mantle?Journal of Petrology, Vol. 46, 8, pp. 1603-1643.United States, New Mexico, Colorado PlateauPicrite, basanites
DS200612-0315
2006
Pearson, D.G.Davies, G.R., Stolz, A.J., Mahotkin, I.L., Nowell, G.M., Pearson, D.G.Trace element and Sr Pb Nd Hf isotope evidence for ancient fluid dominated enrichment of the source of the Aldan Shield, lamproites.Journal of Petrology, Vol. 47, 6, pp. 1119-1146.RussiaGeochronology, geochemistry lamproites
DS200612-0534
2006
Pearson, D.G.Harlou, R., Pearson, D.G., Davidson, J.P., Kamenetsky, V.S., Yaxley, G.M.Source variability and crustal contamination of the Baffin Island picrites - coupled Sr isotope and trace element study of individual melt inclusions.Geochimica et Cosmochimica Acta, Vol. 70, 18, 1, p. 11, abstract only.Canada, Nunavut, Baffin IslandPicrite
DS200612-0840
2006
Pearson, D.G.Luguet, A., Nowell, G.M., Pearson, D.G., Dreher, S.T.186 Os and 187 Os signatures of pyroxenites and the core mantle interaction debate.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 35, abstract only.MantleGeochronology
DS200612-1059
2006
Pearson, D.G.Pearson, D.G., Harris, J.W.Diamond geochronology - a record of continental lithosphere evolution.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 13. abstract only.MantleGeochronology
DS200712-0550
2007
Pearson, D.G.Klein Ben-David, O., Pearson, D.G.Sr isotopes and trace element pattern in sub-calcic garnets: a perspective on diamond bearing fluids.Plates, Plumes, and Paradigms, 1p. abstract p. A490.Canada, Northwest TerritoriesEkati
DS200712-0749
2007
Pearson, D.G.Morel, M.L.A., Pearson, D.G., Luguiet, A., Davies, G.R.Os isotopic and PGE evidence for major disruption and addition to the lithospheric mantle: a study of peridotites from the Premier Mine, Kaapvaal Craton. SAPlates, Plumes, and Paradigms, 1p. abstract p. A687.Africa, South AfricaPremier
DS200712-0806
2007
Pearson, D.G.Parman, S.W., Pearson, D.G., Nowell, G.M.The hidden history of mantle depletion: Os isotopes reveal a link between mantle depletion and crustal growth.Plates, Plumes, and Paradigms, 1p. abstract p. A757.MantlePulsed growth
DS200712-0821
2007
Pearson, D.G.Pearson, D.G., Harlou, R., Hayman, P., Cartigny, P., Kopylova, M.Sr isotopic compositions of ultra deep inclusions in diamonds: implications for mantle chemical structure and evolution.Plates, Plumes, and Paradigms, 1p. abstract p. A769.MantleUHP
DS200712-0822
2007
Pearson, D.G.Pearson, D.G., Parman, S.W., Nowell, G.M.A link between large mantle melting events and continent growth seen in osmium isotopes.Nature, Vol. 449, Sept. 13, ppp. 202-205.MantleGeochronology, melting
DS200712-0990
2007
Pearson, D.G.Simon, N.S.C., Carlson, R.W., Pearson, D.G., Davies, G.R.The origin and evolution of the Kaapvaal Cratonic lithospheric mantle.Journal of Petrology, Vol. 48, 3, pp. 589-625.Africa, South AfricaTectonics
DS200812-0225
2008
Pearson, D.G.Coe, N., Le Roex, A., Gurney, J., Pearson, D.G., Nowell, G.Petrogenesis of the Swartruggens and Star Group II kimberlite dyke swarms, South Africa: constraints from whole rock geochemistry.Contributions to Mineralogy and Petrology, Vol. 156, pp. 627-652.Africa, South AfricaKaapvaal Craton, petrogenesis
DS200812-0226
2008
Pearson, D.G.Coe, N., Roex, A., Gurney, J., Pearson, D.G., Nowell, G.Petrogenesis of the Swartuggens and Star Group II kimberlite dyke swarms, South Africa: constraints from whole rock geochemistry.Contributions to Mineralogy and Petrology, Vol. 156, 5, pp. 627-652.Africa, South AfricaDeposit - Swartruggens and Star
DS200812-0577
2008
Pearson, D.G.Kjarsgaard, B.A., Pearson, D.G., Tappe, S., Nowell, G.M., Dowall, D.P.Kimberlites: high H2O/CO2, MgO rich and K poor silica undersaturated magmas. Lac de Gras9IKC.com, 3p. extended abstractAfrica, South Africa, Canada, Northwest TerritoriesGroup 1 kimberlites
DS200812-0580
2008
Pearson, D.G.Klein-Ben David, O., Pearson, D.G., Nowell, G.M., Ottley, C., Cantigny, P.Origins of diamond forming fluids - constraints from a coupled Sr Nd Pb isotope and trace element approach.Goldschmidt Conference 2008, Abstract p.A479.TechnologyMicro-inclusions
DS200812-0589
2008
Pearson, D.G.Kopylova, M.G., Nowell, G.M., Pearson, D.G., Markovic, G.Crystallization of megacrysts from kimberlites: geochemical evidence from high Cr megacrysts in the Jericho kimberlite.9IKC.com, 3p. extended abstractCanada, NunavutDeposit - Jericho
DS200812-0639
2008
Pearson, D.G.Le Roex, A., Coe, N., Gurney, J., Pearson, D.G., Nowell, G.Petrogenesis of Group II kimberlites: a case study from southern Africa.9IKC.com, 3p. extended abstractAfrica, South Africa, BotswanaDeposit - Swartruggens, Star
DS200812-0704
2008
Pearson, D.G.Malarkey, J., Pearson, D.G., Davidson, J.P., Wiitig, N.Origins of Cr diopside in peridotite xenoliths.Goldschmidt Conference 2008, Abstract p.A588.Europe, Greenland, Africa, South AfricaDeposit - Kimberley
DS200812-0804
2008
Pearson, D.G.Nowell, G.M., Pearson, D.G., Irving, A.J.Lu Hf and Re Os isotope studies of lamproite genesis.9IKC.com, 3p. extended abstractUnited States, Australia, CanadaLamproite - geochronology
DS200812-0867
2008
Pearson, D.G.Pearson, D.G., Kjarsgaard, B.A., Garrido, C., Nixon, P.H.The Ronda peridotite and lamproites in Spain. Salmeron, Jumill, Cerro Canbezo Maria. Chemical analyses of lamproite/ Isotopic systematics of lamproites.9th. IKC Field Trip Guidebook, CD 38p.Europe, SpainGuidebook - lamproites
DS200812-0868
2008
Pearson, D.G.Pearson, D.G., Nowell, G.M., Kjarsgaard, B.A., Dowall, D.P.The genesis of kimberlite: geochemical constraints.9IKC.com, 3p. extended abstractCanada, Northwest TerritoriesDeposit - Lac de Gras geochemistry
DS200812-0869
2008
Pearson, D.G.Pearson, D.G., Nowell, G.M., Klein Ben-David, O., Kjarsgaard, B.A.,Irving, A.J.Isotopic constraints on the source regions of alkaline volcanics.Goldschmidt Conference 2008, Abstract p.A731.MantleLamproite, Group I kimberlites, geochronology
DS200812-0870
2008
Pearson, D.G.Pearson, D.G., Wittig, N.Formation of Archean continental lithosphere and its diamonds: the root of the problem.Journal of the Geological Society, Vol. 165, pp. 895-914.MantleDiamond genesis - review
DS200812-0971
2008
Pearson, D.G.Rosenthal, A., Foley, S.F., Pearson, D.G., Nowell, G.M., Tappe, S.Origin of kamafugite magmas in the East African Rift of western Uganda.9IKC.com, 3p. extended abstractAfrica, UgandaToro Ankole volcanic field
DS200812-1060
2008
Pearson, D.G.Shirey, S.B., Richardson, S.H., Pearson, D.G., Carlson, R.W., Harris, J.W.Eclogitic sulfide and silicate inclusions in diamonds and subcontinental geological processes.Goldschmidt Conference 2008, Abstract p.A862.Africa, Botswana, South AfricaDeposit - Jwaneng, Koffiefontein, Orapa, Premier,Venetia
DS200812-1179
2008
Pearson, D.G.Tomlinson, E.I., Muller, W., Hinton, R.W., Klein Ben-David, O., Pearson, D.G., Harris, J.W.Metasomatic processes recorded in fibrous diamonds.Goldschmidt Conference 2008, Abstract p.A950.Canada, Northwest TerritoriesDeposit - Panda
DS200812-1259
2008
Pearson, D.G.Wittig, N., Pearson, D.G., Webb, M., Ottley, C.J., Irvine, G.J., Kopylova, M., Jensen, S.M., Nowell, G.M.Origin of cratonic lithospheric mantle roots: a geochemical study of peridotites from the North Atlantic Craton, West Greenland.Earth and Planetary Science Letters, In press available, 83p.Europe, GreenlandGeochemistry
DS200812-1260
2008
Pearson, D.G.Wittig, N., Pearson, D.G., Webb, M., Ottley, C.J., Irvine, G.J., Kopylova, M., Jensen, S.M., Nowell, G.M.Origin of cratonic lithospheric mantle roots: a geochemical study of peridotites from the North Atlantic craton, West Greenland.Earth and Planetary Science Letters, Vol. 274, 1-2, pp. 24-33.Europe, GreenlandGeochemistry
DS200812-1261
2008
Pearson, D.G.Wittig, N., Webb, M.,Pearson, D.G., Dale, C.W., Ottley, C.J., Luguet, A., Jensen, S.M.Lithosphere stabilization ages beneath sw Greenland.Goldschmidt Conference 2008, Abstract p.A1030.Europe, GreenlandNorth Atlantic Craton, kimberlites
DS200912-0143
2009
Pearson, D.G.Dale, C.W., Pearson, D.G., Starkey, N.A., Stuart, F.M., Ellam, Larsen, Fitton, MacPhersonOsmium isotope insights into high 3He4He mantle and convecting mantle in the North Atlantic.Goldschmidt Conference 2009, p. A260 Abstract.Canada, Nunavut, Baffin Island, Europe, GreenlandPicrite
DS200912-0144
2009
Pearson, D.G.Dale, C.W., Pearson, D.G., Starkey, N.A., Stuart, F.M., Ellam, R.M., Larsen, L.M., Fitton, J.G., Grousset, F.E.Osmium isotopes in Baffin Island and West Greenland picrites: implications for the 187 Os and 188 Os composition of the convection mantle and nature 3He/4heEarth and Planetary Interiors, Vol. 278, 3-4, pp. 267-277.MantleConvection
DS200912-0161
2009
Pearson, D.G.Day, J.M.D., Pearson, D.G., Macpherson, C.G., Lowry, D., Carracedo, J-C.Pyroxenite rich mantle formed by recycled oceanic lithosphere: oxygen osmium isotope evidence from Canary Island lavas.Geology, Vol. 37, 6, pp. 555-558.Mantle, Canary IslandsGeochronology
DS200912-0281
2009
Pearson, D.G.Harlou, R., Pearson, D.G., Nowell, G.M., Ottley, C.J., Davidson, J.P.Combined Sr isotope and trace element analysis of melt inclusions at sub-ng levels using micro-milling, TIMS and ICPMS.Chemical Geology, Vol. 260, 3-4, pp. 254-268.TechnologyGeochronology
DS200912-0330
2009
Pearson, D.G.Ishikawa, A., Pearson, D.G., Dale, C.W.Re Os isotopes and platinum group elements in a peridotite pyroxenite hydrid mantle.Goldschmidt Conference 2009, p. A572 Abstract.MantleMagmatism
DS200912-0385
2009
Pearson, D.G.Kjarsgaard, B.A., Pearson, D.G., Tappe, S., Nowell, G.M., Dowall, D.P.Geochemistry of hypabyssal kimberlites from Lac de Gras Canada: comparisons to global database and implications to the parent magma problem.Lithos, In press available, 49p.Canada, Northwest TerritoriesGeochemical - whole rock database
DS200912-0388
2009
Pearson, D.G.Klein-BenDavid, O., Pearson, D.G.Origins of subcalcic garnets and their relation to diamond forming fluids - case studies from Ekati (NWT-Canada) and Murowa ( Zimbabwe).Geochimica et Cosmochimica Acta, Vol. 73, pp. 837-855.Canada, Northwest Territories, Africa, ZimbabweDeposit - Ekati, Murowa
DS200912-0405
2009
Pearson, D.G.Kopylova, M.G., Nowell, G.M., Pearson, D.G., Markovic, G.Crystallization of megacrysts from protokimberlitic fluids: geochemical evidence from high - Cr megacrysts in the Jericho kimberlite.Lithos, In press - available 51p.Canada, NunavutDeposit - Jericho
DS200912-0422
2009
Pearson, D.G.Laiginhas, F., Pearson, D.G., Phillips, D., Burgess, R., Harris, J.W.Re Os and 40Ar 39Ar isotope measurements of inclusions in alluvial diamonds from the Ural Mountains: constraints on diamond genesis and eruption ages.Lithos, in press availableRussia, UralsGeochronology
DS200912-0459
2009
Pearson, D.G.Luguet, A., Jaques, A.I., Pearson, D.G., Smith, C.B., Bulanova, G.P., Roffey, S.L., Rayner, M.J., Lorand, J.P.An integrated petrological, geochemical and Re-Os isotope study of peridotite xenoliths from the Argyle lamproite, western Australia and implications forLithos, In press available, 64p.AustraliaGeochronology - Cratonic diamond occurrences
DS200912-0467
2009
Pearson, D.G.Malarkey, J., Pearson, D.G., Davidson, J.P., Nowell, G.M., Kjarsgaard, B., Ottley, C.J.Geochemical dissection of a kimberlite: What makes up a whole rock analysis?Goldschmidt Conference 2009, p. A820 Abstract.Canada, Nunavut, Somerset IslandDeposit - Jos
DS200912-0468
2009
Pearson, D.G.Malarkey, J., Pearson, D.G., Davidson, J.P., Nowell, G.M., Kjarsgaard, B., Ottley, C.J.Geochemical discretion of a kimberlite: what makes a whole rock analysis?GAC/MAC/AGU Meeting held May 23-27 Toronto, Abstract onlyTechnologyGeochronology
DS200912-0481
2009
Pearson, D.G.Mather, K.A., Pearson, D.G., Kjarsgaard, B.A., Stachel, T.A new look at Slave lithosphere paleogeotherms and the 'diamond window'.37th. Annual Yellowknife Geoscience Forum, Abstracts p. 42-3.Canada, Northwest TerritoriesGeothermometry
DS200912-0491
2009
Pearson, D.G.McNeill, J.C., Klein-BenDavid, O., Pearson, D.G., Nowell, D.G., Ottley, C.J., Chinn, I., Malarkey, J.Quantitative analysis of trace element impurity levels in some gem-quality diamonds.GAC/MAC/AGU Meeting held May 23-27 Toronto, Abstract onlyTechnologyDiamond inclusions
DS200912-0661
2009
Pearson, D.G.Sand, K.K., Waight, T.E., Pearson, D.G., Nielsen, T.F.D., Makovicky, E., Hutchison, M.T.The lithospheric mantle below southern West Greenland: a geothermobarometric approach to diamond potential and mantle stratigraphy.Lithos, In press availableEurope, GreenlandDiamond prospectivity, geothermometry
DS200912-0702
2009
Pearson, D.G.Smith, C.B., Bulanova, G.P., Kohn, S.C., Milledge, H.J., Hall, A.E., Griffin, B.J., Pearson, D.G.Nature and genesis of Kalimantan diamonds.Lithos, In press available, 38p.Indonesia, KalimantanAlluvials, diamond morphology
DS200912-0703
2009
Pearson, D.G.Smith, C.B., Pearson, D.G., Bulanova, G.P., Beard, A.D., Carlson, R.W., Wittig, N., Sims, K., Chimuka, L., Muchemwa, E.Extremely depleted lithospheric mantle and diamonds beneath the southern Zimbabwe Craton.Lithos, In press available, 41p.Africa, ZimbabweDeposit - Murowa, Sese
DS200912-0807
2009
Pearson, D.G.Wasch, L.J., Van der Zwan, F.M., Nebel, O., Morel, M.L.A., Hellebrand, E.W.G., Pearson, D.G., Davies, G.R.An alternative model for silica enrichment in the Kaapvaal subcontinental lithospheric mantle.Geochimica et Cosmochimica Acta, Vol. 73, 22, pp. 6894-6917.MantleMelting
DS200912-0821
2009
Pearson, D.G.Wittig, N., Pearson, D.G., Downes, H., Baker, J.A.The U, Th and Pb elemental and isotope compositions of mantle clinopyroxenes and their grain boundary contamination derived from leaching and digestion experiments.Geochimica et Cosmochimica Acta, Vol. 73, 2, pp. 469-488.MantleGeochronology
DS201012-0088
2010
Pearson, D.G.Carlson, R., Pearson, D.G.The formation and evolution of continental lithospheric mantle. Keynote paperGoldschmidt 2010 abstracts, abstractMantleReview
DS201012-0274
2010
Pearson, D.G.Heaman, L.M., Pearson, D.G.Nature and evolution of the Slave Province subcontinental lithospheric mantle.Canadian Journal of Earth Sciences, Vol. 47, 4, pp. 369-388.Canada, Northwest TerritoriesGeophysics - seismic
DS201012-0322
2010
Pearson, D.G.Janney, P.E., Shirey, S.B., Carlson, R.W., Pearson, D.G., Bell, D.R., Le Roex, A., Ishikawa, Nixon, BoydAge, composition and thermal characteristics of South African off craton mantle lithosphere: evidence for a multi stage history.Journal of Petrology, Vol. 51, 9, pp. 1849-1890,Africa, South AfricaGeochronology, geothermometry
DS201012-0393
2010
Pearson, D.G.Klein Ben-David, O., Pearson, D.G., Nowell, G.M., Ottley, C., McNeill, J.C.R., Cartigny, P.Mixed fluid sources involved in diamond growth constrained by Sr-Nd-Pb-C-N- isotopes and trace elements.Earth and Planetary Science Letters, Vol. 289, pp. 123-133.MantleMagmatism, fibrous diamonds
DS201012-0469
2010
Pearson, D.G.Malarkey, J., Pearson, D.G., Kjarsgaard, B.A., Davidson, J.P., Nowell, G.M., Ottley, C.J., Stammer, J.From source to crust: tracing magmatic evolution in a kimberlite and a melilitite using microsample geochemistry.Earth and Planetary Science Letters, Vol. 299, 1-2, Oct. 15, pp. 80-90.Canada, Northwest Territories, Africa, South AfricaGeochemistry - JOS
DS201012-0476
2010
Pearson, D.G.Mather, K.A., Pearson, D.G., Kjarsgaard, B.A., Jackson, S.Understanding the lithosphere beneath Arctic Canada - an example from the N. Slave craton.38th. Geoscience Forum Northwest Territories, Abstract p. 65.Canada, Northwest TerritoriesDeposit - Artemisia
DS201012-0621
2010
Pearson, D.G.Rehfeldt, T., Foley, S.F., Jacob, D.E., Pearson, D.G.Trace elements in mantle olivine and orthopyroxene from the North Atlantic and Kaapvaal Cratons.Goldschmidt 2010 abstracts, abstractAfrica, South Africa, EuropeGeochemistry
DS201012-0779
2010
Pearson, D.G.Tappe, S., Pearson, D.G., Heaman, L., Nowell, G., Milstead, P.Relative roles of cratonic lithosphere and asthenosphere in controlling kimberlitic magma compositions: Sr Nd Hf isotope evidence fromGoldschmidt 2010 abstracts, abstractEurope, Greenland, Canada, LabradorGeochronology
DS201012-0848
2010
Pearson, D.G.Wiggers de Vries, D.F., Drury, M.R., De Winter, D.A.M., Bulanova, G.P., Pearson, D.G., Davies, G.R.Three dimensional cathodluminescence imaging and electron backscatter diffraction: tools for studying the genetic nature of diamond inclusions.Contributions to Mineralogy and Petrology, in press available, 15p.TechnologyDiamond inclusions
DS201012-0854
2010
Pearson, D.G.Wittig, N., Webb, M., Pearson, D.G., Dale, C.W., Ottley, C.J., Hutchison, M., Jensen, S.M., Luget, A.Formation of the North Atlantic craton: timing and mechanisms constrained from Re-Os isotope and PGE dat a of peridotite xenoliths from S.W. Greenland.Chemical Geology, Vol. 276, 3-4, pp. 166-187.Europe, GreenlandCraton
DS201012-0855
2010
Pearson, D.G.Wittig, N., Webb, M., Pearson, D.G., Dale, C.W., Ottley, C.J., Hutchison, M., Jensen, S.M., Luget, A.Formation of the North Atlantic craton: timing and mechanisms constrained from Re-Os isotope and PGE dat a of peridotite xenoliths from S.W. Greenland.Chemical Geology, Vol. 276, 3-4, pp. 166-187.Europe, GreenlandCraton
DS201112-0111
2011
Pearson, D.G.Brin, L.E., Pearson, D.G., Riches, A.J.V., Miskovic, A., Kjarsgaard, B.A., Kienlen, B., Reford, S.W.Evaluating the northerly extent of the Slave Craton in the Canadian Arctic.Yellowknife Geoscience Forum Abstracts for 2011, Poster abstract p. 95.Canada, Northwest Territories, Nunavut, Victoria Island, Parry PeninsulaKimberlite borne - xenoliths -
DS201112-0231
2011
Pearson, D.G.Wiggers de Vries, D.F., Drury, M.R., de Winter, D.A.M., Bulanova, G.P., Pearson, D.G., Davies, G.R.Three dimensional cathodluminescence imaging and electron backscatter diffraction: tools for studying the genetic nature of diamond inclusions.Contributions to Mineralogy and Petrology, Vol. 161, 4, pp. 565-579.RussiaDeposit - Udachnaya
DS201112-0625
2011
Pearson, D.G.Luget, A., Behrens, M., Herwartz, D., Pearson, D.G.Re-Os and Lu-Hf dating in Letlhakane peridotite xenoliths ( Botswana).Goldschmidt Conference 2011, abstract p.1365.Africa, BotswanaGeochronology, Magondi Belt
DS201112-0633
2011
Pearson, D.G.Malarkey, J., Wittig, N., Pearson, D.G., Davidson, J.P.Characterising modal metasomatic processes in young continental lithospheric mantle: a microsampling isotopic and trace element study on xenoliths from the Middle Atlas Mountains, Morocco.Contributions to Mineralogy and Petrology, Vol. 162, 2, pp. 289-302.Europe, Africa, MoroccoMetasomatism
DS201112-0634
2011
Pearson, D.G.Malarkey, J., Wittig, N., Pearson, D.G., Davidson, J.P.Characterising modal metasomatic processes in young continental lithospheric mantle: a microsampling isotopic and trace element study on xenoliths ...Contributions to Mineralogy and Petrology, in press, availableAfrica, MoroccoMetasomatism - Middle Atlas Mountains
DS201112-0654
2011
Pearson, D.G.Mather, K.A., Pearson, D.G., McKenzie, D., Kjarsgaard, B.A., Priestley, K.Constraints on the depth and thermal history of cratonic lithosphere from peridotite xenoliths, xenocrysts and seismology.Lithos, Vol. 125, pp. 729-742.Africa, South Africa, Canada, Somerset IslandGeothermometry, geophysics - seismics
DS201112-0684
2011
Pearson, D.G.Miskovic, A., Ickert, R.B., Pearson, D.G., Stern, R.A.Oxygen isotope survey of the Northern Canadian lithospheric mantle: implications for the evolution of cratonic roots.Yellowknife Geoscience Forum Abstracts for 2011, abstract p. 64-65.Canada, Northwest TerritoriesSCLM - geodynamics
DS201112-0773
2011
Pearson, D.G.Pearson, D.G., Kjarsgaard, B.A.Diamonds and the mantle lithosphere in northern Canada.PDAC 2011, 1/2p. abstractCanada, Northwest TerritoriesGeochronology
DS201112-0774
2011
Pearson, D.G.Pearson, D.G., Tappe, S., Smart, K.A., Mather, K.S., Dale, C.W., Kjarsgaard, B.A.Crust mantle links in cratons.Goldschmidt Conference 2011, abstract p.1610.MantleSlave, Kaapvaal, coupling -decoupling
DS201112-0862
2011
Pearson, D.G.Riches, A.J.V., Pearson, D.G., Kjarsgaard, B.A., Jackson, S.E., Stachel, T., Armstrong, J.P.Deep lithosphere beneath the Rae Craton: peridotite xenoliths from Repulse Bay, Nunavut.Yellowknife Geoscience Forum Abstracts for 2011, abstract p. 74-75.Canada, Nunavut, Victoria Island, Parry PeninsulaMineralogy
DS201112-1028
2011
Pearson, D.G.Tappe, S., Pearson, D.G., Nowell, G., Nielsen, T., Milstead, P., Muehlenbachs, K.A fresh isotopic look at Greenland kimberlites: craton mantle lithosphere imprint on deep source signal.Earth and Planetary Science Letters, Vol. 305, 1-2, pp. 235-248.Europe, GreenlandGeochronology - convection
DS201112-1029
2011
Pearson, D.G.Tappe, S., Smart, K.A., Pearson, D.G., Steenfelt, A., Simonetti, A.Craton formation in late Archean subduction zones revealed by first Greenland eclogites.Geology, Vol. 39, 12, pp. 1103-1106.Europe, GreenlandMelting , Nunatak-1390
DS201212-0097
2012
Pearson, D.G.Bulanova, G.P., Wiggers de Vries, D.F., Beard, A., Pearson, D.G., Mikhail, S.S., Smelov, A.P., Davies, G.R.Two stage origin of eclogitic diamonds recorded by a single crystal from the Mir pipe, Yakutia.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractRussia, YakutiaDeposit - Mir
DS201212-0318
2012
Pearson, D.G.Hunt, L.,Stachel, T., Pearson, D.G., Jackson, S., McLean, H., Kjarsgaard, B.The origin of websterites at Diavik diamondmine, Canada, and the realationship to diamond growth.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractCanada, Northwest TerritoriesDeposit - Diavik
DS201212-0324
2012
Pearson, D.G.Hutchison, M.T., Dale, C.W., Nowell, G.M., Pearson, D.G.Age constraints on ultra deep mantle petrology shown by Juin a diamonds.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractSouth America, BrazilDeposit - Juina
DS201212-0463
2012
Pearson, D.G.Melton, G.L., McNeill, J., Stachel, T., Pearson, D.G., Harris, J.W.Trace elements in gem diamond from Akwatia, Ghana and De Beers Pool, South Africa.Chemical Geology, Vol. 314-317, pp. 1-8.Africa, South Africa, GhanaDeposit - Akwatia, DeBeers Pool - Inclusions
DS201212-0538
2012
Pearson, D.G.Palot, M., Pearson, D.G., Stern, R., Stachel, T., Harris, J.W.Multiple growth events, processes and fluid sources involved in the growth of diamonds from Finsch mine, RSA: a micro-analytical study.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractAfrica, South AfricaDeposit - Finsch
DS201212-0546
2012
Pearson, D.G.Pearson, D.G., Mather, K.A., Ishikawa, A., Kjarsgaard, B.A.Origin and evolution of cratonic roots.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractGlobalCraton
DS201212-0585
2012
Pearson, D.G.Riches, A.J.V., Pearson, D.G., Stern, R.A., Ickert, R.B., Kjarsgaard, B.A., Jackson, S.E., Ishikawa, A.Multi-stage metasomatism of a Roberts Victor eclogite linked to the formation and destruction of diamond.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractAfrica, South AfricaDeposit - Roberts Victor
DS201212-0649
2012
Pearson, D.G.Shirey, S.B., Cartigny, P., Frost, D.J., Nestola, F., Nimis, P., Pearson, D.G., Sobolev, N.V., Walter, M.J.Diamonds and the geology of Earth mantle carbon.GSA Annual Meeting, Paper no. 211-5, abstractMantleSubduction
DS201212-0677
2012
Pearson, D.G.Smith, E.M., Kopylova, M.G., Nowell, G.M., Pearson, D.G., Ryder, J.Archean mantle fluids preserved in fibrous diamonds from Wawa, Superior Craton.Geology, Vol. 40, Dec. pp. 1071-74.Canada, OntarioDeposit - Wawa
DS201212-0678
2012
Pearson, D.G.Smith, E.M., Kopylova, M.G., Nowell, G.M., Pearson, D.G., Ryder, J., Afanasev, V.P.D., Beeby, A.The contrast in trace element chemistry and volatile composition between fluid inclusions n fibrous and octahedral diamonds.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractCanada, Ontario, WawaDiamond inclusions
DS201212-0679
2012
Pearson, D.G.Smith, E.M., Kopylova, M.G., Nowell, G.M., Pearson, D.G., Ryder, J., Afanasiev, V.P.The contrast in trace element chemistry and volatile composition between fluid inclusions in fibrous and octahedral diamonds.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractCanada, Ontario, WawaDiamond - inclusions
DS201212-0778
2012
Pearson, D.G.Wiggers de Vries, D.F., Harris, J.W., Pearson, D.G., Davies, G.R.Re-Os isotope constraints on the ages of diamonds from Mwadui, Tanzania.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractAfrica, TanzaniaDeposit - Mwadui
DS201312-0093
2013
Pearson, D.G.Bragagni, A., Luguet, A., Pearson, D.G., Fonseca, R.O.C., Kjarsgaard, B.A.Insight on formation and evolution of cratonic mantle: Re-Os dating of single sulfides from Somerset mantle xenoliths ( Rae Craton) Canada.Goldschmidt 2013, AbstractCanada, NunavutGeochronolgy
DS201312-0410
2013
Pearson, D.G.Hunt, L., Stachel, T., Pearson, D.G., Stern, R., Muehlenbachs, K., McLean, H.Multi-stage evolution of non-gem diamonds at the Diavik diamond mine, Canada.GAC-MAC 2013 SS4: Diamond: from birth in the mantle to emplacement in kimberlite, abstract onlyCanada, Northwest TerritoriesDeposit - Diavik
DS201312-0411
2013
Pearson, D.G.Hunt, L., Stachel, T., Pearson, D.G., Stern, R., Muehlenbachs, K., McLean, H.The complex growth of non-gem diamonds at the Diavik diamond mine, Canada.Geoscience Forum 40 NWT, abstract only p. 19Canada, Northwest TerritoriesDiamond morphology
DS201312-0489
2013
Pearson, D.G.Klein-BenDavid, O., Pearson, D.G., Nowell, G.M., Ottley, C., McNeill, J.C.R., Logvinova, A., Sobolev, N.V.The sources and time integrated evolution of diamond forming fluid - trace elements and Sr isotopic evidence.Geochimica et Cosmochimica Acta, Vol. 125, pp. 146-169.Russia, Africa, Democratic Republic of Congo, Canada, Northwest TerritoriesFibrous diamonds, HDF, Diavik, Udachnaya
DS201312-0496
2014
Pearson, D.G.Konig, S., Lorand, J-P., Luguet, A., Pearson, D.G.A non primitive origin of near-chondritic S-Se-Te ratios in mantle peridotites; implications for the Earth's late accretionary history.Earth and Planetary Science Letters, Vol. 385, pp. 110-121.MantlePeridotite
DS201312-0516
2013
Pearson, D.G.Krebs, M.Y., Pearson, D.G., Stachel, T., Stern, R.A., Nowicki, T., Cairns, S.Variability in diamond population characteristics across the size range 0.2- 2-4 mm - a case study based on diamonds from Misery ( Ekati mine).2013 Yellowknife Geoscience Forum Abstracts, p. 34-35.Canada, Northwest TerritoriesDeposit - Misery
DS201312-0667
2013
Pearson, D.G.O'reilly, S., Griffin, W.L., Begg, G.C., Pearson, D.G., Hronsky, J.M.A.Archean lithospheric mantle: the fount of all ores?Goldschmidt 2013, AbstractMantleMagmatism
DS201312-0676
2013
Pearson, D.G.Palot, M., Pearson, D.G., Stachel, T.Multiple growth episodes or prolonged formation of diamonds? Inferences from infrared absorption data.Proceedings of the 10th. International Kimberlite Conference, Vol. 1, Special Issue of the Journal of the Geological Society of India,, Vol. 1, pp. 281-296.TechnologyDiamond morphology
DS201312-0677
2013
Pearson, D.G.Palot, M., Pearson, D.G., Stern, R.A., Stachel, T., Harris, J.W.Multiple growth events, processes and fluid sources involved in diamond genesis: a micro-analytical study of sulphide bearing diamonds from Finsch mine, RSA.Geochimica et Cosmochimica Acta, Vol. 106, pp. 51-70.Africa, South AfricaDeposit - Finsch
DS201312-0692
2013
Pearson, D.G.Pearson, D.G., Brin, L., Liu, J., Riches, A., Stachel, T., Mather, K.A., Kjarsgaard, B.A.Canada's Arctic cratons: how many, how old, how come?2013 Yellowknife Geoscience Forum Abstracts, p. 49-50.Canada, Northwest Territories, Nunavut, Victoria Island, Parry PeninsulaGeochronology - mantle peridotites
DS201312-0777
2013
Pearson, D.G.Sarkar, C., Heaman, L., Pearson, D.G.Detailed geochemical studies of Lac de Gras kimberlites - redefining the 'diamond age window'?Geoscience Forum 40 NWT, abstract only p. 43Canada, Northwest TerritoriesDeposit - Lac de gras ones
DS201312-0815
2012
Pearson, D.G.Shirey, S.B., Cartigny, P.,Frost, D.J., Nestola, F., Pearson, D.G., Sobolev, N.V., Walter, M.J.Diamonds and the geology of Earth mantle carbonGeological Society of America Annual Meeting abstract, Paper 211-5, 1/2p. AbstractMantleCarbon
DS201312-0816
2013
Pearson, D.G.Shirey, S.B., Cartigny, P., Frost, D.J., Keshav, S., Nestola, F., Nimis, P., Pearson, D.G., Sobolev, N.V., Walter, M.J.Diamonds and the geology of mantle carbon.Reviews in Mineralogy and Geochemistry, Vol. 75, pp. 355-421.MantleDiamond genesis
DS201312-0901
2013
Pearson, D.G.Tappe, S., Pearson, D.G., Kjarsgaard, B.A., Nowell, G., Dowall, D.Mantle transition zone input to kimberlite magmatism near a subduction zone: origin of anomalous Nd-Hf isotope systematics at Lac de Gras, Canada.Earth and Planetary Science Letters, Vol. 371-372, pp. 235-251.Canada, Northwest TerritoriesGeochronology, convection
DS201312-0903
2013
Pearson, D.G.Tappe, S., Pearson, D.G., Kjarsgaard, B.A., Nowell, G.M., Dowall, D.Linking kimberlite magmatism, transition zone diamonds, and subduction processes.Goldschmidt 2013, AbstractMantleSubduction
DS201312-0904
2013
Pearson, D.G.Tappe, S., Pearson, D.G., Prelevic, D.Kimberlite, carbonatite, and potassic magmatism as part of the geochemical cycle.Chemical Geology, Vol. 353, pp. 1-3 intro.MantleMelting, recyle
DS201312-0970
2013
Pearson, D.G.Wiggers de Vries, D.F., Pearson, D.G., Bulanova, G.P., Smelov, A.P., Pavlushin, A.D., Davies, G.R.Re-Os dating of sulphide inclusions zonally distributed in single Yakutian diamonds: evidence for multiple episodes of Proterozoic formation and protracted timescales of diamond growth.Geochimica et Cosmochimica Acta, Vol. 120, pp. 363-394.Russia, YakutiaDeposit - Mir, 23, Udachnaya
DS201412-0082
2014
Pearson, D.G.Bulanova, G.P., Wiggers de Vries, D.F., Pearson, D.G., Beard, A., Mikhail, S., Smelov, A.P., Davies, G.R.An eclogitic diamond from Mir pipe (Yakutia), recording two growth events from different isotopic sources.Chemical Geology, Vol. 381, pp. 40-54.Russia, YakutiaDeposit - Mir
DS201412-0086
2014
Pearson, D.G.Bussweiler, Y., Foley, S.F., Prelevic, D., Jacob, D.E., Pearson, D.G., Stachel, T.Olivine as a petrogenetic and exploration indicator in Lac de Gras kimberlites.2014 Yellowknife Geoscience Forum, p. 20, 21 abstractCanada, Northwest TerritoriesDeposit - Ekati
DS201412-0479
2014
Pearson, D.G.Krebs, M.Y., Pearson, D.G., Stachel, T., Stern, R.A., Nowicki, T., Cairns, S.Variability in diamond population characteristics across the size range 0.2-3.4 MM - a case study based on diamonds from Misery ( Ekati mine).Geological Society of America Conference Vancouver Oct. 19-22, 1p. AbstractCanada, Northwest TerritoriesDiavik mine - Misery
DS201412-0548
2014
Pearson, D.G.Marchesi, C., Dale, C.W., Garrdo, C.J., Pearson, D.G., Bosch, D., Bodinier, J-L., Gervilla, F., Hidas, K.Fractionation of highly siderophile elements in refertilized mantle: implications for the Os isotope composition of basalts.Earth and Planetary Science Letters, Vol. 400, pp. 33-44.MantleRonda peridotite
DS201412-0656
2014
Pearson, D.G.Palot, M., Pearson, D.G., Stern, R.A., Harris, J.W., Stachel, T.Fluid sources of ultradeep diamonds.2014 Yellowknife Geoscience Forum, p. 61, abstractAfrica, GuineaDeposit - Kankan
DS201412-0657
2014
Pearson, D.G.Palot, M., Pearson, D.G., Stern, R.A., Stachel, T., Harris, J.W.Isotopic constraints on the nature and circulation of deep mantle C-H-O-N fluids: Carbon and nitrogen systematics within ultra-deep diamonds from Kankan ( Guinea).Geochimica et Cosmochimica Acta, Vol. 139, pp. 26-46.Africa, GuineaDeposit - Kankan
DS201412-0667
1999
Pearson, D.G.Pearson, D.G.Evolution of cratonic lithospheric mantle: an isotopic perspective.Geochemical Society Special Publication No. 6, Mantle Petrology, No. 6, pp.MantleGeochronology
DS201412-0668
2014
Pearson, D.G.Pearson, D.G., Brenker, F., Nestola, F., McNeil, J., Nasdala, L., Hutchison, M., Mateev, S., Mather, K., Silversmit, G., Schmitz, S., Vekemans, B., Vinczw=e, L.A hydrous mantle transition zone indicated by ring woodite included within diamond.Goldschmidt Conference 2014, 1p. AbstractMantleDiamond inclusion
DS201412-0669
2014
Pearson, D.G.Pearson, D.G., Brenker, F.E., Nestola, F., McNeill, J., Nasdala, L., Hutchinson, M.T., Mateev, S., Mather, K., Silversmit, G., Schmitz, S., Vekemans, B., Vincze, L.Hydrous mantle transition zone indicated by ring woodite included in diamond.Nature, Vol. 507, March 13, pp. 221-224.Mantle, South America, Brazil, Mato GrossoDiamond inclusion - water storage capacity, magmatism
DS201412-0844
2014
Pearson, D.G.Smit, K.V., Pearson, D.G., Stachel, T., Seller, M.Peridotites from Attawapiskat, Canada: Mesoproterozoic reworking of Paleoarchean lithospheric mantle beneath the northern Superior Superterrane.Journal of Petrology, Vol. 55, 9, pp. 1829-1863.Canada, Ontario, AttawapiskatDeposit - Victor arena
DS201412-0959
2014
Pearson, D.G.Wang, H., Van Hunen, J., Pearson, D.G., Allen, M.B.Craton stability and longevity: the roles of composition- dependent rheology and buoyancy.Earth and Planetary Science Letters, Vol. 391, 1, pp. 224-233.MantleCraton
DS201504-0215
2015
Pearson, D.G.Sarkar, C., Heaman, L.M., Pearson, D.G.Duration and periodicity of kimberlite volcanic activity in the Lac de Gras kimberlite field, Canada and some recommendations for kimberlite geochronology.Lithos, Vol. 218-219, pp. 155-166.Canada, Northwest TerritoriesDeposit - Eddie
DS201507-0322
2015
Pearson, D.G.Liu, J., Scott, J.M., Martin, C.E., Pearson, D.G.The longevity of Archean mantle residues in the convecting upper mantle and their role in young continent formation.Earth and Planetary Science Letters, Vol. 424, pp. 109-118.MantleConvection
DS201508-0367
2015
Pearson, D.G.Luguet, A., Behrens, M., Pearson, D.G., Konig, S., Herwartz, D.Significance of the whole rock Re-Os ages in cryptically and modally metasomatized cratonic peridotites: constraints from HSE-Se-Te systematics.Geochimica et Cosmochimica Acta, Vol. 164, pp. 441-463.Africa, BotswanaDeposit - Letlhakane
DS201509-0435
2015
Pearson, D.G.Wainwright, A.N., Luguet, A., Fonsec, R.O.C., Pearson, D.G.Investigating metasomatic effects on the 187Os isotopic signature: a case study on the micrometric base metal sulphides in metasomatised peridotite from the Letlhakane kimberlite, (Botswana). Lithos, Vol. 232, pp. 35-48.Africa, BotswanaDeposit - Letlhakane

Abstract: The peridotite xenoliths of the Letlhakane kimberlite (Botswana), which intrude the Proterozoic Magondi Belt on the western margin of the Zimbabwe craton, represent highly depleted melting residues. These residues suffered subsequent variable metasomatic overprinting, evidenced by cryptic trace element enrichments in the spinel peridotites to modal addition of phlogopite, clinopyroxene and spinel within the garnet peridotites. In order to assess the robustness of the Re–Os chronometer in such highly metasomatised peridotites, detailed investigations of base metal sulphide (BMS) petrography and single-BMS grain 187Os/188Os analyses have been undertaken in three representative peridotites.
DS201509-0437
2015
Pearson, D.G.Weiss, Y., McNeill, J., Pearson, D.G., Ottley, C.J.Highly saline fluids from a subducting slab as the source for fluid-rich diamonds.Nature, Vol. 524, pp. 339-342.MantleSubduction

Abstract: The infiltration of fluids into continental lithospheric mantle is a key mechanism for controlling abrupt changes in the chemical and physical properties of the lithospheric root1, 2, as well as diamond formation3, yet the origin and composition of the fluids involved are still poorly constrained. Such fluids are trapped within diamonds when they form4, 5, 6, 7 and so diamonds provide a unique means of directly characterizing the fluids that percolate through the deep continental lithospheric mantle. Here we show a clear chemical evolutionary trend, identifying saline fluids as parental to silicic and carbonatitic deep mantle melts, in diamonds from the Northwest Territories, Canada. Fluid–rock interaction along with in situ melting cause compositional transitions, as the saline fluids traverse mixed peridotite–eclogite lithosphere. Moreover, the chemistry of the parental saline fluids—especially their strontium isotopic compositions—and the timing of host diamond formation suggest that a subducting Mesozoic plate under western North America is the source of the fluids. Our results imply a strong association between subduction, mantle metasomatism and fluid-rich diamond formation, emphasizing the importance of subduction-derived fluids in affecting the composition of the deep lithospheric mantle.
DS201512-1926
2015
Pearson, D.G.Hardman, M.F., Stachel, T., Pearson, D.G., Kinakin, Y.B., Bellinger, J.Improving the utility of eclogitic garnet in diamond exploration - examples from Lac de Gras and worldwide localities.43rd Annual Yellowknife Geoscience Forum Abstracts, abstract p. 47.Canada, Northwest TerritoriesGarnet chemistry

Abstract: In diamond exploration, the use of compositional data to identify diamond-related peridotitic xenocrysts has long been a widely used and powerful tool. In contrast, the application of similar methods to eclogitic garnet chemistry remains a challenge. The inability to unequivocally classify certain “eclogitic” garnet compositions as either mantle- or crust-derived implies that a high abundance of lower-crustal garnets will increase diamond-exploration expenditures by introducing a number of “false positives.” Revising existing classification schemes (e.g., Schulze, 2003) to reduce the abundance of “false positives” may, however, increase the number of “false negatives” through the misclassification of mantle-derived garnets as crustal. This study presents new geochemical and petrographical data for garnet and clinopyroxene from 724 kimberlite-hosted, crust- and mantle-derived xenoliths from localities worldwide, with a focus on samples whose lithology is constrained petrographically, rather than single mineral grains from concentrate. Mantle samples are primarily eclogitic and pyroxenitic, as constrained by mineral assemblage and garnet and clinopyroxene mineral chemistry, while crustal samples are dominantly plagioclase-bearing garnet-granulites. For those localities where an established geothermal gradient is available from literature resources, garnet-clinopyroxene pairs are employed in the estimation of pressure-temperature conditions of equilibration through the iterative coupling of the Krogh (1988) geothermometer and the relevant geothermal gradient. Our preliminary results suggest that closure temperatures for Fe-Mg exchange exceed the temperatures of residence of many lower-crustal samples, as geotherm-based calculated pressures of equilibration exceed the apparent stability of plagioclase (see Green and Ringwood, 1972). Comparison of equilibration pressures with sodium contents in garnet for mantle-derived samples (the diamond-facies criterion of Gurney, 1984) shows a positive correlation at localities for which an adequate range of pressures is observed (e.g., the Diavik mine). Other populations, such as mantle eclogitic garnets from Roberts Victor, plot at a much more restricted range of pressures and hence fail to demonstrate this correlation; instead, these samples may reflect the influence of a broader range of bulk-compositions, providing varying amounts of sodium to their constituent garnets. The results presented here demonstrate clearly that garnets from mantle- and crust-derived samples show significant overlap in geochemical character, for example in garnet Ca# vs. Mg# space (discrimination diagram of Schulze, 2003), where approximately 66% of our crust-derived garnet analyses plot in the “mantle” field. This percentage varies among locations. A selection of particularly high-Mg#, low-Ca# garnets derived from crustal, plagioclase-bearing lithologies in this study highlights the potential for crust-mantle confusion, as these garnets have Mg# in-excess of many mantle-derived eclogitic/pyroxenitic garnets. As a consequence, Fe-Mg-Ca-based classifications alone cannot reliably discriminate mantle and crustal garnets. The next step in this project will be to obtain trace element data for the entire sample suite. This will allow us to test the Li-geobarometer of Hanrahan et al. (2009) for eclogites and to search for trace element signatures that can be used as robust indicators of a diamond-facies origin of eclogitic garnets. Trace element data will also be employed in the refinement of the crust/mantle division discussed above.
DS201512-1986
2015
Pearson, D.G.Weiss, Y., Pearson, D.G., Mcneill, J., Nowell, G.M., Ottley, C.J.Salty fluids, subducted slabs and NWT diamonds.43rd Annual Yellowknife Geoscience Forum Abstracts, abstract p. 108.Canada, Northwest TerritoriesDiamond genesis

Abstract: Diamonds from the Ekati and Diavik mines have provided a wealth of information on diamond forming processes beneath the Slave craton. Fluid-rich “fibrous” diamonds trap some of the fluid from which the diamond is growing and hence provide a unique means to characterize directly the fluids that percolate through the deep continental lithospheric mantle. On a world-wide basis, Ekatic and Diavik fluid-rich diamonds trap an anomalously high proportion of fuids that are “salty” or high saline in composition, with high Na and Cl contents. The origin of these “salty” fluids has been something of a mystery. Here we show the first clear chemical evolutionary trend identifying saline fluids as parental to silicic and carbonatitic deep mantle melts, in diamonds from the Northwest Territories, Canada. Fluid-rock interaction along with in-situ melting cause compositional transitions, as the saline fluids traverse mixed peridotite-eclogite lithosphere. Moreover, the chemistry of the parental saline fluids - especially their Sr isotopic compositions - and the timing of host diamond formation suggest a subducting Mesozoic plate under western North America to be the source of the fluids. Our results imply a strong association between subduction, mantle metasomatism and fluid-rich diamond formation, emphasizing the importance of subduction-derived fluids in impacting the composition of the deep lithospheric mantle
DS201601-0028
2016
Pearson, D.G.Liu, J., Riches, A.J.V., Pearson, D.G., Luo, Y., Kienlen, B., Kjarsgaard, B.A., Stachel, T., Armstrong, J.P.Age and evolution of the deep continental root beneath the central Rae craton, northern Canada.Precambrian Research, Vol. 272, pp. 168-174.CanadaGeocronology, metasomatism, tectonics

Abstract: Canada is host to at least six separate cratons that comprise a significant proportion of its crustal extent. Of these cratons, we possess knowledge of the cratonic lithospheric roots beneath only the Slave craton and, to a lesser extent, the Superior craton, despite the discovery of many new diamond-bearing kimberlites in Canada's North. Here we present the first age, composition and geothermal information for kimberlite-borne peridotite xenoliths from two localities within the central Rae craton: Pelly Bay and Repulse Bay. Our aim is to investigate the nature and evolution of the deep lithosphere in these regions and to examine how events recorded in the mantle may or may not correlate with the complex history of crustal evolution across the craton. Peridotite xenoliths are commonly altered by secondary processes including serpentinization, silicification and carbonation, which have variably affected the major element compositions. These secondary processes, as well as mantle metasomatism recorded in pristine silicate minerals, however, did not significantly modify the relative compositions of platinum-group elements (PGE) and Os isotope ratios in the majority of our samples from Pelly Bay and Repulse Bay, as indicated by the generally high absolute PGE concentrations and mantle-like melt-depleted PGE patterns. The observed PGE signatures are consistent with the low bulk Al2O3 contents (mostly lower than 2.5%) of the peridotites, as well as the compositions of the silicate and oxide minerals. Based on PGE patterns and Os model ages, the peridotites from both localities can be categorized into three age groups: Archean (3.0-2.6 Ga overall; 2.8-2.6 Ga for Pelly Bay and 3.0-2.7 Ga for Repulse Bay), Paleoproterozoic (2.1-1.7 Ga), and "Recent" (<1 Ga, with model ages similar to the ca. 546 Ma kimberlite eruption age). The Archean group provides the first direct evidence of depleted Archean lithospheric mantle forming coevally with the overlying Archean crustal basement, indicating cratonization of the Rae during the Archean. The subtle difference in Os model ages between Pelly Bay and Repulse Bay coincides with the age difference between crustal basement rocks beneath these two areas, supporting the suggestion that the Rae craton was assembled by collision of separate two Archean blocks at 2.7-2.6 Ga. The Paleoproterozoic peridotites are interpreted to represent newly formed lithospheric mantle, most likely associated with regional-scale underplating during the 1.77-1.70 Ga Kivalliq-Nueltin event via removal of the lower portion of Archean lithospheric mantle followed by replacement with juvenile Paleoproterozoic lithospheric mantle. The existence of multiple age clusters in the lithosphere at each locality is consistent with the observation of present-day seismic lithospheric discontinuities (0540 and 0545) that indicate two or more layers of fossil lithospheric mantle fabric beneath this region. Our data define a shallow mantle lithosphere layer dominated by Archean depletion ages underlain by a layer of mixed Archean and Paleoproterozoic ages. This lithospheric mantle structure is probably a response to complex tectonic displacement of portions of the lithospheric mantle during Paleoproterozoic orogeny/underplating. The best equilibrated Archean and Paleoproterozoic peridotites at both Pelly Bay and Repulse Bay define a typical cratonic geotherm at the time of kimberlite eruption, with a ?200 km thick lithospheric root extending well into the diamond stability field, in keeping with the diamondiferous nature of the kimberlites. Such thick lithosphere remains in place to the present day as suggested by seismic and magnetotelluric studies (0540, 0545 and 0550). The metasomatically disturbed peridotites in the Rae lithospheric mantle, yielding model ages indistinguishable from kimberlite eruption, may represent parts of the Rae craton mantle root that show anomalous magnetotelluric signatures.
DS201601-0040
2015
Pearson, D.G.Riches, A.J.V., Ickert, R.B., Pearson, D.G., Stern, R.A., Jackson, S.E., Ishikawa, A.In situ oxygen isotope, major-, and trace element constraints on the metasomatic modification and crustal origin of a Diamondiferous eclogite from Roberts Victor, Kaapvaal Craton.Geochimica et Cosmochimica Acta, in press available, 45p.Africa, South AfricaDeposit - Roberts Victor
DS201602-0190
2016
Pearson, D.G.Aulbach, S., Mungall, J.E., Pearson, D.G.Distribution and processing of highly siderophile elements in cratonic mantle lithosphere.Reviews in Mineralogy and Geochemistry, Vol. 81, pp. 239-304.MantleMineralogy

Abstract: Cratonic lithospheric mantle is composed of predominantly refractory materials that formed at higher mantle potential temperatures (TP) than recorded in non-cratonic peridotites. It also shows stronger depletion and fractionation of Pd and Pt from Ru, Os and Ir than oceanic, supra-subduction zone or off-cratonic lithospheric mantle, as well as some of the lowest Se and Te contents. The varied response of the highly siderophile elements (HSE: Os, Ir, Ru, Rh, Pt, Pd, Re, Au), and their embedded radioactive decay systems, to changes in oxygen fugacity (fO2), sulfur fugacity (fS2) and pressure (P)-in particular through the impact of these parameters on the stability of the main HSE-bearing sulfide and alloy phases makes them potentially powerful tracers of their melting environment. Therefore, investigation of the HSE systematics of cratonic mantle peridotites, in combination with information from Re–Os isotopes on time-integrated enrichment or depletion, can help us to understand processes leading to mantle differentiation and continental lithosphere formation in the Archean, which are controversial subjects despite decades of research. The longevity of the cratonic lithosphere implies that there was ample opportunity for secondary overprint, obscuring our view of earlier processes. For example, destabilization of platinum-group element (PGE: Os, Ir, Ru, Rh, Pt, Pd) alloy leading to depletions in the compatible PGE, and perhaps Pt, in some cratonic mantle samples may occur in an oxidizing mantle wedge or through interaction with oxidizing small-volume, volatile-rich melts that typically invade cratonic roots. Such melts may eventually deposit S, Pd, Pt and Re and also capture remaining PGE alloys, consistent with the anomalous S-rich character of many kimberlite-borne xenoliths. Their basalt-borne counterparts show additional late effects of subaerial degassing that can deplete volatile elements (S, Re, Os). Basaltic melts can also scavenge PGE alloys at depth, while still sulfide-undersaturated. Such melts, may, on ascent, add sulfides when they become sulfur-saturated and, during the process, refertilize the mantle and modify major-element and modal compositions. The investigation of minor lithologies in the cratonic lithosphere, such as eclogites and pyroxenites, which are expressions of tectonothermal events ranging from subduction to melt infiltration, can enhance our understanding of the effects of these processes on HSE redistribution. Thus, three major topics will be discussed, using HSE systematics in cratonic mantle samples: (1) How did the HSE behave during the (in part) extreme degrees of partial melt extraction experienced by cratonic lithospheric mantle; (2) What were the effects of the secular metasomatic overprint of the cratonic mantle; (3) What was the composition of the Archean convecting mantle, for which cratonic mantle samples may afford better insight than modern samples, provided, of course, that we have an accurate grasp of how HSE are redistributed during partial melting and metasomatism. Models based on experiments done under controlled pressure (P), temperature (T), fO2 and fS2 conditions can help place the data in context and to distinguish between melt- and metasomatism-related processes. Disentangling the various primary and secondary effects is only possible when HSE are studied in combination with lithophile elements, with due attention to petrography and mineralogy. This adds many layers of complexity, but ultimately allows a more complete understanding of the variegated processes that have shaped the cratonic lithosphere through time. In this review, we commence by discussing the peculiarities and complexities of continental lithospheric mantle origin, evolution and current state. We then introduce the database used in this contribution, followed by a brief review of the mineral hosts of HSE in peridotite and of the diverse approaches to isolate the HSE for measurement. We examine the behavior of the HSE during the formation of cratonic lithospheric mantle under non-uniformitarian conditions, where the application of the Re–Os isotope system has afforded particularly useful information on the timing of initial melt depletion and the stabilization of cratonic roots. We then turn to the effects of mantle metasomatism, both during intra-plate and craton-margin processes (see also Gannoun et al. 2016, this volume), on HSE systematics in cratonic mantle. We also discuss the data in the context of melt extraction modelling that shed light on the primary versus secondary HSE signatures in cratonic mantle rocks. Finally, we evaluate the possibility that the HSE in cratonic mantle retain a memory of core formation and subsequent accretionary processes.
DS201602-0219
2016
Pearson, D.G.Liu, J., Riches, A.J.V., Pearson, D.G., Luo, Y., Kienlen, B., Kjarsgaard, B.A., Stachel, T., Armstrong, J.P.Age and evolution of the deep continental root beneath the central Rae craton, northern Canada.Precambrian Research, Vol. 272, pp. 168-184.Canada, Northwest TerritoriesGeochronology

Abstract: Canada is host to at least six separate cratons that comprise a significant proportion of its crustal extent. Of these cratons, we possess knowledge of the cratonic lithospheric roots beneath only the Slave craton and, to a lesser extent, the Superior craton, despite the discovery of many new diamond-bearing kimberlites in Canada's North. Here we present the first age, composition and geothermal information for kimberlite-borne peridotite xenoliths from two localities within the central Rae craton: Pelly Bay and Repulse Bay. Our aim is to investigate the nature and evolution of the deep lithosphere in these regions and to examine how events recorded in the mantle may or may not correlate with the complex history of crustal evolution across the craton. Peridotite xenoliths are commonly altered by secondary processes including serpentinization, silicification and carbonation, which have variably affected the major element compositions. These secondary processes, as well as mantle metasomatism recorded in pristine silicate minerals, however, did not significantly modify the relative compositions of platinum-group elements (PGE) and Os isotope ratios in the majority of our samples from Pelly Bay and Repulse Bay, as indicated by the generally high absolute PGE concentrations and mantle-like melt-depleted PGE patterns. The observed PGE signatures are consistent with the low bulk Al2O3 contents (mostly lower than 2.5%) of the peridotites, as well as the compositions of the silicate and oxide minerals. Based on PGE patterns and Os model ages, the peridotites from both localities can be categorized into three age groups: Archean (3.0-2.6 Ga overall; 2.8-2.6 Ga for Pelly Bay and 3.0-2.7 Ga for Repulse Bay), Paleoproterozoic (2.1-1.7 Ga), and “Recent” (<1 Ga, with model ages similar to the ca. 546 Ma kimberlite eruption age). The Archean group provides the first direct evidence of depleted Archean lithospheric mantle forming coevally with the overlying Archean crustal basement, indicating cratonization of the Rae during the Archean. The subtle difference in Os model ages between Pelly Bay and Repulse Bay coincides with the age difference between crustal basement rocks beneath these two areas, supporting the suggestion that the Rae craton was assembled by collision of separate two Archean blocks at 2.7-2.6 Ga. The Paleoproterozoic peridotites are interpreted to represent newly formed lithospheric mantle, most likely associated with regional-scale underplating during the 1.77-1.70 Ga Kivalliq-Nueltin event via removal of the lower portion of Archean lithospheric mantle followed by replacement with juvenile Paleoproterozoic lithospheric mantle. The existence of multiple age clusters in the lithosphere at each locality is consistent with the observation of present-day seismic lithospheric discontinuities (0540 and 0545) that indicate two or more layers of fossil lithospheric mantle fabric beneath this region. Our data define a shallow mantle lithosphere layer dominated by Archean depletion ages underlain by a layer of mixed Archean and Paleoproterozoic ages. This lithospheric mantle structure is probably a response to complex tectonic displacement of portions of the lithospheric mantle during Paleoproterozoic orogeny/underplating. The best equilibrated Archean and Paleoproterozoic peridotites at both Pelly Bay and Repulse Bay define a typical cratonic geotherm at the time of kimberlite eruption, with a ?200 km thick lithospheric root extending well into the diamond stability field, in keeping with the diamondiferous nature of the kimberlites. Such thick lithosphere remains in place to the present day as suggested by seismic and magnetotelluric studies (0540, 0545 and 0550). The metasomatically disturbed peridotites in the Rae lithospheric mantle, yielding model ages indistinguishable from kimberlite eruption, may represent parts of the Rae craton mantle root that show anomalous magnetotelluric signatures.
DS201603-0417
2016
Pearson, D.G.Riches, A.J.V., Ickert, R.B., Pearson, D.G., Stern, R.A., Jackson, S.E., Ishikawa, A., Kjarsgaard, B.A., Gurney, J.J.In situ oxygen-isotope, major, and trace element constraints on the metasomatic modification and crust origin of a Diamondiferous eclogite from Roberts Victor, Kaapvaal craton.Geochimica et Cosmochimica Acta, Vol. 174, pp. 345-359.Africa, South AfricaDeposit - Roberts Victor
DS201603-0420
2016
Pearson, D.G.Shu, Q., Brey, G.P., Hoefer, H.E., Zhao, Z., Pearson, D.G.Kyanite/corundum eclogites from the Kaapvaal craton: subducted troctolites and layered gabbros from the Mid- to Early Archean.Contributions to Mineralogy and Petrology, Vol. 171, 11, 24p.Africa, South AfricaDeposit - Bellsbank

Abstract: An oceanic crustal origin is the commonly accepted paradigm for mantle-derived eclogites. However, the significance of the aluminous members of the eclogite suite, containing kyanite and corundum, has long been underrated and their role neglected in genetic models of cratonic evolution. Here, we present a geochemical and petrological study of a suite of kyanite- and corundum-bearing eclogites from the Bellsbank kimberlite, S. Africa, which originate from depths between 150 and 200 km. Although clearly of high-pressure provenance, these rocks had a low-pressure cumulative origin with plagioclase and olivine as major cumulate phases. This is shown by the very pronounced positive Eu anomalies, low REE abundances, and ? 18O values lower than the Earth’s mantle. Many chemical features are identical to modern-day troctolitic cumulates including a light REE depletion akin to MORB, but there are also distinguishing features in that the eclogites are richer in Na, Fe, and Ni. Two of the eclogites have a minimum age of ~3.2 Ga, defined by the extremely unradiogenic 87Sr/86Sr (0.7007) in clinopyroxene. Phase equilibria indicate that the parent melts were formed by partial melting below an Archean volcanic center that generated (alkali-)picritic to high-alumina tholeiitic melts from a mantle whose oxygen fugacity was lower than today. Fractional crystallization produced troctolites with immiscible sulfide melt droplets within the mafic crust. Instability of the mafic crust led to deep subduction and re-equilibration at 4 6 GPa. Phase relationships plus the presence of a sample with appreciable modal corundum but no Eu anomaly suggest that kyanite- and corundum-bearing eclogites may also originate as plagioclase-free, higher pressure cumulates of highly aluminous clinopyroxene, spinel, and olivine. This is consistent with the crystallizing phase assemblage from an olivine tholeiitic to picritic magma deeper in the Archean oceanic crust or uppermost mantle. We postulate that the magmatic and subduction processes driving modern plate tectonics already existed in the Meso- to Early Archean.
DS201604-0596
2016
Pearson, D.G.Bussweiler, Y., Pearson, D.G., Luth, R.W., Kjarsgaard, B.A., Stachel, T.The evolution of calcite-bearing kimberlite by rock-melt reaction during ascent - evidence from polymineralic inclusions within Cr- diopside and Cr-pyrope megacrysts from Lac de Gras kimberlites, Northwest Territories, Canada.GAC MAC Meeting Special Session SS11: Cratons, kimberlites and diamonds., abstract 1/4p.Canada, Northwest TerritoriesDeposit - Lac de Gras
DS201604-0616
2016
Pearson, D.G.Krebs, M.Y., Pearson, D.G., Stachel, T., Stern, R.A., Nowicki, T., Cairns, S.Using microdiamonds in kimberlite diamond grade prediction: a case study of the variability in diamond population characteristics across the size range 0.2 to 3.4 mm in Misery kimberlite, Ekati mine, NWT, Canada.Economic Geology, Vol. 111, 2, pp. 503-525.Canada, Northwest TerritoriesMicrodiamonds - Misery

Abstract: First predictions of the macrodiamond grade of newly discovered kimberlites are commonly obtained using size frequency distributions of microdiamonds. The success of this approach suggests a common origin of microdiamonds and macrodiamonds, an implication not yet conclusively established or disproved. In contrast to previous comparative studies on microdiamonds and macrodiamonds from single deposits, here all diamonds analyzed originate from the same microdiamond samples (558 diamonds, ranging from 0.212 to 3.35 mm). The diamonds were analyzed for their carbon isotope compositions and nitrogen characteristics, and, based on this dataset, statistical comparisons were conducted across the size range to assess cogenesis. As a whole, the Misery diamond suite shows high nitrogen contents (median = 850 at. ppm), a bimodal distribution in time-averaged mantle residence temperatures (two distinct subpopulations in mantle residence temperatures: ?1,125° and ?1,175°C), a high degree of platelet degradation, and ?13C compositions that are isotopically slightly heavier (median = ?4.4‰) than the global median. Statistical comparisons of the various size classes indicate the presence of subtly different subpopulations at Misery; however, the nature and magnitude of these geochemical differences are very small in the context of the global diamond database and are viewed as petrogenetically insignificant. The general geochemical similarity of diamonds from different size fractions at Misery reinforces the use of size-frequency analysis to predict diamond grade in kimberlite diamond deposits.
DS201604-0622
2016
Pearson, D.G.Poitras, S., Pearson, D.G., Stachel, T., Cairns, S., Day, S.A geochemical study of diamond indicator minerals from the NWT Interior Platform.GAC MAC Meeting Special Session SS11: Cratons, kimberlites and diamonds., abstract 1/4p.Canada, Northwest TerritoriesDiamond indicators

Abstract: The Central Mackenzie Valley (CMV) area of the Northwest Territories (NWT) comprises a Phanerozoic sedimentary basin that lies between the western margin of the Slave craton and the Cordillera. Although the region is considerably outside the bounds of the exposed Slave craton, both LITHOPROBE and more recent regional-scale surface wave studies (e.g., Priestley and McKenzie, 2006) indicate the likely presence of lithospheric mantle extending into the diamond stability field. Recent work conducted by Olivut Resources Ltd. led to the discovery of 29 kimberlites in the CMV. However, the indicator mineral chemistry of discovered kimberlites does not appear to be a good match (www.olivut.ca) with those during regional till and stream sediment sampling by the Geologic Survey of Canada (GSC) and Northwest Territories Geologic Survey (NTGS) in August 2003 and July 2005. We present new geochemical data on the regional indicator minerals with the aim of obtaining geotherm and depth of mantle sampling constraints on those indicator minerals discovered to date. A statistical evaluation of the data will compare the similarities to indicator mineral chemistry with parts of the Slave craton to evaluate whether the CMV indicators may ultimately be derived from that region. In total 3600 kimberlite indicator mineral grains were picked from the 0.25-2.0 mm size fractions. Peridotitic garnet grains dominate (46%), followed by magnesium ilmenite (26%), with decreasing individual proportions >15% of chromite, low-chrome diopside, olivine, chrome-diopside and eclogitic garnet. A sub-sample of these grains (3143) were analysed by EPMA. Garnet grains classify (after Grütter et al., 2004) as 1015 (62.1%) G9, 270 (16.5%) G11, 113 (6.9%) G10, 103 (6.3%) G12, 57 (3.5%) G1, 46 (2.8%) G10D, and the remaining 31 (1.9%) as G0, G3, G3D, G4, and G5. A sub-set of garnet grains (~700) were selected for LA-ICP-MS trace element analysis. Of the grains selected 74% G9, 14% G10 (and G10D), and 8% G11, with only 4% G12 and G0 (Grütter et al., 2004). Nickel concentrations from these grains range from 2.6-168.2 ppm, with the majority (>80%) between 20-100 ppm, yielding TNi (Canil, 1999) values ranging from 643-1348°C, with the majority between ~1000-1200°C. Using a central Slave craton geothermal gradient (Hasterok and Chapman, 2011), equilibration pressures for these garnet grains range from 20-80 kbars with the majority between 40-60 kbars (120-185 km). Preliminary analysis has 581 (81%) of the erupted peridotitic mantle garnet grains plotting within the diamond stability field (Kennedy and Kennedy, 1976). Of the 128 clinopyroxene grains analysed, only a few represent garnet peridotite (lherzolite) facies KIM clinopyroxene grains following compositional screening. Thermobarometry of these grains (Nimis and Taylor, 2000), assuming they were all derived from the same lithospheric section, yields P-T arrays identical to the central Slave geotherm that was 220 km thick at the time of eruption. These results are encouraging for diamond exploration. We thank Overburden Drilling Management Ltd. for grain picking and recovery of the small diamond, SGS Lakefield Research for mounting grains, and the GSC for probing of the grains.
DS201604-0628
2016
Pearson, D.G.Shirey, S.B., Pearson, D.G.Diamond ages: what do they mean?GAC MAC Meeting Special Session SS11: Cratons, kimberlites and diamonds., Keynote abstractTechnologyDiamond ages
DS201604-0631
2016
Pearson, D.G.Stachel, T., Stern, R.A., Luth, R.W., Pearson, D.G., Harris, J.W., DCO - Diamond ConsortiumModes of diamond precipitation through time.GAC MAC Meeting Special Session SS11: Cratons, kimberlites and diamonds., abstract 1/4p.TechnologyDiamond genesis
DS201604-0638
2016
Pearson, D.G.Weiss, Y., Pearson, D.G.Subduction-related Mesozoic metasomatism and diamond formation in the continental lithosphere under the Northwest Territories, Canada.GAC MAC Meeting Special Session SS11: Cratons, kimberlites and diamonds., abstract 1/4p.Canada, Northwest TerritoriesSubduction
DS201607-1288
2016
Pearson, D.G.Bussweiler, Y., Stone, R.S., Pearson, D.G., Luth, R.W., Stachel, T., Kjarsgaard, B.A., Menzies, A.The evolution of calcite bearing kimberlites by melt rock reaction: evidence from polymineralic inclusions within clinopyroxene and garnet megacrysts from Lac de Gras kimberlites, Canada.Contributions to Mineralogy and Petrology, Vol. 171, 7, 25p.Canada, Northwest TerritoriesDeposit - Lac de Gras arena

Abstract: Megacrystic (>1 cm) clinopyroxene (Cr-diopside) and garnet (Cr-pyrope) xenocrysts within kimberlites from Lac de Gras (Northwest Territories, Canada) contain fully crystallized melt inclusions. These ‘polymineralic inclusions’ have previously been interpreted to form by necking down of melts at mantle depths. We present a detailed petrographical and geochemical investigation of polymineralic inclusions and their host crystals to better understand how they form and what they reveal about the evolution of kimberlite melt. Genetically, the megacrysts are mantle xenocrysts with peridotitic chemical signatures indicating an origin within the lithospheric mantle (for the Cr-diopsides studied here ~4.6 GPa, 1015 °C). Textural evidence for disequilibrium between the host crystals and their polymineralic inclusions (spongy rims in Cr-diopside, kelyphite in Cr-pyrope) is consistent with measured Sr isotopic disequilibrium. The preservation of disequilibrium establishes a temporal link to kimberlite eruption. In Cr-diopsides, polymineralic inclusions contain phlogopite, olivine, chromite, serpentine, and calcite. Abundant fluid inclusion trails surround the inclusions. In Cr-pyropes, the inclusions additionally contain Al-spinel, clinopyroxene, and dolomite. The major and trace element compositions of the inclusion phases are generally consistent with the early stages of kimberlite differentiation trends. Extensive chemical exchange between the host phases and the inclusions is indicated by enrichment of the inclusions in major components of the host crystals, such as Cr2O3 and Al2O3. This chemical evidence, along with phase equilibria constraints, supports the proposal that the inclusions within Cr-diopside record the decarbonation reaction: dolomitic melt + diopside ? forsterite + calcite + CO2, yielding the observed inclusion mineralogy and producing associated (CO2-rich) fluid inclusions. Our study of polymineralic inclusions in megacrysts provides clear mineralogical and chemical evidence for an origin of kimberlite that involves the reaction of high-pressure dolomitic melt with diopside-bearing mantle assemblages producing a lower-pressure melt that crystallizes a calcite-dominated assemblage in the crust.
DS201608-1397
2016
Pearson, D.G.Bussweiler, Y., Stone, R.S., Pearson, D.G., Luth, R.W., Stachel, T., Kjarsgaard, B.A., Menzies, A.The evolution of calcite bearing kimberlites by melt rock reaction: evidence from polymineralic inclusions within clinopyroxene and garnet megacrysts from Lac de Gras kimberlites, Canada.Contributions to Mineralogy and Petrology, in press available 25p.Canada, Northwest TerritoriesDeposit - Lac de Gras

Abstract: Megacrystic (>1 cm) clinopyroxene (Cr-diopside) and garnet (Cr-pyrope) xenocrysts within kimberlites from Lac de Gras (Northwest Territories, Canada) contain fully crystallized melt inclusions. These ‘polymineralic inclusions’ have previously been interpreted to form by necking down of melts at mantle depths. We present a detailed petrographical and geochemical investigation of polymineralic inclusions and their host crystals to better understand how they form and what they reveal about the evolution of kimberlite melt. Genetically, the megacrysts are mantle xenocrysts with peridotitic chemical signatures indicating an origin within the lithospheric mantle (for the Cr-diopsides studied here ~4.6 GPa, 1015 °C). Textural evidence for disequilibrium between the host crystals and their polymineralic inclusions (spongy rims in Cr-diopside, kelyphite in Cr-pyrope) is consistent with measured Sr isotopic disequilibrium. The preservation of disequilibrium establishes a temporal link to kimberlite eruption. In Cr-diopsides, polymineralic inclusions contain phlogopite, olivine, chromite, serpentine, and calcite. Abundant fluid inclusion trails surround the inclusions. In Cr-pyropes, the inclusions additionally contain Al-spinel, clinopyroxene, and dolomite. The major and trace element compositions of the inclusion phases are generally consistent with the early stages of kimberlite differentiation trends. Extensive chemical exchange between the host phases and the inclusions is indicated by enrichment of the inclusions in major components of the host crystals, such as Cr2O3 and Al2O3. This chemical evidence, along with phase equilibria constraints, supports the proposal that the inclusions within Cr-diopside record the decarbonation reaction: dolomitic melt + diopside ? forsterite + calcite + CO2, yielding the observed inclusion mineralogy and producing associated (CO2-rich) fluid inclusions. Our study of polymineralic inclusions in megacrysts provides clear mineralogical and chemical evidence for an origin of kimberlite that involves the reaction of high-pressure dolomitic melt with diopside-bearing mantle assemblages producing a lower-pressure melt that crystallizes a calcite-dominated assemblage in the crust.
DS201608-1430
2016
Pearson, D.G.Palot, M., Jacobsen, S.D., Townsend, J.P., Nestols, F., Marquardt, K., Harris, J.W., Stachel, T., McCammon, C.A., Pearson, D.G.Evidence for H2O bearing fluids in the lower mantle from diamond inclusion.Lithos, in press available 27p.South America, BrazilSao Luis

Abstract: In this study, we report the first direct evidence for water-bearing fluids in the uppermost lower mantle from natural ferropericlase crystal contained within a diamond from São Luíz, Brazil. The ferropericlase exhibits exsolution of magnesioferrite, which places the origin of this assemblage in the uppermost part of the lower mantle. The presence of brucite-Mg(OH)2 precipitates in the ferropericlase crystal reflects the later-stage quenching of H2O-bearing fluid likely in the transition zone, which has been trapped during the inclusion process in the lower mantle. Dehydration melting may be one of the key processes involved in transporting water across the boundary between the upper and lower mantle.
DS201608-1432
2016
Pearson, D.G.Pearson, D.G., Weiss, Y.Diamond forming fluids - the importance of being salty.GSA Annual Meeting, Abstract, 1p.Canada, Northwest TerritoriesDeposit - Ekati, Diavik

Abstract: Fluids are now thought to be the growth medium for most diamonds sampled from the base of the lithosphere. Fluids trapped in fast-growing, fluid-rich diamonds provide the only direct view of this growth medium and provide valuable information on the geochemistry of deep mantle fluids in general. The most common fluids within fluid-rich diamonds are those belonging to the low- and high-Mg carbonatite affinity as well as more Si-rich variants. A sub-class of fluids that are very rich in alkalis and Cl, known as “saline” fluids, have been found but are generally scarce. At both Ekati and Diavik saline fluids appear much more common and provide a unique insight into their origin. We describe a novel sampling method that allows the analysis of the trace element and radiogenic isotope composition of diamonds (both gem and fluid-rich). Using these methods we analyzed 11 diamonds from the Fox kimberlite in the Ekati kimberlite cluster. The diamonds containing saline fluids are solely associated with peridotite on the basis of their micro-mineral inclusions. Silicic fluid compositions are related exclusively to eclogitic inclusions. Striking differences between the two fluid compositions are the positive Eu and Sr anomalies within saline fluids versus no anomalies in the silicic fluids. These characteristics are identical to previously studied fluids in fibrous diamonds from neighbouring kimberlites in Ekati and Diavik, which also contains diamonds carrying high- and low-Mg carbonatitic fluids. Combining the data, we show a clear chemical evolutionary trend, identifying for the first time saline fluids as parental to silicic and carbonatitic deep mantle melts, via fluid-rock interaction in the Slave CLM. Moreover, the trace-element and Sr isotopic fingerprints of subducting slabs and the timing of host diamond formation suggest that a subducting plate under western North America is the source of the saline fluids, which controlled metasomatism in the Slave lithosphere prior to Mesozoic kimberlite eruption. Saline fluids can be documented as a metasomatic product interacting with the lithosphere above shallow-subducting slabs such as the Farallon slab. As such they appear to be key players in the enrichment of the base of the lithosphere and the formation of diamonds.
DS201610-1896
2016
Pearson, D.G.Pearson, D.G., Weiss, Y.Diamond-forming fluids - the importance of being salty. Ekati and DiavikGSA Annual Meeting, 1/2p. abstractCanada, Northwest TerritoriesSaline fluids

Abstract: Fluids are now thought to be the growth medium for most diamonds sampled from the base of the lithosphere. Fluids trapped in fast-growing, fluid-rich diamonds provide the only direct view of this growth medium and provide valuable information on the geochemistry of deep mantle fluids in general. The most common fluids within fluid-rich diamonds are those belonging to the low- and high-Mg carbonatite affinity as well as more Si-rich variants. A sub-class of fluids that are very rich in alkalis and Cl, known as “saline” fluids, have been found but are generally scarce. At both Ekati and Diavik saline fluids appear much more common and provide a unique insight into their origin. We describe a novel sampling method that allows the analysis of the trace element and radiogenic isotope composition of diamonds (both gem and fluid-rich). Using these methods we analyzed 11 diamonds from the Fox kimberlite in the Ekati kimberlite cluster. The diamonds containing saline fluids are solely associated with peridotite on the basis of their micro-mineral inclusions. Silicic fluid compositions are related exclusively to eclogitic inclusions. Striking differences between the two fluid compositions are the positive Eu and Sr anomalies within saline fluids versus no anomalies in the silicic fluids. These characteristics are identical to previously studied fluids in fibrous diamonds from neighbouring kimberlites in Ekati and Diavik, which also contains diamonds carrying high- and low-Mg carbonatitic fluids. Combining the data, we show a clear chemical evolutionary trend, identifying for the first time saline fluids as parental to silicic and carbonatitic deep mantle melts, via fluid-rock interaction in the Slave CLM. Moreover, the trace-element and Sr isotopic fingerprints of subducting slabs and the timing of host diamond formation suggest that a subducting plate under western North America is the source of the saline fluids, which controlled metasomatism in the Slave lithosphere prior to Mesozoic kimberlite eruption. Saline fluids can be documented as a metasomatic product interacting with the lithosphere above shallow-subducting slabs such as the Farallon slab. As such they appear to be key players in the enrichment of the base of the lithosphere and the formation of diamonds.
DS201610-1903
2016
Pearson, D.G.Reimink, J.R., Davies, J.H.F.L., Chacko, T., Stern, R.A., Heaman, L.M., Sarkar, C., Schaltegger, U., Creaser, R.A., Pearson, D.G.No evidence for Hadean continental crust within Earth's oldest evolved rock unit. (Acasta Gneiss Complex)Nature Geoscience, Vol. 9, pp. 777-780.CanadaHadean crust

Abstract: Due to the acute scarcity of very ancient rocks, the composition of Earth’s embryonic crust during the Hadean eon (>4.0 billion years ago) is a critical unknown in our search to understand how the earliest continents evolved. Whether the Hadean Earth was dominated by mafic-composition crust, similar to today’s oceanic crust1, 2, 3, 4, or included significant amounts of continental crust5, 6, 7, 8 remains an unsolved question that carries major implications for the earliest atmosphere, the origin of life, and the geochemical evolution of the crust-mantle system. Here we present new U-Pb and Hf isotope data on zircons from the only precisely dated Hadean rock unit on Earth—a 4,019.6 ± 1.8?Myr tonalitic gneiss unit in the Acasta Gneiss Complex, Canada. Combined zircon and whole-rock geochemical data from this ancient unit shows no indication of derivation from, or interaction with, older Hadean continental crust. Instead, the data provide the first direct evidence that the oldest known evolved crust on Earth was generated from an older ultramafic or mafic reservoir that probably surfaced the early Earth.
DS201610-1904
2016
Pearson, D.G.Scott, J.M., Liu, J., Pearson, D.G., Waight, T.E.Mantle depletion and metasomatism recorded in orthopyroxene in highly depleted peridotites.Chemical Geology, Vol. 441, pp. 280-291.MantleMetasomatism

Abstract: Although trace element concentrations in clinopyroxene serve as a useful tool for assessing the depletion and enrichment history of mantle peridotites, this is not applicable for peridotites in which the clinopyroxene component has been consumed (~ 25% partial melting). Orthopyroxene persists in mantle residues until ~ 40% melting and it is therefore this mineral that offers petrological insights into the evolution of refractory peridotites. Major and trace element concentrations in orthopyroxene ± clinopyroxene from two spinel facies harzburgitic xenolith suites from New Zealand are examined. Samples from Cape L'Evique (CLEV) on Chatham Island contain traces of clinopyroxene (< 2 modal %) but a suite from Lake Moana (MOA) in the South Island is devoid of this mineral. When compared with modelled orthopyroxene trace element budgets, which are constructed from a review of published source modes, melting modes and element/melt partition co-efficients, the measured orthopyroxene rare earth element data in both suites generally indicate minimums of 25-30% partial melting. These results are consistent with co-existing elevated Mg# in olivine (mostly 91.4 to 93.0) and orthopyroxene (mostly 91.3 to 93.6), high spinel Cr# (commonly > 45) and low orthopyroxene Al2O3 (generally < 3.1 wt%). However, comparison of modelled and measured orthopyroxene compositions shows that all samples, even the most refractory, have undergone metasomatism by small volume light rare earth element-bearing agents. Measured orthopyroxene Ti concentrations show that the metasomatic agent that affected the CLEV suite carried Ti, but that the MOA suite metasomatiser was Ti-poor. Orthopyroxene trace elements in the inspected rocks are therefore partly decoupled from the major element abundances, with the results demonstrating that even highly refractory peridotites can record evidence for mantle metasomatism.
DS201612-2329
2016
Pearson, D.G.Reimink, J.R., Davies, J.H.F.L., Chacko, T., Stern, R.A., Heaman, L.M., Sarkar, C., Schaltegger, U., Creaser, R.A., Pearson, D.G.No evidence for Hadean continental crust within Earth's oldest evolved rock unit.Nature Geoscience, Vol. 9, pp. 777-780.CanadaAcasta Gneiss

Abstract: Due to the acute scarcity of very ancient rocks, the composition of Earth’s embryonic crust during the Hadean eon (>4.0 billion years ago) is a critical unknown in our search to understand how the earliest continents evolved. Whether the Hadean Earth was dominated by mafic-composition crust, similar to today’s oceanic crust1, 2, 3, 4, or included significant amounts of continental crust5, 6, 7, 8 remains an unsolved question that carries major implications for the earliest atmosphere, the origin of life, and the geochemical evolution of the crust-mantle system. Here we present new U-Pb and Hf isotope data on zircons from the only precisely dated Hadean rock unit on Earth—a 4,019.6 ± 1.8?Myr tonalitic gneiss unit in the Acasta Gneiss Complex, Canada. Combined zircon and whole-rock geochemical data from this ancient unit shows no indication of derivation from, or interaction with, older Hadean continental crust. Instead, the data provide the first direct evidence that the oldest known evolved crust on Earth was generated from an older ultramafic or mafic reservoir that probably surfaced the early Earth.
DS201701-0033
2017
Pearson, D.G.Snyder, D.B., Humphreys, E., Pearson, D.G.Construction and destruction of some North American cratons. Rae, Slave, WyomingTectonophysics, Vol. 694, pp. 464-486.United States, CanadaMetasomatism

Abstract: Construction histories of Archean cratons remain poorly understood; their destruction is even less clear because of its rarity, but metasomatic weakening is an essential precursor. By assembling geophysical and geochemical data in 3-D lithosphere models, a clearer understanding of the geometry of major structures within the Rae, Slave and Wyoming cratons of central North America is now possible. Little evidence exists of subducted slab-like geometries similar to modern oceanic lithosphere in these construction histories. Underthrusting and wedging of proto-continental lithosphere is inferred from multiple dipping discontinuities, emphasizing the role of lateral accretion. Archean continental building blocks may resemble the modern lithosphere of oceanic plateau, but they better match the sort of refractory crust expected to have formed at Archean ocean spreading centres. Radiometric dating of mantle xenoliths provides estimates of rock types and ages at depth beneath sparse kimberlite occurrences, and these ages can be correlated to surface rocks. The 3.6-2.6 Ga Rae, Slave and Wyoming cratons stabilized during a granitic bloom at 2.61-2.55 Ga. This stabilization probably represents the final differentiation of early crust into a relatively homogeneous, uniformly thin (35-42 km), tonalite-trondhjemite-granodiorite crust with pyroxenite layers near the Moho atop depleted lithospheric mantle. Peak thermo-tectonic events at 1.86-1.7 Ga broadly metasomatized, mineralized and recrystallized mantle and lower crustal rocks, apparently making mantle peridotite more ‘fertile’ and more conductive by introducing or concentrating sulfides or graphite at 80-120 km depths. This metasomatism may have also weakened the lithosphere or made it more susceptible to tectonic or chemical erosion. Late Cretaceous flattening of Farallon lithosphere that included the Shatsky Rise conjugate appears to have weakened, eroded and displaced the base of the Wyoming craton below 140-160 km. This process replaced the old re-fertilized continental mantle with relatively young depleted oceanic mantle.
DS201702-0251
2017
Pearson, D.G.Wang, H., van Hunen, J., Pearson, D.G.Making Archean cratonic roots by lateral compression: a two stage thickening and stabilization model.Tectonophysics, in press available, 10p.MantleCraton, tectonics

Abstract: Archean tectonics was capable of producing virtually indestructible cratonic mantle lithosphere, but the dominant mechanism of this process remains a topic of considerable discussion. Recent geophysical and petrological studies have refuelled the debate by suggesting that thickening and associated vertical movement of the cratonic mantle lithosphere after its formation are essential ingredients of the cratonization process. Here we present a geodynamical study that focuses on how the thick stable cratonic lithospheric roots can be made in a thermally evolving mantle. Our numerical experiments explore the viability of a cratonization process in which depleted mantle lithosphere grows via lateral compression into a > 200-km thick, stable cratonic root and on what timescales this may happen. Successful scenarios for craton formation, within the bounds of our models, are found to be composed of two stages: an initial phase of tectonic shortening and a later phase of gravitational self-thickening. The initial tectonic shortening of previously depleted mantle material is essential to initiate the cratonization process, while the subsequent gravitational self-thickening contributes to a second thickening phase that is comparable in magnitude to the initial tectonic phase. Our results show that a combination of intrinsic compositional buoyancy of the cratonic root, rapid cooling of the root after shortening, and the long-term secular cooling of the mantle prevents a Rayleigh-Taylor type collapse, and will stabilize the thick cratonic root for future preservation. This two-stage thickening model provides a geodynamically viable cratonization scenario that is consistent with petrological and geophysical constraints.
DS201703-0436
2017
Pearson, D.G.Van Acken, D., Luguet, A., Pearson, D.G., Nowell, G.M., Fonseca, R.O.C., Nagel, T.J., Schulz, T.Mesoarchean melting and Neoarchean ro Paleoproterozoic metasomatism during the formation of the cratonic mantle keel beneath West Greenland.Geochimica et Cosmochimica Acta, Vol. 203, pp. 37-53.Europe, GreenlandCraton
DS201705-0833
2017
Pearson, D.G.Gress, M.U., Pearson, D.G., Timmerman, S., Chinn, I.L., Koornneef, J., Davies, G.R.Diamond growth beneath Letlhakane established by Re-Os and Sm-Nd systematics of individual eclogitic sulphide, garnet and clinopyroxene inclusions.European Geosciences Union General Assembly 2017, Vienna April 23-28, 1p. 5540 AbstractAfrica, BotswanaDeposit - Letlhakane

Abstract: The diamondiferous Letlhakane kimberlites are part of the Orapa kimberlite cluster (˜ 93.1 Ma) in north-eastern Botswana, located on the edge of the Zimbabwe Craton, close to the Proterozoic Magondi Mobile Belt. Here we report the first Re-Os ages of six individual eclogitic sulphide inclusions (3.0 to 35.7?g) from Letlhakane diamonds along with their rhenium, osmium, iridium and platinum concentrations, and carbon isotope, nitrogen content and N-aggregation data from the corresponding growth zones of the host diamonds. For the first time, Re-Os data will be compared to Sm-Nd ages of individual eclogitic silicate inclusions recovered from the same diamonds using a Triton Plus equipped with four 1013? amplifiers. The analysed inclusion set currently encompasses pairs of individual sulphides from two diamonds (LK040 sf4 & 5, LK113 sf1 & 2) and two sulphide inclusions from separate diamonds (LK048, LK362). Ongoing work will determine the Sm-Nd ages and element composition of multiple individual eclogitic garnets (LK113/LK362, n=4) and an eclogitic clinopyroxene (LK040) inclusion. TMA ages of the six sulphides range from 1.06 to 2.38 Ga (± 0.1 to 0.54 Ga) with Re and Os contents between 7 and 68 ppb and 0.03 and 0.3 ppb, respectively. The host diamond growth zones have low nitrogen abundances (21 to 43 ppm N) and high N-aggregation (53 to 90% IaB). Carbon isotope data suggests the involvement of crustal carbon (?13C between -19.3 to -22.7 ± 0.2 per mill) during diamond precipitation. Cathodoluminescence imaging of central plates from LK040 and LK113 displays homogenous internal structure with no distinct zonation. The two sulphide inclusions from LK040 define an 'isochron' of 0.92 ± 0.23 Ga (2SD) with initial 187Os/188Os = 1.31 ± 0.24. Sulphides from LK113 have clear imposed diamond morphology and indicate diamond formation at 0.93 ± 0.36 Ga (2SD) with initial 187Os/188Os = 0.69 ± 0.44. The variation in the initial 187Os/188Os does not justify including these inclusions (or any from other diamonds) on the same isochron and implies an extremely heterogeneous diamond crystallisation environment that incorporated recycled Os. C1-normalized osmium, iridium and platinum (PGE) compositions from the analysed sulphide inclusions display enrichment in Ir (3.4 to 33) and Pt (2.3 to 28.1) in comparison to eclogitic xenolith data from Orapa that are depleted relative to chondrite. The Re-Os isochrons determined in this study are within error of previously reported ages from the adjacent (˜40km) Orapa diamond mine (1.0 to 2.9 Ga) based on sulphide inclusions and a multi-point 990 ± 50 Ma (2SD) isochron for composite (n=730) silicate inclusions. Together with additional new Sm-Nd isochron age determinations from individual silicate inclusions from Letlhakane (2.3 ± 0.02 (n = 3); 1.0 ± 0.14 (n = 4) and 0.25 ± 0.04 Ga (n = 3), all 2SE) these data suggest a phase of Mesoproterozoic diamond formation as well as Neoarchean/Paleoproterozoic and Mesozoic diamond growth, in punctuated events spanning >2.0 Ga.
DS201705-0877
2017
Pearson, D.G.Sommer, H., Jacob, D.E., Stern, R.A., Petts, D., Mattey, D.P., Pearson, D.G.Fluid induced transition from banded kyanite to bimineralic eclogite and implications for the evolution of cratons.Geochimica et Cosmochimica Acta, in press available 55p.Africa, South AfricaDeposit - Roberts Victor

Abstract: Heterogeneous, modally banded kyanite-bearing and bimineralic eclogites from the lithospheric mantle, collected at the Roberts Victor Diamond mine (South Africa), show a reaction texture in which kyanite is consumed. Geothermobarometric calculations using measured mineral compositions in Perple_X allowed the construction of a P-T path showing a steep, cool prograde metamorphic gradient of 2 °C/km to reach peak conditions of 5.8 GPa and 890 °C for the kyanite eclogite. The kyanite-out reaction formed bimineralic eclogite and is probably an integral part of the mineralogical evolution of most archetypal bimineralic eclogites at Roberts Victor and potentially elsewhere. The kyanite-out reaction occured at close to peak pressure (5.3 GPa) and was associated with a rise in temperature to 1380 °C. Mass balance calculations show that upon breakdown, the kyanite component is fully accommodated in garnet and omphacite via a reaction system with low water fugacity that required restricted fluid influx from metasomatic sources. The ?18O values of garnets are consistently higher than normal mantle values. Each sample has its characteristic trend of ?18O variance between garnets in the kyanite-bearing sections and those in the bimineralic parts covering a range between 5.1‰ and 6.8‰. No systematic change in O-isotope signature exists across the sample population. Differences in garnet trace element signatures between differing lithologies in the eclogites are significant. Grossular-rich garnets coexisting with kyanite have strong positive Eu-anomalies and low Gd/Yb ratios, while more pyrope-rich garnets in the bimineralic sections have lost their positive Eu-anomaly, have higher Gd/Yb ratios and generally higher heavy rare earth element contents. Garnets in the original kyanite-bearing portions thus reflect the provenance of the rocks as metamorphosed gabbros/troctolites. The kyanite-out reaction was most likely triggered by a heating event in the subcratonic lithosphere. As kyanite contains around 100 ppm of H2O it is suggested that the kyanite-out reaction, once initiated by heating and restricted metasomatic influx, was promoted by the release of water contained in the kyanite. The steep (high-P low-T) prograde P-T path defining rapid compression at low heating rates is atypical for subduction transport of eclogites into the lithospheric mantle. Such a trajectory is best explained in a model where strong lateral compression forces eclogites downward to higher pressures, supporting models of cratonic lithosphere formation by lateral collision and compression.
DS201706-1064
2017
Pearson, D.G.Bragagni, A., Luguet, A., Fonsecca, R.O.C., Pearson, D.G., Lorand, D.G., Nowell, G.M., Kjarsgaard, B.A.The geological record of base metal sulfides in the cratonic mantle: a microscale 187Os/188/Os study of peridotite xenoliths from Somerset Island, Rae craton,( Canada).Geochimica et Cosmochimica Acta, in press available 49p.Canada, Nunavut, Somerset Islandperidotite

Abstract: We report detailed petrographic investigations along with 187Os/188Os data in Base Metal Sulfide (BMS) on four cratonic mantle xenoliths from Somerset Island (Rae Craton, Canada). The results shed light on the processes affecting the Re-Os systematics and provide time constraints on the formation and evolution of the cratonic lithospheric mantle beneath the Rae craton. When devoid of alteration, BMS grains mainly consist of pentlandite + pyrrhotite ± chalcopyrite. The relatively high BMS modal abundance of the four investigated xenoliths cannot be reconciled with the residual nature of these peridotites, but requires addition of metasomatic BMS. This is especially evident in the two peridotites with the highest bulk Pd/Ir and Pd/Pt. Metasomatic BMS likely formed during melt/fluid percolation in the Sub Continental Lithospheric Mantle (SCLM) as well as during infiltration of the host kimberlite magma, when djerfisherite crystallized around older Fe-Ni-sulfides. On the whole-rock scale, kimberlite metasomatism is visible in a subset of bulk xenoliths, which defines a Re-Os errorchron that dates the host magma emplacement. The 187Os/188Os measured in the twenty analysed BMS grains vary from 0.1084 to >0.17 and it shows no systematic variation depending on the sulfide mineralogical assemblage. The largest range in 187Os/188Os is observed in BMS grains from the two xenoliths with the highest Pd/Ir, Pd/Pt, and sulfide modal abundance. The whole-rock TRD ages of these two samples underestimate the melting age obtained from BMS, demonstrating that bulk Re-Os model ages from peridotites with clear evidence of metasomatism should be treated with caution. The TRD ages determined in BMS grains are clustered around 2.8-2.7, ?2.2 and ?1.9 Ga. The 2.8-2.7 Ga TRD ages document the main SCLM building event in the Rae craton, which is likely related to the formation of the local greenstone belts in a continental rift setting. The Paleoproterozoic TRD ages can be explained by addition of metasomatic BMS during (i) major lithospheric rifting at ?2.2 Ga and (ii) the Taltson-Thelon orogeny at ?1.9 Ga. The data suggest that even metasomatic BMS can inherit 187Os/188Os from their original mantle source. The lack of isotopic equilibration, even at the micro-scale, allowed the preservation of different populations of BMS grains with distinct 187Os/188Os, providing age information on multiple magmatic events that affected the SCLM.
DS201707-1380
2016
Pearson, D.G.Wang, H., van Hunen, J., Pearson, D.G.Making Archean cratonic roots by lateral compression: a two stage thickening and stabilization model.Tectonophysics, in press availableMantlecraton

Abstract: Archean tectonics was capable of producing virtually indestructible cratonic mantle lithosphere, but the dominant mechanism of this process remains a topic of considerable discussion. Recent geophysical and petrological studies have refuelled the debate by suggesting that thickening and associated vertical movement of the cratonic mantle lithosphere after its formation are essential ingredients of the cratonization process. Here we present a geodynamical study that focuses on how the thick stable cratonic lithospheric roots can be made in a thermally evolving mantle. Our numerical experiments explore the viability of a cratonization process in which depleted mantle lithosphere grows via lateral compression into a > 200-km thick, stable cratonic root and on what timescales this may happen. Successful scenarios for craton formation, within the bounds of our models, are found to be composed of two stages: an initial phase of tectonic shortening and a later phase of gravitational self-thickening. The initial tectonic shortening of previously depleted mantle material is essential to initiate the cratonization process, while the subsequent gravitational self-thickening contributes to a second thickening phase that is comparable in magnitude to the initial tectonic phase. Our results show that a combination of intrinsic compositional buoyancy of the cratonic root, rapid cooling of the root after shortening, and the long-term secular cooling of the mantle prevents a Rayleigh-Taylor type collapse, and will stabilize the thick cratonic root for future preservation. This two-stage thickening model provides a geodynamically viable cratonization scenario that is consistent with petrological and geophysical constraints.
DS201708-1564
2017
Pearson, D.G.Abersteiner, A., Kamanetsky, V.S., Pearson, D.G., Kamenetsky, M., Ehrig, K., Goemann, K., Rodemann, T.Monticellite in group I kimberlites: implications for evolution of parallel melts and post emplacement CO2 degassing. Leslie, Pipe 1Chemical Geology, in press available, 54p.Canada, Northwest Territories, Europe, Finlanddeposit, Leslie

Abstract: Monticellite is a magmatic and/or deuteric mineral that is often present, but widely varying in concentrations in Group-I (or archetypal) kimberlites. To provide new constraints on the petrogenesis of monticellite and its potential significance to kimberlite melt evolution, we examine the petrography and geochemistry of the minimally altered hypabyssal monticellite-rich Leslie (Canada) and Pipe 1 (Finland) kimberlites. In these kimberlites, monticellite (Mtc) is abundant (25–45 vol%) and can be classified into two distinct morphological types: discrete and intergrown groundmass grains (Mtc-I), and replacement of olivine (Mtc-II). Monticellite in group-I kimberlites: Implications for evolution of parental melts and post-emplacement CO 2 degassing (PDF Download Available).
DS201709-1991
2017
Pearson, D.G.Goodarzi, P.Y., Berry, A.J., Pearson, D.G., Yaxley, G.M., Newville, M.Garnet as a recorder of metasomatism in the sub-continental lithospheric mantle. Goldschmidt Conference, abstract 1p.Africa, Namibiadeposit , Louwerensia

Abstract: Metasomatism by fluid or melt is commonly attributed as the cause of chemical and modal heterogeneity observed in peridotite xenoliths from the sub-continental lithospheric mantle. Documented manifestations are (1) perturbation of the oxygen fugacity (fO2), which may affect the stability of carbon-bearing phases, and (2) trace-element enrichment, typified by the shape of REEN patterns. Garnet, which contains Fe2+ and Fe3+ in measurable quantities, and exhibits prominent variation in REEN patterns between samples, may record the metasomatic history of the mantle. Here we report variations of fO2 and trace element concentrations for a suite of 22 garnet-bearing peridotite xenoliths from the Louwrensia kimberlite, south-central Namibia. The xenoliths span an estimated pressure range between 2.7 and 4.5 GPa. Fe3+/?Fe of garnet was determined by Fe K-edge XANES spectroscopy. Concomitant fO2 was calculated using the oxybarometer calibration of Miller et al. [1]. The trace element concentrations of all phases were determined by LA-ICP-MS. A global dataset comprising 454 garnet REEN patterns from 19 kimberlites has been compiled. The REEN pattern of each sample was fit to orthogonal polynomial functions that parameterise the abundance, slope, quadratic curvature, and cubic curvature [2]. Quadratic and cubic curvature correlate with abundance, albeit with considerable scatter. There is, however, an absence of correlation between REEN patterns and fO2, depth, or modal abundance. This is in contrast to correlations and trends observed for basaltic melts that clearly identify petrogenetic trends. The partitioning of REEs between garnet and co-existing phases in these samples highlights pronounced trace-element disequilibrium and hence question the validity of considering garnet REEN in isolation as a means of discerning metasomatic history
DS201709-2016
2017
Pearson, D.G.Kjarsgaard, B.A., Heaman, L.M., Sarkar, C., Pearson, D.G.The North American mid-Cretaceous kimberlite corridor: wet, edge-driven decompression melting of an OIB-type deep mantle source.Geochemistry, Geophysics, Geosystems: G3, Vol. 18, 7, pp. 2727-2747.Canada, Somerset Island, Saskatchewan, United States, Kansasmagmatism, convection, diamond genesis

Abstract: Thirty new high-precision U-Pb perovskite and zircon ages from kimberlites in central North America delineate a corridor of mid-Cretaceous (115–92 Ma) magmatism that extends ?4000 km from Somerset Island in Arctic Canada through central Saskatchewan to Kansas, USA. The least contaminated whole rock Sr, Nd, and Hf isotopic data, coupled with Sr isotopic data from groundmass perovskite indicates an exceptionally limited range in Sr-Nd-Hf isotopic compositions, clustering at the low ?Nd end of the OIB array. These isotopic compositions are distinct from other studied North American kimberlites and point to a sublithospheric source region. This mid-Cretaceous kimberlite magmatism cannot be related to mantle plumes associated with the African or Pacific large low-shear wave velocity province (LLSVP). All three kimberlite fields are adjacent to strongly attenuated lithosphere at the edge of the North American craton. This facilitated edge-driven convection, a top-down driven processes that caused decompression melting of the transition zone or overlying asthenosphere. The inversion of ringwoodite and/or wadsleyite and release of H2O, with subsequent metasomatism and synchronous wet partial melting generates a hot CO2 and H2O-rich protokimberlite melt. Emplacement in the crust is controlled by local lithospheric factors; all three kimberlite fields have mid-Cretaceous age, reactivated major deep-seated structures that facilitated kimberlite melt transit through the lithosphere.
DS201709-2048
2017
Pearson, D.G.Reimink, J.R., Carlson, R.W., Shirey, S.B., Pearson, D.G.Crustal evolution of the Archean Slave craton, NWT.Goldschmidt Conference, abstract 1p.Canada, Northwest Territoriesgeochronology

Abstract: The Slave craton, located in the northwestern portion of the Canadian Shield, contains the oldest known remnant of evolved crust on Earth [1?3] and more extensive suites of granitoid basement gneisses with crystallization ages that nearly span the breadth of the Archean. Portions of these basement gneisses form the Central Slave Basement Complex (CSBC), a belt of exposures recording magmatic events that occurred approximately every 100?150 million years from 3.5?2.7 Ga [4]. When considered with the 4.02 Ga Acasta Gneiss Complex, the good exposure and wide age range of basement gneisses of the Slave craton provide a unique record of the geological processes involved in continent formation. A suite of 3.5?2.7 gyr old Slave craton granitoids collected from a 200 km-long traverse of the CSBC has intermediate to felsic compositions, textures that range from migmatitic gneisses to preservation of primary magmatic features. Preliminary Sm-Nd isotope systematics, as well as zircon U-Pb and Hf isotope data suggest that the granitoids reflect both the products of reworking of Hadean crust, as indicated by the presence of 142Nd deficits in some of the units, but also new additions from the mantle as indicated both in the chemical composition and initial isotopic composition of other rock units. For those samples that derive from remelting of older crustal materials, the initial Hf isotopic composition of zircons are most consistent with a source component that includes Hadean mafic crust. The multiple U-Pb age peaks documented by accessory minerals show a close correspondence with age spectra from the welldocumented mantle lithosphere beneath this region [5] illustrating the coupled evolution of crust and mantle.
DS201709-2056
2017
Pearson, D.G.Sommer, H., Jacob, D.E., Stern, R.A., Petts, D., Mattey, D.P., Pearson, D.G.Fluid induced transition from banded kyanite to bimineralic eclogite and implications for the evolution of cratons.Goldschmidt Conference, abstract 1p.Africa, South Africadeposit - Roberts Victor

Abstract: Heterogeneous, modally banded kyanite-bearing and bimineralic eclogites from the lithospheric mantle, collected at the Roberts Victor Diamond mine (South Africa), show a reaction texture in which kyanite is consumed. Geothermobarometric calculations using measured mineral compositions in Perple_X allowed the construction of a P-T path showing a steep, cool prograde metamorphic gradient of 2 °C/km to reach peak conditions of 5.8 GPa and 890 °C for the kyanite eclogite. The kyanite-out reaction formed bimineralic eclogite and is probably an integral part of the mineralogical evolution of most archetypal bimineralic eclogites at Roberts Victor and potentially elsewhere. The kyanite-out reaction occured at close to peak pressure (5.3 GPa) and was associated with a rise in temperature to 1380 °C. Mass balance calculations show that upon breakdown, the kyanite component is fully accommodated in garnet and omphacite via a reaction system with low water fugacity that required restricted fluid influx from metasomatic sources. The ?18O values of garnets are consistently higher than normal mantle values. Each sample has its characteristic trend of ?18O variance between garnets in the kyanite-bearing sections and those in the bimineralic parts covering a range between 5.1‰ and 6.8‰. No systematic change in O-isotope signature exists across the sample population. Differences in garnet trace element signatures between differing lithologies in the eclogites are significant. Grossular-rich garnets coexisting with kyanite have strong positive Eu-anomalies and low Gd/Yb ratios, while more pyrope-rich garnets in the bimineralic sections have lost their positive Eu-anomaly, have higher Gd/Yb ratios and generally higher heavy rare earth element contents. Garnets in the original kyanite-bearing portions thus reflect the provenance of the rocks as metamorphosed gabbros/troctolites. The kyanite-out reaction was most likely triggered by a heating event in the subcratonic lithosphere. As kyanite contains around 100 ppm of H2O it is suggested that the kyanite-out reaction, once initiated by heating and restricted metasomatic influx, was promoted by the release of water contained in the kyanite. The steep (high-P low-T) prograde P-T path defining rapid compression at low heating rates is atypical for subduction transport of eclogites into the lithospheric mantle. Such a trajectory is best explained in a model where strong lateral compression forces eclogites downward to higher pressures, supporting models of cratonic lithosphere formation by lateral collision and compression.
DS201709-2063
2017
Pearson, D.G.Thomassot, E., Pearson, D.G., Kitayama, Y., Deloule, E.Sulfur isotope signature 33S/34S and 36S of sea water altered Archean oceanic crust in Siberia eclogite.Goldschmidt Conference, abstract 1p.Russia, Siberiaeclogites

Abstract: Eclogite xenoliths brought to the surface by kimberlites are high pressure mafic rocks whose origin (magmatic vs crustal) remains debated. In addition to disagreement on how to interpret eclogite compositions, mantle metasomatism overprints the mineralogy and geochemistry of some of these rocks, making the question of their protolith undoubtedly more complex. In this contribution we aim to test the robustness of multiple S-isotope signatures in highly metasomatized eclogitic sulfides. We selected 12 interstitial sulfides from Mir (n=4) and Udachnaya (n=8) eclogites, intergrown with garnet and omphacite. We analysed their lead (including Pb204) and S-isotope (32S, 33S, 34S and 36S) compositions, insitu, using a Cameca ims 1280. The samples consist of complex assemblages of pyrrhotite pentlandite intergrowth with K- and Cl-rich sulfides (djerfisherite) invaded by veinlets of alteration minerals (mainly chlorite). All our samples display internal zoning in Pb concentration (118 ppm to 4.2 wt%) but are homogeneous in isotopic compositions (e.g. 208Pb/204Pb = 38.09 ± 0.35‰). Pb-Pb ages of eclogitic sulfides are modern and undoubtedly reflect the metasomatic overprint by a Cl- and K-rich kimberlitic melt (consistent with the presence of djerfisherite). Sulfur isotope signatures of these sulfide (G34S = -1.3‰ ±2‰) fall within the canonical mantle range and cannot be distinguished from the composition of sulfides in the kimberlite (-1.4 ±2.2‰, Kitayama et al., 2016). Furthermore, Mir and Udachanaya eclogitic sulfides carry the largest mass independant fractionation (MIF) ever reported in mantle rocks. The overall trend reveals negative ?33S (down to - 1.1‰) associated to positive ?36S (up to 3‰). This observed correlation between ?33S and ?36S is consistent with the composition of sulfate aerosols formed in the Archean by photolysis reactions and likely dissolved in the ocean [4]. Our results indicate that multiple sulfur isotopes survive intense metasomatism (because isotope fractionation does not create S-MIF), and provide further evidence that the protoliths of Siberian eclogites were mafic rocks altered by seawater in the Archean.
DS201710-2217
2017
Pearson, D.G.Bragagni, A., Luguet, A., Fonseca, R.O.C., Pearson, D.G.,Lorand, J-P., Nowell, G.M., Kjarsgaard, B.A.The geological record of base metal sulfides in the cratonic mantle: a microscale 187Os/188Os study of peridotite xenoliths from Somerset Island, Rae Craton ( Canada).Geochimica et Cosmochimia Acta, Vol. 216, pp. 264-285.Canada, Nunavut, Somerset IslandGeochronology

Abstract: We report detailed petrographic investigations along with 187Os/188Os data in Base Metal Sulfide (BMS) on four cratonic mantle xenoliths from Somerset Island (Rae Craton, Canada). The results shed light on the processes affecting the Re-Os systematics and provide time constraints on the formation and evolution of the cratonic lithospheric mantle beneath the Rae craton. When devoid of alteration, BMS grains mainly consist of pentlandite + pyrrhotite ± chalcopyrite. The relatively high BMS modal abundance of the four investigated xenoliths cannot be reconciled with the residual nature of these peridotites, but requires addition of metasomatic BMS. This is especially evident in the two peridotites with the highest bulk Pd/Ir and Pd/Pt. Metasomatic BMS likely formed during melt/fluid percolation in the Sub Continental Lithospheric Mantle (SCLM) as well as during infiltration of the host kimberlite magma, when djerfisherite crystallized around older Fe-Ni-sulfides. On the whole-rock scale, kimberlite metasomatism is visible in a subset of bulk xenoliths, which defines a Re-Os errorchron that dates the host magma emplacement. The 187Os/188Os measured in the twenty analysed BMS grains vary from 0.1084 to >0.17 and it shows no systematic variation depending on the sulfide mineralogical assemblage. The largest range in 187Os/188Os is observed in BMS grains from the two xenoliths with the highest Pd/Ir, Pd/Pt, and sulfide modal abundance. The whole-rock TRD ages of these two samples underestimate the melting age obtained from BMS, demonstrating that bulk Re-Os model ages from peridotites with clear evidence of metasomatism should be treated with caution. The TRD ages determined in BMS grains are clustered around 2.8-2.7, ?2.2 and ?1.9 Ga. The 2.8-2.7 Ga TRD ages document the main SCLM building event in the Rae craton, which is likely related to the formation of the local greenstone belts in a continental rift setting. The Paleoproterozoic TRD ages can be explained by addition of metasomatic BMS during (i) major lithospheric rifting at ?2.2 Ga and (ii) the Taltson-Thelon orogeny at ?1.9 Ga. The data suggest that even metasomatic BMS can inherit 187Os/188Os from their original mantle source. The lack of isotopic equilibration, even at the micro-scale, allowed the preservation of different populations of BMS grains with distinct 187Os/188Os, providing age information on multiple magmatic events that affected the SCLM.
DS201712-2688
2017
Pearson, D.G.Harris, G.A., Pearson, D.G., Liu, J., Hardman, M.F., Kelsch, D.Mantle composition, age and geotherm beneath the Darby kimberlite field, west central Rae craton.45th. Annual Yellowknife Geoscience Forum, p. 33 abstractCanada, Northwest Territoriesdeposit - Darby

Abstract: New geological and geophysical research on Canada’s Rae craton are providing an increasingly good baseline for diamond exploration. This study uses mantle xenoliths and xenocrysts from the Darby property, located ~200 km southwest of the community of Kugaaruk, Nunavut, to provide new information on the lithospheric mantle and diamond potential of the western portion of the central Rae. Peridotite xenoliths containing enough fresh olivine have a median Mg# value of 92.5, indistinguishable from the median value of 92.6 typical of cratonic peridotites world-wide. Only of the 14 peridotitic xenoliths contain fresh garnet. Of these, garnet in one sample is classified as harzburgitic (G10), giving a minimum pressure of 4.7 GPa using the P38 geobarometer (38 mW/m2 model geothermal gradient), while garnets from three peridotites are classified as lherzolitic (G9). 52 garnets picked from concentrate have lherzolitic affinities. Lherzolitic diopsides from kimberlite heavy mineral concentrate yield a lithospheric thickness of ~ 200 km. The four garnet peridotite xenoliths and 49 peridotitic garnets from concentrate yield two distinct modes in mantle sampling depths using Ni thermometry, when projected to the Cpx geotherm. A cluster of samples from the higher Ca/Cr lherzolitic garnets equilibrated at 765 to 920 °C with a group of peridotitic garnets (50 % of xenoliths and 28 % of concentrate) from the lower Ca/Cr lherzolitic garnets with anomalously high Ti concentrations yielding super-adiabatic TNi values The aluminum-in-olivine thermometer applied to olivines filtered to be “garnet facies yielded a mantle sampling portion of the mantle cargo from the diamond stability field. A suite of pyroxenitic xenoliths are a feature of each Darby kimberlite target. New screening techniques indicate that these rocks likely originate close to the crust mantle boundary. Osmium isotope analyses of the Darby peridotites reveal whole-rock Re-depletion ages ranging from Mesoarchean to Paleoproterozoic. The pyroxenite xenoliths have very radiogenic Os isotope compositions and provide the first age information from pyroxenites/“eclogites” beneath the Rae craton. Their resulting Archean whole rock TMA ages are consistent with a Mesoarchean age of the western Central Rae lithosphere older than the lithosphere beneath the Repulse Bay block in the East section of the Rae craton (Liu et al., 2016. Precambrian Research 272). The highly depleted olivine compositions, thick cold lithosphere, and Archean ages of the Darby peridotite xenoliths clearly indicate the presence of 200 km thick cold cratonic lithospheric mantle beneath the western segment of the central Rae craton circa 540 Ma. The Archean model ages of most of the pyroxenites support this, notwithstanding the fact that some of these rocks could be sampling either crust or mantle lithologies very close to the crust-mantle boundary. Mantle sampling took place well into the diamond stability field at Darby.
DS201801-0078
2017
Pearson, D.G.Wang, H., van Hunen, J., Pearson, D.G.Making Archean cratonic roots by lateral compression: a two stage thickening and stabilization model.Tectonophysics, in press available, 10p.Mantlecraton

Abstract: Making Archean cratonic roots by lateral compression: a two stage thickening and stabilization model.
DS201802-0217
2018
Pearson, D.G.Abersteiner, A., Kamenetsky, V.S., Pearson, D.G., Kamenetsky, M., Goemann, K., Ehrig, K., Rodemann, T.Monticellite in group I kimberlites: implications for evolution of parental melts and post emplacement CO2 degassing.Chemical Geology, Vol. 478, pp. 76-88.Canada, Northwest Territories, Europe, Finlanddeposit - Leslie, Pipe 1

Abstract: Monticellite is a magmatic and/or deuteric mineral that is often present, but widely varying in concentrations in Group-I (or archetypal) kimberlites. To provide new constraints on the petrogenesis of monticellite and its potential significance to kimberlite melt evolution, we examine the petrography and geochemistry of the minimally altered hypabyssal monticellite-rich Leslie (Canada) and Pipe 1 (Finland) kimberlites. In these kimberlites, monticellite (Mtc) is abundant (25-45 vol%) and can be classified into two distinct morphological types: discrete and intergrown groundmass grains (Mtc-I), and replacement of olivine (Mtc-II). Primary multiphase melt inclusions in monticellite, perovskite and Mg-magnetite contain assemblages dominated by alkali (Na, K, Ba, Sr)-enriched Ca-Mg-carbonates, chlorides, phosphates, spinel, silicates (e.g. olivine, phlogopite) and sulphides. These melt inclusions probably represent snapshots of a variably differentiated kimberlite melt that evolved in-situ towards carbonatitic and silica-poor compositions. Although unconstrained in their concentration, the presence of alkali-carbonates and chlorides in melt inclusions suggests they are a more significant component of the kimberlite melt than commonly recorded by whole-rock analyses. We present petrographic and textural evidence showing that pseudomorphic Mtc-II resulted from an in-situ reaction between olivine and the carbonate component of the kimberlite melt in the decarbonation reactio. This reaction is supported by the preservation of abundant primary inclusions of periclase and to a lesser extent Fe-Mg-oxides in monticellite, perovskite and Mg-magnetite. Based on the preservation of primary periclase inclusions, we infer that periclase also existed in the groundmass, but was subsequently altered to brucite. We suggest that CO2 degassing in the latter stages of kimberlite emplacement into the crust is largely driven by the observed reaction between olivine and the carbonate melt. For this reaction to proceed, CO2 should be removed (i.e. degassed), which will cause further reaction and additional degassing in response to this chemical system change (Le Chatelier's principle). Our study demonstrates that these proposed decarbonation reactions may be a commonly overlooked process in the crystallisation of monticellite and exsolution of CO2, which may in turn contribute to the explosive eruption and brecciation processes that occur during kimberlite magma emplacement and pipe formation.
DS201802-0234
2018
Pearson, D.G.From, R.E., Camacho, A., Pearson, D.G., Luo, Y.U-Pb and Lu-Hf isotopes of the Archean orthogneiss complex on eastern Hall Peninsula, southern Baffin Island, Nunavut: identification of exotic Paleo to Mesoarchean crust beneath eastern Hall Peninsula.Precambrian Research, Vol. 305, pp. 341-357.Canada, Nunavut, Hall Peninsulageochronology

Abstract: Eastern Hall Peninsula on southeastern Baffin Island, lies at the junction of a complex Paleoproterozoic collision between the Rae craton, Meta Incognita microcontinent and the North Atlantic craton from ca. 1.88 to 1.80?Ga. Several different interpretations of crustal correlations and the location of intervening sutures have been proposed based on reconnaissance-scale geologic investigation. Therefore, in this study, complex zircon grains from Archean orthogneiss units on eastern Hall Peninsula were analyzed in-situ to elucidate the detailed magmatic history of the region and assess crustal provenance. Magmatic zircons yielded U-Pb crystallization ages between ca. 2976 and 2720?Ma and metamorphic zircons record tectonothermal disturbances between ca. 2740 and 2700?Ma, a period coinciding with metamorphism documented in adjacent crustal blocks (e.g., west Greenland and northern Labrador). Magmatic rocks older than ca. 2740?Ma generally have positive ?Hf(t) signatures between 0 and 7 (±2) and depleted mantle model ages of ca. 3.1-3.0?Ga indicating the time that protolith melt was extracted from the mantle. The oldest, granodioritic crust crystallized at ca. 2976?Ma and was then reworked periodically at ca. 2.93, 2.84-2.81 and 2.77-2.69?Ma. Zircons from two orthogneiss samples, with U-Pb crystallization ages younger than ca. 2740?Ma, yielded negative ?Hf(t) values ranging from ?4 to ?12 and mean depleted mantle model ages of ca. 3.4 and 3.3?Ga respectively, indicating derivation from an older, potentially exotic, crustal source yet to be identified in outcrop on Hall Peninsula. Synthesizing regional U-Pb data we propose a new regional correlation model that retains the essentials of previous models and incorporates new data from eastern Hall Peninsula and other recent studies. This new tectonic correlation model groups eastern Hall Peninsula, southern Cumberland Peninsula and the Aasiaat domain into a “Core zone” that shared a geologic history prior to 1.90?Ga and potentially prior to 2.75?Ga.
DS201802-0241
2018
Pearson, D.G.Hardman, M.F., Pearson, D.G., Stachel, T., Sweeney, R.J.Statistical approaches to the discrimination of crust and mantle derived low Cr garnet - Major element based methods and their application to diamond exploration.Journal of Geochemical Exploration, Vol. 186, pp. 24-35.Mantlegarnet diamond exploration

Abstract: In diamond exploration, the accurate distinction between garnets from the crust or mantle, or from those having a cognate origin with kimberlite (low-Cr megacrysts), is important for the assessment of indicator mineral samples; misclassifications potentially result in costly misdirection of exploration efforts. Existing literature databases and graphical classification schemes for garnets suffer from a paucity of craton-derived, lower-crustal garnets that - as shown here - are among the most difficult to distinguish from garnets of mantle origin. To improve this situation, a large database of new and literature garnet major element analyses has been compiled. Using this dataset, it is shown that the conventionally used Mg# (Mg/(Mg + Fe)) vs. Ca# (Ca/(Mg + Ca)) plot (Schulze, 2003) for discrimination of crust and mantle garnets results in significant overlap (39.2% crustal failure rate using our dataset). We propose a new graphical classification scheme that uses the parameters ln(Ti/Si) and ln(Mg/Fe) to discriminate low-Cr garnets of crust origin from those of a mantle eclogite-pyroxenite origin with an error rate of 10.1 ± 2.1% at the 95% confidence level (assessed via K-fold cross-validation with ten random test datasets), significantly lower than existing methods. Multivariate statistical solutions, which incorporate a wide selection of geochemical variables, represent additional possibilities for discrimination. Using our new database, logistic regression (LR) and linear discriminant analysis (LDA) approaches are evaluated and new crust-mantle garnet discrimination schemes derived. The resulting solutions, using a wide variety of cations in garnet, provide lower misclassification rates than existing literature schemes. Both LR and LDA are successful discrimination techniques with error rates for the discrimination of crust from mantle eclogite-pyroxenite of 7.5 ± 1.9% and 8.2 ± 2.3%, respectively. LR, however, involves fewer stipulations about the distribution of training data (i.e., it is more "robust") and can return an estimate for probability of classification certainty for single garnets. New data from diamond exploration programs can be readily classified using these new graphical and statistical methods. As the discrimination of low-Cr megacrysts from mantle eclogite-pyroxenite is not the focus of this study, we recommend the method of Schulze (2003) or Grütter et al. (2004) for low-Cr megacryst discrimination to identify megacrysts in the "mantle" suite. Runstreams for our LDA and LR approaches using the freeware "R" are provided for quick implementation.
DS201804-0714
2018
Pearson, D.G.Korolev, N.M., Kopylova, M., Bussweiller, Y., Pearson, D.G., Gurney, J., Davidson, J.The uniquely high temperature character of Culli nan diamonds: a signature of the Bushveld mantle plume?Lithos, Vol. 304, pp. 362-373.Africa, South Africadeposit - Cullinan

Abstract: The mantle beneath the Cullinan kimberlite (formerly known as "Premier") is a unique occurrence of diamondiferous cratonic mantle where diamonds were generated contemporaneously and shortly following a mantle upwelling that led to the formation of a Large Igneous Province that produced the world's largest igneous intrusion - the 2056?Ma Bushveld Igneous Complex (BIC). We studied 332 diamond inclusions from 202 Cullinan diamonds to investigate mantle thermal effects imposed by the formation of the BIC. The overwhelming majority of diamonds come from three parageneses: (1) lithospheric eclogitic (69%), (2) lithospheric peridotitic (21%), and (3) sublithospheric mafic (9%). The lithospheric eclogitic paragenesis is represented by clinopyroxene, garnet, coesite and kyanite. Main minerals of the lithospheric peridotitic paragenesis are forsterite, enstatite, Cr-pyrope, Cr-augite and spinel; the sublithospheric mafic association includes majorite, CaSiO3 phases and omphacite. Diamond formation conditions were calculated using an Al-in-olivine thermometer, a garnet-clinopyroxene thermometer, as well as majorite and Raman barometers. The Cullinan diamonds may be unique on the global stage in recording a cold geotherm of 40?mW/m2 in cratonic lithosphere that was in contact with underlying convecting mantle at temperatures of 1450-1550?°C. The studied Cullinan diamonds contain a high proportion of inclusions equilibrated at temperatures exceeding the ambient 1327?°C adiabat, i.e. 54% of eclogitic diamonds and 41% of peridotitic diamonds. By contrast, ? 1% of peridotitic diamond inclusions globally yield equally high temperatures. We propose that the Cullinan diamond inclusions recorded transient, slow-dissipating thermal perturbations associated with the plume-related formation of the ~2?Ga Bushveld igneous province. The presence of inclusions in diamond from the mantle transition zone at 300-650?km supports this view. Cullinan xenoliths indicative of the thermal state of the cratonic lithosphere at ~1.2?Ga are equilibrated at the relatively low temperatures, not exceeding adiabatic. The ability of diamonds to record super-adiabatic temperatures may relate to their entrainment from the deeper, hotter parts of the upper mantle un-sampled by the kimberlite in the form of xenoliths or their equilibration in a younger lithosphere after a decay of the thermal disturbance.
DS201804-0723
2018
Pearson, D.G.Nestola, F., Korolev, N., Kopylova, M., Rotiroti, N., Pearson, D.G., Pamato, M.G., Alvaro, M., Peruzzo, L., Gurney, J.J., Moore, A.E., Davidson, J.CaSiO3 perovskite in diamond indicates the recycling of oceanic crust into the lower mantle.Nature, Vol. 555, March 8, pp. 237-241.Mantledeposit - Cullinan

Abstract: Laboratory experiments and seismology data have created a clear theoretical picture of the most abundant minerals that comprise the deeper parts of the Earth’s mantle. Discoveries of some of these minerals in ‘super-deep’ diamonds—formed between two hundred and about one thousand kilometres into the lower mantle—have confirmed part of this picture1,2,3,4,5. A notable exception is the high-pressure perovskite-structured polymorph of calcium silicate (CaSiO3). This mineral—expected to be the fourth most abundant in the Earth—has not previously been found in nature. Being the dominant host for calcium and, owing to its accommodating crystal structure, the major sink for heat-producing elements (potassium, uranium and thorium) in the transition zone and lower mantle, it is critical to establish its presence. Here we report the discovery of the perovskite-structured polymorph of CaSiO3 in a diamond from South African Cullinan kimberlite. The mineral is intergrown with about six per cent calcium titanate (CaTiO3). The titanium-rich composition of this inclusion indicates a bulk composition consistent with derivation from basaltic oceanic crust subducted to pressures equivalent to those present at the depths of the uppermost lower mantle. The relatively ‘heavy’ carbon isotopic composition of the surrounding diamond, together with the pristine high-pressure CaSiO3 structure, provides evidence for the recycling of oceanic crust and surficial carbon to lower-mantle depths.https://www.nature.com/articles/nature25972
DS201804-0726
2018
Pearson, D.G.Pearson, D.G.Making and stabilising the deep diamond bearing roots of continents.4th International Diamond School: Diamonds, Geology, Gemology and Exploration Bressanone Italy Jan. 29-Feb. 2nd., pp. 33-35. abstractMantlecraton - peridotites
DS201804-0735
2018
Pearson, D.G.Shirey, S.B., Pearson, D.G.How to obtain and interpret diamond ages.4th International Diamond School: Diamonds, Geology, Gemology and Exploration Bressanone Italy Jan. 29-Feb. 2nd., pp. 38-40. abstractTechnologydiamond ages
DS201807-1482
2018
Pearson, D.G.Bussweiler, Y., Pearson, D.G., Stachel, T., Kjarsgaard, B.A.Cr-rich megacrysts of clinopyroxene and garnet from Lac de Gras kimberlites, Slave Craton, Canada - implications for the origin of clinopyroxene and garnet in cratonic lherzolites.Mineralogy and Petrology, 10.1007/s00710 -018-0599-2, 14p. Canada, Northwest Territoriesdeposit - Diavik, Ekati

Abstract: Kimberlites from the Diavik and Ekati diamond mines in the Lac de Gras kimberlite field contain abundant large (>1 cm) clinopyroxene (Cr-diopside) and garnet (Cr-pyrope) crystals. We present the first extensive mineral chemical dataset for these megacrysts from Diavik and Ekati and compare their compositions to cratonic peridotites and megacrysts from the Slave and other cratons. The Diavik and Ekati Cr-diopside and Cr-pyrope megacrysts are interpreted to belong to the Cr-rich megacryst suite. Evidence for textural, compositional, and isotopic disequilibrium suggests that they constitute xenocrysts in their host kimberlites. Nevertheless, their formation may be linked to extensive kimberlite magmatism and accompanying mantle metasomatism preceding the eruption of their host kimberlites. It is proposed that the formation of megacrysts may be linked to failed kimberlites. In this scheme, the Cr-rich megacrysts are formed by progressive interaction of percolating melts with the surrounding depleted mantle (originally harzburgite). As these melts percolate outwards, they may contribute to the introduction of clinopyroxene and garnet into the depleted mantle, thereby forming lherzolite. This model hinges on the observation that lherzolitic clinopyroxenes and garnets at Lac de Gras have compositions that are strikingly similar to those of the Cr-rich megacrysts, in terms of major and trace elements, as well as Sr isotopes. As such, the Cr-rich megacrysts may have implications for the origin of clinopyroxene and garnet in cratonic lherzolites worldwide.
DS201807-1495
2018
Pearson, D.G.Gress, M.U., Pearson, D.G., Chinn, I.L., Koornneef, J.M., Pals, A.S.M., Van der Valk, E.A.S., Davies, G.R.Episodic eclogitic diamond genesis at Jwaneng diamond mine, Botswana.Goldschmidt2018, abstract 1p.Africa, Botswanadeposit - Jwaneng

Abstract: The diamondiferous Jwaneng kimberlite cluster (~240 Ma) is located on the NW rim of the Archaean Kaapvaal Craton in central Botswana. Previous studies report eclogitic diamond formation in the late Archean (2.9 Ga) and in the Middle Proterozoic (1.5 Ga) involving different mantle and sedimentary components [1;2;3]. Here we report newly acquired Sm- Nd ages of individual eclogitic pyrope-almandine and omphacite inclusions along with their major element data and nitrogen data from the diamond hosts to re-examine Jwaneng’s diamond formation ages. The Sm-Nd isotope analyses were performed via TIMS using 1013? resistors [4]. An initial suite of three pyropealmandine and 14 omphacite inclusions yield 143Nd/144Nd from 0.51102±7 to 0.5155±5. 147Sm/144Nd vary from 0.024 to 0.469. Major element data defines two inclusion populations: (1) seven omphacites with high Mg#, high Cr# and one pyropealmandine with low-Ca define an isochron age of 1.93±0.16 Ga with ?Ndi= +3.5; (2) seven omphacites with low Mg#, low Cr# and two pyrope-almandines with low-Ca define an isochron age of 0.82±0.06 Ga with ?Ndi= +3.7. Nitrogen contents of corresponding diamond host growth zones in Group (1) are ? 50 at.ppm whereas Group (2) range between 50 to 700 at.ppm with N-aggregation > 70 %B. Additional data used to define “co-genetic” inclusion suites include Sr-isotopes and trace elements of the inclusions and carbon isotopes of the diamond hosts. Re-Os data of coexisting sulphide inclusions from the same silicate-bearing diamonds further validates the ages and indicates more periods of diamond formation at Jwaneng than previously assumed. The integrated data indicate the possibility of an extensive Paleoproterozoic diamond-forming event in southern Africa.
DS201807-1525
2018
Pearson, D.G.Shu, Q., Brey, G.P., Pearson, D.G.Eclogites and garnet pyroxenites from Kimberley, Kaapvaal craton, South Africa: their diverse origins and complex metasomatic signatures.Mineralogy and Petrology, June 14, DOI:10.1007/ s00710-018 -0595-6, 16p.Africa, South Africadeposit - Boshof

Abstract: We describe the petrography and mineral chemistry of sixteen eclogite and garnet pyroxenite xenoliths from the reworked Boshof road dump (Kimberley) and define three groups that stem from different depths. Group A, the shallowest derived, has low HREE (heavy rare earth element) abundances, flat middle to heavy REE patterns and high Mg# [= 100•Mg/(Mg?+?Fe)]. Their protoliths probably were higher pressure cumulates (~ 0.7 GPa) of mainly clinopyroxene (cpx) and subordinate orthopyroxene (opx) and olivine (ol). Group B1 xenoliths, derived from the graphite/diamond boundary and below show similarities to present-day N-MORB that were modified by partial melting (higher Mg# and positively inclined MREE (middle REE) and HREE (heavy REE) patterns of calculated bulk rocks). Group B2 samples from greatest depth are unique amongst eclogites reported so far worldwide. The calculated bulk rocks have humped REE patterns with very low La and Lu and prominent maxima at Sm or Eu and anomalously high Na2O (up to 5 wt%) which makes protolith identification difficult. The complex trace element signatures of the full spectrum of Kimberley eclogites belie a multi-stage history of melt depletion and metasomatism with the introduction of new phases especially of phlogopite (phlog). Phlogopite appears to be characteristic for Kimberley eclogites and garnet peridotites. Modelling the metasomatic overprint indicates that groups A and B1 were overprinted by volatile- and potassium-rich melts probably by a process of chromatographic fractionation. Using constraints from other metasomatized Kimberley mantle rocks suggest that much of the metasomatic phlogopite in the eclogites formed during an intense episode of metasomatism that affected the mantle beneath this region 1.1 Gyr ago.
DS201808-1750
2018
Pearson, D.G.Hardman, M.F., Pearson, D.G., Stachel, T., Sweeney, R.J.Statistical approaches to the discrimination of mantle - and crust derived low Cr garnets using major and trace element data.Mineralogy and Petrology, doi.org/10.1007/s00710-018-0622-7 10p.Technologygarnet classification
DS201808-1751
2018
Pearson, D.G.Harris, G.A., Pearson, D.G., Liu, J., Hardman, M.F., Snyder, D.B., Kelsch, D.Mantle composition, age and geotherm beneath the Darby kimberlite field, west central Rae craton.Mineralogy and Petrology, doi.org/10.1007/s00710-018-0609-4 14p.Canada, Northwest Territoriesdeposit - Darby

Abstract: New geological and geophysical research on Canada’s Rae craton are providing an increasingly good baseline for diamond exploration. This study uses mantle xenoliths and xenocrysts from the Darby property, located ~200 km southwest of the community of Kugaaruk, Nunavut, to provide new information on the lithospheric mantle and diamond potential of the western portion of the central Rae. Peridotite xenoliths containing enough fresh olivine have a median Mg# value of 92.5, indistinguishable from the median value of 92.6 typical of cratonic peridotites world-wide. Only of the 14 peridotitic xenoliths contain fresh garnet. Of these, garnet in one sample is classified as harzburgitic (G10), giving a minimum pressure of 4.7 GPa using the P38 geobarometer (38 mW/m2 model geothermal gradient), while garnets from three peridotites are classified as lherzolitic (G9). 52 garnets picked from concentrate have lherzolitic affinities. Lherzolitic diopsides from kimberlite heavy mineral concentrate yield a lithospheric thickness of ~ 200 km. The four garnet peridotite xenoliths and 49 peridotitic garnets from concentrate yield two distinct modes in mantle sampling depths using Ni thermometry, when projected to the Cpx geotherm. A cluster of samples from the higher Ca/Cr lherzolitic garnets equilibrated at 765 to 920 °C with a group of peridotitic garnets (50 % of xenoliths and 28 % of concentrate) from the lower Ca/Cr lherzolitic garnets with anomalously high Ti concentrations yielding super-adiabatic TNi values The aluminum-in-olivine thermometer applied to olivines filtered to be “garnet facies yielded a mantle sampling portion of the mantle cargo from the diamond stability field. A suite of pyroxenitic xenoliths are a feature of each Darby kimberlite target. New screening techniques indicate that these rocks likely originate close to the crust mantle boundary. Osmium isotope analyses of the Darby peridotites reveal whole-rock Re-depletion ages ranging from Mesoarchean to Paleoproterozoic. The pyroxenite xenoliths have very radiogenic Os isotope compositions and provide the first age information from pyroxenites/“eclogites” beneath the Rae craton. Their resulting Archean whole rock TMA ages are consistent with a Mesoarchean age of the western Central Rae lithosphere older than the lithosphere beneath the Repulse Bay block in the East section of the Rae craton (Liu et al., 2016. Precambrian Research 272). The highly depleted olivine compositions, thick cold lithosphere, and Archean ages of the Darby peridotite xenoliths clearly indicate the presence of 200 km thick cold cratonic lithospheric mantle beneath the western segment of the central Rae craton circa 540 Ma. The Archean model ages of most of the pyroxenites support this, notwithstanding the fact that some of these rocks could be sampling either crust or mantle lithologies very close to the crust-mantle boundary. Mantle sampling took place well into the diamond stability field at Darby.
DS201808-1769
2018
Pearson, D.G.Motsamai, T., Harris, J.W., Stachel, T., Pearson, D.G., Armstrong, J.Mineral inclusions in diamonds from Karowe mine, Botswana: super-deep sources for super-sized diamonds?Mineralogy and Petrology, doi.org/10.1007/s00710-018-0604-9 12p.Africa, Botswanadeposit - Karowe

Abstract: Mineral inclusions in diamonds play a critical role in constraining the relationship between diamonds and mantle lithologies. Here we report the first major and trace element study of mineral inclusions in diamonds from the Karowe Mine in north-east Botswana, along the western edge of the Zimbabwe Craton. From a total of 107 diamonds, 134 silicate, 15 oxide, and 22 sulphide inclusions were recovered. The results reveal that 53% of Karowe inclusion-bearing diamonds derived from eclogitic sources, 44% are peridotitic, 2% have a sublithospheric origin, and 1% are websteritic. The dominant eclogitic diamond substrates sampled at Karowe are compositionally heterogeneous, as reflected in wide ranges in the CaO contents (4-16 wt%) of garnets and the Mg# (69-92) and jadeite contents (14-48 mol%) of clinopyroxenes. Calculated bulk rock REEN patterns indicate that both shallow and deep levels of the subducted slab(s) were sampled, including cumulate-like protoliths. Peridotitic garnet compositions largely derive from harzburgite/dunite substrates (~90%), with almost half the garnets having CaO contents <1.8 wt%, consistent with pyroxene-free (dunitic) sources. The highly depleted character of the peridotitic diamond substrates is further documented by the high mean and median Mg# (93.1) of olivine inclusions. One low-Ca garnet records a very high Cr2O3 content (14.7 wt%), implying that highly depleted cratonic lithosphere at the time of diamond formation extended to at least 220 km depth. Inclusion geothermobarometry indicates that the formation of peridotitic diamonds occurred along a 39-40 mW/m2 model geotherm. A sublithospheric inclusion suite is established by three eclogitic garnets containing a majorite component, a feature so far unique within the Orapa cluster. These low- and high-Ca majoritic garnets follow pyroxenitic and eclogitic trends of majoritic substitution, respectively. The origin of the majorite-bearing diamonds is estimated to be between 330 to 420 km depth, straddling the asthenosphere-transition zone boundary. This new observation of superdeep mineral inclusions in Karowe diamonds is consistent with a sublithospheric origin for the exceptionally large diamonds from this mine.
DS201809-2038
2018
Pearson, D.G.Howell, D., Stachel, T., Pearson, D.G., Stern, R.A., Nestola, F., Shirey, S.B., Harris, J.W.Deep carbon through time: the diamond record.Goldschmidt Conference, 1p. AbstractAfrica, Australia, Russia, Canadadeposit - Argyle, De Beers Pool, Jwaneng, Orapa, Udachnaya, Venetia, Wawa, Diavik

Abstract: Earth’s mantle is by far the largest silicate-hosted reservoir of carbon. Diamonds are unrivalled in their ability to record the cycle of mantle carbon and other volatiles over a vast portion of the Earth’s history. They are the product of ascending, cooling, carbon-saturated, metasomatic fluidsmelts and/or redox reactions, predominantly within peridotitic and eclogitic domains in the mantle lithosphere. This paper reports the results of a major secondary ion mass spectrometry (SIMS) carbon isotope study, carried out on 127 diamond samples, spanning a large range of geological time. Detailed transects across the incremental growth zones within each diamond were measured for C isotopes, N abundances and, for samples with N >~200 at.ppm, N isotopes. Given that all of the samples are fragments, recovered when the original crystals were broken to liberate their inclusions, 81 of the analytical traverses have confirmed growth direction context. 98 samples are from studies that have confirmed the dates of the individual diamonds through analysis of their silicate or sulphide inclusions, from source localities including Argyle, De Beers Pool, Jwaneng, Orapa, Udachnaya & Venetia. Additional samples come from Wawa (a minimum age) and Diavik where the samples are tied via inclusion paragenesis to published ages. The peridotitic dataset covers the age range of ~3.3 - 2.0 Ga, with the eclogitic data from 2.9 - 1.0 Ga. In total, 751 carbon isotope and nitrogen concentration measurements have been obtained (425 on peridotitic diamonds, and 326 on eclogitic diamonds) with 470 nitrogen isotope measurements (190 P, 280 E). We attempt to constrain the diamond carbon isotope record through time and its implications for (i) the mantle carbon reservoir, (ii) its oxygen fugacity, (iii) the fluid / melt growth environment of diamonds, (iv) fractionation trends recorded in individual diamonds, and (v) diamond population studies using bulk combustion carbon isotope analysis.
DS201809-2060
2018
Pearson, D.G.Liu, J., Brin, L.E., Pearson, D.G., Bretschneider, L., Luguet, A., van Acken, D., Kjarsgaard, B., Riches, A., Miskovic, A.Diamondiferous Paleoproterozoic mantle roots beneath Arctic Canada: a study of mantle xenoliths from Parry Peninsula and Central Victoria Island.Geochimica et Cosmochimica Acta, doi.org/10.1016/j.gca.2018.08.010 78p.Canada, Nunavut, Parry Peninsula. Central Victoria Islandxenoliths

Abstract: While the mantle roots directly beneath Archean cratons have been relatively well studied because of their economic importance, much less is known about the genesis, age, composition and thickness of the mantle lithosphere beneath the regions that surround the cratons. Despite this knowledge gap, it is fundamentally important to establish the nature of relationships between this circum-cratonic mantle and that beneath the cratons, including the diamond potential of circum-cratonic regions. Here we present mineral and bulk elemental and isotopic compositions for kimberlite-borne mantle xenoliths from the Parry Peninsula and Central Victoria Island, Arctic Canada. These xenoliths provide key windows into the lithospheric mantle underpinning regions to the North and Northwest of the Archean Slave craton, where the presence of cratonic material has been proposed. The mantle xenolith data are supplemented by mineral concentrate data obtained during diamond exploration. The mineral and whole rock chemistry of peridotites from both localities is indistinguishable from that of typical cratonic mantle lithosphere. The cool mantle paleogeotherms defined by mineral thermobarometry reveal that the lithospheric mantle beneath the Parry Peninsula and Central Victoria Island terranes extended well into the diamond stability field at the time of kimberlite eruption, and this is consistent with the recovery of diamonds from both kimberlite fields. Bulk xenolith Se and Te contents, and highly siderophile element (including Os, Ir, Pt, Pd and Re) abundance systematics, plus corresponding depletion ages derived from Re-Os isotope data suggest that the mantle beneath these parts of Arctic Canada formed in the Paleoproterozoic Era, at ?2?Ga, rather than in the Archean. The presence of a diamondiferous Paleoproterozoic mantle root is part of the growing body of global evidence for diamond generation in mantle roots that stabilized well after the Archean. In the context of regional tectonics, we interpret the highly depleted mantle compositions beneath both studied regions as formed by mantle melting associated with hydrous metasomatism in the major Paleoproterozoic Wopmay-Great Bear-Hottah arc systems. These ?2?Ga arc systems were subsequently accreted along the margin of the Slave craton to form a craton-like thick lithosphere with diamond potential thereby demonstrating the importance of subduction accretion in building up Earth’s long-lived continental terranes.
DS201809-2061
2018
Pearson, D.G.Liu, J., Pearson, D.G., Shu, Q., Sigurdsson, H.Hafnium osmium isotope systematics of mantle peridotites from the Cameroon Volcanic Line: implications for dating post-Archean lithospheric mantle.Goldschmidt Conference, 1p. AbstractMantleperidotites

Abstract: The Re-Os isotope system is well suited to constraining the timing of melt depletion of Archean mantle peridotites. In contrast, the variability inherent in post-Archean mantle Os isotope evolution leads to increasing uncertainty in Re-Os model ages. The Lu-Hf isotopic system has shown some potential for dating peridotite formation ages, providing valuable ages that are complementary to the Re-Os system. For post-Archean mantle peridotites, the key target in the Lu-Hf isotopic work is clinopyroxene (Cpx), because of its high Lu and Hf concentrations and the typical absence of garnet in these rocks. However, orthopyroxene (Opx) can contrain 20% or more of the Hf budget of spinel peridotites and somethimes over 40% of the Lu budget, with Lu/Hf ratios 3-4 times those of Cpx. Thus, Opx Lu-Hf isotopic compositions cannot be ignored or simply calculated, as the equilibrium temperatures of mantle peridotites prior to eruption could be lower or higher than the Hf closure temperature (Tc(Hf)~900ºC). Here we explore Lu-Hf partitioning in spinel peridotite xenoliths from the Cameroon Volcanic Line in additin to WR Re-Os analyses. The Hf isotopic composition of Opx in these rocks is equal to or higher than that of Cpx, consistent with some samples having equilibrium temperatures close to Tc(Hf). Combining Cpx and Opx, the constructed WR Lu-Hf isochron yields an age of 2.01±0.36 Ga (2?; MSWD = 11.4; ?Hfi = -0.8±19.2), which is in accordance with the oldest of the variable Re-Os model ages. The continental sector of the Cameroon Line runs close to the edge of the Congo craton. The Hf-Os data indicate that the lithosphere underpinning this region formed in the Paleoproterozoic (~2Ga) most likely during the Paleoproterzoic assembly between the Congo and West African Cratons. We emphasize that Opx and Cpx should be combined together to construct the WR isochron in order to obtain the precise age and initial Hf isotope compositions of post-Archean spinel peridotites.
DS201809-2062
2018
Pearson, D.G.Liu, J., Pearson, D.G., Bretschneider, L., Luguet, A., Van Acken, D., Kjarsgaard, B., Riches, A., Miskovic, A.Diamondiferous Proterozoic mantle roots beneath Arctic Canada.Goldschmidt Conference, 1p. AbstractCanada, Parry Peninsula, Victoria Islandxenoliths

Abstract: The mantle roots directly beneath Archean cratons have been relatively well studied because of their economic importance, yet much less is known about the genesis, age, composition and thickness of the mantle lithosphere beneath the regions surrounding these cratons. However, it is critically important to establish the nature of the relationship between this circum-cratonic mantle and that beneath the cratons, including the diamond potential of circum-cratonic regions. Here we present mineral and bulk elemental and isotopic compositions for kimberlite-borne mantle xenoliths from the Parry Peninsula (PP) and Central Victoria Island (CVI), Arctic Canada. These xenoliths provide key windows into the lithospheric mantle underpinning regions to the North and Northwest of the Slave craton, where the presence of cratonic mantle has been proposed. The mineral and whole rock chemistry of peridotites from both localities is indistinguishable from that of typical cratonic mantle lithosphere. The cool mantle geotherms defined by mineral thermobarometry reveal that the lithospheric mantle beneath the PP and CVI terranes extended well into the diamond stability field at the time of kimberlite eruption, consistent with the recovery of diamonds from both kimberlite fields. Bulk Se, Te, and highly siderophile element abundance systematics, plus Re-Os isotope age data suggest that the mantle beneath these parts of Arctic Canada formed at ~2 Ga, rather than in the Archean. The presence of a diamondiferous Paleoproterozoic mantle root is part of the growing body of evidence for peridotitic diamond generation in mantle roots that stabilized well after the Archean. In the context of regional tectonics, the highly depleted mantle compositions beneath both regions developed during mantle melting associated with hydrous metasomatism in the major Paleoproterozoic Wopmay- Great Bear-Hottah arc systems. These terranes were subsequently accreted along the margin of the Slave craton to form a craton-like thick lithosphere with significant diamond potential.
DS201809-2079
2018
Pearson, D.G.Regier, M.E., Pearson, D.G., Stachel, T., Stern, R.A., Harris, J.W.Oxygen isotopes in Kankan super deep diamond inclusions reveal variable slab mantle interaction.Goldschmidt Conference, 1p. AbstractAfrica, South Africa, Guinea, South America, Brazildeposit - Kankan, Jagersfontein, Juina

Abstract: Inclusions in super-deep diamonds provide a unique window to the sublithospheric mantle (e.g. [1-4]). Here we present oxygen isotopes for Kankan majoritic garnet and former bridgmanite inclusions. The clustering of Kankan majorites around a ?18O of +9‰ is nearly identical to those reported from Jagersfontein [1]. This elevated and nearly constant ?18O signal indicates homogenization of partial melts from the uppermost part of altered basaltic slabs. Conversely, ?18O values in Juina majorites are highly variable [2] due to crystallization from small, discrete melt pockets in a heterogeneous eclogitic source. While all these majorites have eclogitic/pyroxenitic Cr2O3 and CaO contents, charge-balance for Si[VI] is achieved very differently, with Jagersfontein [3], Kankan [4], and Juina [2] majorites transitioning from eclogitic Na[VIII]Si[VI] to peridotitic-pyroxenitic [5] Mg[VI]Si[VI] substitutions. We interpret this shift as the result of homogenized eclogitic partial melts infiltrating and reacting with adjacent pyrolitic mantle at Kankan and Jagersfontein. Increases in Mg# and Cr2O3 with reductions in ?18O support this reaction. This model is in agreement with recent experiments in which majorites and diamonds form from a reaction of slab-derived carbonatite with reduced pyrolite at 300-700 km depth [6]. The Kankan diamonds also provide an opportunity to establish the chemical environment of the lower mantle. Four inclusions of MgSiO3, inferred to be former bridgmanite [4], provide the first-measured ?18O values for lower mantle samples. These values suggest derivation from primitive mantle, or unaltered subducted oceanic lithospheric mantle. The Kankan super-deep inclusions thus provide a cross-section of deep mantle that highlights slab-pyrolite reactions in the asthenosphere and primitive compositions in the lower mantle.
DS201809-2082
2018
Pearson, D.G.Sarkar, C., Kjarsgaard, B.A., Pearson, D.G., Heaman, L.M., Locock, A.J., Armstrong, J.P.Geochronology, classification and mantle source characteristics of kimberlites and related rocks from the Rae craton, Melville Peninsula, Nunavut, Canada.Mineralogy and Petrology, doi.org/10.1007/ s00710-018-0632-5 20p.Canada, Nunavut, Melville Peninsuladeposit - Pelly Bay, Darby, Aviat, Qilalugaq

Abstract: Detailed geochronology along with petrographic, mineralogical and geochemical studies have been conducted on recently found diamond-bearing kimberlitic and related rocks in the Rae Craton at Aviat and Qilalugaq, Melville Peninsula, north-east Canada. Magmatic rocks from the Aviat pipes have geochemical (both bulk rock and isotopic) and mineralogical signatures (e.g., core to rim Al and Ba enrichment in phlogopite) similar to Group I kimberlite. In contrast, Aviat intrusive sheets are similar to ‘micaceous’ Group II kimberlite (orangeite) in their geochemical and mineralogical characteristics (e.g., phlogopite and spinel compositions, highly enriched Sr isotopic signature). Qilalugaq rocks with the least crustal contamination have geochemical and mineralogical signatures [e.g., high SiO2, Al2O3 and H2O; low TiO2 and CO2; less fractionated REE (rare earth elements), presence of primary clinopyroxene, phlogopite and spinel compositions] that are similar to features displayed by olivine lamproites from Argyle, Ellendale and West Greenland. The Naujaat dykes, in the vicinity of Qilalugaq, are highly altered due to extensive silicification and carbonation. However, their bulk rock geochemical signature and phlogopite chemistry are similar to Group I kimberlite. U-Pb perovskite geochronology reveals that Aviat pipes and all rocks from Qilalugaq have an early Cambrian emplacement age (540-530 Ma), with the Aviat sheets being ~30 Ma younger. This volatile-rich potassic ultramafic magmatism probably formed by varying degrees of involvement of asthenospheric and lithospherically derived melts. The spectrum of ages and compositions are similar to equivalent magmatic rocks observed from the nearby north-eastern North America and Western Greenland. The ultimate trigger for this magmatism could be linked to Neoproterozoic continental rifting during the opening of the Iapetus Ocean and breakup of the Rodinia supercontinent.
DS201810-2326
2018
Pearson, D.G.Guotana, J.M., Morishita, T., Yamaguchi, R., Nishio, I., Tamura, A., Tani, K., Harigane, Y., Szilas, K., Pearson, D.G.Contrasting textural and chemical signatures of chromitites in the Mesoarchean Ulamertoq peridotite body, southern West Greenland.MDPI Geosciences, Researchgate 19p.Europe, Greenlandperidotite

Abstract: Peridotites occur as lensoid bodies within the Mesoarchaean orthogneiss in the Akia terrane of Southern West Greenland. The Ulamertoq peridotite body is the largest of these peridotites hosted within the regional orthogneiss. It consists mainly of olivine, orthopyroxene, and amphibole-rich ultramafic rocks exhibiting metamorphic textural and chemical features. Chromitite layers from different localities in Ulamertoq show contrasting characteristics. In one locality, zoned chromites are hosted in orthopyroxene-amphibole peridotites. Compositional zonation in chromites is evident with decreasing Cr and Fe content from core to rim, while Al and Mg increase. Homogeneous chromites from another locality are fairly uniform and Fe-rich. The mineral chemistry of the major and accessory phases shows metamorphic signatures. Inferred temperature conditions suggest that the zoned chromites, homogeneous chromites, and their hosts are equilibrated at different metamorphic conditions. In this paper, various mechanisms during the cumulus to subsolidus stages are explored in order to understand the origin of the two contrasting types of chromites.
DS201810-2370
2018
Pearson, D.G.Ranger, I.M., Heaman, L.M., Pearson, D.G., Muntener, C., Zhuk, V.Punctuated, long lived emplacement history of the Renard 2 kimberlite, Canada, revealed by new high precision U-Pb groundmass perovskite dating. IF-TIMSMineralogy and Petrology, doi.org/101007/ s00710-018-0629-0 13p.Canada, Quebecdeposit - Renard

Abstract: Kimberlites are rare volatile-rich ultramafic magmas thought to erupt in short periods of time (<1 Myr) but there is a growing body of evidence that the emplacement history of a kimberlite can be significantly more protracted. In this study we report a detailed geochronology investigation of a single kimberlite pipe from the Renard cluster in north-central Québec. Ten new high precision ID-TIMS (isotope dilution - thermal ionization mass spectrometry) U-Pb groundmass perovskite dates from the main pipe-infilling kimberlites and several small hypabyssal kimberlites from the Renard 2 pipe indicate kimberlite magmatism lasted at least ~20 Myr. Two samples of the main pipe-infilling kimberlites yield identical weighted mean 206Pb/238U perovskite dates with a composite date of 643.8?±?1.0 Myr, interpreted to be the best estimate for main pipe emplacement. In contrast, six hypabyssal kimberlite samples yielded a range of weighted mean 206Pb/238U perovskite dates between ~652-632 Myr. Multiple dates determined from these early-, syn- and late-stage small hypabyssal kimberlites in the Renard 2 pipe demonstrate this rock type (commonly used to date kimberlites) help to constrain the duration of kimberlite intrusion history within a pipe but do not necessarily reliably record the emplacement age of the main diatreme in the Renard cluster. Our results provide the first robust geochronological data on a single kimberlite that confirms the field relationships initially observed by Wagner (1914) and Clement (1982); the presence of antecedent (diatreme precursor) intrusions, contemporaneous (syn-diatreme) intrusions, and consequent (post-diatreme) cross-cutting intrusions. The results of this detailed U-Pb geochronology study indicate a single kimberlite pipe can record millions of years of magmatism, much longer than previously thought from the classical viewpoint of a rapid and short-duration emplacement history.
DS201812-2773
2018
Pearson, D.G.Ali, H., Regier, M.E., Pearson, D.G.Increased recovery of diamonds from eclogite by electrical pulse disaggregation. SELFRAG2018 Yellowknife Geoscience Forum , p. 91-92. abstractAfrica, South Africadeposit - Roberts Victor

Abstract: It is well known that mechanical disaggregation, such as jaw crushing, can cause irreversible damage to valuable gemstones hosted in crystalline rocks. The SELFRAG Lab device uses electrical pulses at high voltages - typically between 150 and 200 kV - to separate material into individual grains along natural boundaries. The purpose of this research is to assess the viability of the SELFRAG as a tool to disaggregate diamond-bearing eclogites, and to assess if this method preserves grains that would otherwise be damaged through mechanical disaggregation. In order to test the applicability of the SELFRAG to diamond recovery from mechanically strong diamond-bearing lithologies, we studied its effects on a diamondiferous eclogite, RV09, from Roberts Victor mine. The Roberts Victor mine is located in South Africa and is renowned for its unusually high abundance of mantle-derived eclogite xenoliths1. Before the eclogite was disaggregated, we bisected the sample and used a CT scan to determine its constituent minerals and the spatial distribution of diamond. One half of the sample was then placed into the SELFRAG, where it was subjected to ~100 shots of 200 kV electrical discharges that segregated the sample into individual grains of similar sizes. The other half was jaw crushed, using a steel jaw crusher which produced non-uniform composite grains and abundant fine material. The varying sizes and aggregate pieces made it difficult to pick diamonds, and after no diamonds were found, the jaw-crushed portion underwent further disaggregation in the SELFRAG. After exerting the same time and effort picking through both portions of the RV09 sample, ten diamonds were recovered from the electronically disaggregated portion, while no diamonds were found in the conventionally disaggregated sample. The diamonds released from the SELFRAG were then imaged with a scanning electron microscope (SEM) to determine the extent to which the diamonds were damaged. Most of the released diamonds showed no evidence of breakage, but a few showed signs of damage that may have occurred prior to kimberlite eruption. The dramatic disparity between the number of diamonds recovered with the SELFRAG and the lack of diamonds in the jaw crushed portion indicates that electrical disaggregation is a superior method compared to the conventional mechanical comminution technique. There are little to no signs of breakage in the SELFRAG-liberated diamonds, whereas, the damage caused by jaw crushing was extensive enough to produce small fragments not readily visible via optical microscopy. The SELFRAG is a promising alternative to conventional disaggregation and offers a practical solution for lessening damage to valuable stones in rocks such as eclogites and kimberlites.
DS201812-2784
2018
Pearson, D.G.Bulanova, G.P., Smith, C.B., Pearson, D.G., Kohn, S.C., Davy, A.T., McKay, A., Marks, A.Murowa deposit: Diamonds from the Murowa kimberlites: formation within extremely depleted and metasomatized Zimbabwean peridotitic subcontinental mantle.Society of Economic Geology Geoscience and Exploration of the Argyle, Bunder, Diavik, and Murowa Diamond Deposits, Special Publication no. 20, pp. 425-Africa, Zimbabwedeposit - Murowa
DS201812-2813
2018
Pearson, D.G.Gruber, B.H., Chacko, T., Pearson, D.G.The thermochemical conditions of the Diavik lower crust: a kimberlite-hosted xenolith study.2018 Yellowknife Geoscience Forum , p. 25-26. abstractCanada, Northwest Territoriesdeposit - Diavik

Abstract: Thermochemical variables such as lower crustal heat production and Moho temperatures in cratonic regions offer critical insight in constraining the thermal and geodynamic evolution of the lithosphere. In this study, 15 lower crustal granulite xenoliths erupted via the A154N kimberlite at the Diavik mine in the NWT, Canada were studied to quantify the thermal properties of the local Moho and the effects of different heat production models on geotherm models. We quantitatively constrain the thermal properties of the local Moho and the effects of different heat production models on ancient Moho temperatures, the effects of crustal thickness on Moho temperatures, and potential lower crustal compositions. We evaluate the effect of these parameters on total lithospheric thickness estimates. In order to test the accuracy of deep crust thermal calculations, we estimated the ambient temperature of the lower crust at the time of kimberlite eruption through garnet-biotite Fe-Mg exchange geothermometry (Ferry & Spear, 1978). Rim compositions from touching garnet-biotite pairs were used in the calculations and yielded temperatures of 524 ± 77°C (n=20). These represent a maximum estimate of the ambient lower crustal temperature as the closure temperature of garnet-biotite Fe-Mg exchange between garnet and biotite may be higher than the ambient temperature. The primary objective of this study is to quantify lower crustal heat production and its effects on the thermal architecture of cratons. The concentrations of the main heat-producing elements (HPEs) U, Th, and K were quantified via LA-ICP-MS and EPMA in multiple mineral phases per xenolith. By combining these measurements with mineral modes, we derived reconstructed bulk-rock HPE concentrations that were utilized to calculate a range of lower crustal heat production values. This method is preferred over whole-rock analyses as 1) kimberlite is generally enriched in HPEs (Tappe et al. 2013) and can bias trace-element data for their xenoliths and 2) data on individual minerals allows for theoretical lower crustal compositions to be calculated on an idealized basis. A lower crust comprising exclusively mafic granulite (garnet, plagioclase, clinopyroxene ± orthopyroxene) provides a lower bound to heat production (0.07 ± 0.04 W/m3) whereas a lower crust made exclusively of high-grade metasedimentary rocks yields an upper bound (0.42 ± 0.08 W/m3). Both endmembers are present as xenoliths in the A154N kimberlite but mafic granulites predominate following the worldwide trend (Rudnick, 1992). We model the lower crust comprising 20% metasedimentary granulites and 80 % depleted mafic granulites, in accordance with the present xenolith collection. Using this preferred crustal model, we calculate an average heat production of 0.12 ± 0.05 W/m3) for the lower crust beneath Lac de Gras. Utilizing heat flow measurements (Russell et thickness estimates (Mareschal et al. 2004) in conjunction with these HPE determinations, the Moho temperature underlying A-154N can be calculated to be 502 ± 10°C. Using these values along with available mantle xenolith thermobaromtetry (Hasterok & Chapman, 2011) the geotherm is extrapolated to present a mantle potential temperature of 1365°C, at 200 km (FITPLOT, Mather et al, 2011).
DS201812-2822
2018
Pearson, D.G.Jaques, A.L., Luguet, A., Smith, C.B., Pearson, D.G., Yaxley, G.M., Kobussen, A.F.Argyle deposit: Nature of the mantle beneath the Argyle AK1 lamproite pipe: constraints from mantle xenoliths, diamonds, and lamproite geochemistry.Society of Economic Geology Geoscience and Exploration of the Argyle, Bunder, Diavik, and Murowa Diamond Deposits, Special Publication no. 20, pp. 119-144.Australia, western Australiadeposit - Argyle
DS201812-2831
2018
Pearson, D.G.Krebs, M.Y., Pearson, D.G., Stachel, T., Laiginhas, F., Woodland, S., Chinn, I., Kong, J.A common parentage - Low abundance trace element data of gem diamonds reveals similar fluids to fibrous diamonds. ( silicate/sulphide)Lithos, doi.org/10.1016/ jlithos.2018.11.025 49p.Canada, Ontario, Attawapiskat, Africa, South Africadeposit - Victor, Finsch, Newlands

Abstract: Quantitative trace element data from high-purity gem diamonds from the Victor Mine, Ontario, Canada as well as near-gem diamonds from peridotite and eclogite xenoliths from the Finsch and Newlands mines, South Africa, acquired using an off-line laser ablation method show that we see the same spectrum of fluids in both high-purity gem and near-gem diamonds that was previously documented in fibrous diamonds. “Planed” and “ribbed” trace element patterns characterize not only the high-density fluid (HDF) inclusions in fibrous diamonds but also in gem diamonds. Two diamonds from two Finsch harzburgite xenoliths show trace element patterns similar to those of saline fluids, documenting the involvement of saline fluids in the precipitation of gem diamonds, further strengthening the link between the parental fluids of both gem and fibrous diamonds. Differences in trace element characteristics are evident between Victor diamonds containing silicate inclusions compared with Victor diamonds containing sulphide inclusions. The sulphide-bearing diamonds show lower levels of inter-element fractionation and more widely varying siderophile element concentrations - indicating that the silicate and sulphide-bearing diamonds likely formed by gradations of the same processes, via melt-rock reaction or from a subtly different fluid source. The shallow negative LREEN-HREEN slopes displayed by the Victor diamonds establish a signature indicative of original derivation of the diamond forming agent during major melting (~10% melt). Consequently, this signature must have been passed on to HDFs separating from such silicate melts.
DS201812-2860
2018
Pearson, D.G.Pearson, D.G., Liu, J., Smith, C.B., Mather, K.A., Krebs, M.Y., Bulanova, G.P., Kobussen, A.F.Murowa deposit: Characteristics and origin of the mantle root beneath the Murowa diamond mine: implications for craton and diamond formation.Society of Economic Geology Geoscience and Exploration of the Argyle, Bunder, Diavik, and Murowa Diamond Deposits, Special Publication no. 20, pp. 403-424.Africa, Zimbabwedeposit - Murowa
DS201812-2867
2018
Pearson, D.G.Poitras, S.P., Pearson, D.G., Hardman, M.F., Stachel, T., Nowell, G.M.Evidence for a 200 km thick diamond bearing root beneath the Central Mackenzie Valley, Northwest Territories, Canada? Diamond indicator mineral geochemistry from the Horn Plateau and Trout Lake regions.Mineralogy and Petrology, doi.org/10.1007/ s00710-018-0641-4 18p.Canada, Northwest Territoriesindicator minerals, geocthermobarometry

Abstract: The Central Mackenzie Valley (CMV) area of Northwest Territories is underlain by Precambrian basement belonging to the North American Craton. The potential of this area to host kimberlitic diamond deposits is relatively high judging from the seismologically-defined lithospheric thickness, age of basement rocks (2.2-1.7 Ga) and presence of kimberlite indicator minerals (KIMs) in Quaternary sediments. This study presents data for a large collection of KIMs recovered from stream sediments and till samples from two study areas in the CMV, the Horn Plateau and Trout Lake. In the processed samples, peridotitic garnets dominate the KIM grain count for both regions (> 25% each) while eclogitic garnet is almost absent in both regions (< 1% each). KIM chemistry for the Horn Plateau indicates significant diamond potential, with a strong similarity to KIM systematics from the Central and Western Slave Craton. The most significant issue to resolve in assessing the local diamond potential is the degree to which KIM chemistry reflects local and/or distal kimberlite bodies. Radiogenic isotope analysis of detrital kimberlite-related CMV ilmenite and rutile grains requires at least two broad age groups for eroded source kimberlites. Statistical analysis of the data suggests that it is probable that some of these KIMs were derived from primary and/or secondary sources within the CMV area, while others may have been transported to the area from the east-northeast by Pleistocene glacial and/or glaciofluvial systems. At this stage, KIM chemistry does not allow the exact location of the kimberlitic source(s) to be constrained.
DS201812-2870
2018
Pearson, D.G.Regier, M.E., Pearson, D.G., Stachel, T., Stern, R.A., Harris, J.Tracing the formation and abundance of superdeep diamonds.2018 Yellowknife Geoscience Forum , p. 63. abstractAfrica, Guineadeposit - Kankan

Abstract: Super-deep diamonds from the transition zone and lower mantle are valuable targets for mining, as they are often large, gem-quality1 or ultra-valuable type IIb stones2. Hence, in mine prospects, it may become important to determine the various populations of sub-lithospheric diamonds. Unambiguously identifying a diamond’s depth of formation is difficult as some minerals can be indicative of various depth regimes (e.g., ferropericlase, Ca-walstromite, enstatite, clinopyroxene, coesite). Here, we use the oxygen isotope compositions of inclusions in Kankan diamonds from Guinea to distinguish between the various diamond-forming processes that happen at lithospheric, asthenospheric to transition zone, and lower mantle depths. In this way, we hope to establish a process by which isotope geochemistry can better constrain the populations of superdeep diamonds in kimberlites, and can assist in estimating a pipe’s propensity for large, valuable stones. Oxygen isotopic analysis by secondary ion mass spectrometry (SIMS) is a high-precision technique that can track hydrothermal alteration that occurred at or close below the ocean floor. Our analyses of inclusions from Kankan diamonds demonstrate that garnets with 3-3.03 Si cations (pfu) have ?18O that are well-constrained within the normal values expected for peridotitic and eclogitic inclusions, but that garnets with ?3.04 Si cations (pfu) have consistently high ?18O (median: 10‰) that slightly decreases with increasing Cr2O3. We interpret this signal as the reaction between a melted carbonate-rich oceanic slab and normal convecting asthenosphere3. In contrast, retrogressed, or former, bridgmanite has ?18O values similar to primitive mantle, suggesting little involvement of slab melts. In contrast to the worldwide suite of lithospheric inclusions of eclogitic paragenesis (median ?18O of 7.03‰)4,5, diamonds derived from ~250 to 500 km have inclusions with consistent, extremely high oxygen isotopes (median: 9.32‰)6,7, due to the melting of extremely enriched carbonated oceanic crust. Diamonds from the lower mantle, however, have inclusions with primitive mantle oxygen isotopes, suggesting a different formation process. The clear distinction in inclusion ?18O between lithospheric, asthenospheric to transition zone, and lower mantle diamond populations is useful in informing the depth regime of a suite of stones, especially those with inclusions of ambiguous depths (e.g., clinopyroxene, coesite, Ca-walstromite, enstatite, ferropericlase, etc.). For instance, we are currently searching for exotic oxygen isotopes in ferropericlase that indicate asthenospheric diamond growth, rather than the primitive mantle values expected for lower mantle ferropericlase. In conclusion, oxygen isotopic analyses of diamond inclusions can identify various sublithsopheric diamond populations, and may benefit the assessment of a mine’s potential for large gem-quality, or type IIb diamonds.
DS201812-2884
2018
Pearson, D.G.Siva-Jothy, W., Chinn, I., Stachel, T., Pearson, D.G.Resorption features of macro and micro diamonds from Gahcho Kue.2018 Yellowknife Geoscience Forum , p. 120. abstractCanada, Northwest Territoriesdeposit - Gahcho Kue

Abstract: Studies into the relationship between oxygen fugacity of mantle fluids/melts and etch features on diamond surfaces have shown specific fluid/melt compositions correspond to associated etch features. A classification scheme has been proposed to determine the fluid composition within a kimberlite by examining etch features associated with diamond surfaces as a proxy for fluid composition in an ascending diamondiferous kimberlite. A suite of 388 microdiamonds (defined as diamonds which pass through a 0.5 mm square mesh screen) and 88 macrodiamonds taken from various drill hole depths in the Hearne kimberlite and 88 inclusion-bearing macrodiamonds from the Gahcho Kué mine (NWT) were viewed under a secondary electron microscope for their surface features in accordance with this scheme. Two hundred and thirty specimens show shallow-depth etch features that can be easily classified: the main features observed were trigons and truncated trigons on the {111} faces and/or tetragons on the {100} faces (indicating etching by fluids of variable CO2:H2O ratios). Thirty-four specimens show deeper etched features that represent either extreme degrees of regular etching (such as deeply-etched tetragons), or corrosion type etching, wherein the diamond lattice is etched in a fluid-free melt. Variability between crystal habits exists between the size fractions studied, with cubic habits only being observed in the microdiamond population. This implies variable formation conditions for the two different diamond size fractions studied from Gahcho Kué. Among microdiamonds, surface textures associated with fluid-related etching are markedly more variable, with truncated trigons, tetragons, and both positive and negative trigons being observed. However, these often occur in combination with features showing a large variability in their depth to size ratio between samples, which is typically caused by mantle-related etching. These observations suggest repeated interaction of fluids/melts with the Gahcho Kué diamond population, with at least some of the fluids affecting the microdiamonds being more CO2-rich than those that etched the macrodiamond fraction.
DS201901-0054
2018
Pearson, D.G.Pearson, D.G.Modern advances in the understanding of diamond formation. KeynoteGems & Gemology, Sixth International Gemological Symposium Vol. 54, 3, 1p. Abstract p. 270.Globaldiamond genesis

Abstract: For the past 50 years, the majority of diamond research has focused on diamonds derived from the lithospheric mantle root underpinning ancient continents. While lithospheric diamonds are currently thought to form the mainstay of the world’s economic production, the continental mantle lithosphere reservoir comprises only ~2.5% of the total volume of Earth. Earth’s upper mantle and transition zone, extending from beneath the lithosphere to a depth of 670 km, occupy a volume approximately 10 times larger. Diamonds from these deeper parts of the earth—“superdeep diamonds”—are more abundant than previously thought. They appear to dominate the high-value large diamond population that comes to market. Recent measurements of the carbon and nitrogen isotope composition of superdeep diamonds from Brazil and southern Africa, using in situ ion probe techniques, show that they document the deep recycling of volatile elements (C, N, O) from the surface of the earth to great depths, at least as deep as the uppermost lower mantle. The recycled crust signatures in these superdeep diamonds suggest their formation in regions of subducting oceanic plates, either in the convecting upper mantle or the transition zone plus lower mantle. It is likely that the deep subduction processes involved in forming these diamonds also transport surficial hydrogen into the deep mantle. This notion is supported by the observation of a high-pressure olivine polymorph—ringwoodite—with close to saturation levels of water. Hence, superdeep dia­monds document a newly recognized, voluminous “diamond factory” in the deep earth, likely producing diamonds right up to the present day. Such diamonds also provide uniquely powerful views of how crustal material is recycled into the deep earth to replenish the mantle’s inventory of volatile elements. The increasing recognition of superdeep diamonds in terms of their contribution to the diamond economy opens new horizons in diamond exploration. Models are heavily influenced by the search for diamonds associated with highly depleted peridotite (dunites and harzburgites). Such harzburgitic diamonds were formed in the Archean eon (>2.5 Ga) within lithospheric mantle of similar age. It is currently unclear what the association is between these ancient lithospheric diamonds and large, high-value diamonds, but it is likely a weak one. In contrast, the strong association between superdeep diamonds and these larger stones opens up a new paradigm because the available age constraints for superdeep diamonds indicate that they are much younger than the ancient lithospheric diamonds. Their younger age means that superdeep diamonds may be formed in non-Archean mantle, or mantle that has been strongly overprinted by post-Archean events that would otherwise be deemed unfavorable for the preservation of ancient lithospheric diamonds. An additional factor in the search for new diamond deposits is the increasing recognition that major diamond deposits can form in lithospheric mantle that is younger than—or experienced major thermal disruption since—the canonical 2.5 billion years usually thought to be most favorable for diamond production. This talk will explore these new dimensions in terms of the potential for discovering new diamond sources in “unconventional” settings.
DS201901-0076
2018
Pearson, D.G.Shirey, S.B., Pearson, D.G.How to obtain and interpret diamond ages.Gems & Gemology, Sixth International Gemological Symposium Vol. 54, 3, 1p. Abstract p. 272-3.Africa, Sierra Leonegeochronology

Abstract: Diamond ages are obtained from radiogenic isotopic analysis (Rb-Sr, Sm-Nd, Re-Os, and Ar-Ar) of mineral inclusions (garnet, pyroxene, and sulfide). As diamonds are xenocrysts that cannot be dated directly, the ages obtained on mineral inclusions provide a unique set of interpretive challenges to assure accuracy and account for preexisting history. A primary source of geological/mineralogical uncertainty on diamond ages is any process affecting protogenetic mineral inclusions before encapsulation in the diamond, especially if it occurred long before diamond formation. In practical application, the isotopic systems discussed above also carry with them inherent systemic uncertainties. Isotopic equilibrium is the essential condition required for the generation of a statistically robust isochron. Thus, isochron ages from multiple diamonds will record a valid and accurate age when the diamond-forming fluid promotes a large degree of isotopic equilibrium across grain scales, even for preexisting (“protogenetic”) minerals. This clearly can and does occur. Furthermore, it can be analytically tested for, and has multiple analogues in the field of dating metamorphic rocks. In cases where an age might be suspect, an age will be valid if its regression uncertainties can encompass a known and plausible geological event (especially one for which an association exists between that event and the source of diamond-forming fluids) and petrogenetic links can be established between inclusions on the isochron. Diamonds can be dated in six basic ways: 1. model ages 2. radiogenic daughter Os ages (common-Os-free) 3. single-diamond mineral isochrons 4. core to rim ages 5. multiple single-diamond isochron/array ages 6. composite isochron/array ages Model ages (1) are produced by the intersection between the evolution line for the inclusion and a reference reservoir such as the mantle. The most accurate single-diamond age is determined on a diamond with multiple inclusions (3). In this case an internal isochron can be obtained that not only establishes equilibrium among the multiple grains but also unequivocally dates the time of diamond growth. With extreme luck in obtaining the right diamond, concentric diamond growth zones visible in UV fluorescence or cathodoluminescence can sometimes be shown to constrain inclusions to occur in the core of the diamond and in the exterior at the rim. These single grains can be extracted to give a minimum growth time (4) for the diamond. In optimal situations, multiple inclusions are present within single growth zones, in single diamonds, allowing internal isochrons to be constructed for individual growth zones in single diamonds. If enough diamonds with inclusions can be obtained for study, valid ages for diamond populations can be obtained on multiple single-diamond ages that agree (5) or on composited, mineralogically similar inclusions to give an average age (6).
DS201901-0085
2018
Pearson, D.G.Wang, H., van Hunen, J., Pearson, D.G.Making Archean cratonic roots by lateral compression: a two stage thickening and stabilization model.Tectonophysics, Vol. 746, pp. 562-571.Mantlemelting

Abstract: Archean tectonics was capable of producing virtually indestructible cratonic mantle lithosphere, but the dominant mechanism of this process remains a topic of considerable discussion. Recent geophysical and petrological studies have refuelled the debate by suggesting that thickening and associated vertical movement of the cratonic mantle lithosphere after its formation are essential ingredients of the cratonization process. Here we present a geodynamical study that focuses on how the thick stable cratonic lithospheric roots can be made in a thermally evolving mantle. Our numerical experiments explore the viability of a cratonization process in which depleted mantle lithosphere grows via lateral compression into a > 200-km thick, stable cratonic root and on what timescales this may happen. Successful scenarios for craton formation, within the bounds of our models, are found to be composed of two stages: an initial phase of tectonic shortening and a later phase of gravitational self-thickening. The initial tectonic shortening of previously depleted mantle material is essential to initiate the cratonization process, while the subsequent gravitational self-thickening contributes to a second thickening phase that is comparable in magnitude to the initial tectonic phase. Our results show that a combination of intrinsic compositional buoyancy of the cratonic root, rapid cooling of the root after shortening, and the long-term secular cooling of the mantle prevents a Rayleigh-Taylor type collapse, and will stabilize the thick cratonic root for future preservation. This two-stage thickening model provides a geodynamically viable cratonization scenario that is consistent with petrological and geophysical constraints.
DS201902-0288
2019
Pearson, D.G.Krebs, M.Y., Pearson, D.G., Stachel, T., Laiginhas, F., Woodland, S., Chinn, I., Kong, J.A common parentage low abundance trace element data of gem diamonds reveals similar fluids to fibrous diamonds.Lithos, Vol. 324, 1, pp. 356-370.Canada, Ontario, Africa, South Africadeposit - Victor, Finsch, Newlands

Abstract: Quantitative trace element data from high-purity gem diamonds from the Victor Mine, Ontario, Canada as well as near-gem diamonds from peridotite and eclogite xenoliths from the Finsch and Newlands mines, South Africa, acquired using an off-line laser ablation method show that we see the same spectrum of fluids in both high-purity gem and near-gem diamonds that was previously documented in fibrous diamonds. "Planed" and "ribbed" trace element patterns characterize not only the high-density fluid (HDF) inclusions in fibrous diamonds but also in gem diamonds. Two diamonds from two Finsch harzburgite xenoliths show trace element patterns similar to those of saline fluids, documenting the involvement of saline fluids in the precipitation of gem diamonds, further strengthening the link between the parental fluids of both gem and fibrous diamonds. Differences in trace element characteristics are evident between Victor diamonds containing silicate inclusions compared with Victor diamonds containing sulphide inclusions. The sulphide-bearing diamonds show lower levels of inter-element fractionation and more widely varying siderophile element concentrations - indicating that the silicate and sulphide-bearing diamonds likely formed by gradations of the same processes, via melt-rock reaction or from a subtly different fluid source. The shallow negative LREEN-HREEN slopes displayed by the Victor diamonds establish a signature indicative of original derivation of the diamond forming agent during major melting (~10% melt). Consequently, this signature must have been passed on to HDFs separating from such silicate melts.
DS201902-0310
2018
Pearson, D.G.Regier, M.E., Miskovic, A., Ickert, R.B., Pearson, D.G., Stachel, T., Stern, R.A., Kopylova, M.An oxygen isotope test for the origin of Archean mantle rootsGeochemical Perspectives Letters, Vol. 9, pp. 6-10. 10.7185/geochemlet.1830Mantleperidotites

Abstract: The origin of the peridotites that form cratonic mantle roots is a central issue in understanding the history and survival of Earth’s oldest continents. A long-standing hypothesis holds that the unusual bulk compositions of some cratonic peridotites stem from their origin as subducted oceanic serpentinite, dehydrated during subduction to form rigid buoyant keels (Schulze, 1986; Canil and Lee, 2009). We present oxygen isotope data from 93 mantle peridotites from five different Archean cratons to evaluate their possible origin as serpentinites. Cratonic mantle peridotite shows remarkably uniform ?18O values, identical to modern MORB-source mantle, that do not vary with bulk rock Si-enrichment or Ca-depletion. These data clearly conflict with any model for cratonic lithosphere that invokes serpentinite as a protolith for cratonic peridotite, and place additional constraints on cratonic mantle origins. We posit that the uniform ?18O was produced by sub-arc and/or MOR depletion processes and that the Si-enriched nature of some samples is unlikely to be related to slab melt infiltration. Instead, we suggest a peridotitic source of Si-enrichment, derived from ascending mantle melts, or a water-fluxed depleted mantle. These variably Si-enriched, cratonic mantle protoliths were then collisionally compressed into the thick cratonic roots that have protected Earth’s oldest continental crust for over 2.5 Gyr.
DS201902-0319
2019
Pearson, D.G.Scott, J.M., Liu, J., Pearson, D.G., Harris, G.A., Czertowicz, T.A., Woodland, S.J., Riches, A.J.V., Luth, R.W.Continent stabilization by lateral accretion of subduction zone-processed depleted mantle residues: insights from Zealandia.Earth and Planetary Science Letters, Vol. 507, pp. 175-186.Mantleperidotite

Abstract: To examine how the mantle lithosphere stabilises continents, we present a synthesis of the mantle beneath Zealandia in the SW Pacific Ocean. Zealandia, Earth's “8th continent”, occurs over 4.9 M km2 and comprises a fore-arc, arc and back-arc fragment rifted from the Australia-Antarctica Gondwana margin 85 Myr ago. The oldest extant crust is ?500 Ma and the majority is Permian-Jurassic. Peridotitic rocks from most known locations reveal the underpinning mantle to comprise regional domains varying from refractory (Al2O3 < 1 wt%, olivine Mg# > 92, spinel Cr# up to 80, Pt/Ir < 1) to moderately depleted (Al2O3 = 2-4 wt%, olivine Mg# ?90.5, spinel Cr# < ?60). There is no systematic distribution of these domains relative to the former arc configuration and some refractory domains underlie crust that is largely devoid of magmatic rocks. Re-depletion Os model ages have no correlation with depletion indices but do have a distribution that is very similar to global convecting mantle. Whole rock, mineral and isotopic data are interpreted to show that the Zealandia mantle lithosphere was constructed from isotopically heterogeneous convecting mantle fragments swept into the sub-arc environment, amalgamated, and variably re-melted under low-P hydrous conditions. The paucity of mafic melt volumes in most of the overlying crust that could relate to the depleted domains requires melting to have been followed by lateral accretion either during subduction or slab rollback. Recent Australia-Pacific convergence has thickened portions of the Zealandia mantle to >160 km. Zealandia shows that the generation of refractory and/or thick continental lithosphere is not restricted to the Archean. Since Archean cratons also commonly display crust-mantle age decoupling, contain spinel peridotites with extreme Cr# numbers that require low-P hydrous melting, and often have a paucity of mafic melts relative to the extreme depletion indicated by their peridotitic roots, they too may - in part - be compilations of peridotite shallowly melted and then laterally accreted at subduction margins.
DS201903-0528
2019
Pearson, D.G.Luguet, A., Pearson, D.G.Dating mantle peridotites using Re-Os isotopes: the complex message from whole rocks, base metal sulfides, and platinum group minerals. ReviewAmerican Mineralogist, Vol. 104, pp. 165-189.Mantleperidotites

Abstract: The Re-Os isotopic system is largely considered the geochronometer of choice to date partial melting of terrestrial peridotites and in constraining the evolution of Earth's dynamics from the mantle viewpoint. While whole-rock peridotite Re-Os isotopic signatures are the core of such investigations, the Re-Os dating of individual peridotite minerals—base metal sulfides (BMS) and platinum group minerals (PGM)—that are the main hosts for Re and Os in the mantle peridotites came into play two decades ago. These nanometric-micrometric BMS and PGM display an extreme complexity and heterogeneity in their 187Os/188Os and 187Re/188Os signatures that result from the origin of the BMS±PGM grains (residual vs. meta-somatic), the nature of the metasomatic agents, the transport/precipitation mechanisms, BMS±PGM mineral-ogy, and subsequent Re/Os fractionation. Corresponding whole-rock host peridotites, typically plot within the 187Os/188Os and 187Re/188Os ranges defined by the BMS±PGM, clearly demonstrating that their Re-Os signatures represent the average of the different BMS±PGM populations. The difference between the 187Os/188Os ratios of the least radiogenic BMS±PGM and the respective host peridotite increases with the fertility of the peridotite reflecting the increasing contribution of metasomatic BMS±PGM to the whole-rock mass balance of Re and Os concentrations and Os isotope compositions. Corollaries to these observations are that (1) BMS may provide a record of much older partial melting event, pushing back in time the age of the lithospheric mantle stabilization, (2) if only whole-rock peridotite Re-Os isotopic measurements are possible, then the best targets for constraining the timing of lithospheric stabilization are BMS-free/BMS-poor ultra-refractory spinel-bearing peridotites with very minimal metasomatic overprint, as their 187Os/188Os signatures may be geologically meaningful, (3) while lherzolites are “fertile” in terms of their geochemical composition, they do not have a “primitive,” unmodified composition, certainly in terms of their highly siderophile elements (HSE) and Re-Os isotopic systematics, and (4) the combined Re-Os isotopic investigations of BMS and whole-rock in BMS-rich mantle peridotites would provide a complementary view on the timing and nature of the petrological events responsible for the chemical and isotopic evolution and destruction of the lithospheric mantle. In addition, the 187Os/188Os composition of the BMS±PGM (both residual and metasomatic) within any single peridotite may define several age clusters—in contrast to the single whole-rock value—and thus provide a more accurate picture of the complex petrogenetic history of the lithospheric mantle. When coupled with a detailed BMS±PGM petrographical study and whole-rock lithophile and HSE systematics, these BMS age clusters highlight the timing and nature of the petrological events contributing to the formation and chemical and isotopic evolution of the lithospheric mantle. These BMS±PGM age clusters may match regional or the local crustal ages, suggesting that the formation and evolution of the lithospheric mantle and its overlying crust are linked, providing mirror records of their geological and chemical history. This is, however, not a rule of thumb as clear evidence of crust-mantle age decoupling also exist. Although the BMS±PGM Re-Os model ages push back in time the stabilization of lithospheric mantle, the dichotomy between Archean cratonic and circum-cratonic peridotites, and post-Archean non-cratonic peridotites and tectonites is preserved. This ability of BMS±PGM to preserve older ages than their host peridotite also underscores their survival for billions of years without being reset or reequilibrated despite the complex petrogenetic processes recorded by their host mantle peridotites. As such, they are the mantle equivalents of crustal zircons. Preservation of such old signatures in “young” oceanic peridotites ultimately rules out the use of the Re-Os signatures in both oceanic peridotites and their BMS to estimate the timescales of isotopic homogenization of the convecting mantle.
DS201904-0761
2019
Pearson, D.G.Nicklas, R.W., Puchtel, I.S., Ash, R.D., Piccoli, P.M., Hanski, M., Eero, Nisbet, E.G., Waterton, P., Pearson, D.G., Anbar, A.D.Secular mantle oxidation across the Archean - Proterozoic boundary: evidence from V partitioning in komatiites and picrites.Geochimica et Cosmochimica Acta, Vol. 250, 1, pp. 49-75.Mantlepicrites

Abstract: The oxygen fugacities of nine mantle-derived komatiitic and picritic systems ranging in age from 3.55?Ga to modern day were determined using the redox-sensitive partitioning of V between liquidus olivine and komatiitic/picritic melt. The combined set of the oxygen fugacity data for seven systems from this study and the six komatiite systems studied by Nicklas et al. (2018), all of which likely represent large regions of the mantle, defines a well-constrained trend indicating an increase in oxygen fugacity of the lavas of ?1.3 ?FMQ log units from 3.48 to 1.87?Ga, and a nearly constant oxygen fugacity from 1.87?Ga to the present. The oxygen fugacity data for the 3.55?Ga Schapenburg komatiite system, the mantle source region of which was previously argued to have been isolated from mantle convection within the first 30?Ma of the Solar System history, plot well above the trend and were not included in the regression. These komatiite’s anomalously high oxygen fugacity data likely reflect preservation of early-formed magma ocean redox heterogeneities until at least the Paleoarchean. The observed increase in the oxygen fugacity of the studied komatiite and picrite systems of ?1.3 ?FMQ log units is shown to be a feature of their mantle source regions and is interpreted to indicate secular oxidation of the mantle between 3.48 and 1.87?Ga. Three mechanisms are considered to account for the observed change in the redox state of the mantle: (1) recycling of altered oceanic crust, (2) venting of oxygen from the core due to inner core crystallization, and (3) convection-driven homogenization of an initially redox-heterogeneous primordial mantle. It is demonstrated that none of the three mechanisms alone can fully explain the observed trend, although mechanism (3) is best supported by the available geochemical data. These new data provide further evidence for mantle involvement in the dramatic increase in the oxygen concentration of the atmosphere leading up to the Great Oxidation Event at ?2.4?Ga.
DS201905-1037
2019
Pearson, D.G.Guotana, J.M., Morishita, T., Yamaguschi, R., Nishio, I., Tamura, A., Tani, K., Harigane, Y., Szilas, K., Pearson, D.G.Contrasting textural and chemical signatures of chromitites in the Mesoarchean Ulamertoq peridotite body, southern west Greenland.Geosciences ( MDPI), Vol. 8, 328- 19p.Europe, Greenlandchromitite

Abstract: Peridotites occur as lensoid bodies within the Mesoarchaean orthogneiss in the Akia terrane of Southern West Greenland. The Ulamertoq peridotite body is the largest of these peridotites hosted within the regional orthogneiss. It consists mainly of olivine, orthopyroxene, and amphibole-rich ultramafic rocks exhibiting metamorphic textural and chemical features. Chromitite layers from different localities in Ulamertoq show contrasting characteristics. In one locality, zoned chromites are hosted in orthopyroxene-amphibole peridotites. Compositional zonation in chromites is evident with decreasing Cr and Fe content from core to rim, while Al and Mg increase. Homogeneous chromites from another locality are fairly uniform and Fe-rich. The mineral chemistry of the major and accessory phases shows metamorphic signatures. Inferred temperature conditions suggest that the zoned chromites, homogeneous chromites, and their hosts are equilibrated at different metamorphic conditions. In this paper, various mechanisms during the cumulus to subsolidus stages are explored in order to understand the origin of the two contrasting types of chromites.
DS201905-1073
2019
Pearson, D.G.Reimink, J.R., Pearson, D.G., Shirey, S.B., Carlson, R.W., Ketchum, J.W.F.Onset of new, progressive crustal growth in the central Slave craton at 3.55 Ga.Geochemical Perspective Letters, Vol. 10, pp. 8-13. doi:10.7185/ geochemlet.1907Canada, Northwest Territoriesmagmatism

Abstract: Ancient rock samples are limited, hindering the investigation of the processes operative on the Earth early in its history. Here we present a detailed study of well-exposed crustal remnants in the central Slave craton that formed over a 1 billion year magmatic history. The tonalitic-granodioritic gneisses analysed here are broadly comparable to common suites of rocks found in Archean cratons globally. Zircon Hf isotope data allow us to identify a major change in the way continental crust was formed in this area, with a shift to distinctly positive ?Hf starting at ~3.55 Ga. The crust production processes and spatial distribution of isotopic compositions imply variable interaction with older crust, similar to the relationships seen in modern tectonic settings; specifically, long-lived plate margins. A majority of the Slave craton might have been formed by a similar mechanism.
DS201906-1305
2019
Pearson, D.G.Kopylova, M., Tso, E., Ma, F., Liu, J., Pearson, D.G.From regional to local metasomatism in the peridotitic mantle of the Chidliak kimberlite province ( Southern Baffin Island).GAC/MAC annual Meeting, 1p. Abstract p. 124.Canada, Baffin Islanddeposit - Chidliak

Abstract: We studied the petrography, mineralogy, thermobarometry and whole rock chemistry of 120 peridotite and pyroxenite xenoliths collected from the 156 - 138 Ma Chidliak kimberlites CH-1, -6, -7 and -44. The xenoliths have higher CaO contents relative to Al2O3, and high Al for a given Mg/Si ratio compared to other cratonic peridotites. We assign the complex Ca-Al systematics of the Chidliak peridotites to repeated episodes of Ca-rich, Si-poor metasomatism, which introduced clinopyroxene and garnet, and later replaced orthopyroxene and clinopyroxene with secondary clinopyroxene and monticellite. This carbonatitic metasomatism, manifest in formation of wehrlites, acted upon the entire sampled mantle depth on a regional scale, including the proximal blocks of the North Atlantic Craton and the Chidliak mantle, where clinopyroxene and garnet modes are uniformly and heterogeneously high in the ~ 110 km deep mantle segment. Another, more recent type of mantle metasomatism, is expressed as elevated Ti in clinopyroxene and elevated Na and Ti in garnet, typical of sheared peridotites from CH-1, -7, and -44, but absent from CH-6 xenolith suite. The Ti-Na imprint is most intense in xenoliths derived from depths equivalent to 5.5 to 6.5 GPa, where it is associated with higher strain, the presence of sheared peridotites and higher temperatures varying isobarically by up to 200 °C. The horizontal scale of the thermal-metasomatic imprint is more ambiguous and could be as regional as 10's of kilometers or as local as < 1 km. The latter is constrained by the varied abundance of Ti-enriched garnets within a single kimberlite. The time-scale of this metasomatism relates to a conductive length-scale and could be as short as 100's ka, shortly predating the kimberlite formation. The Ti-Na, megacryst-like metasomatism may have resulted from a highly localized influx of hot hydrous proto-kimberlite fluids that weakened the mantle and triggered the formation of sheared peridotites.
DS201906-1314
2019
Pearson, D.G.Li, K., Li, L., Pearson, D.G., Stachel, T.Diamond isotope compositions indicate altered igneous oceanic crust dominates deep carbon recycling. Earth and Planetary Science Letters, Vol. 516, pp. 190-201.Mantlecarbon

Abstract: A long-standing unresolved problem in understanding Earth's deep carbon cycle is whether crustal carbon is recycled beyond arc depths. While isotopic signatures of eclogitic diamonds and their inclusions suggest deep recycling of crustal material, the crustal carbon source remains controversial; seafloor sediment - the widely favored crustal carbon source - cannot explain the combined carbon and nitrogen isotopic characteristics of eclogitic diamonds. Here we examined the carbon and oxygen isotopic signatures of bulk-rock carbonate for 80 geographically diverse samples from altered mafic-ultramafic oceanic crust (AOC), which comprises 95 vol% of the crustal material in subducting slabs. The results show: (i) AOC contains carbonate with C values as low as ?24‰, indicating the presence of biogenic carbonate; (ii) carbonate in AOC was mainly formed during low-temperature (<100 °C) alteration processes. Modeling accounting for this newly recognized carbon source in the oceanic crust with formation temperatures <100 °C yields a global carbon influx of 1.5±0.3 × 1012 mol C/yr carried by subducting AOC into the trench, which is 50-90% of previous estimates, but still of the same order of the carbon influx carried by subducting sediments into the trench. The AOC can retain carbon better than sediment during subduction into the asthenosphere, transition zone and lower mantle. Mixing of asthenospheric and AOC fluids provides the first consistent explanation of the diverse record of carbon and nitrogen isotopes in diamonds, suggesting that AOC, instead of sediment, is the key carrier of crustal carbon into the deep mantle.
DS201906-1354
2019
Pearson, D.G.Timmerman, S., Krebs, M.Y., Pearson, D.G., Honda, M.Diamond forming media through time - trace element and noble gas systematics of diamonds formed over 3 billion years of Earth's history.Geochimica et Cosmochimica Acta, in press available 29p.Africa, South Africa, Botswanadeposit - Koffiefontein, Letlhakane, Orapa, Finsch, De Beers Pool

Abstract: Ten individual gem-quality monocrystalline diamonds of known peridotite/eclogite paragenesis from Southern Africa (Koffiefontein, Letlhakane, Orapa) were studied for trace element concentrations and He and Ar abundances and isotopic compositions. In addition, two samples, consisting of pooled fragments of gem-quality peridotitic diamonds from Finsch and DeBeers Pool respectively, were analysed for noble gases. Previous studies (Richardson et al., 1984; Pearson et al., 1998; Gress et al., 2017; Timmerman et al., 2017) provided age constraints of 0.09, 1.0-1.1, 1.7, 2.3, and 3.2-3.4?Ga on mineral inclusions in the studied diamonds, allowing us to study trace elements and noble gases over 3 Gyr of geological time. Concentrations of trace elements in the diamonds are very low - a few hundred ppt to several tens of ppbs - and are likely dependent on the amount of sub-micron inclusions present. Trace element patterns and trace element/3He ratios of the studied monocrystalline diamonds are similar to those in fibrous diamonds, suggesting that trace elements and stable noble gas isotopes reside within the same locations in diamond and track the same processes that are reflected in the trace element patterns. We cannot discern any temporal differences in these geochemical tracers, suggesting that the processes generating them have been occurring over at least the past 2.3?Ga. 3He/4He ratios decrease and 4He and 40Ar* contents increase with increasing age of peridotitic and some eclogitic diamonds, showing the importance of in-situ radiogenic 4He and 40Ar ingrowth by the decay of U-Th-Sm and K respectively. For most gem-quality monocrystalline diamonds, uncertainties in the 3He/4He evolution of the continental lithospheric mantle combined with large analytical uncertainties and possible spatial variability in U-Th-Sm concentrations limit our ability to provide estimates of diamond formation ages using 4He ingrowth. However, the limited observed 4He ingrowth (low U?+?Th/3He) together with a R/Ra value of 5.3 for peridotitic diamond K306 is comparable to the present-day sub-continental lithospheric mantle value and supports the young diamond formation age found by Re-Os dating of sulphides in the same diamond by Pearson et al. (1998). After correction for in-situ radiogenic 4He produced since diamond formation a large variation in 3He/4He remains in ?1?Ga old eclogitic diamonds that is suggested to result from the variable influence of subducted altered oceanic crust that has low 3He/4He. Hence, the 3He/4He isotope tracer supports an origin of the diamond-forming fluids from recycled oceanic crust for eclogitic diamonds, as indicated by other geochemical proxies.
DS201906-1355
2019
Pearson, D.G.Timmerman, S., Yeow, H., Honda, M., Howell, D., Jaques, A.L., Krebs, M.Y., Woodland, S., Pearson, D.G., Avila, J.N., Ireland, T.R.U-Th/He systematics of fluid rich 'fibrous' diamonds - evidence for pre- and syn-kimberlite eruption ages.Chemical Geology, Vol. 515, pp. 22-36.Africa, Democratic Republic of Congo, Botswanadeposit - Jwaneng

Abstract: The physical characteristics and impermeability of diamonds allow them to retain radiogenic 4He produced in-situ from radioactive decay of U, Th and Sm. This study investigates the U-Th/He systematics of fibrous diamonds and provides a first step in quantification of the uncertainties associated with determining the in-situ produced radiogenic 4He concentration. Factors determining the total amount of measured helium in a diamond are the initial trapped 4He, the in-situ produced radiogenic 4He, ?-implantation, ?-ejection, diffusion, and cosmogenic 3He production. Alpha implantation is negligible, and diffusion is slow, but the cosmogenic 3He component can be significant for alluvial diamonds as the recovery depth is unknown. Therefore, samples were grouped based on similar major and trace element compositions to determine possible genetically related samples. A correlation between the 4He and U-Th concentrations approximates the initial 4He concentration at the axis-intersect and age as the slope. In this study, the corrections were applied to eight fibrous cubic diamonds from the Democratic Republic of the Congo and two diamonds from the Jwaneng kimberlite in Botswana. A correlation exists between the 4He and U-Th concentrations of the group ZRC2, 3, and 6, and of the group CNG2, 3, and 4 and both correlations deviate significantly from a 71?Ma kimberlite eruption isochron. The U-Th/He dating method appears a promising new approach to date metasomatic fluid events that result in fibrous diamond formation and this is the first evidence that some fibrous diamonds can be formed 10s to 100s Myr before the kimberlite eruption.
DS201906-1358
2019
Pearson, D.G.Veglio, C., Lawley, C., Kjarsgaard, B., Pearson, D.G.Behaviour of ore forming elements in the subcontinental lithospheric mantle below the Slave craton.GAC/MAC annual Meeting, 1p. Abstract p. 187.Canada, Northwest Territoriesdeposit - Jericho, Muskox

Abstract: The fertility of the subcontinental lithospheric mantle as source for metal-rich magmas remains poorly understood. We report new major (EPMA), minor and trace element (LA-ICP-MS) results for olivine mantle xenocrysts sourced from the Jurassic age Jericho, Muskox and Voyageur kimberlites, western Nunavut in the Slave Craton, approximately 30 km north of the Lupin gold mine. Target elements include a suite of ore-forming elements that are unconventional for mantle petrology studies, but may represent important geochemical tracers for metal metasomatism. Using single-grain aluminum-in-olivine thermometry, formation temperatures for the olivine grains were calculated and projected on to a mantle geotherm to estimate PT conditions. The suite of xenocrysts corresponds to mantle sampling between 100-190 km depth. Their range in Mg# indicates that all 3 kimberlites sampled variably depleted mantle peridotite. The patterns of trace element enrichments found are consistent with those documented previously for mantle olivine xenocryst samples from the lithosphere below the Superior Craton in Kirkland Lake, Ontario. In both studies, some ore-forming elements were found to partition into mantle silicates more at the higher temperatures and pressure prevalent at the base of the lithospheric mantle, notably copper, with concentrations varying from ~ 1 ppm in shallow samples up to 11 ppm at the maximum depth sampled. Because the concentration of metals in melt-depleted lithospheric peridotite is expected to be low (< 20 ppm Cu), mantle silicates likely become a significant host for some ore elements at depth. Highly incompatible high field strength elements yield decreasing concentrations with depth, possibly the result of mantle metasomatic processes. Fluid metasomatized mantle peridotite domains are also inferred from olivine xenocrysts that yield unexpected trace element concentrations (ppb to ppm) for other highly incompatible ore-elements (e.g. As, Mo). We expect that some of these fluid-mobile and highly incompatible ore-elements represent trapped fluid and/or melt inclusions.
DS201907-1524
2019
Pearson, D.G.Anzolini, C., Wang, F., Harris, G.A., Locock, A.J., Zhang, D., Nestola, F., Peruzzo, L., Jacobsen, S.D., Pearson, D.G.Nixonite, Na2Ti6O13, a new mineral from a metasomatized mantle garnet pyroxenite from the western Rae Craton, Darby kimberlite field, Canada.American Mineralogist, in press available 26p.Canada, Nunavutdeposit - Darby

Abstract: Nixonite (IMA 2018-133), ideally Na2Ti6O13, is a new mineral found within a heavily-metasomatized pyroxenite xenolith from the Darby kimberlite field, beneath the west central Rae Craton, Canada. It occurs as microcrystalline aggregates, 15 to 40 ?m in length. Nixonite is isostructural with jeppeite, K2Ti6O13, with a structure consisting of edge- and corner-shared titanium-centered octahedra that enclose alkali-metal ions. The Mohs hardness is estimated to be between 5 and 6 by comparison to jeppeite and the calculated density is 3.51(1) g/cm3. Electron microprobe wavelength-dispersive spectroscopic analysis (average of 6 points) yielded: Na2O 6.87, K2O 5.67 CaO 0.57, TiO2 84.99, V2O3 0.31, Cr2O3 0.04, MnO 0.01, Fe2O3 0.26, SrO 0.07, total 98.79 wt%. The empirical formula, based on 13 O atoms, is: (Na1.24K0.67Ca0.06)?1.97(Ti5.96V0.023Fe0.018)?6.00O13 with minor amounts of Cr and Mn. Nixonite is monoclinic, space group C2/m, with unit-cell parameters a = 15.3632(26) Å, b = 3.7782(7) Å, c = 9.1266(15) Å, ? = 99.35(15)º and V = 522.72(1) Å3, Z = 2. Based on the average of seven integrated multi-grain diffraction images, the strongest diffraction lines are [dobs in Å (I in %) (h k l)]: 3.02 (100) (3 1 0) , 3.66 (75) (1 1 0), 7.57 (73) (2 0 0), 6.31 (68) (2 0 -1), 2.96 (63) (3 1 -1), 2.96 (63) (2 0 -3) and 2.71 (62) (4 0 2). The five main Raman peaks of nixonite, in order of decreasing intensity, are at: 863, 280, 664, 135 and 113 cm-1. Nixonite is named after Peter H. Nixon, a renowned scientist in the field of kimberlites and mantle xenoliths. Nixonite occurs within a pyroxenite xenolith in a kimberlite, in association with rutile, priderite, perovskite, freudenbergite and ilmenite. This complex Na-K-Ti rich metasomatic mineral assemblage may have been produced by a fractionated Na-rich kimberlitic melt that infiltrated a mantle-derived garnet pyroxenite and reacted with rutile during kimberlite crystallization.
DS201908-1773
2019
Pearson, D.G.Bussweiler, Y., Giuliani, A., Greig, A., Kjarsgaard, B.A., Petts, D., Jackson, S.E., Barrett, N., Luo, Y., Pearson, D.G.Trace element analysis of high-Mg olivine by LA-ICP-MS - characterization of natural olivine standards for matrix-matched calibration and application to mantle peridotites.Chemical Geology, Vol. 524, pp. 136-157.Mantleperidotite

Abstract: The trace element composition of olivine is becoming increasingly important in petrological studies due to the ubiquity of olivine in the Earth's upper mantle and in primitive magmatic rocks. The LA-ICP-MS method allows for the routine analysis of trace elements in olivine to sub-ppm levels, but a major drawback of this method is the lack of knowledge about possible downhole fractionation effects when non matrix-matched calibration is used. In this contribution, we show that matrix-matched (i.e., olivine-based) calibration is preferable for small laser spot sizes (<100??m) due to significant laser-induced inter-element fractionation between olivine and commonly used silicate glass calibration materials, e.g., NIST SRM 612, GSD-1G and BHVO-2G. As a result, we present two Mg-rich natural olivine standards (355OL and SC-GB) that have been characterized by independent methods (EPMA, solution ICP-MS), and by LA-ICP-MS in four different laboratories. These natural olivines have been used 1) as primary standards for the matrix-matched calibration of olivine samples for most elements of interest (e.g., Li, Na, Al, P, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn), and 2) as secondary standards to assess the accuracy of results. Comparison of olivine- and silicate glass-calibrated results for natural peridotitic olivine reveals that matrix-matched calibration is essential when using small laser spot sizes (<100??m) in order to mitigate downhole fractionation effects for certain elements, especially Na, P, Mn, Co, Ni and Zn. If matrix-matched calibration is not feasible, we recommend that spot sizes of ?100??m, laser fluence of ?4.0?J/cm2, and total laser shot counts of ?250 (e.g., 5?Hz repetition rate for 50?s) are used in order to minimize fractionation effects between olivine and silicate glass calibration materials. We demonstrate the applicability of matrix-matched calibration on olivine from a suite of different mantle peridotite xenoliths sampled by kimberlites and alkali basalts from on-craton and off-craton localities.
DS201908-1783
2019
Pearson, D.G.Krebs, M.Y., Pearson, D.G.Determining the provenance pf coloured gemstones.www.minsocam.org/ MSA/Centennial/ MSA_Centennial _Symposium.html The next 100 years of mineral science, June 20-21, p. 36. AbstractAsia, Pakistan, Kashmir, South America, Colombiasapphire, emerald

Abstract: The geographic origin of gemstones has emerged as one of the major factors affecting their sale on the colored stone market, in large part due to the prestige attributed to certain regions (e.g. sapphires from Kashmir or emeralds from Colombia) but also because of political, environmental and ethical considerations. Identifying the geographic provenance of a colored stone has, therefore, developed into one of the main tasks for gem-testing laboratories, providing a strong motivation to establish accurate scientific methods. The properties and features of individual gemstones reflect the specific geological conditions of their formation and the main challenge of origin determination is to find the link between the two. In addition, access to a complete collection of authentic reference samples and analytical data for all economically relevant mining areas worldwide is key. Different techniques have been developed for determining gemstone provenance, including a range of gemological observations, and spectroscopic, chemical, and isotopic analyses[1]. These have proven useful in distinguishing the origin of gemstones from different geological settings but for many gemstones (including ruby and sapphire) to reliably distinguish between gems from different geographic regions that share a similar geological setting is not always possible. So far, no unique fingerprint exists, and the geographic origin remains a challenge, especially for high-clarity stones, emphasizing the need for a more powerful tool. Here we will give an overview of the current techniques, and outline some of the challenges and limitations of geographical origin determination of colored gemstones. In addition, we present new trace element data and the first radiogenic isotope compositions (Sr and Pb) obtained for ruby and sapphire from several different localities of geologically similar deposits. The acquisition of quantitative data of a range of ultra-trace elements along with the most commonly observed elements in ruby and sapphire (Mg, Fe, Ti, Ca, Ga, V and Cr) makes it possible to explore new elements as potential provenance discriminators. Among the elements consistently above the limits of quantification (Zn, Nb, Ni, and Pb), Ni in particular shows promise as a discriminator for amphibolite-type ruby. Measured 87Sr/86Sr and Pb isotope ratios clearly show distinct ranges for the different localities of amphibolitetype ruby, ranges for marble-related ruby and metamorphic blue sapphires from different geographic regions overlap. These results suggest that radiogenic isotopes potentially offer a powerful means of provenance discrimination for different localities of amphibolite-type ruby, their potential for geographical origin determination among marble-hosted ruby and metamorphic sapphire, however, appears to be limited.
DS201908-1802
2019
Pearson, D.G.Pearson, D.G., Stachel, T., Li, L., Li, K., Stern, R., Howell, D., Regier, M.Diamonds and their inclusions: a unique record of plate tectonic recycling. AOCwww.minsocam.org/ MSA/Centennial/ MSA_Centennial _Symposium.html The next 100 years of mineral science, June 20-21, p. 22. AbstractMantlediamond inclusions

Abstract: Much of the temporal record of Earth’s evolution, including its trace of plate tectonics, is blurred due to the dynamic nature of the crust-mantle system. While zircon provides the highest fidelity crustal record, diamond takes over in the mantle as the go-to mineral, capable of retaining critical information for a variety of geochemical proxies, over billion year timescales. Here we use diamond and its inclusions to tell the story of the recycling of C, N, O, H and B from the crust to various depths in Earth’s mantle. In this story, altered oceanic crust (AOC) and lithospheric mantle will play a prominent role. The carbon isotope record of diamond has long been thought to reflect the mixing of primitive mantle carbon with carbon recycled from isotopically light organic material originating from the crust. A major difficulty has been reconciling this view with the highly varied nitrogen and carbon isotope signatures in diamonds of eclogitic paragenesis, which cannot be interpreted by the same mechanism. Recent work on AOC of igneous origin (Li et al., EPSL in press) shows how isotopically varied carbon and nitrogen can be subducted to great depth and retained in spatial juxtaposition with the mafic silicate component of AOC to form the complex C-N isotope systematics observed in diamonds and the varied O isotope compositions of their inclusions. In this model a large portion of the 13C depleted carbon originated from biogenic carbonate within the AOC rather than from overlying sediments. Metamorphosed and partially devolatilized AOC will have very variable C/N ratios and highly variable nitrogen isotopes, explaining why simple two component mixing between organic matter and convecting upper mantle cannot explain the complexity of C-N isotope systematics in diamonds. Igneous AOC and its underlying altered mantle are considerably more efficient than subducted sediment at retaining their volatile inventory when recycled to transition zone and even lower mantle depths. Hence, this combination of mixing between AOC-derived volatiles and those from the convecting mantle produces the isotopic fingerprints of superdeep diamonds and their inclusions. These amazing diamonds, some worth millions of dollars, can contain pristine ultra-high pressure mineral phases never before seen in terrestrial samples. The first hydrous ringwoodite found in Earth provides evidence in support of a locally water-saturated transition zone that may result from altered oceanic lithospheric mantle foundering at that depth in the mantle. The O isotope composition of deep asthenosphere and transition zone phases document clearly crustal precursors that have interacted with the hydrosphere before residing hundreds of km deep within the Earth. Finally, spectacular blue diamonds contain boron, an element of strong crustal affinities, transported into the deep Earth along with crustal carbon, by the plate tectonic conveyor system. Diamond - such a simple mineral - and its inclusions, will continue to provide a unique, brightly illuminating light into the darkest recesses of Earth’s mantle for many years to come.
DS201908-1825
2019
Pearson, D.G.Wenz, M.D., Jacobsen, S.D., Zhang, D., Regier, M., Bausch, H.J., Dera, P.K., Rivers, M., Eng, P., Shirey, S.B., Pearson, D.G.Fast identification of mineral inclusions in diamond at GSECARS using synchrotron X-ray microtomography, radiography and diffraction.Journal of Synchrotron Radiation, Vol. 26, doi.org/10.1107 /S1600577519006854 6p. PdfMantlediamond inclusions

Abstract: Mineral inclusions in natural diamond are widely studied for the insight that they provide into the geochemistry and dynamics of the Earth's interior. A major challenge in achieving thorough yet high rates of analysis of mineral inclusions in diamond derives from the micrometre-scale of most inclusions, often requiring synchrotron radiation sources for diffraction. Centering microinclusions for diffraction with a highly focused synchrotron beam cannot be achieved optically because of the very high index of refraction of diamond. A fast, high-throughput method for identification of micromineral inclusions in diamond has been developed at the GeoSoilEnviro Center for Advanced Radiation Sources (GSECARS), Advanced Photon Source, Argonne National Laboratory, USA. Diamonds and their inclusions are imaged using synchrotron 3D computed X-ray microtomography on beamline 13-BM-D of GSECARS. The location of every inclusion is then pinpointed onto the coordinate system of the six-circle goniometer of the single-crystal diffractometer on beamline 13-BM-C. Because the bending magnet branch 13-BM is divided and delivered into 13-BM-C and 13-BM-D stations simultaneously, numerous diamonds can be examined during coordinated runs. The fast, high-throughput capability of the methodology is demonstrated by collecting 3D diffraction data on 53 diamond inclusions from Juína, Brazil, within a total of about 72 h of beam time.
DS201909-2074
2019
Pearson, D.G.Pernet-Fisher, J.F., Barry, P.H., Day, J.M.D., Pearson, D.G., Woodland, S., Agashev, A.M., Pokhilenko, L.N., Pokhilenko, N.P.Heterogeneous kimberlite metasomatism revealed from a combined He-Os isotope study of Siberian megacrustalline dunite xenoliths.Geochimica et Cosmochimica Acta, in press available 45p. PdfRussia, Siberiadeposit - Udachnaya East
DS201909-2098
2019
Pearson, D.G.Timmerman, S., Honda, M., Burnham, A.D., Amelin, Y., Woodland, S., Pearson, D.G., Jaques, A.L., Le Losq, C., Bennett, V.C., Bulanova, G.P., Smith, C.B., Harris, J.W., Tohver, E.Primordial and recycled helium isotope signatures in the mantle transition zone. Science, Vol. 365, 6454, pp. 692-694.Mantlediamond genesis

Abstract: Isotope compositions of basalts provide information about the chemical reservoirs in Earth’s interior and play a critical role in defining models of Earth’s structure. However, the helium isotope signature of the mantle below depths of a few hundred kilometers has been difficult to measure directly. This information is a vital baseline for understanding helium isotopes in erupted basalts. We measured He-Sr-Pb isotope ratios in superdeep diamond fluid inclusions from the transition zone (depth of 410 to 660 kilometers) unaffected by degassing and shallow crustal contamination. We found extreme He-C-Pb-Sr isotope variability, with high 3He/4He ratios related to higher helium concentrations. This indicates that a less degassed, high-3He/4He deep mantle source infiltrates the transition zone, where it interacts with recycled material, creating the diverse compositions recorded in ocean island basalts.
DS201910-2252
2019
Pearson, D.G.Czas, J., Pearson, D.G., Stachel, T., Kjarsgaard, B.A., Read, G.A diamondiferous paleoproterozoic mantle root beneath the Sask craton ( western Canada).Goldschmidt2019, 1p. AbstractCanada, Saskatchewancraton

Abstract: Primary diamond deposits are typically restricted to the stable Archean cores of continents, an association known as Clifford’s rule. Archean to Palaeoproterozoic crustal ages (3.3 - 2.1 Ga) have been reported for the Sask Craton, a small terrane in Western Canada, which hosts the diamondiferous Cretaceous Fort à la Corne (FALC) Kimberlite Field. Yet the craton is enclosed by the Palaeoproterozoic (1.9 - 1.8 Ga) Trans Hudson Orogen (THO). In this study we evaluate the age and geochemistry (major, trace, and platinum group elements data, as well as Re-Os isotope systematics) of the lithospheric mantle root beneath the Sask Craton to assess the timing of craton formation and the potential role played by the THO in its evolution. The lithospheric mantle root is dominated by lherzolite with average olivine Mg# of 91.5, which is more fertile than observed in other cratons. Garnets from concentrate further highlight the rarity of harzburgite in the lithospheric mantle. Single clinopyroxene thermobarometry provides temperaturepressure constraints for the garnet-bearing lithospheric mantle (840 to 1250 °C and 2.7 to 5.5 GPa), indicative of a cool geotherm (38 mW/m2) and a large diamond window of ~100 km thickness (from ~120-220 km depth). Most of the studied xenoliths show evidence for melt metasomatism in their trace and major element compositions, while retaining platinum group element patterns expected for melt residues. 187Os/188Os compositions span a broad range from 0.1109 to 0.1507, corresponding to Re-depletion (TRD) ages between 2.4 to 0.3 Ga, with a main mode in the Palaeoproterozoic (2.4 to 1.7 Ga). With the absence of Archean ages, the main depletion and stabilisation of the Sask Craton occurred in the Palaeoproterozoic, closely associated with the Wilson cycle of the THO. From a diamond exploration perspective this indicates that major diamond deposits can be found on cratons that were stabilised in the Palaeoproterozoic.
DS201910-2282
2019
Pearson, D.G.Liu, J., Pearson, D.G., Mather, K., Kjarsgaard, B., Kopylova, M.Destruction and regeneration of cratonic lithosphere rocks: evidence from the Slave craton, Canada.Goldschmidt2019, 1p. AbstractCanada, Northwest Territoriesgeodynamics

Abstract: Cratons are the ancient landmasses that remain stable for billions of years on Earth but also have experienced episodic events of modification and rejuvenation throughout their history [1]. These alteration processes have modified the cratonic lithospheric mantle roots to different extents, e.g., ubiquitous cryptic/modal metasomatism, partial to entire loss of the mantle roots, to rifting apart of the craton. It remains unclear to what extent a cratonic mantle root can withstand modification and retain its integrity. We attempt to discuss this issue from the perspective of the Slave craton that has experienced the multiple impacts of major circum-cratonic Paleoproterozoic (1.93-1.84 Ga) orogenies and the intrusion of several 2.23-1.67 Proterozoic diabase dyke swarms. We use kimberlite-borne peridotite xenoliths to construct a N-S transect across the craton with an aim of probing the effects of these post-Archean events on the composition, age and depth of the lithospheric root. Chemically, all of these rocks are of typical cratonic refractory composition. P-T calculations and paleogeotherms show that they were derived from thick lithospheric mantle roots (>180 km), consistent with their diamondiferous nature. However, these peridotites exhibit variable N-S variation of modes in their Re-depletion Os model ages (TRD). Neoarchean TRD ages dominate in the Central and Southern Slave mantle. Progressing North there is a decreasing proportion of Archean TRD ages through Jericho to Artemisa in the Northern Slave craton. About 70% of the peridotites at Artemisia give TRD ages within error of the ~1.27 Ga Mackenzie LIP event, with the remaining (~ 30%) close to the Paleoproterozoic orogenic events. Combined with new data from regions to the N and NW of the Slave craton [2], the observed age spectrum in the far North of the craton indicates the likelihood of major new generation of lithospheric roots in both the Paleoproterozoic and Mesoproterozoic. Despite its complex history, the Northern Slave craton retains a ‘cratonic-like’ lithospheric root that allowed diamond mineralization.
DS201910-2308
2019
Pearson, D.G.Woodhead, J., Hergt, J., Giuliani, A., Maas, R., Philips, D., Pearson, D.G., Nowell, G.Kimberlites reveal 2.5-nillion year evolution of a deep, isolated mantle reservoir.Nature, Vol. 573, pp. 578-581.Mantlemelting

Abstract: The widely accepted paradigm of Earth's geochemical evolution states that the successive extraction of melts from the mantle over the past 4.5 billion years formed the continental crust, and produced at least one complementary melt-depleted reservoir that is now recognized as the upper-mantle source of mid-ocean-ridge basalts1. However, geochemical modelling and the occurrence of high 3He/4He (that is, primordial) signatures in some volcanic rocks suggest that volumes of relatively undifferentiated mantle may reside in deeper, isolated regions2. Some basalts from large igneous provinces may provide temporally restricted glimpses of the most primitive parts of the mantle3,4, but key questions regarding the longevity of such sources on planetary timescales—and whether any survive today—remain unresolved. Kimberlites, small-volume volcanic rocks that are the source of most diamonds, offer rare insights into aspects of the composition of the Earth’s deep mantle. The radiogenic isotope ratios of kimberlites of different ages enable us to map the evolution of this domain through time. Here we show that globally distributed kimberlites originate from a single homogeneous reservoir with an isotopic composition that is indicative of a uniform and pristine mantle source, which evolved in isolation over at least 2.5 billion years of Earth history—to our knowledge, the only such reservoir that has been identified to date. Around 200 million years ago, extensive volumes of the same source were perturbed, probably as a result of contamination by exogenic material. The distribution of affected kimberlites suggests that this event may be related to subduction along the margin of the Pangaea supercontinent. These results reveal a long-lived and globally extensive mantle reservoir that underwent subsequent disruption, possibly heralding a marked change to large-scale mantle-mixing regimes. These processes may explain why uncontaminated primordial mantle is so difficult to identify in recent mantle-derived melts.
DS201911-2541
2019
Pearson, D.G.Liu, J., Pearson, D.G., Shu, Q., Sigurdsson, H., Thomassot, E., Alard, O.Dating the post-Archean lithospheric mantle: insights from Re-Os and Lu-Hf isotopic systematics of the Cameroon volcanic line peridotites.Geochimica et Cosmochimica Acta, in press available. 13p.Africa, Cameroonperidotite

Abstract: Highly depleted Archean peridotites have proven very amenable to Re-Os model age dating. In contrast, due to the increasing heterogeneity of mantle Os isotope compositions with time, the Re-Os system has not been as effective in dating post-Archean peridotites. The timing of depletion and accretion of post-Archean lithospheric mantle around cratons is important to understand within the context of the evolution of the continents. In an attempt to precisely date post-Archean peridotite xenoliths, we present a study of the petrology, mineralogy and geochemistry, including whole-rock Re-Os isotopes, highly siderophile elements and clinopyroxene-orthopyroxene Sr-Nd-Hf isotopes of peridotite xenoliths from Lake Nyos in the Cameroon Volcanic Line (CVL). Eight Nyos peridotite xenoliths, all fresh spinel lherzolites, are characterized by low to moderate olivine Fo contents (88.9-91.2) and low spinel Cr# (8.4-19.3), together with moderate to high whole-rock Al2O3 contents (2.0-3.7%). These chemical characteristics indicate that they are mantle residues of a few percent to <20% partial melting. However, trace element patterns of both clinopyroxene and orthopyroxene are not a pristine reflection of melt depletion but instead show various extents of evidence of metasomatic enrichment. Some of the samples contain orthopyroxene with 143Nd/144Nd lower than its coexisting clinopyroxene, which is best explained by recent short-timescale alteration, most likely by infiltration of the host basalt. Because of these metasomatic effects, the Sr-Nd isotope systematics in pyroxenes cannot sufficiently reflect melt depletion signatures. Unlike Sr-Nd isotopes, the Lu-Hf isotope system is less sensitive to recent metasomatic overprinting. Given that orthopyroxene hosts up to 33% of the Lu and 14% of the Hf in the whole rock budget of these rocks and has 176Hf/177Hf similar to, or higher than, coexisting clinopyroxene, it is necessary to reconstruct a whole-rock Lu-Hf isochron in order to constrain the melt depletion age of peridotites. The reconstructed Nyos Lu-Hf isochron from ortho- and clinopyroxenes gives an age of 2.01?±?0.18?Ga (1?), and when olivine and spinel are considered, is 1.82?±?0.14?Ga (1?). Both ages are identical within error, and they are within error of the alumina-187Os/188Os pseudo-isochron ages (1.2-2.4?Ga) produced on the peridotites from Lake Nyos, consistent with their oldest rhenium depletion Os model ages (2.0?Ga). We conclude that the Nyos peridotites, and the lithospheric mantle that they represent, were formed at ?2.0?Ga, indicating that the reconstructed whole-rock Lu-Hf isotope system can be a powerful radiometric dating tool that is complementary to and in some instances, more precise than the Re-Os isotope system in dating well-preserved post-Archean peridotites. The recognition of ?2.0?Ga subcontinental lithospheric mantle (SCLM) in the Nyos area suggests that the Nyos region was assembled as a Paleoproterozoic block, or that it represents fragments of the SCLM from the nearby Paleoproterozoic domain juxtaposed through collisional emplacement during the Pan African Orogeny. With regards to the origin of the CVL, our data reveal that the Hf isotopic compositions of the Nyos peridotites are too radiogenic to be the main source of the CVL basalts.
DS201911-2551
2019
Pearson, D.G.Ootes, L., Sandemann, H., Cousens, B.L.,Luo, Y., Pearson, D.G., Jackson, V.Pyroxenite magma conduits ( ca 1.86 Ga) in Wopmay orogen and Slave craton: petrogenetic constrainst from whole rock and mineral chemistry.Lithos, in press available, 54p.Canada, Northwest Territorieslamprophyres
DS201911-2575
2019
Pearson, D.G.Woodhead, J., Hergt, J., Giuliani, A., Maas, R., Phillips, D., Pearson, D.G., Nowell, G.Kimberlites reveal 2.5 billion year evolution of a deep, isolated mantle reservoir.Nature , Vol. 573, pp. 578-581.Mantlediamond genesis

Abstract: The widely accepted paradigm of Earth's geochemical evolution states that the successive extraction of melts from the mantle over the past 4.5 billion years formed the continental crust, and produced at least one complementary melt-depleted reservoir that is now recognized as the upper-mantle source of mid-ocean-ridge basalts1. However, geochemical modelling and the occurrence of high 3He/4He (that is, primordial) signatures in some volcanic rocks suggest that volumes of relatively undifferentiated mantle may reside in deeper, isolated regions2. Some basalts from large igneous provinces may provide temporally restricted glimpses of the most primitive parts of the mantle3,4, but key questions regarding the longevity of such sources on planetary timescales—and whether any survive today—remain unresolved. Kimberlites, small-volume volcanic rocks that are the source of most diamonds, offer rare insights into aspects of the composition of the Earth’s deep mantle. The radiogenic isotope ratios of kimberlites of different ages enable us to map the evolution of this domain through time. Here we show that globally distributed kimberlites originate from a single homogeneous reservoir with an isotopic composition that is indicative of a uniform and pristine mantle source, which evolved in isolation over at least 2.5 billion years of Earth history—to our knowledge, the only such reservoir that has been identified to date. Around 200 million years ago, extensive volumes of the same source were perturbed, probably as a result of contamination by exogenic material. The distribution of affected kimberlites suggests that this event may be related to subduction along the margin of the Pangaea supercontinent. These results reveal a long-lived and globally extensive mantle reservoir that underwent subsequent disruption, possibly heralding a marked change to large-scale mantle-mixing regimes. These processes may explain why uncontaminated primordial mantle is so difficult to identify in recent mantle-derived melts.
DS201912-2785
2019
Pearson, D.G.Giuliani, A., Pearson, D.G.Kimberlites: from deep Earth to diamond mines. An introduction.Elements, Vol. 15, 6, pp.Mantlediamond genesis
DS201912-2789
2019
Pearson, D.G.Heaman, L.H., Phillips, D., Pearson, D.G.Dating kimberlite: methods and emplacement patterns through time.Elements, Vol. 15, 6, pp.Mantlegeochronology
DS201912-2810
2019
Pearson, D.G.Pearson, D.G., Woodhead, J.D., Janney, P.E.Kimberlites as geochemical probes of Earth's mantle.Elements, Vol. 15, 6, pp.Mantlegeochemistry

Abstract: Kimberlites are ultrabasic, Si-undersaturated, low Al, low Na rocks rich in CO2 and H2O. The distinctive geochemical character of kimberlite is strongly influenced by the nature of the local underlying lithospheric mantle. Despite this, incompatible trace element ratios and radiogenic isotope characteristics of kimberlites, filtered for the effects of crustal contamination and alteration, closely resemble rocks derived from the deeper, more primitive, convecting mantle. This suggests that the ultimate magma source is sub-lithospheric. Although the composition of primitive kimberlite melt remains unresolved, kimberlites are likely derived from the convecting mantle, with possible source regions ranging from just below the lithosphere, through the transition zone, to the core-mantle boundary.
DS201912-2825
2020
Pearson, D.G.Shirey, S.B., Smit, K.V., Pearson, D.G., Walter, M.J., Aulbach, S., Brenker, F.E., Bureau, H., Burnham, A.D., Cartigny, P., Chacko, T., Frost, D.J., Hauri, E.H., Jacob, D.E., Jacobsen, S.D., Kohn, S.C., Luth, R.W., Mikhail, S., Navon, O., Nestola, F., NimDiamonds and the mantle geodynamics of carbon: deep mantle carbon and evolution from the diamond record.IN: Deep carbon: past to present, Orcutt, Daniel, Dasgupta eds., pp. 89-128.Mantlegeodynamics

Abstract: The science of studying diamond inclusions for understanding Earth history has developed significantly over the past decades, with new instrumentation and techniques applied to diamond sample archives revealing the stories contained within diamond inclusions. This chapter reviews what diamonds can tell us about the deep carbon cycle over the course of Earth’s history. It reviews how the geochemistry of diamonds and their inclusions inform us about the deep carbon cycle, the origin of the diamonds in Earth’s mantle, and the evolution of diamonds through time.
DS202001-0039
2020
Pearson, D.G.Shirey, S.B., Smit, K.V., Pearson, D.G., Walter, M.J., Aulbach, S., Brenker, F.E., Bureau, H., Burnham, A.D., Cartigny, P., Chacko, T., Frost, D.J., Hauri, E.H., Jacob, D.E., Jacobsen, S.D., Kohn, S.C., Luth, R.W., Mikhail, S., Navon, O., Nestola, F., NimDiamonds and mantle geodynamics of carbon: IN: Deep Carbon: past to present. Editors Orcutt, Danielle, Dasgupta, pp. 89-128.Mantlegeodynamics

Abstract: The science of studying diamond inclusions for understanding Earth history has developed significantly over the past decades, with new instrumentation and techniques applied to diamond sample archives revealing the stories contained within diamond inclusions. This chapter reviews what diamonds can tell us about the deep carbon cycle over the course of Earth’s history. It reviews how the geochemistry of diamonds and their inclusions inform us about the deep carbon cycle, the origin of the diamonds in Earth’s mantle, and the evolution of diamonds through time.
DS202002-0172
2019
Pearson, D.G.Czas, J., Pearson, D.G., Stachel, T., Kjarsgaard, B.A., Read, G.H.A Paleoproterozoic diamond bearing lithospheric mantle root beneath the Archean Sask craton, Canada.Lithos, DOI:10.1016/ j.lithos.2019.105301Canada, Saskatchewandiamond genesis

Abstract: The recently recognised Sask Craton, a small terrane with Archean (3.3-2.5 Ga) crustal ages, is enclosed in the Paleoproterozoic (1.9-1.8 Ga) Trans Hudson Orogen (THO). Only limited research has been conducted on this craton, yet it hosts major diamond deposits within the Cretaceous (~106 to ~95 Ma) Fort à la Corne (FALC) Kimberlite Field. This study describes major, trace and platinum group element data, as well as osmium isotopic data from peridotitic mantle xenoliths (n = 26) from the Star and Orion South kimberlites. The garnet-bearing lithospheric mantle is dominated by moderately depleted lherzolite. Equilibration pressures and temperatures (2.7 to 5.5 GPa and 840 to 1250 °C) for these garnet peridotites define a cool geotherm indicative of a 210 km thick lithosphere, similar to other cratons worldwide. Many of the peridotite xenoliths show the major and trace element signatures of carbonatitic and kimberlitic melt metasomatism. The Re-Os isotopic data yield TRD (time of Re-depletion) model ages, which provide minimum estimates for the timing of melt depletion, ranging from 2.4 to 0.3 Ga, with a main mode spanning from 2.4 to 1.7 Ga. No Archean ages were recorded. This finding and the complex nature of events affecting this terrane from the Archean through the Palaeoproterozoic provide evidence that the majority of the lithospheric mantle was depleted and stabilised in the Palaeoproterozoic, significantly later than the Archean crust. The timing of the dominant lithosphere formation is linked to rifting (~2.2 Ga - 2.0 Ga), and subsequent collision (1.9-1.8 Ga) of the Superior and Hearne craton during the Wilson cycle of the Trans Hudson Orogen.
DS202002-0197
2019
Pearson, D.G.Krebs, M.Y., Pearson, D.G., Fagan, A.J., Bussweiler, Y., Sarkar, C.The application of trace elements and Sr-Pb isotopes to dating and tracing ruby formation: the Aappaluttoq deposit, SW Greenland.Chemical Geology, Vol. 523, pp. 42-58.Europe, Greenlandruby

Abstract: Trace element characteristics of rubies from the Aappaluttoq deposit, SW Greenland, were measured using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), laser ablation - inductively coupled plasma-time of flight-mass spectrometry (LA-ICP-TOF-MS) and offline laser ablation followed by solution ICP-MS. LA-ICP-TOF-MS - applied to rubies for the first time - effectively maps trace element spatial variation in these gems. With the exception of a small number of elements that can substitute for Al3+ in the crystal structure (e.g., Ti, Fe, V, Cr, Mg), trace element mapping clearly demonstrates that most elements such as Th, U, Sr and Rb are hosted in mineral and fluid inclusions or are present along fractures. Primitive mantle normalized trace element patterns show characteristics that are broadly correlative to mineral inclusions within the analysed rubies. These minerals include rutile (enrichment of HFSE over LREE, high Ta/Nb and Hf/Zr ratios and low Th/U ratios), phlogopite (enrichment in Rb and Ba and positive Sr anomalies), and zircon (extreme enrichment in Zr-Hf, U and Th, HREE enrichment over LREE and positive Ce anomalies). The sample suite analysed here is derived from a bulk sample of ore composed of three different rock types (sapphirine-gedrite, leucogabbro and phlogopitite). Two different populations of ruby were identified at Aappaluttoq; these can be defined on the basis of their different V content within the corundum lattice. Therefore, V content may be able to geochemically define rubies from different host rocks within the same deposit. Using offline laser ablation followed by thermal ionization mass spectrometry (TIMS) we measured the radiogenic isotope compositions in ruby for the first time. A Pb-Pb isochron age of 2686 +300/?74?Ma, was defined for gem formation at Aappaluttoq. We believe that this is the first ever direct age determined on a ruby suite, independent of associated minerals, derived by bulk sampling sub-micron to micron sized inclusions in the corundum lattice. This age likely reflects the re-crystallization and re-setting of the ruby (and its U-Pb system) during the Neoarchean in SW Greenland, due to regional granulite to upper-amphibolite facies metamorphism.
DS202004-0519
2020
Pearson, D.G.Howell, D., Stachel, T., Stern, R.A., Pearson, D.G., Nestola, F., Hardman, M.F., Harris, J.W., Jaques, A.L., Shirery, S.B., Cartigny, P., Smit, K.V., Aulbach, S., Brenker, F.E., Jacob, D.E., Thomassot, E., Walter, M.J., Navon, O.Deep carbon through time: Earth's diamond record and its implications for carbon cycling and fluid speciation in the mantle.(peridotite and eclogite used)Geochimica et Cosmochimica Acta, Vol. 275, pp. 99-122.Mantlecarbon

Abstract: Diamonds are unrivalled in their ability to record the mantle carbon cycle and mantle fO2 over a vast portion of Earth’s history. Diamonds’ inertness and antiquity means their carbon isotopic characteristics directly reflect their growth environment within the mantle as far back as ?3.5 Ga. This paper reports the results of a thorough secondary ion mass spectrometry (SIMS) carbon isotope and nitrogen concentration study, carried out on fragments of 144 diamond samples from various locations, from ?3.5 to 1.4 Ga for P [peridotitic]-type diamonds and 3.0 to 1.0 Ga for E [eclogitic]-type diamonds. The majority of the studied samples were from diamonds used to establish formation ages and thus provide a direct connection between the carbon isotope values, nitrogen contents and the formation ages. In total, 908 carbon isotope and nitrogen concentration measurements were obtained. The total ?¹³C data range from ?17.1 to ?1.9 ‰ (P = ?8.4 to ?1.9 ‰; E = ?17.1 to ?2.1‰) and N contents range from 0 to 3073 at. ppm (P = 0 to 3073 at. ppm; E = 1 to 2661 at. ppm). In general, there is no systematic variation with time in the mantle carbon isotope record since > 3 Ga. The mode in ?¹³C of peridotitic diamonds has been at ?5 (±2) ‰ since the earliest diamond growth ?3.5 Ga, and this mode is also observed in the eclogitic diamond record since ?3 Ga. The skewness of eclogitic diamonds’ ?¹³C distributions to more negative values, which the data establishes began around 3 Ga, is also consistent through time, with no global trends apparent. No isotopic and concentration trends were recorded within individual samples, indicating that, firstly, closed system fractionation trends are rare. This implies that diamonds typically grow in systems with high excess of carbon in the fluid (i.e. relative to the mass of the growing diamond). Any minerals included into diamond during the growth process are more likely to be isotopically reset at the time of diamond formation, meaning inclusion ages would be representative of the diamond growth event irrespective of whether they are syngenetic or protogenetic. Secondly, the lack of significant variation seen in the peridotitic diamonds studied is in keeping with modeling of Rayleigh isotopic fractionation in multicomponent systems (RIFMS) during isochemical diamond precipitation in harzburgitic mantle. The RIFMS model not only showed that in water-maximum fluids at constant depths along a geotherm, fractionation can only account for variations of <1‰, but also that the principal ?¹³C mode of ?5 ± 1‰ in the global harzburgitic diamond record occurs if the variation in fO2 is only 0.4 log units. Due to the wide age distribution of P-type diamonds, this leads to the conclusion that the speciation and oxygen fugacity of diamond forming fluids has been relatively consistent. The deep mantle has therefore generated fluids with near constant carbon speciation for 3.5 Ga.
DS202005-0721
2020
Pearson, D.G.Bauer, A.M., Reimink, J.R., Chacko, T., Foley, B.J., Shirey, S.B., Pearson, D.G.Hafnium isotopes in zircons document the gradual onset of mobile-lid tectonics. ( Pilbara, Zimbabwe, Slave, Singhbhum, Rae, Wyoming, Jack HillsGeochemical Perspectives Letters, Vol. 14, pp. 1-6.GlobalTectonics

Abstract: The tectonic regime of the early Earth has proven enigmatic due to a scarcity of preserved continental crust, yet how early continents were generated is key to deciphering Earth’s evolution. Here we show that a compilation of data from 4.3 to 3.4 Ga igneous and detrital zircons records a secular shift to higher 176Hf/177Hf after ~3.8-3.6 Ga. This globally evident shift indicates that continental crust formation before ~3.8-3.6 Ga largely occurred by internal reworking of long-lived mafic protocrust, whereas later continental crust formation involved extensive input of relatively juvenile magmas, which were produced from rapid remelting of oceanic lithosphere. We propose that this secular shift in the global hafnium isotope record reflects a gradual yet widespread transition from stagnant-lid to mobile-lid tectonics on the early Earth.
DS202006-0932
2020
Pearson, D.G.Liu, J., Pearson, D.G., Shu, Q., Sigurdsson, H., Thomassot, E., Alard, O.Dating post-Archean lithospheric mantle: insights from Re-Os and Lu-Hf isotopic systematics of the Cameroon volcanic line peridotites.Geochimica et Cosmochimica Acta, Vol. 278, pp. 177-198.Africa, Cameroonperidotites

Abstract: Highly depleted Archean peridotites have proven very amenable to Re-Os model age dating. In contrast, due to the increasing heterogeneity of mantle Os isotope compositions with time, the Re-Os system has not been as effective in dating post-Archean peridotites. The timing of depletion and accretion of post-Archean lithospheric mantle around cratons is important to understand within the context of the evolution of the continents. In an attempt to precisely date post-Archean peridotite xenoliths, we present a study of the petrology, mineralogy and geochemistry, including whole-rock Re-Os isotopes, highly siderophile elements and clinopyroxene-orthopyroxene Sr-Nd-Hf isotopes of peridotite xenoliths from Lake Nyos in the Cameroon Volcanic Line (CVL). Eight Nyos peridotite xenoliths, all fresh spinel lherzolites, are characterized by low to moderate olivine Fo contents (88.9-91.2) and low spinel Cr# (8.4-19.3), together with moderate to high whole-rock Al2O3 contents (2.0-3.7%). These chemical characteristics indicate that they are mantle residues of a few percent to <20% partial melting. However, trace element patterns of both clinopyroxene and orthopyroxene are not a pristine reflection of melt depletion but instead show various extents of evidence of metasomatic enrichment. Some of the samples contain orthopyroxene with 143Nd/144Nd lower than its coexisting clinopyroxene, which is best explained by recent short-timescale alteration, most likely by infiltration of the host basalt. Because of these metasomatic effects, the Sr-Nd isotope systematics in pyroxenes cannot sufficiently reflect melt depletion signatures. Unlike Sr-Nd isotopes, the Lu-Hf isotope system is less sensitive to recent metasomatic overprinting. Given that orthopyroxene hosts up to 33% of the Lu and 14% of the Hf in the whole rock budget of these rocks and has 176Hf/177Hf similar to, or higher than, coexisting clinopyroxene, it is necessary to reconstruct a whole-rock Lu-Hf isochron in order to constrain the melt depletion age of peridotites. The reconstructed Nyos Lu-Hf isochron from ortho- and clinopyroxenes gives an age of 2.01?±?0.18?Ga (1?), and when olivine and spinel are considered, is 1.82?±?0.14?Ga (1?). Both ages are identical within error, and they are within error of the alumina-187Os/188Os pseudo-isochron ages (1.2-2.4?Ga) produced on the peridotites from Lake Nyos, consistent with their oldest rhenium depletion Os model ages (2.0?Ga). We conclude that the Nyos peridotites, and the lithospheric mantle that they represent, were formed at ?2.0?Ga, indicating that the reconstructed whole-rock Lu-Hf isotope system can be a powerful radiometric dating tool that is complementary to and in some instances, more precise than the Re-Os isotope system in dating well-preserved post-Archean peridotites. The recognition of ?2.0?Ga subcontinental lithospheric mantle (SCLM) in the Nyos area suggests that the Nyos region was assembled as a Paleoproterozoic block, or that it represents fragments of the SCLM from the nearby Paleoproterozoic domain juxtaposed through collisional emplacement during the Pan African Orogeny. With regards to the origin of the CVL, our data reveal that the Hf isotopic compositions of the Nyos peridotites are too radiogenic to be the main source of the CVL basalts.
DS202007-1123
2020
Pearson, D.G.Anzolini, C., Siva-Jothy, W., Locock, A.J., Nestola, F., Balic-Zunic, T., Alvaro, M., Stachel, T., Pearson, D.G.Heamanite-(Ce) (K0.5Ce0.5)Ti03 Mineralogical Magazine reports CNMNC Newsletter , No. 55, Vol. 84, https://doi.org/ 10.1180/mgm. 2020.39Canada, Northwest Territoriesdeposit - Gahcho Kue
DS202007-1142
2020
Pearson, D.G.Giuliani, A., Pearson, D.G., Soltys, A., Dalton, H., Phillips, D., Foley, S.F., Lim, E.Kimberlite genesis from a common primary melt modified by lithospheric mantle assimilation.Science Advances, Vol. 6, eeaz0424Mantlemelting

Abstract: Quantifying the compositional evolution of mantle-derived melts from source to surface is fundamental for constraining the nature of primary melts and deep Earth composition. Despite abundant evidence for interaction between carbonate-rich melts, including diamondiferous kimberlites, and mantle wall rocks en route to surface, the effects of this interaction on melt compositions are poorly constrained. Here, we demonstrate a robust linear correlation between the Mg/Si ratios of kimberlites and their entrained mantle components and between Mg/Fe ratios of mantle-derived olivine cores and magmatic olivine rims in kimberlites worldwide. Combined with numerical modeling, these findings indicate that kimberlite melts with highly variable composition were broadly similar before lithosphere assimilation. This implies that kimberlites worldwide originated by partial melting of compositionally similar convective mantle sources under comparable physical conditions. We conclude that mantle assimilation markedly alters the major element composition of carbonate-rich melts and is a major process in the evolution of mantle-derived magmas.
DS202008-1422
2020
Pearson, D.G.McKensie, L., Kilgore, A.H., Peslier, A.D., Brandon, L.A., Schaffer, R.V., Graff, T.G., Agresti, D.G., O'Reilly, S.Y., Griffin, W.L., Pearson, D.G., Hangi, K., Shaulis, B.J.Metasomatic control of hydrogen contents in the layered cratonic mantle lithosphere sampled by Lac de Gras xenoliths in the central Slave craton, Canada.Geochimica et Cosmochimica Acta, in press available, doi.org/101016 /j.gca.2020.07.013 45p. PdfCanada, Northwest Territoriesdeposit - Lac de Gras

Abstract: Whether hydrogen incorporated in nominally anhydrous mantle minerals plays a role in the strength and longevity of the thick cratonic lithosphere is a matter of debate. In particular, the percolation of hydrogen-bearing melts and fluids could potentially add hydrogen to the mantle lithosphere, weaken its olivines (the dominant mineral in mantle peridotite), and cause delamination of the lithosphere's base. The influence of metasomatism on hydrogen contents of cratonic mantle minerals can be tested in mantle xenoliths from the Slave Craton (Canada) because they show extensive evidence for metasomatism of a layered cratonic mantle. Minerals from mantle xenoliths from the Diavik mine in the Lac de Gras kimberlite area located at the center of the Archean Slave craton were analyzed by FTIR for hydrogen contents. The 18 peridotites, two pyroxenites, one websterite and one wehrlite span an equilibration pressure range from 3.1 to 6.6 GPa and include samples from the shallow (? 145 km), oxidized ultra-depleted layer; the deeper (?145-180 km), reduced less depleted layer; and an ultra-deep (? 180 km) layer near the base of the lithosphere. Olivine, orthopyroxene, clinopyroxene and garnet from peridotites contain 30 - 145, 110 - 225, 105 - 285, 2 - 105 ppm H2O, respectively. Within each deep and ultra-deep layer, correlations of hydrogen contents in minerals and tracers of metasomatism (for example light over heavy rare-earth-element ratio (LREE/HREE), high-field-strength-element (HFSE) content with equilibration pressure) can be explained by a chromatographic process occurring during the percolation of kimberlite-like melts through garnet peridotite. The hydrogen content of peridotite minerals is controlled by the compositions of the evolving melt and of the minerals and by mineral/melt partition coefficients. At the beginning of the process, clinopyroxene scavenges most of the hydrogen and garnet most of the HFSE. As the melt evolves and becomes enriched in hydrogen and LREE, olivine and garnet start to incorporate hydrogen and pyroxenes become enriched in LREE. The hydrogen content of peridotite increases with decreasing depth, overall (e.g., from 75 to 138 ppm H2O in the deep peridotites). Effective viscosity calculated using olivine hydrogen content for the deepest xenoliths near the lithosphere-asthenosphere boundary overlaps with estimates of asthenospheric viscosities. These xenoliths cannot be representative of the overall cratonic root because the lack of viscosity contrast would have caused basal erosion of lithosphere. Instead, metasomatism must be confined in narrow zones channeling kimberlite melts through the lithosphere and from where xenoliths are preferentially sampled. Such localized metasomatism by hydrogen-bearing melts therefore does not necessarily result in delamination of the cratonic root.
DS202008-1423
2020
Pearson, D.G.Meyer, N.A., Stachel, T., Pearson, D.G., Stern, R.A., Harris, J.W.Diamond formation from the lithosphere to the lower mantle revealed by Koffiefontein diamonds.Goldschmidt 2020, 1p. AbstractAfrica, South Africadeposit - Koffiefontein

Abstract: Because of their robust nature, diamonds survive mantle processes and protect occluded minerals since the time of diamond formation. For the Kaapvaal Craton - the archetype for craton formation and evolution - the geochemical signatures of inclusions in Koffiefontein diamonds tell a story from craton formation to evolution and from lithospheric (below about 160 km) to lower mantle (>660 km) environs. We analysed a suite of 94 lithospheric to lower mantle diamonds and their silicate and oxide inclusions. Geochemical results confirm that the diamond substrates are very depleted, with Mg#OL of 91.5-95.0 and a dominance of low-Ca (<1.8 wt% CaO), presumably dunite-derived garnet. The Si-rich nature and preserved high Mg# of the peridotitic diamond substrates beneath Koffiefontein and the formation of KNbO3 (goldschmidtite) from an extremely fractionated melt/fluid indicate that potentially both mantle- and subduction-related fluids are the cause of metasomatism in the Kaapvaal cratonic root. Mantle-like, restricted carbon isotopic compositions of both P- and E-type diamonds (avg. ?13C -5.7 ‰ and -6.6 ‰, respectively) indicate that an abundant, mantle-derived CHO fluid is responsible for diamond formation. Diamonds have a large range in nitrogen concentrations and isotopic compositions, suggesting decoupling from carbon and heterogeneous sources. ?18O of former bridgmanite and ?13C of its host diamond document a purely mantle-derived lower mantle component. Combined, these results reveal a complex and multistage evolution of the Kaapvaal Craton whereby multiple episodes of fluid and melt metasomatism re-enriched the craton already, prior to diamond formation, followed by diamond entrainment in a kimberlite possibly derived from the lower mantle.
DS202008-1429
2020
Pearson, D.G.Palmato, M.G., Nestola, F., Novella, D, Pearson, D.G., Stachel, T.In-situ mineralogical characterization of sulphide inclusions in diamonds.Goldschmidt 2020, 1p. AbstractCanada, Ontariodeposit - Victor

Abstract: Among mineral inclusions in diamond, sulphides are the most abundant. Also, they are the keel tool for dating diamond formation given their high concentration of highlysiderophile elements. However, the mineralogical nature of these inclusions is not well understood, mainly due to the exsolution of the original, high temperature monosulphide solid solution (Mss) to Fe-, Ni- and Cu-rich endmembers during cooling, obscuring the original composition. This complex exsolution observed in sulphide inclusions in diamonds can also cause problems with Re-Os age determinations if the whole inclusion is not extracted. To overcome this issue, recently, sulphide inclusions have been homogenized at high temperature and controlled oxygen fugacity [1]. However, X-ray diffraction or Raman spectroscopy analyses, required to accurately identify the inclusion phases, and define their degree of crystallographic plus compositional homogeneity, have not been reported. Here we combine for the first time a thorough nondestructive multi-technique characterization of sulphide inclusions in diamonds from the Victor Mine (Canada) with homogenization experiments and isotopic analyses. In particular, we report X-ray diffraction data of the sulphides before and after homogenization, confirming a change from a polycrystalline assemblage of pyrrothite, pentlandite and chalcopyrite to single-crystal Mss. The data are used to reconstruct the Mss’ original bulk composition, define the true bulk isotopic ratios and document any difference in Re- Os isotope systematics.
DS202008-1444
2020
Pearson, D.G.Smit, K.V., Pearson, D.G., Krebs, M.Y., Woodland, S.Trace elements of rare CH4-bearing fluids in Zimbabwe diamonds.Goldschmidt 2020, 1p. AbstractAfrica, Zimbabwedeposit - Marange

Abstract: Marange diamonds (Zimbabwe) contain both fluid-poor (gem-quality) and fluid-bearing growth zones with abundant CH4. As such, they provide the unique opportunity to compare trace element compositions of CH4-bearing diamonds with those of carbonatitic and saline high density fluid (HDF)-bearing diamonds (gem-quality and fibrous) to obtain an overview of mantle source fluids for diamond growth. HDF’s in fibrous diamonds and some gem-quality diamonds have been linked to subduction of surficial material, consistent with the global link between diamond age and collisional tectonic events. Even though Marange diamonds have +?15N indicative of surficial recycling, they do not display the expected Eu or Sr anomalies. Fibrous diamonds have the most fractionated REE patterns, with negligible HREE and high (La/Yb)N ? 100- 10000. Gem-quality diamonds have highly variable (La/Yb)N; the most unfractionated HDF’s are in Victor and Cullinan diamonds with low (La/Yb)N <76. HDF’s in Marange diamonds are intermediate between these two extremes, with (La/Yb)N = 23-240. Differences in (La/Yb)N between different diamond suites relate either to varying initial compositions (where low (La/Yb)N reflects derivation during higher degrees of melting) or to the increasing interaction of HDF’s in fibrous diamonds with mantle rocks during fluid infiltration. Marange diamonds have rare +Ce anomalies, that have so far only been reported for Victor and Brazil (sub-lithospheric) gem-quality diamonds. The oxidation state of Ce (Ce4+ vs Ce3+) and development of Ce anomalies could be attributed to ƒO2, melt/fluid composition, and PT conditions. In Marange, Victor and Brazil diamonds, Ce4+ substitution for Zr4+ does not appear to be a factor since we find no correlation between Zr content and Ce anomalies. However, in Marange diamonds, CH4-bearing zones have less variable Ce anomalies compared to the CH4-free zones, which may suggest Ce anomalies are indicative of fluid oxidation state.
DS202008-1452
2020
Pearson, D.G.Tovey, M., Giuliani, A., Phillips, D., Sarkar, C., Pearson, D.G., Nowicki, T., Carlson, J.Decoupling of kimberlite source and primitive melt compositions.Goldschmidt 2020, 1p. AbstractSouth America, Brazil, Africa, South Africa, Canada, Northwest Territoriesgeochronology

Abstract: Kimberlites emplaced since ~2 Ga show Nd and Hf isotopic compositions that follow a remarkably consistent linear evolution [1]. However, kimberlites emplaced <200 Ma within a few thousand kilometers of the western paleo-margin of Pangea (i.e. Brazil, southern Africa, and Lac de Gras in western Canada) deviate towards more enriched Nd and Hf isotopic compositions possibly due to contribution by recycled crustal material, introduced to the deep kimberlite source via subduction [1]. To address this anomaly further we have compared new and existing geochronological and Nd isotopic data for 28 kimberlites from Lac de Gras (LDG; ca. 47 - 75 Ma) with their olivine and spinel mineral chemistries. Olivine grains typically include mantle-derived xenocrystic cores (Mg# = 83.5-94.2) overgrown by magmatic rims with relatively constant Mg# values. Olivine rims and chromite are the first magmatic phases to crystallise from kimberlite and can be used as proxies for primitive melt compositions. The average Mg# of olivine cores from each kimberlite is positively correlated with average olivine rim Mg#, suggesting that assimilation of heterogeneous lithospheric mantle contributed to the primitive melt compositions. The ?Nd(i) values from whole-rock and perovskite from LDG kimberlites vary between -3.4 and -0.4 that are negatively correlated with their emplacement ages. This correlation is indicative of an evolving kimberlite source which may have resulted from a progressively lower contribution of recycled material. No systematic relationships were observed between olivine rim or chromite compositions and age or Nd isotopic composition. This observation highlights decoupling between kimberlite source evolution and primitive melt compositions due to the combined effects of crustal recycling in the kimberlite source and lithospheric mantle assimilation during kimberlite ascent.
DS202010-1872
2020
Pearson, D.G.Regier, M.E., Pearson, D.G., Stachel, T., Luth, R.W., Stern, R.A., Harris, J.W.The lithospheric-to-lower-mantle carbon cycle recorded in superdeep diamonds. ( Kankan)Nature, Vol. 585, pp. 234-238. pdfAfrica, Guineadiamond inclusions

Abstract: The transport of carbon into Earth’s mantle is a critical pathway in Earth’s carbon cycle, affecting both the climate and the redox conditions of the surface and mantle. The largest unconstrained variables in this cycle are the depths to which carbon in sediments and altered oceanic crust can be subducted and the relative contributions of these reservoirs to the sequestration of carbon in the deep mantle1. Mineral inclusions in sublithospheric, or ‘superdeep’, diamonds (derived from depths greater than 250 kilometres) can be used to constrain these variables. Here we present oxygen isotope measurements of mineral inclusions within diamonds from Kankan, Guinea that are derived from depths extending from the lithosphere to the lower mantle (greater than 660 kilometres). These data, combined with the carbon and nitrogen isotope contents of the diamonds, indicate that carbonated igneous oceanic crust, not sediment, is the primary carbon-bearing reservoir in slabs subducted to deep-lithospheric and transition-zone depths (less than 660 kilometres). Within this depth regime, sublithospheric inclusions are distinctly enriched in 18O relative to eclogitic lithospheric inclusions derived from crustal protoliths. The increased 18O content of these sublithospheric inclusions results from their crystallization from melts of carbonate-rich subducted oceanic crust. In contrast, lower-mantle mineral inclusions and their host diamonds (deeper than 660 kilometres) have a narrow range of isotopic values that are typical of mantle that has experienced little or no crustal interaction. Because carbon is hosted in metals, rather than in diamond, in the reduced, volatile-poor lower mantle2, carbon must be mobilized and concentrated to form lower-mantle diamonds. Our data support a model in which the hydration of the uppermost lower mantle by subducted oceanic lithosphere destabilizes carbon-bearing metals to form diamond, without disturbing the ambient-mantle stable-isotope signatures. This transition from carbonate slab melting in the transition zone to slab dehydration in the lower mantle supports a lower-mantle barrier for carbon subduction.
DS202011-2047
2020
Pearson, D.G.Kilgore, M.L., Peslier, A.H., Brandon, A.D., Schaffer, L.A., Morris, R.V., Graff, T.G., Agresti, D.G., O'Reilly, S.Y., Griffin, W.L., Pearson, D.G., Barry, K.G., Shaulis, J.Metasomatic control of hydrogen contents in the layered cratonic mantle lithosphere sampled by Lac de Gras xenoliths in the central Slave Craton, Canada.Geochimica et Cosmochimica Acta, Vol. 286, pp. 29-83. pdfCanada, Northwest Territoriesxenoliths

Abstract: Whether hydrogen incorporated in nominally anhydrous mantle minerals plays a role in the strength and longevity of the thick cratonic lithosphere is a matter of debate. In particular, the percolation of hydrogen-bearing melts and fluids could potentially add hydrogen to the mantle lithosphere, weaken its olivines (the dominant mineral in mantle peridotite), and cause delamination of the lithosphere's base. The influence of metasomatism on hydrogen contents of cratonic mantle minerals can be tested in mantle xenoliths from the Slave Craton (Canada) because they show extensive evidence for metasomatism of a layered cratonic mantle. Minerals from mantle xenoliths from the Diavik mine in the Lac de Gras kimberlite area located at the center of the Archean Slave craton were analyzed by FTIR for hydrogen contents. The 18 peridotites, two pyroxenites, one websterite and one wehrlite span an equilibration pressure range from 3.1 to 6.6 GPa and include samples from the shallow (?145?km), oxidized ultra-depleted layer; the deeper (?145-180?km), reduced less depleted layer; and an ultra-deep (?180?km) layer near the base of the lithosphere. Olivine, orthopyroxene, clinopyroxene and garnet from peridotites contain 30-145, 110-225, 105-285, 2-105?ppm H2O, respectively. Within each deep and ultra-deep layer, correlations of hydrogen contents in minerals and tracers of metasomatism (for example light over heavy rare-earth-element ratio (LREE/HREE), high-field-strength-element (HFSE) content with equilibration pressure) can be explained by a chromatographic process occurring during the percolation of kimberlite-like melts through garnet peridotite. The hydrogen content of peridotite minerals is controlled by the compositions of the evolving melt and of the minerals and by mineral/melt partition coefficients. At the beginning of the process, clinopyroxene scavenges most of the hydrogen and garnet most of the HFSE. As the melt evolves and becomes enriched in hydrogen and LREE, olivine and garnet start to incorporate hydrogen and pyroxenes become enriched in LREE. The hydrogen content of peridotite increases with decreasing depth, overall (e.g., from 75 to 138?ppm H2O in the deep peridotites). Effective viscosity calculated using olivine hydrogen content for the deepest xenoliths near the lithosphere-asthenosphere boundary overlaps with estimates of asthenospheric viscosities. These xenoliths cannot be representative of the overall cratonic root because the lack of viscosity contrast would have caused basal erosion of lithosphere. Instead, metasomatism must be confined in narrow zones channeling kimberlite melts through the lithosphere and from where xenoliths are preferentially sampled. Such localized metasomatism by hydrogen-bearing melts therefore does not necessarily result in delamination of the cratonic root.
DS202011-2064
2020
Pearson, D.G.Tian, G., Liu, J., Scott, J.M., Chen, L-H., Pearson, D.G., Chu, Z.Architecture and evolution of the lithospheric roots beneath circum-cratonic orogenic belts - the Xing'an Mongolian orogenic belt and its relationship with adjacent North China and Siberian cratonic roots.Lithos, Vol. 376-377, 18p. PdfChina, Russia, Siberiaxenoliths

Abstract: The accretionary mobile belts surrounding ancient cratonic cores are an important facet of the growth and preservation of continental landmasses. Peridotites from Nuominhe in the Xing'an Mongolia Orogenic Belt (XMOB) provide an additional opportunity to examine the age, structure and evolution of mantle lithosphere separating two of the largest existing ancient continental nuclei: the North China Craton and the Siberian Craton. This suite of mantle rocks comprises fertile to refractory garnet- and spinel-facies harzburgites and lherzolites. Their lithophile element systematics show that the peridotites were metasomatized to variable extent by silicate?carbonate melts. Despite this, the highly siderophile element and Os isotope systematics appear to have been largely undisturbed. The Nuominhe peridotites have Re-depletion Os model ages (TRD) that range from 0.5 Ga to 2.4 Ga, with three peaks/major ranges at ~2.0-2.4 Ga, ~1.4-1.5 Ga and ~ 0.8 Ga, of which the latter two are closely similar to those data from other XMOB localities reported in the literature. The only section of the mantle that appears to have ages which correlate with crust formation is the suite with Neoproterozoic (~0.8 Ga) depletion ages, while the older mantle domains document older episodes of mantle depletion. Given the lack of correlation between equilibrium temperatures and bulk composition or TRD ages, the Nuominhe peridotites were inter-mixed in the mantle column, most likely as a result of incorporation of recycled older continental mantle fragments into juvenile Neoproterozoic mantle during the orogenic processes responsible for new lithosphere formation. Geothermobarometry of the Nuominhe peridotites indicates a conductive geotherm of ~60 mWm?2 and therefore a lithosphere thickness of ~125 km, which is thicker than most Phanerozoic continental terranes, and even thicker than Proterozoic regions that comprise the larger cratonic unit of the Siberian craton. This thick Proterozoic lithosphere sandwiched between the converging North China and Siberian cratons was evidently partly constructed from recycled refractory continental mantle fragments, perhaps extant in the convecting mantle, or in-part derived from the surrounding cratons, leading to a composite nature of the mantle in this re-healed continental suture. Re-accretion of recycled refractory old continental mantle fragments plays a significant role in affecting mantle composition and controlling the thickness of circum-cratonic landmasses between cratonic blocks.
DS202101-0014
2020
Pearson, D.G.Gruber, B., Chacko, T., Pearson, D.G., Currie, C., Menzies, A.Heat production and moho temperatures in cratonic crust: evidence from lower crustal xenoliths from the Slave craton.Lithos, doi.org/10.1016/ j.lithos.2020.105889 13p. PdfCanada, Northwest Territoriesdeposit - Diavik A-154

Abstract: Ambient Moho temperatures and lower crustal heat production are surprisingly poorly constrained in cratons. Here we address these problems using 15 lower crustal xenoliths from the Diavik A-154 kimberlite, Slave craton, Canada. Iron?magnesium exchange geothermometry on small biotite and amphibole inclusions in garnet indicates that the Slave craton lower crust was at a temperature of ?500 °C at the time of kimberlite eruption (~55 Ma). The ambient lower crustal temperature was likely lower than 500 °C because the thermometers record the closure temperature of diffusional Fe2+-Mg exchange between touching mineral pairs. New measurements of K, U and Th concentrations in the constituent minerals, together with xenolith modes, allow reconstruction of the heat-producing element (HPE) K, U, and Th budget of the Slave craton lower crust. Metasedimentary granulites have an average heat production of 0.29 ± 0.01 ?W/m3 (n = 3) whereas mafic granulites have an average heat production of 0.13 ± 0.03 ?W/m3 (n = 12). Our new data clearly show that plagioclase abundance in both lithologies has a major influence on overall lower crustal heat production, being an important reservoir of all three HPE. Combining the heat production of mafic and metasedimentary granulites in their observed 80:20 proportions results in an average heat production value for the Slave craton lower crust of 0.16 ± 0.03 ?W/m3. Using these heat production estimates, modeled Moho temperatures beneath Diavik of ~450-470 °C are broadly consistent with maximum lower crustal temperatures indicated by geothermometry. The low HPE contents predicted for cratonic lower crust must result in lower temperatures in the deep crust and mantle lithosphere, and in turn higher estimates for the thickness of mantle lithosphere. This effect becomes larger as the thickness of the low-HPE lower crustal layer increases. In the specific case of the central Slave craton, we find that model estimates of the diamond potential of the mantle lithosphere, as judged by the proportion of lithospheric mantle in the diamond stability field, are not strongly affected by small variations in lower crustal heat production and Moho temperature.
DS202103-0383
2021
Pearson, D.G.Gress, M.U., Pearson, D.G., Chinn, I.L., Thomassot, E., Davies, G.R.Mesozoic to Paleoproterozoic diamond growth beneath Botswana recorded by Re-Os ages from individual eclogitic and websteritic inclusions.Lithos, 38p. PdfAfrica, Botswanadeposit - Orapa, Jwaneng

Abstract: Re-Os isotope systematics are reported from a suite of eclogitic and websteritic sulphide inclusions extracted from well-characterised diamond growth zones from the Orapa and Jwaneng kimberlite clusters. Re-Os ages (786 ± 250 Ma) are within uncertainty of previously determined Sm-Nd ages (853 ± 55 Ma), demonstrating isotopic equilibrium, at varying levels of completeness, across multiple isotopic systems in different minerals at the time of diamond formation and inclusion encapsulation. These data confirm the concept that inclusion isochron ages, when used with detailed textural/ growth zone control, reflect the timing of diamond crystallisation. Our data substantiate previous Re-Os and Sm-Nd inclusion ages of diamonds from Orapa and Jwaneng, indicating that major tectono-magmatic events formed discrete diamond populations of Paleo- (~ 2.0 to 1.7 Ga), Meso- (~ 1.2 to 1.1 Ga) and Neoproterozoic (~ 0.9 to 0.75 Ga) age. Some of these processes occurred simultaneously across the Kalahari Craton and can be traced over 100's of km illustrating the significance of diamond inclusions for monitoring continental tectonics. Inclusion ages indicating diamond formation that are younger than 300 Ma appear to be more common than previously recognised, consistent with evidence of relatively abundant, young, fluid-rich "fibrous" and polycrystalline diamonds at Jwaneng and Orapa. The increasingly widespread evidence for Mesozoic diamond-forming events in southern Africa and elsewhere appears closely linked with the kimberlite-related magmatism that affected these regions and subsequently transported diamonds to the surface. The inclusion isochron ages emphasise that diamond formation is a multi-stage and episodic process that can occur contemporaneously in disparate substrates and produce multiple diamond populations in the sub-continental lithospheric mantle.
DS202103-0422
2021
Pearson, D.G.Woodland, A.B., Graf, C., Sandner, T., Hofer, H.E., Seitz, H-M., Pearson, D.G., Kjarsgaard, B.A.Oxidation state and metasomatism of the lithospheric mantle beneath the Rae craton, Canada: strong gradients reflect craton formation and evolution.Nature Scientific Reports, 10.1038/s41598-021-83261-6 11p. PdfCanada, Northwest Territoriesmetasomatism

Abstract: We present the first oxidation state measurements for the subcontinental lithospheric mantle (SCLM) beneath the Rae craton, northern Canada, one of the largest components of the Canadian shield. In combination with major and trace element compositions for garnet and clinopyroxene, we assess the relationship between oxidation state and metasomatic overprinting. The sample suite comprises peridotite xenoliths from the central part (Pelly Bay) and the craton margin (Somerset Island) providing insights into lateral and vertical variations in lithospheric character. Our suite contains spinel, garnet-spinel and garnet peridotites, with most samples originating from 100 to 140 km depth. Within this narrow depth range we observe strong chemical gradients, including variations in oxygen fugacity (ƒO2) of over 4 log units. Both Pelly Bay and Somerset Island peridotites reveal a change in metasomatic type with depth. Observed geochemical systematics and textural evidence support the notion that Rae SCLM developed through amalgamation of different local domains, establishing chemical gradients from the start. These gradients were subsequently modified by migrating melts that drove further development of different types of metasomatic overprinting and variable oxidation at a range of length scales. This oxidation already apparent at ~?100 km depth could have locally destabilised any pre-existing diamond or graphite.
DS202104-0581
2021
Pearson, D.G.Gress, M.U., Pearson, D.G., Chinn, I.L., Thomassot, E., Davies, G.R.Mesozoic to Paleozoic diamond growth beneath Botswana recorded by Re-Os ages from individual eclogitic and websteritic inclusions.Appendix to previous Lithos article in March 2021, 11p. PdfAfrica, Botswanadeposit - Damtshaa, Orapa

Abstract: Re-Os isotope systematics are reported from a suite of eclogitic and websteritic sulphide inclusions extracted from well-characterised diamond growth zones from the Orapa and Jwaneng kimberlite clusters. Re-Os ages (786 ± 250 Ma) are within uncertainty of previously determined Sm-Nd ages (853 ± 55 Ma), demonstrating isotopic equilibrium, at varying levels of completeness, across multiple isotopic systems in different minerals at the time of diamond formation and inclusion encapsulation. These data confirm the concept that inclusion isochron ages, when used with detailed textural/ growth zone control, reflect the timing of diamond crystallisation. Our data substantiate previous Re-Os and Sm-Nd inclusion ages of diamonds from Orapa and Jwaneng, indicating that major tectono-magmatic events formed discrete diamond populations of Paleo- (~ 2.0 to 1.7 Ga), Meso- (~ 1.2 to 1.1 Ga) and Neoproterozoic (~ 0.9 to 0.75 Ga) age. Some of these processes occurred simultaneously across the Kalahari Craton and can be traced over 100's of km illustrating the significance of diamond inclusions for monitoring continental tectonics. Inclusion ages indicating diamond formation that are younger than 300 Ma appear to be more common than previously recognised, consistent with evidence of relatively abundant, young, fluid-rich “fibrous” and polycrystalline diamonds at Jwaneng and Orapa. The increasingly widespread evidence for Mesozoic diamond-forming events in southern Africa and elsewhere appears closely linked with the kimberlite-related magmatism that affected these regions and subsequently transported diamonds to the surface. The inclusion isochron ages emphasise that diamond formation is a multi-stage and episodic process that can occur contemporaneously in disparate substrates and produce multiple diamond populations in the sub-continental lithospheric mantle.
DS202104-0598
2021
Pearson, D.G.Pearson, D.G., Li, D., Xu, Y., Liu, S-A., Chu, Z., Chen, L-H., Li, S.Oxidation of the deep mantle wedge by recycled carbonates: constraints from highly siderophile elements and osmium isotopes.Geochimica et Cosmochimica Acta, Vol. 295, pp. 207-223.Chinanephelinites, basanites

Abstract: Widespread Cenozoic intraplate basalts from eastern China offer the opportunity to investigate the consequences of interaction between the stagnant Pacific slab and overlying asthenosphere and chemical heterogeneity within this “big mantle wedge”. We present and compile a comprehensive study of highly siderophile elements and Mg-Zn isotopes of this magmatic suite (60 samples including nephelinites, basanites, alkali basalts and tholeiites). The large-scale Mg-Zn isotopic anomalies documented in these basalts have been ascribed to mantle hybridization by recycled Mg-carbonates from the stagnant western Pacific plate. Our results reveal that the nephelinites and basanites are characterized by unfractionated platinum-group element (PGE) patterns normalized to primitive upper mantle (PUM) (e.g., PdN/IrN normalized to PUM?=?1.1?±?0.8, 1?), relatively high total PGE contents (e.g., Ir?=?0.25?±?0.14?ppb) and modern mantle-like 187Os/188Os (0.142?±?0.020). These characteristics are coupled with lighter Mg isotope (?26Mg?=??0.48?±?0.07‰) and heavier Zn isotope (?66Zn = +0.46?±?0.06‰) compositions compared to the mantle values (?26Mg: ?0.25?±?0.07‰; ?66Zn: +0.18?±?0.05‰). Together, these data are interpreted to reflect the oxidative breakdown of low proportions of mantle sulfides in the sources of these small-degree melts, likely caused by recycled carbonates, which then release chalcophile-siderophile elements into carbonatitic melts. By contrast, the contemporaneous alkali basalts and tholeiites are characterized by highly fractionated PGE patterns (e.g., PdN/IrN?=?4.4?±?3.3; Ir?=?0.037?±?0.027?ppb) and radiogenic 187Os/188Os (0.279?±?0.115) coupled with less fractionated Mg-Zn isotope compositions (?26Mg: ?0.39?±?0.05‰; ?66Zn: +0.35?±?0.03‰). In combination with other isotopic (e.g., Sr-Nd) and chemical (SiO2, Ce/Pb, Ba/Th, Fe/Mn) constraints, the alkali basalts and tholeiites were derived from higher degree melting of ancient pyroxenite-bearing mantle in addition to mixing with the aforementioned nephelinitic and basanitic melts. Collectively, we suggest that deep recycled carbonates promoted melting within the "big mantle wedge" leading to the generation of Cenozoic intraplate basalts across eastern China and the "redox freezing of carbonates" may cause the oxidation of Fe0 and S2-. This process may provide an important mechanism to oxidize mantle sulfides and transfer precious metals from deep mantle to crust.
DS202105-0774
2021
Pearson, D.G.Liu, J., Pearson, D.G., Wang, L.H., Mather, K.A., Kjarsgaard, B.A., Schaeffer, A.J., Irvine, G.J., Kopylova, M.G., Armstrong, J.P.Plume-driven recratonization of deep continental lithospheric mantle.Nature, doi.org/101038/ s41586-021-03395-5 5p. PdfCanada, Northwest Territoriescraton

Abstract: Cratons are Earth’s ancient continental land masses that remain stable for billions of years. The mantle roots of cratons are renowned as being long-lived, stable features of Earth’s continents, but there is also evidence of their disruption in the recent1,2,3,4,5,6 and more distant7,8,9 past. Despite periods of lithospheric thinning during the Proterozoic and Phanerozoic eons, the lithosphere beneath many cratons seems to always ‘heal’, returning to a thickness of 150 to 200 kilometres10,11,12; similar lithospheric thicknesses are thought to have existed since Archaean times3,13,14,15. Although numerous studies have focused on the mechanism for lithospheric destruction2,5,13,16,17,18,19, the mechanisms that recratonize the lithosphere beneath cratons and thus sustain them are not well understood. Here we study kimberlite-borne mantle xenoliths and seismology across a transect of the cratonic lithosphere of Arctic Canada, which includes a region affected by the Mackenzie plume event 1.27 billion years ago20. We demonstrate the important role of plume upwelling in the destruction and recratonization of roughly 200-kilometre-thick cratonic lithospheric mantle in the northern portion of the Slave craton. Using numerical modelling, we show how new, buoyant melt residues produced by the Mackenzie plume event are captured in a region of thinned lithosphere between two thick cratonic blocks. Our results identify a process by which cratons heal and return to their original lithospheric thickness after substantial disruption of their roots. This process may be widespread in the history of cratons and may contribute to how cratonic mantle becomes a patchwork of mantle peridotites of different age and origin.
DS202105-0781
2021
Pearson, D.G.Pamato, M.G., Novella, D., Jacobs, D.E., Oliveira, B., Pearson, D.G., Greene, S., Alfonso, J.C., Favero, M., Stachel, T., Alvaro, M., Nestola, F.Protogenetic sulfide inclusions in diamonds date the diamond formation event using Re-Os isotopes. Victor, JerichoGeology , Vol. 49, 4, 5p. Canada, Ontario, Nunavutdiamond inclusions

Abstract: Sulfides are the most abundant inclusions in diamonds and a key tool for dating diamond formation via Re-Os isotopic analyses. The manner in which fluids invade the continental lithospheric mantle and the time scale at which they equilibrate with preexisting (protogenetic) sulfides are poorly understood yet essential factors to understanding diamond formation and the validity of isotopic ages. We investigated a suite of sulfide-bearing diamonds from two Canadian cratons to test the robustness of Re-Os in sulfide for dating diamond formation. Single-crystal X-ray diffraction (XRD) allowed determination of the original monosulfide solid-solution (Mss) composition stable in the mantle, indicating subsolidus conditions of encapsulation, and providing crystallographic evidence supporting a protogenetic origin of the inclusions. The results, coupled with a diffusion model, indicate Re-Os isotope equilibration is sufficiently fast in sulfide inclusions with typical grain size, at mantle temperatures, for the system to be reset by the diamond-forming event. This confirms that even if protogenetic, the Re-Os isochrons defined by these minerals likely reflect the ages of diamond formation, and this result highlights the power of this system to date the timing of fluid migration in mantle lithosphere.
DS202107-1117
2021
Pearson, D.G.Nakanishi, N., Giuliani, A., Carlson, R.W., Horan, M.F., Woodhead, J., Pearson, D.G., Walker, R.J.Tungsten-182 evidence for an ancient kimberlite source.PNAS, Vol. 118, no. 23, doi.org/10.1073/pnas .e2020680118 8p. PdfMantledeep source, genesis

Abstract: Globally distributed kimberlites with broadly chondritic initial 143Nd-176Hf isotopic systematics may be derived from a chemically homogenous, relatively primitive mantle source that remained isolated from the convecting mantle for much of the Earth’s history. To assess whether this putative reservoir may have preserved remnants of an early Earth process, we report 182W/184W and 142Nd/144Nd data for "primitive" kimberlites from 10 localities worldwide, ranging in age from 1,153 to 89 Ma. Most are characterized by homogeneous ?182W and ?142Nd values averaging ?5.9 ± 3.6 ppm (2SD, n = 13) and +2.7 ± 2.9 ppm (2SD, n = 6), respectively. The remarkably uniform yet modestly negative ?182W values, coupled with chondritic to slightly suprachondritic initial 143Nd/144Nd and 176Hf/177Hf ratios over a span of nearly 1,000 Mya, provides permissive evidence that these kimberlites were derived from one or more long-lived, early formed mantle reservoirs. Possible causes for negative ?182W values among these kimberlites include the transfer of W with low ?182W from the core to the mantle source reservoir(s), creation of the source reservoir(s) as a result of early silicate fractionation, or an overabundance of late-accreted materials in the source reservoir(s). By contrast, two younger kimberlites emplaced at 72 and 52 Ma and characterized by distinctly subchondritic initial 176Hf/177Hf and 143Nd/144Nd have ?182W values consistent with the modern upper mantle. These isotopic compositions may reflect contamination of the ancient kimberlite source by recycled crustal components with ?182W ? 0.
DS202107-1128
2019
Pearson, D.G.Shirey, S.B., Smit, K.V., Pearson, D.G., Walter, M.J., Aulbach, S., Brenker, F.E., Bureau, H., Burnham, A.D., Cartigny, P., Chacko, T., Frost, D.J., Hauri, E.H., Jacob, D.E., Jacobsen, S.D., Kohn, S.C., Luth, R.W., Mikhail, S., Navon, O.. Nestola, F., NimDiamonds and mantle geodynamics of carbon.Deep Carbon - Cambridge University Press , Cambridge.org 40p. PdfMantlecarbon
DS202107-1129
2021
Pearson, D.G.Shirey, S.B., Wagner, L.S., Walter, M.J., Pearson, D.G., van Keken, P.E.Slab transport of fluids to deep focus earthquake depths - thermal modeling constraints and evidence from diamonds.AGU, 10.1029/2020AV000304 28p. PdfMantleinclusions, geothermometry

Abstract: Earthquakes occurring below ?300 km, especially in the mantle transition zone are some of the strongest events experienced on Earth. Deep earthquakes, whose nature and cause are poorly known, occur with regularity and are a deep and prominent result of plate tectonics. We model the paths of subducting slabs to relate pressure-temperature conditions to the experimentally determined mineralogies of the slab crust and mantle. We present a synthesis of mantle minerals included in diamonds derived from same depths as the deep earthquakes to show that fluids exist there. We show that decarbonization/melting reactions in the slab crust and dehydration reactions in the slab mantle can provide fluids to the earthquake generation regions, suggesting that fluids cause or are related to deep earthquakes.
DS202108-1302
2021
Pearson, D.G.Pamato, M.G., Novella, D., Jacob, B., Oliveira, B., Pearson, D.G.Petrogenetic sulfide inclusions in diamonds date the diamond formation event using Re-Os isotopes.Geology, Vol. 49, pp. 941-945.Canada, Ontario, Nunavutdeposit - Victor, Jericho

Abstract: Sulfides are the most abundant inclusions in diamonds and a key tool for dating diamond formation via Re-Os isotopic analyses. The manner in which fluids invade the continental lithospheric mantle and the time scale at which they equilibrate with preexisting (protogenetic) sulfides are poorly understood yet essential factors to understanding diamond formation and the validity of isotopic ages. We investigated a suite of sulfide-bearing diamonds from two Canadian cratons to test the robustness of Re-Os in sulfide for dating diamond formation. Single crystal X-ray diffraction (XRD) allowed determination of the original monosulfide solid-solution (Mss) composition stable in the mantle, indicating subsolidus conditions of encapsulation, and providing crystallographic evidence supporting a protogenetic origin of the inclusions. The results, coupled with a diffusion model, indicate Re-Os isotope equilibration is sufficiently fast in sulfide inclusions with typical grain size, at mantle temperatures, for the system to be reset by the diamond-forming event. This confirms that even if protogenetic, the Re-Os isochrons defined by these minerals likely reflect the ages of diamond formation, and this result highlights the power of this system to date the timing of fluid migration in mantle lithosphere.
DS202109-1484
2021
Pearson, D.G.Pearson, D.G., Scott, J.M., Liu, J., Schaeffer, A., Wang, L.H., van Hunen, J., Szilas, K., Chacko, T., Kelemen, P.B. Deep continental roots and cratons.Nature, Vol. 596, pp. 199-210. pdfGlobalcratons

Abstract: The formation and preservation of cratons-the oldest parts of the continents, comprising over 60 per cent of the continental landmass-remains an enduring problem. Key to craton development is how and when the thick strong mantle roots that underlie these regions formed and evolved. Peridotite melting residues forming cratonic lithospheric roots mostly originated via relatively low-pressure melting and were subsequently transported to greater depth by thickening produced by lateral accretion and compression. The longest-lived cratons were assembled during Mesoarchean and Palaeoproterozoic times, creating the stable mantle roots 150 to 250 kilometres thick that are critical to preserving Earth’s early continents and central to defining the cratons, although we extend the definition of cratons to include extensive regions of long-stable Mesoproterozoic crust also underpinned by thick lithospheric roots. The production of widespread thick and strong lithosphere via the process of orogenic thickening, possibly in several cycles, was fundamental to the eventual emergence of extensive continental landmasses-the cratons.
DS202110-1618
2021
Pearson, D.G.Haugaard, R., Waterton, P., ootes, L., Pearson, D.G., Luo,Y., Konhauser, K.Detrital chromites reveal Slave craton's missing komatite.Geology, Vol. 49, 9, pp. 1079-1083. pdfCanada, Northwest Territorieschromites

Abstract: Komatiitic magmatism is a characteristic feature of Archean cratons, diagnostic of the addition of juvenile crust, and a clue to the thermal evolution of early Earth lithosphere. The Slave craton in northwest Canada contains >20 greenstone belts but no identified komatiite. The reason for this dearth of komatiite, when compared to other Archean cratons, remains enigmatic. The Central Slave Cover Group (ca. 2.85 Ga) includes fuchsitic quartzite with relict detrital chromite grains in heavy-mineral laminations. Major and platinum group element systematics indicate that the chromites were derived from Al-undepleted komatiitic dunites. The chromites have low 187Os/188Os ratios relative to chondrite with a narrow range of rhenium depletion ages at 3.19 ± 0.12 Ga. While these ages overlap a documented crust formation event, they identify an unrecognized addition of juvenile crust that is not preserved in the bedrock exposures or the zircon isotopic data. The documentation of komatiitic magmatism via detrital chromites indicates a region of thin lithospheric mantle at ca. 3.2 Ga, either within or at the edge of the protocratonic nucleus. This study demonstrates the applicability of detrital chromites in provenance studies, augmenting the record supplied by detrital zircons.
DS202112-1929
2021
Pearson, D.G.Hardman, M.F., Stachel, T., Pearson, D.G., Cano, E.J., Stern, R.A., Sharp, Z.D.Characterising the distinct crustal protoliths of Roberts Victor Type I and II eclogites.Journal of Petrology, doi.org/petrology/egab090 65p. PdfAfrica, South Africadeposit - Roberts Victor

Abstract: The origin of the eclogites that reside in cratonic mantle roots has long been debated. In the classic Roberts Victor kimberlite locality in South Africa, the strongly contrasting textural and geochemical features of two types of eclogites have led to different genetic models. We studied a new suite of 63 eclogite xenoliths from the former Roberts Victor Mine. In addition to major- and trace-element compositions for all new samples, we determined 18O/16O for garnet from 34 eclogites. Based on geochemical and textural characteristics we identify a large suite of Type I eclogites (n = 53) consistent with previous interpretations that these rocks originate from metamorphosed basaltic-picritic lavas or gabbroic cumulates from oceanic crust, crystallised from melts of depleted MORB mantle. We identify a smaller set of Type II eclogites (n = 10) based on geochemical and textural similarity to eclogites in published literature. We infer their range to very low ?18O values combined with their varied, often very low Zr/Hf ratios and LREE-depleted nature to indicate a protolith origin via low-pressure clinopyroxene-bearing oceanic cumulates formed from melts that were more depleted in incompatible elements than N-MORB. These compositions are indicative of derivation from a residual mantle source that experienced preferential extraction of incompatible elements and fractionation of Zr-Hf during previous melting.
DS202204-0527
2022
Pearson, D.G.Lai, M.Y., Stachel, T., Stern, R.A., Hardman, M.F., Pearson, D.G., Harris, J.W.Formation of mixed paragenesis diamonds during multistage growth - constraints from- in situ Delta 13C-delta 15N-[N] analyses of Koidu diamonds.Geochimica et Cosmochimica Acta, Vol. 323, pp. 20-39.Africa, Sierra Leonedeposit - Koidu

Abstract: Inclusion-bearing diamonds from the Koidu kimberlite complex, Sierra Leone (West African Craton) were analyzed in situ for carbon and nitrogen isotope compositions, nitrogen concentrations and nitrogen aggregation states. In a suite of 105 diamonds, 78% contain eclogitic mineral inclusions, 17% contain peridotitic mineral inclusions, and 5% - an unusually high proportion - contain co-occurring eclogitic and peridotitic mineral inclusions indicating a mixed paragenesis. Major and trace element compositions of mineral inclusions from two mixed paragenesis diamonds (one with omphacite + Mg-chromite, the other with eclogitic garnet + forsteritic olivine) were determined. The presence of positive Eu anomalies in centrally located omphacite and eclogitic garnet inclusions indicates derivation from subducted protoliths, formed as igneous cumulates in lower oceanic crust. Mg-chromite (Cr# 85.5; Mg# 65.2) and olivine (Mg# 94.5) inclusions, located in outer portions of the mixed paragenesis diamonds, have compositions indicative of derivation from strongly depleted cratonic peridotites. Given that the olivine Mg# of 94.5 is the highest reported to date for the West African Craton, the eclogitic and peridotitic inclusions in these mixed paragenesis diamonds cannot have precipitated during infiltration of peridotitic substrates by eclogite-derived fluids, as the consequent fluid-rock interaction should lead to Mg# lower than that for the original peridotitic diamond substrate. The different origins of eclogitic and peridotitic inclusions could be explained by physical transport of their host diamonds from eclogitic into peridotitic substrates, possibly along high-strain shear zones, before renewed diamond growth. Based on the ?¹³C-?¹?N systematics of the entire inclusion-bearing diamond suite from Koidu, three major compositional clusters are identified. Cluster 1 (eclogitic diamond cores; ?¹³C = -33.2 to -14.4 ‰ and ?¹?N = -5.3 to +10.1 ‰) bears the isotopic signature of recycled crustal material (± a mantle component). Cluster 2 (peridotitic diamonds and including the core of a diamond containing omphacite + Mg-chromite; ?¹³C = -6.0 to -1.1 ‰ and ?¹?N = -4.2 to +9.7 ‰) likely involves mixing of carbon and nitrogen from subducted and mantle sources. Cluster 3 (rims of eclogitic diamonds and including the eclogitic garnet + olivine included diamond and the rim of the omphacite + Mg-chromite included diamond; ?¹³C = -7.8 to -3.6 ‰ and ?¹?N = -7.9 to -2.1 ‰) matches convecting mantle-derived fluids/melts. The distinct isotopic signatures of the three diamond clusters, together with differences in nitrogen aggregation and cathodoluminescence response between diamond cores and rims, suggest episodic diamond growth during multiple fluid/melt pulses.
DS202205-0723
2022
Pearson, D.G.Tovey, M., Giuliani, A., Phillips, D., Nowicki, T., Pearson, D.G., Fedorchouk, Y., Russell, J.K.Controls on the emplacement style of coherent kimberlites in the Lac de Gras Field, Canada.Journal of Petrology, 10.1093/petrology/egac028/6553928 24p. pdf Canada, Northwest Territoriesdeposit - Lac de Gras

Abstract: In the Lac de Gras (LDG) kimberlite field, Northwest Territories, Canada, coherent kimberlites (CKs) occur as tabular dykes, pipe-shaped diatremes, and irregular bodies without well-defined geometries. Combining the morphology of CK bodies with the occurrence of fragmented olivine microcrysts allows distinction of four CK types at LDG: (1) dykes with no broken olivine; (2) CK without well-defined but probable sheet geometry and no broken olivine; (3) pipe-filling CK (pfCK) with abundant broken olivine and (4) pfCK with no broken olivine. These features suggest an intrusive origin for type 1 and, probably, type 2 CK; a high-energy extrusive emplacement for CK type 3 and a low-energy intrusive or extrusive emplacement for the CK type 4. Here, we compare petrographic and whole-rock, olivine and spinel compositional data for high-energy extrusive pfCK, low-energy pfCK and intrusive CK units to understand the factors controlling their variable emplacement styles. Extrusive CK contain more abundant groundmass phlogopite and monticellite, lower carbonate/silicate mineral abundance ratios and significantly lower dolomite and pleonaste-spinel abundances compared to intrusive CK. This indicates greater CO2 loss and higher H2O/CO2 in the melt phase for the extrusive CK during emplacement. Lower incompatible element concentrations in the extrusive CKs and different chromite Ti# and olivine rim Mg# indicate derivation from distinct primitive melt compositions. The extrusive CK feature higher ?Ndi and marginally higher ?Hfi compositions than the intrusive CK, pointing to derivation from distinct sources. These findings strongly imply that distinct primary melt compositions were largely responsible for the differences in emplacement styles of CK at LDG. Low-energy pfCKs have similar olivine rim Mg#, chromite Ti# and, hence, primitive melt compositions to the high-energy extrusive CK samples. Their marginally different emplacement styles may depend on local factors, such as changing stress regimes, or slightly different volatile concentrations. Both types of pfCK might reflect the waning stages of volcanic sequences resulting from the eruption of a segregated magma column that started with pipe excavation and the explosive emplacement of gas-rich magma (volcaniclastic kimberlite), followed by the less energetic emplacement of melt-rich magma (pfCK). This hypothesis underscores different primary melt compositions for dyke vs pipe-forming (and filling) kimberlites and hence a fundamental primary melt control on the explosivity of kimberlites.
DS200712-0823
2006
Pearson, D.J.Pearson, D.J., O'Reilly, S.Y., Griffin, W.L., Alard, O., Belousova, E.Linking crustal and mantle events using in situ trace element and isotope analysis.Geochimica et Cosmochimica Acta, In press availableMantleGeochronology
DS200812-0705
2008
Pearson, D.J.Malarkey, J., Pearson, D.J., Nowell, G.M., Davidson, J.P., Ottley, C.J., Kjarsgaard, B., Mitchell, R.H., Kopylova, M.Constraining the crust and mantle contributions to kimberlite - a multi phase micro sampling approach.9IKC.com, 3p. extended abstractCanada, OntarioDeposit - C 14 perovskite crystals
DS201312-0337
2013
Pearson, D.J.Griffin, W.L., Yang, J.S., Robinson, P., Howell, D., Shi, R., O'Reilly, S.Y., Pearson, D.J.Diamonds and super reducing UHP assemblages in ophiolitic mantle, Tibet: where are the eclogites?X International Eclogite Conference, 1p. abstractAsia, TibetDiamond genesis
DS1998-0154
1998
Pearson, D.R.Boyd, F.R., Pearson, D.R., Mertzman, S.A.Spinel facies peridotites from the Kaapvaal root7th International Kimberlite Conference Abstract, pp. 100-102.South Africa, LesothoPeridotites - spinel, Deposit - Premier, Kimberley, Letseng, Frank Smith, Wel
DS202112-1931
2021
Pearson, D.R.Kaempfer, K.M., Guentthner, W.R., Pearson, D.R.Proterozoic to Phanerozoic tectonism in southwestern Montana basement and ranges constrained by low temperature thermochronometric data.Tectonics, Vol. 40, 11 22021TC006744United States, Montanageothermometry

Abstract: Crystalline basement rocks of southwestern Montana have been subjected to multiple tectonothermal events since ?3.3 Ga: the Paleoproterozoic Big Sky/Great Falls orogeny, Mesoproterozoic extension associated with Belt-Purcell basin formation, Neoproterozoic extension related to Rodinia rifting, and the late Phanerozoic Sevier-Laramide orogeny. We investigated the long-term (>1 Ga), low-temperature (erosion/burial within 10 km of the surface) thermal histories of these tectonic events with zircon and apatite (U-Th)/He thermochronology. Data were collected across nine sample localities (n = 55 zircon and n = 26 apatite aliquots) in the northern and southern Madison ranges, the Blacktail-Snowcrest arch, and the Tobacco Root uplift. Our zircon (U-Th)/He data show negative trends between single aliquot date and effective uranium (a radiation damage proxy), which we interpreted with a thermal history model that considers the damage-He diffusivity relationship in zircon. Our model results for these basement ranges show substantial cooling from temperatures above 400°C to near surface conditions between 800 and 510 Ma. Subsequent Phanerozoic exhumation culminated by ?75 Ma. Late Phanerozoic cooling is coincident with along-strike Sevier belt thin-skinned thrusting in southeastern Idaho, and older than exhumation in basement-involved uplifts of the Wyoming Laramide province. Our long-term, low-temperature thermal record for these southwestern Montana basement ranges shows that: (a) these basement blocks have experienced multiple episodes of upper crustal exhumation and burial since Archean time, possibly influencing Phanerozoic thrust architecture and (b) the late Phanerozoic thick-skinned thrusting recorded by these rocks is among the earliest thermochronologic records of Laramide basement-involved shortening and was concomitant with Sevier belt thin-skinned thrusting.
DS1983-0510
1983
Pearson, G.Pearson, G.Seismic Gem ProspectingAustralian Gemologist., Vol. 15, No. 1, PP. 17-18.AustraliaDiamonds
DS1994-0387
1994
Pearson, G.Davies, G.R., Nixon, P.H., Pearson, G., Obata, M.Octahedral graphite bearing pyroxenites from Ronda, S. SpainProceedings of Fifth International Kimberlite Conference, Vol. 1, pp. 318-326.GlobalPyroxenites, Ronda
DS2002-0678
2002
Pearson, G.Hauri, E., Bulanova, G., Pearson, G., Griffin, B.Carbon and nitrogen isotope systematics in a sector zoned diamond from the Mir kimberlite, Yakutia.Eos, American Geophysical Union, Spring Abstract Volume, Vol.83,19, 1p.Russia, YakutiaGeochronology - diamond morphology, Deposit - Mir
DS201312-0693
2013
Pearson, G.Pearson, G.How much Archean lithospheric mantle is there in Arctic Canada?GEM Diamond Workshop Feb. 21-22, Noted onlyCanadaPetrology
DS201702-0231
2017
Pearson, G.Pearson, G.The complex history of the mantle roots beneath the Slave Craton and surrounding regions.Vancouver Kimberlite Cluster, Jan. 26, 1/4p. AbstractCanada, Northwest Territories, NunavutGeochronology
DS201705-0870
2017
Pearson, G.Pearson, G., Krebs, M., Stachel. T., Woodland, S., Chinn, I., Kong, J.Trace elements in gem-quality diamonds: origin and evolution of diamond-forming fluid inclusions.European Geosciences Union General Assembly 2017, Vienna April 23-28, 1p. 19281 AbstractTechnologyDiamond inclusions
DS201708-1730
2017
Pearson, G.Pearson, G.Trace elements in gem quality diamonds from the De Beers Victor mine, Ontario, Canada.11th. International Kimberlite Conference, PosterCanada, Ontario, Attawapiskatdeposit - Victor
DS201709-1968
2017
Pearson, G.Bussweiler, Y., Poitras, S., Borovinskaya, O., Tanner, M., Pearson, G.Rapid multielemental analysis of garnet with LA-ICP-TOF-MS implications for diamond exploration studies.Goldschmidt Conference, abstract 1p.Canada, Northwest Territoriesdiamond potential

Abstract: Garnet arguably constitutes the most important mineral in diamond exploration studies; not only can the presence of mantle garnet in exploration samples point to kimberlite occurrences, but its minor and trace element composition can further be used to assess the “diamond potential” of a kimberlite. The content of Cr and Ca, especially, has been found to be a reliable tool to test whether garnets originate from within the diamond stability field in the mantle [1]. Trace element patterns can further indicate the mantle host rock of the garnets, for example, whether they originate from a depleted or ultra-depleted mantle section [2]. Routinely, two separate analytical methods are necessary to fully characterize the composition of garnet; major and minor elements are usually determined by electron probe micro-analysis (EPMA), whereas determination of trace elements requires the more sensitive method of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Here, we demonstrate rapid measurement of the entire suite of elements in garnet employing a new, commercially available timeof-flight (TOF) mass spectrometer, the icpTOF (TOFWERK AG, Thun, Switzerland), coupled to a fast wash-out laser ablation system (Teledyne Cetac Technologies Inc., Omaha, NE, USA). Using garnets from exploration samples taken from the Horn Plateau, Northwest Territories, Canada [3], we directly compare the icpTOF results to EPMA and LA-ICP-MS data. We examine whether the icpTOF can reliably characterize the garnets in Cr versus Ca space and at the same time reproduce their trace element patterns, thereby offering a cost effective method of analysis. The method of LA-ICP-TOF-MS, with its high speed of data acquisition and its ability to record the entire mass spectrum simultaneously, may have great benefits for (diamond) exploration studies. Moreover, the method can be used for fast, highresolution imaging, which is applicable to a wide range of geological materials and settings [4].
DS201811-2575
2018
Pearson, G.Guotana, J.M., Morishita, T., Yamaguchi, R., Nishio, I., Tamura, A., Harigane, Y., Szilas, K., Pearson, G.Contrasting textural and chemical signatures of chromitites in the Mesoarchean Ulamertoq peridotite body, southern West Greenland.Geosciences, Vol. 8, no. 9, p. 328-Europe, Greenlandperidotite

Abstract: Peridotites occur as lensoid bodies within the Mesoarchaean orthogneiss in the Akia terrane of Southern West Greenland. The Ulamertoq peridotite body is the largest of these peridotites hosted within the regional orthogneiss. It consists mainly of olivine, orthopyroxene, and amphibole-rich ultramafic rocks exhibiting metamorphic textural and chemical features. Chromitite layers from different localities in Ulamertoq show contrasting characteristics. In one locality, zoned chromites are hosted in orthopyroxene-amphibole peridotites. Compositional zonation in chromites is evident with decreasing Cr and Fe content from core to rim, while Al and Mg increase. Homogeneous chromites from another locality are fairly uniform and Fe-rich. The mineral chemistry of the major and accessory phases shows metamorphic signatures. Inferred temperature conditions suggest that the zoned chromites, homogeneous chromites, and their hosts are equilibrated at different metamorphic conditions. In this paper, various mechanisms during the cumulus to subsolidus stages are explored in order to understand the origin of the two contrasting types of chromites.
DS201905-1064
2019
Pearson, G.Nishio, I., Morishita, T., Szilas, K., Pearson, G., Tani, K-I., Tamura, A., Harigane, Y., Guotana, J.M.Titanium clinohumite bearing peridotite from the Ulamertoq ultramafic body in the 3.0 Ga Akia terrane of southern west Greenland.Geosciences ( MDPI), 20p. Europe, Greenlandperidotite

Abstract: A titanian clinohumite-bearing dunite was recently found in the Ulamertoq ultramafic body within the 3.0 Ga Akia Terrane of southern West Greenland. Titanian clinohumite occurs as disseminated and discrete grains. Titanian clinohumite contains relatively high amounts of fluorine, reaching up to 2.4 wt.%. The high-Fo content of olivine (Fo93) coupled with low Cr/(Cr + Al) ratio of orthopyroxene implies that the dunite host is not of residual origin after melt extraction by partial melting of the primitive mantle. Olivine grains are classified into two types based on abundances of opaque mineral inclusions: (1) dusty inclusion-rich and (2) clear inclusion-free olivines. Opaque inclusions in coarse-grained olivines are mainly magnetite. Small amounts of ilmenite are also present around titanian clinohumite grains. The observed mineral association indicates partial replacement of titanian clinohumite to ilmenite (+magnetite) and olivine following the reaction: titanian clinohumite = ilmenite + olivine + hydrous fluid. The coexistence of F-bearing titanian clinohumite, olivine, and chromian chlorite indicates equilibration at around 800-900 °C under garnet-free conditions (<2 GPa). Petrological and mineralogical characteristics of the studied titanian clinohumite-bearing dunite are comparable to deserpentinized peridotites derived from former serpentinites. This study demonstrates the importance of considering the effects of hydration/dehydration processes for the origin of ultramafic bodies found in polymetamorphic Archaean terranes.
DS201907-1558
2019
Pearson, G.Liu, J., Cai, R., Pearson, G., Scott, J.M.Thinning and destruction of the lithospheric mantle root beneath the North China craton: a review.Earth Science Reviews, doi:10.1016/j.earscirev.2019.05.017 19p. Chinacraton

Abstract: It is widely accepted that the lithosphere beneath the eastern portion of the North China Craton (NCC) has suffered extensive thinning and destruction since the Mesozoic. The driving force for this transformation remains debated, although most models make a first-order link with the evolution of the Paleo-Pacific subduction and the effects of the Pacific slab subduction. In this review, we discuss the temporal and spatial relationships between the Paleo-Pacific and the Pacific slab subduction and the lithospheric thinning/destruction processes experienced by the NCC. We recognize four key stages: 1) an initial stage of low angle flat subduction of the Paleo-Pacific slab between ~170-145?Ma, 2) the sinking or rollback of the Paleo-Pacific slab and associated asthenosphere upwelling (145-110?Ma), 3) the disappearance of the Paleo-Pacific slab into lower mantle (110-55?Ma), and 4) the initiation of subduction of the present-day Pacific slab and associated formation of a Big Mantle Wedge (BMW) beneath East Asia (<55?Ma). The initial flat subduction of the Paleo-Pacific plate inhibited mantle-derived magmatism in the period between 170 and 145?Ma beneath the NCC. However, during this stage, intraplate deformation and crustal magmatism migrated westward from craton margin to interior. The cratonic subcontinental lithospheric mantle (SCLM) was further hydrated and metasomatized in addition to that caused by prior circum-cratonic orogenies/subductions. At ca. 155?Ma, the Paleo-Pacific plate began to sink or roll back, causing asthenosphere upwelling and triggering melting of the metasomatized SCLM to form arc-like basalts and low degree melts such as lamprophyres. Vigorous mantle flow/convection transported the metasomatically refertilized and weakened cratonic SCLM into the deep mantle and resulted in the thinning of the lithosphere. At the craton margins, where the lithosphere, thickened by collision, had lost a lower portion of the cratonic SCLM by mantle erosion, delamination of the eclogitic lower crust and underlying pre-thinned SCLM occurred. Upwelling asthenosphere replaced the detached lithosphere and then cooled by conduction to form new lithospheric mantle. This process may have continued to ca. 125?Ma when mantle-derived melts transitioned from arc-like to OIB-like basalts. Replacement of the mantle lithosphere by asthenosphere elevated the lithospheric geotherm and led to extensive crustal melting and the generation of massive volumes of felsic-intermediate magmatism in the eastern NCC until ~110?Ma. After the termination of lithosphere replacement, the speed of subduction of the Paleo-Pacific plate may have increased and by ca. 55?Ma, the whole slab vanished into the lower mantle. We suggest that the subsequent formation of present-day Pacific ocean lithosphere led to a new phase of low angle subduction of the Pacific plate margin. At ca. 35?Ma, the Pacific plate started to descend forming a BMW, accompanied by upwelling of asthenosphere and widespread eruption of alkali basalts across eastern China. The ongoing subduction of the Pacific plate may also lead to further lithospheric thinning.
DS201908-1815
2019
Pearson, G.Shu, Q, Brey, G.P., Pearson, G., Liu, J., Gibson, S.A., Becker, H.The evolution of the Kaapvaal craton: a multi-isotopic perspective from lithospheric peridotites from Finsch diamond mine.Precambrian Research, 105380, 21p. PdfAfrica, South Africadeposit - Finsch

Abstract: Accurately dating the formation and modification of Earth’s sub-cratonic mantle still faces many challenges, primarily due to the long and complex history of depletion and subsequent metasomatism of this reservoir. In an attempt to improve this, we carried out the first study on peridotites from the Kaapvaal craton (Finsch Mine) that integrates results from Re-Os, Lu-Hf, Sm-Nd and Sr-isotope systems together with analyses of major-, trace- and platinum-group elements. The Finsch peridotites are well-suited for such a study because certain compositional features reflect they were highly depleted residues of shallow melting (1.5?GPa) at ambient Archean mantle temperatures. Yet, many of them have overabundant orthopyroxene, garnet and clinopyroxene compared to expected modal amounts for residues from partial melting. Finsch peridotites exhibit a wide range of rhenium depletion ages (TRD) from present day to 2.7?Ga, with a prominent mode at 2.5?Ga. This age overlaps well with a Lu-Hf isochron of 2.64?Ga (?Hf (t)?=?+26) which records silico-carbonatitic metasomatism of the refractory residues. This late Archean metasomatism is manifested by positive correlations of Pt/Ir and Pd/Ir with 187Os/188Os ratios and good correlations of modal amounts of silicates, especially garnet, with Os isotope ratios. These correlations suggest that the Highly Siderophile Elements (HSE) and incompatible element reenrichment and modal metasomatism result from one single major metasomatic event at late Archean. Our detailed study of Finsch peridotites highlights the importance of using multiple isotopic systems, to constrain the ages of events defining the evolution of lithospheric mantle. The Re-Os isotope system is very effective in documenting the presence of Archean lithosphere, but only the oldest TRD ages may accurately date or closely approach the age of the last major partial melting event. For a meaningful interpretation of the Re-Os isotope systematics the data must be combined with HSE patterns, trace-element compositions and ideally other isotopic systems, e.g. Lu-Hf. This is highlighted by the widespread evidence in Finsch peridotites of Pt, Pd and Re enrichment through significant Base Metal Sulfide (BMS) addition (mainly in the range of 0.002-0.08?wt%) that systematically shifts the mode of TRD model ages to younger ages.
DS201910-2260
2019
Pearson, G.Graf, C., Sandner, T., Woodland, A., Hofer, H., Seitz, H-M., Pearson, G., Kjarsgaard, B.Metasomatism, oxidation state of the mantle beneath the Rae craton, Canada.Goldschmidt2019, 1p. AbstractCanadacraton

Abstract: The Rae craton is an important part of the Canadian Shield and was amalgamated to the Slave craton at ?? 1.9 Ga [1]. Recent geophysical and geochemical data indicate a protracted geodynamic history [1, 2]. Even though the oxidation state of the Earth’s mantle has an important influence of fluid compositions and melting behavior, no data on the oxidation state of the Rae’s mantle are available. The aims of this study were to 1) determine the oxidation state (ƒO2) of the lithosphere beneath the Rae craton, 2) link these results to potential metasomatic overprints and 3) compare the geochemical evolution with the Slave craton. We studied 5 peridotite xenoliths from Pelly Bay (central craton) and 22 peridotites from Somerset Island (craton margin). Pelly Bay peridotites give T < 905°C and depths of ??80- 130 km. Garnets have depleted or “normal” REE patterns, the latter samples recording fO2 values ??0.5 log units higher. The deeper samples are more enriched and oxidised. Peridotites from Somerset Island record T ??825-1190°C, a ?logfO2 ranging from ?? FMQ - FMQ-3.6 from a depth interval of ??100-150 km. Garnets exhibit two REE signatures - sinusoidal and “normal” - indicating an evolutionary sequence of increasing metasomatic re-enrichment and a shift from fluid to melt dominated metasomatism. Compared to the Slave craton, the Rae mantle is more reduced at ??80km but becomes up to 2 log units more oxidised (up to ??FMQ-1) at ??100-130 km. Similar oxidising conditions can be found >140 km in the Slave mantle [3]. Especially under Somerset Island, the lithospheric mantle has contrasting fO2 and metasomatic overprints in the same depth range, which may represent juxtaposed old and rejuvenated domains [2].
DS201911-2563
2019
Pearson, G.Smit, K.V., Walter, M.J., Pearson, G., Aulbach, S.Diamonds and the mantle geodynamics of carbon.Researchgate, Chapter 5, pp. 89-128. pdfMantlemineralogy

Abstract: he science of studying diamond inclusions for understanding Earth history has developed significantly over the past decades, with new instrumentation and techniques applied to diamond sample archives revealing the stories contained within diamond inclusions. This chapter reviews what diamonds can tell us about the deep carbon cycle over the course of Earth’s history. It reviews how the geochemistry of diamonds and their inclusions inform us about the deep carbon cycle, the origin of the diamonds in Earth’s mantle, and the evolution of diamonds through time.
DS201912-2775
2019
Pearson, G.Czas, J., Pearson, G., Stachel, T., Kjarsgaard, B.A., Read, G.A Paleoproterozic diamond bearing lithospheric mantle root beneath the Archean Sask Craton.Lithos, 10.1016/j.lithos.2019.105301 63p. PdfCanada, Saskatchewancraton

Abstract: The recently recognised Sask Craton, a small terrane with Archean (3.3-2.5 Ga) crustal ages, is enclosed in the Paleoproterozoic (1.9-1.8 Ga) Trans Hudson Orogen (THO). Only limited research has been conducted on this craton, yet it hosts major diamond deposits within the Cretaceous (~106 to ~95 Ma) Fort à la Corne (FALC) Kimberlite Field. This study describes major, trace and platinum group element data, as well as osmium isotopic data from peridotitic mantle xenoliths (n = 26) from the Star and Orion South kimberlites. The garnet-bearing lithospheric mantle is dominated by moderately depleted lherzolite. Equilibration pressures and temperatures (2.7 to 5.5 GPa and 840 to 1250 °C) for these garnet peridotites define a cool geotherm indicative of a 210 km thick lithosphere, similar to other cratons worldwide. Many of the peridotite xenoliths show the major and trace element signatures of carbonatitic and kimberlitic melt metasomatism. The Re-Os isotopic data yield TRD (time of Re-depletion) model ages, which provide minimum estimates for the timing of melt depletion, ranging from 2.4 to 0.3 Ga, with a main mode spanning from 2.4 to 1.7 Ga. No Archean ages were recorded. This finding and the complex nature of events affecting this terrane from the Archean through the Palaeoproterozoic provide evidence that the majority of the lithospheric mantle was depleted and stabilised in the Palaeoproterozoic, significantly later than the Archean crust. The timing of the dominant lithosphere formation is linked to rifting (~2.2 Ga - 2.0 Ga), and subsequent collision (1.9-1.8 Ga) of the Superior and Hearne craton during the Wilson cycle of the Trans Hudson Orogen.
DS202002-0202
2020
Pearson, G.Lawley, C.J.M., Pearson, G., Waterton, P., Zagorevski, A., Bedard, J.H., Jackson, S.E., Petts, D.C., Kjarsgaard, B.A., Zhang, S., Wright, D.Element and isotopic signature of re-fertilized mantle peridotite as determined by nanopower and olivine LA-ICPMS analyses.Chemical Geology, DOI:101016/ j.chemgeo.2020.119464Mantleperidotite

Abstract: The lithospheric mantle should be depleted in base- and precious-metals as these elements are transferred to the crust during partial melting. However, some melt-depleted mantle peridotites are enriched in these ore-forming elements. This may reflect re-fertilization of the mantle lithosphere and/or sequestering of these elements by residual mantle phase(s). Both processes remain poorly understood because of the low abundances of incompatible elements in peridotite and the nugget-like distribution of digestion-resistant mantle phases that pose analytical challenges for conventional geochemical methods. Herein we report new major and trace element concentrations for a suite of mantle peridotite and pyroxenite samples from the Late Permian to Middle Triassic Nahlin ophiolite (Cache Creek terrane, British Columbia, Canada) using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS) analysis of nanoparticulate powders and olivine. Compatible to moderately incompatible element concentrations suggest that Nahlin ophiolite peridotites represent residues after ?20% melt extraction. Pyroxenite dykes and replacive dunite bands are folded and closely intercalated with residual harzburgite. These field relationships, coupled with the presence of intergranular base metal sulphide, clinopyroxene and Cr-spinel at the microscale, point to percolating melts that variably re-fertilized melt-depleted mantle peridotite. Radiogenic Pb (206Pb/204Pb?=?15.402-19.050; 207Pb/204Pb?=?15.127-15.633; 208Pb/204Pb?=?34.980-38.434; n?=?45) and Os (187Os/188Os 0.1143-0.5745; n?=?58) isotope compositions for a subset of melt-depleted peridotite samples further support metasomatic re-fertilization of these elements. Other ore-forming elements are also implicated in these metasomatic reactions because some melt-depleted peridotite samples are enriched relative to the primitive mantle, opposite to their expected behaviour during partial melting. New LA-ICPMS analysis of fresh olivine further demonstrates that a significant proportion of the highly incompatible element budget for the most melt-depleted rocks is either hosted by, and/or occurs as trapped inclusions within, the olivine-rich residues. Trapped phases from past melting and/or re-fertilization events are the preferred explanation for unradiogenic Pb isotope compositions and Paleozoic to Paleoproterozoic Re-depletion model ages, which predate the Nahlin ophiolite by over one billion years.
DS202011-2059
2020
Pearson, G.Pearson, G.Diamonds found with gold in Canada's Far North offer clues to Earth's early history: discovery of diamonds in small rock sample hints at possibility of new deposits in area similar to world's richest gold mine in South Africa.www.sciencedaily.com/releases/2020/10/201006153459.htm>., Oct. 6, 3p. Canada, Nunavutdiamond genesis

Abstract: The presence of diamonds in an outcrop atop an unrealized gold deposit in Canada's Far North mirrors the association found above the world's richest gold mine, according to University of Alberta research that fills in blanks about the thermal conditions of Earth's crust three billion years ago.
DS202104-0580
2019
Pearson, G.Grass, C., Woodland, A., Hoferm H,m Seitz, H-M., Pearson, G., Kjarsgaard, B.Metasomatism and oxidation state of the lithospheric mantle beneath the Rae Craton, Canada as revealed by xenoliths from Somerset Island and Pelly Bay. ***note dateGeophysical Research abstracts, EGU, EGU2019-9348, 1p. PdfCanadageodynamics

Abstract: We present the first oxidation state measurements for the subcontinental lithospheric mantle (SCLM) beneath the Rae craton, northern Canada, one of the largest components of the Canadian shield. In combination with major and trace element compositions for garnet and clinopyroxene, we assess the relationship between oxidation state and metasomatic overprinting. The sample suite comprises peridotite xenoliths from the central part (Pelly Bay) and the craton margin (Somerset Island) providing insights into lateral and vertical variations in lithospheric character. Our suite contains spinel, garnet-spinel and garnet peridotites, with most samples originating from 100 to 140 km depth. Within this narrow depth range we observe strong chemical gradients, including variations in oxygen fugacity (ƒO2) of over 4 log units. Both Pelly Bay and Somerset Island peridotites reveal a change in metasomatic type with depth. Observed geochemical systematics and textural evidence support the notion that Rae SCLM developed through amalgamation of different local domains, establishing chemical gradients from the start. These gradients were subsequently modified by migrating melts that drove further development of different types of metasomatic overprinting and variable oxidation at a range of length scales. This oxidation already apparent at ~?100 km depth could have locally destabilised any pre-existing diamond or graphite.
DS202104-0599
2021
Pearson, G.Pearson, G.Exploring for diamonds and what they tell us about how the Earth works. *** April 29Carnegie Institute Lecture April 29, 6.30 pm est, Please click this URL to join.Globaldiamond genesis

Abstract: Finding and evaluating diamond deposits is one of the hardest tasks in mineral resource development. In this talk, we will delve a little into the techniques used to find diamonds and how to evaluate the deposits. We will then examine why diamonds-the deepest derived of all natural materials—are unique in their ability to illuminate processes taking place over 700 km beneath Earth's surface, and up to 3.5 billion years back into its history. Click to register for Upcoming April 29, 2021 Webinar.
DS202107-1100
2019
Pearson, G.Graf, C., Woodland, A., Hofer, H., Seitz, H-M., Pearson, G., Kjarsgaard, B.Metasomatism and oxidation state of lithospheric mantle beneath the Rae Craton, Canada as revealed by xenoliths from Somerset Island and Pelly Bay. ** Note dateGeophysical Research Abstracts , 1p. PdfCanada, Somerset Island , Nunavutcratons

Abstract: We present the first oxidation state measurements for the subcontinental lithospheric mantle (SCLM) beneath the Rae craton, northern Canada, one of the largest components of the Canadian shield. In combination with major and trace element compositions for garnet and clinopyroxene, we assess the relationship between oxidation state and metasomatic overprinting. The sample suite comprises peridotite xenoliths from the central part (Pelly Bay) and the craton margin (Somerset Island) providing insights into lateral and vertical variations in lithospheric character. Our suite contains spinel, garnet-spinel and garnet peridotites, with most samples originating from 100 to 140 km depth. Within this narrow depth range we observe strong chemical gradients, including variations in oxygen fugacity (ƒO2) of over 4 log units. Both Pelly Bay and Somerset Island peridotites reveal a change in metasomatic type with depth. Observed geochemical systematics and textural evidence support the notion that Rae SCLM developed through amalgamation of different local domains, establishing chemical gradients from the start. These gradients were subsequently modified by migrating melts that drove further development of different types of metasomatic overprinting and variable oxidation at a range of length scales. This oxidation already apparent at ~?100 km depth could have locally destabilised any pre-existing diamond or graphite.
DS202110-1627
2021
Pearson, G.McIntyre, T., Kublik, K., Currie, C., Pearson, G.Heat generation in cratonic mantle roots - new trace element constraints from mantle xenoliths. And implications for cratonic geotherms.Geochemistry, Geophysics, Geosystems, 10.1029/2021GC009691 55p. PdfAfrica, South Africa, Lesotho, Europe, Greenlandcraton

Abstract: Understanding the rate at which temperature changes with increasing depth (geothermal gradients) within ancient continental crust and its underlying mantle (cratonic lithosphere) is essential for understanding the internal structure of Earth. However, understanding geothermal gradients requires a chemical and physical understanding of deep cratonic lithosphere (up to ?200 km depth) and samples from such depths are only available as fragments hosted in melts that originate there (e.g., kimberlites). This limited sample availability of the cratonic mantle roots has resulted in some properties of this domain, used in geothermal modeling, to be poorly constrained. Here we use samples of cratonic mantle lithosphere to determine one critical and poorly constrained parameter used in modeling geothermal gradients—the heat produced from the radiogenic decay of K, U, and Th to their daughter isotopes. We measure these elements in the samples via in situ laser ablation methods to quantify their potential heat production. Comparing our results to previous estimates of heat production, our new estimates produce differences in the thicknesses of cratonic lithosphere calculated from modeled geothermal gradients by >10 km depending on the chosen lithological model. The results from this study provide an important new data set for constraining heat production in cratonic mantle peridotites.
DS202201-0016
2021
Pearson, G.Grutter, H., Stachel, T., Sarkar, C., Pearson, G.Profound ~ 1075 Ma (re)fertilization of the central Superior craton lithosphere, based on composition and Pb-isotope data for clinopyroxenes from the Victor mine, Ontario, Canada.GAC/MAC Meeting UWO, 1p. Abstract p.117.Canada, Ontariodeposit - Victor

Abstract: The Victor diamond mine in Ontario, Canada opened in 2008 and ceased operations in June 2019. Previous researchers documented that Victor diamonds are unusually young (~ 720 Ma, Aulbach et al., 2018) and grew predominantly in unusually fertile peridotite substrates, specifically garnet lherzolite and garnet wehrlite (Stachel et al., 2018). Our recent work on n=157 lherzolitic clinopyroxene (Cpx) xenocrysts from the Victor mine reveals profound major- and trace-element (re)fertilization of the deepest 1/3rd of the central Superior craton lithosphere. For example, Cpx Mg/(Mg+Fe) of 0.93 in shallow peridotite decreases across a steep gradient to Mg/(Mg+Fe) of 0.89 at depths of 4.2 to 5.6 GPa. We document marked compositional gradients over a similar depth range for certain minor (Ti, Mn, Ni) and trace elements (LREE and HREE) and attribute the gradients to chromatographic and/or crystal-chemical fractionation effects. We carefully categorized the Victor cpx xenocrysts in nine depth-composition classes and determined Pb-isotope ratios for representative grains from each class in a bold experiment aimed at capturing geochronological data from mantle Cpx. A resultant 207Pb/206Pb secondary isochron array at ~ 1075 Ma identifies craton-scale events related to the Mid-Continent Rift as the source of fluids and/or melts that (re)fertilized the central Superior craton at depth, some 355 Ma prior to diamond growth. Coordinated, systematic major- and trace-element relationships in clinopyroxene permit compositional discrimination of mantle (re)fertilization at ~1075 Ma from fluid-metasomatism attending diamond growth at ~ 720 Ma. Roughly 10% of the clinopyroxene xenocrysts analyzed in this work exhibit diamond-associated compositions.
DS202201-0031
2021
Pearson, G.Pearson, G., Schaeffer, A., Stachel, T., Kjarsgaard, B., Grutter, H., Scott, J., Liu, J., Chacko, T., Smit, K.Revisiting the craton concept and its relevance for diamond exploration. *** See also Nature article previously listedGAC/MAC Meeting UWO, 1p. Abstract p. 238. Globalcratons

Abstract: The term craton has a complex and confused etymology. Despite originally specifying only strength and stability - of the crust - the term craton, within the context of diamond exploration, has widely come to refer to a region characterised by crustal basement older than 2.5 Ga, despite the fact that some such “cratons” no longer possess their deep lithospheric root. This definition often precluded regions with deep lithospheric roots but basement younger than 2-2.5 Ga. Viscous, buoyant lithospheric mantle roots are key to the survival and stability of continental crust. Here we use a revised craton definition (Pearson et al., 2021, in press), that includes the requirement of a deep (~150 km or greater) and intact lithospheric root, to re-examine the link between cratons and diamonds. The revised definition has a nominal requirement for tectonic stability since ~ 1 Ga and recognises that some regions are “modified cratons” - having lost their deep roots, i.e., they may have behaved like cratons for an extended period but subsequently lost much of their stabilising mantle roots during major tectono-thermal events. In other words, despite being long-lived features, cratons are not all permanent. The 150 km lithospheric thickness cut-off provides an optimal match to crustal terranes with 1 Ga timescale stability. In terms of regional diamond exploration, for a given area, the crucial criterion is when a deep mantle root was extant, i.e., over what period was the lithospheric geotherm suitable for diamond formation, stability and sampling? A thick lithospheric root is key to the formation of deep-seated magmas such as olivine lamproites and to the evolution of sub-lithospheric sourced proto-kimberlites, all capable of carrying and preserving diamonds to Earth's surface. This criterion appears essential even for sub-lithospheric diamonds, that still require a diamond transport mechanism capable of preserving the high-pressure carbon polymorph via facilitating rapid transport of volatile-charged magma to the surface, without dilution from additional melting that takes place beneath thinner (<120 km) lithospheric "lids". Seismology can help to define the lateral extent of today's cratons, but a detailed understanding of the regional geological history, kimberlite eruption ages and geothermal conditions is required to evaluate periods of past diamond potential, no-longer evident today. This revised craton concept broadens the target terranes for diamond exploration away from only the Archean cores of cratons and an associated mentality that "the exception proves the rule". The revised definition is compatible with numerous occurrences of diamond in Proterozoic terranes or Archean terranes underpinned by Proterozoic mantle.
DS202201-0047
2021
Pearson, G.Xu, Y., Pearson, G., Harris, G., Kopylova, M., Liu, J.Age and provenance of the lithospheric mantle beneath the Chidliak kimberlite province, southern Baffin Island: implications for the evolution of the North Atlantic craton.GAC/MAC Meeting UWO, 1p. Abstract p. 312.Canada, Baffin Islanddeposit - Chidliak

Abstract: A suite of peridotite xenoliths from the Chidliak kimberlite province provides an ideal opportunity to assess the age of the mantle lithosphere beneath the eastern Hall Peninsula Block (EHPB) in southern Baffin Island, Nunavut and to provide constraints on the lithospheric architecture of this region. The new dataset comprises highly siderophile element (HSE) abundances and Re-Os isotopic compositions for 32 peridotite xenoliths sampled from four Late Jurassic-Early Cretaceous kimberlite pipes (CH-1, -6, -7, and -44). These peridotites represent strongly depleted mantle residues, with bulk-rock and olivine chemistry denoting melt extraction extents of up to 40%. The vast majority of samples show PPGE (Pt and Pd) depletion relative to IPGE (Os, Ir, and Ru) ((Pt/Ir)N: 0.10-0.96, median = 0.57; (Pd/Ir)N: 0.03-0.79, median = 0.24), coupled with mostly unradiogenic Os isotopic compositions (187Os/188Os = 0.1084-0.1170). These peridotites display strong correlations between 187Os/188Os and melt depletion indicators (such as olivine Mg number and bulk-rock Al2O3, (Pd/Ir)N), suggesting that an ancient (~2.8 Ga) melt depletion event governed the formation of the Chidliak lithosphere. The prominent mode of TRDerupt model ages at ca. 2.8 Ga matches the main crust-building ages of the EHPB, demonstrating temporal crust-mantle coupled in the Meso-Neoarchean. These ancient melt-depletion ages are present throughout the depth of the ~ 200 km thick lithospheric mantle column beneath Chidliak. The Meso-Neoarchean formation age of the EHPB mantle broadly coincides with the timing of stabilization of the lithospheric mantle beneath the Greenlandic portion of the North Atlantic Craton (NAC). This, along with the similarity in modal mineralogy, chemical composition and evolutionary history, indicates that the EHPB, southern Baffin Island was once -contiguous with the Greenlandic NAC. The mantle lithosphere beneath both the EHPB and the NAC show a similar metasomatic history, modified by multiple pulses of metasomatism. These multiple metasomatic events combined to weaken and thin the lithospheric mantle, culminating in the formation of the Labrador Sea and Davis Strait separating the EHPB from the Greenlandic NAC in the Paleocene.
DS202202-0197
2022
Pearson, G.Karaevangelou, M., Kopylova, M.G., Luo, Y., Pearson, G., Reutsky, V.N.Mineral inclusions in Lace diamonds and the mantle below the Kroonstad kimberlite cluster in South Africa.Contribution to Mineralogy and Petrology, Vol. 1777, 2, 10.1007/s00410-021-01880-8Africa, South Africadeposit - Lace

Abstract: We studied diamond inclusions in the 133 Ma Lace kimberlite of the Kroonstad Group II kimberlite cluster (Kaapvaal craton) to compare them to diamonds beneath the adjacent coeval Voorspoed kimberlite. The studied 288 Lace diamonds are mostly colorless dodecahedral Type IaAB. Based on diamond inclusions (DI), 38 Lace diamonds were classified as eclogitic (44%, 19 samples), peridotitic (35%, 15 samples), and websteritic (9%, 4 samples). The diamonds formed from mantle carbon (?13C?=?? 9.1 to ? 2.5 ‰ for 18 samples), with the exception of one eclogitic diamond (?13C?=?? 19.2 ‰). A rare zircon inclusion provides age constraints for the Lace eclogite protolith at 3.2?±?0.4 Ga (Lu-Hf model age) and Lace eclogite diamond formation at 188?±?37 Ma (U-Pb age). The eclogite protolith age suggests its formation contemporaneous with the lower crustal magmatism and metamorphism in the Central Kaapvaal craton, complementary to the tonalite-trondhjemite-granodiorite magmatism in the region and synchronous with the consolidation of the Eastern Kaapvaal Block. Two distinct kinds of eclogites are found to host Lace diamonds, (1) Fe-rich eclogites located at 160-190 km, and (2) more calcic-magnesian eclogites with mineral compositions identical to websteritic DIs, that derive from shallower lithospheric depths. Various thermobarometric methods applied to Lace diamonds and DIs constrain the Lace geotherm as reflecting a surface heat flow below or equal to 38 mW/m2 and a lithosphere thickness of at least 220 km, at the time of kimberlite eruption. These thermal parameters demonstrate an excellent match between the thermal state of the Voorspoed and Lace mantle segments that persisted from the Archean to Cretaceous times. The Lace peridotitic-to-eclogitic diamond ratio (5/4) does not differ much from the Voorspoed DI ratio (6/4), but a hot and spatially restricted carbonatitic metasomatism event affected the Voorspoed peridotitic mantle to create the majority of Voorspoed diamonds. The contrast in the mineralogy of DIs in Lace and Voorspoed diamonds highlights the very local (ca. 10 km) extent of the metasomatism and heating, as well as the variability of the diamond-forming processes at the same spatial scale.
DS202204-0515
2022
Pearson, G.Barrett, N., Jaques, A.L., Gonzalez-Alvarez, I., Walter, M.J., Pearson, G.Ultra-refractory peridotites of Phanerozoic mantle origin: the Papua New Guinea ophiolite mantle tectonites. ( harzburgites and peridotites)Journal of Petrology, 10.1093/petrology/egac014Asia, Papua New Guineaperidotites

Abstract: Harzburgites and dunites forming the base of the Late Cretaceous-Paleocene Papuan Ultramafic Belt (PUB) and Marum ophiolites of Papua New Guinea (PNG) are amongst the most refractory mantle peridotites on Earth. We present a new integrated dataset of major element, bulk plus mineral trace element and Re-Os isotopic analyses aimed at better understanding the genesis of these peridotites. The PUB harzburgites contain olivine (Fo92-93), low-Al enstatite (less than or equal to 0.5 wt. % Al2O3 and CaO), and Cr-rich spinel (Cr# = 0.90-0.95). The Marum harzburgites are less refractory with olivine (Fo91.9-92.7), enstatite (~0.5-1.0 wt. % Al2O3 and CaO), minor clinopyroxene (diopside), and spinel (Cr# = 0.71-0.77). These major element characteristics reflect equivalent or greater levels of melt depletion than that experienced by Archean cratonic peridotites. Whereas bulk-rock heavy rare earth element (HREE) abundances mirror the refractory character indicated by the mineral chemistry and major elements, large-ion lithophile elements (LILEs) indicate a more complex melting and metasomatic history. In-situ olivine and orthopyroxene REE measurements show that harzburgites and dunites have experienced distinct melt-rock interaction processes, with dunite channels/lenses, specifically, showing higher abundances of HREE in olivine. Distinctive severe inter-element fraction of platinum group elements and Re result in complex patterns that we refer to as “M-shaped”. These fractionated highly siderophile element (HSE) patterns likely reflect the dissolution of HSE-rich phases in highly depleted peridotites by interaction with subduction-related melts/fluids, possibly high-temperature boninites. Osmium isotope compositions of the PNG peridotites are variable (187Os/188Os = 0.1204 to 0.1611), but fall within the range of peridotites derived from Phanerozoic oceanic mantle, providing no support for ancient melt depletion, despite their refractory character. This provides further evidence that highly depleted peridotites can be produced in the modern Earth, in subduction zone environments. The complex geochemistry indicates a multi-stage process for the formation of the PNG mantle peridotites in a modern geodynamic environment. The first stage involves partial melting at low-pressure (<2 GPa) and high-temperature (~1250-1350 0C) to form low-K, low-Ti tholeiitic magmas that formed the overlying cumulate peridotite-gabbro and basalt (PUB only) sequences of the ophiolites. This is inferred to have occurred in a fore-arc setting at the initiation of subduction. Later stages involved fluxing of the residual harzburgites with hydrous fluids and melts to form replacive dunites and enstatite dykes, and interaction of the residual peridotites in the overlying mantle wedge with high-temperature hydrous melts from the subducting slab to generate the extremely refractory harzburgites. This latter stage can be linked to the eruption of low-Ca boninites at Cape Vogel, and other arc-related volcanics, in a nascent oceanic island arc. Both ophiolites were emplaced shortly after when the embryonic oceanic island arc collided with the Australian continent.
DS202205-0673
2022
Pearson, G.Barrett, N., Jaques, A.L., Gonzalqez-Alvarez, I., Walter, M.J., Pearson, G.Ultra-refractory peridotites of Phanerozoic mantle origin: the Papua New Guinea ophiolite mantle tectonites.Journal of Petrology, 10.1093/petrology/egac014 99p. pdf Asia, Papua New Guineatectonites

Abstract: Harzburgites and dunites forming the base of the Late Cretaceous-Paleocene Papuan Ultramafic Belt (PUB) and Marum ophiolites of Papua New Guinea (PNG) are among the most refractory mantle peridotites on Earth. We present a new integrated dataset of major element, bulk plus mineral trace element and Re-Os isotopic analyses aimed at better understanding the genesis of these peridotites. The PUB harzburgites contain olivine (Fo92-93), low-Al enstatite (less than or equal to 0.5 wt. % Al2O3 and CaO), and Cr-rich spinel (Cr#?=?0.90-0.95). The Marum harzburgites are less refractory with olivine (Fo91.9-92.7), enstatite (~0.5-1.0 wt. % Al2O3 and CaO), minor clinopyroxene (diopside), and spinel (Cr#?=?0.71-0.77). These major element characteristics reflect equivalent or greater levels of melt depletion than that experienced by Archean cratonic peridotites. Whereas bulk-rock heavy rare earth element (HREE) abundances mirror the refractory character indicated by the mineral chemistry and major elements, large-ion lithophile elements indicate a more complex melting and metasomatic history. In situ olivine and orthopyroxene REE measurements show that harzburgites and dunites have experienced distinct melt-rock interaction processes, with dunite channels/lenses, specifically, showing higher abundances of HREE in olivine. Distinctive severe inter-element fraction of platinum group elements and Re result in complex patterns that we refer to as ‘M-shaped’. These fractionated highly siderophile element (HSE) patterns likely reflect the dissolution of HSE-rich phases in highly depleted peridotites by interaction with subduction-related melts/fluids, possibly high-temperature boninites. Osmium isotope compositions of the PNG peridotites are variable (187Os/188Os?=?0.1204 to 0.1611), but fall within the range of peridotites derived from Phanerozoic oceanic mantle, providing no support for ancient melt depletion, despite their refractory character. This provides further evidence that highly depleted peridotites can be produced in the modern Earth, in subduction zone environments. The complex geochemistry indicates a multi-stage process for the formation of the PNG mantle peridotites in a modern geodynamic environment. The first stage involves partial melting at low-pressure (<2 GPa) and high-temperature (~1250°C-1350°C) to form low-K, low-Ti tholeiitic magmas that formed the overlying cumulate peridotite-gabbro and basalt (PUB only) sequences of the ophiolites. This is inferred to have occurred in a fore-arc setting at the initiation of subduction. Later stages involved fluxing of the residual harzburgites with hydrous fluids and melts to form replacive dunites and enstatite dykes and interaction of the residual peridotites in the overlying mantle wedge with high-temperature hydrous melts from the subducting slab to generate the extremely refractory harzburgites. This latter stage can be linked to the eruption of low-Ca boninites at Cape Vogel, and other arc-related volcanics, in a nascent oceanic island arc. Both ophiolites were emplaced shortly after when the embryonic oceanic island arc collided with the Australian continent.
DS202205-0726
2022
Pearson, G.Veglio, C., Lawley, C.J.M., Kjarsgaard, B., Petts, D., Pearson, G., Jackson, S.E.Olivine xenocrysts reveal carbonated mid-lithosphere in the northern Slave craton.Lithos, 10.1016/j.lithos.2022.106633, 14p. PdfCanada, Northwest Territoriesolivine

Abstract: The cold, rigid, and melt-depleted mantle underlying Archean cratons plays an important role in the preservation of the overlying continental crust and is one of the main sources of diamonds. However, with the possible exception of rare earth elements (REE) and platinum group-elements (PGE), the concentrations and host mineral phases for many other critical trace elements within lithospheric mantle remain very poorly understood. Here we address that knowledge gap, presenting new electron microprobe and laser-ablation inductively-coupled-plasma mass-spectrometry results for a suite of mantle xenoliths (n = 12) and olivine xenocrysts (n = 376) from the Jericho, Muskox, and Voyageur kimberlites (northern Slave craton, Canada). Low-temperature (<1000 °C) harzburgite xenoliths and olivine xenocrysts suggest that the shallowest portions of the garnet-bearing mantle (?160 km) underlying the northern Slave craton is chemically depleted and becomes increasing re-fertilized from 160 to 200 km. High-temperature (>1000 °C) garnet and clinopyroxene crystals with Ti/Eu ratios > > 1000, and olivine xenocrysts suggest that interaction with ultramafic silicate melts is the most likely mechanism to re-fertilize melt-depleted peridotite with incompatible elements toward the base of the lithosphere (~200 km). In contrast, lower temperature garnet and clinopyroxene with Ti/Eu ratios <1000 are more likely related to metasomatism by carbonatitic melts and/or fluids. Carbonatitic metasomatism is also interpreted as the preferred explanation for the trend of Nb (4 ppm)- and Ta (185 ppb)-rich concentrations of olivine xenocrysts sampled from mid-lithosphere depths (~140 km). With the exception of a few elements that substitute into the olivine crystal structure during sub-solidus re-equilibration (e.g., Ca, Cr, Cu, Na, Sc, V, Zn), most other olivine-hosted trace elements do not systematically vary with depth. Instead, we interpret olivine-hosted trace element concentrations that are significantly above the analytical detection and/or quantification limits to reflect trapped fluid (e.g., As, Mo, Sb, Sn), base-metal sulphide (e.g., Ag, Au, Bi, Pd, Pt, Se, Te), and other mineral inclusions (e.g., U, Th) rather than enrichments of these elements due to substitution reactions or analytical artefacts. We interpret that these inclusions occur in olivine throughout the garnet stability field, but are relatively rare. As a result, these trapped carbonatitic, proto-kimberlite, and/or other ultramafic silicate melts do not represent a significant source for the suite of trace elements that become enriched to economic levels in the crust.
DS200612-0945
2006
Pearson, G.D.Morel, M.L.A., Simon, N.S.C., Davies, G.F., Pearson, G.D.Modification of cratonic lithosphere: influence of tectono magmatic events on Kaapvaal craton ( South Africa).Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 428. abstract only.Africa, South AfricaMagmatism, tectonics
DS200612-1178
2006
Pearson, G.D.Rosenthal, A., Foley, S.F., Pearson, G.D., Nowell, G., Tappe, S.Ugand an kamafugites: re-melting of a variable enriched veined subcontinental lithospheric mantle.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 26, abstract only.Africa, UgandaGeochemistry - melting
DS201712-2668
2017
Pearson, G.D.Agrosi, G., Tempesta, G., Mele, D., Allegretta, I., Terzano, R., Shirery, S.B., Pearson, G.D., Nestola, F.Non-destructive, multi-method, internal analysis of multiple inclusions in a single diamond: first occurrence of mackinawite ( Fe,Ni)1+xSAmerican Mineralogist, Vol. 102, pp. 2235-2243.Russia, Siberiadeposit - Udachnaya

Abstract: A single gem lithospheric diamond with five sulfide inclusions from the Udachnaya kimberlite (Siberia, Russia) has been analyzed non-destructively to track the growth conditions of the diamond. Sulfides are the most abundant mineral inclusions in many lithospheric diamond crystals and are the most favorable minerals to date diamond crystals by Re-Os isotope systematics. Our investigation used non-destructive, micro-techniques, combining X-ray tomography, X-ray fluorescence, X-ray powder diffraction, and Raman spectroscopy. This approach allowed us to determine the spatial distribution of the inclusions, their chemical and mineralogical composition on the microscale, and, finally, the paragenetic association, leaving the diamond host completely unaffected. The sample was also studied by X-ray diffraction topography to characterize the structural defects of the diamond and to obtain genetic information about its growth history. The X-ray topographic images show that the sample investigated exhibits plastic deformation. One set of {111} slip lamellae, corresponding to polysynthetic twinning, affects the entire sample. Chemical data on the inclusions still trapped within the diamond show they are monosulfide solid solutions of Fe, Ni and indicate a peridotitic paragenesis. Micro-X-ray diffraction reveals that the inclusions mainly consist of a polycrystalline aggregate of pentlandite and pyrrothite. A thorough analysis of the Raman data suggests the presence of a further Fe, Ni sulfide, never reported so far in diamonds: mackinawite. The total absence of any oxides in the sulfide assemblage clearly indicates that mackinawite is not simply a “late” alteration of pyrrhotite and pentlandite due to secondary oxidizing fluids entering diamond fractures after the diamond transport to the surface. Instead, it is likely formed as a low-temperature phase that grew in a closed system within the diamond host. It is possible that mackinawite is a more common phase in sulfide assemblages within diamond crystals than has previously been presumed, and that the percentage of mackinawite within a given sulfide assemblage could vary from diamond to diamond and from locality to locality.
DS202105-0782
2021
Pearson, G.D.Pearson, G.D.Exploring for diamonds and what they tell us about how the Earth works. April 29Carnegiescience.edu, https://youtu.be /23M235RKAqA Globaldiamond genesis

Abstract: Finding and evaluating diamond deposits is one of the hardest tasks in mineral resource development. In this talk, we will delve a little into the techniques used to find diamonds and how to evaluate the deposits. We will then examine why diamonds-the deepest derived of all natural materials-are unique in their ability to illuminate processes taking place over 700 km beneath Earth's surface, and up to 3.5 billion years back into its history.
DS1920-0293
1926
Pearson, H.Pearson, H.The Diamond Trail. an Account of Travel Among the Little Known Bahian Diamond Fields of Brasil.London: H.f. And G. Witherby, 230P.BrazilTravelogue
DS1995-1463
1995
Pearson, J.Pearson, J.Geology of the Mesoproterozoic Gifford Creek alkaline igneous complex, Gascoyne Province, Western Australia.University of West. Australian Key Centre, held Feb. 15, 16th., 12p.AustraliaAlkaline rocks, Gifford Creek complex
DS201012-0263
2010
Pearson, J.Halpin, K., Ansdell, K., Pearson, J.The characteristics and origin of Great Western Minerals Group Ltd.'s Hoidas Lake REE deposit, Rae province, Northwestern Saskatchewan.International Workshop Geology of Rare Metals, held Nov9-10, Victoria BC, Open file 2010-10, extended abstract pp.45.Canada, SaskatchewanAlkalic
DS200412-1510
2004
Pearson, J.G.Pearson, J.G., Nowell, G.M.Re Os and Lu Hf isotope constraints on the origin and age of pyroxenites from the Beni Bousera peridotite massif: implications fJournal of Petrology, Vol. 45, 2, pp. 439-455.Africa, MoroccoGeochronology
DS200912-0490
2009
Pearson, J.G.McNeill, J., Pearson, J.G., Klein Ben-David, O., Nowell, G.M., Ottlet, C.J., Chinn, I.Quantitative analysis of trace element concentration in some gem quality diamonds.Journal of Physics Condensed Matter, in pressSouth America, Venezuela, Russia, Siberia, South AfricaDeposit - Cullinan, Mir, Udachnaya
DS1994-1349
1994
Pearson, J.M.Pearson, J.M., Barley, M.E., Taylor, W.R.Alkaline rocks and fenites of the Proterozoic Gifford Creek Complex, Gascoyne Province, Western Australia.Geological Association of Canada (GAC) Abstract Volume, Vol. 19, p. posterAustraliaAlkaline rocks, Gifford Creek
DS1995-1464
1995
Pearson, J.M.Pearson, J.M.Gascoyne alkaline rocks: mineralization potential, petrogenesis and tectonic significance.Ph.d. Thesis, University of of Western Australia, AustraliaAlkaline rocks, Deposit -Gascoyne area
DS1996-1086
1996
Pearson, J.M.Pearson, J.M., Taylor, W.R.Mineralogy and geochemistry of fenitized alkaline ultrabasic sills of the Gifford Creek Complex, GascoyneCanadian Mineralogist, Vol. 34, pt. 2, April pp. 201-220.Australia, Western AustraliaAlkaline sills
DS1996-1087
1996
Pearson, J.M.Pearson, J.M., Taylor, W.R., Barley, M.E.Geology of the alkaline Gifford Creek Complex, Gascoyne Complex, westernAustralia.Australian Journal of Earth Sciences, Vol. 43, No. 3, June 1, pp. 299-310.AustraliaAlkaline rocks, Gifford Creek Complex
DS1993-0252
1993
Pearson, L.M.Christensen, R., Johnson, W., Pearson, L.M.Covariance function diagnostics for spatial linear modelsMathematical Geology, Vol. 25, No. 2, pp. 145-160GlobalGeostatistics, Kriging
DS2000-0363
2000
Pearson, N.Griffin, W.L., Pearson, N., Bolousova, Van AchterberghThe hafnium isotope composition of cratonic mantle: LAM MC ICPMS analysis of zircon megacrysts in kimberlites.Geochimica et Cosmochimica Acta, Vol. 64, pp. 133-47.AustraliaGeochronology
DS2001-0258
2001
Pearson, N.Djomani, Y.P., Griffin, B., O'Reilly, S., Pearson, N.The Slave Craton ( Canada) in deep analysisGemoc Annual Report 2000, p. 28-9.Northwest TerritoriesGeophysics - gravity, Lithosphere
DS2001-0412
2001
Pearson, N.Griffin, B., Pearson, N., O'Reilly, S.Sorting out the mantle: in situ measurement of Rhenium- Osmium (Re-Os) isotopes in mantle sulphides by LAM MC ICPNSGemoc Annual Report 2000, p. 32-3.FranceGeochronology - lherzolite
DS2003-0869
2003
Pearson, N.Malkovets, V.G., Taylor, L.A., Griffin, W., O'Reilly, S., Pearson, N., PokhilenkoCratonic considitons beneath Arkhangelsk, Russia: garnet peridotites form the Grib8ikc, Www.venuewest.com/8ikc/program.htm, Session 4, POSTER abstractRussia, Kola PeninsulaMantle geochemistry, Deposit - Grib
DS2003-1557
2003
Pearson, N.Zheng, J., Sun, M., Lu,. F., Pearson, N.Mesozoic lower crustal xenoliths and their significance in lithospheric evolution beneathTectonophysics, Vol. 361, No. 1-2, pp. 37-60.ChinaXenoliths
DS200612-1060
2006
Pearson, N.Pearson, N.Isotopic ratio measurement using microbeam methods: where do we stand and where are we going?GEMOC Annual Report, 2005, p. 32-33.MantleGeochronology - laser ablation
DS200612-1605
2006
Pearson, N.Zheng, J., Griffin, W.L., O'Reilly, S.Y., Zhang, M., Pearson, N.Zircons in mantle xenoliths record the Triassic Yangtze North Chin a continental collision.Earth and Planetary Science Letters, in press availableChinaGeochronology, peridotite, North China Craton
DS200612-1606
2006
Pearson, N.Zheng, J., Griffin, W.L., O'Reilly, S.Y., Zhang, M., Pearson, N., Luo, Z.The lithospheric mantle beneath the southeastern Tian Shan area, northwest China.Contributions to Mineralogy and Petrology, Vol. 141, 4, April pp. 457-479.Asia, ChinaPetrology
DS200612-1607
2006
Pearson, N.Zheng, J., Griffin, W.L., O'Reilly, S.Y., Zhang, M., Pearson, N., Pan, Y.Wide spread Archean basement beneath the Yangtze Craton.Geology, Vol. 34, 6, June pp. 417-420.Asia, ChinaGeochronology
DS200712-1239
2007
Pearson, N.Zheng, J.P., Griffin, W.L., O'Reilly, S.Y., Yu, C.M., Zhang, H.F., Pearson, N., Zhang, M.Mechanism and timing of lithospheric modification and replacement beneath the eastern North Chin a Craton: peridotitic xenoliths from the 100 Ma Fuxin basaltsGeochimica et Cosmochimica Acta, In press, availableChinaXenoliths
DS200712-1240
2007
Pearson, N.Zheng, J.P., Griffin, W.L., O'Reilly, S.Y., Yu, C.M., Zhang, H.F., Pearson, N., Zhang, M.Mechanism and timing of lithospheric modification and replacement beneath the eastern North Chin a Craton: peridotitic xenoliths from the 100 Ma Fuxin basalts...Geochimica et Cosmochimica Acta, Vol. 71, 21, pp. 5303-5225.ChinaXenoliths - regional synthesis
DS200912-0859
2009
Pearson, N.Zheng, J., Griffin, W.L., O'Reilly, S.Y., Liu, G.L., Pearson, N., Zhang, W., Yu, C.M., Su, Tang, ZhaoNeoarchean ( 2.7-2.8 Ga) accretion beneath the North Chin a Craton: U Pn age.trace elemens and hf isotopes of zircons in Diamondiferous kimberlites.Lithos, Vol. 112, 3-4, pp. 188-202.ChinaGeochronology
DS200912-0860
2009
Pearson, N.Zheng, J.P., Griffin, W.L., O'Reilly, S.Y., Sun, M., Zheng, S., Pearson, N., Gao, Yu, Su, Tang, Liu, WuAge and composition of granulite and pyroxenite xenoliths in Hannuoba basalts reflect Paleogene underplating beneath the North Chin a craton.Chemical Geology, Vol. 264, 1-4, pp. 266-280.ChinaXenoliths
DS201112-0454
2011
Pearson, N.Howell, D., Griffin, W.L., O'Reilly, S.Y., O'Neill, C., Pearson, N., Piazolo, Stachel, Stern, NasdalaMixed habit diamonds: evidence of a specific mantle fluid chemistry?Goldschmidt Conference 2011, abstract p.1051.TechnologyDiamond morphology, growth
DS1990-1166
1990
Pearson, N.J.Pearson, N.J., O'Reilly, S.Y., Griffin, W.L.The lower crust beneath the eastern margin of the Australian craton:xenolith evidence for the gabbroto eclogite transitionGeological Society of Australia Abstracts, No. 25, No. A12.11 pp. 237. AbstractAustraliaXenolith, Eclogites
DS1991-0264
1991
Pearson, N.j.Chen, Y.D., Pearson, N.j., O'Reilly, S.Y., Griffin, W.L.Applications of olivine: orthopyroxene-spinel oxygen geobarometers to the redox state of the upper mantleProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 42-44Australia, China, South Africa, TanzaniaGeobarometry, Mantle
DS1991-1315
1991
Pearson, N.J.Pearson, N.J., O'Reilly, S.Y.Thermobarometry and P-T-t paths: the granulite to eclogite transition in lower crustal xenoliths from eastern AustraliaJournal of Metamorphic Geology, Vol. 9, No. 3, May pp. 349-359AustraliaEclogites, Geothermobarometry
DS1991-1316
1991
Pearson, N.J.Pearson, N.J., O'Reilly, S.Y., Griffin, W.L.The granulite to eclogite transition beneath the eastern margin of the Australian cratonEuropean Journal of Mineralogy, Vol. 3, No. 2, pp. 293-322AustraliaEclogite, Craton
DS1991-1317
1991
Pearson, N.J.Pearson, N.J., O'Reilly, S.Y., Griffin, W.L.Heterogeneity in the thermal state of the lower crust and upper mantle beneath eastern AustraliaAustralian Society of Exploration Geophysicists and Geological Society of Australia, 8th. Exploration Conference in the Bulletin., Vol. 22, No. 2, June pp. 295-298AustraliaMantle, Geothermometry
DS1992-0246
1992
Pearson, N.J.Chen, Y.D., Pearson, N.J., O'Reilly, S.Y., Griffin, W.L.Application of the olivine-orthopyroxene spinel oxygen geobarometers to redox state of upper mantle11th. Australian Geol. Convention Held Ballarat University College, Jan., Abstract onlyAustraliaMantle, Geobarometry
DS1993-1208
1993
Pearson, N.J.Pearson, N.J., O'Reilly, S.Y., Griffin, W.L.Thermal states of diverse lithospheric sections: lower crustal xenoliths across carton boundaries from South Africa and Australia.The Xenolith window into the lower crust, abstract volume and workshop, p. 16.South Africa, AustraliaKaapvaal craton, Tasman Fold Belt
DS1995-1465
1995
Pearson, N.J.Pearson, N.J., O'Reilly, S.Y., Griffin, W.L.The crust mantle boundary beneath cratons and craton margins: a transect across southwest margin KaapvaalLithos, Vol. 36, No. 3/4, Dec. 1, pp. 257-288.South AfricaCraton -Kaapvaal, Geothermometry
DS1995-1635
1995
Pearson, N.J.Ryan, C.G., Griffin, W.L., Pearson, N.J., Win, T.T.Garnet geotherms: derivation of P-T dat a from chromium-Pyrope garnetsProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 476-478.South Africa, Russia, Siberia, Mongolia, China, Solomon IslandsGeothermometry, Deposit -Kaapvaal area and Dadlyn area
DS1996-1088
1996
Pearson, N.J.Pearson, N.J.Laser ablation ICPMS: applications to diamond explorationGeological Society of Australia 13th. Convention held Feb., No. 41, abstracts p. 338.AustraliaPetrogenesis, Technology -LAM-ICPMS
DS1996-1089
1996
Pearson, N.J.Pearson, N.J., O.Reilly, S.Y., Griffin, W.L.Lower crust geothermsInternational Geological Congress 30th Session Beijing, Abstracts, Vol. 1, p. 119.South AfricaKaapvaal Craton, Geothermometry
DS1998-0108
1998
Pearson, N.J.Belousova, E.A., Griffin, W.L., Pearson, N.J.Trace element composition and cathodluminescence properties of Southern african kimberlitic zircons.Mineralogical Magazine, Vol. 62, No. 3, June pp. 355-66.South AfricaDiamond inclusions, Mineral chemistry
DS1998-0306
1998
Pearson, N.J.Davies, R., Griffin, W.L., Pearson, N.J., Andrew, DoyleDiamonds from the Deep: Pipe DO 27, Slave Craton, Canada7th International Kimberlite Conference Abstract, pp. 170-172.Northwest TerritoriesDiamond inclusions, Deposit - Pipe DO-27
DS1998-1139
1998
Pearson, N.J.Pearson, N.J., Griffin, Kaminsky, Van AchterberghTrace element discrimination of garnet from Diamondiferous kimberlites andlamproites.7th. Kimberlite Conference abstract, pp. 673-5.South Africa, Russia, Siberia, Yakutia, Venezuela, GhanaGeochemistry, Garnets
DS1998-1140
1998
Pearson, N.J.Pearson, N.J., Griffin, W.L., Doyle, O'Reilly, KiviXenoliths from kimberlite pipes of the Lac de Gras area, Slave Craton, Canada.7th. Kimberlite Conference abstract, pp. 670-2.Northwest TerritoriesGeothermometry, Xenoliths
DS1998-1596
1998
Pearson, N.J.Wyatt, B.A., Morfi, L., Gurney, J.J., Pearson, N.J.Garnets in a polymict xenolith from the Bultfontein Mine: new preliminary geochemical and textural data.7th International Kimberlite Conference Abstract, pp. 968-70.South AfricaPeridotite, mineral chemistry, Deposit - Bultfontein
DS2000-0320
2000
Pearson, N.J.Gaul, O.F., Griffin, W.L., Pearson, N.J.Mapping olivine composition in the lithospheric mantleEarth and Planetary Science Letters, Vol. 182, No. 3-4, Nov. 15, pp. 223-35.MantleOlivine
DS2001-0897
2001
Pearson, N.J.Pearson, N.J., Griffin, Spetsius, O'ReillyIn situ Re Os analysis of mantle sulphides: a new microanalytical technique to unravel the evolution...Slave-Kaapvaal Workshop, Sept. Ottawa, 6p. abstractRussia, Siberia, YakutiaGeochronology, Deposit - Udachnaya
DS2002-0015
2002
Pearson, N.J.Alard, O., Griffin, W.L., Pearson, N.J., Lorand, J.P., O'Reilly, S.Y.New insights into the Re Os systematics of sub-continental lithospheric mantle from an insitu analysis of sulphides.Earth and Planetary Science Letters, Vol. 203, 3, pp. 651-663.MantleGeochronology
DS2002-0035
2002
Pearson, N.J.Andersen, T., Griffin, W.L., Pearson, N.J.Crustal evolution in the southwest part of the Baltic Shield: the Hf isotope evidenceJournal of Petrology, Vol. 43, 9, Sept.pp. 1725-48.Baltic Shield, NorwayTectonics, Geochronology
DS2002-0606
2002
Pearson, N.J.Graham, S., Lambert, D.D., Shee, S.R., Pearson, N.J.Juvenile lithospheric mantle enrichment and the formation of alkaline ultramafic magmaChemical Geology, Vol. 186, No. 2-4, pp. 215-33.Australia, westernMelnoites, Geochronology
DS2002-1236
2002
Pearson, N.J.Pearson, N.J., Alard, O., Griffin, Jackson, O'ReillyIn situ measurement of Re Os isotopes in mantle sulfides by laser ablation multicollector inductively..Geochimica et Cosmochimica Acta, Vol. 66, 6, pp. 1037-50.Russia, Siberia, Northwest TerritoriesCraton - mass spectrometry, rhenium, osmium, Peridotites
DS2002-1636
2002
Pearson, N.J.Van Achterbergh, E., Griffin, W.L., Ryan, C.G., O'Reilly, S.Y., Pearson, N.J.Subduction signature for quenched carbonatites from the deep lithosphereGeology, Vol.30,8,Aug.pp.743-6.MantleSubduction, Carbonatite
DS2003-0050
2003
Pearson, N.J.Aulbach, S., Griffin, W.L., Pearson, N.J., O'Reilly, S.Y., Kivi, K., Doyle, B.J.Origins of eclogites beneath the central Slave Craton8ikc, Www.venuewest.com/8ikc/program.htm, Session 2, POSTER abstractNorthwest TerritoriesEclogites and Diamonds
DS2003-0493
2003
Pearson, N.J.Graham, S., Lambert, D.D., Shee, S.R., Pearson, N.J.Erratum to juvenile lithospheric mantle enrichment and the formation of alkalineChemical Geology, Vol. Sept. 15, p.. 361. Original Vol. 186, pp. 215-233.AustraliaMelnoites, Geochronology
DS2003-0502
2003
Pearson, N.J.Griffin, W.L., O'Reilly, S.Y., Abe, N., Aulbach, S., Davies, R.M., Pearson, N.J.The origin and evolution of Archean lithospheric mantlePrecambrian Research, Vol. 127, 1-2, Nov. pp. 19-41.China, South Africa, Siberia, Northwest Territories, BoGeochemistry, SCLM, continental, Archon, metasomatism
DS2003-1051
2003
Pearson, N.J.Pearson, N.J., Griffin, W.L., O'Reilly, S.Y., Delpech, G.Magnesium isotopic compositions of olivine from the lithospheric mantle8 Ikc Www.venuewest.com/8ikc/program.htm, Session 4, AbstractRussia, Siberia, South Africa, Northwest TerritoriesMantle geochemistry
DS2003-1407
2003
Pearson, N.J.Van Achterbergh, E., Griffin, W.L., O'Reilly, S.Y., Ryan, C.G., Pearson, N.J.Melt inclusions from the deep Slave lithosphere: constraints on the origin and evolution8 Ikc Www.venuewest.com/8ikc/program.htm, Session 3, AbstractNorthwest TerritoriesDiamonds - melting
DS2003-1447
2003
Pearson, N.J.Wang, K.L., O'Reilly, S.Y., Griffin, W.L., Chung, S.L., Pearson, N.J.Proterozoic mantle lithosphere beneath the extended margin of the South Chin a block:Geology, Vol. 31, 8, pp. 709-712.ChinaGeochronology
DS200412-0034
2004
Pearson, N.J.Andersen, T., Griffin, W.L., Jackson, S.E., Knudsen, T.L., Pearson, N.J.Mid-Proterozoic magmatic arc evolution at the southwest margin of the Baltic Shield.Lithos, Vol. 73, 3-4, April pp. 289-318.Europe, Norway, Baltic ShieldMagmatism, Laser ablation, geochronology
DS200412-0076
2004
Pearson, N.J.Aulbach, S., Griffin, W.L., Pearson, N.J., O'Reilly, S.Y., Kivi, K., Doyle, B.J.Mantle formation and evolution, Slave Craton: constraints from HSE abundances and Re Os isotope systematics of sulfide inclusionChemical Geology, Vol. 208, 1-4, pp. 61-88.Canada, Northwest TerritoriesGeochronology, Lac de Gras, metasomatism, melt-deletion
DS200412-0708
2003
Pearson, N.J.Graham, S., Lambert, D.D., Shee, S.R., Pearson, N.J.Erratum to juvenile lithospheric mantle enrichment and the formation of alkaline ultramafic magma sources: Re Os Lu Hf and Sm NdChemical Geology, Vol. Sept. 15, p.. 361. Original Vol. 186, pp. 215-233.AustraliaMelnoites, geochronology
DS200412-0720
2004
Pearson, N.J.Griffin, W.L., Belousova, E.A., Shee, S.R., Pearson, N.J., O'Reilly, S.Y.Archean crustal evolution in the northern Yilgarn Craton: U Pb and Hf isotope evidence from detrital zircons.Precambrian Research, Vol. 131, 3-4, pp. 231-282.AustraliaGeochronology - Yilgarn
DS200412-0722
2004
Pearson, N.J.Griffin, W.L., Graham, S., O'Reilly, S.Y., Pearson, N.J.Lithosphere evolution beneath the Kaapvaal Craton: Re-Os systematics of sulfides in mantle derived peridotites.Chemical Geology, Vol. 208, 1-4, pp. 89-118.Africa, South Africa, LesothoGeochronology, Finsch, Kimberley, Jagersfontein
DS200412-0723
2003
Pearson, N.J.Griffin, W.L., O'Reilly, S.Y., Abe, N., Aulbach, S., Davies, R.M., Pearson, N.J., Doyle, B.J.,Kivi, K.The origin and evolution of Archean lithospheric mantle.Precambrian Research, Vol. 127, 1-2, Nov. pp. 19-41.China, Africa, Russia, Canada, Northwest TerritoriesGeochemistry, SCLM, continental, Archon, metasomatism
DS200412-0725
2004
Pearson, N.J.Griffin, W.L., O'Reilly, S.Y., Doyle, B.J., Pearson, N.J., Coopersmith, H., Kivi, K., Melkovets, V., PokhilenkLithosphere mapping beneath the North American plate.Lithos, Vol. 77, 1-4, Sept. pp. 873-922.Canada, Northwest Territories, Europe, GreenlandArchon, Proton, Tecton, Slave Craton, Kapuskasing Struc
DS200412-1511
2003
Pearson, N.J.Pearson, N.J., Griffin, W.L., O'Reilly, S.Y., Delpech, G.Magnesium isotopic compositions of olivine from the lithospheric mantle.8 IKC Program, Session 4, AbstractRussia, Siberia, Canada, Northwest territories, Africa, South AfricaMantle geochemistry
DS200412-2033
2003
Pearson, N.J.Van Achterbergh, E., Griffin, W.L., O'Reilly, S.Y., Ryan, C.G., Pearson, N.J., Kivi, K., Doyle, B.J.Melt inclusions from the deep Slave lithosphere: constraints on the origin and evolution of mantle derived carbonatite and kimbe8 IKC Program, Session 3, AbstractCanada, Northwest TerritoriesDiamonds - melting
DS200412-2080
2003
Pearson, N.J.Wang, K.L., O'Reilly, S.Y., Griffin, W.L., Chung, S.L., Pearson, N.J.Proterozoic mantle lithosphere beneath the extended margin of the South Chin a block: in situ Re Os evidence.Geology, Vol. 31, 8, pp. 709-712.ChinaGeochronology
DS200512-0008
2005
Pearson, N.J.Alard, O., Luguet, A., Pearson, N.J., Griffin, W.L., Lorand, J.P., Gannoun, A., Burton, K.W., O'Reilly, S.Y.In situ Os isotopes in abyssal peridotites bridge the isotopic gap between MORBS and their source mantle.Nature, Vol. 436, No. 7053, Aug. 18, pp. 1005-1108.MantleGeochronology
DS200512-0040
2005
Pearson, N.J.Aulbach, S., Griffin, W.L., Pearson, N.J., O'Reilly, S.Y., Kivi, K.Origin and evolution of the lithospheric mantle beneath the central Slave Craton, Canada.GAC Annual Meeting Halifax May 15-19, Abstract 1p.Canada, Northwest TerritoriesGeochronology, Lac de Gras, metasomatism
DS200512-0166
2005
Pearson, N.J.Choukroun, M., O'Reilly, S., Griffin, W.L., Pearson, N.J., Dawson, J.B.Hf isotopes of MARID (mica amphibole rutile ilmenite diopside) rutile trace metasomatic processes in the lithospheric mantle.Geology, Vol. 33, 1, Jan. pp. 45-48.Africa, South AfricaKimberley, metasomatism, xenoliths
DS200512-0234
2005
Pearson, N.J.Djomani, Y.H.P., O'Reilly, S.Y., Griffin, W.L., Natapov, L.M., Pearson, N.J., Doyle, B.J.Variations of the effective elastic thickness (Te) and structure of the lithosphere beneath the Slave Province, Canada.Exploration Geophysics, Vol. 36, 3, pp. 266-271.Canada, Northwest TerritoriesGeophysics - seismics, telurics
DS200512-1209
2005
Pearson, N.J.Xu, X., O'Reilly, S.Y., Griffin, W.L., Deng, P., Pearson, N.J.Relict Proterozoic basement in the Nanling Mountains (SE China) and its tectonothermal.Tectonics, Vol. 24, 2, TC2003001652ChinaGeothermometry
DS200612-0064
2005
Pearson, N.J.Babu, E.V.S.S.K., Griffin, W.L., O'Reilly, S.Y., Pearson, N.J.Sub-continental lithospheric mantle structure of the eastern Dharwar Craton, southern India at 1.1Ga: study of garnet xenocrysts from kimberlites.Geological Society of India, Bangalore November Meeting Group Discussion on Kimberlites and Related Rocks India, Abstract p. 73-74.India, Andhra Pradesh, Dharwar CratonTectonics
DS200612-0149
2006
Pearson, N.J.Bonadiman, C., Coltorti, M., Siena,F., O'Reilly, S.Y., Griffin, W.L., Pearson, N.J.Archean to Proterozoic depletion in Cape Verde lithospheric mantle.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 1, abstract only.Europe, Cape Verde IslandsGeochemistry
DS200612-0500
2006
Pearson, N.J.Griffin, W.L., Pearson, N.J., Belousova, E.A., Saeed, A.Hf isotope heterogeneity in zircon 91500.... comment.Chemical Geology, Vol. 233, 3-4, Oct. 15, pp. 358-363.TechnologyGeochronology
DS200612-0501
2006
Pearson, N.J.Griffin, W.L., Rege, S., O'Reilly, S.Y., Jackson, S.E., Pearson, N.J., Zedgenizov, D., Kurat, G.Trace element patterns of diamond: toward a unified genetic model.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 218. abstract only.TechnologyDiamond genesis geochemistry
DS200612-0705
2006
Pearson, N.J.Kinny, P.D., Love, G.J., Pearson, N.J.Hf isotopes and zircon recrystallization: a case study.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 18. abstract only.AustraliaGeochronology
DS200612-1061
2006
Pearson, N.J.Pearson, N.J., Griffin, W.L., Alard, O., O'Reilly, S.Y.The isotopic composition of magnesium in mantle olivine: records of depletion and metasomatism.Chemical Geology, Vol. 226, 3-4, pp. 115-133.Russia, Canada, Northwest Territories, AustraliaGeochronology
DS200612-1528
2006
Pearson, N.J.Wieland, P.R., Beyer, E., Jackson, S.E., Pearson, N.J., O'Reilly, S.Y.Evaluation of a method of the separation of Ni in geological samples.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 19 abstract only.TechnologyGeochemistry - nickel
DS200712-0037
2007
Pearson, N.J.Aulbach, S., Griffin, W.L., Pearson, N.J., O'Reilly, S.Y., Doyle, B.J.Lithosphere formation in the central Slave Craton ( Canada): plume subcretion or lithosphere accretion.Contributions to Mineralogy and Petrology, Vol. 154, 4, pp. 409-427.Canada, Northwest TerritoriesAccretion
DS200712-0038
2007
Pearson, N.J.Aulbach, S., Pearson, N.J., O'Reilly, S.Y., Doyle, B.J.Origins of xenolithic eclogites and pyroxenites from the Central Slave Craton, Canada.Journal of Petrology, Vol. 48, 10, pp. 1843-1873.Canada, Northwest TerritoriesEclogite, geochemistry, geochronology, isotopes
DS200812-0060
2008
Pearson, N.J.Aulbach, S., O'Reilly, S.Y., Griffin, W.L., Pearson, N.J.Subcontinental lithospheric mantle origin of high niobium/tantalum ratios in eclogites.Nature Geoscience, Vol. 1, 7, pp. 468-472.MantleEclogite
DS200812-0089
2008
Pearson, N.J.Batumike, J.M., Griffin, W.L., Belousa, E.A., Pearson, N.J., O'Reilly, S.Y., Shee, S.R.LAM-ICPMS U-Pb dating of kimberlite perovskite: Eocene-Oligocene kimberlites from the Kundelungu Plateau D.R. Congo.Earth and Planetary Science Letters, Vol. 267, 3-4, pp.609-619.Africa, Democratic Republic of CongoGeochrononoloy - Kundelungu
DS200812-0829
2008
Pearson, N.J.O'Reilly, S.Y., Griffin, W.L., Pearson, N.J., Jackson, S.E., Belousova, E.A., Alard, O., Saeed, A.Taking the pulse of the Earth: linking crustal and mantle events.Australian Journal of Earth Sciences, Vol. 55, pp. 983-995.MantleGeochronology
DS200812-0945
2008
Pearson, N.J.Rege, S., Griffin, W.L., Kurat, G., Jackson, S.E., Pearson, N.J., OReilly, S.Y.Trace element geochemistry of diamondite: crystallization of diamond from kimberlite carbonatite melts.Lithos, Vol. 106, 1-2, pp. 39-54.TechnologyDiamondite
DS200812-1283
2008
Pearson, N.J.Xu, X., Griffin, W.L., O'Reilly, S.Y., Pearson, N.J., Geng, H., Zheng, J.Re-Os isotopes of sulfides in mantle xenoliths from eastern China: progressive modifications of lithospheric mantle.Lithos, Vol. 102, 3-4, pp.43-64.ChinaGeochronology
DS200912-0018
2009
Pearson, N.J.Aulbach, S., Creaser, R.A., Pearson, N.J., Simonetti, S.S., Heaman, L.M., Griffin, W.L., Stachel, T.Sulfide and whole rock Re-Os systematics of eclogite and pyroxenite xenoliths from the Slave Craton, Canada.Earth and Planetary Science Letters, in press available,Canada, Northwest TerritoriesDeposit - Diavik
DS201012-0163
2010
Pearson, N.J.Donnelly, C.L., Griffin, W.L., O'Reilly, S.Y.,Pearson, N.J., Shee, S.R.The kimberlites and related rocks of the Kuruman kimberlite Province, Kaapvaal Craton, South Africa.Contributions to Mineralogy and Petrology, in press available 21p.Africa, South AfricaGeochemistry - trace elements
DS201012-0473
2010
Pearson, N.J.Marchesi, C., Griffin, W.L., Garrido, C.J., Bodinier, J-L., O'Reilly, S.Y., Pearson, N.J.Persistence of mantle lithospheric Re-Os signature during asthenospherization of the subcontinental lithospheric mantle: insights in situ sulphides....Contributions to Mineralogy and Petrology, Vol. 159, 3, pp. 315-330.Europe, SpainRonda peridotite
DS201112-0042
2011
Pearson, N.J.Aulbach, S., O'Reilly, S.Y., Pearson, N.J.Constraints from eclogite and MARID xenoliths on origins of mantle Zr/Hf-Nb/Ta variability.Contributions to Mineralogy and Petrology, Vol. 162, 5, pp. 1047-1062.Canada, Northwest Territories, Africa, South AfricaCarbonatite, kimberlites, Slave craton
DS201112-0043
2011
Pearson, N.J.Aulbach, S., O'Reilly, S.Y., Pearson, N.J.Constraints from eclogite and MARID xenoliths on origins of mantle Zr/Hf-Nb/Ta variability.Contributions to Mineralogy and Petrology, Vol. 162, 5, pp. 1047-1062.MantleEclogite
DS201112-0283
2011
Pearson, N.J.Donnelly, C.L., Griffin, W.L., O'Reilly, S.Y.,Pearson, N.J., Shee, S.R.The kimberlites and related rocks of the Kuruman kimberlite province, Kaapvaal craton, South Africa.Contributions to Mineralogy and Petrology, Vol. 161, 3, pp. 351-371.Africa, South AfricaDeposit -
DS201112-0387
2011
Pearson, N.J.Griffin, W.L., Begg, G., O'Reilly, S.Y., Pearson, N.J.Ore deposits and the SCLM.Goldschmidt Conference 2011, abstract p.946.MantleKimberlites - low degree melting prev. metasomatised
DS201112-1101
2011
Pearson, N.J.Wang, K-L., O'Reilly, S.Y., Griffin, W.L., Pearson, N.J., Kovach, V., Yarmolyuk, V.Primordial ages of lithospheric mantle vs ancient relicts in the asthenospheric mantle: in situ Os perspective.Goldschmidt Conference 2011, abstract p.2121.Russia, MongoliaConvection
DS201212-0167
2012
Pearson, N.J.Donnelly, C.L., Griffin, W.L., Yang, J-H., O'Reilly, Z.Y., li Li, Q., Pearson, N.J., Li, X-H.In situ U Pb dating and Sr Nd isotopic analysis of perovskite: constraints on the age and petrogenesis of the Kuruman kimberlite province, Kaapvaal Craton, South Africa.Journal of Petrology, Vol. 53, 12, pp. 2407-2522.Africa, South AfricaDeposit - Kuruman
DS201212-0310
2012
Pearson, N.J.Howell, D., O'Neill, C.J., Grant, K.J., Griffin, W.L., O'Reilly, S.Y., Pearson, N.J., Stern, R.A., Stachel, T.Platelet development in cuboid diamonds: insights from micro-FTIR mapping.Contributions to Mineralogy and Petrology, Vol. 164, 6, pp. 1011-1025.TechnologyDiamond morphology
DS201212-0314
2012
Pearson, N.J.Huang, J-X., Greau, Y., Griffin, W.L., O'Reilly, S.Y., Pearson, N.J.Multi-stage origin of Roberts Victor eclogites: progressive metasomatism and its isotopic effects.Lithos, in press availableAfrica, South AfricaDeposit - Roberts Victor
DS201212-0438
2012
Pearson, N.J.Malkovets, V.G., Griffin, W.L., Pearson, N.J., Rezvukhin, D.I., Oreilly, S.Y., Pokhilenko, N.P., Garanin, V.K., Spetsius, Z.V., Litasov, K.D.Late metasomatic addition of garnet to the SCLM: Os-itope evidence.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractMantleMetasomatism
DS201312-0039
2013
Pearson, N.J.Aulbach, S., Griffin, W.L., Pearson, N.J., O'Reilly, S.Y.Nature and timing of metasomatism in the stratified mantle lithosphere beneath the Central Slave Craton ( Canada).Chemical Geology, Vol. 352, pp. 153-169.Canada, Northwest TerritoriesCraton
DS201312-0320
2013
Pearson, N.J.Gonzalez-Jimienez, J.M., Marchesi, C., Griffin, W.L., Gutierrez-Narbona, R., Lorand, J-P., O'Reilly, S.Y., Garrido, C.J., Gervilla, F., Pearson, N.J., Hidas, K.Transfer of Os isotopic signatures from peridotite to chromitite in the subcontinental mantle: insights from in situ analysis of platinum-group and base metal minerals (Ojen peridotite massif, southern Spain.Lithos, Vol. 164-167, pp. 74-85.Europe, SpainChromitite
DS201312-0322
2013
Pearson, N.J.Gonzalez-Jimienez, J.M., Griffin, W.L., Gervilla, F., Proenza, J.A., O'Reilly, S.Y., Pearson, N.J.Chromitites in ophiolites: how, where, when, why? Part 1. A review of new ideas on the origin and significance of platinum-group minerals.Lithos, Vol. 189, pp. 127-139.MantleGeodynamics
DS201312-0336
2013
Pearson, N.J.Griffin, W.L., Belousova, E.A., O'Neill, C., O'Reilly, S.Y., Malkovets, V., Pearson, N.J., Spetsius, S., Wilde, S.A.The world turns over: Hadean-Archean crust mantle evolution.Lithos, Vol. 189, pp. 2-15.MantleCrust- mantle review
DS201312-0403
2013
Pearson, N.J.Howell, D., Griffin, W.L., Pearson, N.J., Powell, W., Wieland, P., O'Reilly, S.Y.Trace element partitioning in mixed habit diamonds.Chemical Geology, Vol. 355, pp. 134-143.TechnologyCrystallography
DS201312-0404
2013
Pearson, N.J.Howell, D., Stern, R.A., Griffin, W.L., Southworth, R., Mikhail, S., Stachel, T., Verchovsky, A.B., O'Reilly, S.Y., Pearson, N.J.New thermodynamic models and calculated phase equilibration temperatures in NCFMAS for basic and ultrabasic compositions through the transition zone into the uppermost lower mantle.Goldschmidt 2013, AbstractTechnologyCrystallography
DS201312-0407
2013
Pearson, N.J.Huang, J-X., Griffin, W.L., Greau, Y., Pearson, N.J., O'Reilly, S.Y.Unmasking enigmatic xenolithic eclogites: progressive metasomatism on a key Roberts Victor sample.Goldschmidt 2013, AbstractAfricaKamafugite
DS201412-0314
2014
Pearson, N.J.Griffin, W.L., Batumike, J.M., Greau, Y., Pearson, N.J., Shee, S.R., O'Reilly, S.Y.Emplacement ages and sources of kimberlites and related rocks in southern Africa: U-Pb ages and Sr-Nd isotopes of groundmass perovskite.Contributions to Mineralogy and Petrology, Vol. 167, pp. 1032-37.Africa, southern AfricaDeposit - geochronology
DS201412-0315
2014
Pearson, N.J.Griffin, W.L., Pearson, N.J., Andersen, T., Jackson, S.E., O'Reilly, S.Y., Zhang, M.Sources of cratonic metasomatic fluids: In-situ LA-MC-ICPMS analysis of Sr, Nd and Pb isotopes in Lima from the Jagersfontein kimberlite.American Journal of Science, Vol. 314, pp. 435-461.Africa, South AfricaDeposit - Jagersfontein
DS201412-0380
2014
Pearson, N.J.Huang, J-X., Griffin, W.L., Greau, Y., Pearson, N.J., O'Reilly, S.Y., Cliff, J., Martin, L.Unmasking xenolithic eclogites: progressive metasomatism of a key Roberts Victor sample.Chemical Geology, Vol. 364, pp. 55-65.Africa, South AfricaDeposit - Roberts Victor
DS201412-0381
2014
Pearson, N.J.Huang, J-X., Li, P., Griffin, W.L., Xia, Q-K, Greau, Y., Pearson, N.J., O'Reilly, S.Y.Water contents of Roberts Victor xenolithic eclogites: primary and metasomatic controls.Contributions to Mineralogy and Petrology, Vol. 168, pp. 1092-1095Africa, South AfricaDeposit - Roberts Victor
DS201502-0063
2014
Pearson, N.J.Huang, J-X., Li, P., Griffin, W.L., Xia, Q-K, Greau, Y., Pearson, N.J., O'Reilly, S.Y.Water contents of Roberts Victor xenolithic eclogites: primary and metasomatic controls.Contributions to Mineralogy and Petrology, Vol. 168, pp. 1092-1105.Africa, South AfricaDeposit - Roberts Victor
DS201504-0231
2015
Pearson, N.J.Xiong, Q., Griffin, W.L., Zheng, J-P., O'Reilly, S.Y., Pearson, N.J.Episodic refertilization and metasomatism of Archean mantle: evidence from an orogenic peridotite in North Qaidam ( NE Tibet) China.Contributions to Mineralogy and Petrology, Vol. 169, 24p.China, TibetPeridotite
DS201505-0246
2015
Pearson, N.J.Griffin, W.L., Gain, S.E.M., Toledo, V., O'Reilly, S.Y., Jacob, D., Pearson, N.J.Corundum, moissanite and super reducing conditions in the upper mantle beneath the lower ( southern) Galilee ( Israel).Israel Geological Society, 1p.posterEurope, IsraelMineralogy
DS201508-0379
2015
Pearson, N.J.Wang, K-L., Prikhodko, V., O'Reilly, S.Y., Griffin, W.L., Pearson, N.J., Kovach, V., Lizuka, Y., Chien, Y-H.Ancient mantle lithosphere beneath the Khanka Massif in Russian Far-East: in situ Re-Os evidence.Terra Nova, Vol. 27, 4, pp. 277-284.RussiaGeochronology
DS201512-1984
2015
Pearson, N.J.Wang, K-L., Prikhodo, V., O'Reilly, S.Y., Griffin, W.L., Pearson, N.J., Kovach, V., Iizuka, Y., Chien, Y-H.Ancient mantle lithosphere beneath the Khanka massif in the Russian Far East: in situ Re-Os evidence.Terra Nova, Vol. 27, 4, pp. 277-284.RussiaGeochronology

Abstract: The Os-isotope compositions of sulphides in mantle xenoliths hosted by Late Miocene alkali basalts from the Sviyaginsky volcano, Russian Far East, reveal the presence of Archaean-Proterozoic subcontinental lithospheric mantle beneath the Khanka massif. Their TMA and TRD model ages reveal similar peaks at 1.1 and 0.8 Ga suggesting later thermotectonic events in the subcontinental lithospheric mantle, whereas TRD model ages range back to 2.8 ± 0.5 (2?) Ga. The events recognized in the subcontinental lithospheric mantle are consistent with those recorded in the crust of the Khanka massif. The sulphide Os-isotope data show that the subcontinental lithospheric mantle beneath the Khanka massif had formed at least by the Mesoproterozoic, and was subsequently metasomatized by juvenile crustal-growth events related to the evolution of the Altaids. The Khanka massif is further proposed to have tectonic affinity to the Siberia Craton and should originate from it accordingly.
DS201603-0381
2016
Pearson, N.J.Griffin, W.L., Gain, S.E.M., Adams, D., Huang, J-X., Saunders, M.,Toledo, V., Pearson, N.J., O'Reilly, S.Y.Heaven on Earth: tistarite ( Ti203) and other nebular phases in corundum aggregates from Mt. Carmel volcanic rocks.Israel Geological Society, pp. 85-86. abstractEurope, IsraelMoissanite

Abstract: This ending talk, focused on the ongoing cooperative research of Prof. Griffin and his team at Macquarie University and Shefa Yamim, since January 2014, highlighting unique corundum species characteristics. Preliminary results of this research were presented in the IGS Annual Meeting of 2015, whereas this year Prof. Griffin has shared innovative findings only microscopically tracked within titanium-rich corundum aggregates. One of the more abundant minerals is Tistarite (Ti2O3), previously known only as a single grain in a primitive type of meteorite (!). An article has been submitted to a scientific journal detailing this first terrestrial occurrence. Several other minerals are common in meteorites, but unknown or extremely rare on Earth. About half of these minerals are unknown to science, and will be described as new minerals in the scientific literature. The first of these is a Titanium-Aluminium-Zirconium oxide, informally known as TAZ; it will be submitted to the International Mineralogical Association for recognition as a new mineral, ShefaTAZite. Using state of the art technologies such as Thermal Ionisation Mass Spectrometry (TIMS) and Electron Microscopy Facility (EMF) that has three scanning electron microscopes, all with EBSD capability, and a transmission electron microscope - Prof. Griffin revealed spectacular imagery of minerals and rare compounds associated with titanium rich corundum aggregates.
DS201603-0382
2016
Pearson, N.J.Griffin, W.L., Gain, S.E.M., Adams, D., Toledo, V., Pearson, N.J., O'Reilly, S.Y.Deep-Earth methane, mantle dynamics and mineral exploration: insights from northern Israel, southern Tibet and Kamchatka.Israel Geological Society, pp. 87-88. abstractEurope, Israel, TibetMoissanite
DS201603-0407
2016
Pearson, N.J.O'Reilly, S.Y., Griffin, W.L., Pearson, N.J.The role of the deep lithosphere in metallogeny.Israel Geological Society, pp. 144-145. abstractMantleSCLM - geodynamics

Abstract: This talk shortly reviewed geological and geochemical mechanisms of the deep lithosphere, a layer composed of the Earth's crust and uppermost mantle at a depth range of 100-150km below the surface. Definition of these processes at depth, reflects on surface recovery of gem and heavy minerals, of which metallic minerals were stressed out. Prof. O'reilley has also referred to Shefa Yamim's exploration area in northern Israel where the eruption of gem-bearing volcanic rocks appears to be related to a major lithospheric suture (the Dead Sea Transform) and related faulting. The Dead Sea Transform is a 1000km plate boundary stretching out from Turkey in the north to Eilat Bay in the south. As such, it is a preferred pathway for magma emplacement crystalizing in volcanic bodies that are being surveyed by Shefa Yamim as Primary Sources for gem and heavy minerals.
DS201604-0597
2016
Pearson, N.J.Castilo-Oliver, M., Gali, S., Melgarejo, J.C., Griffin, W.L., Belousova, E., Pearson, N.J., Watangua, M., O'Reilly, S.Y.Trace element geochemistry and U-Pb dating of perovskite in kimberlites of the Lunda Norte province ( NE Angola): petrogenetic and tectonic implications.Chemical Geology, Vol. 426, pp. 118-134.Africa, AngolaGeochronology

Abstract: Perovskite (CaTiO3) has become a very useful mineral for dating kimberlite eruptions, as well as for constraining the compositional evolution of a kimberlitic magma and its source. Despite the undeniable potential of such an approach, no similar study had been done in Angola, the fourth largest diamond producer in Africa. Here we present the first work of in situ U-Pb geochronology and Sr-Nd isotope analyses of perovskite in six Angolan kimberlites, supported by a detailed petrographic and geochemical study of their perovskite populations. Four types of perovskite were identified, differing in texture, major- and trace-element composition, zoning patterns, type of alteration and the presence or absence of inclusions. Primary groundmass perovskite is classified either as anhedral, Na-, Nb- and LREE-poor perovskite (Ia); or euhedral, strongly zoned, Na-, Nb- and LREE-rich perovskite (Ib). Secondary perovskite occurs as reaction rims on ilmenite (IIa) or as high Nb (up to 10.6 wt% Nb2O5) perovskite rims on primary perovskite (IIb). The occurrence of these four types within the Mulepe kimberlites is interpreted as an evidence of a complex, multi-stage process that involved mingling of compositionally different melts. U-Pb dating of these perovskites yielded Lower Cretaceous ages for four of the studied kimberlites: Mulepe 1 (116.2 ± 6.5 Ma), Mulepe 2 (123.0 ± 3.6 Ma), Calonda (119.5 ± 4.3 Ma) and Cat115 (133 ± 10 Ma). Kimberlite magmatism occurred in NE Angola likely due to reactivation of deep-seated translithospheric faults (> 300 km) during the break-up of Gondwana. Sr-Nd isotope analyses of four of these kimberlites indicate that they are Group I kimberlites, which is consistent with the petrological observations.
DS201605-0819
2016
Pearson, N.J.Castillo-Oliver, M., Gali, S., Melgarejo, J.C., Griffin, W.L., Belousova, E., Pearson, N.J., Watangua, M., O'Reilly, S.Y.Trace element geochemistry and U-Pb dating of perovskite in kimberlites of the Lunda Norte province ( NE Angola): petrogenetic and tectonic implications.Chemical Geology, Vol. 426, pp. 118-134.Africa, AngolaDeposit - Alto Cuilo

Abstract: Perovskite (CaTiO3) has become a very usefulmineral for dating kimberlite eruptions, aswell as for constraining the compositional evolution of a kimberlitic magma and its source. Despite the undeniable potential of such an approach, no similar study had been done in Angola, the fourth largest diamond producer in Africa. Here we present the firstwork of in situ U-Pb geochronology and Sr-Ndisotope analyses of perovskite in six Angolan kimberlites, supported by a detailed petrographic and geochemical study of their perovskite populations. Four types of perovskitewere identified, differing in texture,major- and trace-element composition, zoning patterns, type of alteration and the presence or absence of inclusions. Primary groundmass perovskite is classified either as anhedral, Na-, Nb- and LREE-poor perovskite (Ia); or euhedral, strongly zoned, Na-, Nb- and LREE-rich perovskite (Ib). Secondary perovskite occurs as reaction rims on ilmenite (IIa) or as high Nb (up to 10.6 wt% Nb2O5) perovskite rims on primary perovskite (IIb). The occurrence of these four types within the Mulepe kimberlites is interpreted as an evidence of a complex, multi-stage process that involved mingling of compositionally different melts. U-Pb dating of these perovskites yielded Lower Cretaceous ages for four of the studied kimberlites: Mulepe 1 (116.2±6.5Ma),Mulepe 2 (123.0±3.6Ma), Calonda (119.5±4.3 Ma) and Cat115 (133±10Ma). Kimberlite magmatism occurred in NE Angola likely due to reactivation of deep-seated translithospheric faults (N300 km) during the break-up of Gondwana. Sr-Nd isotope analyses of four of these kimberlites indicate that they are Group I kimberlites, which is consistent with the petrological observations.
DS201606-1090
2016
Pearson, N.J.Griffin, W.L., Afonso, J.C., Belousova, E.A., Gain, S.E., Gong, X-H., Gonzalez-Jiminez, J.M., Howell, D., Huang, J-X., McGowan, N., Pearson, N.J., Satsukawa, T., Shi R., Williams, P., Xiong, Q., Yang, J-S., Zhang, M., O'Reilly, S.Y.Mantle recycling: transition zone metamorphism of Tibetan ophiolitic peridotites and its tectonic implications.Journal of Petrology, in press available, 30p.Asia, China, TibetPeridotite

Abstract: Large peridotite massifs are scattered along the 1500?km length of the Yarlung-Zangbo Suture Zone (southern Tibet, China), the major suture between Asia and Greater India. Diamonds occur in the peridotites and chromitites of several massifs, together with an extensive suite of trace phases that indicate extremely low fO2 (SiC, nitrides, carbides, native elements) and/or ultrahigh pressures (UHP) (diamond, TiO2 II, coesite, possible stishovite). New physical and isotopic (C, N) studies of the diamonds indicate that they are natural, crystallized in a disequilibrium, high-T environment, and spent only a short time at mantle temperatures before exhumation and cooling. These constraints are difficult to reconcile with previous models for the history of the diamond-bearing rocks. Possible evidence for metamorphism in or near the upper part of the Transition Zone includes the following: (1) chromite (in disseminated, nodular and massive chromitites) containing exsolved pyroxenes and coesite, suggesting inversion from a high-P polymorph of chromite; (2) microstructural studies suggesting that the chromitites recrystallized from fine-grained, highly deformed mixtures of wadsleyite and an octahedral polymorph of chromite; (3) a new cubic Mg-silicate, with the space group of ringwoodite but an inverse-spinel structure (all Si in octahedral coordination); (4) harzburgites with coarsely vermicular symplectites of opx + Cr-Al spinel ± cpx; reconstructions suggest that these are the breakdown products of majoritic garnets, with estimated minimum pressures to?>?13?GPa. Evidence for a shallow pre-metamorphic origin for the chromitites and peridotites includes the following: (1) trace-element data showing that the chromitites are typical of suprasubduction-zone (SSZ) chromitites formed by magma mixing or mingling, consistent with Hf-isotope data from magmatic (375?Ma) zircons in the chromitites; (2) the composition of the new cubic Mg-silicate, which suggests a low-P origin as antigorite, subsequently dehydrated; (3) the peridotites themselves, which carry the trace element signature of metasomatism in an SSZ environment, a signature that must have been imposed before the incorporation of the UHP and low-fO2 phases. A proposed P-T-t path involves the original formation of chromitites in mantle-wedge harzburgites, subduction of these harzburgites at c. 375?Ma, residence in the upper Transition Zone for >200 Myr, and rapid exhumation at c. 170-150?Ma or 130-120?Ma. Os-isotope data suggest that the subducted mantle consisted of previously depleted subcontinental lithosphere, dragged down by a subducting oceanic slab. Thermomechanical modeling shows that roll-back of a (much later) subducting slab would produce a high-velocity channelized upwelling that could exhume the buoyant harzburgites (and their chromitites) from the Transition Zone in?
DS201606-1093
2015
Pearson, N.J.Howell, D., Griffin, W.L., Yang, J., Gain, S., Stern, R.A., Huang, J-X., Jacob, D.E., Xu, X., Stokes, A.J., O'Reilly, S.Y., Pearson, N.J.Diamonds in ophiolites: contamination or a new diamond growth environment?Earth and Planetary Science Letters, Vol. 430, pp. 284-295.Asia, TibetLuobusa Massif Type Iib

Abstract: For more than 20 years, the reported occurrence of diamonds in the chromites and peridotites of the Luobusa massif in Tibet (a complex described as an ophiolite) has been widely ignored by the diamond research community. This skepticism has persisted because the diamonds are similar in many respects to high-pressure high-temperature (HPHT) synthetic/industrial diamonds (grown from metal solvents), and the finding previously has not been independently replicated. We present a detailed examination of the Luobusa diamonds (recovered from both peridotites and chromitites), including morphology, size, color, impurity characteristics (by infrared spectroscopy), internal growth structures, trace-element patterns, and C and N isotopes. A detailed comparison with synthetic industrial diamonds shows many similarities. Cubo-octahedral morphology, yellow color due to unaggregated nitrogen (C centres only, Type Ib), metal-alloy inclusions and highly negative View the MathML source?C13 values are present in both sets of diamonds. The Tibetan diamonds (n=3n=3) show an exceptionally large range in View the MathML source?N15 (?5.6 to +28.7‰+28.7‰) within individual crystals, and inconsistent fractionation between {111} and {100} growth sectors. This in contrast to large synthetic HPHT diamonds grown by the temperature gradient method, which have with View the MathML source?N15=0‰ in {111} sectors and +30‰+30‰ in {100} sectors, as reported in the literature. This comparison is limited by the small sample set combined with the fact the diamonds probably grew by different processes. However, the Tibetan diamonds do have generally higher concentrations and different ratios of trace elements; most inclusions are a NiMnCo alloy, but there are also some small REE-rich phases never seen in HPHT synthetics. These characteristics indicate that the Tibetan diamonds grew in contact with a C-saturated Ni-Mn-Co-rich melt in a highly reduced environment. The stable isotopes indicate a major subduction-related contribution to the chemical environment. The unaggregated nitrogen, combined with the lack of evidence for resorption or plastic deformation, suggests a short (geologically speaking) residence in the mantle. Previously published models to explain the occurrence of the diamonds, and other phases indicative of highly reduced conditions and very high pressures, have failed to take into account the characteristics of the diamonds and the implications for their formation. For these diamonds to be seriously considered as the result of a natural growth environment requires a new understanding of mantle conditions that could produce them.
DS201610-1865
2016
Pearson, N.J.Griffin, W.L., Gain, S.E.M., Adams, D.T., Huang, J-X., Saunders, M., Toledo, V., Pearson, N.J., O'Reilly, S.Y.First terrestrial occurrence of tistarite ( Ti2O3): ultra-low oxygen fugacity in the upper mantle beneath Mount Carmel, Israel.Geology, Vol. 44, 10, pp. 815-818.Europe, IsraelMoissanite

Abstract: The minimum oxygen fugacity (fO2) of Earth's upper mantle probably is controlled by metal saturation, as defined by the iron-wüstite (IW) buffer reaction (FeO ? Fe + O). However, the widespread occurrence of moissanite (SiC) in kimberlites, and a suite of super-reduced minerals (SiC, alloys, native elements) in peridotites in Tibet and the Polar Urals (Russia), suggest that more reducing conditions (fO2 = 6-8 log units below IW) must occur locally in the mantle. We describe pockets of melt trapped in aggregates of corundum crystals ejected from Cretaceous volcanoes in northern Israel which contain high-temperature mineral assemblages requiring extremely low fO2 (IW < -10). One abundant phase is tistarite (Ti2O3), previously known as a single grain in the Allende carbonaceous chondrite (Mexico) and believed to have formed during the early evolution of the solar nebula. It is associated with other reduced phases usually found in meteorites. The development of super-reducing conditions in Earth's upper mantle may reflect the introduction of CH4 + H2 fluids from the deep mantle, specifically related to deep-seated volcanic plumbing systems at plate boundaries.
DS201610-1872
2016
Pearson, N.J.Huang, J-X., Xiang, Y., An, Y., Griffin, W.L., Greau, Y., Xie, L., Pearson, N.J., Yu, H., O'Reilly, S.Y.Magnesium and oxygen isotopes in Roberts Victor eclogites.Chemical Geology, Vol. 438, pp. 73-83.Africa, South AfricaDeposit - Roberts Victor

Abstract: Magnesium and oxygen are critical elements in the solid Earth and hydrosphere. A better understanding of the combined behavior of Mg and O isotopes will refine their use as a tracer of geochemical processes and Earth evolution. In this study, the Mg-isotope compositions of garnet and omphacite separated from well-characterized xenolithic eclogites from the Roberts Victor kimberlite pipe (South Africa) have been measured by solution multi-collector ICP-MS. The reconstructed whole-rock ?26Mg values of Type I (metasomatized) eclogites range from ? 0.61‰ to ? 0.20‰ (Type IA) and from ? 0.60‰ to ? 0.30‰ (Type IB) (mean ? 0.43‰ ± 0.12‰), while ?26Mg of Type IIA (fresh, least metasomatized) eclogites ranges from ? 1.09‰ to ? 0.17‰ (mean ? 0.69‰ ± 0.41‰); a Type IIB (fresh, least metasomatized) has ?26Mg of ? 0.37‰. Oxygen-isotope compositions of garnet were analyzed in situ by SIMS (CAMECA 1280) and cross-checked by laser fluorination. Garnets have ?18O of 6.53‰ to 9.08‰ in Type IA, 6.14‰ to 6.65‰ in Type IB, and 2.34‰ to 2.91‰ in Type IIB. The variation of ?26Mg and ?18O in Type IA and IB eclogites is consistent with the previously proposed model for the evolution of these samples, based on major and trace elements and radiogenic isotopes. In this model, the protoliths (Type II eclogites) were metasomatized by carbonatitic to kimberlitic melts/fluids to produce first Type IA eclogites and then Type IB. Metasomatism has changed the O-isotope compositions, but the Mg-isotope compositions of Type IA are mainly controlled by the protoliths; those of Type IB eclogites reflect mixing between the protoliths and the kimberlitic melt/fluid. The combination of a large range of ?26Mg and low ?18O in Type II eclogites cannot be explained easily by seawater alteration of oceanic crust, interaction of carbonate/silicate sediments with oceanic crust, or partial melting of mafic rocks.
DS201701-0035
2016
Pearson, N.J.Tretiakova, I.G., Belousova, E.A., Malkovets, V.G., Griffin, W.L., Piazolo, S., Pearson, N.J., O'Reilly, S.Y., Nishido, H.Recurrent magmatic activity on a lithosphere scale structure: crystallization and deformation in kimberlitic zircons.Gondwana Research, Vol. 42, pp. 126-132.RussiaDeposit - Nubinskaya

Abstract: Kimberlites are not only the most economically important source of diamonds; they also carry unique information encapsulated in rock fragments entrained as the magma traverses the whole thickness of the lithosphere. The Nurbinskaya pipe in the Siberian kimberlite province (Russia) is one of several intruded along the Vilyui Rift, a major terrane boundary. The pipe contains three populations of mantle-derived zircon xenocrysts: Archean (mean age 2709 ± 9 Ma), Devonian (mean age 371 ± 2.3 Ma), and a subset of grains with evidence of brittle deformation and rehealing, and a range of ages between 370 and 450 Ma. The Hf-isotope, O-isotope and trace-element signatures of the last group provide a link between the Archean and Devonian events, indicating at least three episodes of magmatic activity and zircon crystallization in the lithosphere beneath the pipe. The emplacement of the Nurbinskaya pipe ca 370 Ma ago was only the youngest activity in a magma plumbing system that has been periodically reactivated over at least 2.7 billion years, controlled by the lithosphere-scale structure of the Vilyui Rift.
DS201702-0254
2017
Pearson, N.J.Xu, B., Griffin, W.L., Xiong, Q., Hou, Z-Q, O'Reilly, S.Y., Guo, Z., Pearson, N.J., Greau, Y., Yang, Z-M., Zheng, Y-C.Ultrapotassic rocks and xenoliths from South Tibet: contrasting styles of interaction between lithospheric mantle and asthenosphere during continental collision.Geology, Vol. 45, 1, pp. 51-54.China, TibetUPR - metasomatism

Abstract: Widespread Miocene (24-8 Ma) ultrapotassic rocks and their entrained xenoliths provide information on the composition, structure, and thermal state of the sub-continental lithospheric mantle in southern Tibet during the India-Asia continental collision. The ultrapotassic rocks along the Lhasa block delineate two distinct lithospheric domains with different histories of depletion and enrichment. The eastern ultrapotassic rocks (89°E-92°E) reveal a depleted, young, and fertile lithospheric mantle (87Sr/86Srt = 0.704-0.707 [t is eruption time]; Hf depleted-mantle model age [TDM] = 377-653 Ma). The western ultrapotassic rocks (79°E-89°E) and their peridotite xenoliths (81°E) reflect a refractory harzburgitic mantle refertilized by ancient metasomatism (lavas: 87Sr/86Srt = 0.714-0.734; peridotites: 87Sr/86Srt = 0.709-0.716). These data integrated with seismic tomography suggest that upwelling asthenosphere was diverted away from the deep continental root beneath the western Lhasa block, but rose to shallower depths beneath a thinner lithosphere in the eastern part. Heating of the lithospheric mantle by the rising asthenosphere ultimately generated the ultrapotassic rocks with regionally distinct geochemical signatures reflecting the different nature of the lithospheric mantle.
DS201706-1094
2017
Pearson, N.J.Lu, J-G, Xiong, Q., Griffin, W.L., Zheng, J-P., Huang, J-X., O'Reilly, S.Y., Satsuskawa, T., Pearson, N.J.Uplift of the southeastern Australian lithosphere: thermal tectonic evolution of garnet pyroxenite xenoliths from western Victoria.Geological Society of America, SPE 526 pp. 27-48.Australiageothermometry

Abstract: Detailed petrography, microstructure, and geochemistry of garnet pyroxenite xenoliths in Holocene basanite tuffs from maars at Lakes Bullenmerri and Gnotuk (western Victoria, southeastern Australia) have been used to track their igneous and metamorphic history, enabling the reconstruction of the thermal-tectonic evolution of the lithospheric mantle. The exsolution of orthopyroxene and garnet and rare spinel, plagioclase, and ilmenite from complex clinopyroxene megacrysts suggests that the xenoliths originally were clinopyroxene-dominant cumulates associated with minor garnet, orthopyroxene, or spinel. The compositions of exsolved phases and their host clinopyroxene were reintegrated using measured modal proportions to show that the primary clinopyroxene was enriched in Al2O3 (5.53-13.63 wt%) and crystallized at ~1300-1500 °C and 16-30 kbar. These cumulates then underwent extensive exsolution, recrystallization, and reaction during cooling, and finally equilibrated at ~950-1100 °C and 12-18 kbar before entrainment in the basanites. Rare earth element (REE) thermobarometry of garnets and coexisting clinopyroxenes preserves evidence of an intermediate stage (1032 °C and 21 kbar). These results imply that the protoliths of the garnet pyroxenite formed at a range of depths from ~50 to 100 km, and then during or shortly after cooling, they were tectonically emplaced to higher levels (~40-60 km; i.e., uplifted by at least 10-20 km) along the prevailing geotherm. This uplift may have been connected with lithosphere-scale faulting during the Paleozoic orogeny, or during Mesozoic-Cenozoic rifting of eastern Australia.
DS201708-1576
2017
Pearson, N.J.Lu, J-G., Xiong, Q., Griffin, W.L., Zheng, J-P., Huang, J-X., O'Reilly, S.Y., Satsukawa, T., Pearson, N.J.Uplift of southeastern Australian lithosphere: thermal tectonic evolution of garnet pyroxenite xenoliths from western Victoria.Geological Society of London, Chapter 2, pp. 27-48.Australia, Victoriaxenoliths

Abstract: Detailed petrography, microstructure, and geochemistry of garnet pyroxenite xenoliths in Holocene basanite tuffs from maars at Lakes Bullenmerri and Gnotuk (western Victoria, southeastern Australia) have been used to track their igneous and metamorphic history, enabling the reconstruction of the thermal-tectonic evolution of the lithospheric mantle. The exsolution of orthopyroxene and garnet and rare spinel, plagioclase, and ilmenite from complex clinopyroxene megacrysts suggests that the xenoliths originally were clinopyroxene-dominant cumulates associated with minor garnet, orthopyroxene, or spinel. The compositions of exsolved phases and their host clinopyroxene were reintegrated using measured modal proportions to show that the primary clinopyroxene was enriched in Al2O3 (5.53–13.63 wt%) and crystallized at ~1300–1500 °C and 16–30 kbar. These cumulates then underwent extensive exsolution, recrystallization, and reaction during cooling, and finally equilibrated at ~950–1100 °C and 12–18 kba
DS201710-2280
2017
Pearson, N.J.Xiong, Q., Griffin, W.L., Huang, J-X., Gain, S.E.M., Toledo, V., Pearson, N.J., O'Reilly, S.Y.Super reduced assemblages in "ophiolitic" chromitites and peridotites: the view from Mount Carmel.European Journal of Mineralogy, Vol. 29, 4, pp. 557-570.Europe, Israelmineralogy

Abstract: Ultrahigh-pressure (UHP) materials (e.g., diamond, high-pressure polymorph of chromite) and super-reduced (SuR) phases (e.g., carbides, nitrides, silicides and native metals) have been identified in chromitites and peridotites of the Tibetan and Polar-Urals ophiolites. These unusual assemblages suggest previously unrecognized fluid- or melt-related processes in the Earth’s mantle. However, the origin of the SuR phases, and in particular their relationships with the UHP materials in the ophiolites, are still enigmatic. Studies of a recently recognized SuR mineral system from Cretaceous volcanics on Mt Carmel, Israel, suggest an alternative genesis for the ophiolitic SuR phases. The Mt Carmel SuR mineral system (associated with Ti-rich corundum xenocrysts) appears to reflect the local interaction of mantle-derived CH4 ± H2 fluids with basaltic magmas in the shallow lithosphere (depths of ?30-100 km). These interactions produced desilication of the magma, supersaturation in Al2O3 leading to rapid growth of corundum, and phase assemblages requiring local oxygen fugacity (fO2) gradually dropping to ?11 log units below the iron-wüstite (IW) buffer. The strong similarities between this system and the SuR phases and associated Ti-rich corundum in the Tibetan and Polar-Urals ophiolites suggest that the ophiolitic SuR suite probably formed by local influx of CH4 ± H2 fluids within previously subducted peridotites (and included chromitites) during their rapid exhumation from the deep upper mantle to lithospheric levels. In the final stages of their ascent, the recycled peridotites and chromitites were overprinted by a shallow magmatic system similar to that observed at Mt Carmel, producing most of the SuR phases and eventually preserving them within the Tibetan and Polar-Urals ophiolites.
DS201711-2506
2017
Pearson, N.J.Castillo-Oliver, M., Melgarejo, J.C., Gali, S., Pervov, V., Goncalves, A.O., Griffin, W.L., Pearson, N.J., O'Reilly, S.Y.Use and misuse of Mg- and Mn- rich ilmenite in diamond exploration: a petrographic and trace element approach. Congo-Kasai cratonLithos, Vol. 292-293, pp. 348-363.Africa, Angoladeposit - CAT115, Tchiuzo

Abstract: Magnesian ilmenite is a common kimberlite indicator mineral, although its use in diamond exploration is still controversial. Complex crystallisation and replacement processes have been invoked to explain the wide compositional and textural ranges of ilmenite found in kimberlites. This work aims to shed light on these processes, as well as their implications for diamond exploration. Petrographic studies were combined for the first time with both major- and trace-element analyses to characterise the ilmenite populations found in xenoliths and xenocrysts in two Angolan kimberlites (Congo-Kasai craton). A multi-stage model describes the evolution of ilmenite in these pipes involving: i) crystallisation of ferric and Mg-rich ilmenite either as metasomatic phases or as megacrysts, both in crustal and in metasomatised mantle domains; ii) kimberlite entrainment and xenolith disaggregation producing at least two populations of ilmenite nodules differing in composition; iii) interaction of both types with the kimberlitic magma during eruption, leading to widespread replacement by Mg-rich ilmenite along grain boundaries and fractures. This process produced similar major-element compositions in ilmenites regardless of their primary (i.e., pre-kimberlitic) origin, although the original enrichment in HFSE (Zr, Hf, Ta, Nb) observed in Fe3 +-rich xenocrysts is preserved. Finally (iv) formation of secondary Mn-ilmenite by interaction with a fluid of carbonatitic affinity or by infiltration of a late hydrothermal fluid, followed in some cases by subsolidus alteration in an oxidising environment. The complexities of ilmenite genesis may lead to misinterpretation of the diamond potential of a kimberlite during the exploration stage if textural and trace-element information is disregarded. Secondary Mg-enrichment of ilmenite xenocrysts is common and is unrelated to reducing conditions that could favour diamond formation/preservation in the mantle. Similarly, Mn-rich ilmenite should be disregarded as a diamond indicator mineral, unless textural studies can prove its primary origin.
DS201902-0287
2019
Pearson, N.J.Kourim, F., Beinlich, A., Wang, K.L., Michibayashi, K., O'Reilly, S.Y., Pearson, N.J.Feedback of mantle metasomatism on olivine micro-fabric and seismic properties of the deep lithosphere. Lithos, Vol. 328, pp. 43-57.Asia, Taiwanmetasomatism

Abstract: The interaction of hydrous fluids and melts with dry rocks of the lithospheric mantle inevitably modifies their viscoelastic and chemical properties due to the formation of compositionally distinct secondary phases. In addition, melt percolation and the associated metasomatic alteration of mantle rocks may also facilitate modification of the pre-existing rock texture and olivine crystallographic preferred orientation (CPO) and thus seismic properties. Here we explore the relationship between mantle metasomatism, deformation and seismic anisotropy using subduction-related mantle xenoliths from the Penghu Islands, western Taiwan. The investigated xenoliths have equilibrated at upper lithospheric mantle conditions (879?°C to 1127?°C) based on pyroxene geothermometry and show distinct variations in clinopyroxene chemical composition, texture and olivine CPO allowing for the classification of two distinct groups. Group 1 xenoliths contain rare earth element (REE) depleted clinopyroxene, show a porphyroclastic texture and olivine grains are mostly characterized by [100]-axial pattern symmetries. In contrast, REE-enriched clinopyroxene from Group 2 xenoliths occur in a fine-grained equigranular texture and coexisting olivine frequently displays [010]-axial pattern symmetries. The clinopyroxene compositions are indicative of cryptic and modal to stealth metasomatic alteration of Group 1 and Group 2 xenoliths, respectively. Furthermore, the observed olivine [100]-axial pattern of Group 1 xenoliths reflects deformation by dislocation creep at high temperature, low pressure and dry conditions, whereas olivine [010]-axial patterns of Group 2 xenoliths imply activation of olivine [001] glide planes along preferentially wet (010) grain boundaries. This correlation indicates that the variation in olivine CPO symmetry from [100]- to [010]-axial pattern in Penghu xenoliths results from deformation and intra-crystalline recovery by subgrain rotation during metasomatic alteration induced by melt percolation. The microstructural observations and olivine CPO combined with petrological and geochemical data suggest that Group 1 xenoliths preserve microstructural and chemical characteristics of an old, probably Proterozoic lithosphere, while Group 2 xenoliths record localized Miocene deformation associated with wall-rock heating and metasomatism related to melt circulation. Furthermore, the observed transition of olivine CPO from [100]-axial pattern to [010]-axial pattern by deformation in the presence of variable melt fractions and associated metasomatic alteration can be inferred to modify the physical properties of mantle rocks.
DS201905-1052
2019
Pearson, N.J.Kourim, F., Beinlich, A., Wang, K-L., Michibayashi, K., O'Reilly, S.Y., Pearson, N.J.Feedback of mantle metasomatism on olivine micro-fabric and seismic properties of the deep lithosphere.Lithos, Vol. 328-329, pp. 43-57.Asia, Taiwan, Penghu Islandsmetasomatism

Abstract: The interaction of hydrous fluids and melts with dry rocks of the lithospheric mantle inevitably modifies their viscoelastic and chemical properties due to the formation of compositionally distinct secondary phases. In addition, melt percolation and the associated metasomatic alteration of mantle rocks may also facilitate modification of the pre-existing rock texture and olivine crystallographic preferred orientation (CPO) and thus seismic properties. Here we explore the relationship between mantle metasomatism, deformation and seismic anisotropy using subduction-related mantle xenoliths from the Penghu Islands, western Taiwan. The investigated xenoliths have equilibrated at upper lithospheric mantle conditions (879?°C to 1127?°C) based on pyroxene geothermometry and show distinct variations in clinopyroxene chemical composition, texture and olivine CPO allowing for the classification of two distinct groups. Group 1 xenoliths contain rare earth element (REE) depleted clinopyroxene, show a porphyroclastic texture and olivine grains are mostly characterized by [100]-axial pattern symmetries. In contrast, REE-enriched clinopyroxene from Group 2 xenoliths occur in a fine-grained equigranular texture and coexisting olivine frequently displays [010]-axial pattern symmetries. The clinopyroxene compositions are indicative of cryptic and modal to stealth metasomatic alteration of Group 1 and Group 2 xenoliths, respectively. Furthermore, the observed olivine [100]-axial pattern of Group 1 xenoliths reflects deformation by dislocation creep at high temperature, low pressure and dry conditions, whereas olivine [010]-axial patterns of Group 2 xenoliths imply activation of olivine [001] glide planes along preferentially wet (010) grain boundaries. This correlation indicates that the variation in olivine CPO symmetry from [100]- to [010]-axial pattern in Penghu xenoliths results from deformation and intra-crystalline recovery by subgrain rotation during metasomatic alteration induced by melt percolation. The microstructural observations and olivine CPO combined with petrological and geochemical data suggest that Group 1 xenoliths preserve microstructural and chemical characteristics of an old, probably Proterozoic lithosphere, while Group 2 xenoliths record localized Miocene deformation associated with wall-rock heating and metasomatism related to melt circulation. Furthermore, the observed transition of olivine CPO from [100]-axial pattern to [010]-axial pattern by deformation in the presence of variable melt fractions and associated metasomatic alteration can be inferred to modify the physical properties of mantle rocks.
DS201911-2544
2019
Pearson, N.J.Malkovets, V.G., Rezvukhin, D.I., Griffin, W.L., Tretiakova, I.G., Pearson, N.J., Gibsher, A.A., Belousova, E.A., Zedgenizov, D.A., O'Reilly, S.Y.Re-Os dating of sulfide inclusions in Cr-pyropes from the Upper Muna kimberlites.Goldschmidt2019, 1p. AbstractRussiadeposit - Upper Muna

Abstract: Archean cratons are underlain by highly depleted subcontinental lithospheric mantle (SCLM). However, there are extensive evidences that Archean SCLM has been extensively refertilized by metasomatic processes, with the addition of Fe, Ca, and Al to depleted protoliths. The distribution of sub-calcic Cr-rich garnets in the SCLM beneath the Siberian craton suggests (1) sub-calcic garnets and diamonds are metasomatic phases in the cratonic SCLM; (2) the distribution of both phases is laterally heterogeneous on relatively small scales and related to ancient structural controls [1]. Re-Os isotopic compositions of twenty six sulfide inclusions in lherzolitic Cr-pyropes from Upper Muna kimberlites have been determined by laser ablation MCICPMS. Most analysed sulfides (~92%) have very low Re/Os ratios (<0.07), and their Re-depletion ages (TRD) form three major peaks: 3.4-2.8, 2.2-1.8 and 1.4-1.2 Ga (±0.03 Ga, mean 2s analytical uncertainty). One sulfide give the oldest TRD age at 4 Ga. Our data suggest that refertilization of the highly depleted SCLM and the introduction of Cr-pyrope garnet occurred in several episodes. The oldest age of ca 4 Ga indicate on the beginning of the formation of the depleted SCLM of the Siberian Craton in Hadean time [2].
DS1859-0021
1809
Pearson, R.Hutton, C., Shaw, G., Pearson, R.A Description of the Diamond Mines As It Was Presented by The Earl Marshal of England to the Royal Society.Phil. Transactions Royal Society of London., Vol. 2, FROM 1672-1683, No. 136, PP. 405-411.India, Golconda, Borneo, Minas GeraisHistory
DS1991-1318
1991
Pearson, R.C.Pearson, R.C.Maps showing mineral resource assessment for placer gold and silver DillonQuad.Idaho and MontanaUnited States Geological Survey (USGS) Map, No. I-1803-F, 1: 250, 000 $ 3.10Idaho, MontanaPlacers, Map
DS1900-0793
1909
Pearson, S.Pearson, S.American Diamonds. #2South African Mining Journal, Vol. 7, PT. 1, JUNE 12TH. P. 412.United States, Gulf Coast, Arkansas, Pennsylvania, Appalachia, KentuckyDiamond Occurrences
DS1910-0079
1910
Pearson, S.Pearson, S.Origin of Diamonds of German Southwest AfricaMining Engineering Journal of South Africa, Vol. 7, PT. 2, No. 365, MARCH 5TH. P. 680.Southwest Africa, NamibiaDiamond Genesis
DS201212-0361
2012
Pearson, S.Kjarsgaard, B.A., Mather, D.G., Pearson, S., Jackson, D., Crabtree, D., Creighton, S.CR-diopside and Cr-pyrope xenocryst thermobarometry revisited: applications to lithosphere studies and diamond exploration.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractCanadaGeobarometry
DS1982-0211
1982
Pearson, W.N.D.Franklin, J.M., Pearson, W.N.D.Metallogeny of the Keweenawan (mid Continent) Rift Zone in The Lake Superior Region.Geological Association of Canada (GAC), Vol. 7, P. 50. (abstract.).GlobalMid-continent
DS1996-0934
1996
Pease, T.C.McLemore, V.T., Lueth, V.W., Pease, T.C., Guilinger, J.R.Petrology and mineral resources of the Wind River laccolith, CornudasMountains, New Mexico and TexasCanadian Mineralogist, Vol. 34, pt. 2, April pp. 335-348.New Mexico, TexasAlkaline rocks
DS2003-1052
2003
Pease, V.Pease, V.Rodinia's Baltica: internal structure and marginsGeological Society of America, Annual Meeting Nov. 2-5, Abstracts p.343.Scandinavia, Poland, Ukraine, BalticaTectonics
DS200412-1512
2003
Pease, V.Pease, V.Rodinia's Baltica: internal structure and margins.Geological Society of America, Annual Meeting Nov. 2-5, Abstracts p.343.Europe, Scandinavia, Baltic ShieldTectonics
DS200512-0321
2005
Pease, V.Gee, D.G., Pease, V.The Neoproterozoic Timanide Orogen of eastern Baltica.Geological Society of London, Memoir M0030 160p.Baltic Shield, Norway, Finland, RussiaBook - East European Craton, subduction
DS200812-0237
2008
Pease, V.Condie, K.C., Pease, V.When did plate tectonics begin on Earth?Geological Society of America Special Paper, 440, 290p. $ 85.00MantleBook - tectonics
DS200812-0871
2008
Pease, V.Pease, V., Percival, J., Smithies, H., Stevens, G., Van Kramendonk, M.When did plate tectonics begin? Evidence from the orogenic record.Geological Society of America Special Paper, 440, pp. 199-228.MantleTectonics
DS1989-1187
1989
Peat MarwickPeat MarwickThe Canadian exploration incentive program (CEIP) and the new flow through share regimePeat Marwick, 2p. brief summary Database # 17611CanadaEconomics, CEIP flow through
DS1988-0294
1988
Peate, D.Hawkesworth, C.J., Mantovani, M., Peate, D.Lithospheric remobilization during Parana CFB magmatismJournal of Petrology, Special Volume 1988- Oceanic and Continental, pp. 205-224Brazil, Paraguay, ArgentinaMantle, Chemistry
DS200612-1062
2006
Peate, D.Peate, D., Kerr, A.Plumes and large igneous provinces.Goldschmidt Conference 16th. Annual, S4-08 theme abstract 1/8p. goldschmidt2006.orgMantleHotspots, plumes
DS1989-1298
1989
Peate, D.W.Rogers, N.W., Ellam, R.M., Peate, D.W., Hawkesworth, C.J.Potassic mafic rocks from the Virunga and the Karoo and the composition Of the subcontinental mantleNew Mexico Bureau of Mines Bulletin., Continental Magmatism Abstract Volume, Held, Bulletin. No. 131, p. 225 Abstract held June 25-July 1Central AfricaTectonics, Rift
DS1993-1209
1993
Peate, D.W.Peate, D.W., Hawkesworth, C.J, Mantovani, M.SM.Chemical stratigraphy of the Parana lavas (South America): classification of magma types and their spatial distributionBulletin Volcanology, Vol. 55, pp. 119-139South AmericaFlood basalts, Geochemistry
DS1995-1453
1995
Peate, D.W.Pearce, J.A., Peate, D.W.Tectonic implications of the composition of volcanic arc magmasAnnual Review of Earth Planetary Sciences, Vol. 23, pp. 251-286MantleTectonics, Magmas - arc
DS1996-1090
1996
Peate, D.W.Peate, D.W., Hawkesworth, C.J.Lithospheric to asthenospheric transition in low Ti flood basalts From southern Parana, BrasilChemical Geology, Vol. 127, No. 1-3, Jan. 10, pp. 1-24BrazilBasalts, Xenoliths, Geochemistry
DS2000-0503
2000
Peate, D.W.Kirstein, L.A., Peate, D.W., Mantovani, M.S.M.Early Cretaceous basaltic and rhyolitic magmatism in southern Uruguay: associated opening South AtlanticJournal of Petrology, Vol. 41, No. 9, Sept. pp. 1413-38.Uruguay, South AmericaMagmatism
DS2003-1053
2003
Peate, D.W.Peate, D.W., Techer, O.Pb isotope evidence for contributions from different Iceland mantle components toLithos, Vol. 67, No. 1-2, March pp. 39-52.IcelandGeochornology - Blooseville Kyst area, Iceland plume
DS200412-1513
2004
Peate, D.W.Peate, D.W., Baker, J.A., Breddam, K., Waight, T.E., Skovgaard, A.C., Stecher, O., Prestvik, T., JonassonPb isotope heterogeneity of the mantle beneath Iceland.Geochimica et Cosmochimica Acta, 13th Goldschmidt Conference held Copenhagen Denmark, Vol. 68, 11 Supp. July, ABSTRACT p.A569.Europe, IcelandGeochronology
DS200512-0833
2005
Peate, D.W.Peate, D.W., Hawkesworth, C.J.U series disequilibria: insights into mantle melting and the timescales of magma differentiation.Reviews of Geophysics, Vol. 43, 1, March 31, RG 1003MantleMelt, metasomatism
DS200712-0824
2006
Peate, D.W.Peate, D.W., Breddam, K., Baker, J.A., Kurz, M., Grassineau, N., Barker, A.K.Compositional features of enriched Icelandic mantle components.Geochimica et Cosmochimica Acta, In press availableEurope, IcelandGeochemistry
DS201012-0571
2010
Peats, J.Peats, J., Stachel, T., Stern, R., Muehlenbachs, K., Armstrong, J.Aviat diamonds as a window into the deep lithospheric mantle beneath the northern Churchill province.38th. Geoscience Forum Northwest Territories, Abstract pp.118-119.Canada, Northwest Territories, Melville PeninsulaGeochronology - nitrogen, CI
DS201212-0547
2012
Peats, J.Peats, J., Stachel, T., Ster, R.A., Muehlenbachs, K., Armstrong, J.Aviat diamonds: a window into the deep lithospheric mantle beneath the Northern Churchill Province, Melville Peninsula, Canada.Canadian Mineralogist, Vol. 50, 3, June pp. 611-624.Canada, Nunavut, Melville PeninsulaDeposit - Aviat
DS1998-1141
1998
Pebesma, E.J.Pebesma, E.J., Wesseling, C.G.GSTAT: a program for geostatistical modelling, prediction and simulationComputers and Geosciences, Vol.24, No. 1, pp. 17-31GlobalGeostatistics, Kriging, Computer - program, GSTAT.
DS200812-0345
2008
PeccerilloFerrnado, S., Frezzotti, M.L., Neumann, De Astis, Peccerillo, Dereje, Gezahegn, TeklewoldComposition and thermal structure of the lithosphere beneath the Ethiopian plateau: evidence from mantle xenoliths in basanites, Injibara Lake Tana Province.Mineralogy and Petrology, Vol. 93, 1-2, pp. 47-78.Africa, EthiopiaBasanites, Foidites
DS1985-0521
1985
Peccerillo, A.Peccerillo, A., Giampiero, P.Primary Potassic Magmas in the Roman Province: Condition Of genesis and Geodynamic Implications.Geological Association of Canada (GAC)., Vol. 10, P. A47, (abstract.).ItalyBlank
DS1987-0221
1987
Peccerillo, A.Francalanci, L., Peccerillo, A., Poli, G.Partition coefficients for minerals in potassium alkaline rocks: dat a from Roman province (Central Italy)Geochemical Journal, Vol. 21, No. 1, pp. 1-10ItalyAlkaline rocks, Analyses
DS1988-0537
1988
Peccerillo, A.Peccerillo, A., Poli, G., Serri, G.Petrogenesis of oreniditic and kamafugitic rocks from central ItalyCanadian Mineralogist, Vol. 26, No. 1, March pp. 23-44ItalyBlank
DS1989-0287
1989
Peccerillo, A.Conticelli, S., Peccerillo, A.Petrological significance of high-pressure ultramafic xenoliths from ultrapotassic rocks of central Italy #1New Mexico Bureau of Mines Bulletin., Continental Magmatism Abstract, Bulletin. No. 131, p. 58. AbstractItalyXenoliths
DS1989-1188
1989
Peccerillo, A.Peccerillo, A., Conticelli, S.Lamproitic to Roman type ultrapotassic magmatism In central Italy; petrological, geochemical and isotopicvariationsNew Mexico Bureau of Mines Bulletin., Continental Magmatism Abstract Volume, Held, Bulletin. No. 131, p. 211. AbstractItalyLamproite
DS1990-0356
1990
Peccerillo, A.Conticelli, S., Peccerillo, A.Petrological significance of high-pressure ultramafic xenoliths from ultrapotassic rocks of Central Italy #2Lithos, Vol. 24, No. 4, August pp. 305-322ItalyUltrapotassic rocks, Petrology, Xenoliths
DS1990-1167
1990
Peccerillo, A.Peccerillo, A., Conticelli, S.Petrology and geochemistry of high pressure ultramafic xenoliths from ultrapotassic rocks of central ItalyTerra, Abstracts of International Workshop Orogenic Lherzolites and Mantle Processes, Vol. 2, December abstracts p. 139ItalyAlkaline -ultrapotassic, Lherzolites, Harzburgites
DS1992-0296
1992
Peccerillo, A.Conticelli, S., Peccerillo, A.Petrology and geochemistry of potassic and ultrapotassic volcanism In central Italy -petrogenesis and inferences on the evolution of the mantlesourcesLithos, Vol. 28, No. 3-6. November pp. 221-240ItalyPetrology, geochemistry, Ultrapotassic
DS1993-1210
1993
Peccerillo, A.Peccerillo, A.Potassic and ultrapotassic rocks: compositional characteristics, petrogenesis and geologic significance.Episodes, Vol. 15, No. 4, December 1992, pp. 243-251.GlobalPetrology, Potassic rocks
DS1994-0508
1994
Peccerillo, A.Federico, M., Peccerillo, A., et al.Mineralization and geochem. study granular xenoliths from Alban Hillsvolcano, Italy: an evolutionary processes in potassic magma.Contr. Mineralogy and Petrology, Vol. 116, No. 3, pp. 384-401.ItalyAlkaline rocks, Xenoliths
DS1994-1350
1994
Peccerillo, A.Peccerillo, A.calc alkaline to ultrapotassic magmatism: constraints on mantle type of metasomatism and meltingInternational Symposium Upper Mantle, Aug. 14-19, 1994, pp. 100-102.ItalyAlkaline rocks, Metasomatism
DS1995-1466
1995
Peccerillo, A.Peccerillo, A., Ferraro, C., Gezaegn, Y.Petrogenesis of peralkaline acid magmas along the main Ethiopian RiftGeological Society Africa 10th. Conference Oct. Nairobi, p. 117. Abstract.GlobalAlkaline rocks, Petrology
DS1998-1142
1998
Peccerillo, A.Peccerillo, A.Relationships between ultrapotassic and carbonate rich volcanic rocks central Italy: petrogenetic, geodynamicLithos, Vol. 43, No. 4, Sept. pp. 267-ItalyAlkaline rocks
DS1999-0546
1999
Peccerillo, A.Peccerillo, A.Multiple mantle metasomatism in central southern Italy: geochemicaleffects, timing and geodynamic implicationsGeology, Vol. 27, No. 4, Apr pp. 315-8.ItalyLamproites, Magmatism, Metasomatism
DS200512-0850
2005
Peccerillo, A.Petrilli, M., Poli, G., Perugini, D., Peccerillo, A.PetroGraph: a new software to visualize, model, and present geochemical dat a in igneous petrology.Geochemistry, Geophysics, Geosystems: G3, Vol. 6, doi. 10.1029/2005 GC000932TechnologyComputer - program, PetroGraph, major, trace elements
DS200612-1063
2006
Peccerillo, A.Peccerillo, A., Martinotti, G.The western Mediterranean lamproitic magmatism: origin and geodynamic significance.Terra Nova, Vol. 18, 2, April pp. 109-117.EuropeMagmatism - lamproite
DS200712-0329
2007
Peccerillo, A.Frezzotti, M-L., Peccerillo, A.Diamond bearing COHS fluids in the mantle below Hawaii.Earth and Planetary Science Letters, Vol. 262, 1-2, pp. 273-283.MantleDiamond - fluidization
DS200812-0872
2007
Peccerillo, A.Peccerillo, A.Mantle plumes vs subduction related origin of volcanism in Italy: a commentary.Vladykin Volume 2007, pp. 57-70.Europe, ItalySubduction
DS2002-1356
2002
PecherRolland, Y., Picard, C., Pecher, Lapierre, Bosch, KellerThe Cretaceous Ladakh arc of NW Himalaya slab melting and melt mantle interaction during fast northward driftChemical Geology, Vol.182, 2-4, Feb.15, pp.139-78.India, northwest HimalayasMelting, slab subduction, Indian Plate
DS1993-1438
1993
Pechersk, D.M.Sharonova. Z.V., Pechersk, D.M., Spetsius, Z.V.Paleomagnetic examination of the serpentinization stage of kimberlites and xenoliths from the Udachnaya pipe.(Russian)Fizik Zemli, (Russian), No. 4, April pp. 69-75.Russia, YakutiaGeophysics, paleomagnetics, Deposit -Udachnaya
DS1987-0079
1987
Pecherskii, D.M.Brodskaya, S.Yu., Pecherskii, D.M., Epshtein, E.M.Temperature related evolution of ferrospinels of ultramafic rocks and carbonatites based on petromagnetic and mineralogical studies.(Russian)Izv. Akad. Nauk SSSR Fiz. Zemli, (Russian), No. 10, pp. 66-78RussiaCarbonatite
DS1960-0587
1965
Pecherskii, V.P.Pecherskii, V.P.On the Discovery of Micaceous Kimberlites in the Foothills Of the Eastern Sayan.Sovetsk. Geol., Vol. 4, PP. 131-133.RussiaBlank
DS1991-1319
1991
Pecherskiy, D.M.Pecherskiy, D.M.About paleomagnetism of bottom layers of the continental earthcrust.(Russian)I.a.n. Sss Geo., (russian), No. 9, September pp. 66-78. #HG089RussiaGeophysics, Paleomagnetics Mantle
DS2001-0898
2001
Pechersky, D.M.Pechersky, D.M., Genshaft, Yu.S.Paleomagnetism of the continental lithosphere and the origin of regional magnetic anomalies: review.Russian Journal of Earth Science, Vol. 3, 2, May, pp.MantleGeophysics - magnetics
DS1995-1065
1995
Pechniko, V.A.Lavrova, L.D., Pechniko, V.A., Petrova, M.A., Ekimova, T.E.Minerals - indicators of diamond in the metamorphic rocks. (Russian)Doklady Academy of Sciences Nauk, (Russian), Vol. 343, No. 2, July pp. 220-224.Russiametamorphism
DS1993-1211
1993
Pechnikov, V.A.Pechnikov, V.A., Bobrov, V.A., Podkuyko, A.Isotopic compositions of diamond and accompanying graphite in north Kazakstan metamorphic rocks.Geochemistry International, Vol. 30, No. 8, pp. 153-157.Russia, KazakhstanGeochronology, Diamond morphology
DS1993-1212
1993
Pechnikov, V.A.Pechnikov, V.A., Bobrov, V.A., Popdkuyko, Yu.A.Isotope composition of diamond and accompanying graphite from metamorphic rocks of northern Kazakhstan.(Russian)Geochemistry International (Geokhimiya), (Russian), Vol. 1993, No. 1, pp. 150-154.Russia, Kazakhstan, Commonwealth of Independent States (CIS)Geochronology, Diamond
DS1995-1467
1995
Pechnikov, V.A.Pechnikov, V.A., Ekimova, T.E.The origin of microdiamond deposits in metamorphic complexesSga Third Biennial Meeting, Aug. 1995, pp. 621-624.RussiaKotchetkav Massif, Metamorphic complexes
DS200812-0873
2008
Pechnikov, V.A.Pechnikov, V.A., Kaminsky, F.V.Diamond potential of metamorphic rocks in the Kochetav Massif, northern Kazakhstan.European Journal of Mineralogy, Vol. 20, no. 3, pp. 395-413.Russia, KazakhstanMetamorphic - diamond
DS201012-0173
2010
Pechnikov, V.A.Dubinchuk, V.T., Simakov, S.K., Pechnikov, V.A.Lonsdaleite in diamond bearing metamorphic rocks of the Kokchetav massif.Doklady Earth Sciences, Vol. 430, 1, pp. 40-42.RussiaUHP Mineralogy
DS201112-0775
2011
Pechnikov, V.A.Pechnikov, V.A., Kaminsky, F.V.Structural and microstructual regularities of the distribution of diamond in metamorphic rocks of the Kumdy-Kol and Barchi-Kol deposits, Kokchetav Massif, Northern Kazakhstan.The Canadian Mineralogist, Vol. 49, 3, pp. 673-690.Russia, KazakhstanDiamond morphology - Kokchetav
DS2001-0452
2001
PeckHarris, M.J., Symons, D.T.A., Peck, Blackburn, TurekDevelopments in the 2.1 to 1.7 Ga apparent polar wander path for the Trans-Hudson Orogen and Superior Craton.Geological Association of Canada (GAC) Annual Meeting Abstracts, Vol. 26, p.59, abstract.Manitoba, SaskatchewanTrans Hudson Orogen, Tectonics
DS1991-1320
1991
Peck, D.C.Peck, D.C., James, R.S.Geology and platinum group element sulphide mineralization, East BulletinLakeOntario Geological Survey Open File, Report No. 5813, 65pOntarioPlatinuM., Deposit -East Bulletin Lake
DS1995-0318
1995
Peck, D.C.Chubb, P.T., Peck, D.C., James, R.S., Ercit, T.S.Nature and origin of nodular textures in anorthositic cumulates from the east Bulletin intrusion, OntarioMineralogy and Petrology, Vol. 54, No. 1-2, pp. 93-104OntarioAnorthosites, layered intrusion, Deposit -East Bulletin
DS1997-0559
1997
Peck, D.C.Jobin-Bevans, L.S., Halden, N.M., Peck, D.C., CameronGeology and oxide mineralization of the Pipe stone Lake anorthosite ManitobaExploration and Mining Geology, Vol. 6, No. 1, pp. 35-61ManitobaTitanium, Vanadium, rare earths, Deposit - Pipestone Lake
DS1996-1091
1996
Peck, W.H.Peck, W.H., Valley, J.W.The Fisken asset anorthosite complex: stable isotope evidence for shallow emplacement -Archean ocean crustGeology, Vol. 24, No. 6, June pp. 523-526GreenlandGeochronology, Anorthosite -Fiskenaesset
DS2001-0899
2001
Peck, W.H.Peck, W.H., Valley, J.W., Wilde, S.A., Graham, C.M.Oxygen isotope ratios and rare earth elements in 3.3 - 4.4 Ga zircons: ion microprobe evidence high 0 18...Geochimica et Cosmochimica Acta, Vol. 65, No. 22, pp. 4215-29.AustraliaGeochronology, Craton - Yilgarn
DS2002-1635
2002
Peck, W.H.Valley, J.W., Peck, W.H., King, E.M., Wilde, S.A.A cool early EarthGeology, Vol. 30,4,Apr.pp.351-4.MantleArchean - geochronology, impacts, meteorites
DS201911-2526
2019
Peckmann, J.Giampouras, M., Garrido, C.J., Zwicker, J., Vadillo, I., Smrzka, D., Bach, W., Peckmann, J., Jemenez, P., Benavente, J., Garcia-Ruiz, J.M.Geochemistry and mineralogy of serpentinization driven hyperalkaline springs in the Ronda peridotite.Lithos, doi 10.1016/j.lithos.2019.105215, 75p. PdfEurope, Spaindeposit - Ronda

Abstract: We present a detailed study of the water geochemistry, mineralogy and textures in serpentinization-related hyperalkaline springs in the Ronda peridotites. Ronda waters can be classified into hyperalkaline fluids and river waters that are broadly similar to Ca2+-OH- and Mg2+-HCO3- water types described in serpentinite-hosted alkaline springs elsewhere. At the discharge sites of the fluids (fractures or human made outlets) and ponds along the fluid flow paths, the fluids are hyperalkaline (10.9 < pH < 12) and characterized by low Mg and high Na, K, Ca, and Cl concentrations. River waters, occurring near the spring sites, are mildly alkaline (8.5 < pH < 8.9) and enriched in Mg and DIC compared to Na, K, Ca and Cl. The chemistry of Ronda Mg-HCO3 river waters is likely due to the hydrolysis of ferromagnesian peridotite minerals in equilibrium with the atmosphere by infiltrated meteoric water and shallow groundwater in the serpentinized peridotite. The Ronda Ca-OH hyperalkaline fluids are generated by the combination of low temperature serpentinization reactions from infiltrated surface Mg-HCO3 river waters —or Ca-HCO3 waters from near karst aquifers— and deep carbonate precipitation isolated from atmospheric CO2. Mass balance calculations indicate that the weathering of Ca-bearing peridotite silicates such as diopside is a feasible source of Ca in Ronda Ca-OH hyperalkaline fluids; however, it requires steady-state dissolution rates substantially greater than those determined experimentally. Travertine, crystalline crusts and sediment deposits are the main types of solid precipitates observed in Ronda hyperalkaline spring sites. Calcite and aragonite, minor dolomite and Mg-Al-rich clays are the main minerals in the spring sites. As illustrated in the Baños del Puerto spring site, (i) calcite-dominated precipitation is due to hyperalkaline fluid uptake of atmospheric CO2 during discharge, and (ii) aragonite-dominated precipitation is due to mixing of Ca-OH hyperalkaline fluids with Mg- HCO3 river waters. Aragonite and dolomite contents increase away from the springs and toward the river waters that uniquely reflects the effect of Mg ions on the precipitation of aragonite versus calcite. Other potential factors controlling the precipitation of these CaCO3 polymorphs are the Mg/Ca ratio, the CO2 content, and the temperature of the fluids. Dolomite forms during lithification of travertine due to periodic flooding of river water combined with subsequent evaporation.
DS1960-0287
1962
Pecora, W.T.Pecora, W.T.Carbonatite Problem in the Bearpaw Mountains, MontanaGeological Society of America (GSA) SPECIAL VOLUME, PETROLOGIC STUDIES: A VOLUM, PP. 83- 104.MontanaKimberlite, Rocky Mountains
DS1988-0538
1988
Pecover, S.R.Pecover, S.R.Cainozoic maar volcanism and the origin of sapphire and possible diamond In eastern AustraliaGeological Society of Australia Ninth Australian Geological Conference Achievements in, pp. 314-315. AbstractAustraliaDiamond genesis -brief
DS2001-1048
2001
PecskaySeghedi, I., Downes, H., Pecskay, Thirlwall, Szakacsmagma genesis in a subduction related post collisional volcanic arc segment: the Ukrainian Carpathians.Lithos, Vol. 57, No. 4, July, pp. 237-62.UKraineAlkaline magmatism, Subduction - not specific to diamonds
DS200812-1033
2008
Pecskay, Z.Seghedi, I., Ntaflos, T., Pecskay, Z.The Gataia Pleistocene lamproite: a new occurrence at the southeastern edge of the Pannonian Basin, Romania.Geological Society of London, Special Publications no. 293, pp.83-100.Europe, RomaniaLamproite
DS201709-2047
2017
Pecskay, Z.Rapprich, V., Pecskay, Z., Magna, T., Mikova, J.Age disparity for spatially related Sevattur and Samalpatti carbonatite complexes.Goldschmidt Conference, abstract 1p.Indiacarbonatites

Abstract: The Neoproterozoic Sevattur and Samalpatti alkaline– carbonatite complexes in S India were supposedly emplaced into regional metagranite at ~800 Ma [1]. Both complexes are close to each other (~4 km apart), with a similar NE–SW elongated oval shape arranged along NE–SW trending lineament formed by the Koratti–Attur tectonic zone [2]. Both complexes share a similar setting with central syenite intrusion mantled with a discontinuous ring and/or crescentshaped suites of carbonatites, pyroxenites, gabbros, and dunites. In contrast to identical tectonic position and similar structure, the two complexes differ significantly in geochemistry and Sr–Nd–Pb–O–C isotope compositions. The Sevattur suite is derived from an enriched mantle source without significant post-emplacement modification whilst extensive hydrothermal overprint by crustal fluids must have occurred to result in the observed 13C–18O-enriched systematics reported for the Samalpatti carbonatites [3]. Some Samalpatti pyroxenites, though, show a clear mantle signature [3]. We report preliminary K–Ar age-data, that indicate a prolonged period of the magmatic activity in this area. Sevattur gabbro and pyroxenite (both Bt-fraction) as well as one Samalpatti Cr-rich silicocarbonatite (Amp-fraction) yielded the range of ages at 700–800 Ma, consistent with previous reports [see 3 for details]. The new K–Ar data from syenites display significantly younger ages of 560–576 Ma for Samalpatti and 510–540 Ma for Sevattur, regardless of the mineral fraction used (Bt or Kfs). The K–Ar results are being supplemented by systematic U–Pb analyses of zircons. If proven true, the age disparity would have profound consequences on our understanding of carbonatite evolution.
DS201801-0035
2017
Pecskay, Z.Magna, T., Rapprich, V., Wittke, A., Gussone, N., Upadhyay, D., Mikova, J., Pecskay, Z.Calcium isotope systematics and K-Ar and U-Pb temporal constraints on the genesis of Sevattur Samalpatti carbonatite silicate alkaline complexes.Carbonatite-alkaline rocks and associated mineral deposits , Dec. 8-11, abstract p. 34-35.Indiadeposit - Samalpatti, Sevattur

Abstract: We present the first systematic survey of Ca isotope compositions in carbonatites and associated silicate rocks from Samalpatti and Sevattur, two Neoproterozoic complexes in Tamil Nadu, south India. Despite their close geographic proximity, their genesis and post-emplacement histories differ (Ackerman et al. 2017). The Sevattur complex appears to have been derived from an enriched mantle source with a limited post-magmatic disturbance. In contrast, carbonatites from Samalpatti show a record of extensive late-stage post-magmatic overprint, also apparent from unusually heavy C-O isotope compositions in a sub-suite of carbonatites (Ackerman et al. 2017). The mean ?44/40Ca = 0.69 ± 0.10‰ is slightly lighter than the average of fertile, unmetasomatized peridotites at ?44/40Ca = 0.95 ± 0.05‰ (Kang et al. 2017). This difference may attest to the general difference between carbonates and silicates (see Kang et al. 2017). It could also reflect Ca isotope fractionation between isotopically heavy silicate and isotopically light carbonate (e.g., John et al. 2012), though to a somewhat minor extent. This is supported by leaching experiments in this study where the extent of silicate-carbonate fractionation (44/40Casilicate-carbonate) has been investigated. The values at ~0.1-0.2‰ are expectedly lower than those reported earlier (~0.6‰; John et al. 2012) and may reflect high-temperature Ca isotope fractionation. The variability in ?44/40Ca values of carbonatites and silico-carbonatites from the Samalpatti complex is larger (0.70- 1.14‰) and appears to be in accord with extensive post-emplacement disturbance. Significant loss of REE and 13C-18O-enriched signature are combined with high ?44/40Ca values, which could reflect massive exchange with metasomatic aqueous fluids. The 40Kdecay correction was applied to K-rich rocks (syenites, monzonites). Given the antiquity of the complex dated at ca. ~800 Ma (Schleicher et al. 1997) and considering high-K/Ca character of some rocks, the resulting ?44/40Ca800 Myr correction was up to ~+1.2‰. In this regard, it is crucial to constrain the age history of the entire region. The nearby Hogenakal carbonatite body was dated at ~2.4 Ga which is much older than Rb-Sr and Sm-Nd age of Sevattur (Kumar et al. 1998) from the same fault system. We have acquired K-Ar mineral (K-feldspar, biotite, amphibole) and U-Pb zircon data from Sevattur and Samalpatti. The K-Ar ages span a range between ~800 and ~510 Ma (~800 Ma for amphiboles and biotites from silico-carbonatites and mafic silicate rocks and ~570-510 Ma for K-feldspars and biotites from syenites), dating two high-grade regional tectono-thermal overprint events, documented earlier. The complex nature of this process is indicated by concordant U-Pb zircon age at ~2.5 Ga yielded for a melatonalite, for which K-Ar biotite age of ~802 Ma was measured. This fits into the age bracket of basement of the Eastern Dharwar Craton. The age distribution bimodality at ~2.5 Ga and ~800 Ma has been found for several other samples, suggesting a pulsed thermal history of the area, associated with a significant overprint by fluids likely derived from the local crust. Particularly high U concentrations in zircons (thousands ppm), combined with a range of K-Ar ages, attest to such multi-episodic history.
DS1992-1178
1992
Peddie, N.W.Peddie, N.W.The magnetic field in the United States 1990 -declination chartUnited States Geological Survey (USGS) Map, GP 1002-D, 1" 55miles $ 3.75United StatesGeophysics, Magnetic declination chart
DS1990-1168
1990
Peddle, D.R.Peddle, D.R., Franklin, S.E.GEODEMON - a Fortran 77 program for restoration and derivative processing of digital image dataComputers and Geosciences, Vol. 16, No. 5, pp. 669-696GlobalComputers, Program -GEODEMON.
DS1991-0509
1991
Peddle, D.R.Franklin, S.E., Peddle, D.R., Wilson, B.A., Blodgett, C.F.Pixel sampling of remotely sensed digital imageryComputers and Geosciences, Vol. 17, No. 6, pp. 759-776GlobalComputers, Remote sensing
DS2001-0900
2001
Peddle, D.R.Peddle, D.R., White, H.P., Soffer, R.J., Miller, J.R.Reflectance processing of remote sensing spectroradiometer dataComp. and Geosciences, Vol. 27, No. 2, pp. 203-13.GlobalRemote sensing - reflectance, Program - BOREAS not specific to diamonds
DS1984-0651
1984
Peddy, C.Serpa, L., Setzer, T., Farmer, H., Peddy, C., Brown, L., Oliver, J.Cocorp Profiling Across the Midcontinent Gravity HighGeological Society of America (GSA), Vol. 16, No. 2, FEBRUARY P. 113. (abstract.).GlobalMid-continent
DS200412-0406
2004
PedeDarbyshire, F.A., Larsen, T.B., Mosegaard, K., Dahl Jensen, T., Gudmundsson, O., Bach, T., Gregersen, S., PedeA first detailed look at the Greenland lithosphere and upper mantle; using Rayleigh wave tomography.Geophysical Journal International, Vol. 158, 1, pp. 267-286.Europe, GreenlandGeophysics - seismic
DS1994-0408
1994
Pedeira, A.De Medeiros Delgado, I., Pedeira, A., Thorman, C.H.Geology and mineral resources of Brasil: a reviewInternational Geology Review, Vol. 36, No. 6, June pp. 503-544.BrazilReview, Mineral resources
DS200912-0147
2009
Pedeira, A.J.Danderfer, A., De Waele, B., Pedeira, A.J., Nalini, H.A.New geochronological constraints on the geological evolution of Espinhaco basin within the San Francisco Craton- Brazil.Precambrian Research, Vol. 170, 1-2, pp. 116-128.South America, BrazilGeochronology - not specific to diamonds
DS1992-0567
1992
Pedersen, A.K.Gill, R.C.O., Pedersen, A.K., Larsen, J.G.Tertiary picrites in West Greenland: melting at the periphery of a plume?Geological Society Special Publication, Magmatism and the Causes of Continental, No. 68, pp. 335-348GreenlandPicrites, Plume
DS1992-0721
1992
Pedersen, A.K.Holm, P.M., Gill, R.C.O., Pedersen, A.K., Larsen, J.G., Hald, N.The Icelandic mantle plume: compositional constraints from the West Greenland Tertiary picritesEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p.336GreenlandPicrites, Mantle plume
DS1993-0379
1993
Pedersen, A.K.Dueholm, K.S., Garde, m A.A., Pedersen, A.K.Preparation of accurate geological and structural maps, cross sections orb lock diagrams from colour slides, using multi-model photogrammetryJournal of Structural Geology, Vol. 15, No. 7, pp. 933-937GlobalStructure, Maps, slides
DS1993-0694
1993
Pedersen, A.K.Holm, P.M., Gill, R.C.O., Pedersen, A.K., Larsen, J.G., Hald, N.The Tertiary picrites of West Greenland: contributions from Icelandic and other sourcesEarth and Planetary Science Letters, Vol. 115, No. 1-4, March pp. 227-244GreenlandPicrites, Alkaline rocks
DS2000-0551
2000
Pedersen, A.K.Larsen, L.M., Pedersen, A.K.Processes in high magnesium, high 7 magmas: evidence from olivine, chromite and glass in Palaeogene picrites.Journal of Petrology, Vol. 41, No. 7, July pp.1071-98.GreenlandPicrites
DS2003-0774
2003
Pedersen, A.K.Larsen, L.M., Pedersen, A.K., Sundvoll, B., Frei, R.Alkali picrites formed by melting of old metasomatized lithospheric mantle: ManitdlatJournal of Petrology, Vol. 44, 1, pp. 3-38.GreenlandPicrites
DS2003-1163
2003
Pedersen, A.K.Riisager, J., Riisager, P., Pedersen, A.K.Paleomagnetism of large igneous provinces: a case study from West Greenland, NorthEarth and Planetary Science Letters, Vol. 214, 3-4, pp. 409-425.GreenlandGeophysics - magnetics, alkaline
DS200412-1667
2003
Pedersen, A.K.Riisager, J., Riisager, P., Pedersen, A.K.Paleomagnetism of large igneous provinces: a case study from West Greenland, North Atlantic igneous province.Earth and Planetary Science Letters, Vol. 214, 3-4, pp. 409-425.Europe, GreenlandGeophysics - magnetics, alkaline
DS200412-1932
2004
Pedersen, A.K.Storey, M., Pedersen, A.K., Stecher, O., Bernstein, S., Larsen, H.C., Larsen, L.M., Baker, Duncan, R.A.Long lived post breakup magmatism along the East Greenland margin: evidence for shallow mantle metasomatism by the Iceland plumeGeology, Vol. 32, 2, Feb. pp. 173-176.Europe, Greenland, IcelandMagmatism
DS201012-0424
2009
Pedersen, A.K.Larsen, L.M., Pedersen, A.K.Petrology of the Paleocene picrites and flood basalts on Disko and Nuussuaq, West GreenlandJournal of Petrology, Vol. 50,9, pp. 1667-1711.Europe, GreenlandPicrite
DS201212-0294
2012
Pedersen, B.oC.Henning, O.,Sorensen, S.S., Hakin, S., Pedersen, B.oC., Christiansen, Z.I.Non destructive identification of micrometer scale minerals and their position within a bulk sample.Canadian Mineralogist, Vol. 50, 2, pp. 501-509.TechnologyMicrotomography
DS202201-0032
2021
Pedersen, C.Pedersen, C.Geology and mining of the Nechalacho rare earth deposits, Thor Lake, Northwest Territories.NWTgeoscience.ca, 1p. AbstractCanada, Northwest TerritoriesREE

Abstract: Cheetah’s Nechalacho rare earth deposits are located at Thor Lake, 110 kms southeast of Yellowknife, 8 kms north shore of the Hearne Channel on Great Slave Lake. The two principal deposits are the North T deposit, the focus of the current Stage 1 rare earth mining program, and the Nechalacho Tardiff deposit currently in the planning stages for Stage 2 mining. The North T deposit, at 101,000 tonnes grading 9.01% TREO, consists of a 4-metre thick layer of the light rare earth (LREE) mineral bastnaesite, which occurs in coarse grained to massive aggregates in a gangue of pure quartz. The ellipsoidal sub-zone is one of several concentric mineralogically-distinct zones in the ovoid North-T deposit, which is approximately 150 metres in diameter and 150 metres in depth. The bastnaesite sub-zone crops out on surface and dips inward before flattening out in the centre at an average depth of 30 metres. Open-cast extraction commenced in June of 2021, providing feed-stock ore which was processed by XRT sensor-based ore sorting technology which produced a high-grade bastnaesite concentrate for shipment to Hay River and ultimately to Cheetah’s Saskatoon will facility. Stage 2 will see the development of the much larger Tardiff deposit, one of several high-grade LREE sub-zones in the 94.7 million tonnes Nechalacho deposit. The mineralogy is similar to the North T deposit, consisting primarily of bastnaesite, with sub-ordinate REE minerals monazite and allanite. Cheetah has off-take agreements with the Norwegian firm REEtec for Stage 1 production of 1000 tonnes REE (ex-Ce)/year for an initial 5-year period, and an MOU with UCore Rare Metals Inc to supply rare-earth concentrate to their planned separation facility in Alaska.
DS201312-0088
2013
Pedersen, H.Bou, P., Poli, P., Campillo, M., Pedersen, H., Briand, X., Roux, P.Teleseismic correlations of ambient seismic noise for deep global imaging of the Earth.Geophysical Journal International, Vol. 194, 2, pp. 844-848.MantleGeophysics - seismics
DS200412-0231
2004
Pedersen, H.A.Bruneton, M., Pedersen, H.A., Vacher, P., Kukkonenen, I.T., Arndt, N.T., Funke, S., Friederich, W., Farra, V.Layered lithospheric mantle in the central Baltic Shield from surface waves and xenolith analysis.Earth and Planetary Science Letters, Vol. 226, 1-2, pp. 41-52.Baltic Shield, Norway, Finland, RussiaGeophysics - seismics, xenoliths
DS200612-1064
2006
Pedersen, H.A.Pedersen, H.A., Bruneton, M., Maupin, V., SVEKALAPKO Seismic Tomography Working GroupLithospheric and sublithospheric anisotropy beneath the Baltic Shield from surface wave array analysis.Earth and Planetary Science Letters, Vol. 244, 3-4, Apr.30, pp. 590-05.Europe, Finland, Baltic ShieldGeophysics - seismics
DS200912-0577
2009
Pedersen, H.A.Pedersen, H.A., Fishwick, S., Snyder, D.B.A comparison of cratonic roots through consistent analysis of seismic surface waves.Lithos, Vol. 109, 1-2, pp. 81-95.MantleGeophysics - seismics
DS201805-0944
2018
Pedersen, H.A.Eeken, T., Goes, S., Pedersen, H.A., Arndt, N.T., Bouilhol, P.Seismic evidence for depth dependent metasomatism in cratons.Earth Planetary Science Letters, Vol. 491, pp. 148-159.Africa, Australia, Canada, Europegeothermometry

Abstract: The long-term stability of cratons has been attributed to low temperatures and depletion in iron and water, which decrease density and increase viscosity. However, steady-state thermal models based on heat flow and xenolith constraints systematically overpredict the seismic velocity-depth gradients in cratonic lithospheric mantle. Here we invert for the 1-D thermal structure and a depth distribution of metasomatic minerals that fit average Rayleigh-wave dispersion curves for the Archean Kaapvaal, Yilgarn and Slave cratons and the Proterozoic Baltic Shield below Finland. To match the seismic profiles, we need a significant amount of hydrous and/or carbonate minerals in the shallow lithospheric mantle, starting between the Moho and 70 km depth and extending down to at least 100-150 km. The metasomatic component can consist of 0.5-1 wt% water bound in amphibole, antigorite and chlorite, ?0.2 wt% water plus potassium to form phlogopite, or ?5 wt% CO2 plus Ca for carbonate, or a combination of these. Lithospheric temperatures that fit the seismic data are consistent with heat flow constraints, but most are lower than those inferred from xenolith geothermobarometry. The dispersion data require differences in Moho heat flux between individual cratons, and sublithospheric mantle temperatures that are 100-200?°C less beneath Yilgarn, Slave and Finland than beneath Kaapvaal. Significant upward-increasing metasomatism by water and CO2-rich fluids is not only a plausible mechanism to explain the average seismic structure of cratonic lithosphere but such metasomatism may also lead to the formation of mid-lithospheric discontinuities and would contribute to the positive chemical buoyancy of cratonic roots.
DS200612-1289
2006
Pedersen, L.B.Shomali, Z.H., Roberts, R.G., Pedersen, L.B., TORLithospheric structure of the Tornquist Zone resolved by nonlinear P and S teleseismic tomography along the TOR array.Tectonophysics, Vol. 416, 1-4, April 5, pp. 133-149.Europe, Baltic ShieldGeophysics - seismics
DS1996-1092
1996
Pedersen, L.E.Pedersen, L.E., Holm, P.M., Hoisteen, B.Plume related magmatism on the margin of the Baltic shields: geochemistry and isotopic signatures -dykesInternational Geological Congress 30th Session Beijing, Abstracts, Vol. 2, p. 356.GlobalGeochemistry, Proterozoic dyke swarm
DS200412-0432
2004
Pedersen, R.De Zeeuw van Dalfsen, E., Pedersen, R., Sigmundsson, F., Pagli, C.Satellite radar interferometry 1993-1999 suggest deep accumulation of magma near the crust mantle boundary at the Krafla volcaniGeophysical Research Letters, Vol.31, 13, July 16, 10.1029/2004 GL020059Europe, IcelandGeophysics - boundary
DS1987-0230
1987
Pedersen, R.B.Furnes, H., Pedersen, R.B., Maaloe, S.Petrology and geochemistry of spinel peridotite nodules and host basalt, VestspitsbergenNorsk Geologisk Tidsskrift, Vol. 66, pp. 53-68NorwayMineral Chemistry
DS1991-0009
1991
Pedersen, R.B.Albrektsen, B.A., Furnes, H., Pedersen, R.B.Formation of dunites in mantle tectonites, Leka ophiolite complex, SOURCE[ Journal of GeodynamicsJournal of Geodynamics, Vol. 13, No. 2-4, pp. 205-220NorwayOphiolite, Dunites
DS1991-0010
1991
Pedersen, R.B.Albrektsen, B.A., Furnes, H., Pedersen, R.B.Formation of dunites in mantle tectonites, Leka ophiolite complex NorwayJournal of Geodynamics, Vol. 13, No. 2-4, pp. 205-220NorwayTectonics, Mantle -dunites
DS1991-1321
1991
Pedersen, R.B.Pedersen, R.B., Furnes, H.Geology, magmatic affinity and geotectonic environment of some Caledonian ophiolites in NorwayJournal of Geodynamics, Vol. 13, No. 2-4, pp. 183-203NorwayOphiolites, Tectonics
DS201112-0390
2011
Pedersen, R.B.Grosch, E.G., Kosler, J., McLoughlin, N., Drost, K., Slama, J., Pedersen, R.B.Paleoarchean detrital zircon ages from the earliest tectonic basin in the Barberton greenstone belt, Kaapvaal craton, South Africa.Precambrian Research, Vol. 191, 1-2, pp. 85-99.Africa, South AfricaGeochronology
DS200812-0874
2008
Pedersen, S.Pedersen, S., Andersen, T., Konnerup-Madsen, J., Griffin, W.L.Recurrent mesoproterozoic continental magmatism in south central Norway.International Journal of Earth Sciences, In press availableEurope, NorwayMagmatism
DS2002-1237
2002
Pedersen, S. CraigPedersen, S. Craig, Upton, TapaniRamo, Jepsen, KalsbeekPaleoproterozoic (1740 Ma) rift related volcanism in the Hekla Sund region, field occurrence, geochemistryPrecambrian Research, Vol. 114, No. 3-4, Mar.15, pp.327-46.Greenland, eastern northTectonics
DS1992-1179
1992
Pedersen, T.Pedersen, T., Ro, H.E.Finite duration extension and decompression meltingEarth and Planetary Science Letters, Vol. 113, No. 1-2, September pp. 15-22MantleModel, Melt
DS1993-1213
1993
Pedersen, T.Pedersen, T.Heat flow in rift basins above a hot asthenosphereTerra Nova, Vol. 5, No. 2, pp. 144-149GlobalBasins, Heat flow
DS1982-0360
1982
Pederson, A.K.Larsen, L.M., Pederson, A.K.A Minor Carbonatite Occurrence in Southern West Greenland, ThetupertalikintrusionGeological Survey Greenland Report of activities, Vol. 110, pp. 38-43GreenlandCarbonatite, Qaqarssuk Complex
DS200912-0647
2009
Pederson, J.Roy, M., Jordan, T.H., Pederson, J.Colorado Plateau magmatism and uplift by warming of heterogeneous lithosphere.Nature, Vol. 459, June pp. 978-985.United States, Colorado PlateauMagmatism
DS1990-1169
1990
Pederson, J.C.Pederson, J.C., Lecouteur, P.C.The Thor Lake beryillium-rare metal deposits, Northwest Territories8th. IAGOD Symposium Guidebook, Held August 12-18th. Ottawa, Padgham, W.A., No. 13Northwest TerritoriesThor Lake, rare earth elements (REE).
DS2002-1238
2002
Pederson, J.L.Pederson, J.L., Mackley, R.D., Eddleman, J.L.Colorado Plateau uplift and erosion evaluated using GISGsa Today, Vol. 12, No. 8, August pp. 4-10.Colorado, Arizona, Utah, New MexicoStratigraphic - geomorphology, epeirogeny
DS1990-1170
1990
Pederson, L.B.Pederson, L.B., Rasmussen, T.M., Dyrelius, D.Construction of component maps from aeromagnetic total field anomaly mapsGeophysical Prospecting, Vol. 38, pp. 795-804GlobalGeophysics, Aeromagnetics- component maps
DS1995-0647
1995
Pederson, L.B.Gohl. K., Pederson, L.B.Collisional tectonics of the Baltic Shield in northern Gulf of Bothnia from seismic dat a BABEL projectGeophys. Journal of International, Vol. 120, No. 1, Jan. pp. 209-226.Finland, Sweden, Baltic ShieldTectonics, Geophysics -seismics
DS1992-0034
1992
Pederson, R.Annan, P., Liemieux, J., Pederson, R.Geotem as applied to the search for kimberlitesNorthwest Territories Geoscience Forum held November 25, 26th. 1992, Poster, AbstractNorthwest TerritoriesGeophysics - GeoteM.
DS1996-1334
1996
Pederson, R.N.Smith, R.S., Annan, A.P., Lemieux, J., Pederson, R.N.Application of a modified GEOTEM (R) system to reconnaissance exploration for kimberlites Point LakeGeophysics, Vol. 61, No. 1, Jan-Feb. pp. 82-92.Northwest TerritoriesGeophysics -GEOTEM., Kimberlites -Point Lake
DS1982-0227
1982
Pedler, A.D.Gregory, G.P., Mason, M.G., Pedler, A.D., Williams, S.D.Argyle Diamond Deposit Western AustraliaConfidential Report In-house., JULY 6TH. 5P.Australia, Western AustraliaGeology, Petrology, Mineralogy
DS1996-0141
1996
Pedler, P.J.Bloom, L.M., Pedler, P.J., Wragg, G.E.Implementation of enhanced areal interpretation using MapinfoComputers and Geosciences, Vol. 22, No. 5, pp. 459-466GlobalComputer, Program -Mapinfo remote sensing
DS201707-1346
2017
Pedrazzi, G.Lepore, G.O., Bindi, L., Pedrazzi, G., Conticelli, S., Bonazzi, P.Structural and chemical variations in phlogopite from lamproitic rocks of the central Mediterranean region.Lithos, in press available, 69p.Europe, Italylamproite

Abstract: Micas from mafic ultrapotassic rocks with lamproitic affinity from several localities of the Central Mediterranean region were studied through single-crystal X-ray diffraction (SC-XRD), electron microprobe analysis (EMPA) and Secondary Ion Mass Spectrometry (SIMS); Mössbauer Spectroscopy (MöS), when feasible, was also applied to minimise the number of unknown variables and uncertainties. Lamproitic samples analysed cover the most important Central Mediterranean type localities, from Plan d'Albard (Western Alps) to Sisco (Corsica), Montecatini Val di Cecina and Orciatico (Tuscany, Italy) and Torre Alfina (Northern Latium, Italy). The studied crystals show distinctive chemical and structural features; all of them belong to the phlogopite-annite join and crystallise in the 1 M polytype, except for micas from Torre Alfina, where both 1 M and 2 M1 polytypes were found. Studied micas have variable but generally high F and Ti contents, with Mg/(Mg + Fe) ranging from ~ 0.5 to ~ 0.9; 2M1 crystals from Torre Alfina radically differ in chemical composition, showing high contents of Ti and Fe as well as of Al in both tetrahedra and octahedra, leading to distinctive structural distortions, especially in tetrahedral sites. SIMS data indicate that studied micas are generally dehydrogenated with OH contents ranging from ~ 0.2 apfu (atoms per formula unit) for Orciatico and Torre Alfina to ~ 1.4 for Plan d'Albard crystals; this feature is also testified by the length of the c parameter, which decreases with the loss of hydrogen and/or the increase of the F ? OH substitution. Chemical and structural data suggest that the entry of high charge octahedral cations is mainly balanced by an oxy mechanism and, to a lesser extent, by a M3 +,4 +-Tschermak substitution. Our data confirm that Ti preferentially partitions into the M2 site and that different Ti and F contents, as well as different K/Al values, are both dependant upon fH2O and the composition of magma rather than controlled by P and T crystallisation conditions. The obtained data help to discriminate among lamproite-like rocks formed within a complex geodynamic framework but still related to a destructive tectonic margin and evidence different trends for micas from the youngest Torre Alfina (Northern Latium) lamproites, referred to the Apennine orogeny and those of the older lamproites from Orciatico, Montecatini Val di Cecina (Tuscany), Western Alps, and Corsica, the latter referred to the Alpine orogeny. Phlogopite crystals from the older lamproites fall within the compositional and structural field of worldwide phlogopites from both within-plate and subduction-related settings. Phlogopite from the Plio-Pleistocene lamproite-like occurrence in Tuscany and Northern Latium, despite crystals with low Mg# of the Torre Alfina rock plot well within the general field of the other crystals in less evolved samples, follows a different evolution trend similar to that of shoshonites from Tuscany and Northern Latium. On this basis, we argue that the observed differences are inherited by slight differences in the magma compositions that are related with different genetic and evolution pathways.
DS1994-0409
1994
Pedreira, A.De Medeiros Delgado, I., Pedreira, A., Thormon, C.H.Geology and mineral resources of Brasil : a reviewInternational Geology Review, Vol. 36, No. 6, June pp. 503-554BrazilMineral resources, Review
DS201112-0258
2010
Pedreira, A.J.De Sa Carneiro Chaves, M.L., Pedreira, A.J., Benitez, L.A intrusao diamantifera Salvador -1 ( Barra do mendes, BA.)5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 79-80.South America, Brazil, BahiaOverview of area - analyses
DS1987-0572
1987
Pedrick, J.N.Pedrick, J.N., Windom, K.E.Metasomatic enrichment of the lower crust and upper mantle atDelegate, New South Wales AustraliaGeological Society of America, Vol. 19, No. 4, March p.238. (abstract)AustraliaMantle genesis, Metasomatism
DS1998-1143
1998
Pedrick, J.N.Pedrick, J.N., Karstrom, K.E., Bowring, S.A.Reconciliation of conflicting tectonic models for Proterozoic rocks of northern New MexicoJournal of Met. Geol, Vol. 16, No. 5, Sept. pp. 687-New MexicoTectonics
DS200612-0014
2006
Pedrosa Soares, A.C.Alkmim, F.F., Marshak, S., Pedrosa Soares, A.C., Peres, G.G., Cruz, S.C., Whittington, A.Kinematic evolution of the Aracuai West Congo in Brazil and Africa: nutcracker tectonics during the Neoproterozoic assembly of Gondwana.Precambrian Research, Vol. 149, 1-2, pp. 43-64.South America, BrazilTectonics - collisional, orogen
DS1992-1180
1992
Pedrosa-Soares, A.C.Pedrosa-Soares, A.C., Noce, C.M., Vidal, Ph., Montero, R.L.B.P.Toward a new tectonic model for the Late Proterozoic Aracuai southeast Brasil-west Congolian southwest Africa beltJournal of South American Earth Sciences, Vol. 6, No. 1-2, pp. 33-47Brazil, Southwest AfricaTectonics, Proterozoic
DS1998-1144
1998
Pedrosa-Soares, A.C.Pedrosa-Soares, A.C., Vidal, P., Leondaros, O. Brito-.Neoproterozoic oceanic remnants in eastern Brasil: further evidence and refutation of exclusively ensialicGeology, Vol. 26, No. 6, June pp. 519-522.BrazilAracuai West Congo orogen, Craton - Sa Francisco, Congo
DS2001-0901
2001
Pedrosa-Soares, A.C.Pedrosa-Soares, A.C., Noce, C.M., Wiedemann, PintoThe Aracuai West Congo Orogen in Brasil: an overview of a confined orogen formed during Gondwanaland assembly.Precambrian Research, Vol. 110, pp. 307-24.Brazil, RodiniaOrogeny, Tectonics
DS2002-0104
2002
Peece, C.Barnett, W., Peece, C.Expanding the geological model for Finsch mineSouth African Journal of Geology, Vol. 105, No. 4, pp. 381-400.South AfricaGeology, Deposit - Finsch
DS202109-1458
2021
Peeira, R.S.de Caravlho, L.D.V., Jalowitzki, T., Scholz, R., de Oliveira Gonzales, G., Rocha, M.P., Peeira, R.S., Lana, C., de Castro, P., Queiroga, G., Fuck, R.A.An exotic Cretaceous kimberlite linked to metasomatized lithospheric mantle beneath the southwestern margin of the Sao Francisco Craton, Brazil.Geoscience Frontiers, doi,org/101016/j.gsf.2021.101.28South America, Brazildeposit - Osvaldo Franca 1

Abstract: We present major and trace element compositions of mineral concentrates comprising garnet xenocrysts, ilmenite, phlogopite, spinel, zircon, and uncommon minerals (titanite, calzirtite, anatase, baddeleyite and pyrochlore) of a newly discovered Late Cretaceous kimberlite (U-Pb zircon age 90.0 ± 1.3 Ma; 2?) named Osvaldo França 1, located in the Alto Paranaíba Igneous Province (APIP), southeastern Brazil. Pyrope grains are lherzolitic (Lherz-1, Lherz-2 and Lherz-3), harzburgitic (Harz-3) and wehrlitic (Wehr-2). The pyrope xenocrysts cover a wide mantle column in the subcratonic lithosphere (66-143 km; 20-43 kbar) at relatively low temperatures (811-875 °C). The shallowest part of this mantle is represented by Lherz-1 pyropes (20-32 kbar), which have low-Cr (Cr2O3 = 1.74-6.89 wt.%) and fractionated middle to heavy rare earth elements (MREE-HREE) pattern. The deepest samples are represented by Lherz-2, Lherz-3, Harz-3, and Wehr-2 pyropes (36-43 kbar). They contain high-Cr contents (Cr2O3 = 7.36-11.19 wt.%) and are characterized by sinusoidal (Lherz-2 and Wehr-2) and spoon-like (Lherz-3 and Harz-3) REE patterns. According to their REE and trace elements, pyrope xenocrysts have enriched nature (e.g., Ce and Yb vs. Cr2O3), indicating that the cratonic lithosphere has been affected by a silicate melt with subalkaline/tholeiite composition due to their low Zr, Ti and Y concentrations. Besides minerals with typical kimberlitic signatures, such as ilmenite and zircon, the exotic compositions of phlogopite and ulvöspinel suggest an enriched component in the magma source. The formation of rare mineral phases with strong enrichment of light-REE (LREE) and high field strength elements (HFSE) is attributed to the late-stage kimberlitic melt. We propose a tectonic model where a thermal anomaly, represented by the low-velocity seismic anomaly observed in P-wave seismic tomography images, supplied heat to activate the alkaline magmatism from a metasomatized cratonic mantle source during the late-stages of Gondwana fragmentation and consequent South Atlantic Ocean opening. The metasomatism recorded by mineral phases is a product of long-lived recycling of subducted oceanic plates since the Neoproterozoic (Brasiliano Orogeny) or even older collisional events, contributing to the exotic character of the Osvaldo França 1 kimberlite, as well as to the cratonic lithospheric mantle.
DS201012-0652
2010
Peel, E.Sanchez Bellucci, L., Peel, E., Masquelin, H.Neoproterozoic tectonic synthesis of Uruguay.International Geology Review, Vol. 52, 1, pp. 51-78.South America, UruguayTectonics
DS201012-0653
2010
Peel, E.Sanchez Bellucci, L., Peel, E., Oyhantcabal, P.Precambrian geotectonic units of the Rio de la Plat a craton.International Geology Review, Vol. 52, 1, pp. 32-50.South AmericaTectonics
DS201012-0654
2010
Peel, E.Sanchez Bettucci, L., Peel, E., Masquelin, H.Neoproterozoic tectonic synthesis of Uruguay.International Geology Review, Vol. 52, 1, pp. 51-78.South America, UruguayTectonics
DS201012-0655
2010
Peel, E.Sanchez Bettucci, L., Peel, E., Oyhantcabal, P.Precambrian geotectonic units of the Rio de la Plat a craton.International Geology Review, Vol. 52, 1, pp. 32-50.South America, BrazilTectonics
DS201112-0065
2011
Peel, E.Basei, M.A.S., Peel, E., Sanchez Bettuci, L., Preciozzi, F., Nutman, A.P.The basement of the Punta del Este Terrane (Uruguay): an African Mesoproterozoic fragment at the eastern border of the South American Rio de la Plat a craton.International Journal of Earth Sciences, Vol. 100, 2, pp. 289-304.South America, UruguayCraton, Rodinia
DS201903-0499
2019
Peel, E.Bologna, M.S., Dragone, G.N., Muzio, R., Peel, E., Nunez, Demarco, P., Ussami, N.Electrical structure of the lithosphere from Rio de la Plata craton to Parana Basin: amalgamation of cratonic and refertilized lithospheres in SW Gondwanaland.Tectonics, Vol. 38, 1, pp. 77-94.South America, Brazilcraton

Abstract: We conducted a magnetotelluric (MT) study from Paleoproterozoic Rio de la Plata Craton, in Uruguay, toward Paleozoic?Mesozoic Paraná Basin, in Brazil. The 850?km?long MT transect comprises 35 evenly spaced broadband electromagnetic soundings sites. In the Paraná Basin, 11 additional long?period measurements were acquired to extend the maximum depth of investigation. All data were inverted using two? and three?dimensional approaches obtaining the electrical resistivity structure from the surface down to 200 km. The Rio de la Plata Craton is >200?km thick and resistive (~2,000 ?m). Its northern limit is electrically defined by a lithosphere scale lateral transition and lower crust conductive anomalies (1-10 ?m) interpreted as a Paleoproterozoic suture at the southern edge of Rivera?Taquarembó Block. The latter is characterized by an approximately 100?km thick and moderate resistive (>500 ?m) upper mantle. The Ibaré shear zone is another suture where an ocean?ocean subduction generated the 120?km thick and resistive (>1,000 ?m) São Gabriel juvenile arc. Proceeding northward, a 70? to 80?km thick, 150?km wide, and inclined resistive zone is imaged. This zone could be remnant of an oceanic lithosphere or island arcs accreted at the southern border of Paraná Basin. The MT transect terminates within the southern Paraná Basin where a 150? to 200?km?thick less resistive lithosphere (<1,000 ?m) may indicate refertilization processes during plate subduction and ocean closure in Neoproterozoic?Cambrian time. Our MT data support a tectonic model of NNE-SSW convergence for this segment of SW Gondwanaland.
DS202004-0507
2020
Peel, E.Demarco, P.N., Masquelin, H., Prezzi, C., Muzio, R., Loureiro, J., Peel, E., Campal, N., Sanchez Bettucci, L. Aeromagnetic patterns in southern Uruguay: Precambrian- Mesozoic dyke swarms and Mesozoic rifting structural and tectonic evolution.Tectonophysics, in press available 40p. PdfSouth America, Uruguaygeophysics

Abstract: New high-resolution airborne magnetic data of Uruguay allowed constructing new maps concerning the spatial distribution of dyke swarms, main faults and other magnetic bodies, which compose the Uruguayan Shield. We combined geophysical analyses (vertical derivatives, upward continuation, Euler deconvolution), structural analyses of the magnetic maps and previous geological data in order to discriminate the main structural features of the Uruguayan Shield and contribute to a better understanding of its tectonic evolution. The magnetic maps revealed several outstanding features in the Uruguayan Shield. The Paleoproterozoic dyke swarm is larger, denser, more widespread and complex than originally thought, suggesting a possible plume origin. In addition, a new Mesozoic dyke swarm, as complex as the previous one, was identified crosscutting the Paleoproterozoic dyke swarm and the Neoproterozoic orogenic structures. Moreover, this swarm is connected to volcanic calderas in the Merín basin, and shows displacements along Neoproterozoic shear zones, in the magnetic maps, revealing its brittle reactivation during Mesozoic times. The new observations clarify how Proterozoic basement structures controlled the development of the Mesozoic rift. Paleoproterozoic dyke swarms were reactivated as normal faults and Neoproterozoic structures hindered the rift growth, deflecting the deformation in transcurrent movements. Meanwhile, the Mesozoic dyke swarm was developed in a perpendicular direction to the Neoproterozoic structures. Moreover, these findings contradict the current rift model for Uruguay and rise a new model in which the Mesozoic rift developed as two rift basins connected by a central transfer zone, generated by the reactivation of Dom Feliciano Belt structures, between the Sierra Ballena and Sarandí del Yí Shear Zones.
DS1991-1322
1991
Peel, J.S.Peel, J.S., Sonderholm, M.Sedimentary basins: evolution, facies and sediment budgetGronslands Geologiske Undersogelse, 160pGreenlandSedimentary basins, Table of contents
DS2003-1054
2003
Peeling, G.Peeling, G.Diamond certification in CanadaCanada Forum: Held Nov. 204, Joint Ventures-Joint Rewards. The resource, [email protected] 180p. binder $ 120.00CanadaConference - talk
DS200412-1514
2003
Peeling, G.Peeling, G.Diamond certification in Canada.Canada Forum: Held Nov. 204, Joint Ventures-Joint Rewards. The resource industry and aboriginal development co, [email protected] 180p. binder $ 120.00CanadaConference - talk
DS1989-1189
1989
Peeling, G.R.Peeling, G.R.The Canada U.S. free trade agreement and its effect on Canada's Pacific Rim mineral tradePreprint - presentation at AAAS Annual Meeting, on Mineral Resources and, 13p. Database # 18057Canada, United StatesEconomics, Trade
DS1991-1323
1991
Peeling, G.R.Peeling, G.R.Australia's eclogically sustainable development working group on miningWorld Mineral Notes, Vol. 7, No. 5, October pp. 1-2AustraliaLegal, Environmental, Mining
DS1983-0349
1983
Peeples, W.J.Keller, G.R., Coultrip, R.L., Peeples, W.J., Aiken, C.L.V.A Regional Gravity Study of the Colorado Plateau and Adjacent Regions.Geological Society of America (GSA), Vol. 15, No. 5, P. 317. (abstract.).Colorado, Rocky Mountains, Colorado Plateau, Arizona, New MexicoMid-continent
DS1984-0398
1984
Peeples, W.J.Keller, G.R., Kruger, J.M., Peeples, W.J.The Regional Geophysical and Tectonic Setting of the Ouachita SystemGeological Society of America (GSA), Vol. 16, No. 2, FEBRUARY P. 88. (abstract.).GlobalMid-continent
DS1993-1214
1993
Pegg, C.Pegg, C.The ABC diamond district - Kirkland Lake. Regional settingHaileybury Sch. Mines, Canadian Society of Exploration Geophysists, 70p.Ontario, Kirkland LakeGeophysics
DS1990-1171
1990
Pegg, C.C.Pegg, C.C., Brummer, J.J., MacDadyen, D.A.Discovery of kimberlite diatremes in the Kirkland Lake area, Ontario #1The Canadian Institute of Mining, Metallurgy and Petroleum (CIM), The Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Vol.89, No. 935, April p. 90. AbstractOntarioDiatremes -five, Diamondiferous tests
DS1991-1324
1991
Pegg, C.C.Pegg, C.C., Brummer, J.J., MacFayden, D.A.Discovery of kimberlite diatremes in the Kirkland Lake area, Ontario #2The Canadian Mining and Metallurgical Bulletin (CIM Bulletin) ., Session, Vol. 84, No. 947, March p. 99. AbstractOntarioKimberlite -diatremes, Kirkland Lake area
DS1992-0178
1992
Pegg, C.C.Brummer, J.J., MacFadyen, D.A., Pegg, C.C.Discovery of kimberlites in the Kirkland Lake area, northern Ontario, Canada. Part I: kimberlite discoveries, sampling, diamondcontent, age, emplacementThe Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Exploration Mining Geology, Vol. 1, No. 4, October pp. 351-370OntarioGeology, geophysics -aeromagnetics, Kimberlite pipes
DS1992-0179
1992
Pegg, C.C.Brummer, J.J., MacFadyen, D.A., Pegg, C.C.Discovery of kimberlites in the Kirkland Lake area, northern Ontario, Canada. Part I: early surveys and surficial geologyThe Canadian Institute of Mining, Metallurgy and Petroleum (CIM), Vol. 1, No. 4, October pp. 339-350OntarioHistory, Quaternary, sampling programs
DS1998-1145
1998
Pegler, E.A.Pegler, E.A., McMillan, I.K.Tectonostratigraphical evolution of the Orange Basin, southwestern AfricaJournal of African Earth Sciences, Vol. 27, 1A, p. 147. AbstractSouth AfricaTectonics
DS1999-0547
1999
Pegler, E.A.Pegler, E.A.Mid to late Quaternary environments and stratigraphy of the southern Sierra Leone shelf, West Africa.Journal of Geological Society India, Vol. 156, No. 5, Sept. pp. 977-90.GlobalGeomorphology
DS200712-0825
2007
Pehkonen-Ollila, A.R.Pehkonen-Ollila, A.R., Gehor, S.Mineral chemistry of pyrochlore in residually inherited Fe P Nb laterite ore bodies at Sokli carbonatite complex.Plates, Plumes, and Paradigms, 1p. abstract p. A771.Europe, FinlandSokli
DS200412-2098
2004
Pehl, J.Wenk, H.R., Lonardeli, I., Pehl, J., Devine, J., Prakapenka, V., Shen, G., Mao, H-K.In situ observation of texture development in olivine, ringwoodite, magnesiowustite and silicate perovskite at high pressure.Earth and Planetary Science Letters, Vol. 226, 3-4, Oct. 15, pp.507-519.Mantle, United States, New MexicoMagnesium silicates, San Carlos
DS200612-1419
2005
PehrssonTella, S., Paul, D., Davis, W.J., Berman, R.G., Sandeman, H.A., Peterson, T.D., Pehrsson, KerswillBedrock geology compilation and regional synthesis, parts of Hearne domain, Nunavut.Geological Survey of Canada Open file, No. 4729, 2 sheetsCanada, NunavutMap - geology - mentions diamonds
DS1996-1093
1996
Pehrsson, S.Pehrsson, S., Hanmer, S., Van Breemen, O.uranium-lead (U-Pb) geochronology of the Raglan gabbro belt: implications for an ensialic marginal basin GrenvilleCanadian Journal of Earth Sciences, Vol. 33, pp. 691-702.Quebec, Labrador, UngavaGeochronology, Orogeny - Grenville
DS2001-0902
2001
Pehrsson, S.Pehrsson, S., Berman, R.The Rae Hearne boundary zone in the Baker Lake area: where are the breaks?29th. Yellowknife Geoscience Forum, Nov. 21-23, abstract p. 65-6.Northwest Territories, Saskatchewan, AlbertaTectonics
DS200512-0193
2005
Pehrsson, S.Corrigan, D., St.Onge, M., Pehrsson, S.Paleproterozoic growth of continental lithosphere: a perspective from Laurentia in Canada.GAC Annual Meeting Halifax May 15-19, Abstract 1p.Canada, NunavutCraton, tectonics
DS200512-0402
2005
Pehrsson, S.Harper, C.T., Van Breeman, O., Wodick,N., Pehrsson, S., Heaman, L., Hartlaub, R.The Paleoproterozoic lithostructural history and thermotectonic reactivation of the Archean basement in southern Hearne domain of northeastern Saskatchewan.GAC Annual Meeting Halifax May 15-19, Abstract 1p.Canada, SaskatchewanTrans Hudson orogen
DS200712-0072
2007
Pehrsson, S.Berman, R.G., Davis, W.J., Pehrsson, S.Collisional snowbird tectonic zone resurrected: growth of Laurentia during accretionary phase of the Hudsonian orogeny.Geology, Vol. 35, 10, Oct. pp. 911-914.Canada, Manitoba, Saskatchewan, Northwest TerritoriesTectonics - Laurentia
DS202004-0522
2020
Pehrsson, S.Kellett, D.A., Pehrsson, S., Skipton, D., Regis, D., Camacho, A., Schneider, D., Berman, R.Thermochronological history of the Northern Canadian Shield. Nuna, Churchill Province, Trans-Hudson orogen, Thelon, RaePrecambrian Research, doi.org/10.1016/j.precamres.2020.105703 in press available 80p. PdfCanadageothermometry

Abstract: The northern Canadian Shield is comprised of multiple Archean cratons that were sutured by the late Paleoproterozoic to form the Canadian component of supercontinent Nuna. More than 2000 combined K-Ar and 40Ar/39Ar cooling ages from across the region reveal a stark contrast in upper and lower plate thermal responses to Nuna-forming events, with the Churchill Province in particular revealing near complete thermal reworking during the late Paleoproterozoic. We review the detailed cooling history for five regions that span the Churchill Province and Trans-Hudson orogen (THO): Thelon Tectonic Zone, South Rae, Reindeer Zone, South Hall Peninsula, and the Cape Smith Belt. The cooling patterns across Churchill Province are revealed in two >1500 km transects. At the plate scale, Churchill’s cooling history is dominated by THO accretionary and collisional events, during which it formed the upper plate. Cooling ages generally young from west to east across both southern and central Churchill, and latest cooling in the THO is 50 myr older in southernmost Churchill (Reindeer Zone) compared to eastern Churchill (Hall Peninsula), indicating diachronous thermal equilibration across 2000 km strike length of the THO. Churchill exhibits relatively high post-terminal THO cooling rates of ~4 °C/myr, which support other geological evidence for widespread rapid exhumation of the THO upper plate following terminal collision, potentially in response to lithospheric delamination.
DS202103-0402
2021
Pehrsson, S.Regis, D., Pehrsson, S., Martel, E., Thiessen, E., Peterson, T., Kellett, D.Post - 1.9 Ga evolution of the south Rae craton ( Northwest Territories), Canada: a paleoproterozoic orogenic collapse system.Precambrian Research, Vol. 355, 106105, 29p. PdfCanada, Northwest Territoriessunduction

Abstract: The Trans-Hudson Orogen (THO), formed from the convergence between the Superior craton and the composite Churchill Upper Plate (CUP), is one of the best-preserved examples of a collisional orogen in the Paleoproterozoic. Similar to modern collision systems such as the Himalayan orogen, it is characterized by a composite upper plate in which terrane accretion established a continental plateau that was tectonically and magmatically active for >100 myr. Our study presents new petrological and geochronological data for four samples collected in three lithotectonic domains of the south Rae craton (one of the CUP terranes). The results presented here allow us to re-define the previously proposed extent of THO reworking in the CUP and afford the opportunity to study and compare the evolution of various fragments that illustrate differing levels of a collapsed plateau in the CUP hinterland. The new data indicate that the south Rae craton locally preserves evidence for burial at 1.855-1.84 Ga with peak metamorphic conditions at approximately 790 °C and 9.5-12.5 kbar followed by rapid cooling and decompression melting (P < 6 kbar) at ca. 1.835-1.826 Ga. These results, which provide important and so far missing Pressure-Temperature-time (P-T-t) constraints on the evolution of the south Rae craton in the Northwest Territories at Trans-Hudson time, coupled with existing regional geochronological and geochemical data, are used to propose an updated model for the post-1.9 Ga THO collision and extensional collapse. Our results reveal that: i) initial thickening in the upper plate started at Snowbird time (ca. 1.94 Ga), then continued via Sask collision (with high-grade metamorphism recorded in the south Rae craton, ca. 1.85 Ga), and ended with Superior collision (ca. 1.83 Ga); ii) the extent of the THO structural and metamorphic overprint in the SW CUP is much broader across strike than previously recognized, and iii) T-t data in the south Rae are indicative of relatively fast cooling rates (8-25 °C/Ma) compared to other known Precambrian orogens. We suggest that the Paleoproterozoic THO represents the first record of a major ‘modern-style’ orogenic plateau collapse in Earth’s history.
DS1999-0150
1999
Pehrsson, S.J.Corrigan, D., Pehrsson, S.J., MacHattie, Piper, WrightLithotectonic framework of the Trans Hudson Orogen in the northwestern Reindeer Zone: update recent mapping.Geological Survey of Canada (GSC), Current Research 1999- C, pp. 169-78.SaskatchewanTectonics, Trans Hudson Orogen
DS2000-0751
2000
Pehrsson, S.J.Pehrsson, S.J., Chacko, T., Pilkington, M., VilleneuveAnton terrane revisited: Late Archean exhumation of a moderate pressure granulite terrane in western SlaveGeology, Vol. 28, No. 12, Dec. pp. 1075-78.Northwest TerritoriesAnton terrane, Tectonic denudation
DS2002-0143
2002
Pehrsson, S.J.Berman, R., Pehrsson, S.J., Davis, W.J., Snyder, TellaA new model for ca 1.9 Ga tectonometamorphism in the western Churchill province: linked upper crustal thickGac/mac Annual Meeting, Saskatoon, Abstract Volume, P.9., p.9.SaskatchewanTectonic reconstructions
DS2002-0144
2002
Pehrsson, S.J.Berman, R., Pehrsson, S.J., Davis, W.J., Snyder, TellaA new model for ca 1.9 Ga tectonometamorphism in the western Churchill province: linked upper crustal thickGac/mac Annual Meeting, Saskatoon, Abstract Volume, P.9., p.9.SaskatchewanTectonic reconstructions
DS2003-1055
2003
Pehrsson, S.J.Pehrsson, S.J., Peterson, T., Davis, W.J., Sandeman, Skulski, Van BreenenAncient Archean crust in the Western Churchill Province: a review of direct and indirect31st Yellowknife Geoscience Forum, p. 75. (abst.)Saskatchewan, Manitoba, NunavutTectonics - lithosphere
DS2003-1056
2003
Pehrsson, S.J.Pehrsson, S.J., Peterson, T., Davis, W.J., Sandeman, Skulski, Van BreenenThe Western Churchill metallogeny project: from Melville to Uranium City, a new look31st Yellowknife Geoscience Forum, p. 77. (abst.)Saskatchewan, Manitoba, Nunavut, Northwest TerritoriesBedrock compilation
DS200412-1515
2003
Pehrsson, S.J.Pehrsson, S.J., Peterson, T., Davis, W.J., Sandeman, Skulski, Van Breenen, Hartlaub, Wodicks, Hanmer, CousensAncient Archean crust in the Western Churchill Province: a review of direct and indirect evidence.31st Yellowknife Geoscience Forum, p. 75. (abst.)Canada, Saskatchewan, Manitoba, NunavutTectonics - lithosphere
DS200412-1516
2003
Pehrsson, S.J.Pehrsson, S.J., Peterson, T., Davis, W.J., Sandeman, Skulski, Van Breenen, Hartlaub, Wodicks, Hanmer, CousensThe Western Churchill metallogeny project: from Melville to Uranium City, a new look at the largest under explored Craton in the31st Yellowknife Geoscience Forum, p. 77. (abst.)Canada, Saskatchewan, Manitoba, Northwest Territories, NunavutBedrock compilation
DS200612-0352
2006
Pehrsson, S.J.Dredge, L.A., Pehrsson, S.J.Geochemistry and physical properties of till in northern most Manitoba.Geological Survey of Canada, Open file 5320, 134p. $ 9.10Canada, ManitobaGeochemistry - till not specific to diamonds
DS201312-0694
2013
Pehrsson, S.J.Pehrsson, S.J., Berman, R.G., Eglinton, B., Rainbird, R.Two Neoarchean supercontinents revisited: the case for a Rae family of cratons.Precambrian Research, Vol. 232, pp. 27-43.Canada, SaskatchewanKenoraland revised, Nunavutia
DS201412-0352
2012
Pehrsson, S.J.Helmstaedt, H., Pehrsson, S.J.Geology and tectonic evolution of the Slave Province, Canada: a post lithoprobe perspective.Tectonics, Geological Survey of Canada, Special Paper, 49, pp. 381-468.Canada, Northwest TerritoriesTectonics - lithoprobe
DS201606-1104
2016
Pehrsson, S.J.Pehrsson, S.J., Eglinton, B.M., Evans, D.A.A., Huston, D.Metallogeny and its link to orogenic style during the Nuna supercontinent.Geological Society of London Special Publication Supercontinent Cycles through Earth History., Vol. 424, pp. 83-94.United States, CanadaSupercontinents

Abstract: The link between observed episodicity in ore deposit formation and preservation and the supercontinent cycle is well established, but this general framework has not, however, been able to explain a lack of deposits associated with some accretionary orogens during specific periods of Earth history. Here we show that there are intriguing correlations between styles of orogenesis and specific mineral deposit types, in the context of the Nuna supercontinent cycle. Using animated global reconstructions of Nuna's assembly and initial breakup, and integrating extensive databases of mineral deposits, stratigraphy, geochronology and palaeomagnetism we are able to assess spatial patterns of deposit formation and preservation. We find that lode gold, volcanic-hosted-massive-sulphide and nickel-copper deposits peak during closure of Nuna's interior ocean but decline during subsequent peripheral orogenesis, suggesting that accretionary style is also important. Deposits such as intrusion-related gold, carbonate-hosted lead-zinc and unconformity uranium deposits are associated with the post-assembly, peripheral orogenic phase. These observations imply that the use of plate reconstructions to assess orogenic style, although challenging for the Precambrian, can be a powerful tool for mineral exploration targeting.
DS202103-0396
2021
Pehrsson, S.J.Neil, B.J.C., Gibson, H.D., Pehrsson, S.J., Martel, E., Thiessen, E.J., Crowley, J.L.Provenance, stratigraphic and precise depositional age constraints for an outlier of the 1.9 to 1.8 Ga Nonacho Group, Rae craton, Northwest Territories, Canada.Precambrian Research, Vol. 352, 105999, 15p. PdfCanada, Northwest Territoriesgeochronology

Abstract: The Nonacho Group comprises six formations of continental clastic rocks that were deposited between 1.91 and 1.83?Ga. The Nonacho Group is part of a broader assemblage of conglomerate and sandstone that was deposited atop the Rae craton in response to the amalgamation of Laurentia and supercontinent Nuna, but the details of its tectonic setting are contentious. This paper documents an outlier of Nonacho Group rocks ?50?km east of the main Nonacho basin. Field observations and LA-ICPMS (laser ablation inductively coupled plasma mass spectrometry) U-Pb detrital zircon geochronology are integrated with previous studies of the main basin to better understand the group’s depositional history, provenance and tectonic setting. The lithology and detrital zircon age spectra of the outlier allow for its correlation to the upper two formations of the Nonacho Group. CA-ID-TIMS (chemical abrasion isotope dilution thermal ionization mass spectrometry) analyses of two fragments of the youngest detrital zircon provide a maximum depositional age of 1901.0?±?0.9?Ma. A felsic volcanic cobble dated at ca. 2.38?Ga provides evidence of volcanism during the Arrowsmith orogeny. Detrital zircon dates recovered from the outlier (ca. 3.4-3.0, 2.7, 2.5-2.3 and 2.0-1.9?Ga) are consistent with derivation from topography of the Taltson and/or Thelon orogens on the western margin of the Rae craton. Taltson-Thelon (2.0 to 1.9?Ga) aged detritus is only abundant in the upper two formations of the Nonacho Group, marking a change in provenance from the lower formations. This change in provenance may have coincided with a period of renewed uplift and the unroofing of Taltson-Thelon plutons. The detrital zircon provenance and depositional age of the Nonacho Group is consistent with models that link its deposition to the Taltson and/or Thelon orogens. However, tectonism associated with the 1.9 to 1.8?Ga Snowbird and Trans-Hudson orogens to the east could also have affected basin formation or the change in provenance from the lower to upper Nonacho Group. This study highlights the importance of CA-ID-TIMS in establishing accurate and precise maximum depositional ages for sedimentary successions.
DS202109-1470
2021
Pehrsson, S.J.Helmstaedt, H., Pehrsson, S.J., Stubley, M.P.The Slave Province, Canada - geological evolution of an archean diamondiferous craton.Geological Association of Canada Bookstore, https://gac.ca/publications/bookstore Special Paper 51, 216p. Prices 42.50 member, $75.00 non-member isbn:978-1-897095-89-8Canada, Northwest TerritoriesCraton

Abstract: With its well-exposed geologic record from the Hadean Acasta gneiss complex through to Phanerozoic kimberlites, the Slave craton of northwestern Canada has long been a focus for research into early Earth evolution of both the crust and lithosphere. As a result, it has become one of the most extensively studied Archean cratons in the world. This multidisciplinary volume provides an authoritative overview of the Slave craton literally from the bottom up, integrating the nature of its lithosphere based on kimberlitic mantle samples with its upper crustal geology to provide a new model for its Archean assembly and cratonization. All aspects of Slave craton geology are covered, from the stratigraphy of its famous gold camps to the history of exploration and nature of its world-class diamondiferous kimberlite fields. Detailed and well-illustrated chapters cover its terranes and greenstone belts, magmatism, geophysical character, tectono-metamorphic evolution, and Paleoproterozoic marginal sequences. The book’s wealth of data and up-to-date bibliography provide a unique resource for understanding, researching and teaching Archean geology and subcrustal and cratonic evolution. It elegantly integrates diverse fields to provide one of the most comprehensive models for the craton and the protracted, multiphase formation of its diamond-bearing lithospheric root. (JK Note: the link above takes you to the GAC web site where Special Paper 51 can be purchased. Because the GAC only provides the abstract and a photo of the front page, I am providing a Table of Contents pdf.)
DS200512-0834
2005
Pehrsson, S.L.Pehrsson, S.L., Berman, R.G., Rainbird, R., Davis, W., Skulski, Sanborn-Barrie, Van Breeman, Corrigan, TellaInterior collisional orogenesis related to supercontinent assembly: the ca. 1.9- 1.5 Ga tectonic history of the western Churchill province.GAC Annual Meeting Halifax May 15-19, Abstract 1p.Canada, SaskatchewanNuna, tectonics
DS201012-0125
2009
Pehsson, S.Corrigan, D., Pehsson, S., Wodicka, N., De Kemp, E.The Paleoproterozoic Trans Hudson Orogen: a prototype of modern accretionary processes.Ancient Orogens and Modern Analogues, Geological Society of London Special Publication, No. 327, pp. 457-479.CanadaCraton
DS200812-1282
2008
Pei, F.P.Xu, W-L., Yang, D.B., Gao, S., Yu, Y., Pei, F.P.Mesozoic lithospheric mantle of the Central North Chin a craton: evidence from peridotite xenoliths.Goldschmidt Conference 2008, Abstract p.A1047.ChinaXenoliths
DS201112-1129
2011
Pei, F.P.Xu,L., Zhou, Q.J., Pei, F.P., Yang, D.B., Gao, S., Wang, W., Feng, H.Recycling lower continental crust in an intra continental setting: mineral chemistry and oxygen isotope insights from websterite xenoliths.Goldschmidt Conference 2011, abstract p.2197.ChinaNorth China craton
DS201212-0797
2013
Pei, F-P.Xu, W-L., Zhou, Q-J., Pei, F-P., Gao, S., Li, Q-L., Yang, Y-H.Destructive of the North Chin a craton: delamin ation or thermal/chemical erosion? Mineral chemistry and oxygen isotope insights from websterite xenoliths.Gondwana Research, Vol. 23, 1, pp. 119-129.ChinaCraton, destruction
DS201212-0227
2012
Pei, J.Gao, C., McAndrews, J.H., Wang, X., Menzies, J., Turton, C.L., Wood, B.D., Pei, J., Kodors, C.Glaciation of North America in the James Bay Lowland, Canada, 3-5 Ma.Geology, Vol. 40, 11, pp. 975-978.Canada, Ontario, James Bay LowlandsGeomorphology
DS200812-1144
2008
Pei, S.Sun, Y., Toksoz, M.N., Pei, S., Zhao, D., Morgan, F.D., Rosca, A.S wave tomography of the crust and uppermost mantle in China.Journal of geophysical Research, Vol. 113, B11307.ChinaGeophysics - seismics
DS200412-2169
2003
Pei, X.Yang, J., Xu, Z., Dobrzhinetskaya, L.F., Green, H.W., Pei, X., Shi, R., Wu, C., Wooden, J.L., Zhang, J., WanDiscovery of metamorphic diamonds in central China: an indication of a > 4000 km long zone of deep subduction resulting from mulTerra Nova, Vol. 15, pp. 370-379.ChinaSubduction, Central Orogenic Belt, UHP
DS200812-0875
2008
Pein, H.Pein, H.Alluvial diamond exploration in tropical Africa.GSSA-SEG Meeting Held July, Johannesburg, 73 Power point slidesAfrica, West AfricaAlluvials, Pangea
DS200912-0168
2009
Peinado, M.Dessai, A.G., Peinado, M., Gokam, S.G., Downes, H.Structure of the deep crust beneath the Central Indian Tectonic Zone: an integration of geophysical and xenolith data.Gondwana Research, Vol. 17, 1., pp. 162-170.IndiaTectonics
DS201012-0152
2010
Peinado, M.Dessai, A.G., Peinado, M., Gokarn, S.G., Downes, H.Structure of the deep crust beneath the Central Indian Tectonic Zone: an integration of geophysical dat a and xenolith dat a.Gondwana Research, Vol. 17, pp. 162-170.IndiaGeothermometry
DS200712-0898
2006
Peirce, C.Rodger, M., Watts, A.B., Greenroyd, C.J., Peirce, C., Hobbs, R.W.Evidence for unusually thin oceanic crust and strong mantle beneath the Amazon Fan.Geology, Vol. 34, 12, pp. 1081-1084.South AmericaGeophysics - seismics
DS1998-1146
1998
Peirce, J.W.Peirce, J.W., Goussev, Charters, Abercrombie, De PaoliIntrasedimentary magnetization by vertical fluid flow and exotic geochemistry.Leading Edge, Vol. 17, No. 1, pp. 89-92.Alberta, Western CanadaGeophysics - magnetics, Basin
DS202203-0362
2022
Peireira, R.S.Peireira, R.S., de Carvallo, L.D.V., Fuck, R.A.Primary source of alluvial diamonds from the Santo Antonio do Bonito, Santo Inacio and Douradinho rivers, Coromandel region, Minas Gerais, Brazil.Journal of South American Earth Sciences, Vol. 111, 15p. PdfSouth America, Brazil, Minas Geraisdeposit - Coromandel

Abstract: In the midwestern Minas Gerais, Brazil, kimberlite intrusions, particularly kamafugite and alkaline complexes, occur along the NW-SE-oriented Alto Paranaíba structural high. Diamonds in this region were discovered in the Bagagem River and later in the alluvial deposits of the Santo Antônio do Bonito, Santo Inácio and Douradinho rivers. Diamond-bearing kimberlites observed in the region are the primary sources of diamond deposits, as in the case of the Vargem Bonita diggings-in the upper São Francisco River. However, the primary sources of the alluvial diamonds that occur in the Santo Antônio do Bonito, Santo Inácio, and Douradinho rivers have not been clarified. These diamond populations have characteristics common to all three drainage area, where large stones are frequently recovered. Diamond accumulation in the alluvium is due to the erosion and re-concentration of material from basal conglomerate of the Capacete Formation. There is evidence that the sources that fed the conglomerate are local diamond-bearing kimberlites of approximately 90-120 Ma underlying the Capacete Formation, which in an upper unit of the Mata da Corda Group. Recent fieldwork led to the location of a kimberlite intrusion in the Santo Inácio River Basin, southeast of Coromandel. The intrusion fulfills the requirements constituting a primary source of diamonds in the area.
DS1996-1233
1996
Peirson, N.J.Ryan, C.G., Griffin, W.L., Peirson, N.J.Garnet geotherms: pressure temperature dat a from chromium-pyrope garnet xenocrysts in volcanic rocks.Journal of Geophysical Research, Vol. 101, No. B3, March 10, pp. 5611-26.AustraliaGeothermometry, Volcanics -xenocrysts
DS1995-2130
1995
Peishan, et al.Zhang, Peishan, et al.Occurrences of RE minerals and geology of rare earth elements (REE) ore depositsIn: Mineralogy and geology of rare earths in China, pp. 171-190ChinaRare earths, Carbonatite
DS1995-1468
1995
Peishan, Z.Peishan, Z., et al.Occurrences of Re minerals and geology of rare earth elements (REE) ore depositsMineralogy and Geology of Rare Earths in China, Chapter 8, pp. 171-190.ChinaCarbonatite, Rare earths
DS200712-0607
2007
Peishan, Z.LeBas, M.J., Xueming, Y., Taylor, R.N., Spior, B., Milton, J.A., Peishan, Z.New evidence from a calcite dolomite carbonatite dyke for the magmatic origin of the massive Bayan Obo ore bearing dolomite marble, Inner Mongolia China.Mineralogy and Petrology, Vol. 91, 3-4, pp. 287-China, MongoliaCarbonatite
DS200812-0635
2008
Peishan, Z.Le Bas, M.J., Xueming, Y., Taylor, R.N., Spiro, B., Milton, J.A., Peishan, Z.New evidence from a calcite dolomite carbonatite dyke for the magmatic origin of the massive Bayan Obo ore bearing dolomite marble, Inner Mongolia, China.Mineralogy and Petrology, Vol. 90, 3-4, pp. 223-248.China, MongoliaCarbonatite
DS2001-0903
2001
Peive, A.A.Peive, A.A., et al.Geological fetures of the Sierra Leone fracture zone region, central Atlantic Ocean.Doklady Academy of Sciences, Vol. 3771, March/April pp. 310-13.Sierra LeoneTectonics, Lineaments
DS200512-0992
2005
Peive, A.A.Simonov, V.A., Kovyazin, S.V., Peive, A.A., Kolmogorov, Y.P.Geochemical characteristics of magmatic systems in the region of the Sierra Leone Fracture Zone: central Atlantic: evidence from melt inclusions.Geochemistry International, Vol. 43, 7, pp. 682-693.Africa, Sierra LeoneMagmatism, chemistry
DS200512-0993
2005
Peive, A.A.Simonov, V.A., Kovyazin, S.V., Peive, A.A., Kolmogorov, Yu.P.Geochemical characteristics of magmatic systems in the region of the Sierra Leone Fracture Zone, Central Atlantic: evidence from melt inclusions.Geochemistry International, Vol. 7, 5, pp. 682-Africa, Sierra LeoneMagmatism
DS1989-1190
1989
Peizhen ZhangPeizhen Zhang, Burchfiel, B.C., Shefa Chen, Qidong DengExtinction of pull-apart basinsGeology, Vol. 17, No. 9, September pp. 814-817ChinaBasins, Tectonics
DS1990-0297
1990
Pek, J.Cerv, V., Pek, J.Modelling and analysis of electromagnetic fields in 3D inhomogeneousmediaSurveys in Geophysics, Vol. 11, No. 2-3 September pp. 205-230GlobalGeophysics, Electromagnetic -3D.
DS200812-1037
2008
Pek, J.Semenov, V.Y., Pek, J., et al.Electrical structure of the upper mantle beneath Central Europe: results of the CEMES project.Acta Geophysica, Vol. 56, 4, pp. 957-981.EuropeGeophysics - seismics
DS201112-0100
2011
Pekar, S.F.Boulila, S., Galbrun, B., Miller, K.G., Pekar, S.F., Browning, J.V., Laskar, J., Wright, J.D.On the origin of Cenozoic and Mesozoic 'third order' eustatic sequences.Earth Science Reviews, Vol. 109, 3-4, pp. 94-112.GlobalGeomorphology - sea levels
DS202003-0374
2020
Pekov, I.Zubkova, N.V., Chukanov, N.V., Schaefer, C., Kan, K.V., Pekov, I., Pushcharovsky, D.Yu.A1 analogue of chayesite from a lamproite of Canacarix, SE Spain, and its crystal structure.Journal of Mineralogy and Geochemistry ( formerly Neues Jahrbuch fur Mineralogie), in press NOT availableEurope, Spainlamproite
DS2001-1172
2001
Pekov, I.V.Ulyanov, A.A., Ustinov, V.I., Turchkova, A.G., Pekov, I.V.Oxygen isotope composition of minerals from highly alkalic rocks of the Khibiny Massif ( Kola Peninsula).Moscow University Bulletin, Vol.56,4,pp.56-63.Russia, Kola PeninsulaAlkaline rocks - not specific to diamonds
DS200912-0269
2009
Pekov, I.V.Grigorieva, A.A., Zubkova, N.V., Pekov, I.V., Pushcharvsky, D.Yu.Crystal structure of hilarite from Khibiny alkaline massif ( Kola Peninsula).Doklady Earth Sciences, Vol. 428, 1, pp. 1051-1053.Russia, Kola PeninsulaAlkalic
DS201505-0249
2015
Pekov, I.V.Belogub, E.V., Krivovichev, S.V., Pekov, I.V., Kuznetsov, A.M., Yapaskurt, V.O., Kitlyarov, V.A., Chukanov, N.V., Belakoviskiy, D.I.Nickelpicromerite, K2Ni(SO4)2*6H2O, a new picromerite group mineral from Slyudorudnik, South Urals, Russia.Mineralogy and Petrology, Vol. 109, 2, pp. 143-152.Russia, UralsMineralogy

Abstract: A new picromerite-group mineral, nickelpicromerite, K2Ni(SO4)2 - 6H2O (IMA 2012-053), was found at the Vein #169 of the Ufaley quartz deposit, near the town of Slyudorudnik, Kyshtym District, Chelyabinsk area, South Urals, Russia. It is a supergene mineral that occurs, with gypsum and goethite, in the fractures of slightly weathered actinolite-talc schist containing partially vermiculitized biotite and partially altered sulfides: pyrrhotite, pentlandite, millerite, pyrite and marcasite. Nickelpicromerite forms equant to short prismatic or tabular crystals up to 0.07 mm in size and anhedral grains up to 0.5 mm across, their clusters or crusts up to 1 mm. Nickelpicromerite is light greenish blue. Lustre is vitreous. Mohs hardness is 2-2½. Cleavage is distinct, parallel to {10-2}. Dmeas is 2.20(2), Dcalc is 2.22 g cm?3. Nickelpicromerite is optically biaxial (+), ? = 1.486(2), ? = 1.489(2), ? = 1.494(2), 2Vmeas =75(10)°, 2Vcalc =76°. The chemical composition (wt.%, electron-microprobe data) is: K2O 20.93, MgO 0.38, FeO 0.07, NiO 16.76, SO3 37.20, H2O (calc.) 24.66, total 100.00. The empirical formula, calculated based on 14 O, is: K1.93Mg0.04Ni0.98S2.02O8.05(H2O)5.95. Nickelpicromerite is monoclinic, P21/c, a = 6.1310(7), b = 12.1863(14), c = 9.0076(10) Å, ? = 105.045(2)°, V = 649.9(1) Å3, Z = 2. Eight strongest reflections of the powder XRD pattern are [d,Å-I(hkl)]: 5.386--34(110); 4.312-46(002); 4.240-33(120); 4.085--100(012, 10-2); 3.685-85(031), 3.041-45(040, 112), 2.808-31(013, 20-2, 122), 2.368-34(13-3, 21-3, 033). Nickelpicromerite (single-crystal X-ray data, R = 0.028) is isostructural to other picromerite-group minerals and synthetic Tutton’s salts. Its crystal structure consists of [Ni(H2O)6]2+ octahedra linked to (SO4)2? tetrahedra via hydrogen bonds. K+ cations are coordinated by eight anions. Nickelpicromerite is the product of alteration of primary sulfide minerals and the reaction of the acid Ni-sulfate solutions with biotite.
DS201609-1729
2016
Pekov, I.V.Lykova, I.S., Pekov, I.V., Chukanov, N.V., Belakovskiy, D.I., Yapaskurt, V.O., Zubkova, N.V., Britvin, S.N., Giester, G.Calciomurmanite a new mineral from the Lovozero and Khibiny alkaline complexes, Kola Peninsula.European Journal of Minerlogy, in press avaialbe 15p.RussiaMineralogy
DS201904-0766
2018
Pekov, I.V.Pekov, I.V., Zubkova, N.V., Yapaskurt, V.O., Lykova, I.S., Chukanov, N.V., Belakovskiy, D.I., Britvin, S.N., Turchkova, A.G., Pushcharovsky, D.Y.Alexhomyakovite, K6(Ca2Na) (CO3)5CI.6h2O, a new mineral from the Khibiny alkaline complex, Kola Peninsula, Russia.European Journal of Mineralogy, Vol. 31, pp. 13-143.Russia, Kola Peninsuladeposit - Khibiny

Abstract: The new mineral alexkhomyakovite K6(Ca2Na)(CO3)5Cl?6H2O (IMA2015-013) occurs in a peralkaline pegmatite at Mt. Koashva, Khibiny alkaline complex, Kola peninsula, Russia. It is a hydrothermal mineral associated with villiaumite, natrite, potassic feldspar, pectolite, sodalite, biotite, lamprophyllite, titanite, fluorapatite, wadeite, burbankite, rasvumite, djerfisherite, molybdenite and an incompletely characterized Na-Ca silicate. Alexkhomyakovite occurs as equant grains up to 0.2 mm, veinlets up to 3 cm long and up to 1 mm thick and fine-grained aggregates replacing delhayelite. Alexkhomyakovite is transparent to translucent, colourless, white or grey, with vitreous to greasy lustre. It is brittle, the Mohs hardness is ca. 3. No cleavage was observed, the fracture is uneven. D meas = 2.25(1), D calc = 2.196 g cm?3. Alexkhomyakovite is optically uniaxial (-), ? = 1.543(2), ? = 1.476(2). The infrared spectrum is reported. The chemical composition [wt%, electron microprobe data, CO2 and H2O contents calculated for 5 (CO3) and 6 (H2O) per formula unit (pfu), respectively] is: Na2O 4.09, K2O 35.72, CaO 14.92, MnO 0.01, FeO 0.02, SO3 0.11, Cl 4.32, CO2 28.28, H2O 13.90, -O=Cl -0.98, total 100.39. The empirical formula calculated on the basis of 9 metal cations pfu is K5.90Ca2.07Na1.03(CO3)5(SO4)0.01O0.05Cl0.95?6H2O. The numbers of CO3 groups and H2O molecules are based on structure data. Alexkhomyakovite is hexagonal, P63/mcm, a = 9.2691(2), c = 15.8419(4) Å, V = 1178.72(5) Å3 and Z = 2. The strongest reflections of the powder X-ray diffraction pattern [d Å(I)(hkl)] are: 7.96(27)(002), 3.486(35)(113), 3.011(100)(114), 2.977(32)(211), 2.676(36)(300), 2.626(42)(213, 115), 2.206(26)(311) and 1.982(17)(008). The crystal structure (solved from single-crystal X-ray diffraction data, R = 0.0578) is unique. It is based on (001) heteropolyhedral layers of pentagonal bipyramids (Ca,Na)O5(H2O)2 interconnected via carbonate groups of two types, edge-sharing ones and vertex-sharing ones. Ca and Na are disordered. Ten-fold coordinated K cations centre KO6Cl(H2O)3 polyhedra on either side of the heteropolyhedral layer. A third type of carbonate group and Cl occupy the interlayer. The mineral is named in honour of the outstanding Russian mineralogist Alexander Petrovich Khomyakov (1933-2012).
DS202008-1462
2020
Pekov, I.V.Zubkova, N.V., Chukanov, N.V., Schafer, C., van Konstantin, V., Pekov,I.V., Pushcharovsky, D. Yu.Al analogue of chayvesite from a lamproite of Cancarix, SE Spain, and its crystal structure.Neues Jahbuch fur Mineralogie, Vol. 196, 3, pp. 193-196.Europe, Spainlamproite

Abstract: Al analogue of chayesite (with Al > Fe3+) was found in a lamproite from Cancarix, SE Spain. The mineral forms green thick-tabular crystals up to 0.4 mm across in cavities. The empirical formula derived from EMP measurements and calculated on the basis of 17 Mg + Fe + Al + Si apfu is (K0.75 Na0.20 Ca0.11)Mg3.04 Fe0.99 Al1.18 Si11.80 O30. The crystal structure was determined from single crystal X-ray diffraction data ( R = 2.38%). The mineral is hexagonal, space group P 6/ mcc, a = 10.09199(12), c = 14.35079(19) Å, V = 1265.78(3) Å3, Z = 2. Fe is predominantly divalent. Al is mainly distributed between the octahedral A site and the tetrahedral T 2 site. The crystal chemical formula derived from the structure refinement is C (K0.73 Na0.16 Ca0.11) B (Na0.02)4 A (Mg0.42 Al0.29 Fe0.29)2 T 2(Mg0.71 Fe0.16 Al0.13)3 T 1(Si0.985 Al0.015)12 O30.
DS202011-2036
2020
Pekov, I.V.Chukanov, N.V., Aksenov, S.M., Pekov, I.V., Belakovskiy, D.I., Vozchikova, S.A., Britvin, S.N.Sergevanite, new eudialyte group mineral from the Lovozero alkaline massif, Kola Peninsula.The Canadian Mineralogist, Vol. 58, pp. 421-436.Russia, Kola Peninsuladeposit - Lovozero

Abstract: The new eudialyte-group mineral sergevanite, ideally Na15(Ca3Mn3)(Na2Fe)Zr3Si26O72(OH)3•H2O, was discovered in highly agpaitic foyaite from the Karnasurt Mountain, Lovozero alkaline massif, Kola Peninsula, Russia. The associated minerals are microcline, albite, nepheline, arfvedsonite, aegirine, lamprophyllite, fluorapatite, steenstrupine-(Ce), ilmenite, and sphalerite. Sergevanite forms yellow to orange-yellow anhedral grains up to 1.5 mm across and the outer zones of some grains of associated eudialyte. Its luster is vitreous, and the streak is white. No cleavage is observed. The Mohs' hardness is 5. Density measured by equilibration in heavy liquids is 2.90(1) g/cm3. Calculated density is equal to 2.906 g/cm3. Sergevanite is nonpleochroic, optically uniaxial, positive, with ? = 1.604(2) and ? = 1.607(2) (? = 589 nm). The infrared spectrum is given. The chemical composition of sergevanite is (wt.%; electron microprobe, H2O determined by HCN analysis): Na2O 13.69, K2O 1.40, CaO 7.66, La2O3 0.90, Ce2O3 1.41, Pr2O3 0.33, Nd2O3 0.64, Sm2O3 0.14, MnO 4.15, FeO 1.34, TiO2 1.19, ZrO2 10.67, HfO2 0.29, Nb2O5 1.63, SiO2 49.61, SO3 0.77, Cl 0.23, H2O 4.22, -O=Cl -0.05, total 100.22. The empirical formula (based on 25.5 Si atoms pfu, in accordance with structural data) is H14.46Na13.64K0.92Ca4.22Ce0.27La0.17Nd0.12Pr0.06Sm0.02Mn1.81Fe2+0.58Ti0.46Zr2.67Hf0.04Nb0.38Si25.5S0.30Cl0.20O81.35. The crystal structure was determined using single-crystal X-ray diffraction data. The new mineral is trigonal, space group R3, with a = 14.2179(1) Å, c = 30.3492(3) Å, V = 5313.11(7) Å3, and Z = 3. In the structure of sergevanite, Ca and Mn are ordered in the six-membered ring of octahedra (at the sites M11 and M12), and Na dominates over Fe2+ at the M2 site. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 7.12 (70) (110), 5.711 (43) (202), 4.321 (72) (205), 3.806 (39) (033), 3.551 (39) (220, 027), 3.398 (39) (313), 2.978 (95) (?forumla?), 2.855 (100) (404). Sergevanite is named after the Sergevan' River, which is near the discovery locality.
DS202203-0339
2021
Pekov, I.V.Christy, A.G., Pekov, I.V., Krivobichev, S.V.The distinctive mineralogy of carbonatites.Elements, Vol. 17, pp. 333-338.Mantlemagmatism

Abstract: The mineralogy of carbonatites reflects both the diversity of the sources of their parent magmas and their unusual chemistry. Carbonatites contain diverse suites of both primary magmatic minerals and later hydrothermal products. We present a summary of the variety of minerals found in carbon-atites, and note the economic importance of some of them, particularly those that are major sources of "critical elements", such as Nb and rare earth elements (REEs), which are essential for modern technological applications. Selected mineral groups are then discussed in detail: the REE carbonates, the alkali-rich ephemeral minerals that are rarely preserved but that may be important in the petrogenesis of carbonatites and their metasomatic haloes in adjacent rocks, and the Nb-rich oxides of the pyrochlore supergroup.-
DS200512-0835
2005
Pele Mountain ResourcesPele Mountain ResourcesBrief mention of diamond activity.Mineweb, Oct. 28, 1p.Canada, OntarioNews item - Pele Mountain Resources
DS200612-1065
2005
Pele Mountain ResourcesPele Mountain ResourcesPele Mountain's 500 tonne Festival bulk sample advances to processing stage.Mineweb, Nov. 2, 2p.Canada, Ontario, WawaNews item - Pele Mountain
DS1991-1325
1991
Pelechaty, S.M.Pelechaty, S.M., James, N.P., Kerans, C., Grotzinger, J.P.A middle Proterozoic paleokarst unconformity and associated sedimentaryrocks, Elu basin, Northwest CanadaSedimentology, Vol. 38, No. 5, October pp. 775-798Northwest TerritoriesBasin, Proterozoic
DS1996-1094
1996
Pelechaty, S.M.Pelechaty, S.M.Stratigraphic evidence for the Siberia -Laurentia connection and early Cambrian rifting.Geology, Vol. 24, No. 8, August pp. 719-722.RussiaCraton, Continental rifting
DS1996-1095
1996
Pelechaty, S.M.Pelechaty, S.M.Stratigraphic evidence for the Siberia Laurentia connection and early Cambrian rifting.Geology, Vol. 24, pp. 719-722.Russia, Siberia, Anabar shield, Baffin Island , Victoria IslandStratigraphy, Rifting
DS1996-1096
1996
Pelechaty, S.M.Pelechaty, S.M., et al.Chemostratigraphic and sequence stratigraphic constraints on Vendian-Cambrian basin dynamics..cratonJournal of Geology, Vol. 104, pp. 543-63.Russia, SiberiaCraton - stratigraphy
DS1996-1097
1996
Pelevhaty, S.M.Pelevhaty, S.M., Grotzinger, J.P., Kashirtsev, V.A., et al.Chemostratigraphic and sequence stratigraphic constraints on Vendian Cambrian basin dynamics.Journal of Geology, Vol. 104, No. 5, Sept. pp. 543-563.Russia, SiberiaBasin development, Craton -Siberia
DS1985-0522
1985
Pell, J.Pell, J.Carbonatites and Related Rocks in British ColumbiaBritish Columbia Department of Mines Geol. Fieldwork, 1985-1, PP. 84-94.Canada, British ColumbiaCarbonatite
DS1986-0375
1986
Pell, J.Hoy, T., Pell, J.Carbonatites and associated alkalic rocks Perry River and MountGraceareas, Shuswap Complex, southeastern British ColumbiaBritish Columbia Ministry of Energy, Geological Fieldwork 1985, Paper No. 1986-1, pp. 69-87British ColumbiaCarbonatite, Alkaline rocks
DS1986-0635
1986
Pell, J.Pell, J.Diatreme breccias in British ColumbiaBritish Columbia Ministry of Energy, Geological Fieldwork 1985, Paper No. 1986-1, ppBritish ColumbiaCarbonatite
DS1986-0636
1986
Pell, J.Pell, J.Carbonatites in British Columbia: the Alley propertyBritish Columbia Ministry of Energy, Geological Fieldwork 1985, Paper No. 1986-1, pp. 275-277British ColumbiaCarbonatite
DS1987-0573
1987
Pell, J.Pell, J.Alkalic ultrabasic diatremes in British Columbia: petrology,geochronology and tectonic significanceBritish Columbia Geological Fieldwork 1986, Paper No. 1987-1, pp. 259-272British ColumbiaCarbonatite, Alkaline rocks
DS1987-0574
1987
Pell, J.Pell, J.Alkaline ultrabasic rocks in British Columbia: carbonatites,nephelinesyenites, kimberlites, ultramafic lamprophyres And related rocksBritish Columbia Department of Mines Open file, No. 1987-17, 109p. 25 maps 12 tables $ 10.00British ColumbiaKimberlites, Carbonatite
DS1989-1191
1989
Pell, J.Pell, J.Carbonatites in British ColumbiaBritish Columbia Ministry of Energy, Mines, and Petroleum Resources, No. 1989-1, p. 2British ColumbiaCarbonatite, Mount Grace, Ice River, Ale
DS1989-1192
1989
Pell, J.Pell, J., Fox, M.The Kechika yttrium and rare earth prospectBritish Columbia Ministry of Energy, Mines, and Petroleum Resources, Geological Fieldwork Report 1989-1, pp. 417-421British ColumbiaAlkaline igneous, rare earth elements (REE).
DS1989-1193
1989
Pell, J.Pell, J., Hoy, T.Carbonatites in a continental margin environment the Canadian CordilleraCarbonatites -Genesis and Evolution, Ed. K. Bell Unwin Hyman Publ, pp. 200-220British ColumbiaCarbonatite, Localities, Tectonics
DS1993-1215
1993
Pell, J.Pell, J.Great Slave Plain... diamondsNorthwest Territories Exploration Overview for 1993, November p. 16.Northwest TerritoriesCompany activities to date, Map
DS1993-1216
1993
Pell, J.Pell, J.Slave structural province: diamondsNorthwest Territories Exploration Overview for 1993, November pp. 10-15.Northwest TerritoriesCompany activities to date, Map
DS1993-1217
1993
Pell, J.Pell, J.Arctic Islands... diamondsNorthwest Territories Exploration Overview for 1993, November pp. 16-17.Northwest TerritoriesCompany activities to date, Map
DS1993-1218
1993
Pell, J.Pell, J.New kimberlite discoveries on Somerset Island, northwest Territories #3Northwest Territories Exploration Overview for 1993, November pp. 47.Northwest TerritoriesSomserset Island, Kimberlites
DS1993-1219
1993
Pell, J.Pell, J.New kimberlite discoveries on Somerset Island, northwest Territories #3Northwest Territories Geoscience Forum preprint, 1p.Northwest Territories, Somerset IslandNews item
DS1994-1351
1994
Pell, J.Pell, J.Carbonatites, nepheline syenites, kimberlites and related rocks in British Columbia #1British Columbia Mines, Bulletin. No. 88, 154p. $ 40.00British ColumbiaCarbonatite, Kimberlites
DS1994-1352
1994
Pell, J.Pell, J.Carbonatites, nepheline syenites, kimberlites and related rocks in BritishColumbia. #2British Columbia Geological Survey, Bulletin. No. 88, $ 40.00British ColumbiaCarbonatite, kimberlites, Alkaline rocks
DS1994-1353
1994
Pell, J.Pell, J.New kimberlite discoveries on Somerset Island, northwest Territories #2Geological Association of Canada (GAC) Abstract Volume, Vol. 19, p. PosterNorthwest TerritoriesKimberlite update, Somerset Island
DS1994-1354
1994
Pell, J.Pell, J.Kimberlites and diamond exploration in the Northwest TerritoriesGeological Survey of Canada Open Forum January 17-19th. Abstracts only, p. 29.Northwest TerritoriesKimberlite, Diamond activities
DS1994-1355
1994
Pell, J.Pell, J.Kimberlites and diamond exploration in the Central Slave Province, northwest Territories75M, N, 76C, D.E.F, 85P, 86A, H.Indian and Northern Affairs, northwest Territories Geology Division, No. EGS 1994-7 map 1: 500, 000 colour $ 15.00Northwest TerritoriesMap -kimberlites and diamond exploration, Central Slave province
DS1994-1356
1994
Pell, J.Pell, J.Arctic Islands : diamondsNorthwest Territories 1994 Open House Abstracts, p. 17. abstractNorthwest TerritoriesNews item, Arctic Bathrust, Baffin
DS1994-1357
1994
Pell, J.Pell, J.Slave structural province and surrounding region : diamondsNorthwest Territories 1994 Open House Abstracts, pp. 11-16.Northwest TerritoriesNews item, Slave structural province update
DS1994-1358
1994
Pell, J.Pell, J.Kimberlites and diamond exploration in the Slave structural province northwest TerritoriesNorthwest Territories Geoscience Forum preprint, 5p.Northwest Territories, Baffin IslandNews item, Exploration activity
DS1994-1359
1994
Pell, J.Pell, J.New kimberlite discoveries on Somerset Island, northwest Territories #1The Gangue (MDD Newsletter), No. 45, May pp. 1, 2.Northwest Territories, Somerset IslandUpdate on exploration, Sampling results -old
DS1995-1469
1995
Pell, J.Pell, J.Kimberlites and diamond exploration in the Central Slave Province, northwest Territories NTS75 M, N, 76 C-F, 86AH, 85P.northwest Territories Geology Division, DIAND., EGS 1995-01 1 map 1:500, 000.Northwest TerritoriesExploration - assessment compilation
DS1995-1470
1995
Pell, J.Pell, J.Overview of kimberlites in the northwest TerritoriesYellowknife 95, program and abstracts, Sept. 6-8, p. 34-35.Northwest TerritoriesOverview
DS1996-0661
1996
Pell, J.Ijewliw, O.J., Pell, J.Diatreme breccias in the CordilleraGeological Survey of Canada, LeCheminant ed, OF 3228, pp. 91-95.British Columbia, Northwest TerritoriesDiatreme breccias, Lithology
DS1996-1098
1996
Pell, J.Pell, J.Mineral deposits associated with carbonatites and related alkaline igneousrocks.Mineralogical Association of Canada Short Course, Vol. 24, pp. 271-310.GlobalCarbonatite, Economics
DS1996-1099
1996
Pell, J.Pell, J.The geology of kimberlites in the Slave Province: a preliminary reviewGeological Survey of Canada Colloquium, Jan. 22-24th., Poster display onlyNorthwest TerritoriesExploration, Overview
DS1996-1100
1996
Pell, J.Pell, J.Slave diamondsnorthwest Territories Exploration overview 1995, March pp. 2-6-2-12.Northwest TerritoriesNews item, Update and overview company activity
DS1996-1101
1996
Pell, J.Pell, J.Slave structural province -diamonds... overview... companies and year'sprogress.Northwest Territories Exploration Overview, Nov. 26, p.2-4 - 2-8.Northwest TerritoriesProgress update, Company activities
DS1996-1102
1996
Pell, J.Pell, J.Arctic Islands... overview and covers diamond activitiesNorthwest Territories Exploration Overview, Nov. 26, p.2-10 -10a.Northwest Territories, Victoria IslandProgress update, Company activities
DS1998-1147
1998
Pell, J.Pell, J.Kimberlite indicator database, includes pipe locations, sampling, mini-bulk,bulk, geology, mineralogy, ...northwest Territories Geology Division, DIAND., EGS 1998-013 1 map 1:500, 000. spreadsheetNorthwest TerritoriesExploration - assessment compilation
DS1999-0548
1999
Pell, J.Pell, J.Prospecting for kimberlites in the semi-arid tropics: a case study from the Aredor concession Republic GuineaAssocation of Exploration Geologists (AEG) 19th. Diamond Exploration Methods Case Histories, pp. 43-55GuineaGeochemistry, arid, weathering, Aredor concession case study
DS2000-0752
2000
Pell, J.Pell, J., Schimann, K.Prospecting for kimberlites in peritropical regions using heavy minerals: a case study from Aredor concess.Geological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) Calgary May 2000, 4p.GuineaLateritic environments, saprolite, case history, Deposit - K23
DS2003-1057
2003
Pell, J.Pell, J.The Nanuq diamond project, western Churchill Province: poised for discovery31st Yellowknife Geoscience Forum, p. 78. (abst.)NunavutGeochemistry
DS2003-1058
2003
Pell, J.Pell, J., Ijewliw, O.Kimberlites, melnoites and Look alikes in British Columbia CanadaBritish Columbia Geological Survey, large posterBritish ColumbiaOverview
DS200412-1517
2003
Pell, J.Pell, J.The Nanuq diamond project, western Churchill Province: poised for discovery.31st Yellowknife Geoscience Forum, p. 78. (abst.)Canada, NunavutGeochemistry
DS200412-1518
2003
Pell, J.Pell, J., Ijewliw, O.Kimberlites, melnoites and Look alikes in British Columbia Canada.British Columbia Geological Survey, large posterCanada, British ColumbiaOverview
DS200512-0272
2004
Pell, J.Ettinger, A., Pell, J., Carter, A.When mergers make sense: the new Peregrine Diamonds Ltd.32nd Yellowknife Geoscience Forum, Nov. 16-18, p.24-25. (talk)Canada, NunavutCompany overview, BHP Billiton
DS200612-0278
2006
Pell, J.Coopersmith, H., Pell, J., Scott Smith, B.The importance of kimberlite geology in diamond deposit evaluation: a case study of DO27/DO18 kimberlite, NWT, Canada.Emplacement Workshop held September, 5p. extended abstractCanada, Northwest TerritoriesDeposit - DO27/DO18 - case history, models
DS200612-0529
2006
Pell, J.Harder, M., Hetman, C., Scott Smith, B., Pell, J.Geology of the DO27 pipe: a pyroclastic kimberlite in the Lac de Gras Province, NWT, Canada.Emplacement Workshop held September, 5p. extended abstractCanada, Northwest TerritoriesDeposit - DO27, geology
DS200612-0598
2006
Pell, J.Holmes, P., Pell, J., Mathison, W., Strickland, D., Harder, M.New sparkle at the DO-27 diamond project.CIM Conference and Exhibition, Vancouver - Creating Value with Values, List of talks CIM Magazine, Feb. p. 78.Canada, Northwest TerritoriesOverview - Peregrine
DS200612-1066
2005
Pell, J.Pell, J., et al.Peregrine Diamonds - DO 27: a new chapter in an evolving story.32ndYellowknife Geoscience Forum, p. 54 abstractCanada, Northwest TerritoriesUpdate - Peregrine
DS200612-1067
2006
Pell, J.Pell, J.New promise in old pipe: the DO-27 story, NWT.Prospectors and Developers Association of Canada, March 1p. abstractCanada, Northwest TerritoriesHistory - Tli Kwi Cho
DS200712-0412
2006
Pell, J.Harder, M., Hetman, C., Scott Smith, B., Pell, J.Geology model of the DO27 pipe.34th Yellowknife Geoscience Forum, p. 82. abstractCanada, Northwest TerritoriesTli Kwi Cho complex
DS200712-0413
2007
Pell, J.Harder, M., Pell, J.Geology of the DO-27 kimberlite pipe.Geological Association of Canada, Gac-Mac Yellowknife 2007, May 23-25, Volume 32, 1 pg. abstract p.37.Canada, Northwest TerritoriesPetrology
DS200812-0483
2008
Pell, J.Holmes, P.K., Grenon, H., Self, M.V., Pell, J., Neilson, S.The Chidliak property, a new diamond district on Baffin Island, Nunavut.Northwest Territories Geoscience Office, p. 35. abstractCanada, Nunavut, Baffin IslandBrief overview - Peregrine
DS200812-0876
2007
Pell, J.Pell, J., Mathison, W., Friedland, E.V., Crawford, J.DO-27 and beyond: an update on Peregrine Diamonds programs in the Slave Province.35th. Yellowknife Geoscience Forum, Abstracts only p. 46-47.Canada, Northwest TerritoriesExploration - overview
DS200912-0279
2009
Pell, J.Harder, M., Scott Smith, B.H., Hetman, C.M., Pell, J.The evolution of geological models for the DO-27 kimberlite, NWT Canada: implications for evaluation.Lithos, In press - available 38p.Canada, Northwest TerritoriesDeposit - DO-27
DS200912-0310
2009
Pell, J.Holmes, P., Pell, J., Clements, B., Grenon, H., Sell, M.The Chidliak diamond project, Baffin Island, one year after initial discovery.37th. Annual Yellowknife Geoscience Forum, Abstracts p. 24.Canada, Nunavut, Baffin IslandHistory
DS200912-0578
2009
Pell, J.Pell, J.Chidliak: Canada's newest diamond district.PDAC 2009, 1p. abstractCanada, NunavutExploration overview
DS201012-0572
2010
Pell, J.Pell, J.The Chidliak diamond district, Nunavut: 50 kimberlites and counting. Peregrine38th. Geoscience Forum Northwest Territories, Abstract p. 77.Canada, Nunavut, Baffin IslandChidliak
DS201112-0776
2011
Pell, J.Pell, J.The Chidliak diamond district, Nunavut: 50 kimberlites and counting.PDAC 2011, Monday March 7, 1/2p. abstractCanada, NunavutGeology and overview
DS201212-0295
2012
Pell, J.Herman, L.M., Grutter, H.S., Pell, J., Holmes, P., Grenon, H.U-Pb geochronology , SR and ND isotope compositions of groundmass perovskite from the Chidliak and Qilaq kimberlites, Baffin Island, Nunavut.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractCanada, Nunavut, Baffin IslandDeposit - Chidliak, Qilaq
DS201212-0515
2012
Pell, J.Neilson, S., Grutter, H., Pell, J., Grenon, H.The evolution of kimberlite indicator mineral interpretation on the Chidliak project, Baffin Island, Nunavut.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractCanada, Nunavut, Baffin IslandDeposit - Chidliak
DS201212-0548
2012
Pell, J.Pell, J., Grutter, H., Grenon, H., Dempsey, S., Neilson, S.Exploration and discovery of the Chidliak kimberlite province, Baffin Island, Nunavut: Canada's newest diamond district.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractCanada, Nunavut, Baffin IslandDeposit - Chidliak
DS201312-0391
2013
Pell, J.Hitchie, L., Pell, J., Scott Smith, B.H., Russell, J.K.The CH-6 kimberlite, Canada: textural and mineralogical features and their relevance to volcanic facies and magma batch interpretation.GAC-MAC 2013 SS4: Diamond: from birth in the mantle to emplacement in kimberlite, abstract onlyCanada, Nunavut, Baffin IslandDeposit - CH-6
DS201312-0645
2013
Pell, J.Nichols, K., Stachel, T., Pell, J., Mate, D.Diamond sources beneath the Hall Peninsula, Nunavut: a preliminary assessment based on micro-diamonds.Geoscience Forum 40 NWT, Poster abstract only p. 64Canada, Nunavut, Baffin IslandDeposit - Chidliak
DS201312-0646
2013
Pell, J.Nichols, K., Stachel, T., Stern, R.A., Pell, J., Mate, D.Diamond sources beneath the Hall Peninsula, Nunavut: a preliminary assessment based on micro-diamonds.GAC-MAC 2013 SS4: Diamond: from birth in the mantle to emplacement in kimberlite, abstract onlyCanada, Nunavut, Hall PeninsulaMicrodiamonds
DS201312-0695
2013
Pell, J.Pell, J., Clements, B., Grutter, H., Neilson, S., Grenon, H.Following kimberlite indicator minerals to source in the Chidliak kimberlite province, Nunavut.PDAC 2013 , 6p.Canada, Nunavut, Baffin IslandIndicator Mineralogy
DS201312-0696
2013
Pell, J.Pell, J., Clements, B., Grutter, H., Neilson, S., Grenon, H.Following kimberlite indicator minerals to source in the Chidliak kimberlite province, Nunavut.GSC Open file 7374 Ftp2.cits.rncan.gc.ca, pp. 47-52.Canada, Nunavut, Baffin IslandDeposit - Chidliak
DS201312-0697
2013
Pell, J.Pell, J., Grutter, H., Neilson, S.Exploration and discovery of the Chidliak kimberlite province, Baffin Island, Nunavut: Canada's newest diamond district.Proceedings of the 10th. International Kimberlite Conference, Vol. 2, Special Issue of the Journal of the Geological Society of India,, Vol. 2, pp. 209-227.Canada, Nunavut, Baffin IslandDeposit - Chidliak
DS201312-0698
2013
Pell, J.Pell, J., Russell, K., Zhang, S.Kimberlite emplacement temperatures from conodont geothermometry; hotter than you might think.Vancouver Kimberlite Cluster, abstract talk Oct. 18, 1/2p.Canada, NunavutGeothermometry
DS201312-1011
2013
Pell, J.Zhang, S., Pell, J.Study of sedimentary rock xenoliths from kimberlites on Hall Peninsula, Baffin Island, Nunavut.Canada-Nunavut Geoscience Summary of Activities 2012, pp. 107-112.Canada, Nunavut, Baffin IslandDeposit - Chidliak
DS201412-0670
2013
Pell, J.Pell, J., Grutter, H., Neilson, S., Lockhart, G., Dempsey, S., Grenon, H.Exploration and discovery of the Chidliak kimberlite province, Baffin Island, Nunavut: Canada's newest diamond district.Proceedings of the 10th. International Kimberlite Conference, Vol. 2, pp. 209-228.Canada, Nunavut, Baffin IslandDeposit - Chidliak area
DS201412-1025
2014
Pell, J.Zhang, S., Pell, J.Conodonts recovered from the carbonate xenoliths in the kimberlites confirm the Paleozoic cover on the Hall Peninsula.Canadian Journal of Earth Sciences, Vol. 51, pp. 142-155.Canada, Nunavut, Baffin IslandDeposit - Chidliak
DS201501-0024
2015
Pell, J.Pell, J., Russell, J.K., Zhang, S.Kimberlite emplacement temperatures from conodont geothermometry.Earth and Planetary Science Letters, Vol. 411, pp. 131-141.Canada, Nunavut, Baffin IslandDeposit - Chidliak
DS201501-0025
2015
Pell, J.Pell, J.Building the diamond resource at Chidliak, Baffin Island, Nunavut.PDAC 2015, 1p. AbstractCanada, Nunavut, Baffin IslandDeposit - Chidliak
DS201504-0201
2015
Pell, J.Heaman, L.M., Pell, J., Grutter, H.S., Creaser, R.A.U-Pb geochronology and Sr/Nd isotope compositions of groundmass perovskite from the newly discovered Jurassic Chidliak kimberlite field, Baffin Island, Canada.Earth and Planetary Science Letters, Vol. 415, April pp. 183-189.Canada, Nunavut, Baffin IslandDeposit - Chidliak
DS201611-2130
2016
Pell, J.Pell, J., Grutter, H.Comments and observations on public-domain micro/macro diamond datasets.Vancouver Kimberlite Cluster, Nov. 8, 1/2p. AbstractTechnologyMicrodiamonds
DS201704-0654
2016
Pell, J.Zhang, S., Pell, J.Conodonts and their colour alteration index values from carbonate xenoliths in four kimberlites on the Hall Peninsula, Baffin Island, Nunavut.Canada-Nunavut Geoscience Office, pp. 1-12.Canada, Nunavut, Baffin IslandDeposit - Chidliak
DS201708-1731
2017
Pell, J.Pell, J.Conodont geothermometry in pyroclastic kimberlite: constraints on emplacement temperature and cooling histories.11th. International Kimberlite Conference, PosterCanada, Nunavut, Baffin IslandGeothermometry

Abstract: Kimberlites are mantle-derived ultramafic rocks preserved in volcanic and sub-volcanic edifices and are the main primary source of diamonds. The temperatures of formation, transport, eruption and deposition remain poorly constrained despite their importance for understanding the petrological and thermodynamic properties of kimberlite magmas and styles of volcanic eruption. Here, we present measured values of Colour Alteration Indices (CAI) for conodonts recovered from 76 Paleozoic carbonate xenoliths found within 11 pipes from the Chidliak kimberlite field on Baffin Island, Nunavut, Canada. The dataset comprises the largest range of CAI values (1.5 to 8) and the highest CAI values reported to date for kimberlite-hosted xenoliths. Thermal models for cooling of the Chidliak kimberlite pipes and synchronous heating of conodont-bearing xenoliths indicate time windows of 10–20 000 h and, for these short time windows, the measured CAI values indicate heating of the xenoliths to temperatures of 225 to >925 ?C. We equate these temperatures with the minimum temperatures of the conduit-filling kimberlite deposit (i.e. emplacement temperature, TE). The majority of the xenoliths record CAI values of between 5 and 6.5 suggesting heating of xenoliths to temperatures of 460 ?C–735 ?C. The highest CAI values are consistent with being heated to 700 ?C–925 ?C and establish the minimum conditions for welding or formation of clastogenic kimberlite deposits. Lastly, we use TE variations within and between individual pipes, in conjunction with the geology of the conduit-filling deposits, to constrain the styles of explosive volcanic eruption.
DS201708-1732
2017
Pell, J.Pell, J.A tale of two pipes: using whole rock geochemistry to see through alteration and contamination at the CH-6 & CH-7 kimberlites, Chidliak kimberlite province, Baffin Island, Nunavut.11th. International Kimberlite Conference, PosterCanada, Nunavut, Baffin IslandDeposit - Chidliak
DS201804-0727
2018
Pell, J.Pell, J., Russell, J.K., Zhang, S.Z.Conodont geothermometry in pyroclastic kimberlite: constraints on emplacement temperatures and cooling histories.Mineralogy and Petrology, in press available 14p.Canada, Nunavut, Baffin Islanddeposit - Chidliak

Abstract: Kimberlite pipes from Chidliak, Baffin Island, Nunavut, Canada host surface-derived Paleozoic carbonate xenoliths containing conodonts. Conodonts are phosphatic marine microfossils that experience progressive, cumulative and irreversible colour changes upon heating that are experimentally calibrated as a conodont colour alteration index (CAI). CAI values permit us to estimate the temperatures to which conodont-bearing rocks have been heated. Conodonts have been recovered from 118 samples from 89 carbonate xenoliths collected from 12 of the pipes and CAI values within individual carbonate xenoliths show four types of CAI distributions: (1) CAI values that are uniform throughout the xenolith; (2) lower CAIs in core of a xenolith than the rim; (3) CAIs that increase from one side of the xenolith to the other; and, (4) in one xenolith, higher CAIs in the xenolith core than at the rim. We have used thermal models for post-emplacement conductive cooling of kimberlite pipes and synchronous heating of conodont-bearing xenoliths to establish the temperature-time history of individual xenoliths within the kimberlite bodies. Model results suggest that the time-spans for xenoliths to reach the peak temperatures recorded by CAIs varies from hours for the smallest xenoliths to 2 or 3 years for the largest xenoliths. The thermal modelling shows the first three CAI patterns to be consistent with in situ conductive heating of the xenoliths coupled to the cooling host kimberlite. The fourth pattern remains an anomaly.
DS1986-0637
1986
Pell, J.A.Pell, J.A.Carbonatites in British Columbia: a reviewGeological Association of Canada (GAC) Annual Meeting, Vol. 11, p. 113. AbstractBritish ColumbiaCarbonatite
DS1993-1220
1993
Pell, J.A.Pell, J.A., Atkinson, D.Kimberlites and diamonds in the Northwest Territories -explorationhighlights.The Canadian Mining and Metallurgical Bulletin (CIM Bulletin) , Annual Meeting Abstracts approximately 10 lines, Vol. 86, No. 968, March POSTER ABSTRACT p. 68.Northwest TerritoriesLac de Gras area overview
DS1993-1221
1993
Pell, J.A.Pell, J.A., Atkinson, D.Northwest Territories kimberlites and diamonds: exploration highlights andimplications.Mid-continent diamonds Geological Association of Canada (GAC)-Mineralogical Association of Canada (MAC) Symposium ABSTRACT volume, held Edmonton May, pp. 89-94.Northwest TerritoriesOverview of activities
DS1995-0840
1995
Pell, J.A.Ijewliw, O.J., Pell, J.A.The petrology of pre-orogenic alkaline and ultramafic lamprophyre diatremesin the Cordillera near Golden.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 245-247.British ColumbiaDiatremes, Bush River, Mons Creek, Valenciennes, Lens, Campbell
DS1995-1471
1995
Pell, J.A.Pell, J.A.Kimberlites in the Slave structural province, Northwest Territories: apreliminary review.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 433-435.Northwest TerritoriesOverview, Deposit -Lac de Gras
DS1995-1472
1995
Pell, J.A.Pell, J.A.Kimberlites in the Slave Province, Northwest Territories: a preliminaryreview.northwest Territories Open File, No. 1995-12, 20p.Northwest TerritoriesSlave Province, Geology, geochemistry
DS1996-1103
1996
Pell, J.A.Pell, J.A.Kimberlites in the Slave structural Province, northwest Territories CanadaThe Gangue, No. 51, January pp. 1, 3, 4.Northwest TerritoriesOverview, Genesis, setting, ages
DS1997-0896
1997
Pell, J.A.Pell, J.A.Kimberlites in the Slave Craton, Northwest Territories CanadaGeoscience Canada, Vol. 24, No. 2, pp. 77-90.Northwest TerritoriesOverview, History, Statistics, characteristics, Lac de Gras
DS1997-0897
1997
Pell, J.A.Pell, J.A., Stanley, M., Relf, C.Archean carbonatite bearing alkaline complexes, Slave structural northwest Territories.Geological Association of Canada (GAC) Abstracts, POSTER.Northwest TerritoriesCarbonatite, Slave Structural province
DS1998-1630
1998
Pell, J.A.Zhao, D., Essene, E.J., Zhang, Y., Pell, J.A.Mantle xenoliths from the Nikos kimberlites on Somerset Island and the Zulu kimberlites on Brodeur Peninsula.7th International Kimberlite Conference Abstract, pp. 998-1000.Northwest Territories, Somerset Island, Brodeur PeninsulaXenoliths, mineral chemistry, Deposit - Nikos, Zulu
DS2003-1059
2003
Pell, J.A.Pell, J.A., Ijewliw, O.J.Kimberlites, melnoites and look alikes in British Columbia, Canada8 Ikc Www.venuewest.com/8ikc/program.htm, Session 8, POSTER abstractBritish ColumbiaBlank
DS200412-1519
2003
Pell, J.A.Pell, J.A., Ijewliw, O.J.Kimberlites, melnoites and look alikes in British Columbia, Canada.8 IKC Program, Session 8, POSTER abstractCanada, British ColumbiaDiamond exploration
DS201312-0647
2013
Pell, J.A.Nichols, K.M.A., Stachel, T., Pell, J.A., Mate, D.J.Diamond sources beneath the Hall Peninsula, Baffin Island, Nunavut: preliminary assessment based on microdiamonds.Canada-Nunavut Geoscience Summary of Activities 2012, pp. 113-120.Canada, Nunavut, Baffin IslandDeposit - Chidliak
DS201807-1496
2018
Pell, J.A.Grutter, H.S., Pell, J.A., Fitzgerald, C.E.Use of a simplified Mahalanobis distance approach to constrain the dispersion and provenance of Cr-pyrope populations at the Chidliak kimberlite province, Nunavut, Canada.Mineralogy and Petrology, June 14, DOI:10.1007/ s0710-018 -0578-7, 12p.Canada, Nunavutdeposit - Chidliak

Abstract: Exploration for diamond-bearing kimberlites in the Chidliak project area by Peregrine Diamonds has generated a grid-like till sampling pattern across four discrete areas of interest totalling 402 km2 that is densely populated with research-grade compositional data for 10,743 mantle-derived Cr-pyrope garnets. The available dataset is well suited to statistical analysis, in part due to the relatively unbiased spatial coverage. Previous workers showed empirically that the TiO2 and Mn thermometry (Ti-TMn) attributes of Cr-pyrope populations at the Chidliak project may serve as source-specific “fingerprints”. In this work, we employ a simplified version of the multivariate Mahalanobis distance technique to formally examine the variability of, and differences between, Ti-TMn attributes of Cr-pyrope subpopulations recovered from a Laurentide-age glaciated terrain that also contains 30 known kimberlites within the four areas of interest. We show the simplified Mahalanobis distance approach enables accurate discrimination of Cr-pyrope subpopulations with subtly to distinctly different Ti-TMn attributes, and permits proper demarcation of their respective kimberlite source(s), specifically in areas with straightforward glacial histories. Redistribution and blending of Cr-pyrope subpopulations from known kimberlite sources is also observed, and typifies areas at Chidliak with complex late-glacial histories. Our results support <1 km horizontal scale subtle to obvious variability in the proportions of TiO2-rich and high-temperature (> 1100 °C) Cr-pyropes between closely spaced kimberlite source(s) and also between physically adjacent magma batches within single kimberlite pipes. The local scale variability is attributed to protokimberlite fluid or melt interacting with, and metasomatizing discrete conduits within, the ambient diamond-facies peridotitic mantle at times closely preceding eruption of kimberlite magma batches at Chidliak.
DS201508-0371
2015
Pell, R.Pell, R.Kovdor plans for expansion. International Mining, July p. 16, 18, 20Russia, Kola PeninsulaDeposit - Kovdor
DS201711-2535
2017
Pell, R.S.Wall, F., Rollat, A., Pell, R.S.Responsible sourcing for critical metals.Elements, Vol. 13, pp. 313-318.Globalresources, REE

Abstract: Most critical raw materials, such as the rare-earth elements (REEs), are starting products in long manufacturing supply chains. Unlike most consumers, geoscientists can become involved in responsible sourcing, including best environmental and social practices, because geology is related to environmental impact factors such as energy requirements, resource efficiency, radioactivity and the amount of rock mined. The energy and material inputs and the emissions and waste from mining and processing can be quantified, and studies for REEs show little difference between ‘hard rocks’, such as carbonatites, and easily leachable ion-adsorption clays. The reason is the similarity in the embodied energy in the chemicals used for leaching, dissolution and separation.
DS200912-0236
2009
Pell, S.Fumagalli, P., Zanchetta, S., Pell, S.Alkali in phlogopite and amphibole and their effects on phase relations in metasomatized peridotites: a high pressure study.Contributions to Mineralogy and Petrology, Vol. 158, pp. 723-737.MantleMetasomatism. subduction
DS200812-0877
2008
Pelleg, M.Pelleg, M.Head for Africa.IDI The Israeli Diamond Industry newsletter, Feb. 2p.AfricaNews item - DMC
DS2000-0793
2000
Pellegrini, R.Ranneli, G., Pellegrini, R., D'Offizi, S.Time dependence of negative bouyancy and the subduction of continental lithosphere.Journal of Geodynm., Vol. 30, No. 5, pp. 539-55.MantleSubduction
DS201412-0671
2014
Pelleter, A-A.Pelleter, A-A., Caroff, M., Cordier, C., Bachelery, P., Nehlig, P., Debeuf, D., Arnaud, N.Melilite bearing lavas as Mayotte ( France): an insight into the mantle source below the Comores.Lithos, in press available 57p.Europe, FranceMelilite
DS201810-2374
2018
Pelleter, A-A.Rosenthal, A., Yaxley, G.M., Crichton, W.A., Kovacs, I.J., Spandler, C., Hermann, J., Sandorne, J.K., Rose-Koga, E., Pelleter, A-A.Phase relations and melting of nominally 'dry' residual eclogites with variable CaO/Na2O from 3 to 5 Gpa and 1250 to 1500C; implications for refertilisation of upwelling heterogeneous mantle. Lithos, Vol. 314-315, pp. 506-519.Mantlemelting
DS1994-1360
1994
Pelletier, C.A.Pelletier, C.A.Environmental issues associated with diamond mine developmentThe Canadian Institute of Mining, Metallurgy and Petroleum (CIM) District 6, Oct. 11-15th. Vancouver, p.66 abstract onlyNorthwest TerritoriesEnvironment, Land management
DS1995-0466
1995
Pelletier, C.A.Dushnisky, K., Pelletier, C.A.Environmental risk assessment and international mineral developmentInternational Journal of Surface Mining, Reclamation and environ, Vol. 9, No. 1, pp. 19-22GlobalEnvironment, Mining development
DS1999-0549
1999
Pelletier, J.D.Pelletier, J.D.Statistical self similarity of magmatism and volcanismJournal of Geophysical Research, Vol. 104, No. 7, July 10, pp. 15425-38.GlobalMagmatism, volcanism.
DS1999-0550
1999
Pelletier, J.D.Pelletier, J.D.Paleointensity variations of Earth's magnetic field and their relationship with polarity reversals.Physical Earth and Planetary Interiors, Vol. 110, pp. 115-128.MantleGeophysics - magnetics
DS201502-0084
2015
Pelletier, M.Nadeau, O., Cayer, A., Pelletier, M., Stevenson, R., Jebrak, M.The Paleoproterozoic Montviel carbonatite hosted REE-Nb deposit, Abitibi, Canada: Geology, Mineralogy, Geochemistry and Genesis.Ore Geology Reviews, Vol. 67, pp. 314-335.Canada, QuebecCarbonatite
DS201808-1742
2018
Pelletier, M.Edahbi, M., Plante, B., Benzaazoua, M., Kormos, L., Pelletier, M.Rare earth elements ( La, Ce, Pr, Nd, and Sm) from a carbonatite deposit: mineralogical characterization and geochemical behavior. MontvielMinerals, Vol. 8, pp. 55-74.Canada, Quebeccarbonatite

Abstract: Geochemical characterization including mineralogical measurements and kinetic testing was completed on samples from the Montviel carbonatite deposit, located in Quebec (Canada). Three main lithological units representing both waste and ore grades were sampled from drill core. A rare earth element (REE) concentrate was produced through a combination of gravity and magnetic separation. All samples were characterized using different mineralogical techniques (i.e., quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN), X-ray diffraction (XRD), and scanning electron microscopy with X-ray microanalysis (SEM-EDS)) in order to quantify modal mineralogy, liberation, REE deportment and composition of REE-bearing phases. The REE concentrate was then submitted for kinetic testing (weathering cell) in order to investigate the REE leaching potential. The mineralogical results indicate that: (i) the main REE-bearing minerals in all samples are burbankite, kukharenkoite-Ce, monazite, and apatite; (ii) the samples are dominated by REE-free carbonates (i.e., calcite, ankerite, and siderite); and (iii) LREE is more abundant than HREE. Grades of REE minerals, sulfides and oxides are richer in the concentrate than in the host lithologies. The geochemical test results show that low concentrations of light REE are leached under kinetic testing conditions (8.8-139.6 ?g/L total light REE). These results are explained by a low reactivity of the REE-bearing carbonates in the kinetic testing conditions, low amounts of REE in solids, and by precipitation of secondary REE minerals.
DS1940-0035
1941
Pelletier, R.A.Pelletier, R.A.Diamond Deposits of Southern AfricaMining Engineering Journal of South Africa, Vol. 52, PT. 1, No. 2513.Southwest Africa, NamibiaReview Of Activities
DS1960-0486
1964
Pelletier, R.A.Pelletier, R.A.Mineral Resources of South Central AfricaWymberg: Rustica Press Pty. Ltd., 277P.South Africa, Central Africa, Zaire, Southwest Africa, NamibiaMineral Resources, Occurrences, Diamonds, Kimberley
DS1990-0225
1990
Pelley, C.W.Bostwick, C.J., Pelley, C.W.Computer aided interpretation of geotechnical dataThe Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Annual Meeting Paper preprint, No. 100, 19pGlobalComputer, Numerical modeling
DS1981-0134
1981
Pelsart resources nl.Dedman, R., Pelsart resources nl.Tr 7641h Cambridge Gulf Diamond Exploration Cambridge Gulf Sheet.West Australia Geological Survey Open File., No. GSWA 1204 ROLL 403 M 2791, 5P.Australia, Western AustraliaProspecting
DS1993-1504
1993
Pelthier, W.R.Solheim, L.P., Pelthier, W.R.Mantle phase Transitions and layered convectionCanadian Journal of Earth Sciences, Vol. 30, pp. 881-92.MantleConvection model
DS2000-0620
2000
Peltier, R.Marshall, S.J., Tarasov, L., Clarke, G., Peltier, R.Glaciological reconstruction of the Laurentide Ice Sheet: physical processes and modelling changes.Canadian Journal of Earth Sciences, Vol. 37, No.5, May pp.769-93.Ontario, CanadaGeomorphology
DS1991-0503
1991
Peltier, W.R.Forte, A.M., Peltier, W.R., Dziewonski, A.M.Inferences of mantle viscosity from tectonic plate velocitiesGeophysical Research Letters, Vol. 18, No. 9, September pp. 1747-1750GlobalMantle, Geophysics -plate tectonics
DS1991-1756
1991
Peltier, W.R.Tushingham, A.M., Lambert, A., Liard, J.O., Peltier, W.R.Secular gravity changes: measurements and predictions for selected CanadiansitesCanadian Journal of Earth Sciences, Vol. 28, No. 4, April pp. 557-560CanadaGeophysics -gravity, General
DS1992-1181
1992
Peltier, W.R.Peltier, W.R.Mantle convection and plate tectonics : towards a synthesisEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p. 272MantleModel, Tectonics
DS1993-1059
1993
Peltier, W.R.Mitrovica, J.X., Peltier, W.R.A new formation for inferring mantle viscosity based on estimates of Post glacial decay times: applications to RSL variations in northeast Hudson Bay.Geophysical Research Letters, Vol. 20, No. 20, October 22, pp. 2183-2187.OntarioMantle viscosity
DS1993-1060
1993
Peltier, W.R.Mitrovica, J.X., Peltier, W.R.A new formalism for inferring mantle viscosity based on estimates of Post glacial decay times: applications to RSL variations in northeast Hudson Bay.Geophysical Research Letters, Vol. 20, No. 20, October 22, pp. 2183-2186.OntarioMantle viscosity, Seal level changes
DS1993-1505
1993
Peltier, W.R.Solheim, L.P., Peltier, W.R.Mantle phase transitions and layered convectionCanadian Journal of Earth Sciences, Vol. 30, No. 5, May pp. 881-892GlobalLayered intrusions, Mantle, Numerical simulations
DS1995-1433
1995
Peltier, W.R.Pari, G., Peltier, W.R.The heat flow constraint on mantle tomography based convection models:geodynamically self consistent..Journal of Geophysical Research, Vol. 100, No.B7, July 10, pp. 12, 731-751.MantleTomography, Mantle viscosity
DS1996-1104
1996
Peltier, W.R.Peltier, W.R.Mantle viscosity and Ice age ice sheet topographyScience, Vol. 273, No. 5280, Sept. 6, pp. 1359-64.MantleGeomorphology -ice sheets
DS1996-1105
1996
Peltier, W.R.Peltier, W.R., Jiang, X.Glacial isostatic adjustment and Earth rotation: refined constraints on the viscosity of deepest mantle.Journal of Geophysics Research, Vol. 101, No. 2, Feb. 10, pp. 3269-90.MantleGeophysics -seismics, Geomorphology -glacial isostasy
DS1998-1120
1998
Peltier, W.R.Pari, G., Peltier, W.R.Global surface heat flux anomalies from seismic tomography based models of mantle flow: convection....Journal of Geophysical Research, Vol. 103, No. B10, Oct. 10, pp. 23743-80.MantleGeophysics - seismics, Flow
DS1998-1148
1998
Peltier, W.R.Peltier, W.R.Mantle mixing and the stability of the tectosphereGeological Society of America (GSA) Annual Meeting, abstract. only, p.A208.OntarioConvection, Hudson Bay gravity anomaly
DS2002-0233
2002
Peltier, W.R.Butler, S.L., Peltier, W.R.Thermal evolution of Earth: models with time dependent layering of mantle convection which satisfy the Urey ratio constraint.Journal of Geophysical Research, June 11, 10.1029/2000JB00018MantleGeophysics - geothermometry
DS2002-0234
2002
Peltier, W.R.Butler, S.L., Peltier, W.R.Thermal evolution of Earth: models with time depenedent layering of mantle convection which satisfy the Urey ratio constraint.Journal of Geophysical Research, Vol. 107, No. 6, ESE 3 DOI 10.1029/2001JB000018MantleGeothermometry
DS200412-1520
2004
Peltier, W.R.Peltier, W.R.Global glacial isostasy and the surface of the ice age Earth: the ICE=5G(VM2) model and GRACE.Annual Review of Earth and Planetary Sciences, Vol. 32, May pp. 111-149.GlobalOverview - climate system evolution, ice load, gravity
DS200512-0128
2005
Peltier, W.R.Butler, S.L., Peltier, W.R., Costin, S.O.Numerical models of the Earth's thermal history: effects of inner-core solidification and core potassium.Physics of the Earth and Planetary Interiors, Vol. 152, 1-2. Sept. 15, pp. 22-42.MantlePotassium, geothermometry, core history
DS200812-0878
2007
Peltier, W.R.Peltier, W.R.Mantle dynamics and the 'D' layer: impacts of the post perovskite phase.AGU American Geophysical Union Monograph, No. 174, pp. 217-228.MantleTectonics
DS201012-0685
2010
Peltier, W.R.Shahnas, D., Peltier, W.R.Layered convection and the impacts of the perovskite - postperovskite phase transition on mantle dynamics under isochemical conditions.Journal of Geophysical Research, Vol. 115, B 11, B11408.MantlePerovskite
DS200412-1111
2004
Peltonen, B.S.Lehtonen, M.L., O'Brien, H.E., Peltonen, B.S., Johanson, B.S., Pakkanen, L.K.Layered mantle at the Karelian Craton margin: P T of mantle xenocrysts and xenoliths from the Kaavi Kuopio kimberlites, Finland.Lithos, Vol. 77, 1-4, Sept. pp. 593-608.Europe, FinlandLithosphere, thermometry
DS1995-1473
1995
Peltonen, P.Peltonen, P.Crystallization and reequilibrium of zoned chromite in ultramafic cumulates Vammala nickel-belt, southwest FinlandCanadian Mineralogist, Vol. 33, No. 3, June pp. 521-536FinlandMineralogy, layered intrusion, nickel, Deposit -Vammala
DS1995-1474
1995
Peltonen, P.Peltonen, P.Magma country rock interaction and the genesis of nickel-copper deposits in the Vammala nickel belt, southwest FinlandMineralogy and Petrology, Vol. 52, No. 1-2, pp. 1-24FinlandNickel, Deposit -Vammala
DS1995-1475
1995
Peltonen, P.Peltonen, P.Petrogenesis of ultramafic rocks in the Vammala nickel belt: Implications for crustal evolutionLithos, Vol. 34, No. 4, February pp. 253-274FinlandNickel, Proterozoic terrane -Svecofennian
DS1995-1476
1995
Peltonen, P.Peltonen, P.Petrogenesis of ultramafics Vammala nickel belt: implications for crustal evolution early Proterozoic.Lithos, Vol. 34, pp. 253-274FinlandSvecofennian arc terrane, Deposit -Vammala
DS1998-0815
1998
Peltonen, P.Kukkonen, I.T., Peltonen, P.Geotherm and a rheological profile for the central Fennoscandianlithosphere.7th International Kimberlite Conference Abstract, pp. 478-9.Finland, KolaGeothermometry, Mantle xenoliths
DS1998-1149
1998
Peltonen, P.Peltonen, P.Silicification of garnet peridotite xenoliths from the Lahtojoki kimberlitepipe, eastern FIn land #17th. Kimberlite Conference abstract, pp. 676-7.FinlandMineral chemistry, Deposit - Lahtojoki
DS1998-1150
1998
Peltonen, P.Peltonen, P., Huhma, H., Tyni, ShimizuGarnet peridotite xenoliths from kimberlites of Finland: nature of the lithospheric mantle at Archean7th. Kimberlite Conference abstract, pp. 678-80.FinlandCraton, Paleoproterozoic mobile belt
DS1998-1593
1998
Peltonen, P.Woodland, A.B., Peltonen, P.Ferric/ferrous iron contents of garnet and clinopyroexne and calculated oxygen fugacities...7th International Kimberlite Conference Abstract, pp. 963-4.Finland, easternPeridotite xenoliths
DS1999-0381
1999
Peltonen, P.Kukkonen, I.T., Peltonen, P.Xenolith controlled geotherm for the central Fennoscandian shield:implications for lithosphere -Tectonophysics, Vol. 304, No. 4, Apr. 30, pp. 301-16.Scandinavia, Finland, Sweden, Norway, Baltic StatesAsthenosphere, Geothermometry - xenoliths
DS1999-0551
1999
Peltonen, P.Peltonen, P.Silicification of garnet peridotite xenoliths from the Lahtojoki kimberlite pipe, FIn land #27th International Kimberlite Conference Nixon, Vol. 2, pp. 659-63.FinlandMineral chemistry, Deposit - Lahtojoki
DS1999-0552
1999
Peltonen, P.Peltonen, P., Huhma, H., Tyni, M., Shimizu, N.Garnet peridotite xenoliths from kimberlites of Finland: nature of the continental mantle at Archean...7th International Kimberlite Conference Nixon, Vol. 2, pp. 664-76.Finland, Fennoscandia, Eastern FinlandTransition - Archean Craton - Proterozoic mobile belt, Petrography, analyses
DS1999-0807
1999
Peltonen, P.Woodland, A.B., Peltonen, P.Ferric iron contents of garnet and clinopyroxene and estimated oxygen fugacities of peridotite xenoliths ..7th International Kimberlite Conference Nixon, Vol. 2, pp. 904-11.Finland, EasternKimberlite province, mineral chemistry, Deposit - Kaavi cluster
DS2002-0402
2002
Peltonen, P.Downes, H., Peltonen, P., Manttari, I., Sharkov, E.V.Proterozoic zircon ages from lower crust granulite xenoliths, Kola Peninsula, Russia: evidence for crustal growth and reworking.Journal of the Geological Society of London, Vol. 159, 2, pp. 485-488.Russia, Kola PeninsulaBlank
DS2002-1239
2002
Peltonen, P.Peltonen, P., Kinnunen, K.A., Hihma, H.Petrology of two Diamondiferous eclogite xenoliths from the Lahtojoki kimberlite pipe, eastern Finland.Lithos, Vol. 63, pp. 151-164.FinlandPetrology, therombarometry, deformation, Deposit - Lahtojoki
DS2002-1240
2002
Peltonen, P.Peltonen, P., Manttari, I.An ion microprobe U Th Pb study of zircon xenocrysts from the Lahtojoki kimberlite pipe eastern Finland.Geological Society of Finland Bulletin, Vol. 73, 1/2, pp. 47-58.FinlandGeochronology, Deposit - Lahtojoki
DS2003-0756
2003
Peltonen, P.Kukkonen, I.T., Kinnunen, K.A., Peltonen, P.Mantle xenoliths and thick lithosphere in the Fennoscandian ShieldPhysics and Chemistry of the Earth, parts A,B,C, Vol. 28, 9-11, pp. 349-60.FennoscandiaBlank
DS2003-0791
2003
Peltonen, P.Lehtonen, M.L., O'Brien, H.E., Peltonen, P., Johanson, B.S., Pakkanen, L.K.Layered mantle at the edge of the Karelian craton: P-T of mantle xenocrysts and8 Ikc Www.venuewest.com/8ikc/program.htm, Session 6, POSTER abstractFinlandBlank
DS2003-1060
2003
Peltonen, P.Peltonen, P.Platinum group element geochemistry of eastern FIn land kimberlites and their mantle8ikc, Www.venuewest.com/8ikc/program.htm, Session 4, POSTER abstractFinlandMantle geochemistry
DS2003-1061
2003
Peltonen, P.Peltonen, P., Manttari, I., Huhma, H., Kontinen, A.Archean zircons from the mantle: the Jormua ophiolite revisitedGeology, Vol. 31, 7, July, pp. 645-8.EuropeGeochronology
DS200412-0478
2002
Peltonen, P.Downes, H., Peltonen, P., Manttari, I., Sharkov, E.V.Proterozoic zircon ages from lower crust granulite xenoliths, Kola Peninsula, Russia: evidence for crustal growth and reworking.Journal of the Geological Society, Vol. 159, 2, pp. 485-488.Russia, Kola PeninsulaGeochronology
DS200412-1062
2003
Peltonen, P.Kukkonen, I.T., Kinnunen, K.A., Peltonen, P.Mantle xenoliths and thick lithosphere in the Fennoscandian Shield.Physics and Chemistry of the Earth Parts A,B.C, Vol. 28, 9-11, pp. 349-60.Europe, FennoscandiaXenoliths
DS200412-1112
2003
Peltonen, P.Lehtonen, M.L., O'Brien, H.E., Peltonen, P., Johanson, B.S., Pakkanen, L.K.Layered mantle at the edge of the Karelian craton: P-T of mantle xenocrysts and xenoliths from eastern FIn land kimberlites.8 IKC Program, Session 6, POSTER abstractEurope, FinlandMantle petrology
DS200412-1521
2003
Peltonen, P.Peltonen, P., Manttari, I., Huhma, H., Kontinen, A.Archean zircons from the mantle: the Jormua ophiolite revisited.Geology, Vol. 31, 7, July, pp. 645-8.EuropeGeochronology
DS200512-0796
2005
Peltonen, P.O'Brien, H.E., Peltonen, P., Vartiainen, H.Kimberlites, carbonatites and alkaline rocks.Elsevier: Lehtinen, M., Nurmi, P.A., Rama, O.T. eds. Precambrian geology of Finland: key to the evolution, pp.Europe, Finland, FennoscandiaOverview
DS200612-0850
2005
Peltonen, P.Maier, W.D., Peltonen, P., Juvonen, R., Pienaar, C.Platinum group elements in peridotite xenoliths and kimberlite from the Premier kimberlite pipe, South Africa.South African Journal of Geology, Vol. 108, pp. 413-428.Africa, South AfricaDeposit - Premier, xenolith mineralogy
DS200612-1068
2006
Peltonen, P.Peltonen, P., Brugmann, G.Origin of layered continental mantle ( Karelian craton, Finland): geochemical and Re-Os isotope constraints.Lithos, Vol. 89, 3-4, July pp. 405-423.Europe, Finland, FennoscandiaMetasomatism, geochronology, peridotite
DS200612-1069
2006
Peltonen, P.Peltonen, P., Manttari, I., Huhma, H., Whitehouse, M.J.Multi stage origin of the lower crust of the Karelian craton from 3.5 to 1.7 Ga based on isotopic ages of kimberlite derived mafic granulite xenoliths.Precambrian Research, Vol. 147, 1-2, June 10, pp. 107-123.Europe, FinlandGeochronology, kimberlite, mantle plume, craton
DS200712-0669
2007
Peltonen, P.Maier, W.D., McDonald, I., Peltonen, P., Barnes, S-J., Gurney, J., Hatton, C.Platinum group elements in mantle xenoliths from the Kaapvaal Craton.Plates, Plumes, and Paradigms, 1p. abstract p. A614.Africa, South Africa, Botswana, LesothoKimberley, Jagersfontein, Lethlakane, Finsch, Venetia
DS200812-0614
2008
Peltonen, P.Kukkonen, I.T., Kuusisto, M., Lehonen, M., Peltonen, P.Delamination of eclogitized lower crust: control on the crust-mantle boundary in the central Fennoscandian shield.Tectonophysics, Vol. 457, pp. 111-127.Europe, FinlandKimberlites discussed
DS200812-0810
2008
Peltonen, P.O'Brien, H.E., Legtonen, M.L., Grimmer, S.G., McNulty, K., Peltonen, P., Kontinen, A.Kimberlites in Finland. Geology of kimberlites, carbonatites and alkaline rocks. Seitapera kimberlite and Jormua ophiolite complex.9th. IKC Field Trip Guidebook, CD 58p.Europe, FinlandGuidebook - kimberlites, carbonatites
DS200912-0432
2009
Peltonen, P.Lehtonen, M., O'Brien, H., Peltonen, P., Kukkonen, I., Ustinov, V., Verzhak, V.Mantle xenocrysts from the Arkangelskaya kimberlite (Lomonosov); constraints on the composition and thermal state of the Diamondiferous lithospheric mantle.Lithos, in press availableRussia, Kola Peninsula, ArchangelDeposit - Lomonosov
DS200912-0870
2009
Peltonen, P.Zozulya, D.R., Mitrofanov, F.P., Peltonen, P., O'Brien, H., Lehtonen, M., Kalachev, V.Yu.Lithospheric mantle structure and diamond prospects in the Kola region: chemical and thermobarometric analyses of kimberlite pyrope.Doklady Earth Sciences, Vol. 427, 5, pp. 746-750.Russia, Kola PeninsulaGeothermometry
DS200912-0871
2008
Peltonen, P.Zozulya, D.R., Peltonen, P., O'Brien, H.Pyrope and Cr-diopside as indicators of mantle structure and diamond depth facies in the Kola region.Geology of Ore Deposits, Vol. 50, 7, pp. 524-534.Russia, Kola Peninsula, ArchangelTectonics
DS200912-0872
2009
Peltonen, P.Zozulya, D.R., Peltonen, P., O'Brien, H., Lehtonen, M.Lithospheric roots and asthenospheric upwarps of the NE Baltic Shield: spatial controls for kimberlitic and alkaline magmatism.alkaline09.narod.ru ENGLISH, May 10, 2p. abstractEurope, Baltic Shield, Kola PeninsulaMagmatism
DS200912-0873
2009
Peltonen, P.Zozulya, D.R., Peltonen, P., O'Brien, H., Lehtonen, M.Mantle depth facies of high pressure pyroxene in the Kola region.Doklady Earth Sciences, Vol. 424, 1, pp. 52-56.Russia, Kola PeninsulaMineralogy
DS201012-0897
2009
Peltonen, P.Zozulya, D.R., O'Brien, H., Peltonen, P., Lehtonen, M.Thermobarometry of mantle derived garnets and pyroxenes of Kola region ( NW Russia): lithosphere composition, thermal regime and diamond prospectivity.Bulletin of the Geological Society of Finland, Vol. 81, pp. 143-158.Russia, Kola PeninsulaGeothermometry
DS201012-0898
2009
Peltonen, P.Zozulya, D.R., O'Brien, H., Peltonen, P., Lehtonen, M.Thermobarometry of mantle derived garnets and pyroxenes of Kola region ( NW Russia): lithosphere composition, thermal regime and diamond prospectivity.Bulletin of the Geological Society of Finland, Vol. 81, pp. 143-158.Russia, Kola PeninsulaGeothermometry
DS201212-0430
2012
Peltonen, P.Maier, W.D., Peltonen, P., McDonald, I., Barnes, S.J., Barnes, S-J., Hatton, C., Viljoen, F.The concentration of platinum group elements and gold in southern African and Karelian kimberlite hosted mantle xenoliths: implications for the noble metal content of the Earth's mantle.Chemical Geology, Vol. 302-303, pp. 119-135.Africa, southern AfricaKimberlite - PGM
DS201709-2029
2017
Peltonen, P.Maier, W.D., O'Brien, H., Peltonen, P., Barnes, S-J.Platinum group element contents of Karelian kimberlites: implications for the PGE budget of the sub-continental lithospheric mantle.Geochimica et Cosmochimica Acta, in press available, 14p.Europe, Finlanddeposit - Kaavi

Abstract: We present high-precision isotope dilution data for Os, Ir, Ru, Pt, Pd and Re in Group I and Group II kimberlites from the Karelian craton, as well as 2 samples of the Premier Group I kimberlite pipe from the Kaapvaal craton. The samples have, on average, 1.38 ppb Pt and 1.33 ppb Pd, with Pt/Pd around unity. These PGE levels are markedly lower, by as much as 80%, than those reported previously for kimberlites from South Africa, Brazil and India, but overlap with PGE results reported recently from Canadian kimberlites. Primitive-mantle-normalised chalcophile element patterns are relatively flat from Os to Pt, but Cu, Ni and, somewhat less so, Au are enriched relative to the PGE (e.g., Cu/Pd > 25.000). Pd/Ir ratios are 3,6 on average, lower than in most other mantle melts. The PGE systematics can be largely explained by two components, (i) harzburgite/lherzolite detritus of the SCLM with relatively high IPGE (Os-Ir-Ru)/PPGE (Rh-Pt-Pd) ratios, and (ii) a melt component that has high PPGE/IPGE ratios. By using the concentrations of iridium in the kimberlites as a proxy for the proportion of mantle detritus in the magma, we estimate that the analysed kimberlites contain 3–27% entrained and partially dissolved detritus from the sub-continental lithospheric mantle, consistent with previous estimates of kimberlites elsewhere (Tappe S. et al., 2016, Chem. Geol. http://dx.doi.org/10.1016/j.chemgeo.2016.08.019). The other major component in the samples is melt, modelled to contain an average of 0.85 ppb Pt and 1.09 ppb Pd. Assuming that Group II kimberlites are derived from relatively metasomatised SCLM, our data suggest that the metasomatised Karelian SCLM is relatively poor in Pt and Pd. If our data are representative of other Group II kimberlites elsewhere, this result could imply that the PGE enrichment in certain continental large igneous provinces, including Bushveld, is not derived from melting of metasomatised SCLM.
DS201710-2244
2017
Peltonen, P.Maier, W.D., O'Brien, H., Peltonen, P., Barnes, S-J.Platinum group element contents of Karelian kimberlites: implications for the PGE budget of the sub-continental lithospheric mantle.Geochimica et Cosmochimica Acta, Vol. 216, pp. 358-371.Europe, Finlanddeposit - Karelian

Abstract: We present high-precision isotope dilution data for Os, Ir, Ru, Pt, Pd and Re in Group I and Group II kimberlites from the Karelian craton, as well as 2 samples of the Premier Group I kimberlite pipe from the Kaapvaal craton. The samples have, on average, 1.38 ppb Pt and 1.33 ppb Pd, with Pt/Pd around unity. These PGE levels are markedly lower, by as much as 80%, than those reported previously for kimberlites from South Africa, Brazil and India, but overlap with PGE results reported recently from Canadian kimberlites. Primitive-mantle-normalised chalcophile element patterns are relatively flat from Os to Pt, but Cu, Ni and, somewhat less so, Au are enriched relative to the PGE (e.g., Cu/Pd > 25.000). Pd/Ir ratios are 3,6 on average, lower than in most other mantle melts. The PGE systematics can be largely explained by two components, (i) harzburgite/lherzolite detritus of the SCLM with relatively high IPGE (Os-Ir-Ru)/PPGE (Rh-Pt-Pd) ratios, and (ii) a melt component that has high PPGE/IPGE ratios. By using the concentrations of iridium in the kimberlites as a proxy for the proportion of mantle detritus in the magma, we estimate that the analysed kimberlites contain 3-27% entrained and partially dissolved detritus from the sub-continental lithospheric mantle, consistent with previous estimates of kimberlites elsewhere (Tappe S. et al., 2016, Chem. Geol. http://dx.doi.org/10.1016/j.chemgeo.2016.08.019). The other major component in the samples is melt, modelled to contain an average of 0.85 ppb Pt and 1.09 ppb Pd. Assuming that Group II kimberlites are derived from relatively metasomatised SCLM, our data suggest that the metasomatised Karelian SCLM is relatively poor in Pt and Pd. If our data are representative of other Group II kimberlites elsewhere, this result could imply that the PGE enrichment in certain continental large igneous provinces, including Bushveld, is not derived from melting of metasomatised SCLM.
DS201805-0970
2001
Peltonen, P.Peltonen, P., Manttari, I.An ion microprobe U Th Pb study of zircon xenocrysts from the Lahtojoki kimberlite pipe, eastern Finland. NOTE Date of publ.Bulletin of the Geological Survey of Finland, Vol. 73, 1-2, pp. 47-58.Europe, Finlanddeposit - Lahtojoki

Abstract: Eleven relatively large (diameter 1-2 mm) zircon grains extracted from the Lahtojoki kimberlite pipe (Eastern Finland Kimberlite Province) have been analysed by the ion microprobe NORDSIM for their U- and Pb- isotopic composition. The 207Pb/206Pb ages fall into two concordant age groups: 2.7 Ga and 1.8 Ga. Discordant ages between these two groups are believed to result from partial resetting of Archaean grains in the 1.8 Ga thermal event. Since other datingmethods imply that kimberlites emplaced c. 0.6 Ga ago it is clear that the analysed zircons are xenocrysts inherited from older sources and do not provide the age of the kimberlite magmatism. Their unusual size and morphology, together with very low U- and Pb-concentrations, suggest, however, that these zircon grains are not derived from typical Archaean gneisses. More likely, they originate from lower crustal mafic pegmatites and from hydrous coarse-grained veins within the uppermost lithospheric mantle. The predominance of 1.8 Ga old xenocrystic grains, together with the recovery of mafic granulite xenoliths of similar age in the kimberlites (Hölttä et al. 2000), emphasises the importance of post-collisional lower crustal growth and reworking in central Fennoscandia.
DS200912-0869
2009
Peltonen, S.A.P.A.Zozulya, D.A.R.A., Peltonen, S.A.P.A., O'Brien, H.A., Lehtonen, M.A.Kimberlite depth facies of high pressure pyroxene in the Kola region.Doklady Earth Sciences, Vol. 425, 2, pp. 350-352.Russia, Kola PeninsulaUHP
DS1997-0898
1997
Peltonnienmi, M.Peltonnienmi, M.Review article: geophysics and CD-ROM technologyFirst Break, Vol. 15, No. 5, May pp. 139-146GlobalGeophysics, Review - CD ROM technology
DS1980-0279
1980
Pelzer, H.Pelzer, H.Die Diamant SpeurderCape Town: Tafelberg Publishing, 88P.Namibia, Southwest AfricaKimberlite, Kimberley, Janlib, Fiction
DS201506-0289
2015
Pemberton, A.Nowacki, A., Kendall, J-M., Wookey, J., Pemberton, A.Mid mantle anisotropy in subduction zones and deep water transport.Geochemistry, Geophysics, Geosystems: G3, Vol 16, 3, pp. 764-784.MantleSubduction
DS201912-2821
2019
Pena-Alvarez, M.Sanatmaria-Perez, D., Ruiz-Fuertes, J., Pena-Alvarez, M., Chulia-Jordan, R., Marquerno, T., Zimmer, D., Guterrez-Cano, V., Macleod, S., Gregoryanz, E., Popescue, C., Rodriguez-Herandez, P., Munoz, A.Post-tilleyite, a dense calcium silicate carbonate phase.Nature Scientific Reports, Vol. 9, 11p. PdfMantletilleyite

Abstract: Calcium carbonate is a relevant constituent of the Earth’s crust that is transferred into the deep Earth through the subduction process. Its chemical interaction with calcium-rich silicates at high temperatures give rise to the formation of mixed silicate-carbonate minerals, but the structural behavior of these phases under compression is not known. Here we report the existence of a dense polymorph of Ca5(Si2O7)(CO3)2 tilleyite above 8 GPa. We have structurally characterized the two phases at high pressures and temperatures, determined their equations of state and analyzed the evolution of the polyhedral units under compression. This has been possible thanks to the agreement between our powder and single-crystal XRD experiments, Raman spectroscopy measurements and ab-initio simulations. The presence of multiple cation sites, with variable volume and coordination number (6-9) and different polyhedral compressibilities, together with the observation of significant amounts of alumina in compositions of some natural tilleyite assemblages, suggests that post-tilleyite structure has the potential to accommodate cations with different sizes and valencies.
DS201811-2555
2019
Penaye, J.Bouyo, M.H., Penaye, J., Mount, H., Toleu, S.F.Eclogite facies metabasites from the Paleoproterozoic Nyong Group, SW Cameroon: mineralogical evidence and implications for a high pressure metamorphism related to a subduction zone at the NW margin of the Archean Congo craton.Journal of African Earth Sciences, Vol. 149, pp. 215-234.Africa, Cameroonsubduction

Abstract: High- to ultrahigh-pressure metamorphic assemblages consisting of garnet-omphacitic clinopyroxene bearing mafic rocks have been identified within the Paleoproterozoic Nyong Group in SW Cameroon, at the northwestern margin of the Archean Congo craton. These rocks were investigated in detail and for the first time evidence for eclogite facies metamorphism at ca 25?kbar and 850?°C is provided. A clockwise P-T path with nearly isothermal decompression (ITD) is deduced from mineral zoning and textural relationships characterized by mineral recrystallization and multi-layered coronitic overgrowths of plagioclase and clinopyroxene surrounding garnet porphyroblasts. These P-T conditions imply a burial depth greater than 90?km, at lower geothermal gradient of ca 10?°C/km. The geochemical signature of ten representative rock samples show that two groups of eclogite facies rocks genetically originate from mostly basaltic and basaltic andesite compositions, with a characteristic upper mantle-derived tholeiitic trend. Moreover, their chondrite and MORB normalized REE and trace element concentrations are characterized by nearly flat REE patterns with very little to no Eu anomaly, (La/Sm)N???1 and Zr/Nb???10, as well as a gradual depletion from LREE to HREE with also very little to no Eu anomaly, but (La/Sm)N < 1, Zr/Nb > 10 and negative anomalies in Th, K, Nb, Ta, Sr, Zr and Ti consistent with mid-ocean ridge basalt (MORB) contaminated by a subduction component or by a crustal component. Previous available geochronological data coupled with our new petrological, mineralogical and geochemical findings clearly indicate that the eclogite facies metabasites from the Eburnean Nyong Group between 2100 and 2000 Ma represent one of the oldest subducted oceanic slab or trace of a suture zone so far recorded within the West Central African Fold Belt (WCAFB). The geodynamic implications of these eclogites suggest a subduction-related process followed by a rapid exhumation of their protoliths, therefore, providing critical information corroborating that plate tectonic processes operated during the Paleoproterozoic.
DS200812-0706
2008
Pendey, G.P.Mali, B.M., Pendey, G.P., Candrakala, K., Reddy, P.R.Imprints of a Proterozoic tectonothermal anomaly below the 1.1 Ga kimberlitic province of southwest Cuddapah Basin, Dharwar craton, southern India.Geophysical Journal International, Vol. 172, 1, pp. 422-438.IndiaGeothermometry
DS1989-0622
1989
Pendlebury, K.Henderson, C.M.R., Pendlebury, K., Foland, K.A.Mineralogy and petrology of the Red Hill alkaline igneous complex, NewHampshire, United States (US)Journal of Petrology, Vol. 30, No. 3, June pp. 627-666GlobalAlkaline rocks, Red Hill complex
DS1998-1151
1998
Pendock, N.Pendock, N.Breaking the Nyquist Barrier: super resolution magnetic imaging from gradient data.7th. Kimberlite Conference abstract, pp. 681-3.South AfricaGeophysics - magnetic gradiometer
DS201708-1733
2017
Pendock, N.Pendock, N.Mapping heat flow from a time series of satellite temperature images as a regional exploration tool for kimberlites.11th. International Kimberlite Conference, OralTechnologyGeothermometry
DS201807-1521
2018
Pendock, N.Pendock, N.Regional diamond exploration under cover. ASTER bands, LWIR indicator mineralsSAIMM Diamonds - source to use 2018 Conference 'thriving in changing times'. June 11-13., pp. 103-112.Africa, Botswanadeposit - Orapa, Damtshaa, BK09, BK12,AK01
DS201807-1522
2016
Pendock, N.Pendock, N.Hot stones: mapping igneous kimberlites under Kalahari cover using LWIR imagery.www.grsg.org.uk/wp-content/uploads/2017/01/Day2/Neil%20Pendock%20RSA.pdf, 29 ppts. AvailableAfrica, Botswanageospectral
DS201808-1776
2018
Pendock, N.Pendock, N.Regional diamond exploration under cover. PresentationSAIMM Diamonds - source to use 2018 Conference 'thriving in changing times'. June 11-13., 26 ppts.Africa, Botswanageophysics
DS1998-1639
1998
Pendock, N.E.Zichella, V., De Gasperis, A.A., Pendock, N.E.Mineral mapping with hyper spectral data: a case study over the Moses Rock Dyke and Mule Ear Diatreme, Utah.7th International Kimberlite Conference Abstract, pp. 1007-8.Utah, United States, Colorado PlateauRemote sensing, Deposit - Moses Rock, Mule Ear
DS201112-1123
2011
Peng, M.Wu, Y., Gao, S., Liu, X., Wang, J., Peng, M., Gong, H., Yuan, H.Two stage exhumation of the ultrahigh pressure metamorphic rocks from the Western Dabie Orogen, central China.Journal of Geology, Vol. 119, pp. 15-32.ChinaUHP
DS201112-1124
2011
peng, M.Wu, Y., Gao, S., liu, X., Wang, J., peng, M., Gong, H., Yuan, H.Two stage exhumation of ultrahigh pressure metamorphic rocks from the western Dabie orogen, Central China.Journal of Geology, Vol. 119, 1, Jan. pp. 15-31.ChinaUHP
DS201112-1125
2011
Peng, M.Wu, Y., Gao, S., Liu, X., Wang, J., Peng, M., Gong, H., Yuan, H.Two stage exhumation of ultrahigh pressure metamorphic rocks from the western Dabie Orogen, central China.Journal of Petrology, Vol. 119, no. 1, pp. 15-31.ChinaUHP
DS200612-1580
2006
Peng, M-S.Yuan, J.C.C., Peng, M-S., Meng, Y-f.Investigation by synchrotron X ray diffraction topography of the crystal structure defects in colored diamonds ( natural, synthetic and treated).GIA Gemological Research Conference abstract volume, Held August 26-27, p. 24. 1/2p.TechnologyX-ray diffraction
DS201312-0992
2013
Peng, M-s.Yang, Z-j., Liang, R., Zeng, X-q., Ge, T-y., Al Qun, Zhenh, Y-l., Peng, M-s.Study on the micro-infrared spectra and origin of polycrystalline diamonds from Mengyin kimberlite pipes.Spectroscopy and Spectral Analysis, Vol. 32, 8, pp. 1512-1518.ChinaDeposit - Mengyin
DS2003-1542
2003
Peng, P.Zhai, M., Guo, J., Li, Y., Peng, P., Shi, X.Two linear granite belts in the central western North Chin a Craton and their implicationPrecambrian Research, Vol. 127, 1-2, Nov. pp.267-283.ChinaTectonics
DS200412-2200
2003
Peng, P.Zhai, M., Guo, J., Li, Y., Peng, P., Shi, X.Two linear granite belts in the central western North Chin a Craton and their implication for Late Neoarchean Paleoproterozoic coPrecambrian Research, Vol. 127, 1-2, Nov. pp.267-283.ChinaTectonics
DS200512-0836
2005
Peng, P.Peng, P., Zhai, M., Zhang, H., Guo, J.Geochronological constraints on the Paleoproterozoic evolution of the North Chin a Craton: SHRIMP zircon ages of different types of mafic dikes.International Geology Review, Vol. 47, 5, May, pp. 492-508.ChinaGeochronology
DS200712-0826
2007
Peng, P.Peng, P., Zhai, M-G., Guo, J-H, Kusky, T.,Ping, T.Nature of mantle source contributions and crystal differentiation in the petrogenesis of the 1.78 Ga mafic dykes in the central North Chin a Craton.Gondwana Research, Vol. 12, 1-2, August pp. 29-46.ChinaDyke chemistry
DS200712-0827
2007
Peng, P.Peng, P., Zhai, M-G., Guo, J-H, Kusky, T.,Ping, T.Nature of mantle source contributions and crystal differentiation in the petrogenesis of the 1.78 Ga mafic dykes in the central North Chin a Craton.Gondwana Research, Vol. 12, 1-2, August pp. 29-46.ChinaDyke chemistry
DS200812-0879
2008
Peng, P.Peng, P., Zhai, M., Ernst, R.E., Guo, J., Liu, F., Hu, B.A 1.78 Ga large igneous province in the North Chin a Craton: the Xionger volcanic province and the North Chin a dyke swarm.Lithos, Vol. 101, 3-4, pp. 260-280.ChinaGeochemistry
DS201703-0428
2015
Peng, P.Peng, P.Precambrian mafic dyke swarms in the North Chin a craton and their geological implications.Science China Earth Sciences, Vol. 58, 5, pp. 649-675.ChinaCraton, North China

Abstract: A map of major Precambrian mafic dyke swarms and related units in the North China Craton is compiled, and the features and geological implications of these swarms are demonstrated. The Archean dyke swarms are available to portray the early crustal growth and cratonization. The middle Paleoproterozoic (2200-1850 Ma) swarms and related magmatic series could constrain the tectonic evolution: They approve that the craton was amalgamated by two sub-cratons. The late Paleoproterozoic (1800-1600 Ma), Mesoproterozoic (1400-1200 Ma) and Neoproterozoic (1000-800 Ma) series swarms are important in paleogeographic reconstruction: they indicate that North China might have connected with some of the North European and North American cratons during Proterozoic. Dyke swarms are not only geological timescales and tectonic markers but also evolution indicators of lithospheric mantle: they imply a rejuvenation of the sub-continental lithospheric mantle of North China at 1780-1730 Ma. These swarms occurred with several rifts, including the Hengling (2200-1970 Ma), Xuwujia (1970-1880 Ma), Xiong’er (1800-1600 Ma), Yan-Liao (1730-1200 Ma), and Xu-Huai (1000-800 Ma). Among them, the Xuwujia rift was possibly continental arc associated; whereas the others were intra-continental. In addition, the Xiong’er and Xu-Huai rifts were possibly triple junctions along the present southern and southeastern margins of the Craton, respectively. Different tectonic settings of these rifts and dyke swarms would result in diversified series of ore deposits.
DS202101-0040
2021
Peng, P.Wang, C., Mitchell, Ross.N., Murphy, J.B., Peng, P., Spencer, C.J.The role of megacontinents in the supercontinent cycle.Geology, in press availabe 5p. PdfMantlePangea

Abstract: Supercontinent Pangea was preceded by the formation of Gondwana, a “megacontinent” about half the size of Pangea. There is much debate, however, over what role the assembly of the precursor megacontinent played in the Pangean supercontinent cycle. Here we demonstrate that the past three cycles of supercontinent amalgamation were each preceded by ~200 m.y. by the assembly of a megacontinent akin to Gondwana, and that the building of a megacontinent is a geodynamically important precursor to supercontinent amalgamation. The recent assembly of Eurasia is considered as a fourth megacontinent associated with future supercontinent Amasia. We use constraints from seismology of the deep mantle for Eurasia and paleogeography for Gondwana to develop a geodynamic model for megacontinent assembly and subsequent supercontinent amalgamation. As a supercontinent breaks up, a megacontinent assembles along the subduction girdle that encircled it, at a specific location where the downwelling is most intense. The megacontinent then migrates along the girdle where it collides with other continents to form a supercontinent. The geometry of this model is consistent with the kinematic transitions from Rodinia to Gondwana to Pangea.
DS200512-1168
2005
Peng, T.Wang, Y., Fan, W., Peng, T., Zhang, H., Gou, F.Nature of the Mesozoic lithospheric mantle and tectonic decoupling beneath the Dabie Orogen, central China. Evidence from 40Ar 39Ar geochronology, Sr/Nd, PbChemical Geology, Vol. 220, 3-4, pp. 165-189.Asia, ChinaGeochronology - early Cretaceous mafic igneous rocks
DS200912-0316
2009
Peng, Y.Huang, Z., Li, H., Zheng, Y., Peng, Y.The lithosphere of North Chin a craton from surface wave tomography.Earth and Planetary Science Letters, Vol. 288, 1-2, pp. 164-173.ChinaGeophysics - seismics
DS201906-1361
2019
Peng, Y.Wang, W., Walter, M.J., Peng, Y., Redfern, S., Wu, Z.Constraining olivine abundance and water content of the mantle at the 410 km discontinuity from the elasticity of olivine and wadsleyite.Earth and Planetary Science Letters, Vol. 519, pp. 1-11.Mantleolivine

Abstract: Velocity and density jumps across the 410-km seismic discontinuity generally indicate olivine contents of ?30 to 50 vol.% on the basis of the elastic properties of anhydrous olivine and wadsleyite, which is considerably less than the ?60% olivine in the widely accepted pyrolite model for the upper mantle. A possible explanation for this discrepancy is that water dissolved in olivine and wadsleyite affects their elastic properties in ways that can reconcile the pyrolitic model with seismic observations. In order to more fully constrain the olivine content of the upper mantle near the 410-km discontinuity, and to place constraints on the mantle water content at this depth, we determined the full elasticity of hydrous wadsleyite at the P-T conditions of the discontinuity based on density functional theory calculations. Together with previous determinations for the effect of water on olivine elasticity, we simultaneously modeled the density and seismic velocity jumps (??, , ) across the olivine-wadsleyite transition. Our models allow for several scenarios that can well reproduce the density and seismic velocity jumps across the 410-km discontinuity when compared to globally averaged seismic models. When the water content of olivine and wadsleyite is assumed to be equal as in a simple binary system, our modeling indicates a best fit for low water contents (<0.1 wt.%) with an olivine proportion of ?50%, suggesting a relatively dry, non-pyrolitic mantle at depths of the 410-km discontinuity. However, our modeling can be reconciled with a pyrolitic mantle if the water content in wadsleyite is ?0.9 wt.% and that in olivine is at its storage capacity of ?500-1500 ppm. The result would be consistent with a hydrous melt phase produced at depths just above the phase transition.
DS201907-1583
2019
Peng, Y.Wang, W., Walter, M.J., Peng, Y., Redfern, S., Wu, Z.Constraining olivine abundance and water content of the mantle at the 410 km discontinuity from the elasticity of olivine and wadsleyite.Earth and Planetary Science Letters, Vol. 519, pp. 1-11.Mantleboundary

Abstract: Velocity and density jumps across the 410-km seismic discontinuity generally indicate olivine contents of ?30 to 50 vol.% on the basis of the elastic properties of anhydrous olivine and wadsleyite, which is considerably less than the ?60% olivine in the widely accepted pyrolite model for the upper mantle. A possible explanation for this discrepancy is that water dissolved in olivine and wadsleyite affects their elastic properties in ways that can reconcile the pyrolitic model with seismic observations. In order to more fully constrain the olivine content of the upper mantle near the 410-km discontinuity, and to place constraints on the mantle water content at this depth, we determined the full elasticity of hydrous wadsleyite at the P-T conditions of the discontinuity based on density functional theory calculations. Together with previous determinations for the effect of water on olivine elasticity, we simultaneously modeled the density and seismic velocity jumps (??, , ) across the olivine-wadsleyite transition. Our models allow for several scenarios that can well reproduce the density and seismic velocity jumps across the 410-km discontinuity when compared to globally averaged seismic models. When the water content of olivine and wadsleyite is assumed to be equal as in a simple binary system, our modeling indicates a best fit for low water contents (<0.1 wt.%) with an olivine proportion of ?50%, suggesting a relatively dry, non-pyrolitic mantle at depths of the 410-km discontinuity. However, our modeling can be reconciled with a pyrolitic mantle if the water content in wadsleyite is ?0.9 wt.% and that in olivine is at its storage capacity of ?500-1500 ppm. The result would be consistent with a hydrous melt phase produced at depths just above the phase transition.
DS202012-2247
2021
Peng, Y.Saha, S., Peng, Y., Dasgupta, R., Mookherjee, M., Fischer, K.M.Assessing the presence of volatile-bearing mineral phases in the cratonic mantle as a possible cause of mid-lithospheric discontinuities.Earth and Planetary Letters, Vol.. 553, 116602, 12p. PdfMantlecratons

Abstract: A number of possible hypotheses have been proposed to explain the origin of mid-lithospheric discontinuities (MLDs), typically characterized by ?2-6% reductions in seismic shear wave velocity (VS) at depths of 60 km to ?150 km in the cratonic sub-continental lithospheric mantle (SCLM). One such hypothesis is the presence of low-shear wave velocity, hydrous and carbonate mineral phases. Although, the presence of hydrous silicates and carbonates can cause a reduction in the shear wave velocity of mantle domains, the contribution of volatile metasomatism to the origins of MLDs has remained incompletely evaluated. To assess the metasomatic origin of MLDs, we compiled experimental phase assemblages, phase proportions, and phase compositions from the literature in peridotite + H2O, peridotite + CO2, and peridotite + H2O + CO2 systems at P-T conditions where hydrous silicate and/or carbonate minerals are stable. By comparing the experimental assemblages with the compiled bulk peridotite compositions for cratons, we bracket plausible proportions and compositions of hydrous silicate and carbonate mineral phases that can be expected in cratonic SCLMs. Based on the CaO and K2O contents of cratonic peridotite xenoliths and the estimated upper limit of CO2 content in SCLM, ??10 vol.% pargasitic amphibole, ??2.1 vol.% phlogopite and ??0.2 vol.% magnesite solid solution can be stable in the SCLM. We also present new elasticity data for the pargasite end member of amphibole based on first principles simulations for more accurate estimates of aggregate VS for metasomatized domains in cratonic mantle. Using the bracketed phase compositions, phase proportions, and updated values of elastic constants for relevant mineral end members, we further calculate aggregate VS at MLD depths for three seismic stations in the northern continental U.S. Depending on the choice of background wave speeds of unmetasomatized peridotite and the cratonic geotherm, the composition and abundance of volatile-bearing mineral phases bracketed here can explain as much as 2.01 to 3.01% reduction in VS. While various craton formation scenarios allow formation of the amphibole and phlogopite abundances bracketed here, presence of volatile-bearing phases in an average cratonic SCLM composition cannot explain the entire range of velocity reductions observed at MLDs. Other possible velocity reduction mechanisms thus must be considered to explain the full estimated range of shear wave speed reduction at MLD depths globally.
DS202204-0533
2022
Peng, Y.Peng, Y., Manthilake, G., Mookherjee, M.Electrical conductivity of metasomatized lithology in subcontinental lithosphere.American Mineralogist, Vol. 107, pp. 343-349.Mantlemetasomatism

Abstract: A plausible origin of the seismically observed mid-lithospheric discontinuity (MLD) in the subcontinental lithosphere is mantle metasomatism. The metasomatized mantle is likely to stabilize hydrous phases such as amphiboles. The existing electrical conductivity data on amphiboles vary significantly. The electrical conductivity of hornblendite is much higher than that of tremolite. Thus, if hornblendite truly represents the amphibole varieties in MLD regions, then it is likely that amphibole will cause high electrical conductivity anomalies at MLD depths. However, this is inconsistent with the magnetotelluric observations across MLD depths. Hence, to better understand this discrepancy in electrical conductivity data of amphiboles and to evaluate whether MLD could be caused by metasomatism, we determined the electrical conductivity of a natural metasomatized rock sample. The metasomatized rock sample consists of ~87% diopside pyroxene, ~9% sodium-bearing tremolite amphibole, and ~3% albite feldspar. We collected the electrical conductivity data at ~3.0 GPa, i.e., the depth relevant to MLD. We also spanned a temperature range between 400 to 1000 K. We found that the electrical conductivity of this metasomatized rock sample increases with temperature. The temperature dependence of the electrical conductivity exhibits two distinct regimes. At low temperatures <700 K, the electrical conductivity is dominated by the conduction in the solid state. At temperatures >775 K, the conductivity increases, and it is likely to be dominated by the conduction of aqueous fluids due to partial dehydration. The main distinction between the current study and the prior studies on the electrical conductivity of amphiboles or amphibole-bearing rocks is the sodium (Na) content in amphiboles of the assemblage. Moreover, it is likely that the higher Na content in amphiboles leads to higher electrical conductivity. Pargasite and edenite amphiboles are the most common amphibole varieties in the metasomatized mantle, and our study on Na-bearing tremolite is the closest analog of these amphiboles. Comparison of the electrical conductivity results with the magnetotelluric observations constrains the amphibole abundance at MLD depths to <1.5%. Such a low-modal proportion of amphiboles could only reduce the seismic shear wave velocity by 0.4-0.5%, which is significantly lower than the observed velocity reduction of 2-6%. Thus, it might be challenging to explain both seismic and magnetotelluric observations at MLD simultaneously.
DS2001-1313
2001
Peng, Z.Zhi, X., Peng, Z., Chen, D.The longevity of subcontinental lithospheric mantle beneath Jiangsu Anhui region - the OS isotope model ageScience in China Series D Earth Science, Vol. 44, No. 12, pp. 1110-18.ChinaGeochronology, Mantle derived peridotite xenoliths
DS200612-1154
2005
Peng, Z.Reisberg, L., Zhi, X., Lorand, J.P., Wagner, C., Peng, Z., Zimmermann, C.Re Os S systematics of spinel peridotite xenoliths from east central China: evidence for contrasting effects of melt percolation.Earth and Planetary Science Letters, Vol. 239, 3-4, pp. 286-308.ChinaGeochronology
DS1991-1921
1991
Peng, Z.C.Zartman, R.E., Futa, K., Peng, Z.C.A comparison of Sr-Neodymium-Palladium isotopes in young and old continental lithosphericmantle: Patagonia and eastern ChinaAustralian Journal of Earth Science, Vol. 38, pp. 545-557China, South AmericaMantle, Geochronology
DS1991-1326
1991
Peng GenyongPeng Genyong, Bao Peisheng, Wang Xibin, Hao ZiguoOrigin of Pl-lherzolite in the Hongguleleng ophiolite, XinjiangActa Petrologica et Mineralogia, Chi, Vol. 10, pt. 2, May p. 126. English abstract onlyChinaLherzolite, Ophiolite
DS1985-0523
1985
Peng zhizhong, LU QI.Peng zhizhong, LU QI.The Crystal Structure of Yimengite.*chiScientia Sinica Ser. B., *CHI, Vol. 28, No. 8, pp. 882-887ChinaCrystallography
DS200512-0837
2005
Penha, U.C.Penha, U.C., Karfunkel, J., Angeli, N.Diamondiferous deposits in the Jequitai area ( Minas Gerais, Brazil): a consequence of neotectonic processes.Neues Jahrbuch fur Geologie und Palaontologie , Band 236, Heft 1-2, pp. 207-224.South America, Brazil, Minas GeraisTectonics
DS200612-1070
2005
Penha, U.C.Penha, U.C., Karfunkel, J., Angeli, N.Diamondiferous deposits in the Jequitai area (Minas Gerais, Brazil): a consequence of neotectonic processes.Neues Jahrbuch fur Geologie und Palaontologie , Vol. 236, 3, pp. 207-224.South America, Brazil, Minas GeraisTectonics - diamond deposit
DS1989-1012
1989
Penman, C.Merry, S., Penman, C., Pun, P.The Canadian connection: business onlineDatabase, Vol. 12, No. 5, pp. 15-27. Database # 18155GlobalDatabase useage, Business
DS201902-0306
2018
PennaPeres Rocha, M., Assumpcao, M., Fuck, R., Araujo de Azevedo, P., Penna, Crepaldi Affonso, G.M., Sousa Lima Costa, I., Farrapo Albuquetque, D.Llithosphere expression of the boundary between the Amazonian and extra-Amazonian domains of the South American platform from travel time seismic tomography.Researchgate, AGU 1p. Preprint pdfSouth Americacraton

Abstract: The South American platform is the stable part of the South American plate, unaffected by the orogenesis of the Andes and the Caribbean. Its basement is composed of Archean and Proterozoic cratonic blocks amalgamated by mobile belts, and can be separated in two large domains or continental masses: 1) The Amazonian, Northwest-west portion, including the Amazonian craton, related to the Laurentia supercontinent; and 2) the extra-Amazonian, Central-southeast or Brasiliano domain, related to West Gondwana, formed of several paleocontinental fragments, where the São Francisco and Rio de La Plata cratons and the Paranapanema block are the largest. It has been suggested that these two domains are separated by the Transbrasiliano Lineament to the south and the Araguaia Fold Belt to the north. Teleseismic P waves from 4,989 earthquakes recorded by 339 stations operated mainly in Brazil in the last 25 years have been used for relative-time tomography. The Amazonian domain is predominantly characterized by higher velocities. The SW (extra-Amazonian) domain is characterized by several blocks with high velocities, such as in and around the Sao Francisco Craton, and the Paranapanema block. Results of P-wave travel time tomography allowed to observe a strong low-velocity anomaly near 100-200 km depth following the Araguaia-Paraguay fold belt. This strong low-velocity anomaly could be considered the limit between these two domains, reaching lithospheric depths, and does not necessarily follow the Transbrasiliano lineament, especially in its southern portion.
DS1995-1477
1995
Penna, G.M.Penna, G.M.Tax treatment of mine reclamation fundsMining Tax Strategies, Held Feb. 1995, 27pCanadaTaxation, Mine reclamation
DS201904-0734
2019
Pennacchioni, G.Faccenda, M., Ferreira, A.M.G., Tisato, N., Lithgow-Bertelloni, C., Stixrude, L., Pennacchioni, G.Extrinsic elastic anisotropy in a compositionally heterogeneous Earth's mantle.Journal of Geophysical Research: Solid Earth, https://doi,org/ 10.1029/2018JB016482Mantleanistropy

Abstract: Several theoretical studies indicate that a substantial fraction of the measured seismic anisotropy could be interpreted as extrinsic anisotropy associated with compositional layering in rocks, reducing the significance of strain?induced intrinsic anisotropy. Here we quantify the potential contribution of grain?scale and rock?scale compositional anisotropy to the observations by (i) combining effective medium theories with realistic estimates of mineral isotropic elastic properties and (ii) measuring velocities of synthetic seismic waves propagating through modeled strain?induced microstructures. It is shown that for typical mantle and oceanic crust subsolidus compositions, rock?scale compositional layering does not generate any substantial extrinsic anisotropy (<1%) because of the limited contrast in isotropic elastic moduli among different rocks. Quasi?laminated structures observed in subducting slabs using P and S wave scattering are often invoked as a source of extrinsic anisotropy, but our calculations show that they only generate minor seismic anisotropy (<0.1-0.2% of Vp and Vs radial anisotropy). More generally, rock?scale compositional layering, when present, cannot be detected with seismic anisotropy studies but mainly with wave scattering. In contrast, when grain?scale layering is present, significant extrinsic anisotropy could exist in vertically limited levels of the mantle such as in a mid?ocean ridge basalt?rich lower transition zone or in the uppermost lower mantle where foliated basalts and pyrolites display up to 2-3% Vp and 3-6% Vs radial anisotropy. Thus, seismic anisotropy observed around the 660?km discontinuity could be possibly related to grain?scale shape?preferred orientation. Extrinsic anisotropy can form also in a compositionally homogeneous mantle, where velocity variations associated with major phase transitions can generate up to 1% of positive radial anisotropy.
DS202105-0776
2021
Pennacchioni, L.Martirosyan, N.S., Efthimiopoulos, I., Pennacchioni, L., Wirth, R., Jahn, S., Koch-Muller, M.Effect of catonic substitution on the pressure -induced phase transition in calcium carbonate.American Mineralogist, Vol. 106, pp. 549-558. pdfMantledeep carbon cycle
DS2002-1718
2002
Penney, G.T.Wilton, D.H.C., Taylor, R.C., Sylvester, P.J., Penney, G.T.A review of kimberlitic and ultramafic lamprophyre intrusives from northern Labrador. Archean Nain Province.Newfoundland Current Research, No. 02-1, pp. 343-52.LabradorHopedale, Aillik-Makkovik, Ford's Bight, Saglek - Torngat
DS200412-1522
2004
Penney, G.T.Penney, G.T., Wilton, D., Sylvester, P.Geochemical investigation of kimberlite and lamproite intrusions in northeastern Labrador and Killiniq Island, Nunavut.Geological Association of Canada Abstract Volume, May 12-14, SS14P01, p. 273.abstractCanada, NunavutDykes - Torngat
DS200412-2133
2002
Penney, G.T.Wilton, D.H.C., Taylor, R.C., Sylvester, P.J., Penney, G.T.A review of kimberlitic and ultramafic lamprophyre intrusives from northern Labrador. Archean Nain Province.Newfoundland Current Research, No. 02-1, pp. 343-52.Canada, Quebec, LabradorHopedale, Aillik-Makkovik, Ford's Bight Saglek - Torngat
DS1960-0946
1968
Penniman, H.W.Ekman, A., Parker, I.H., Storms, W.H., Penniman, H.W., DittmarOld Mines and Ghost Camps of CaliforniaFrontier Book Co. Fort Davis Texas, P. 26; P. 67.United States, California, West CoastBlank
DS1900-0072
1901
Penning, W.H.Penning, W.H.Gold and Diamonds. South African Facts and InferencesLondon: Baillere, Tindall And Co., 77P.Africa, South AfricaGeology, Kimberley, Janlib
DS1975-0595
1977
Penninkilampi, J.Paarma, H., Vartiainen, H., Penninkilampi, J.Aspects of Photo geological Interpretation of Sokli Carbonatite Massif.Institute of Mining and Metallurgy. SPECIAL Publishing, PP. 25-29.GlobalRemote, Sensing
DS201212-0549
2012
Penniston-Dorland, S.Penniston-Dorland, S., Walker, R.J., Pitcher, L., Sorensen, S.S.Mantle crust interactions in a paleosubduction zone: evidence from highly siderophile element systematics of eclogite and related rocks.Earth and Planetary Science Letters, Vol. 319-320, pp. 295-306.MantleSubduction
DS201212-0798
2012
Penniston-Dorland, S.C.Yakob, J.L., Feineman, M.D., Deane, J.A., Eggler, D.H., Penniston-Dorland, S.C.Lithium partitioning between olivine and diopside at upper mantle conditions: as experimental study.Earth and Planetary Science Letters, Vol. 329-330, pp. 11-21.MantleTechnology
DS2002-0366
2002
Pennock, G.De Meer, S., Drury, M., De Bresser, H., Pennock, G.Deformation mechanisms, rheology and tectonics : current status and future perspectives.Geological Society of London (U.K.), 424p.$ 167.00 http://bookshop.geolsoc.org.ukMantleBook - tectonics, deformation, lithosphere
DS2003-0324
2003
Pennock, G.De Meer, S., Drury, M., De Bresser, H., Pennock, G.Deformation mechanisms, rheology and tectonics: current status and futureGeological Society of London Special Paper, No. 200, 424p. $ 240. www.geosoc.orgMantleCrustal layers, tectonics, structure, Book
DS2002-0367
2002
Pennock, G.M.De Meer, S., Drury, M.R., De Bresser, J.H.P., Pennock, G.M.Current issues and new developments in deformation mechanisms, rheology and tectonics.Geological Society of London Special Publication, No.200, pp. 1-28.BlankReview
DS1984-0579
1984
PennwellPennwellPrincipal Structural Features of KansasPennwell, P.o. Box 21288, Tulsa Oklahoma., 1:500, 000United States, KansasTectonics, Mid Continent
DS1984-0580
1984
PennwellPennwellPrincipal Structural Features of LousianaPennweel, P.o. Box 21288, Tulsa Oklahoma., 1:500, 000United States, LouisianaTectonics, Mid Continent
DS200512-0838
2004
Penny, S.R.Penny, S.R., Allen, R.M., Harrison, S., Lees, T.C., Murphy, F.C., Norman, A.R., Roberts, P.A.A global scale exploration risk analysis technique to determine the best mineral belts for exploration.Transactions of Institute of Mining and Metallurgy, Vol. 113, September pp. 183-194.Economics - risk analysis
DS1981-0105
1981
Pennycook, S.Bursill, L.A., Egerton, R.F., Thomas, J.M., Pennycook, S.High Resolution Imaging and Electron Energy Loss Studies Of platelet Defects in Diamond.Faraday Transactions, 2ND. SERIES, Vol. 77, No. 8, PP. 1367-1373.GlobalDiamond, Natural
DS1983-0235
1983
Penrose, B.Freeman, S., Penrose, B.Bomber With Diamond Chips on His ShoulderSunday Times, SEPTEMBER 11TH.GlobalIdb, Politics
DS1900-0584
1907
Penrose, R.A.F. JR.Penrose, R.A.F. JR.The Premier Diamond Mine, Transvaal, South AfricaEconomic Geology, Vol. 2, PP. 275-283.Africa, South AfricaGeology
DS1997-0899
1997
Penswick, D.P.Penswick, D.P.Technical note: the Palabora high reach rig..Journal of African Institute of Mining and Metallurgy, March/April pp. 69-72South AfricaMining, underground, rare earths, polymetallics, Deposit - Palabora
DS201412-0374
2014
Penumado, D.Howarth, G.H., Sobolev, N.V., Pernet-Fisher, J.F., Barry, P.H., Penumado, D., Puplampu, S., Ketcham, R.A., Maisano, J.A., Taylor, D., Taylor, L.A.The secondary origin of diamonds: multi-modal radiation tomography of Diamondiferous mantle eclogites.International Geology Review, Vol. 56, 9, pp. 1172-1180.Russia, Siberia3D
DS2001-0904
2001
People's DailyPeople's DailySecurity council renews U.N. mission in Sierra LeonePeople's Daily, Sept. 19, 2p.Sierra LeoneNews item, Conflict diamonds
DS200612-1071
2006
Peoples Daily OnlinePeoples Daily OnlineUK firm to invest 4 million pounds in Zimbabwe's mining sector. African Consolidated Resources.... ACR has diamond, platinum and gold claims.African Consolidated Resources, July 10, 1/2p.Africa, ZimbabweNews item - African Consolidated
DS200712-0828
2006
People's Daily OnlinePeople's Daily OnlineDe Beers calls for tougher measures for conflict diamonds.People's Daily Online, Nov. 2, 1/2p.GlobalNews item - Kimberley Process
DS200712-0829
2007
Peoples Democratic Republic of Algeria.Peoples Democratic Republic of Algeria.Diamond - new province south of Algeria.Democratic Republic of Algeria, Handout at Mines & Money Conference 11p. refs.Africa, AlgeriaDiamond history
DS1994-1361
1994
Peper, T.Peper, T.Tectonic and eustatic control on Albian shallowing (Viking and Paddy Formations) Western Canada ForelandGeological Society of America (GSA), Vol. 106, Feb. pp. 253-64.Alberta, Western CanadaBasin - Western Canada Foreland Basin, Tectonics
DS200412-1569
2004
Pepin, R.Porcelli, D., Pepin, R., Halliday, A., Ballentine, C.Xe, mantle degassing and atmospheric closure.Geochimica et Cosmochimica Acta, 13th Goldschmidt Conference held Copenhagen Denmark, Vol. 68, 11 Supp. July, ABSTRACT p.A553.MantleDegassing
DS200612-1072
2006
Pepin, R.O.Pepin, R.O., Porcelli, D.Xenon isotope systematics, giant impacts and mantle degassing on the early Earth.Earth and Planetary Science Letters, Vol. 250, 3-4, pp. 470-485.MantleGeochronology
DS200712-0830
2006
Pepin, R.O.Pepin, R.O., Porcelli, D.Xenon isotope systematics, giant impacts, and mantle degassing on the early Earth.Earth and Planetary Science Letters, Vol. 250, 3-4, Oct. 30, pp. 470-485.MantleGeochronology
DS1984-0162
1984
Pepin, S.V.Bokiy, G.B., Nikitin, A.V., Pepin, S.V.Chemical Transport of Carbon by Nitrogen Containing Intermediates in Natural Diamond Synthesis.Doklady Academy of Science USSR, Earth Science Section., Vol. 266, No. 1-6, MAY PP. 169-172.RussiaGenesis, Diamond Morphology
DS1983-0174
1983
Pe-Piper, G.Clarke, D.B., Muecke, G.K., Pe-Piper, G.The Lamprophyres of Ubekendt Elland, West Greenland: Products of Renewed Partial Melting or Extreme Differentiation?Contributions to Mineralogy and Petrology, Vol. 83, No. 1-2, PP. 117-127.GreenlandRelated Rocks
DS1983-0175
1983
Pe-Piper, G.G.Clarke, D.B., Pe-Piper, G.G.Multiply Exsolved Clinopyroxene Megacrysts from the Frank Smith Mine Cape Province, South Africa.Lithos, Vol. 16, No. 1, PP. 75-84.South Africa, Cape ProvincePetrography, Xenoliths, Analyses, Genesis, Kimberlite
DS2002-0677
2002
Peppin, W.A.Hauff, P.L., Coulter, D., Koll, G., Peters, D.C., Peppin, W.A.An overview of hyper spectral remote sensing as applied to precious metals and diamond deposits.11th. Quadrennial Iagod Symposium And Geocongress 2002 Held Windhoek, Abstract p. 27.GlobalRemote sensing - hyperspectral
DS201112-0557
2011
Peppin, W.A.Kruse,F.A., Bedell, R.L., Taranik, J.V., Peppin, W.A., Weatherbee, O., Calvin, W.M.Mapping alteration minerals at prospect, outcrop and drill core scales using imagining spectroscopy.International Journal of Remote Sensing, Vol. 33, 6, pp. 1780-1798.GlobalSpectroscopy - not specific to diamonds
DS202012-2227
2013
Perceira, V.P.Manfredi, T.K., Nes, A.C.B., Perceira, V.P., Barbanson, L.The parasite-(Ce) mineralization associated with the Fazenda Varela carbonatite ( Correia Pinto, SC).Pesquisas Geosciencias, Dec. 14p. PdfSouth America, Brazil, Santa Catarinadeposit - Fazenda

Abstract: The Fazenda Varela carbonatite is part of the Lages alkaline complex (Late Cretaceous). The carbonatite occurs as abundant veins that cut the sandstones of the Rio Bonito Formation which are strongly brecciated and metasomatized. Petrography, geochemistry, X-ray diffraction, scanning electron microscopy and electron microprobe data allowed the identification and classification of REE fluorcarbonates. The carbonatite is composed essentially by ankerite and Fe-dolomite and was strongly affected for tardi and post magmatic events. The hydrothermal fluids percolated through fractures and grain boundaries and formed hydrothermal domains composed of barite, apatite, quartz, calcite, Fe-dolomite, and parisite-(Ce). In these domains, parisite-(Ce) occurs as well-developed fibrous to fibroradiated crystals. Parisite-(Ce) also occurs in hydrothermal veins that cut the metasomatized host rock. The parisite-(Ce) crystals are heterogeneous, occur in syntaxial growth with synchysite-(Ce), and have excess of Ca and REE and F depletions in relation to an ideal composition. The parasite-(Ce) mineralization formed from a fluid with low F activity that interacted with the rock and leached preferentially the LREE, which were likely transported as chlorine complexes.
DS1997-1158
1997
Perchuc, E.Thybo, H., Perchuc, E.The seismic 8 degrees discontinuity and partial melting in continentalmantle.Science, Vol. 275, No. 5306, Mar. 14, pp. 1626-28.MantleMelting, Boundary - Discontinuity
DS2002-0066
2002
Perchuc, E.Artemieva, I.M., Mooney, W.D., Perchuc, E., Thybo, H.Processes of lithosphere evolution: new evidence on the structure of the continental crust and uppermost mantle.Tectonophysics, Vol. 358, 1-4, pp. 1-15.MantleTectonics
DS2003-1377
2003
Perchuc, E.Thybo, H., Neilsen, L., Perchuc, E.Seismic scattering at the top of the mantle transition zoneEarth and Planetary Science Letters, Vol. 216. 3. pp. 259-269.MantleGeophyics - seismics
DS200412-1990
2003
Perchuc, E.Thybo, H., Neilsen, L., Perchuc, E.Seismic scattering at the top of the mantle transition zone.Earth and Planetary Science Letters, Vol. 216. 3. pp. 259-269.MantleGeophyics - seismics
DS2001-1092
2001
Perchuck, L.L.Smit, C.A., Van Reenan, D.D., Perchuck, L.L.P T conditions of decompression of the Limpopo high grade terrane: record of shear zones.Journal of Metamorphic Geology, Vol. 19, No. 3, pp. 249-68.South Africametamorphism, Limpopo Terrain
DS2001-0916
2001
PerchukPhilippot, P., Blichertoft, Perchuk, Costa, GerasimovLutetium(Lu)- Hafnium(Hf) and Argon- Argon chronology supports extreme rate of subduction zone metamorphism deduced geospeedometryTectonophysics, Vol. 342, No. 2, pp. 23-38.MantleGeochronology, Argon, Lutetium, Hafnium, Subduction
DS1999-0553
1999
Perchuk, A.Perchuk, A., Philpott, P., Erdmer, P., Filian, M.Rates of thermal equilibrium at the onset of subduction deduced from diffusion modeling of eclogitic garnets...Geology, Vol. 27, No. 6, June, pp. 531-4.YukonTanan Terrane - not specific to diamonds, Garnets - eclogites
DS1993-1222
1993
Perchuk, A.L.Perchuk, A.L.Excess pressure in garnet from eclogite, as derived from the reaction Ab=Jd+ quartz.Doklady Academy of Sciences USSR, Earth Science Section, Vol. 316, No. 5, pp. 157-161.NorwayEclogite, Coesite
DS1995-1478
1995
Perchuk, A.L.Perchuk, A.L.Fluid inclusions in Great Caucasus eclogitesGeochemistry International, Vol. 32, No. 2, pp. 56-61.Russia, AsiaEclogites
DS1996-1106
1996
Perchuk, A.L.Perchuk, A.L., Varlamov, D.A.A new type of prograde heterogeneity in garnet based on a study of Great-Caucasus eclogites.Geochemistry International, Vol. 33, No. 8, pp. 101-116.RussiaEclogites, Mineralogy -garnets
DS2000-0753
2000
Perchuk, A.L.Perchuk, A.L., Philippot, P.Geospeedometry and time scales of high pressure metamorphismInternational Geology Review, Vol. 42, No. 3, March pp. 207-223.Globalultra high pressure (UHP)
DS2002-1241
2002
Perchuk, A.L.Perchuk, A.L.Eclogites of the Bergen Arcs Complex, Norway: petrology and mineral chronometryPetrology, Vol. 10, 2, pp. 99-118.NorwayEclogites
DS2002-1242
2002
Perchuk, A.L.Perchuk, A.L.Ecologites of the Bergen Arcs Complex, Norway" petrology and mineral chronometryPetrology, Vol.10,2,pp.99-118.NorwayEclogites
DS200512-0839
2005
Perchuk, A.L.Perchuk, A.L., Gerya, T.V.Subsidence and exhumation dynamics of eclogites in the Yukon-Tanana Terrane, Canadian Cordillera: petrological reconstructions and geodynamic modeling.Petrology, Vol. 13, 3, pp. 253-266.Canada, YukonEclogite
DS200612-1073
2005
Perchuk, A.L.Perchuk, A.L., Burchard, M., Maresch, W.V., Schertl, H-P.Fluid mediated modification of garnet interiors under ultrahigh pressure conditions.Terra Nova, Vol. 17, 6, pp. 545-553.MantleUHP
DS200812-0880
2008
Perchuk, A.L.Perchuk, A.L.Unusual inclusions in garnet from the diamond bearing gneiss of the Erzgebirge, Germany.Geochemistry International, Vol. 46, 3, pp. 296-303.Europe, GermanyDiamond inclusions
DS200812-0881
2008
Perchuk, A.L.Perchuk, A.L.Melt inclusions in garnet from Diamondiferous gneiss, Erzgebirge Germany.Doklady Earth Sciences, Vol. 421,1, pp. 832-834.Europe, GermanyMetamorphic rocks
DS200812-0882
2008
Perchuk, A.L.Perchuk, A.L., Yapaskurt, V.O., Davydova, V.V.Melt inclusions in eclogite garnet: experimental study of natural processes.Russian Geology and Geophysics, Vol. 49, 4, pp. 310-312.Canada, YukonEclogite - melting
DS201012-0573
2009
Perchuk, A.L.Perchuk, A.L., Davydova, V.V., Burchard, M., Maresch, W.V., Schertl, H.P., Yapaskurt, V.O., Safonov, O.G.Modification of mineral inclusions in garnet under high pressure conditions: experimental simulation and application to carbonate silicate rocks of KokchetetavRussian Geology and Geophysics, Vol. 50, 12, pp. 1153-1168.RussiaMineralogy
DS201412-0672
2013
Perchuk, A.L.Perchuk, A.L., Shur, M.Yu., Yapaskurt, V.O., Podgornova, S.T.Experimental modeling of mantle metasomatism coupled with eclogitization of crustal material in a subduction zone.Petrology, Vol. 21, 6, pp. 579-598.MantleSubduction
DS201707-1356
2016
Perchuk, A.L.Perchuk, A.L., Safonov, O.G., Smit, C.A., van Reenen, D.D., Zkharov, V.S., Gerya, T.V.Precambrian ultra hot orogenic factory: making and reworking of continental crust.Tectonophysics, in press availableMantleUHP

Abstract: Mechanisms of Precambrian orogeny and their contribution to the origin of ultrahigh temperature granulites, granite-greenstone terranes and net crustal growth remain debatable. Here, we use 2D numerical models with 150 °C higher mantle temperatures compared to present day conditions to investigate physical and petrological controls of Precambrian orogeny during forced continental plates convergence. Numerical experiments show that convergence between two relatively thin blocks of continental lithosphere with fertile mantle creates a short-lived cold collisional belt that later becomes absorbed by a long-lived thick and flat ultra-hot accretionary orogen with Moho temperatures of 700–1100 °C. The orogen underlain by hot partially molten depleted asthenospheric mantle spreads with plate tectonic rates towards the incoming lithospheric block. The accretionary orogeny is driven by delamination of incoming lithospheric mantle with attached mafic lower crust and invasion of the hot partially molten asthenospheric wedge under the accreted crust. A very fast convective cell forms atop the subducting slab, in which hot asthenospheric mantle rises against the motion of the slab and transports heat towards the moving orogenic front. Juvenile crustal growth during the orogeny is accompanied by net crustal loss due to the lower crust subduction. Stability of an ultra-hot orogeny is critically dependent on the presence of relatively thin and warm continental lithosphere with thin crust and dense fertile mantle roots subjected to plate convergence. Increased thickness of the continental crust and subcontinental lithospheric mantle, pronounced buoyancy of the lithospheric roots, and decreased mantle and continental Moho temperature favor colder and more collision-like orogenic styles with thick crust, reduced magmatic activity, lowered metamorphic temperatures, and decreased degree of crustal modification. Our numerical modeling results thus indicate that different types of orogens (cold, mixed-hot and ultra-hot) could be created at the same time in the Early Earth, depending on compositional and thermal structures of interacting continental blocks.
DS201812-2861
2018
Perchuk, A.L.Perchuk, A.L., Yapaskurt, V.O., Zinovieva, N.G., Shur, M. Yu.Experimental evidence for opposite fluxes of sodium, potassium, and CO2 during glaucophane schist interaction with harzburgite and websterite in subduction zones.Petrology, Vol. 26, 6, pp. 599-616.Mantlemetasomatism

Abstract: This paper reports the results of high-pressure experimental modeling of interaction between glaucophane schist and harzburgite or websterite for the evaluation of the influence of mantle material on the input-output of components and character of metasomatic transformations at the crust-mantle boundary in the subduction zone. In all experiments, glaucophane schist (proxy for oceanic crust) containing volatile components (H2O and CO2) incorporated in hydrous minerals (amphiboles, phengite, and epidote) and calcite was loaded into the bottom of each capsule and overlain by mantle material. During the experiments at a temperature of 800°C and a pressure of 2.9 GPa, which correspond to the conditions of a hot subduction zone, the schist underwent partial (up to 10%) eclogitization with the formation of the anhydrous assemblage omphacite + garnet + quartz ± magnesite ± potassic phase. Carbonate and a potassic phase were formed only in the experiments with websterite in the upper layer. A reaction zone was formed at the base of the websterite layer, where newly formed omphacite, quartz, and orthopyroxene replaced in part initial pyroxenes. Orthopyroxene and phlogopite (or an unidentified potassic phase) were formed in the reaction zone at the base of the harzburgite layer; among the initial minerals, only orthopyroxene relicts were preserved. Above the reaction zones produced by diffusion metasomatism, new phases developed locally, mainly at grain boundaries: newly formed orthopyroxene and magnesite were observed in harzburgite, and omphacite and quartz, in websterite. Alterations along grain boundaries extended much further than the reaction zones, which indicates that fluid infiltration dominated over diffusion in the experiments. The experiments demonstrated that the H2O-CO2 fluid with dissolved major components released from the glaucophane schist can produce mineral assemblages of different chemical compositions in mantle materials: Na-bearing in websterite and K-bearing in harzburgite. The complementary components, K2O and CO2 for the websterite layer and Na2O for the harzburgite layer, are fixed in the initial glaucophane schist layer. The distinguished separation of alkalis and CO2 at the crust-mantle boundary can affect the character of metasomatism in the mantle wedge, primary magma compositions, and the chemical evolution of the rocks of the subducting slab.
DS201901-0055
2018
Perchuk, A.L.Perchuk, A.L., Safonov, O.G., Smit, C.A., van Reenen, D.D., Zakharov, V.S., Gerya, T.V.Precambrian ultra-hot orogenic factory: making and reworking of continental crust.Tectonophysics, Vol. 746, pp. 572-586.Mantlesubduction

Abstract: Mechanisms of Precambrian orogeny and their contribution to the origin of ultrahigh temperature granulites, granite-greenstone terranes and net crustal growth remain debatable. Here, we use 2D numerical models with 150 °C higher mantle temperatures compared to present day conditions to investigate physical and petrological controls of Precambrian orogeny during forced continental plates convergence. Numerical experiments show that convergence between two relatively thin blocks of continental lithosphere with fertile mantle creates a short-lived cold collisional belt that later becomes absorbed by a long-lived thick and flat ultra-hot accretionary orogen with Moho temperatures of 700-1100 °C. The orogen underlain by hot partially molten depleted asthenospheric mantle spreads with plate tectonic rates towards the incoming lithospheric block. The accretionary orogeny is driven by delamination of incoming lithospheric mantle with attached mafic lower crust and invasion of the hot partially molten asthenospheric wedge under the accreted crust. A very fast convective cell forms atop the subducting slab, in which hot asthenospheric mantle rises against the motion of the slab and transports heat towards the moving orogenic front. Juvenile crustal growth during the orogeny is accompanied by net crustal loss due to the lower crust subduction. Stability of an ultra-hot orogeny is critically dependent on the presence of relatively thin and warm continental lithosphere with thin crust and dense fertile mantle roots subjected to plate convergence. Increased thickness of the continental crust and subcontinental lithospheric mantle, pronounced buoyancy of the lithospheric roots, and decreased mantle and continental Moho temperature favor colder and more collision-like orogenic styles with thick crust, reduced magmatic activity, lowered metamorphic temperatures, and decreased degree of crustal modification. Our numerical modeling results thus indicate that different types of orogens (cold, mixed-hot and ultra-hot) could be created at the same time in the Early Earth, depending on compositional and thermal structures of interacting continental blocks.
DS201906-1333
2019
Perchuk, A.L.Perchuk, A.L., Zakharov, V.S., Gerya, T.V., Brown, M.Hotter mantle but colder subduction in the Precambrian: what are the implications?Precambrian Research, Vol. 330, pp. 20-34.Mantlesubduction

Abstract: On contemporary Earth, subduction recycles mafic oceanic crust and associated volatile elements, creating new silicic continental crust in volcanic arcs. However, if the mantle was hotter in the Precambrian, the style of subduction, the depth of devolatilization and the formation of silicic continental crust may have been different. Consequently, the generation of the tonalite-trondhjemite-granodiorite (TTG) suite, which is characteristic of Archean crust, may not have been related to subduction. Here, we use a two-dimensional numerical magmatic-thermomechanical model to investigate intraoceanic subduction for contemporary mantle conditions and at higher mantle temperatures, as appropriate to the Precambrian. In each case, we characterize the thermal structure of the subducting plate and investigate magma compositions and production rates. We use these results to assess the potential growth of silicic continental crust associated with intraoceanic subduction at different mantle temperatures. For the Precambrian, in a set of experiments with ?T?=?150?K and decreasing subducting plate velocity, we find that the contemporary style of subduction was preceded by an arc-free regime dominated by rapid trench rollback and vigorous upwelling of asthenospheric mantle into the space created above the retreating slab. In this regime, formation of magmas by fluid-fluxed melting of the mantle is suppressed. Instead, decompression melting of upwelling asthenospheric mantle results in the widespread development of voluminous plateau-like basaltic magmas. In addition, retreating subduction at higher mantle temperature causes faster descent of the downgoing slab, leads to colder thermal gradients, similar to those associated with active subduction in the western Pacific today, and suppresses melting of the basaltic crust, limiting production of silicic (adakite-like) magmas. With increasing maturity of the subduction system, retreat of the subducting plate ceases, the role of decompression melting strongly decreases and fluid-fluxed melting of the mantle coupled with melting of the hydrated slab begins to produce basaltic and felsic arc volcanic rocks similar to those formed during contemporary subduction. In an additional series of individual experiments at various ?T, an increase of the mantle temperature above ?T?=?150?K leads to episodic and short-lived subduction accompanied by limited production of silicic continental crust. The results of our experimental study demonstrate that a hotter mantle in the Precambrian changes dramatically both the slab dynamics and the processes of magma generation and crustal growth associated with intraoceanic subduction zones. These changes may preclude growth of the early Precambrian silicic continental crust by processes that were dominantly similar to those associated with contemporary subduction.
DS202106-0964
2021
Perchuk, A.L.Perchuk, A.L., Sapegina, A.V., Safonov, O.G., Yapaskurt, V.O., Shatsky, V.S., Malkovets, V.G.Reduced amphibolite facies conditions in the Precambrian continental crust of the Siberian craton recorded by mafic granulite xenoliths from the Udachnaya kimberlite pipe, Yakutia.Precambrian Research, Vol. 357, 1061022, 14p. PdfRussia, Yakutiadeposit - Udachnaya

Abstract: It is widely accepted that granulite xenoliths from kimberlites provide a record of granulite facies metamorphism at the basement of cratons worldwide. However, application of the phase equilibria modeling for seven representative samples of mafic granulites from xenoliths of the Udachnaya kimberlite pipe, Yakutia, revealed that a granulitic garnet + clinopyroxene + plagioclase ± orthopyroxene ± amphibole ± scapolite mineral assemblage was likely formed in the middle crust under amphibolite facies conditions (600-650 °C and 0.8-1.0 GPa) in a deficiency of fluid. Clinopyroxene in the rocks is characterized by elevated aegirine content (up to 10 mol.%) both in the earlier magmatic cores and in the later metamorphic rim zones of the grains. Nevertheless, the phase equilibrium modeling for all samples indicates surprisingly reduced conditions, i.e. oxygen fugacity 1.6-3.3 log units below the FMQ (Fayalite-Magnetite-Quartz) buffer. In contrast, the coexistence of Fe-Ti oxides indicates temperatures of 850-990 °C and oxygen fugacity about lg(FMQ) ± 0.5, conditions which correspond to earlier stages of rock evolution. Reduction of oxygen fugacity during cooling is discussed in the context of the evolution of a complex fluid. The reconstructed P-T conditions for the final equilibration in the mafic granulites indicate that temperatures were ~250 °C higher than those extrapolated from the continental conductive geotherm of 35-40 µW/m2 deduced from peridotite xenoliths of the Udachnaya pipe. Although the granulites resided in the crust for a period for at least 1.4 Ga, they did not re-equilibrate to the temperatures of the geotherm, likely due to the blocking of mineral reactions under relatively low temperatures and fluid-deficient conditions
DS1996-1107
1996
Perchuk, E.Perchuk, E., Thybo, H.A new model of upper mantle P wave velocity below the Baltic shield-indication of partial melt in 95 Km-160Tectonophysics, Vol. 253, No. 3-4, March 20, pp. 227-245.Baltic Shield, Europe, Urals, UkraineMantle melt
DS200612-1397
2006
Perchuk, E.Suvorov, V.D., Melnik, E.A., Thybo, H., Perchuk, E., Parasotka, B.S.Seismic velocity model of the crust and uppermost mantle around the Mirnyi kimberlite field in Siberia.Tectonophysics, Vol. 420, 1-2, June 26, pp. 49-73.Russia, SiberiaGeophysics - seismic, Mirnyi
DS200812-0994
2008
Perchuk, L.Safonov, O., Perchuk, L., Litvin, Y., Chertkova, N., Butvina, V.Experimental modeling of chloride bearing diamond related liquids: a review.Goldschmidt Conference 2008, Abstract p.A817.Africa, Botswana, South America, Brazil, Russia, CanadaDiamond inclusions
DS1960-1190
1969
Perchuk, L.L.Perchuk, L.L., et al.Origin of Eclogite in the Kokchetav BlockDoklady Academy of Science USSR, Earth Science Section., Vol. 186, No. 1-6, PP. 161-163.RussiaKimberlite
DS1980-0280
1980
Perchuk, L.L.Perchuk, L.L., Vaganov, V.I.Petrochemical and Thermodynamic Evidence on the Origin of Kimberlites.Contributions to Mineralogy and Petrology, Vol. 72, PP. 219-228.South AfricaKimberlite Genesis
DS1984-0581
1984
Perchuk, L.L.Perchuk, L.L., Ryabichov, I.D.Experimental study of mechanism and rate of reaction Of kimberlite liquidwith inclusions. Search for liquidus and reaction at 12.5 kilobar pressure.Ocherki Fiz. Khim. Petrol., (Russian), Vol. 12, pp. 5-14RussiaInclusions
DS1991-1327
1991
Perchuk, L.L.Perchuk, L.L.Studies in magmatism, metamorphism and geodynamicsInternational Geology Review, Vol. 33, No. 4, April pp. 311-374GlobalMagma, Metamorphism
DS1991-1328
1991
Perchuk, L.L.Perchuk, L.L.Progress in metamorphic and magmatic petrologyCambridge University Press, 480pMantleGeobarometry, metamorphism, Metasomatism, Mantle, magmatism
DS1992-1182
1992
Perchuk, L.L.Perchuk, L.L., Gerya, T.V.The fluid regime of metamorphism and the charnockite reaction ingranulites: a reviewInternational Geology Review, Vol. 34, No. 1, January pp. 1-58RussiaGranulites -review, metamorphism
DS1992-1183
1992
Perchuk, L.L.Perchuk, L.L., Podladchikov, Y.Yu., Polyakov, A.N.Hydrodynamic modelling of some metamorphic processesJournal of Metamorphic Geology, Vol. 10, No. 3, May pp. 311-320GlobalMetamorphic processes, Modelling
DS1993-0122
1993
Perchuk, L.L.Bindeman, I.N., Perchuk, L.L.Experimental studies of magma mixingInternational Geology Review, Vol. 35, No. 8, August pp. 721-738Russia, Commonwealth of Independent States (CIS)Magma, Convective mixing -experimental
DS1995-1479
1995
Perchuk, L.L.Perchuk, L.L., Yapaskurt, V.O., Okay, A.Comparative petrology of diamond bearing complexesPetrology, Vol. 3, No. 3, May-June pp. 238-277.RussiaPetrology, Diamond complexes
DS1996-1108
1996
Perchuk, L.L.Perchuk, L.L., Gerya, T.V., Van Reenen, D.D., Safonov, SmitThe Limpopo metamorphic belt, South Africa: decompression and cooling regimes of granulites...Petrology, Vol. 4, No. 6, Nov-Dec. pp. 571-599.South AfricaCraton - Kaapvaal, Limpopo metamorphic belt
DS2000-0754
2000
Perchuk, L.L.Perchuk, L.L., Gerya, T.V., Krotov, A.V.P-T paths and tectonic evolution of shear zones separating high grade terrains from cratons:Min. Petrol., Vol. 69, No. 1-2, pp. 109-42.South Africa, Russia, Kola PeninsulaHigh grade terrains - comparison, Tectonics - Kola and Limpopo
DS2000-0755
2000
Perchuk, L.L.Perchuk, L.L., Gerya, T.V., Yu.M.Comparative petrology and metamorphic evolution of the Limpopo (South Africa) and Lapland ( Fennoscandia)...Min. Petrol., Vol. 69, No. 1-2, pp. 69-108.South Africa, Scandinavia, LaplandHigh grade terrains - comparison, Petrology, metamorphism
DS2001-0905
2001
Perchuk, L.L.Perchuk, L.L.Fluids in the lower crust and upper mantle of the EarthMoscow University of Geol. Bulletin., Vol. 55, No. 4, pp. 14-27.MantleGeochemistry - fluids
DS2002-0157
2002
Perchuk, L.L.Bindi, L., Safonov, O.G., Litvin, Y.A., Perchuk, L.L., Menchetti, S.Ultrahigh potassium content in the clinopyroxene structure: an x-ray single crystal studyEuropean Journal of Mineralogy, Vol. 14, 5, pp. 929-34.GlobalMineralogy - not specific to diamond
DS2002-0556
2002
Perchuk, L.L.Gerya, T.V., Perchuk, L.L., Maresch, W.V., Willner, A.P., Van ReenenThermal regime and gravitational instability of multi layered continental crust:European Journal of Mineralogy, Vol. 14,4,pp. 687-700.MantleUHP - not specific to diamonds
DS2002-1013
2002
Perchuk, L.L.Matveev, Y.A., Litvin, Y.A., Perchuk, L.L.Melting equilibration temperatures of the CaMgSiO3 Mg3Al2Si3O12 K2 Ca (Co2) system modelling a source composition of carbonate - silicate diamond bearing rocks Kokchetav18th. International Mineralogical Association Sept. 1-6, Edinburgh, abstract p.242. (poster)RussiaMineralogy - melting
DS2002-1243
2002
Perchuk, L.L.Perchuk, L.L., Safonov, O.G., Yapaskurt, BartonCrystal melt equilibration temperatures involving potassium bearing clinopyroxene as indicator of mantle derived ultrahighLithos, Vol.60, pp. 89-111.MantleMelting - potassic liquids, an analytical review
DS2002-1244
2002
Perchuk, L.L.Perchuk, L.L., Safonov, O.G., Yapaskurt, V.O., BartonCrystal melt equilibration temperatures involving potassium bearing clinopyroxene as indicator of mantle derived ultrahighLithos, Vol. 60, No. 3-4, Feb. pp. 89-111.MantleAnalytical review - potassic liquids
DS2002-1379
2002
Perchuk, L.L.Safonov, O.G., Malveev, Yu.A., Litvin, Y.A., Perchuk, L.L., Bindi, L., MenchettiUltrahigh pressure study of potassium bearing clinopyroxene equilibria18th. International Mineralogical Association Sept. 1-6, Edinburgh, abstract p.74.Russia, YakutiaUHP, mineralogy, Kokchteav Complex, kimberlites
DS2003-0111
2003
Perchuk, L.L.Bindi, L., Safonov, O.G., Yapaskurt, V.O., Perchuk, L.L., Menchetti, S.Ultrapotassic clinopyroxene from the Kumdy Kol microdiamond mine, KokchetavAmerican Mineralogist, Vol. 88, 2-3, Feb.March pp. 464-8.Russia, KazakhstanMineral chemistry, Kokchetav Complex
DS200512-0840
2004
Perchuk, L.L.Perchuk, L.L.Gravitational redistribution of rocks within the Precambrian continental crust: problem solution.Moscow University Geology Bulletin, Vol. 59, 5, pp. 19-31.RussiaGeodynamics, tectonics
DS200512-0925
2005
Perchuk, L.L.Safonov, O.G., Perchuk, L.L., Litrvin, Y.A., Bindi, L.Phase relations in the Ca Mg Si2O6 K Al Si308 join at 6 and s.5 GPa as a model for formation of some potassium bearing deep seated mineral assemblages.Contributions to Mineralogy and Petrology, Vol. 149, 3, pp. 316-337.Experimental petrology
DS200612-1199
2005
Perchuk, L.L.Safonov, O.G., Perchuk, L.L., Litvin, Y.A.Equilibrium K bearing clinopyroxene melt as a model for barometry of mantle derived mineral assemblages.Russian Geology and Geophysics, Vol. 46, 12, pp. 1300-1316.TechnologyGeobarometry
DS200712-0925
2006
Perchuk, L.L.Safonov, O.G., Perchuk, L.L., Litvin, Y.A.Melting relations in the chloride carbonate silicate systems at high pressure and model for formation of alkalic diamond forming liquids in the upper mantle.Earth and Planetary Science Letters, in press availableTechnologyUHP, melts, kimberlites
DS200912-0579
2009
Perchuk, L.L.Perchuk, L.L., Safonov, O.G.Carbonatite to kimberlite link in the chloride carbonate silicate system.Goldschmidt Conference 2009, p. A1012 Abstract.MantleGenesis
DS200912-0658
2009
Perchuk, L.L.Safonov, O.G., Perchuk, L.L., Yapaskurt, V.O., Litvin, Yu.A.Immiscibility of carbonate silicate and chloride carbonate melts in the kimberlite CaCO3 Na2Co3 KCL system at 4.8 GPa.Doklady Earth Sciences, Vol. 424, 1, pp. 142-146.TechnologyGeochemistry
DS201012-0649
2009
Perchuk, L.L.Safonov, O.G., Chertkova, L.L., Perchuk, L.L., Litvin, Yu.A.Experimental model for alkalic chloride rich liquids in the upper mantle.Lithos, Vol. 112 S pp. 260-273.MantleAlkaline rocks, chemistry
DS201012-0718
2010
Perchuk, L.L.Sizova, E., Gerya, T., Brown, M., Perchuk, L.L.Subduction styles in the Precambrian: insight from numerical experiments.Lithos, Available in press, formatted 21p.MantleSubduction, tectonics
DS201112-0900
2011
Perchuk, L.L.Safonov, O.G., Kamenetsky, V.S., Perchuk, L.L.Links between carbonatite and kimberlite melts in chloride-carbonate-silicate systems: experiments and application to natural assemblages.Journal of Petrology, Vol. 52, 7-8, pp. 1307-1331.TechnologyMelting
DS1990-0486
1990
Percival, J.Fountain, D.M., Percival, J., Salisbury, M.H.Exposed cross sections of the continental crust- synopsisExposed cross sections of the Continental Crust, ed. M.H. Salisbury and, pp. 653-662GlobalCrust, Geophysics
DS1990-0487
1990
Percival, J.Fountain, D.M., Salisbury, M.H., Percival, J.Seismic structure of the continental crust based on rock velocity measurements from the Kapuskasing UpliftJournal of Geophysical Research, Vol. 95, No. B2, February 10, pp. 1167-1186OntarioGeophysics -seismics, Kapuskasing Zone
DS1992-0993
1992
Percival, J.Maraschal, M., Fyfe, W.S., Percival, J., Chan, T.Grain-boundary graphite in Kapuskasing gneisses and implications for lower-crustal conductivityNature, Vol. 357, No. 6380, June 25, pp. 674-676OntarioGeophysics, Kapuskasing uplift
DS1992-0996
1992
Percival, J.Mareschal, M., Fyfe, W.S., Percival, J., Chan, T.Grain boundary graphite in Kapuskasing gneisses and implications for lower-crustal conductivityNature, Vol. 357, No. 6380, June 25, pp. 674-676OntarioRifting, Geophysics -conductivity
DS1998-0177
1998
Percival, J.Buchan, K.L., Mortensen, J.K., Card, K.D., Percival, J.Paleomagnetism and uranium-lead (U-Pb) geochronology of diabase dyke swarms of Minto Block Superior Province, Quebec.Canadian Journal of Earth Sciences, Vol. 35, No. 9, Sept. pp. 1954-69.QuebecDike swarms, Minto Block
DS2001-0667
2001
Percival, J.Leclair, A.D., Berclaz, David, Percival, J.Regional geological setting of Archean rocks in the northeastern Superior Province.Geological Association of Canada (GAC) Annual Meeting Abstracts, Vol. 26, p.84.abstract.Quebec, UngavaGeology - brief overview
DS2003-1062
2003
Percival, J.Percival, J.Superior Province: a billion year record of Archean craton evolution and the birth ofUniversity of Toronto Seminar talk, Jan 16, 2p. abstractOntario, Manitoba, QuebecCraton, Tectonics
DS200412-1523
2004
Percival, J.Percival, J.Superior Province: a billion year record of Archean craton evolution and the birth of plate tectonic processes.Geological Association of Canada, CD www.gac.ca/bookstoreCanada, Ontario, Manitoba, Alberta, Northwest TerritoriesCraton, tectonics
DS200812-0871
2008
Percival, J.Pease, V., Percival, J., Smithies, H., Stevens, G., Van Kramendonk, M.When did plate tectonics begin? Evidence from the orogenic record.Geological Society of America Special Paper, 440, pp. 199-228.MantleTectonics
DS201012-0605
2010
Percival, J.Pysklywec, R.N., Gogus, O., Percival, J., Cruden, A.R.Insights from geodynamical modeling on possible fates of continental mantle lithosphere: collision, removal, and overturn.Canadian Journal of Earth Sciences, Vol. 47, 4, pp. 541-563,MantleGeodynamics
DS1983-0511
1983
Percival, J.A.Percival, J.A., Krogh, T.E.uranium-lead (U-Pb) zircon geochronology of the Kapuskasing structural zone and vicinity on the Chapleau Foleyet area.Canadian Journal of Earth Sciences, Vol. 20, pp. 83043.OntarioTectonics - Structure, Ksz
DS1986-0638
1986
Percival, J.A.Percival, J.A., McGrath, P.H.Deep crustal structure and tectonic history of the northernKapuskasing uplift of Ontario and integrated petrological geophysical studyTectonics, Vol. 5, No. 4, August pp. 553-572OntarioTectonics
DS1987-0575
1987
Percival, J.A.Percival, J.A.The Kapuskasing uplift: Archean greenstones and granulitesInstitute Lake Superior Geology Field trip Guidebook, Vol. 33, pt. 5, 54pOntarioCanada, Tectonics
DS1989-0536
1989
Percival, J.A.Green, A.G., Milkereit, B., Davidson, A., Percival, J.A., ParrishReflection seismic profiling of the Kapuskasing structural zone, SOURCE[ Geological Association of Canada (GAC) Annual Meeting Program AbstractsGeological Society of Canada (GSC) Forum 1989, P. 11. abstractOntarioMidcontinent, Kapuskasing structure
DS1989-0537
1989
Percival, J.A.Green, A.G., Milkereit, B., Percival, J.A., Kurtz, R.D., BroomeIntegrated geophysical lithoprobe studies of the Kapuskasing structureGeological Society of Canada (GSC) Forum 1989, P. 11. abstractOntarioGeophysics, Kapuskasing
DS1989-1194
1989
Percival, J.A.Percival, J.A.Metamorphism and melting at an exposed example of theConraddiscontinuity, Kapuskasing uplift, CanadaFluid movements-element transport and the composition of the deep, Vol. 281, pp. 51-60OntarioKapuskasing rift zone, Conrad discontinuity
DS1989-1195
1989
Percival, J.A.Percival, J.A.A regional perspective of the Quetico metasedimentary belt, Superiorprovince, CanadaCanadian Journal of Earth Sciences, Vol. 26, No. 4, April pp. 677-693OntarioQuetico Belt, Tectonics
DS1989-1196
1989
Percival, J.A.Percival, J.A.The Kapuskasing uplift: a window on the deep crust Of the SuperiorprovinceGeological Association of Canada (GAC) Annual Meeting Program Abstracts, Vol. 14, p. A102. (abstract.)OntarioTectonics, Kapuskasing Lithoprobe
DS1989-1197
1989
Percival, J.A.Percival, J.A., Green, A.G.Lithoprobe studies of the Kapuskasing uplift: an exposed crustal crosssectionGeological Society of Canada (GSC) Forum 1989, P. 19 abstractOntarioMidcontinent
DS1989-1198
1989
Percival, J.A.Percival, J.A., Green, A.G., Milkereit, B., Cook, F.A., Geis, W.Seismic reflection profiles across deep continental crust exposed in the Kapuskasing uplift structureNature, Vol. 342, No. 6248, November 23, pp. 416-419OntarioGeophysics -seismic, Kapuskasing rift zone
DS1990-0527
1990
Percival, J.A.Geis, W.T., Cook, F.A., Green, A.G., Milkereit, B., Percival, J.A.Thin thrust sheet formation of the Kapuskasing structural zone revealed bylithoprobe seismic reflection dataGeology, Vol. 18, No. 6, June pp. 513-516OntarioGeophysics -Seismics, Kapuskasing Zone
DS1990-0528
1990
Percival, J.A.Geis, W.T., Cook, F.A., Green, A.G., Milkereit, B., Percival, J.A.Thin thrust sheet formation of the Kapuskasing structural zone revealed by lithoprobe seismic reflection dataGeology, Vol. 18, No. 6, June pp. 513-516OntarioGeophysics, Kapuskasing Zone
DS1990-1045
1990
Percival, J.A.Milkereit, B., White, D., Percival, J.A., Vasudevan, K., ThurstonHigh resolution seismic reflection profiles across the Kapuskasing structure #1G.s.c. Forum January 16-17, Ottawa, Poster display AbstractOntarioGeophysics, Seismics
DS1990-1172
1990
Percival, J.A.Percival, J.A.Evolution of the lower continental crustTerra, Abstracts of Crustal Dynamics: Pathways and Records held Bochum FRG, Vol. 2, December p. 47OntarioGeophysics, Kapuskasing tectonics
DS1990-1173
1990
Percival, J.A.Percival, J.A.A field guide to the Kapuskasing uplift, a cross section through the Archean Superior ProvinceExposed Cross Sections of the Continental Crust; ed. M.H. Salisbury, D.M., Vol. 317, pp. 227-283OntarioTectonics, Kapuskasing uplift
DS1991-0969
1991
Percival, J.A.Leclair, A.D., Percival, J.A., Milkereit, B., Green, A.G., West G.F.Seismic reflection profiles across major faults of the central KapuskasingUpliftGeological Association of Canada (GAC)/Mineralogical Association of Canada/Society Economic, Vol. 16, Abstract program p. A73OntarioTectonics, Geophysics -seismics
DS1991-1132
1991
Percival, J.A.Mereu, R.F., Percival, J.A., Mareschal, M., Salisbury, M.H.Collaborative special project to identify seismic reflectors in high grade metamorphic rocks of the Kapuskasing UpliftCan. Cont. Drilling Project, August 40pOntarioGeophysics -seismics, Kapuskasing Zone
DS1991-1154
1991
Percival, J.A.Milkereit, B., Percival, J.A., White, D., Green, A.G., SalisburySeismic reflectors in high grade metamorphic rocks of the Kapuskasinguplift: results of preliminary drill site surveysGeodynamics, Vol. 22, pp. 39-45OntarioKapuskasing uplift, Geophysics -seismics
DS1991-1155
1991
Percival, J.A.Milkereit, B., White, D.J., Percival, J.A., Vasudevan, K., ThurstonHigh resolution seismic reflection profiles across the Kapuskasing structure #2Ontario Geological Survey Open File, Open File No. 5781, 37pOntarioGeophysics -seismics, Kapuskasing structural zone
DS1991-1329
1991
Percival, J.A.Percival, J.A., Bursnall, J.T., Moser, D.E., Shaw, D.M.Site survey for the Canadian Continental Drilling Program Pilot Project In the Kapuskasing UpliftOntario Geological Survey Open File, Open File No. 5790, 34pOntarioDrilling, Kapuskasing structural zone
DS1991-1330
1991
Percival, J.A.Percival, J.A., Bursnall, J.T., Moser, D.E., Shaw, D.M.Site survey for the Canadian Continental Drilling Program's Pilot Projectin the Kapuskasing UpliftOntario Geological Survey Open File, Open File No. 5790, 34pOntarioDrilling, Kapuskasing Structural Zone
DS1991-1331
1991
Percival, J.A.Percival, J.A., Moser, D.E.Crustal scale structure and evolution of the Abitibi Wawa subprovince:insights from the Kapuskasing upliftGeological Association of Canada (GAC)/Mineralogical Association of Canada/Society Economic, Vol. 16, Abstract program p. A97OntarioTectonics, Rifting
DS1991-1332
1991
Percival, J.A.Percival, J.A., Shaw, D.M., Milkereit, B., White, D.J., Jones, A.G.A closer look at deep crustal reflectionsEos, Vol. 72, No. 32, August 6, pp. 337, 339, 340, 341United States, CanadaTectonics, Geophysics -seismics
DS1992-0792
1992
Percival, J.A.Jianjun Wu, Mereu, R.F., Percival, J.A.Seismic image of the Ivan hoe Lake fault zone in the Kapuskasing uplift Of the Canadian shieldGeophysical Research Letters, Vol. 19, No. 4, February 21, pp. 353-360OntarioStructure -fault, Geophysics -seismics
DS1992-1654
1992
Percival, J.A.White, D.J., Milkereit, B., Salisbury, M.H., Percival, J.A.Crystalline lithology across the Kapuskasing Uplift determined using insitu Poisson's ratio from seismic tomography.Journal of Geophysical Research, Vol. 97, No. B13, December 10, pp. 19, 993-20, 006.OntarioGeophysics -seismics, Lithology, Kapuskasing uplift
DS1994-1010
1994
Percival, J.A.Leclair, A.D., Percival, J.A., Green, A.G., et al.Seismic reflection profiles across the central Kapuskasing upliftCanadian Journal of Earth Sciences, Vol. 31, No. 7, July pp. 1016-1026.OntarioGeophysics -seismics, Tectonics -Kapuskasing uplift
DS1994-1362
1994
Percival, J.A.Percival, J.A.Archean high grade metamorphismElsevier, Condie editor, Archean Crustal Evolution, pp. 357-410GlobalMetamorphism - concepts, Archean
DS1994-1363
1994
Percival, J.A.Percival, J.A., Palmer, H.C., Barnett, R.L.Quantitative estimates of emplacement level of post metamorphic mafic dykesand subsequent erosion...Canadian Journal of Earth Sciences, Vol. 31, No. 7, July pp. 1218-1226.OntarioGeodynamics, Tectonics -Kapuskasing uplift
DS1994-1364
1994
Percival, J.A.Percival, J.A., Peterman, Z.E.rubidium-strontium (Rb-Sr) biotite and whole rock dat a from the Kapuskasing uplift and their bearing on the cooling and exhumationCanadian Journal of Earth Sciences, Vol. 31, No. 7, July pp. 1172-1181.OntarioGeochronology, Tectonics -Kapuskasing uplift
DS1994-1365
1994
Percival, J.A.Percival, J.A., Stern, R.A., et al.Minto block, Superior Province: missing link in deciphering assembly of the craton at 2.7 Ga.Geology, Vol. 22, No. 9, September pp. 839-842.Quebec, Labrador, UngavaTectonics, geochronology, Minto Block, Vizien belt
DS1994-1366
1994
Percival, J.A.Percival, J.A., West, G.F.The Kapuskasing uplift: a geological and geophysical synthesisCanadian Journal of Earth Sciences, Vol. 31, No. 7, July pp. 1256-1286.OntarioGeology, geophysics, Tectonics -Kapuskasing uplift
DS1994-1689
1994
Percival, J.A.Stern, R.A., Percival, J.A., Mortensen, J.K.Geochemical evolution of the Minto Block: a 2.7 Ga continental magmatic arc built on the Superior proto-cratonPrecambrian Research, Vol. 65, No. 1-4, January pp. 115-154Canada, OntarioGeochemistry, Craton
DS1996-0847
1996
Percival, J.A.Lin, S., Percival, J.A., Skuliski, T.Structural constraints on the tectonic evolution of a late Archean greenstone belt in northeast Superior ProvinceTectonophysics, Vol. 265, No. 1/2, Nov. 15, pp. 151-168QuebecTectonics, Abitibi belt
DS1996-1109
1996
Percival, J.A.Percival, J.A.Archean cratonsGeological Survey of Canada, LeCheminant ed, OF 3228, pp. 11-16.Canada, GlobalCraton -Archean
DS1996-1324
1996
Percival, J.A.Skulski, T., Percival, J.A.Allochthonous 2.78 Ga oceanic plateau slivers in a 2.72 Ga continental arcsequence... Vizien GS, Superior ProvLithos, Vol. 37, No. 2/3, April pp. 163-180OntarioContinental arc sequence, Vizien greenstone belt
DS1999-0298
1999
Percival, J.A.Hattori, K., Percival, J.A.Archean carbonate bearing alkaline igneous complexes of the western Queticometa sedimentary belt Superior ProvinceGeological Survey of Canada (GSC), Current Research 1999- C, pp. 221-232.OntarioAlkaline rocks
DS1999-0299
1999
Percival, J.A.Hattori, K.H., Percival, J.A.Carbonate bearing alkaline magmatism in the Quetico metasedimentary belt, Superior Province, Canada.Geological Association of Canada (GAC) Geological Association of Canada (GAC)/Mineralogical Association of Canada (MAC)., Vol. 24, p. 51. abstractOntarioAlkaline rocks, Magmatism
DS1999-0558
1999
Percival, J.A.Pilkington, M., Percival, J.A.Crustal magnetization and long wave aeromagnetic anomalies of the MintoBlock, Quebec.Journal of Geophysical Research, Vol. 104, No. 4, Apr. 10, pp. 7513-26.QuebecGeophysics - aeromagnetics, Minto Block - not specific to diamonds
DS2000-0756
2000
Percival, J.A.Percival, J.A., Skulski, T.Tectonothermal evolution of the northern Minto block, Superior Province, Quebec, Canada.Can. Mineralog., Vol. 38, No. 2, Apr. pp. 345-78.QuebecTectonics - metamorphism - Minto Block, Superior Province
DS2000-0757
2000
Percival, J.A.Percival, J.A., Skulski, T., Whalen, J.B., Theriault, R.Continental arc plutonism: major agent of crustal growthGeological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) 2000, 2p. abstract.Northwest Territories, Canadian ShieldTectonics - subduction
DS2001-0906
2001
Percival, J.A.Percival, J.A., Stern, R.A., Skulski, T.Crustal growth through successive arc magmatism: reconnaissance uranium-lead (U-Pb) SHRIMP dat a from northeast Superior ProvincePrecambrian Research, Vol. 109, No. 3-4, pp. 203-38.QuebecBienville subprovince, Minto block, Geochronology
DS2001-0924
2001
Percival, J.A.Pilkington, M., Percival, J.A.Relating crustal magnetization and satellite altitude magnetic anomalies in the Ungava peninsula, north. Que.Earth and Planetary Science Letters, Vol. 194, No. 1-2, pp. 127-33.Quebec, Ungava, LabradorGeophysics - magnetics - not specific to diamonds
DS2002-1245
2002
Percival, J.A.Percival, J.A.Tectonic evolution of the Superior Province, 3.0-2.6 GaUniversity of Western Ontario, SEG Student Chapter, March 8, pp. 1-4. abstractOntarioTectonics, Neoarchean magmatism
DS2002-1246
2002
Percival, J.A.Percival, J.A., Brown, M., Heaman, L., Hynes, A., Rivers, T., Skulski, T.Tectonic and magmatic processes in crustal growth: a pan lithospheric perspectiveGeoscience Canada, Vol. 29, 7, Sept. pp. 121-5.MantleMafic magmatism, accretionary tectonics, collision
DS2002-1247
2002
Percival, J.A.Percival, J.A., Brown, M., Heaman, L., Rivers, T., Skulski, T.Tectonic and magmatic processes in crustal growth: a pan-lithoprobe perspectiveGeoscience Canada, Vo. 29, No. 3, September pp. 121-5.Canada, MantleGeophysics - seismics, lithoprobe, rifting, arc, Accretion, collision
DS2003-1063
2003
Percival, J.A.Percival, J.A., Stern, R.A., Rayner, N.Archean adakites from the Ashuanipi complex, eastern Superior Province Canada:Contributions to Mineralogy and Petrology, Vol. 145, 3, pp. 265-80.OntarioBlank
DS2003-1472
2003
Percival, J.A.Whalen, J.B., Percival, J.A., McNicholl, V.J., Longstaffe, F.J.Intra oceanic production of continental crust in a Th depleted ca. 3.0 Ga arc complexContributions to Mineralogy and Petrology, Vol. 146, 1, pp. 78=99.Ontario, Manitoba, QuebecTectonics
DS200412-1524
2004
Percival, J.A.Percival, J.A., Bleeker, W., Cook, E.A., Rivers, T., Ross, G., Van Staal, C.PanLithoprobe Workshop IV: intra orogen correlations and comparative orogenic anatomy.Geoscience Canada, Vol. 31, 1, pp. 23-39.Canada, United StatesTectonics, Precambrian, geochronology, orogens
DS200412-1525
2003
Percival, J.A.Percival, J.A., Stern, R.A., Rayner, N.Archean adakites from the Ashuanipi complex, eastern Superior Province Canada: geochemistry, geochronology and tectonic significContributions to Mineralogy and Petrology, Vol. 145, 3, pp. 265-80.Canada, OntarioTectonics
DS200412-2107
2003
Percival, J.A.Whalen, J.B., Percival, J.A., McNicholl, V.J., Longstaffe, F.J.Intra oceanic production of continental crust in a Th depleted ca. 3.0 Ga arc complex, western Superior Province, Canada.Contributions to Mineralogy and Petrology, Vol. 146, 1, pp. 78=99.Canada, Ontario, Manitoba, QuebecTectonics
DS200512-0841
2005
Percival, J.A.Percival, J.A., Pysklywec, R.N.Archean lithospheric mantle inversion: key to diamond productivity of cratonic keels.GAC Annual Meeting Halifax May 15-19, Abstract 1p.MantleGeothermometry, Diamond evolution
DS200712-0831
2007
Percival, J.A.Percival, J.A.The dynamic Archean Earth.Plates, Plumes, and Paradigms, 1p. abstract p. A776.MantleGeodynamics
DS200712-0832
2007
Percival, J.A.Percival, J.A., Pysklywec, R.N.Are Archean lithospheric keels inverted?Earth and Planetary Science Letters, Vol. 254, 3-4, pp. 393-403.MantleGeodynamics, tectonics
DS201312-0699
2012
Percival, J.A.Percival, J.A., Cook, F.A., Clowes, R.M.Tectonic styles in Canada: the Lithoprobe.Geological Association of Canada Special Paper, No. 49, 498p. Approx $ 70.00 memberCanadaBook - Geophysics
DS201412-0142
2012
Percival, J.A.Cook, F.A., Percival, J.A., Clowes, R.M.Tectonic styles in Canada: lithoprobe perspectives on the evolution of the North American continent.Tectonic styles in Canada: the lithoprobe perspective, eds. Percival, Cook, Clowes, Geological Survey of Canada, Special Paper, 49, pp. 489-Canada, United StatesTectonics - lithoprobe
DS202203-0343
2022
Percival, J.B.Desbarats, A.J., Percival, J.B., Bilot, I., Polivchuk, M.J., Venance, K.E.Drainage geochemistry of mine tailings from a carbonatite-hosted Nb-REE deposit, Oka Quebec, Canada.Applied Geochemistry, Vol. 138, 14p. PdfCanada, Quebecdeposit - Oka

Abstract: Potential environmental issues associated with the mining of carbonatites are receiving increased attention due to the importance of critical metals for green technologies. This study investigates the chemistry of tailings seepage at the former Saint Lawrence Columbium mine near Oka, Québec, Canada, which produced pyrochlore concentrate and ferroniobium from a carbonatite-hosted Nb-REE deposit. Detailed field sampling and laboratory methods were used to characterize the hydraulic properties of the tailings, their bulk chemistry, mineralogy, pore water and effluent chemistries. The tailings are composed of REE-enriched calcite (64-89 wt %) and fluorapatite (2-22 wt %), as well as biotite (6-17 wt %) and chlorite (0-7 wt %). Minor minerals include ankerite, pyrite, sphalerite, molybdenite, magnetite and unrecovered pyrochlore. Secondary minerals include gypsum, barite, strontianite and rhodochrosite. Geochemical mass balance modeling, constrained by speciation modeling, was used to identify dissolution, precipitation and exchange reactions controlling the chemical evolution of pore water along its flow path through the tailings impoundment. In the unsaturated zone, these reactions include sulfide oxidation and calcite dissolution with acid neutralization. Below the water table, gypsum dissolution is followed by sulfate reduction and FeS precipitation driven by the oxidation of organic carbon in the tailings. Incongruent dissolution of biotite and chlorite releases K, Mg, Fe, Mn, Ba and F and forms kaolinite and Ca-smectite. Cation exchange reactions further remove Ca from solution, increasing concentrations of Na and K. Fluoride concentrations reach 23 mg/L and 8 mg/L in tailings pore water and effluent, respectively. These values exceed Canadian guidelines for the protection of aquatic life. In the mildly alkaline (pH 8.3) pore waters, Mo is highly mobile and reaches an average concentration of 83 ?g/L in tailings effluent, which slightly exceeds environmental guidelines. Concentrations (unfiltered) of Zn reach 1702 ?g/L in tailings pore water although values in effluent are usually less than 20 ?g/L. At the ambient pH, Zn is strongly adsorbed by Fe-Mn oxyhydroxides. Although U forms mobile complexes in tailings pore water, concentrations do not exceed 16 ?g/L due to the low solubility of its pyrochlore host. Adsorption and the low solubility of pyrochlore limit concentrations of Nb to less than 49 ?g/L. Cerium, from calcite dissolution, is strongly adsorbed although it reaches concentrations (unfiltered) in excess of 1 mg/L and 100 ?g/L in pore water and effluent, respectively. Results of this study show that mine tailings from carbonatite deposits are enriched in a wide variety of incompatible elements with multiple mineral hosts of varying solubility. Some of these elements, such as F and Mo, may represent contaminants of concern because of their mobility in alkaline tailings waters.
DS1995-1480
1995
Perdoncini, L.Perdoncini, L.Diamond occurrences related to glacial deposits in the Itare Group, ParanoBrasil.University of Parano, MSc. thesisBrazilGeomorphology, Thesis
DS1996-1110
1996
Perdoncini, L.Perdoncini, L.Diamond deposits associated with the glacial deposits of the Itar are Group.Parana Basin. *REF ONLY in Port.Msc. Thesis, University Of Fed. Do Parana, Curtiba, *ref Only, BrazilGeomorphology, Deposit -Itarare Group
DS1995-1481
1995
Perdoncini, L.C.Perdoncini, L.C., Soares, P.C., Bizzi, L.A.Diamonds associated with the Permo-Carboniferous glacial deposits in the Parana Basin, Brasil.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 436-438.Brazil, Parana, Paraguay, Uruguay, ArgentinaGeomorphology, Alluvials
DS1997-0900
1997
Perdoncini, L.C.Perdoncini, L.C.Diamond deposits associated with the glacial deposits of the Itar are Parana Basin.Msc Thesis Universidade Federal Do Parana, Please note notice onlyBrazil, ParanaSedimentology, glacial, alluvial, Deposit - Itarare Group
DS201112-0777
2010
Perdoncini, L.C.Perdoncini, L.C., Soares, P.C., Roberto de Gois, J.Excursao de acmpo: Geologia e ocxorencias diamantiferas da regiao de Tibagi.5th Brasilian Symposium on Diamond Geology, Nov. 6-12, Guidebook pp. 92-101.South America, Brazil, ParanaGuidebook area - Tibagi
DS1997-0178
1997
Perdue, E.M.Chameides, W.L., Perdue, E.M.Biogeochemical cycles: a computer interactive study of earth system science and global changeOxford University of Press, 256p. approx. $ 40.00 United StatesGlobalBook - ad, Biogeochemical cycles
DS1987-0162
1987
Peredery, W.V.Dressler, B.O., Morrison, G.G., Peredery, W.V., Rao, B.V.The Sudbury structure, Ontario, Canada- a ReviewBraunschweig Wiesbaden Vieweg, pp. 39-68OntarioSudbury, Impact structure
DS2002-1670
2002
Peregoudov, D.Vinnick, L., Peregoudov, D., Makeyeva, L., Oreshin, S., Roecker, S.Towards 3 D fabric in the continental lithosphere and asthenosphere: the Tien ShanGeophysical Research Letters, Vol. 16, 39, Aug. 15, 10.1029/2001GL014588ChinaGeophysics - seismics
DS200912-0687
2009
Peregovich, B.Sgarbi, G.B.C., Karfunkel, J., De Albuquerque Sgarbi, P.B., Peregovich, B., Da Silva, F.P., Dias, S., MooreThe Paredao kimberlite, western Minas Gerais, Brazil: field relations, chemical dat a and host rocks.Neues Jahrbuch fur Geologie und Palaontologie , Vol. 253, 1, July, pp. 115-131/South America, BrazilDeposit - Paredao
DS200712-0833
2006
Peregrine Diamonds Ltd.Peregrine Diamonds Ltd.Peregrine's interest in WO project increases to 71.74 %.Peregrine Diamonds Ltd., Dec. 13, 1p.Canada, Northwest TerritoriesNews item - press release, Kettle River
DS201112-0264
2011
PerehoginDenison, V.N., Mavrin, Serebryanaya, Dubitsky, Aksenenkov, Kirichenko, Kuzmin, kulnitsky, PerehoginFirst priniples, UV Raman, X-ray diffraction and TEM study of the structure and lattic dynamics of the diamond lonsdaleite system.Diamond and Related Materials, Vol. 20, 7, pp. 951-953.TechnologyLonsdaleite
DS201412-0274
2014
Pereira, A.Garzanti, E., Resentini, A., Ando, S., Vezzoli, G., Pereira, A., Vermeesch, P.Physical controls on sand and composition and relative durability of detrital minerals during ultra-long distance littoral and aeolian transport ( Namibia and southern Angola).Sedimentology, Vol. 62, 4, pp. 971-996.Africa, Namibia, AngolaDiamondiferous littoral deposits
DS1997-0901
1997
Pereira, C.P.G.Pereira, C.P.G., Walsh, D.G.Current researchNewfoundland Department of Mines, Report 97-1, 300pNewfoundland, LabradorBook - table of contents, Metallogeny, deposits
DS1997-0902
1997
Pereira, C.P.G.Pereira, C.P.G., Walsh, D.G.Current research - Mokami Hill, Hunt River, Nain, magmatic deposits, greenstone belts...Newfoundland, Department of Mines and Energy, Report 97-1, 300pNewfoundland, LabradorBook - table of contents, Review of activities, nickel
DS1987-0576
1987
Pereira, E.Pereira, E., Santos, L.Long lived red luminesence in diamondJournal of Luminescence, Vol. 38, No. 10*-6, Dec. 1, pp. 181-183GlobalBlank
DS1988-0539
1988
Pereira, E.Pereira, E., Santos, L.Brown diamonds - long lived visible luminescing centersJournal of Luminesc, Vol. 40, No. 1, February pp. 139-140GlobalBlank
DS1991-1333
1991
Pereira, E.Pereira, E., Monteiro, T.Delayed luminescence of the H-3 center in diamondJournal of Luminesence, Vol. 48-9, Jan.-Feb., pp. 814-818GlobalLuminesence, Diamond -H-3 center
DS201312-0249
2013
Pereira, E.Ernst, R.E., Pereira, E., Hamilton, M.A., Pisarevsky, S.A., Rodriques, J., Tasinari, C.C.G., Teixeira, W., Van-Dunem, V.Mesoproterozoic intraplate magmatic 'barcode' record of the Angola portion of the Congo craton: newly dated magmatic events at 1505 and 1110 Ma and implications for Nuna ( Columbia) supercontinent reconstructions.Precambrian Research, Vol. 230, pp. 103-118.Africa, AngolaMagmatism
DS2001-0907
2001
Pereira, F.Pereira, F., Bilal, E., Moutte, Lapido, Gruffat, AlbertDissolution of apatite ore from Angico Dos Dias carbonatite Complex and recovery of rare earth elementsJournal of South African Earth Sciences, Vol. 32, No. 1, p. A 28.(abs)BrazilCarbonatite, Angico Dos Dias
DS200812-0840
2008
Pereira, G.S.B.Palmieri, M., Pereira, G.S.B., Brod, J.A., Junquiera-Brod, T.C., Petrinovic, I.A., Ferrari, A.J.D.Orbicular magnetite from the Catalao I phoscorite carbonatite complex.9IKC.com, 3p. extended abstractSouth America, BrazilCarbonatite
DS201906-1334
2019
Pereira, L.Pereira, L., Birtel, S., Mockel, R., Michaux, B., Silva, A.C.Constraining the economic potential of by-product recovery by using a geometallurgical approach: the example of rare earth element recovery at Catalao 1, Brazil.Economic Geology, Apr. 15. abstractSouth America, Brazildeposit - Catalao 1

Abstract: Geometallurgy aims to develop and deploy predictive spatial models based on tangible and quantitative resource characteristics that are used to optimize the efficiency of minerals beneficiation and extractive metallurgy operations. Whilst most current applications of geometallurgy are focused on the major commodity to be recovered from a mineral deposit, this contribution delineates the opportunity to use a geometallurgical approach to provide an early assessment of the economic potential of by-product recovery from an ongoing mining operation. As a case study for this methodology possible REE-recovery as a by-product of Nb-production at the Catalão I carbonatite complex, the Chapadão mine is used. Catalão I is part of the Alto Paranaíba Igneous Province in the Goias Province of Brazil. Nowadays, niobium is produced in the complex as a by-product of the Chapadão phosphates mine. This production is performed on the Tailings plant, the focus of this study. Rare earth elements, albeit present in significant concentrations, are currently not recovered as by-products. Nine samples from different stages of the Nb beneficiation process in the Tailings plant were taken and characterized by Mineral Liberation Analyzer, X-ray powder diffraction, and bulk rock chemistry. The recovery of rare earth elements in each of the tailing streams was quantified by mass balance. The quantitative mineralogical and microstructural data are used to identify the most suitable approach to recover REE as a by-product-without placing limitations on niobium production. Monazite, the most common rare earth mineral identified in the feed, occurs as Ce-rich and La-rich varieties that can be easily distinguished by SEM-based image analysis. Quartz, FeTi-oxides and several phosphate minerals are the main gangue minerals. The highest rare earth oxide content concentrations (1.75 wt.% TREO) and the greatest potential for REE processing are reported for the final flotation tailings stream. To place tentative economic constraints on REE recovery from the tailings material, an analogy to the Browns Range deposit in Australia is drawn. Its technical flow sheet was used to estimate the cost for a hypothetical REE-production at Chapadão. Parameters derived from SEM-based image analysis were used to model possible monazite recovery and concentrate grades. This exercise illustrates that a marketable REE concentrate could be obtained at Chapadão if the process recovers at least 53 % of the particles with no less than 60% of monazite on their surface. Applying CAPEX and OPEX values similar to that of Browns Range suggest that such an operation would be profitable at current REE prices.
DS1984-0582
1984
Pereira, M.Pereira, M., Estela, J.M., Isabel, B., Thomaz, M.F.Slow Transitions in Diamond: the Photoluminescence S//1 Centre.Journal of LUMINESCENCE., Vol. 31-32, PT. 1-2, Dec. PP. 179-181.GlobalExperimental Research
DS1986-0639
1986
Pereira, M.E.Pereira, M.E., Jorge, M.I.B., Thomaz, M.F.The red luminescence spectrum of brown diamonds- vibronic couplingJournal of Phys. C., Vol. 19, No. 7, March 10, pp. 1009-1015GlobalDiamond morphology
DS1987-0577
1987
Pereira, M.E.Pereira, M.E., Barradas, M.I., Thomaz, M.F.The optical S1 centre in diamond-vibronic coupling and lifetimeJournal of Phys. C., Vol. 20, No. 30, October 30, pp. 4923-932GlobalBlank
DS1987-0578
1987
Pereira, M.E.Pereira, M.E., Barradas, M.I., Thomz, M.F.The optical S1 center in diamond: vibronic coupling and lifetimeJournal of Physics C.: Solid State Physics, Vol. 20, No. 30, pp. 4923-4932GlobalBlank
DS200512-0842
2004
Pereira, P.Pereira, P., Wyatt, B., Scott Smith, B., Letendre, J.Retrospective of diamond exploration at the Hardy Lake property, Lac de Gras region, Northwest Territories, Canada.32nd Yellowknife Geoscience Forum, Nov. 16-18, p.60-61. (talk)Canada, Northwest TerritoriesGeochemistry, geophysics, petrology
DS201907-1567
2017
Pereira, R.G.Pereira, R.G., Fuck, R.A., Franca, O.S., Leite, A.A.Evidence of young, proximal and primary ( YPP) diamond source occurring in alluviums in the Sant Antonio do Bonito, Santo Inacio and Dourahinho rivers in the Coromandel region, Minas Gerais.Brazil Journal of Geology, Vol. 47, 3, pp. 383-401. pdfSouth America, Brazilkimberlites, kamafugites, Tres Ranchos, Coromandel

Abstract: Magmatism associated with the Alto Paranaíba structural high comprises kimberlites, kamafugites, and alkaline complexes, forming an approximately 400 x 150 km NW-SE belt in the southern São Francisco Craton. Dating of some intrusions reveals ages between 120 and 75 Ma. Chemical analyses of garnet recovered in alluvium from traditional diamond digging areas indicate peridotitic garnet windows in Três Ranchos and Coromandel. Six hundred and eighty (680) diamonds acquired or recovered during mineral exploration in the digging areas of Romaria, Estrela do Sul, Três Ranchos and Coromandel show unique characteristics, certain populations indicating young, proximal and primary sources (YPP). Analyses of 201 stones from Santo Antônio do Bonito, Santo Inácio and Douradinho rivers alluvium, Coromandel, present no evidence of transport, characterizing a proximal source. Within these river basins, exposures of the Late Cretaceous Capacete Formation basal conglomerate contain mainly small rounded and/or angular quartzite pebbles and of basic and ultrabasic rocks, as well as kimberlite minerals (garnet, ilmenite, spinel, sometimes diamond). A magnetotelluric profile between the Paraná and Sanfranciscana basins shows that the thick underlying lithosphere in the Coromandel region coincides with the peridotitic garnet window and with a diamond population displaying proximal source characteristics. Diamond-bearing kimberlite intrusions occur in different areas of Alto Paranaíba.
DS201112-0778
2010
Pereira, R.M.Pereira, R.M.Deteccao de corpos kimberliticos a partir a coleta de pequenos volumes de material.5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 66-67.South America, Brazil, Minas GeraisDeposit - Canca
DS1998-1152
1998
Pereira, R.S.Pereira, R.S., Wheelock, G., Bizzi, L., Silva, LeiteAlluvial diamond potential of Paleo drainage systems in the headwaters Of the Sao Francisco River, Minas Gerais7th. Kimberlite Conference abstract, pp. 684-6.Brazil, Minas GeraisAlluvials, Deposit - Sao Francisco
DS201112-0779
2010
Pereira, R.S.Pereira, R.S.Aplicacao e resultados dos methodos de prospeccao para kimberlito e lamproito no craton do Sao Francisco. Techniques used and lineament map of area.5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 15-16.South America, BrazilBrief review of techniques
DS201412-0673
2014
Pereira, R.S.Pereira, R.S.Kimberlito- rocha relacionada e diamante no craton Amazonas. 6 Simposio Brasileiro de Geologia do Diamante, Aug. 3-7, 4p. AbstractSouth America, BrazilSao Francisco area
DS201712-2716
2017
Pereira, R.S.Pereira, R.S., Fuck, R.A., Soares Franca, O., Leite, A.A.Evidence of young, proximal and primary (YPP) diamond source occurring in alluviums in the Santa Antonio do Bonito, Santo Inacio and Douradhinho rivers in Coromandel region, Minas Gerais.Brazilian Journal of Geology, Vol. 47, 3, pp. 383-401.South America, Brazildeposit - Alta Paranaiba

Abstract: Magmatism associated with the Alto Paranaíba structural high comprises kimberlites, kamafugites, and alkaline complexes, forming an approximately 400 x 150 km NW-SE belt in the southern São Francisco Craton. Dating of some intrusions reveals ages between 120 and 75 Ma. Chemical analyses of garnet recovered in alluvium from traditional diamond digging areas indicate peridotitic garnet windows in Três Ranchos and Coromandel. Six hundred and eighty (680) diamonds acquired or recovered during mineral exploration in the digging areas of Romaria, Estrela do Sul, Três Ranchos and Coromandel show unique characteristics, certain populations indicating young, proximal and primary sources (YPP). Analyses of 201 stones from Santo Antônio do Bonito, Santo Inácio and Douradinho rivers alluvium, Coromandel, present no evidence of transport, characterizing a proximal source. Within these river basins, exposures of the Late Cretaceous Capacete Formation basal conglomerate contain mainly small rounded and/or angular quartzite pebbles and of basic and ultrabasic rocks, as well as kimberlite minerals (garnet, ilmenite, spinel, sometimes diamond). A magnetotelluric profile between the Paraná and Sanfranciscana basins shows that the thick underlying lithosphere in the Coromandel region coincides with the peridotitic garnet window and with a diamond population displaying proximal source characteristics. Diamond-bearing kimberlite intrusions occur in different areas of Alto Paranaíba.
DS201904-0770
2019
Pereira, S.Y.Raposo, D.B., Pereira, S.Y.Hydrochemistry and isotopic studies of carbonatite groundwater systems: the alkaline-carbonatite complex of Barreiro, southeastern Brazil.Environmental Earth Sciences, Vol. 78, pp. 233-South America, Brazilcarbonatite

Abstract: In Brazil, alkaline intrusions are source rocks for several commodities (bauxite, phosphate, niobium and barite, to mention a few), including mineral water. The present study aims to understand by means of chemical and stable isotope analyses, the residence time, circulation and hydrochemical facies of the groundwater systems from the alkaline-carbonatitic complex of Barreiro (State of Minas Gerais, Brazil). This Mesozoic alkaline complex is located in the Brazilian tropical region characterized by weathered soils and fractured rocks, which play an important role in the groundwater dynamics. To assess this influence, groundwater samples from 12 points and water samples from 3 artificial lakes were collected for the determination of chemical element and natural isotope (18O, deuterium and 13C) concentrations and 14C and tritium dating. Two main groundwater categories were revealed: (a) a local, acidic and sub-modern groundwater system developed in thick, poorly mineralized weathered soil from the inner part of ACCB, and (b) a basic, hypothermal, ca. 40-ky-old fractured aquifer developed in mineralized fenitized quartzites. The younger and shallower groundwater circulation is controlled by the present intrusion relief and is prone to environmental impacts. The older, hypothermal groundwater system indicates existing geothermal residual heat provided by the Mesozoic alkaline intrusion.
DS1995-1482
1995
Pereira, V.P.Pereira, V.P.Weathering of alkaline rocks at Catalao 1, Goias, niobium, titanium and rare earth element (REE) behaviour.(in Portugese).Ph.d. Thesis, University of Fed. Rio Grande Do Sul, (in Portugese)., BrazilAlkaline rocks, Deposit -Catalao 1
DS1995-1483
1995
Pereira, V.P.Pereira, V.P.Weathering of alkaline rocks at Catalao I Goias. Niobium, titanium and rare earth elements (REE) behaviour.University of de Poitiers, Ph.d. thesisBrazilCarbonatite, Thesis
DS201712-2725
2017
Pereira, V.P.Rossoni, M.B., Bastos Neto, A.C., Souza, V.S., Marquea, J.C., Dantas, E., Botelho, N.F., Giovannini, A.L., Pereira, V.P.U-Pb zircon geochronological investigation on the Morro dos Seis Lagos carbonatite complex and associated Nb deposit ( Amazonas, Brazil).Journal of South American Earth Sciences, Vol. 80, pp. 1-17.South America, Brazilcarbonatite

Abstract: We present results of U-Pb dating (by MC-ICP-MS) of zircons from samples that cover all of the known lithotypes in the Seis Lagos Carbonatite Complex and associated lateritic mineralization (the Morro dos Seis Lagos Nb deposit). The host rock (gneiss) yielded an age of 1828 ± 09 Ma interpreted as the crystallization time of this unit. The altered feldspar vein in the same gneiss yielded an age of 1839 ± 29 Ma. Carbonatite samples provided 3 groups of ages. The first group comprises inherited zircons with ages compatible with the gneissic host rock: 1819 ± 10 Ma (superior intercept), 1826 ± 5 Ma (concordant age), and 1812 ± 27 Ma (superior intercept), all from the Orosirian. The second and the third group of ages are from the same carbonatite sample: the superior intercept age of 1525 ± 21 Ma (MSWD ¼ 0.77) and the superior intercept age of 1328 ± 58 Ma (MSWD ¼ 1.4). The mineralogical study indicates that the ~1.3 Ga zircons have affinity with carbonatite. It is, however, a tendence rather than a well-defined result. The data allow state that the age of 1328 ± 58 Ma represents the maximum age of the carbonatite. Without the same certainty, we consider that the data suggest that this age may be the carbonatite age, whose emplacement would have been related to the evolution of the K'Mudku belt. The best age obtained in laterite samples (a superior intercept age of 1828 ± 12 Ma) is considered the age of the main source for the inherited zircons related to the gneissic host rock.
DS202004-0516
2020
Pereira, V.P.Giovannini, A.L., Mitchell, R.H., Bastos Neto, A.C., Moura, C.A.V., Pereira, V.P., Porto, C.G.Mineralogy and geochemistry of the Morro dos Seis Lagos siderite carbonatite, Amazonas, Brazil.Lithos, vol. 360-361, 105433 20p. PdfSouth America, Brazil, Amazonascarbonatite

Abstract: The Morro dos Seis Lagos niobium rare earth element, Ti-bearing lateritic deposit (Amazonas, Brazil) is derived from a primary siderite carbonatite. The complex is the only example of a Nb deposit in which Nb-rich rutile is the main Nb ore mineral. Apart from the laterites, at the current level of exposure the complex consists only of siderite carbonatite; silicate rocks are absent. Three types of siderite carbonatite are recognized: (1) a brecciated and oxidized core siderite carbonatite consisting of up to 95 vol% siderite together with: hematite; pyrochlore; Nb-brookite; Ti-maghemite; and thorobastnäsite; (2) a REE- and P-rich variety of the core siderite carbonatite consisting of siderite (up to 95 vol%), hematite, minor pyrochlore, monazite and bastnäsite; (3) a border hydrothermal siderite carbonatite with ~70 vol% siderite, barite (~15 vol%), gorceixite (~7 vol%) and minor rhabdophane and pyrochlore. The country rock gneiss in which the carbonatite was emplaced was affected by potassic fenitization, with the formation of phlogopite and orthoclase together with monazite, fluorapatite and bastnäsite. The siderite carbonatites exhibit a wide variation of ?13C (?5.39‰ to ?1.40‰), accompanied by a significant variation in ?18O (17.13‰ to 31.33‰), especially in the REE-rich core siderite carbonatite, and are explained as due to the presence of both H2O and CO2 in the magma. The core siderite carbonatite is the richest in Fe (48.64-70.85 wt% Fe2O3) and the poorest in Ca (up 0.82 wt% CaO) example of a siderite carbonatite yet recognized The ferrocarbonatite has significant contents of Mn, Ba, Th, Pb and LREE, and a very high Nb (up to 7667 ppm) content due to the presence of Nb-brookite. The substitution 3Ti4+ = Fe2+ + 2Nb5+ recognized in Nb-rich brookite explains enrichment of Nb in the core siderite carbonatite and indicates formation in a reducing environment. The high Nb/Ta ratio (1408-11,459) of the carbonatite is compatible with residual liquids derived by fractional crystallization. The 87Sr/86Sr (0.70411-0.70573) and 144Nd/143Nd (0.512663-0.512715) isotopic data suggest the carbonatite is mantle-derived with essentially no crustal contamination and is younger than the maximum age of 1328 ± 58 Ma (UPb in zircon). We suggest that the Morro dos Seis Lagos carbonatite complex represents the upper-most parts of a differentiated carbonatite magmatic system, and that the siderite carbonatite is related to late-magmatic-to-carbo-hydrothermal processes.
DS202107-1099
2021
Pereira, V.P.Giovannini, A.L., Bastos Neto, A.C., Porto, C.G., Takehara, L., Pereira, V.P., Bidone, M.H.REE mineralization (primary, supergene and sedimentary) associated to the Morro dos Seis Lagos Nb( REE, Ti) deposit (Amazonas, Brazil).Ore Geology Reviews, doi.org/10.1016/ j.oregeorev. 2021.104308 59p. PdfSouth America, BrazilREE

Abstract: In the Morro dos Seis Lagos Nb (Ti, REE) deposit (MSLD), Amazonas state, Brazil, there are four types of REE mineralization: primary, associated to siderite carbonatite; supergene, associated to laterite profile; and sedimentary (detrital and authigenic). The mineralogical and geochemical evolutions of the REE in these domains are integrated into a comprehensible metallogenic model. The main primary ore in the core siderite carbonatite is 52 m thick with 1.47 wt% REE2O3 mainly in monazite-(Ce) and bastnäsite. However, considering the entire section intersected in the core siderite carbonatite, the average grade drops to 0.7 wt% REE2O3 mainly contained in thorbastnasite. In the border siderite carbonatite, the REE mineralization is hydrothermal [rhabdophane-(Ce) and REE-rich gorceixite]. The LREE and phosphates are concentrated at the reworked laterites from where the HREE were leached. With the advance of lateritization, pyrochlore was completely decomposed. The final secondary Ce-pyrochlore was progressively enriched in Ce4+ with loss in REE3+, resulting in the breakdown of the structure and release Ce under strongly oxidizing conditions (high Ce4+/Ce3+) thus forming extremely pure cerianite-(Ce). This mineral occurs intercalated with goethite bands in the lower part of the weathering profile, represented by the brown laterite, and forms intergrowth with hollandite in the manganiferous laterite, formed in a more alkaline environment closer to the water table. The brown laterite has 1.30 wt% REE2O3, the manganese laterite has 1.54 wt% REE2O3, of which 1.42 wt% is Ce2O3. Tectonic and karstic processes over the carbonatite formed several sedimentary basins. In the Esperança Basin, the sedimentary record (233 m thick) shows the whole evolution of the MSLD. The base of the basin (layer 5) is formed by abundant carbonatite fragments, have florencite-(Ce) mineralization with 1.07 wt% REE2O3; layer 4 is formed by carbonatite fragments interbedded with clayey bed; layer 3 is a rhythmite deposited in a lacustrine environment, with clasts of ferruginous materials related to early stages of carbonatite alteration; layer 2 is made up by clays, is rich in organic matter, has authigenic florencite-(Ce), florencite-(La) and base metals. This layer marks the inversion of the relief and the input into the basin of REE leached from the upper laterites, carried by the groundwater flow; layer 1 was formed by the oxidation of the upper part of layer 2. Layers 1 + 2 have 73 m thick and average of 1.72 wt% REE2O3.
DS201503-0133
2015
Pereira Soares, J.E.Araujo e Azevedo, P., Peres Rocha, M., Pereira Soares, J.E., Fuck, R.A.Thin lithosphere beween the Amazonian and Sao Francisco cratons, in central Brazil, revealed by seismic P wave tomography.Geophysical Journal International, Vol. 201, 1, pp. 61-69.South America, BrazilGeophysics - seismic

Abstract: Results of P-wave traveltime seismic tomography in central Brazil unravel the upper-mantle velocity structure and its relationship with the tectonic framework. Data were recorded between 2008 and 2012 at 16 stations distributed over the study area, and were added to the database used by Rocha et al. to improve the resolution of anomalies, and to image the surrounding regions. The main objective was to observe the upper-mantle boundary zone between the Amazonian and São Francisco cratons, represented by mobile belts, inside the Tocantins Province, and to study the lithosphere related to the collision between these two cratons during the Neoproterozoic. A set of low-velocity anomalies was observed crossing the study area in the NE–SW direction, in agreement with the main trend of the Transbrasiliano lineament. The region where the anomalies are located was interpreted as the zone separating the Amazonian and São Franciscan palaeoplates. There is a good correlation between the low-velocity anomalies and the high seismicity of this region, suggesting that it is a region of weakness, probably related to lithospheric thinning. High velocities were observed under the Amazonian and São Francisco cratons. A model is proposed for the lithospheric subsurface in central Brazil, emphasizing the boundary zone between the main palaeoplates in the study area. After merging both databases, the low-velocity anomalies in the central part of the study area suggest tectonic partitioning of the lithosphere. Synthetic tests show that the tomography results are robust.
DS1910-0080
1910
Perels, K.F.L.Perels, K.F.L.Das Bergrechhtsabkommen Vom It. Feb 2 April 1908 und die BerBerlin: E.s. Mittler., 25P.Southwest Africa, NamibiaDiamond, Mining, Law
DS200612-1309
2006
Perelyaev, V.I.Simonov, V.A., Sklyarov, E.V., Kovyazin, S.V., Perelyaev, V.I.Physicochemical parameters of oldest boninite melts.Doklady Earth Sciences, Vol. 408, 4, pp. 667-670.RussiaBoninites
DS201502-0097
2015
Perepechko, Y.Sharapov, V., Sorokin, K., Perepechko, Y.Dynamics of mantle rock metasomatic transformation in permeable lithospheric zones beneath Siberian craton.Economic Geology Research Institute 2015, Vol. 17,, # 2153, 1p. AbstractRussiaGeothermometry
DS201012-0686
2009
Perepechko, Yu.V.Sharapov, V.N.,Chudnenko, K.V., Mazurov, M.P., Perepechko, Yu.V.Metasomatic zoning of subduction lithosphere in Siberia: physiochemical modeling.Russian Geology and Geophysics, Vol. 50, 12, pp. 1107-1118.Russia, SiberiaSubduction
DS201412-0674
2014
Perepechko, Yu.V.Perepechko, Yu.V., Sharapov, V.N.Conditions of appearance of the asthenospheric layer under upper mantle convection.Doklady Earth Sciences, Vol. 457, 1, pp. 901-904.MantleConvection
DS1987-0767
1987
Perepelov, A.B.Volynets, P.N., Anoshin, G.N., Puzankov, Yu.M., Perepelov, A.B.Potassic basaltic rocks of western Kamchatka. Emplacement oflamproiteseries. (Russian)Geol. Geofiz., (Russian), No. 11, pp. 41-50GlobalShonkinite, Absarokite, Lamproite
DS2001-0908
2001
Perepelov, A.B.Perepelov, A.B., Volynets, O.N., Anoshin, Puzankov etcWestern Kamchatka alkali basaltoid volcanism: geological and geochemical review.Alkaline Magmatism -problems mantle source, pp. 52-68.Russia, KamchatkaAlkaline rocks, Geochemistry
DS200512-0843
2003
Perepelov, A.B.Perepelov, A.B., Antipin, V.S., Kablukov, A.V., Filosofova, T.M.Ultrapotassic rhyolites of southern Kamchatka: geochemical and petrological evidence.Plumes and problems of deep sources of alkaline magmatism, pp. 171-183.RussiaAlkalic
DS200512-0844
2001
Perepelov, A.B.Perepelov, A.B., Volynets, O.N., Anoshin, G.N., Puzankov, Yu.M., Antipin, V.S., Kalukov, A.V.Western Kamchatka alkali potassic basaltoid volcanism: geological and geochemical review.Alkaline Magmatism and the problems of mantle sources, pp. 52-68.Russia, KamchatkaAlkalic
DS200612-1074
2006
Perepelov, A.B.Perepelov, A.B., Puzankov, M.Yu., Ivanov, A.V., Filosofova, T.M.Basanites of Mt. Khukhch: first mineralogical geochemical dat a on the Neogene K Al alkaline magmatism in western Kamchatka.Doklady Earth Sciences, Vol. 409, 5, pp. 762-764.RussiaBasanites, Foidites
DS200712-0834
2007
Perepelov, A.B.Perepelov, A.B., Puzankov, M.Yu., Ivanov, Filosfova, Demonetova, Smirnova, Chuvshaova, YasnyginaNeogene basanites in western Kamchatka: mineralogy, geochemistry and geodynamic setting.Petrology, Vol. 15, 5, Sept. pp. 488-508.Russia, KamchatkaBasanites, Foidites
DS201801-0025
2018
Perepelov, A.B.Ivanov, A.V., Demonterova, E.I., Savatenkov, V.M., Perepelov, A.B., Ryabov, V.V., Shevko, A.Y.Late Triassic (Carnian) lamproites from Norilsk, polar Siberia: evidence for melting of the recycled Archean crust and the question of lamproite source for some placer diamond deposits of the Siberian craton.Lithos, Vol. 296-299, pp. 67-78.Russia, Siberialamproites

Abstract: Two typical lamproitic dykes were found in Noril'sk region of the north-western Siberian Craton, which according to mineralogical, geochemical and isotopic criteria belong to anorogenic, non-diamondiferous type of lamproites. According to the geologic relationships, they cut through the Noril'sk-1 intrusion of the Siberian flood basalt province and thus are younger than ~251 Ma. 40Ar/39Ar dating of the two dykes yielded ages of 235.24 ± 0.19 Ma and 233.96 ± 0.19 Ma, showing that they were emplaced in Carnian of the Late Triassic, about 16 Ma after the flood basalt event. There are some indications that there were multiple lamproitic dyke emplacements, including probably emplacement of diamondiferous lamproites, which produced Carnian-age diamond-rich placer deposits in other parts of the Siberian Craton and in adjacent regions. Lead isotope modelling shows that the source of the studied lamproites was formed with participation of recycled crust, which underwent modification of its U/Pb ratio as early as 2.5 Ga. However, the exactmechanismof the recycling cannot be deciphered now. It could be either through delamination of the cratonic crust or subduction of amix of ancient terrigenous sediments into the mantle transition zone.
DS200612-0014
2006
Peres, G.G.Alkmim, F.F., Marshak, S., Pedrosa Soares, A.C., Peres, G.G., Cruz, S.C., Whittington, A.Kinematic evolution of the Aracuai West Congo in Brazil and Africa: nutcracker tectonics during the Neoproterozoic assembly of Gondwana.Precambrian Research, Vol. 149, 1-2, pp. 43-64.South America, BrazilTectonics - collisional, orogen
DS201503-0133
2015
Peres Rocha, M.Araujo e Azevedo, P., Peres Rocha, M., Pereira Soares, J.E., Fuck, R.A.Thin lithosphere beween the Amazonian and Sao Francisco cratons, in central Brazil, revealed by seismic P wave tomography.Geophysical Journal International, Vol. 201, 1, pp. 61-69.South America, BrazilGeophysics - seismic

Abstract: Results of P-wave traveltime seismic tomography in central Brazil unravel the upper-mantle velocity structure and its relationship with the tectonic framework. Data were recorded between 2008 and 2012 at 16 stations distributed over the study area, and were added to the database used by Rocha et al. to improve the resolution of anomalies, and to image the surrounding regions. The main objective was to observe the upper-mantle boundary zone between the Amazonian and São Francisco cratons, represented by mobile belts, inside the Tocantins Province, and to study the lithosphere related to the collision between these two cratons during the Neoproterozoic. A set of low-velocity anomalies was observed crossing the study area in the NE–SW direction, in agreement with the main trend of the Transbrasiliano lineament. The region where the anomalies are located was interpreted as the zone separating the Amazonian and São Franciscan palaeoplates. There is a good correlation between the low-velocity anomalies and the high seismicity of this region, suggesting that it is a region of weakness, probably related to lithospheric thinning. High velocities were observed under the Amazonian and São Francisco cratons. A model is proposed for the lithospheric subsurface in central Brazil, emphasizing the boundary zone between the main palaeoplates in the study area. After merging both databases, the low-velocity anomalies in the central part of the study area suggest tectonic partitioning of the lithosphere. Synthetic tests show that the tomography results are robust.
DS201902-0306
2018
Peres Rocha, M.Peres Rocha, M., Assumpcao, M., Fuck, R., Araujo de Azevedo, P., Penna, Crepaldi Affonso, G.M., Sousa Lima Costa, I., Farrapo Albuquetque, D.Llithosphere expression of the boundary between the Amazonian and extra-Amazonian domains of the South American platform from travel time seismic tomography.Researchgate, AGU 1p. Preprint pdfSouth Americacraton

Abstract: The South American platform is the stable part of the South American plate, unaffected by the orogenesis of the Andes and the Caribbean. Its basement is composed of Archean and Proterozoic cratonic blocks amalgamated by mobile belts, and can be separated in two large domains or continental masses: 1) The Amazonian, Northwest-west portion, including the Amazonian craton, related to the Laurentia supercontinent; and 2) the extra-Amazonian, Central-southeast or Brasiliano domain, related to West Gondwana, formed of several paleocontinental fragments, where the São Francisco and Rio de La Plata cratons and the Paranapanema block are the largest. It has been suggested that these two domains are separated by the Transbrasiliano Lineament to the south and the Araguaia Fold Belt to the north. Teleseismic P waves from 4,989 earthquakes recorded by 339 stations operated mainly in Brazil in the last 25 years have been used for relative-time tomography. The Amazonian domain is predominantly characterized by higher velocities. The SW (extra-Amazonian) domain is characterized by several blocks with high velocities, such as in and around the Sao Francisco Craton, and the Paranapanema block. Results of P-wave travel time tomography allowed to observe a strong low-velocity anomaly near 100-200 km depth following the Araguaia-Paraguay fold belt. This strong low-velocity anomaly could be considered the limit between these two domains, reaching lithospheric depths, and does not necessarily follow the Transbrasiliano lineament, especially in its southern portion.
DS2000-0457
2000
Peres. G.G.Jordt-Evangelista, H., Macambira, M., Peres. G.G., Limalead/lead single zircon dating of Paleoproterozoic calc-alkaline /alkaline magmatism in Sao Francisco...Igc 30th. Brasil, Aug. abstract only 1p.Brazil, Minas GeraisCraton - southeastern border, Geochronology
DS202008-1407
2020
Peresetskaya, E.V.Kargin, A.V., Nosova, A.A., Sazonova, L.V., Peresetskaya, E.V., Golubeva, Yu.Yu., Lebedeva, N.M., Tretyachenko, V.V., Khvostikov, V.A., Burmii, J.P.Ilmenite from the Arkangelsk diamond province, Russia: composition, origin and indicator of diamondiferous kimberlites.Petrology, Vol. 28, 4, pp. 341-369. pdfRussia, Archangelilmenite

Abstract: To provide new insights into the origin and evolution of kimberlitic magmas with different diamond concentrations from the Arkhangelsk diamond province in northwestern Russia, we examined the major-and trace-element compositions of ilmenite from diamondiferous kimberlite of the Grib pipe and diamond barren kimberlites from the Kepino cluster (Stepnaya and TsNIGRI-Arkhangelskaya pipes). Ilmenite from diamond-barren kimberlites shows lower Mg, Ti, Cr, Ni and Cu concentrations with increase in both Fe 3+ and Fe 2+ and Nb, Ta, Zr, Hf, Zn and V concentrations. The main differences between kimberlites with different diamond contents are the Nb and Zr concentrations and their correlation patterns with Mg and Cr concentrations. Ilmenite from the Grib kimberlite has Zr concentrations <110 ppm, whereas ilmenite from the Kepino kimberlites has Zr concentrations >300 ppm. Ilmenite crystallisation within the Grib kimberlite occurred under increasing oxygen fugacity (fO 2), which may reflect assimilation of mantle peridotite by the kimberlitic magmas. Ilmenite from the Kepino kimberlites suggests its crystallisation under constant fO 2 , with the ilmenite composition being controlled by processes of fractional crystallisation of megacrystic minerals. These assumptions were confirmed with assimilation-fractional crystallisation calculations. On the basis of obtained data, we developed a model for the evolution of the kimberlitic magmas for both diamon-diferous and barren kimberlites. The diamond-bearing kimberlitic magmas were generated under intense interaction of kimberlitic magmas with the surrounding lithospheric mantle. It may be that during early modification of the lithospheric mantle by kimberlitic magmas as well as with kimberlitic magmas' local stretching and swift ascent, the capture of the mantle xenoliths was favoured over the crystallisation of phenocrysts. The formation of barren kimberlitic magmas may have occurred when the lithospheric mantle in the vicinity of ascending magmas was already geochemically equilibrated with them. It also is possible that the magma's ascent slowed under conditions of dominantly compressive stresses with crystallisation of olivine and other megacrystic phases.
DS202010-1849
2020
Peresetskaya, E.V.Kargin, A.V., Nosova, A.A., Sazonova, L.V., Peresetskaya, E.V., Golubeva, Yu.Yu., Lebedeva, N.M., Tretyachenko, V.V., Khvostikov, V.A., Burmii, J.P.Ilmenite from the Arkangelsk diamond province, Russia: composition, origin and indicator of diamondiferous kimberlites.Petrology, Vol. 28, 4, pp. 315-337. pdfRussia, Archangeldeposit - Grib, Kepino cluster

Abstract: To provide new insights into the origin and evolution of kimberlitic magmas with different diamond concentrations from the Arkhangelsk diamond province in north-western Russia, we examined the major- and trace-element compositions of ilmenite from diamondiferous kimberlite of the Grib pipe and diamond-barren kimberlites from the Kepino cluster (Stepnaya and TsNIGRI-Arkhangelskaya pipes). Ilmenite from diamond-barren kimberlites shows lower Mg, Ti, Cr, Ni and Cu concentrations with increase in both Fe3+ and Fe2+ and Nb, Ta, Zr, Hf, Zn and V concentrations. The main differences between kimberlites with different diamond contents are the Nb and Zr concentrations and their correlation patterns with Mg and Cr concentrations. Ilmenite from the Grib kimberlite has Zr concentrations <110 ppm, whereas ilmenite from the Kepino kimberlites has Zr concentrations >300 ppm. Ilmenite crystallisation within the Grib kimberlite occurred under increasing oxygen fugacity (fO2), which may reflect assimilation of mantle peridotite by the kimberlitic magmas. Ilmenite from the Kepino kimberlites suggests its crystallisation under constant fO2, with the ilmenite composition being controlled by processes of fractional crystallisation of megacrystic minerals. These assumptions were confirmed with assimilation-fractional crystallisation calculations. On the basis of obtained data, we developed a model for the evolution of the kimberlitic magmas for both diamondiferous and barren kimberlites. The diamond-bearing kimberlitic magmas were generated under intense interaction of kimberlitic magmas with the surrounding lithospheric mantle. It may be that during early modification of the lithospheric mantle by kimberlitic magmas as well as with kimberlitic magmas’ local stretching and swift ascent, the capture of the mantle xenoliths was favoured over the crystallisation of phenocrysts. The formation of barren kimberlitic magmas may have occurred when the lithospheric mantle in the vicinity of ascending magmas was already geochemically equilibrated with them. It also is possible that the magma’s ascent slowed under conditions of dominantly compressive stresses with crystallisation of olivine and other megacrystic phases.
DS202108-1301
2021
Peresetskaya, E.V.Nosova, A.A., Kopylova, M.G., Sazonova, L.V., Vozniak, A.A., Kargin, A.V., Lebedeva, N.M., Volkova, G.D., Peresetskaya, E.V.Petrology of lamprophyre dykes in the Kola alkaline carbonatite province.Lithos, Vol. 398-399. 106277Russia, Kola Peninsulacarbonatite

Abstract: The study reports petrography, bulk major and trace element compositions of lamprophyric Devonian dykes in three areas of the Kola Alkaline Carbonatite Province (N Europe). Dykes in one of these areas, Kandalaksha, are not associated with a massif, while dykes in Kandaguba and Turij Mys occur adjacent (< 5 km) to coeval central multiphase ultramafic alkaline?carbonatitic massifs. Kandalaksha dyke series consists of aillikites - phlogopite carbonatites and monchiquites. Kandaguba dykes range from monchiquites to nephelinites and phonolites; Turij Mys dykes represent alnöites, monchiquites, foidites, turjaites and carbonatites. Some dykes show extreme mineralogical and textural heterogeneity and layering we ascribe to fluid separation and crystal cumulation. Melt evolution of the dykes was modelled with Rhyolite-MELTS and compared with the observed order and products of the crystallization. Our results suggest that the studied rocks were related by fractional crystallization and liquid immiscibility. Primitive melts of aillikites or olivine melanephelinites initially evolved at P = 1.5-0.8 GPa without a SiO2 increase due to abundant clinopyroxene crystallization controlled by the CO2-rich fluid. At 1-1.1 GPa the Turij Mys melts separated immiscible carbonatite melt, which subsequently exsolved late carbonate-rich fluids extremely rich in trace elements. Kandaguba and Turij Mys melts continued to fractionate at lower pressures in the presence of hydrous fluid to the more evolved nephelinite and phonolite melts. The studied dykes highlight the critical role of the parent magma chamber in crystal fractionation and magma diversification. The Kandalaksha dykes may represent a carbonatite - ultramafic lamprophyre association, which fractionated at 45-20 km in narrow dykes on ascent to the surface and could not get more evolved than monchiquite. In contrast, connections of Kandaguba and Turij Mys dykes to their massif magma chambers ensured the sufficient time for fractionation, ascent and a polybaric evolution. This longevity generated more evolved rock types with the higher alkalinity and an immiscible separation of carbonatites.
DS201511-1831
2015
Peretti, A.Deljanin, B., Alessandri, M., Peretti, A., Astrom, M.NDT breaking the 10 carat barrier: world record faceted and gem-quality synthetic diamonds.Contributions to Gemology, Vol. 15, pp. 1-7.TechnologySynthetics

Abstract: The first small manufactured industrial diamonds were produced in 1953 by the Swedish company ASEA but their accomplishment went unannounced. In 1970, General Electric (GE) produced synthetic diamond crystals using the HPHT method with a belt type of press and created a 0.78ct polished RBC colorless diamond. In the 1980’s and 1990’s Russians used their own technology (“BARS” and “TOROID” high pressure apparatus (HPA) with high pressure presses of up to 25 MN load) to grow industrial and crystals up to 2.00ct in polished size, mostly orange to yellow in colour. In the last 15 years, companies including Lucent, Chatham, AOTC, Gemesis (now IIa Technologies) and many other producers in China, Germany, India, Russia, Ukraine, USA and Taiwan have improved the technology yet again and used their expertise to successfully grow diamond crystals that cut to 1.00ct up to 2.00ct in size. This “next generation” of diamonds exhibited high clarities (VS and VVS) and colours (D-H), as well as new blue and pink colours (after irradiation). Other companies (ref. 2-3) including Scio Diamonds, Washington Diamonds, Taidiam, PDC diamonds and Pure Grown Diamonds (selling arm of IIa technologies) are also using a very different technology/process of Chemical Vapour Deposition (CVD) to produce laboratory-grown diamonds up to 3.00 ct in size (table 1).
DS2001-1156
2001
PerezThorkelson, D.J., Mortensen, Davidson, Creaser, PerezEarly Mesoproterozoic intrusive breccias in Yukon: the role of hydrothermal systems in reconstruction of NA.Precambrian Research, Vol. 111, No. 1-4, pp. 31-55.Canada, United States, Australia, YukonTectonics
DS2002-1530
2002
PerezSpencer, R.M., Montenegro, J.L., Gaibor,Perez,MantillaThe Portovelo Zaruma mining camp: southwest Ecuador: porphyry and epithermal environments.Seg Newsletter, No. 49, April, pp. 1,8-14.EcuadorCopper, gold, Deposit - Portovelo Zaruma, R-Nivel, Muluncay
DS200512-0784
2004
Perez, A.M.Niu, F., Perez, A.M.Seismic anistropy in the lower mantle: a comparison of waveform splitting of SKS and SKKS.Geophysical Research Letters, Vol. 31, 24, L24612 DOI 10.1029/2004 GLO21196MantleGeophysics - seismics
DS2002-1305
2002
Perez, D.J.Ramos, V.A., Cristallini, E.O., Perez, D.J.The Pampean flat slab of the central AndesJournal of South American Earth Sciences, Vol.15,1,Apr.pp.59-78.Chile, AndesSubduction, Slab
DS200912-0580
2009
Perez, F.Perez, F., Scanchez, L.E.Assessing the evolution of sustainability reporting in the mining sector. ( figures and information from 2002-2006)Environmental Management, Vol. 43, pp. 949-961.GlobalCorporate sustainability - CSR not specific to diamonds
DS201112-0822
2011
Perez, M.Prejeant, K., Perez, M., White, J.C., Ren, M.Geology of the Elliot County kimberlite, Kentucky.Geological Society of America, Annual Meeting, Minneapolis, Oct. 9-12, abstractUnited States, KentuckyKimberlite petrology
DS201112-0823
2011
Perez, M.Prejeant-Dickerson, K., Perez, M., White, J.C., Lierman, R.T., Ren, M.Mineral geochemistry of the Elliot County kimberlite, Kentucky.Geological Society of America, Annual Meeting, Minneapolis, Oct. 9-12, abstractUnited States, KentuckyKimberlite dikes
DS200712-0115
2006
Perez Estaun, A.Brown, D., Puchkov, V., Alvarez Marron, J., Bea, F., Perez Estaun, A.Tectonic processes in the southern and middle Urals: an overview.Geological Society of London Memoir, No. 32, pp. 407-420.Russia, Europe, UralsTectonics
DS202108-1315
2021
Perez-Diaz, L.Wouters, M.C., Perez-Diaz, L., Tuck-Martin, A., Eagles, G., Adam, J., Grovers, R.Dynamics of the African plate 75Ma: from plate kinematic reconstructions to interplate paleo-stresses,Tectonics, e2020TC006355Africageodynamics

Abstract: Plate reconstruction studies show that the Neotethys Ocean was closing due to the convergence of Africa and Eurasia toward the end of the Cretaceous. The period around 75 Ma reflects the onset of continental collision between the two plates as convergence continued to be taken up mostly by subduction of the Neotethys slab beneath Eurasia. The Owen transform plate boundary in the northeast accommodated the fast northward motion of the Indian plate relative to the African plate. The rest of the plate was surrounded by mid-ocean ridges. Africa was experiencing continent-wide rifting related to northeast-southwest extension. We aim to quantify the forces and paleostresses that may have driven this continental extension. We use the latest plate kinematic reconstructions in a grid search to estimate horizontal gravitational stresses (HGSs), plate boundary forces, and the plate's interaction with the asthenosphere. The contribution of dynamic topography to HGSs is based on recent mantle convection studies. We model intraplate stresses and compare them with the strain observations. The fit to observations favors models where dynamic topography amplitudes are smaller than 300 m. The results also indicate that the net pull transmitted from slab to the surface African plate was low. To put this into context, we notice that available tectonic reconstructions show fragmented subduction zones and various colliding micro-continents along the northern margin of the African plate around this time. We therefore interpret a low net pull as resulting from either a small average slab length or from the micro-continents' resistance to subduction.
DS2001-0135
2001
Perez-EstaunBrown, D., Alvarez-Marron, J., Perez-Estaun, PuchkovStructure and evolution of the Magnitogorsk forearc basin: identifying upper crustal processes during arcTectonics, Vol. 20, No. 3, June pp. 364-75.Russia, UralsTectonics, arc terranes, subduction zone
DS1997-0134
1997
Perez-Estaun, A.Brown, D., Alvarez-Marron, Perez-Estaun, A., GorozhaninaGeometric and kinematic evolution of the foreland thrust and fold belt In the southern UralsTectonics, Vol. 16, No. 3, June, pp. 551-562GlobalTectonics
DS2001-0909
2001
Perez-Gussinye, M.Perez-Gussinye, M., Reston, T.J.Rheological evolution during extension at nonvolcanic rifted margins: onset of serpentinization and develop..Journal of Geophysical Research, Vol. 106, No. 3, Mar. 10, pp. 3961-76.GondwanaTectonics - rifting continental breakup
DS200712-0835
2007
Perez-Gussinye, M.Perez-Gussinye, M., Lowry, A.R., Watts, A.B.Effective elastic thickness of South America and its implications for intracontinental deformation.Geochemistry, Geophysics, Geosystems: G3, Vol. 8, Q05009.South AmericaGeothermometry
DS200912-0581
2009
Perez-Gussinye, M.Perez-Gussinye, M., Metois, M., Fernandez, M., Verges, J., Fullea, J., Lowry, A.R.Effective elastic thickness of Africa and its relationship to other proxies for lithospheric structure and surface tectonics.Earth and Planetary Science Letters, Vol. 287, 1-2, pp. 152-167.AfricaTectonics
DS201112-0481
2011
Perez-Gussinye, M.Jemenez-Munt, I., Fernandez, M., Verges, J., Garcia-Castellanos, D., Fullea, J., Perez-Gussinye, M., Afonso, J.C.Decoupled crust mantle accommodation of Africa-Eurasia convergence in the NW Moroccan margin.Journal of Geophysical Research, Vol. 116, B08403, 12p.Africa, MoroccoGeophysics - density
DS201901-0008
2018
Perezhogin, I.A.Blank, V.D., Churkin, V.D., Kulnitsky, B.A., Perezhogin, I.A., Kirichenko, A.N., Erohin, S.V., Sorokin, P.B., Popov, M.Y.Pressure induced transformation of graphite and diamond to onions.Crystals MDPI, Vol. 8, 2, 8p. Doi.org/10.3390/cryst8020068Russiacarbon nanotubes

Abstract: In this study, we present a number of experiments on the transformation of graphite, diamond, and multiwalled carbon nanotubes under high pressure conditions. The analysis of our results testifies to the instability of diamond in the 55-115 GPa pressure range, at which onion-like structures are formed. The formation of interlayer sp3-bonds in carbon nanostructures with a decrease in their volume has been studied theoretically. It has been found that depending on the structure, the bonds between the layers can be preserved or broken during unloading.
DS1993-0967
1993
Perez-Torrado, F.J.Mangas, J., Perez-Torrado, F.J., Reguilon, R., Martin-Izard, A.Geological characteristics of alkaline rocks and carbonatites of Fuerteventura (Canary Islands, Spain) and their rare earth elements (REE) ore potential.Terra Abstracts, IAGOD International Symposium on mineralization related to mafic, Vol. 5, No. 3, abstract supplement p. 32.GlobalCarbonatite
DS201312-0700
2013
Perez-Valera, F.Perez-Valera, L.A., Rosenbaum, G., Sabchez-Gomez, M., Azor, A., Fernadez-Soler, J.M., Perez-Valera, F., Vasconcelos, P.M.Age distribution of lamproites along the Socovos fault ( southern Spain) and lithospheric scale tearing.Lithos, Vol. 180-181, pp. 252-263.Europe, SpainLamproite
DS201312-0700
2013
Perez-Valera, L.A.Perez-Valera, L.A., Rosenbaum, G., Sabchez-Gomez, M., Azor, A., Fernadez-Soler, J.M., Perez-Valera, F., Vasconcelos, P.M.Age distribution of lamproites along the Socovos fault ( southern Spain) and lithospheric scale tearing.Lithos, Vol. 180-181, pp. 252-263.Europe, SpainLamproite
DS201612-2283
2016
Perez-Valera, L.A.Cambeses, A., Garcia-Casco, A., Scarrow, J.H., Montero, P., Perez-Valera, L.A., Bea, F.Mineralogical evidence for lamproite magma mixing and storage at mantle depths: Socovos fault lamproites, SE Spain.Lithos, Vol. 266-267, pp. 182-201.Europe, SpainLamproite

Abstract: Detailed textural and mineral chemistry characterisation of lamproites from the Socovos fault zone, SE Spain Neogene Volcanic Province (NVP) combining X-ray element maps and LA-ICP-MS spot analyses has provided valuable information about mantle depth ultrapotassic magma mixing processes. Despite having similar whole-rock compositions, rocks emplaced in the Socovos fault are mineralogically varied: including type-A olivine-phlogopite lamproites; and type-B clinopyroxene-phlogopite lamproites. The Ol-lacking type-B predates Ol-bearing type-A by c. 2 million years. We propose that the mineralogical variations, which are representative of lamproites in the NVP as a whole, indicate mantle source heterogeneities. Major and trace element compositions of mineral phases suggest both metasomatised harzburgite and veined pyroxenite sources that were most likely closely spatially related. Thin section scale textural and compositional variations in mineral phases reveal heterogeneous mantle- and primitive magma-derived crystals. The variety of crystals points to interaction and mingling-mixing of ultrapotassic magma batches at mantle depths prior crustal emplacement. The mixing apparently occurred in a mantle melting zone with a channelised flow regime and localised magma chambers-reservoirs. Magma interaction was interrupted when the Socovos and other lithosphere-scale faults tore down to the mantle source region, triggering rapid ascent of the heterogeneous lamproite magma.
DS201611-2146
2016
Perfilev, V.V.Vladykin, N.V., Alymova, N.V., Perfilev, V.V.Geochemical features of rare metal granites of the Zashikhinsky Massif, East Sayan. ( tantalum)Petrology, Vol. 24, 5, pp. 512-525.Russia, IrkutskRare earths

Abstract: The paper presents detailed geochemical data on the rocks of the Zashikhinsky Massif and mineralogical-geochemical characteristics of the ores of the eponymous deposit. The rare-metal granites are divided into three facies varieties on the basis of the degree of differentiation and ore potential: early facies represented by microcline-albite granites with arfvedsonite, middle facies represented by leucocratic albite-microcline granites, and late (most ore-bearing) facies represented by quartz-albite granites grading into albitites. Microprobe data were obtained on major minerals accumulating trace elements in the rocks and ores. All facies of the rare-metal granites, including the rocks of the fluorite-rare-metal vein, define single compositional trends in the plots of paired correlations of rock-forming and trace elements. In addition, they also show similar REE patterns and spidergrams. The latter, however, differ in the depth of anomalies of some elements. Obtained geological, petrographic, and geochemical data suggest a magmatic genesis of the rocks of different composition and their derivation from a single magma during its differentiation. On the basis of all characteristics, the Zashikhinskoe deposit is estimated as one of the largest tantalum rare-metal deposits of alkaline-granite type in Russia.
DS1991-0615
1991
Perfilov, V.N.Grinson, A.S., Grinevitski, G.Z., Volynin, A.F., Perfilov, V.N.Deep tectonic criteria of kimberlite localization in southeastBelomorye.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Voll. 317, No. 5, pp. 1172-1177RussiaTectonics, Kimberlite, genesis
DS1975-0379
1976
Perfilyev, A.S.Peyve, A.V., Perfilyev, A.S., Savelyeva, G.N.Depth Inclusions, Kimberlites and the Problem of Continental Drift.Sovetskaya Geologiya., No. 5, PP. 18-31.RussiaGenesis
DS1992-1443
1992
Perfit, M.Sobolev, A., Casey, J.E., Shimizu, N., Perfit, M.Contamination and mixing of Mid Ocean Ridge Basalt (MORB) primary melts: evidence from melt inclusions in Siqueiros picritesEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p.336GlobalExperimental petrology, Picrites
DS1999-0554
1999
Perfit, M.Perfit, M.Earth's oceanic crustEncyclopedia Geochemistry, Marshall and Fairbridge, pp. 179-82.GlobalOceanic - definition
DS200712-0862
2007
Perfit, M.Putirka, K.D., Perfit, M., Ryerson, F.J., Jackson, M.G.Ambient and excess mantle temperatures, olivine thermometry and active vs. passive upwelling.Chemical Geology, Vol. 241, 3-4, pp. 177-206.MantleGeothermometry
DS201707-1377
2017
Perfit, M.Turner, M., Turner, S., Blatter, D., Maury, R., Perfit, M., Yogodzinski, G.Water contents of clinopyroxenes from sub-arc mantle peridotitesIsland Arc, in press available 2p.Europe, Francemassif

Abstract: One poorly constrained reservoir of the Earth's water budget is that of clinopyroxene in metasomatised, mantle peridotites. This study presents reconnaissance Sensitive High-Resolution, Ion Microprobe–Stable Isotope (SHRIMP–SI) determinations of the H2O contents of (dominantly) clinopyroxenes in rare mantle xenoliths from four different subduction zones, i.e. Mexico, Kamchatka, Philippines, and New Britain (Tabar-Feni island chain) as well as one intra-plate setting (western Victoria). All of the sub-arc xenoliths have been metasomatised and carry strong arc trace element signatures. Average measured H2O contents of the pyroxenes range from 70 ppm to 510?ppm whereas calculated bulk H2O contents range from 88 ppm to 3?737?ppm if the variable presence of amphibole is taken into account. In contrast, the intra-plate, continental mantle xenolith from western Victoria has higher water contents (3?447?ppm) but was metasomatised by alkali and/or carbonatitic melts and does not carry a subduction-related signature. Material similar to the sub-arc peridotites can either be accreted to the base of the lithosphere or potentially be transported by convection deeper into the mantle where it will lose water due to amphibole breakdown.
DS201808-1780
2018
Perfit, M.Putirka, K., Tao, Y., Hari, K.R., Perfit, M., Jackson, M.G., Arevalo, Jr. R.The mantle source of thermal plumes: trace and minor element & major oxides of primitive liquids ( and why olivine compositions don't matter).minoscam.org, doi.org/10.2138/am-2018-6192 59p.Mantleforsterite

Abstract: We estimate the mantle source compositions for mantle plumes, and by implication Earth’s lower mantle, by: (a) measuring trace (e.g, Sc, V, Cu) and minor (e.g., Ca, Mn, Ni) element concentrations of high forsterite olivine grains from several plume localities, (b) estimating the parent liquid compositions from which they crystallized, (c) calculating mantle potential temperatures and degrees of partial melting and (d) estimating trace element compositions of depleted and enriched mantle sources. Our sample set includes two continental flood basalt provinces (Emeishan and Deccan), a flood basalt that erupted in a continental rift setting (Baffin Island), our type example of a thermal mantle plume (Hawaii) and lavas from the Siqueiros Transform at the East Pacific Rise, which represent the mid-ocean ridge system. We also present olivine compositions for the peridotite xenoliths from Kilbourne Hole, New Mexico, USA, which are commonly used as primary and secondary analytical standards. We find that trace elements in lava-hosted olivine grains are too far removed from their mantle source to provided anything but greatly hindered views of such. Olivine compositions reflect not only evolving liquid compositions (including partial melting conditions and later fractionation), but also evolving Ol+liq partition coefficients, which mostly increase with decreasing T during crystallization. Mantle compositions, delimited by maximum forsterite contents and estimates of parental magmas (and experimentally determined partition coefficients) indicate that our selected plumes reflect some combination of (1) a depleted mantle source that is quite similar to that obtained by other methods, and (2) a variably enriched plume source that is more enriched than current estimates of pyrolite. The enriched plume mantle sources can be explained remarkably well as a mixture of subducted mid-ocean ridge basalt (MORB; Gale et al. 2013) and depleted MORB mantle (DM; Salters and Stracke 2004), with MORB:DM ratios of 1:5 to 1:4. These ratios are most sensitive to estimates of melt fraction where plume parental magmas are last equilibrated with their mantle source, but are nonetheless consistent across a wide range of chemically very different elements, and estimates of MORB and DM obtained by very different means. Baffin Island is of particular interest. Like prior studies, we verify a high mantle potential temperature (Tp) of 1630oC (compared to Tp = 1320-1420oC for MORB from Cottrell and Kelley 2011 for Ol of Fo89.3-91.4). The Baffin source is also within error the same as DM with respect to trace elements, although still isotopically distinct; Baffin appears to be sourced in something that is akin to DM that lies at the base of the mantle, where plumes acquire their excess heat. Thus while part of our analysis supports the concept of a "slab graveyard" at the bottom of the lower mantle (e.g., Wyession 1996), that cemetery is by no means ubiquitous at the CMB: subducted slabs are either unevenly interred, or efficiently excavated by later upwellings.
DS1989-0523
1989
Perfit, M.R.Goldman, D.S., Perfit, M.R., Ridley, W.I.Petrology and geochemistry of the Thirtynine mile volcanic field, Colorado: an intracontinental shoshonitic suiteNew Mexico Bureau of Mines Bulletin., Continental Magmatism Abstract Volume, Held, Bulletin. No. 131, p. 111. AbstractColoradoShoshonite
DS1993-0897
1993
Perfit, M.R.Lebron, M.C., Perfit, M.R.Stratigraphic and petrochemical dat a support subduction polarity reversalof the Cretaceous Caribbean Island ArcJournal of Geology, Vol. 101, No. 3, May pp. 389-396CaribbeanTectonic models, Calc-alkaline series
DS201912-2824
2019
Perfit, M.R.Shimizu, K., Saal, A.E., Hauri, E.H., Perfit, M.R., Hekinian, R.Evaluating the roles of melt rock interaction and partial degassing on the CO2/Ba ratios of MORB: implications of the CO2 budget in the Earth's depleted upper mantle.Geocimica et Cosmochimica Acta , Vol. 260, pp. 29-48.Mantlemelting

Abstract: Carbon content in the Earth's depleted upper mantle has been estimated in previous studies using CO2/Ba ratios of CO2 undersaturated depleted mid-ocean ridge basalt (D-MORB) glasses and melt inclusions. However, CO2/Ba ratios in CO2 undersaturated MORB may not necessarily record those of the mantle source, as they may be affected by (1) assimilation of Ba-rich plagioclase-bearing rocks in the oceanic crust and (2) CO2 degassing through partial degassing and mixing. In this study, we evaluate these effects on the CO2/Ba ratios as well as other volatile to refractory trace element ratios (H2O/Ce, F/Nd, Cl/K, and S/Dy) in D-MORBs using the compositions of olivine-hosted melt inclusions and glasses from the Siqueiros and Garrett transform faults. The Siqueiros and Garrett melt inclusions are CO2 undersaturated and highly depleted in incompatible trace elements, and their average CO2/Ba ratios show relatively large ranges of 90?±?34 and 144?±?53 respectively. A subset of melt inclusions in lavas from both transform faults show potential signatures of contamination by plagioclase-rich rocks, such as correlations between major elements contents (e.g., FeO, Al2O3, and MgO), and trace element ratios (e.g., Sr/Nd). We find that (1) assimilation fractional crystallization (AFC) of gabbro into D-MORB and (2) mixing between partial melts of gabbro and D-MORB can reproduce the observed range in Sr/Nd ratios as well as the general trends between major elements. However, we find that these processes had limited effects on the CO2/Ba ratio of the melt inclusions and it is unlikely that they can account for the observed range in the CO2/Ba ratio. On the other hand, while a partial degassing and mixing model can generate melts with large range of CO2/Ba ratios (as proposed by Matthews et al. (2017)), it cannot reproduce the Pearson correlation coefficients between CO2/trace element and 1/trace element ratios observed in the Siqueiros and Garrett melt inclusions. Instead, when analytical uncertainties on the elemental concentrations are considered, a model without partial degassing can adequately reproduce the majority of the observed range in CO2/Ba ratio and Pearson correlation coefficients. Hence, we postulate that the Siqueiros and Garrett melt inclusions are undegassed and use their average CO2/Ba ratios to estimate the Siqueiros and Garrett mantle source CO2 contents (21?±?2?ppm and 33?±?6?ppm respectively). We also evaluate the effects of shallow level crustal processes on H2O/Ce, F/Nd, Cl/K, and S/Dy ratios, and after which we filter those effects, we estimate the H2O, F, Cl and S contents in the mantle sources of the Siqueiros (40?±?8?ppm, 8?±?1?ppm, 0.22?±?0.04?ppm, and 113?±?3?ppm) and Garrett (51?±?9?ppm, 6?±?1?ppm, 0.27?±?0.07?ppm, and 128?±?7?ppm) melt inclusions.
DS1995-1484
1995
Periera, E.Periera, E.Photoconductivity of natural diamondsDiamond Relations, Vol. 4, No. 5-6, May 1, pp. 688-691. # QV435GlobalDiamond- natural, Photoconductivity
DS200712-0955
2007
Perilli, S.Schneider, D.A., Heizler, M.T., Bickford, M.E., Wortman, G.L., Condie, K.C., Perilli, S.Timing constraints of orogeny to cratonization: thermochronology of the Paleoproterozoic Trans-Hudson orogen, Manitoba and Saskatchewan, Canada.Precambrian Research, Vol. 153, 1-2, pp. 65-95.Canada, Manitoba, SaskatchewanGeothermometry
DS202106-0956
2021
Pering, T.D.Mason, E, Wieser, P.E., Liu, E.J., Edmonds, M., Ilyinskaya, E., Whitty, R.C., Mather, T.A., Elias, T., Nadeau, P.A., Wilkes, T.C., McGonigle, A.J.S., Pering, T.D., Mims, F.M., Kern, C., Schneider, D.J., Oppenheimer, C.Volatile metal emissions from volcanic gassing and lava-seawater interactions at Kilauea volcano, Hawaii.Earth & Environment Communications, 10.1038/s43247-021-00145-3 16p. PdfUnited States, Hawaiimagmatism

Abstract: Volcanoes represent one of the largest natural sources of metals to the Earth’s surface. Emissions of these metals can have important impacts on the biosphere as pollutants or nutrients. Here we use ground- and drone-based direct measurements to compare the gas and particulate chemistry of the magmatic and lava-seawater interaction (laze) plumes from the 2018 eruption of K?lauea, Hawai’i. We find that the magmatic plume contains abundant volatile metals and metalloids whereas the laze plume is further enriched in copper and seawater components, like chlorine, with volatile metals also elevated above seawater concentrations. Speciation modelling of magmatic gas mixtures highlights the importance of the S2? ligand in highly volatile metal/metalloid degassing at the magmatic vent. In contrast, volatile metal enrichments in the laze plume can be explained by affinity for chloride complexation during late-stage degassing of distal lavas, which is potentially facilitated by the HCl gas formed as seawater boils.
DS200412-1294
2004
Perini, G.Melluso, L., Censi, P., Perini, G., et al.Chemical and isotopic ( C, O, Sr, Nd) characteristics of the Xiluvo carbonatite ( central western Mozambique).Mineralogy and Petrology, Vol. 80, 3-4, March pp. 201-213.Africa, MozambiqueCarbonatite
DS201910-2288
2019
Periotto, B.Nestola, F., Zaffiro, G., Mazzucchelli, M.L., Nimis, P., Andreozzi, G.B., Periotto, B., Princivalle, F., Lenaz, D., Secco, L., Pasqualetto, L., Logvinova, A.M., Sobolev, N.V., Lorenzetti, A., Harris, J.W.Diamond inclusion system recording old deep lithosphere conditions at Udachnaya ( Siberia).Nature Research, Vol. 9, 12586 8p. PdfRussia, Siberiadeposit - Udachnaya

Abstract: Diamonds and their inclusions are unique fragments of deep Earth, which provide rare samples from inaccessible portions of our planet. Inclusion-free diamonds cannot provide information on depth of formation, which could be crucial to understand how the carbon cycle operated in the past. Inclusions in diamonds, which remain uncorrupted over geological times, may instead provide direct records of deep Earth’s evolution. Here, we applied elastic geothermobarometry to a diamond-magnesiochromite (mchr) host-inclusion pair from the Udachnaya kimberlite (Siberia, Russia), one of the most important sources of natural diamonds. By combining X-ray diffraction and Fourier-transform infrared spectroscopy data with a new elastic model, we obtained entrapment conditions, Ptrap?=?6.5(2) GPa and Ttrap?=?1125(32)-1140(33) °C, for the mchr inclusion. These conditions fall on a ca. 35?mW/m2 geotherm and are colder than the great majority of mantle xenoliths from similar depth in the same kimberlite. Our results indicate that cold cratonic conditions persisted for billions of years to at least 200?km in the local lithosphere. The composition of the mchr also indicates that at this depth the lithosphere was, at least locally, ultra-depleted at the time of diamond formation, as opposed to the melt-metasomatized, enriched composition of most xenoliths.
DS1984-0381
1984
Perkin, D.J.Jaques, A.L., Perkin, D.J.A Mica, Pyroxene, Ilmenite Megacryst Bearing Lamprophyre From Mt. Woolooma, Northeastern New South Wales.B.m.r. Journal of Aust., Vol. 9, No. 1, MARCH PP. 33-40.Australia, New South WalesBlank
DS2001-0096
2001
PerkinsBeccaluva, L., Bianchini, G., Coltorti, Perkins, SienaMultistage evolution of the European lithospheric mantle: new evidence Sardinian peridotite xenolithsContributions to Mineralogy and Petrology, Vol. 142, No. 3, Dec. pp. 284-97.SardiniaXenoliths - petrology
DS2001-0097
2001
PerkinsBeccaluva, L., Blanchini, Coltori, Perkins, Siena, et al.Multistage evolution of the European lithospheric mantle: new evidence from Sardinian peridotite xenolithContribution Mineralogy Petrology, Vol. 142, No. 3, pp. 284-97.Sardinia, EuropePeridotite xenoliths
DS1975-0159
1975
Perkins, C.M.Perkins, C.M.A Bibliography of Kimberlites and Related Rocks of Central And Northeast United States with Some Reference on Possible Related Structures: 1785-1974.Msc. Thesis, University Toledo, Toledo Ohio, 146P.Appalachia, Kentucky, Central StatesTectonics, Geology
DS1981-0334
1981
Perkins, D.Perkins, D., Holland, T.J.B., Newton, R.C.The Al2o3 Contents of Enstatite in Equilibrium with Garnet In the System Mgo Al2os Sio2 at 15-40kbar and 900-1, 600c.Contributions to Mineralogy and Petrology, Vol. 78, PP. 99-109.GlobalMineral Chemistry
DS1991-1334
1991
Perkins, D.Perkins, D.Metamorphism of the Kissey new gneisses and related rocks of the ReindeerZone, Trans-Hudson Orogen, northern SaskatchewanCanadian Journal of Earth Sciences, Vol. 28, No. 10, October pp. 1664-1676Saskatchewanmetamorphism, Kisseynew
DS1992-1184
1992
Perkins, D.Perkins, D., Vielzeuf, D.Experimental investigation of iron-magnesium distribution between olivine andclinopyroxene:mixing properties of iron-magnesium in clinopyroxene, garnet-clinopyroxenetherM.American Mineralogist, Vol. 77, No. 7, 8 July-August pp. 774-783GlobalClinopyroxene, Experimental petrology -garnet
DS1992-1185
1992
Perkins, D.Perkins, D., Vielzeuf, D.Experimental investigation of iron, magnesium distribution between olivine and clinopyroxene: implications for mixing properties of iron and magnesium...American Mineralogist, Vol. 77, pp. 774-83.MantleThermometry - garnet clinopyroxene
DS201112-0780
2011
Perkins, D.Perkins, D., Anthony, E.Y.The evolution of spinel lherzolite xenoliths and the nature of the mantle at Kilbourne Hole, New Mexico.Contributions to Mineralogy and Petrology, Vol. 162, 6,pp.1139-1157.United States, New Mexico, Colorado PlateauXenoliths
DS1982-0596
1982
Perkins, D.M.Thenhaus, P.C., Algermissen, S.T., Perkins, D.M.A New Seismic Source Zone Map for the Conterminous United States.Geological Society of America (GSA), Vol. 14, No. 7, P. 630, (abstract.).GlobalMid-continent, Geophysics
DS1989-0180
1989
Perkins, E.H.Bronw, T.H., Berman, R.G., Perkins, E.H.PTA-SYSTEM:a Geo-calc software package for the calculation and display of activity temperature pressure phase diagramsAmerican Mineralogist, Vol. 74, No. 3-4, March-April pp. 485-487GlobalComputer, Program -PTA -system
DS200612-1075
2006
Perkins, G.B.Perkins, G.B., Sharp, Z.D., Selverstone, J.Oxygen isotope evidence for subduction and rift related mantle metasomatism beneath the Colorado Plateau, Rio Grande Rift transition.Contributions to Mineralogy and Petrology, Vol. 151, 6, pp. 633-650.United States, Colorado PlateauGeochronology
DS201112-1071
2011
Perkins, H.C.Vallance, S., Perkins, H.C., Dixon, J.E.What is social sustainability? A clarification of concepts.Geoforum, Vol. 42, 3, June pp. 342-348.TechnologyCSR Classification - overview of concept
DS1970-0619
1973
Perkins, P.Anderson, O.L., Perkins, P.A Plate Tectonics Model Involving Nonlaminar Asthenospheric flow to Account for Irregular Patterns of Magmatism in the Southwestern United States.International Kimberlite Conference FIRST, EXTENDED ABSTRACT VOLUME., PP. 7-10.Colorado PlateauKimberlite, Rocky Mountains
DS1975-0007
1975
Perkins, P.Anderson, O.L., Perkins, P.A Plate Tectonics Model Involving Non-laminar Asthenospheric Flow to Account for Irregular Patterns of Magmatism in The southwestern United States.Physics and Chemistry of the Earth, Vol. 9, PP. 113-122.United States, Colorado Plateau, Rocky MountainsKimberlite Genesis
DS2003-1064
2003
Perkins, R.Perkins, R.Environmental leapfrogging in developing countries: a critical assessment andNatural Resources Forum, Vol. 27, 3, pp. 177-188.AfricaEnvironment
DS200412-1526
2003
Perkins, R.Perkins, R.Environmental leapfrogging in developing countries: a critical assessment and reconstruction.Natural Resources Forum, Vol. 27, 3, pp. 177-188.AfricaEnvironment
DS201909-2048
2019
Perkins, R.Hughes, E.B., Perkins, R.Madagascar saphhires: low-temperature heat treatment experiments.Gems & Gemology, Vol. 55, 7, pp. 184-197..Africa, Madagascarsapphire

Abstract: Madagascar has become one of the world’s top sources of fine blue sapphire in recent times. In addition to beautiful untreated material, increasing numbers of treated stones have appeared in the market. Some have been heated to relatively low temperatures, below 1350°C, to lighten their color. To help separate unheated and heated Madagascar sapphire, the authors performed experiments to document the changes they undergo with low-temperature heat treatment in air, which is an oxidizing atmosphere.
DS2003-1065
2003
Perkins, S.Perkins, S.Seismic waves resolve continental debateScience News, Vol. 163, No. 18, May 13, p. 285.MantleGeophysics - seismics
DS2003-1066
2003
Perkins, S.Perkins, S.Going down? Probe could ride to Earth's core in a mass of molten ironScience News, Vol. 163, No. 20, May 17, p. 307.MantleTechnology
DS200412-1527
2003
Perkins, S.Perkins, S.Seismic waves resolve continental debate.Science News, Vol. 163, No. 18, May 13, p. 285.MantleGeophysics - seismics
DS200412-1528
2003
Perkins, S.Perkins, S.Going down? Probe could ride to Earth's core in a mass of molten iron.Science News, Vol. 163, No. 20, May 17, p. 307.MantleTechnology
DS200812-0883
2008
Perkins, S.Perkins, S.Fingerprinting diamonds via phosphorescence.Science News, Vol. 173, 2, Jan. 12., p. 19. (1p.)TechnologyDiamond - fingerprints
DS201804-0728
2018
Perkins, S.Perkins, S.Pockets of water may lie deep below Earth's surface.sciencemag.org, 10.1126/science.aat5630Mantlegeophysics

Abstract: Small pockets of water exist deep beneath Earth’s surface, according to an analysis of diamonds belched from hundreds of kilometers within our planet. The work, which also identifies a weird form of crystallized water known as ice VII, suggests that material may circulate more freely at some depths within Earth than previously thought. Geophysical models of that flow, which ultimately influences the frequency of earthquakes driven by the scraping of tectonic plates at Earth’s surface, may need to be substantially tweaked, scientists say. Such models also help scientists estimate the long-term rates of heat flow through Earth’s surface and into space.
DS2002-0928
2002
Perkins, W.W.Le Roux, P.J., Le Roex, A.P., Schilling, J.G., Shimizu, N., Perkins, W.W., PearceMantle heterogeneity beneath the southern Mid-Atlantic Ridge: trace element evidenceEarth and Planetary Science Letters, Vol. 203, 1, pp. 479-98.MantleGeochemistry
DS201412-0675
2014
Perlinelli, C.Perlinelli, C., Bosi, F., Andreozzi, G.B., Conte, A.M., Armienti, P.Geothermometric study of Cr-spinels of peridotite mantle xenoliths from northern Victoria Land ( Antarctica).American Mineralogist, Vol. 99, pp. 839-846.AntarcticaSpinel
DS201312-0701
2013
Perlingeiro, G.Perlingeiro, G., Vasconcelos, P.M., Knesel, K.M., Thiede, D.S., Cordani, U.G.40 Ar/39/Ar geochronology of the Fernando de Noronha Archipelago and implications for the origin of alkaline volcanism in the NE Brazil.Journal of Volcanology and Geothermal Research, Vol. 249, pp. 140-154.South America, BrazilAlkalic
DS200512-0213
2005
Perlroth, R.Davidson, J., Chalier, B., Hora, J.M., Perlroth, R.Mineral isochrons and isotopic fingerprinting: pit falls and promises.Geology, Vol. 33, 1, Jan. pp. 29-32.Geochronology, igneous rocks
DS1984-0588
1984
Perminov, A.V.Pliusnin, G.S., Vorobiev, E.I., Perminov, A.V.Isotopic Composition (delta 0 18 and Delta C 13) of Murunskii Alkaline Carbonatites.Doklady Academy of Sciences AKAD. NAUK SSSR., Vol. 275, No. 4, PP. 999-1002.RussiaIsotope, Related Rocks
DS1984-0589
1984
Perminov, A.V.Plyusnin, G.S., Vorobyev, YE. I., Perminov, A.V.Isotopic composition ( Delta 18 O 13C) of carbonatites in the Murunalkalic rock blockDoklady Academy of Science USSR, Earth Science Section, Vol. 275, Mar-Apr. pp. 156-160RussiaIsotope Geochemistry, Carbonatite
DS201312-0401
2014
Pernet-Fisher, J.F.Howarth, G.H., Barry, P.H., Pernet-Fisher, J.F., Baziotis, I.P., Pokhilenko, N.P., Pokhilenko, L.N., Bodnar, R.J., Taylor, L.A.Superplume metasomatism: evidence from Siberian mantle xenoliths.Lithos, Vol. 184-187, pp. 209-224.Russia, SiberiaMetasomatism
DS201412-0373
2014
Pernet-Fisher, J.F.Howarth, G.H., Barry, P.H., Pernet-Fisher, J.F., Baziotis, I.P., Pokhilenko, N.P., Poikhilenko, L.N., Bodnar, R.L., Taylor, L.A., Agashev, A.M.Superplume metasomatism: evidence from Siberian mantle xenoliths.Lithos, Vol. 184-187, pp. 209-224.RussiaMetasomatism
DS201412-0374
2014
Pernet-Fisher, J.F.Howarth, G.H., Sobolev, N.V., Pernet-Fisher, J.F., Barry, P.H., Penumado, D., Puplampu, S., Ketcham, R.A., Maisano, J.A., Taylor, D., Taylor, L.A.The secondary origin of diamonds: multi-modal radiation tomography of Diamondiferous mantle eclogites.International Geology Review, Vol. 56, 9, pp. 1172-1180.Russia, Siberia3D
DS201412-0676
2014
Pernet-Fisher, J.F.Pernet-Fisher, J.F., Howarth, G.H., Liu, Y., Barry, P.H., Carmody, L., Valley, J.W., Bodnar, R.J., Spetsius, Z.V., Taylor, L.A.Komsomolskaya Diamondiferous eclogites: evidence for oceanic crustal protoliths.Contributions to Mineralogy and Petrology, Vol. 167, pp. 1-17.Russia, SiberiaDeposit - Komsomolskaya
DS201504-0183
2015
Pernet-Fisher, J.F.Barry, P.H., Hilton, D.R., Day, J.M.D., Pernet-Fisher, J.F., Howarth, G.H., Magna, T., Agashev, A.M., Pokhilenko, N.P., Opkhilenko, L.N., Taylor, L.A.Helium isotope evidence for modification of the cratonic lithosphere during the Permo-Triassic Siberian flood basalt event.Lithos, Vol. 216-217, pp. 73-80.Russia, SiberiaDeposit - Udachnaya, Obnazhennaya

Abstract: Major flood basalt emplacement events can dramatically alter the composition of the sub-continental lithospheric mantle (SCLM). The Siberian craton experienced one of the largest flood basalt events preserved in the geologic record — eruption of the Permo-Triassic Siberian flood basalts (SFB) at ~250 Myr in response to upwelling of a deep-rooted mantle plume beneath the Siberian SCLM. Here, we present helium isotope (3 He/ 4 He) and concentra-tion data for petrologically-distinct suites of peridotitic xenoliths recovered from two temporally-separated kim-berlites: the 360 Ma Udachnaya and 160 Ma Obnazhennaya pipes, which erupted through the Siberian SCLM and bracket the eruption of the SFB. Measured 3 He/ 4 He ratios span a range from 0.1 to 9.8 R A (where R A = air 3 He/ 4 He) and fall into two distinct groups: 1) predominantly radiogenic pre-plume Udachnaya samples (mean clinopyroxene 3 He/ 4 He = 0.41 ± 0.30 R A (1?); n = 7 excluding 1 outlier), and 2) 'mantle-like' post plume Obnazhennaya samples (mean clinopyroxene 3 He/ 4 He = 4.20 ± 0.90 R A (1?); n = 5 excluding 1 outlier). Olivine separates from both kimberlite pipes tend to have higher 3 He/ 4 He than clinopyroxenes (or garnet). Helium con-tents in Udachnaya samples ([He] = 0.13–1.35 ?cm 3 STP/g; n = 6) overlap with those of Obnazhennaya ([He] = 0.05–1.58 ?cm 3 STP/g; n = 10), but extend to significantly higher values in some instances ([He] = 49– 349 ?cm 3 STP/g; n = 4). Uranium and thorium contents are also reported for the crushed material from which He was extracted in order to evaluate the potential for He migration from the mineral matrix to fluid inclusions. The wide range in He content, together with consistently radiogenic He-isotope values in Udachnaya peridotites suggests that crustal-derived fluids have incongruently metasomatized segments of the Siberian SCLM, whereas high 3 He/ 4 He values in Obnazhennaya peridotites show that this section of the SCLM has been overprinted by Permo-Triassic (plume-derived) basaltic fluids. Indeed, the stark contrast between pre-and post-plume 3 He/ 4 He ra-tios in peridotite xenoliths highlights the potentially powerful utility of He-isotopes for differentiating between various types of metasomatism (i.e., crustal versus basaltic fluids).
DS201504-0202
2015
Pernet-Fisher, J.F.Howarth, G.H., Sobolev, N.V., Pernet-Fisher, J.F., Ketcham, R.A., Maisano, J.A., Pokhilenko, L.N., Taylor, D.3-D X-ray tomography of Diamondiferous mantle eclogite xenoliths, Siberia: a review.Journal of Asian Earth Sciences, Vol. 101, 1, pp. 39-67.RussiaDeposit - Udachnaya
DS201909-2074
2019
Pernet-Fisher, J.F.Pernet-Fisher, J.F., Barry, P.H., Day, J.M.D., Pearson, D.G., Woodland, S., Agashev, A.M., Pokhilenko, L.N., Pokhilenko, N.P.Heterogeneous kimberlite metasomatism revealed from a combined He-Os isotope study of Siberian megacrustalline dunite xenoliths.Geochimica et Cosmochimica Acta, in press available 45p. PdfRussia, Siberiadeposit - Udachnaya East
DS201912-2811
2018
Peron, S.Peron, S., Moreira, M.Onset of volatile recycling into the mantle determined by xenon anomalies.Geochemical Perspectives Letters, Vol. 9, pp. 21-25.Mantleconvection

Abstract: Noble gases serve as unique tracers of the origin and evolution of Earth’s volatile reservoirs owing to their inert nature and contribution from extinct and extant radioactivities. However, noble gases are low in abundance relative to many other elements, particularly in the Earth’s mantle. Additionally, mantle-derived samples show large post-eruptive atmospheric contamination, rendering the determination of the primary mantle composition challenging. The sources of mantle krypton and xenon remain debated due to their partially resolvable excess, if any, relative to the atmosphere. Atmospheric noble gases also appear to be recycled into the mantle via subduction, progressively overprinting the initial mantle signature. Here we develop a new protocol to accumulate non-contaminated mantle-derived xenon, in particular the low abundant 124-126-128Xe. The results show the highest excesses in 124-126-128Xe ever measured in the mantle relative to the atmosphere and point toward a chondritic origin for mantle xenon. The fissiogenic isotopes 131-132-134-136Xe allow the onset of efficient xenon recycling in the mantle to be constrained at around 3 Gyr ago, implying that volatile recycling before 3 Ga would have been negligible.
DS200712-0138
2007
Perona, P.Camporeale, C., Perona, P., Porporato, A., Ridolfi, L.Hierarchy of models for meandering rivers and related morphodynamic processes.Reviews of Geophysics, Vol. 45, 1, RG1001TechnologyGeomorphology
DS1997-0903
1997
Perov, V.A.Perov, V.A., Kononova, V.A., et al.Potassic magmatism of the Aldan shield: an indicator of the multistage evolution of lithospheric mantle.Petrology, Vol. 5, No. 5, Sept-Oct. pp. 415-430.Russia, SiberiaMagmatism, Mantle
DS200512-0845
2005
Perov, V.A.Perov, V.A., Bogomolov, E.S., Larchenko, V.A., Levskii, L.K., Minchenko, G.V., Sablukov, S.M., SZergeev, S.A., Stepanov, V.P.Rb Sr age of kimberlites of the Pionerskaya pipe, Arkangelsk Diamondiferous province.Doklady Earth Sciences, Vol. 400, 1, pp. 67-71.Russia, Kola Peninsula, ArchangelGeochronology -
DS200812-1305
2008
Perova, E.N.Zaitsev, A.N., Keller, J., Spratt, J., Perova, E.N., Kearlsey, A.Nyereite pissonite calcite shortite relationships in altered natrocarbonatites, Oldoinyo Lengai, Tanzania.Canadian Mineralogist, Vol. 46, 4, August pp.Africa, TanzaniaCarbonatite
DS201112-0781
2011
Perova, E.N.Perova, E.N., Zaitsev, A.N.Thermodynamic analysis of the stability of secondary minerals in altered carbonatites from Oldoinyo Lengai, northern Tanzania.Peralk-Carb 2011, workshop held Tubingen Germany June 16-18, PosterAfrica, TanzaniaCarbonatite
DS201112-0782
2011
Perova, E.N.Perova, E.N., Zaitsev, A.N.Thermodynamic analysis of the stability of secondary minerals in altered carbonatites from Oldoinyo Lengai, northern Tanzania.Peralk-Carb 2011... workshop June 16-18, Tubingen, Germany, Abstract p.109-110.Africa, TanzaniaOldoinyo Lengai
DS201112-0783
2011
Perova, E.N.Perova, E.N., Zaitsev, A.N.Thermodynamic analysis of the stability of secondary minerals in altered carbonatites from Oldoinyo Lengai, northern Tanzania.Peralk-Carb 2011... workshop June 16-18, Tubingen, Germany, Abstract p.109-110.Africa, TanzaniaOldoinyo Lengai
DS1960-0385
1963
Perovskiy, S.Perovskiy, S.Geography of Diamond Formation EpochsLeningrad: Pravda., RussiaKimberlite, Kimberley
DS201904-0723
2017
Perozzi, L.Cate, A., Perozzi, L., Gloaguen, E., Blouin, M.Machine learning as a tool for geologists. Not specific to diamondsThe leading Edge, https://dx.doi.org/10.1190/tle36030064.1Globaldata sets

Abstract: Machine learning is becoming an appealing tool in various fields of earth sciences, especially in resources estimation. Six machine learning algorithms have been used to predict the presence of gold mineralization in drill core from geophysical logs acquired at the Lalor deposit, Manitoba, Canada. Results show that the integration of a set of rock physical properties — measured at closely spaced intervals along the drill core — with ensemble machine learning algorithms allows the detection of gold-bearing intervals with an adequate rate of success. Since the resulting prediction is continuous along the drill core, the use of this type of tool in the future will help geologists in selecting sound intervals for assay sampling and in modeling more continuous ore bodies during the entire life of a mine.
DS200612-1076
2006
Perraki, M.Perraki, M., Proyer, A., Mposkos, E., Kaindl, R., Hoinkes, G.Raman micro spectroscopy on diamond, graphite and other carbon polymorphs from the ultrahigh pressure metamorphic Kimi Complex of the Rhodope metamorphic province.Earth and Planetary Science Letters, Vol. 241, 3-4, pp. 672-685.Europe, GreeceUHP
DS200912-0582
2009
Perraki, M.Perraki, M., Korsakov, A.V., Smith, D.C., Mposkos, E.Raman spectroscopic and microscopic criteria for the distinction of microdiamonds in ultrahigh-pressure metamorphic rocks from diamonds in sample preparation materials.American Mineralogist, Vol. 94, pp. 546-556.Russia, Kazakhstan, Europe, Germany, GreeceUHP
DS201012-0406
2010
Perraki, M.Korsakov, A.V., Perraki, M., Zedgenizov, D.A., Bindi, L.Diamond graphite relationships in ultrahigh pressure metamorphic rocks from the Kochetav Massif, northern Kazakhstan.Journal of Petrology, Vol. 51, 3, pp. 763-783.RussiaUHP
DS201412-0677
2014
Perraki, M.Perraki, M., Faryad, S.W.First finding of microdiamond, coesite and other UHP phases in felsic granulites in the Moldanubian Zone: implications for deep subduction and a revised geodynamic model for Variscan Orogeny in the Bohemian Massif.Lithos, Vol. 202-203, pp. 157-166.EuropeCoesite, UHP
DS202006-0928
2020
Perraki, M.Korsakov, A.V., Kohn, M.J., Perraki, M.Applications of raman spectroscopy in metamorphic petrology and tectonics. ( mentions diamond)Elements, Vol. 16, pp. 105-110.Mantlespectroscopy, geothermalbarometry

Abstract: Raman spectroscopy is widely applied in metamorphic petrology and offers many opportunities for geological and tectonic research. Minimal sample preparation preserves sample integrity and microtextural information, while use with confocal microscopes allows spatial resolution down to the micrometer level. Raman spectroscopy clearly distinguishes mineral polymorphs, providing crucial constraints on metamorphic conditions, particularly ultrahigh-pressure conditions. Raman spectroscopy can also be used to monitor the structure of carbonaceous material in metamorphic rocks. Changes in structure are temperature-sensitive, so Raman spectroscopy of carbonaceous material is widely used for thermometry. Raman spectroscopy can also detect and quantify strain in micro-inclusions, offering new barometers that can be applied to understand metamorphic and tectonic processes without any assumptions about chemical equilibrium.
DS1995-0595
1995
Perreault, S.Gaudreau, D., Perreault, S.District miniere de Cote Nord Nouveau Quebec. #2Quebec Department of Mines, DV 95-01, pp. 141-65.Quebec, Ungava, LabradorGeology
DS1998-1539
1998
Perreault, S.Verpaelst, P., Perreault, S., Brisebois, D., BoudriasGeologie de la region de la riviere Koroc, Grand NordQuebec Department of Mines, DV 98-05, p. 35.QuebecGeology
DS2000-0683
2000
Perreault, S.Moorhead, J., Perreault, S., Berclaz, Sharma, BeaumierKimberlites and diamonds in northern QuebecQuebec Department of Mines, Pro 99-09, 11p.Quebec, Ungava, LabradorExploration
DS200412-0810
2004
Perreault, S.Heaman, L.M., Gower, C.F., Perreault, S.The timing of Proterozoic magmatism in the Pinware terrane of southeast Labrador, easternmost Quebec and northwest Newfoundland.Canadian Journal of Earth Sciences, Vol. 41, 2, February pp. 127-150.Canada, Quebec, LabradorMagmatism, geochronology
DS200712-0836
2006
Perret, E.Perret, E.Color treatment of diamonds and their potential in designer jewelry.Gems & Gemology, 4th International Symposium abstracts, Fall 2006, p.159-60. abstract onlyTechnologyDiamond treatment
DS201912-2790
2019
Perrette, Y.Jacq, K., Giguet-Covex, C., Sabatier, P., Perrette, Y., Fanget, B., Coquin, D., Debret, M., Arnaud, F.High resolution grain size distribution of sediment core with hyperspectral imaging. ( not specific to diamond)Sedimentary Geology, Vol. 393-394, pdfGlobalhyperspectral

Abstract: The study of sediment cores allows for the reconstruction of past climate and environment through physical-chemical analysis. Nevertheless, this interpretation suffers from many drawbacks that can be overcome with the newest technologies. Hyperspectral imaging is one of these and allows a fast, high resolution, and non-destructive analysis of sediment cores. In this study, we use visible and near-infrared hyperspectral imaging to predict particle size fractions and distribution (PSD) at a resolution of 200??m on a previously well-studied sediment core taken from Lake Bourget (Western Alps, France). These predictions agree with previous studies on this core. Then, the PSD was used to estimate sedimentary deposit sources using the PSD unmixing algorithm AnalySize. It permitted estimation of the contribution of five sources (micrite, small and large bio-induced calcite crystals, diatom frustules, detrital particles), which had previously been characterized. The spatial dimension allowed for laminae to be discretized and counted, in agreement with the age-depth model previously established. We then evaluated the particle size and spectral signatures of each of these annual laminae, hence characterizing their physico-chemical composition. These high-resolution data also allowed for estimation of the accumulation rate (cm/year) of each of the main sources in the laminated unit and inferring the trophic status and the presence of instantaneous events of the lake.
DS201811-2599
2015
Perretti, A.Perretti, A., Bieri, W.Flying into the heart of the Colombian emerald mining region.InColor, December pp. 32-43South America, Colombiaemeralds
DS201112-0099
2011
PerrilatBoulard, E., Menguyy, Auzende, Benzerara, Bureau, Antonangeli, Corgne, Morard, Siebert, Perrilat, GuyotExperimental investigation of the stability of Fe rich carbonates in the lower mantle.Goldschmidt Conference 2011, abstract p.561.MantleCarbon reduced.... diamonds
DS2003-1067
2003
Perrilat, J.P.Perrilat, J.P., Daniel, I., Lardeaux, J.M., Cardon, H.Kinetics of the coesite quartz transition: application to the exhumation of ultrahighJournal of Petrology, Vol. 44, 4, pp. 773-88.GlobalUHP
DS200412-1529
2003
Perrilat, J.P.Perrilat, J.P., Daniel, I., Lardeaux, J.M., Cardon, H.Kinetics of the coesite quartz transition: application to the exhumation of ultrahigh pressure rocks.Journal of Petrology, Vol. 44, 4, pp. 773-88.TechnologyUHP
DS200412-1530
2004
Perrillat, J.P.Perrillat, J.P., Ricolleau, A., Daniel, I., Fiquet, G., Mezouar, M., Cardon, H.Phase transformations of MORB in the lower mantle.Lithos, ABSTRACTS only, Vol. 73, p. S87. abstractMantleSubduction
DS200412-1664
2004
Perrillat, J.P.Ricolleau, A., Perrillat, J.P., Fiquet, G., Menguy, N., Daniel, I., Addad, A., Vanni, C.The fate of subducted basaltic crust in the Earth's lower mantle: an experimental petrological study.Lithos, ABSTRACTS only, Vol. 73, p. S93. abstractMantleSubduction
DS200612-1077
2006
Perrillat, J.P.Perrillat, J.P., Ricolleau, A., Daniel, I., Fiquet, G., Mezouar, M., Guignot, N., Cardon, H.Phase transformations of subducted basaltic crust in the upmost lower mantle.Physics of the Earth and Planetary Interiors, Vol. 157, 1-2, pp. 139-149.MantleUHP, subduction
DS201602-0229
2016
Perrillat, J.P.Perrillat, J.P., Chollet, M., Durand, S., van de Moortele, B., Chambat, F., Mezouar, M., Daniel, I.Kinetics of the olivine-ring woodite transformation and seismic attentuation in the Earth's mantle transition zone.Earth and Planetary Science Letters, Vol. 433, pp. 360-369.MantleGeophysics - seismics

Abstract: In regions of the mantle where multi-phases coexist like at the olivine-wadsleyite-ringwoodite transitions, the stress induced by the seismic waves may drive a mineralogical reaction between the low to high pressure phases, a possible source of dissipation. In such a situation, the amount of attenuation critically depends on the timescale for the phase transformations to reach equilibrium relative to the period of the seismic wave. Here we report synchrotron-based measurements of the kinetics of the olivine to ringwoodite transformation at pressure-temperature conditions of the co-stability loop, for iron-rich olivine compositions. Both microstructural and kinetic data suggest that the transformation rates are controlled by growth processes after the early saturation of nucleation sites along olivine grain boundaries. Transformation-time data show an increase of reaction rates with temperature and iron content, and have been fitted to a rate equation for interface-controlled transformation: G=k0?T?exp?[n?XFa]?exp?[?(?Ha+PV?)/RT]×[1?exp?(?Gr/RT)]G=k0?T?exp?[n?XFa]?exp?[?(?Ha+PV?)/RT]×[1?exp?(?Gr/RT)], where XFaXFa is the fayalite fraction, the exponential factor n=9.7n=9.7, View the MathML sourceln?k0=?9.1 ms?1. View the MathML sourceXFa?1 and ?Ha=199 kJ/mol?Ha=199 kJ/mol, assuming V?=0 cm3/molV?=0 cm3/mol. Including these new kinetic results in a micro-mechanical model of a two-phase loop (Ricard et al., 2009), we predict View the MathML sourceQK?1 and View the MathML sourceQ??1 significantly higher than the PREM values for both body waves and normal modes. This attests that the olivine-wadsleyite transition can significantly contribute to the attenuation of the Earth's mantle transition zone.
DS201112-0909
2011
Perrillat, J-P.Sanloup, C., Van Westrenen, W., Dasgupta, R., Maynard-Casely, H., Perrillat, J-P.Compressability change in iron-rich melt and implications for core formation models.Earth and Planetary Science Letters, Vol. 306, 1-2, pp. 118-122.MantleMelting
DS201810-2364
2018
Perrin, A.Perrin, A., Goes, S., Prytulak, J., Rondenay, S., Davies, D.R.Mantle wedge temperatures and their potential relation to volcanic arc location.Earth and Planetary Science Letters, Vol. 501, pp. 67-77.Mantlesubduction

Abstract: The mechanisms underpinning the formation of a focused volcanic arc above subduction zones are debated. Suggestions include controls by: (i) where the subducting plate releases water, lowering the solidus in the overlying mantle wedge; (ii) the location where the mantle wedge melts to the highest degree; and (iii) a limit on melt formation and migration imposed by the cool shallow corner of the wedge. Here, we evaluate these three proposed mechanisms using a set of kinematically-driven 2D thermo-mechanical mantle-wedge models in which subduction velocity, slab dip and age, overriding-plate thickness and the depth of decoupling between the two plates are systematically varied. All mechanisms predict, on the basis of model geometry, that the arc-trench distance, D, decreases strongly with increasing dip, consistent with the negative D-dip correlations found in global subduction data. Model trends of sub-arc slab depth, H, with dip are positive if H is wedge-temperature controlled and overriding-plate thickness does not exceed the decoupling depth by more than 50 km, and negative if H is slab-temperature controlled. Observed global H-dip trends are overall positive. With increasing overriding plate thickness, the position of maximum melting shifts to smaller H and D, while the position of the trenchward limit of the melt zone, controlled by the wedge's cold corner, shifts to larger H and D, similar to the trend in the data for oceanic subduction zones. Thus, the limit imposed by the wedge corner on melting and melt migration seems to exert the first-order control on arc position.
DS200712-0837
2006
Perrin, E.Perrin, E.Defeating the bling..... House of Van Cleef & Arpels.Gems & Gemology, 4th International Symposium abstracts, Fall 2006, p.49-50. abstract onlyGlobalBranding
DS1988-0540
1988
Perrin, M.Perrin, M., Prevot, M.Uncertainties about the Proterozoic and Paleozoic polar wanderpath Of the West African craton and Gondwana: evidence for successive remagnetizationeventsEarth and Planetary Science Letters, Vol. 88, No. 3-4, May pp. 337-347West AfricaBlank
DS1996-0777
1996
Perrin, M.Kosterov, A.A., Perrin, M.Paleomagnetism of the Lesotho basalt, southern AfricaEarth and Plan. Sci. Letters, Vol. 139, pp. 63-78South AfricaKaroo Igneous Province, Polar wandering APW.
DS2001-0978
2001
Perrin, M.Riisager, J., Perrin, M., Riisage, P., Vandamme, D.Paleomagnetic results and paleointensity of Late Cretaceous Madagascan basaltJournal of African Earth Science, Vol. 32, No. 3, Apr. pp. 503-18.MadagascarBasalts
DS202002-0186
2020
Perrin, M.Garcia, L.F., Abel, M., Perrin, M., dos Santis Alvarenga, R.The GeoCore ontology: a core ontology for general use in geology.Computers and Geosciences, Vol. 135, 104387 9p. PdfGlobalGeoCore

Abstract: Domain ontologies assume the role of representing, in a formal way, a consensual knowledge of a community over a domain. This task is especially difficult in a wide domain like Geology, which is composed of diversified science resting on a large variety of conceptual models that were developed over time. The meaning of the concepts used by the various professionals often depends on the particular vision that they have of a domain according to their background and working habits. Ontology development in Geology thus necessitates a drastic elucidation of the concepts and vocabulary used by geologists. This article intends to contribute to solving these difficulties by proposing a core ontology named GeoCore Ontology resting on the BFO top ontology, specially designed for describing scientific fields. GeoCore Ontology contains well-founded definitions of a limited set of general concepts within the Geology field that are currently considered by all geologists whatever their skill. It allows modelers to separately consider a geological object, the substance that constitutes it, the boundaries that limit it and the internal arrangement of the matter inside it. The core ontology also allows the description of the existentially dependent qualities attached to a geological object and the geological process that generated it in a particular geological age. This small set of formally defined and described concepts combined with concepts from BFO provides a backbone for deriving by subsumption more specialized geological concepts and also constitutes a baseline for integrating different existent domain ontologies within the Geology domain. The GeoCore ontology and the methodology that we used for building it, provide solutions for unveiling major misunderstanding regarding the concepts that are commonly used for formulating geological interpretations. This will facilitate the communication of this information to external Geology users and its integration in domain applications.
DS1989-0045
1989
Perrin, T.Audino, N., Perrin, T., Borbely, J.A corporate online database: perspectives on anin-house text retrieval system Part 1. Design and implementationDatabase, Vol. 12, No. 3, June pp. 30-35. Database # 17936GlobalComputer, Program - in house text retrieval
DS1989-1199
1989
Perring, C.S.Perring, C.S., Rock, N.M.S., Golding, S.D., Roberts, D.E.Criteria for the recognition of metamorphosed or altered lamprophyres: acase study from the Archean of Kambalda Western AustraliaPrecambrian Research, Vol. 43, nol 2, pp. 215-237AustraliaCanada, Zimbabwe, Tanzania, Classification -Lamprophy, Geochemistry
DS1991-1335
1991
Perring, C.S.Perring, C.S., Rock, N.M.S.Relationships between calc-alkaline acidic and basic (mantle derived)magmas in Late Archean composite dykes, Kambalda Goldfield, western AustraliaPrecambrian Research, Vol. 52, pp. 245-273AustraliaAlkaline magmas, Deposit -Kambalda Goldfield
DS1994-1750
1994
Perring, C.S.Taylor, W.R., Rock, N.M.S., Groves, D.I., Perring, C.S., GoldingGeochemistry of Archean shoshonitic lamprophyres from the Yilgarn Block: gold abundance and association with gold mineralizationApplied Geochemistry, Vol. 9, pp. 197-222AustraliaAlkaline rocks -Shoshonite, Lamprophyre
DS1995-1485
1995
Perring, C.S.Perring, C.S., Barnes, S.J., Hill, R.E.T.The physical volcanology of Archean komatiite sequences from Forrestania, Southern Cross Province, Western AusLithos, Vol. 34, No. 1-3, Jan. pp. 189-208AustraliaKomatiites, Archean
DS1996-1111
1996
Perring, C.S.Perring, C.S., Barnes, S.J., Hill, R.E.T.Geochemistry of komatiites from Forrestania,Southern Cross Province:evidence for crustal contaminationLithos, Vol. 37, No. 2/3, April pp. 181-198AustraliaGeochemistry, Komatiites -Forrestania
DS1981-0335
1981
Perring, R.Perring, R., Turley, S., Geopeko ltd, DESIGN AND CONSTRUCTION P.El 2411, El 2412, El 2417, El 2418, El 2419, El 2420, El 242Northern Territory Open File., No. CR 82-124, UNPUBL.Australia, Northern TerritoryGeochemistry, Prospecting, Stream Sediment Sampling, Assay
DS1982-0492
1982
Perring, R.Perring, R., Turley, S.El 2411, El 2412, El 2417, El 2504, El 2513, El 2514, El 2515, El 2584, and El 2585.. Heavy Mineral Seperation and Geochemical Analysis, 1980-1981.Northern Territory Geological Survey Open File Report, No. CR 82/124, 2978 TABLES.Australia, Northern TerritoryProspecting, Sampling, Geochemistry
DS1982-0493
1982
Perring, R.Perring, R., Turley, S., Geopeko ltd., DESIGN AND CONSTUCTION P.El 2417, El 2418, El 2419, El 2420, El 2421, El 2513, El 251Northern Territory Open File., No. CR 82-119, 12P. UNPUBL.Australia, Northern TerritoryGeophysics, Geochemistry, Prospecting, Stream Sediment Sampling
DS201212-0573
2012
Perrit, S.Preston, R.F., Wyatt, B., Perrit, S.Lithospheric structure beneath the Cretaceous Orapa kimberlite field, Botswana: 4D lithosphere imaging using garnet indicator mineral chemistry.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractAfrica, BotswanaDeposit - Orapa
DS201212-0339
2012
Perritt, S.Jelsma, H.,Krishnan, S.U., Perritt, S.,Kumar, M., Preston, R., Winter, F., Lemotlo, L., Costa, J., Van der Linde, G., Facatino, M., Posser, A., Wallace, C., Henning, A., Joy, S., Chinn, I., Armstrong, R., Phillips, D.Kimberlites from central Angola: a case stidy of exploration findings.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractAfrica, AngolaOverview of kimberlites
DS201412-0427
2013
Perritt, S.Jelsma, H., Krishnan, U., Perritt, S., Preston, R., Winter, F., Lemotlo, L., van der Linde, G., Armstrong, R., Phillips, D., Joy, S., Costa, J., Facatino, M., Posser, A., Kumar, M., Wallace, C., Chinn, I., Henning, A.Kimberlites from central Angola: a case study of exploration findings.Proceedings of the 10th. International Kimberlite Conference, Vol. 2, pp. 173-190.Africa, AngolaExploration - kimberlites
DS201412-0678
2014
Perritt, S.Perritt, S.A record of structural and chemical processes in the mantle preserved in a suite of deformed garnet megacrysts from Monteleo kimberlte, South Africa.ima2014.co.za, AbstractAfrica, South AfricaDeposit - Monteleo
DS201601-0038
2015
Perritt, S.Perritt, S., Preston, R., Viljoen, F., Van Der Linde, G.Morphology, micro-structure and chemistry of a deformed garnet megacryst suite from Montelo kimberlite, Free State Province, South Africa.South African Journal of Geology, Vol. 118, 4, pp. 439-454.Africa, South AfricaDeposit - Montelo
DS201905-1062
2019
Perritt, S.Nestola, F., Jacob, D.E., Pamato, M.G., Pasqualatto, L., Oliveira, B., Greene, S., Perritt, S., Chinn, I., Milani, S., Kueter, N., Sgreva, N., Nimis, P., Secco, L., Harris, J.W.Protogenetic garnet inclusions and the age of diamonds.Geology, doi.10.1130/G45781.1Mantlediamond inclusions

Abstract: Diamonds are the deepest accessible “fragments” of Earth, providing records of deep geological processes. Absolute ages for diamond formation are crucial to place these records in the correct time context. Diamond ages are typically determined by dating inclusions, assuming that they were formed simultaneously with their hosts. One of the most widely used mineral inclusions for dating diamond is garnet, which is amenable to Sm-Nd geochronology and is common in lithospheric diamonds. By investigating worldwide garnet-bearing diamonds, we provide crystallographic evidence that garnet inclusions that were previously considered to be syngenetic may instead be protogenetic, i.e., they were formed before the host diamond, raising doubts about the real significance of many reported diamond “ages.” Diffusion modeling at relevant pressures and temperatures, however, demonstrates that isotopic resetting would generally occur over geologically short time scales. Therefore, despite protogenicity, the majority of garnet-based ages should effectively correspond to the time of diamond formation. On the other hand, our results indicate that use of large garnet inclusions (e.g., >100 ?m) and diamond hosts formed at temperatures lower than ?1000 °C is not recommended for diamond age determinations.
DS202008-1427
2020
Perritt, S.Nimis, P., Preston, R., Perritt, S., Chinn, I.Is diamond depth distribution systematic?Goldschmidt 2020, 1p. AbstractAfrica, South Africageobarometry

Abstract: The thermobarometric analysis of inclusions in lithospheric diamonds indicates that they originated from a wide range of depths, with a global mode at ca. 170±15 km [1]. Studies based on diamond depth distribution at global scale, however, cannot clarify if this mode reflects a real concentration of diamonds, preferential sampling of materials from this level by rising kimberlites, or even a statistical distribution within the hard limits imposed by diamond stability, lithosphere thickness, and mantle adiabat under typical cratonic thermal regimes. We addressed this problem by comparing depth distributions for peridotitic diamonds from the three localities that have been the most prolific for diamond geobarometry (Cullinan, Kimberley and Voorspoed, South Africa) with those of mantle xenocrysts from the same kimberlite sources. P-T estimates indicate that the diamonds were formed at T higher, equal or lower than the ambient geotherm. They may record old mantle thermal regimes or local thermal perturbations related to infiltration of parent fluids or melts. Nonetheless, the diamonds show similar depth distributions for different localities, with a distinct mode at ?175 ?? 10 km. The similarity of these distributions with that calculated for peridotitic diamonds worldwide, as well as the lack of systematic correlation with kimberlite sampling efficiency as recorded by mantle xenocrysts, suggests that this mode has genetic significance. Based on observed depth distributions at both local and global scale and on thermodynamic modeling of COH fluids, diamond-forming processes are predicted to become less efficient with decreasing depth from at least ?160 km. In addition, diamond endowment near the base of the lithosphere may be negatively affected by infiltration of carbon-undersaturated melts. Considering the poor correlation between diamond and xenocryst depth distributions in single kimberlites or kimberlite clusters, even limited xenocryst records from diamond favorable depths (especially the 160-190 km interval) may correspond to significant diamond potential.
DS201806-1216
2018
Perritt, S.H.Chinn, I.L., Perritt, S.H., Stiefenhofer, J., Stern, R.A.Diamonds from Orapa mine show a clear subduction signature in SIMS stable isotope data.Mineralogy and Petrology, in press available, 11p.Africa, Botswanadeposit - Orapa

Abstract: Spatially resolved analyses reveal considerable isotopic heterogeneity within and among diamonds ranging in size from 0.15 to 4.75 mm from the Orapa Mine, Botswana. The isotopic data are interpreted in conjunction with nitrogen aggregation state data and growth zone relationships from cathodoluminescence images. The integrated information confirms that a distinct diamond growth event (with low IaAB nitrogen aggregation states, moderately high nitrogen contents and ?13C and ?15N values compatible with average mantle values) is younger than the dominant population(s) of Type IaAB diamonds and cores of composite diamonds with more negative and positive ?13C and ?15N values, respectively. A significant proportion of the older diamond generation has high nitrogen contents, well outside the limit sector relationship, and these diamonds are likely to reflect derivation from subducted organic matter. Diamonds with low ?13C values combined with high nitrogen contents and positive ?15N values have not been previously widely recognised, even in studies of diamonds from Orapa. This may have been caused by prior analytical bias towards inclusion-bearing diamonds that are not necessarily representative of the entire range of diamond populations, and because of average measurements from heterogeneous diamonds measured by bulk combustion methods. Two distinct low nitrogen/Type II microdiamond populations were recognised that do not appear to continue into the macrodiamond sizes in the samples studied. Other populations, e.g. those containing residual singly-substituted nitrogen defects, range in size from small microdiamonds to large macrodiamonds. The total diamond content of the Orapa kimberlite thus reflects a complex assortment of multiple diamond populations.
DS201807-1484
2018
Perritt, S.H.Chinn, I.L., Perritt, S.H.The art and science of diamond analysis, and what the results can tell us. PresentationSAIMM Diamonds - source to use 2018 Conference 'thriving in changing times'. June 11-13., pp. 155-160.GlobalDiamond analyses, populations, economics
DS201808-1732
2018
Perritt, S.H.Chinn, I.L, Perritt, S.H.The art and science of diamond analysis, and what the results can tell usSAIMM Diamonds - source to use 2018 Conference 'thriving in changing times'. June 11-13., 18 ppts.Globalpopulation, economics
DS201812-2897
2018
Perritt, S.H.Viljoen, K.S., Perritt, S.H., Chinn, I.L.An unusual suite of eclogitic, websteritic and transitional websteritic-lherzolitic diamonds from the Voorspoed kimberlite in South Africa: mineral inclusions and infrared characteristics.Lithos, Vol. 320-321, pp. 416-434.Africa, South Africadeposit - Voorspoed

Abstract: A study of the morphology, mineral inclusions, nitrogen content, and nitrogen aggregation state of diamonds from the Voorspoed kimberlite, was conducted. The diamonds are characterised by a highly unusual inclusion mineral paragenesis dominated by eclogitic and transitional websteritic-lherzolitic inclusions along with related websteritic inclusions, while a comparatively minor harzburgitic diamond inclusion suite account for the remainder. This differs substantially from many of the diamond populations in kimberlites on the Kaapvaal Craton where a harzburgitic inclusion paragenesis predominates. Only in the case of the Orapa kimberlite in Botswana has a similar diamond inclusion suite been encountered before, although in that instance an eclogitic and websteritic inclusion suite predominate. Calculated garnet-clinopyroxene equilibration temperatures, at an assumed pressure of 50?kbar, range from 1040 °C to 1296?°C. Temperatures of 1114?°C to 1348?°C, at 50?kbar, are calculated for lamellar orthopyroxene-clinopyroxene intergrowths. ‘Reconstituted’ pyroxenes mathematically reconstructed from the lamellar orthopyroxene-clinopyroxene intergrowths produce temperatures of 1238?°C to 1416?°C, suggesting that the lithosphere cooled by at least 100?°C after diamond crystallisation. Nitrogen contents and nitrogen aggregation states of whole diamonds range from below the detection limit (~10?ppm) to 1442 atomic ppm (average 167 atomic ppm), and up to 97% of the highly aggregated ‘B' component (average 65%), respectively. The elevated aggregation state of the nitrogen in the diamonds from Voorspoed, coupled with a high level of platelet degradation in many of the diamonds analysed, relative to a world-wide database, is unusual, but broadly comparable to diamonds from kimberlites occurring in craton margin settings, such as Argyle and Venetia. Diamond inclusion thermobarometry, as well as the elevated nitrogen aggregation states of the diamonds (coupled with the evidence for platelet degradation in the diamonds) are indicative of a diamond crystallisation event associated with a transient thermal pulse, as well as associated deformation of the mantle containing the diamonds. The websteritic and the transitional websteritic-lherzolitic mantle source rocks of the Voorspoed diamonds likely formed through melt infiltration into mantle peridotite, possibly in the reaction envelope surrounding an ascending mantle plume. In order to account for the unusually low abundance of harzburgitic diamonds at Voorspoed, it is postulated that a primary, pre-existing suite of harzburgitic diamonds which have crystallised in the Mesoarchaean, was destroyed through heating and oxidation during the passage of magmas associated with the Ventersdorp large igneous province at 2.72?Ga, and which was subsequently followed by the crystallisation of a younger eclogitic and transitional websteritic-lherzolitic suite of diamonds.
DS202009-1647
2020
Perritt, S.H.Nimis, P., Preston, R., Perritt, S.H., Chinn, I.L.Diamond's depth distribution systematics. ( geotherm)Lithos, 10.1016/j.lithos. 2020.105729 15p. PdfAfrica, South Africadeposit - Cullinan, Kimberley, Voorspoed

Abstract: The thermobarometric analysis of inclusions in lithospheric diamonds has shown that these diamonds may originate from a wide range of depths, with a global mode at ~175 ± 15 km. Studies based on diamond depth distribution at global scale, however, cannot clarify if this mode reflects a real concentration of diamonds, preferential sampling of materials from this level by ascending kimberlites, or simply a statistical distribution within the hard limits imposed by diamond stability, lithosphere thickness and mantle adiabat under typical cratonic thermal regimes. We addressed this problem by comparing depth distributions for peridotitic diamonds from the three localities that have been the most prolific for diamond geobarometry (Cullinan, Kimberley and Voorspoed, South Africa) with those of mantle xenocrysts from the same kimberlite sources. The revised P-T estimates indicate that the diamonds were formed at T higher, equal or lower than the ambient geotherm recorded by the xenocrysts. These conditions may represent old mantle thermal regimes or local thermal perturbations related to infiltration of parental fluids or melts. Nonetheless, the studied diamonds show similar depth distributions for the different localities, with a distinct mode at ?180 ± 10 km. The similarity of these distributions with that calculated for peridotitic diamonds worldwide, as well as the lack of systematic correlation with kimberlite sampling efficiency as recorded by mantle xenocrysts, suggests that this mode has genetic significance. Based on observed depth distributions and thermodynamic modeling of COH fluids, diamond-forming processes are predicted to become less efficient with decreasing depth from at least ?165 km. In addition, diamond endowment near the base of the lithosphere may be negatively affected by infiltration of carbon-undersaturated melts or fluids after diamond formation. Considering the poor correlation between diamond and xenocryst depth distributions in single kimberlites or kimberlite clusters, even limited xenocryst records from diamond favorable depths (especially from the 160-190 km interval) may correspond to significant diamond potential.
DS202203-0344
2022
Perritt, S.H.Fedortchouk, Y., Chinn, I., Zhang, Z., Stern, R.A., Perritt, S.H., Li, Z.Diamond-destructive mantle metasomatism: evidence from the internal and external textures of diamonds and their nitrogen defects.Lithos, Vol. 414-415, 19p. Mantlemetasomatism

Abstract: Metasomatic processes modify the composition of the subcratonic lithospheric mantle and can either form or destroy diamonds. The composition of these metasomatic agents is uncertain and has been mostly deduced from chemical zonation and overprints recorded by associated mantle silicates. Diamonds experience partial dissolution (resorption) during their residence in the mantle due to mantle metasomatism and later during their ascent in kimberlite magma. Diamonds, enclosed inside mantle xenoliths during the whole duration of ascent in kimberlite magma, can preserve their pre-kimberlite surface features, which record the last diamond-destructive metasomatic event to have occurred in the mantle. The geometry of diamond dissolution features acquired during mantle storage can provide information about diamond-destructive metasomatic events in the mantle. Diamond samples recovered from inside mantle xenoliths are extremely rare and mostly limited to eclogitic lithology, which suggests that variable resistance of different mantle lithologies to disintegration in kimberlite magma may affect representativity of these sample. Here we use whole diamond populations from exploration parcels and apply our earlier developed set of criteria to distinguish between kimberlitic and pre-kimberlitic surface features on diamonds. The study used diamonds (<1 to 4.5 mm size) from eight kimberlites in three localities: Orapa cluster, Botswana (BK1, AK15, and AK1 kimberlites), Ekati Mine, Northwest Territories, Canada (Grizzly, Leslie, Koala, and Misery kimberlites), and Snap Lake kimberlite dyke, Northwest Territories, Canada. The host kimberlites cover seven different volcaniclastic and coherent kimberlite lithologies, and our previous studies demonstrated a correlation between the style of kimberlitic resorption on diamonds and the host kimberlite lithology for these samples. From the total of 3256 studied diamonds, we identified 534 diamonds with pre-kimberlite surface textures. These pre-kimberlite surface textures display six distinct types, which are present in all the studied diamond parcels regardless of their geographic locality and host kimberlite lithology. The relative proportions of these types depend on the geographic locality showing linkage to a specific mantle source. We examined the relationship between the surface features on diamonds, their growth patterns revealed in cathodoluminescence (CL) images, the content and aggregation of nitrogen defects using Fourier transform infrared spectroscopy (FTIR), and nitrogen content in specific growth zones of diamonds obtained using secondary ion mass spectrometry (SIMS) for 82 Ekati diamonds. Our data show that growth step-faces develop on diamonds with complex multi-crystal cores, whereas flat-faced octahedra with simple oscillatory-zoned growth patterns derive from single growth events. Initial stages of dissolution affecting only outer growth zones develop simple serrate laminae on diamonds, while more extensive dissolution exposes more complex growth zones developing various shapes of laminae and etch features (trigons and irregular asperities). The effect of internal growth patterns on dissolution features is more profound during pre-kimberlitic than kimberlite-related resorption likely due to the greater role of defects in diamond dissolution at mantle conditions. Comparison with the results of diamond dissolution experiments shows that metasomatism by C-O-H fluid is not destructive to diamond, while carbonate-silicate melt-driven metasomatism causes diamond dissolution. Continuous change in the silicate content of silicate?carbonate melts and temperature variations within 200 °C can explain all pre-kimberlite dissolution features observed in this study. Similar pre-kimberlite dissolution features on diamonds from both the Zimbabwe and Slave cratons suggests that these metasomatic processes are widespread and affected the mantle below the eight studied kimberlites.
DS1992-1186
1992
Perron, A.Perron, A.Kimberlite dyke on Buffonta/Silverside propertyPromotion material, 2 pg. outline about kimberlites and 2 press releasesOntarioNews item, Garrison Twp. Buffonta
DS1990-1174
1990
Perron, B.Perron, B.Etude structurale des dykes de lamprophyre et de carbonatites associes au complex alcalin de St. Honore.University of du Quebec a Chicoutimi, 31p.QuebecDike - lamprophyre
DS2003-0914
2003
Perron, G.McGaughey, W.J., Perron, G., Bellefleur, G.Downhole seismic imaging technology for deep mineral exploration. (mentions VictorOntario Exploration and Geoscience Symposium, Dec. 8,9,10th., Abstracts p. 16-17. (1/4p.)Ontario, AttawapiskatGeophysics - seismic DS
DS200412-1271
2003
Perron, G.McGaughey, W.J., Perron, G., Bellefleur, G.Downhole seismic imaging technology for deep mineral exploration. (mentions Victor pipe)Ontario Exploration and Geoscience Symposium, Dec. 8,9,10th., Abstracts p. 16-17. (1/4p.)Canada, Ontario, Attawapiskat, James Bay LowlandsGeophysics - seismic DS
DS200612-1350
2006
Perron, G.Sprague, K., De Kemp, E., Wong, W., McGaughey, J., Perron, G., Barrie, T.Spatial targeting using queries in a 3 D GIS environment with application to mineral exploration.Computers & Geosciences, Vol.32, 3, pp. 396-418.TechnologyComputer - programs
DS200712-0066
2005
Perron, G.Bellefleur, G., Matthews, L., Roberts,B., McMonnies, B., Salisbury, M., Snyder, D., Perron, G., McGaughty, J.Downhole seismic imaging of the Victor kimberlite, James Bay Lowlands, Ontario: a feasibility study.Geological Survey of Canada Current Research, 2005- C1, 7p.Canada, OntarioGeophysics - seismics
DS201112-0090
2011
Perron, T.Blackburn, T., Bowring, S., Perron, T., Mahan, K., Dudas, F.A long term record of continental lithosphere exhumation via U-Pb thermochronology of the lower crust.Goldschmidt Conference 2011, abstract p.532.United States, MontanaCraton, keels
DS200412-0353
2004
Perrot, R.Contrucci, I., Klingelhofer, J., Perrot, R., Bartolome, M.A., Gutscher, M., Sahabi, J., Malod, J.P.The crustal structure of the NW Moroccan continental margin from wide angle reflection seismic data.Geophysical Journal International, Vol. 159, 1, pp. 117-128.Africa, MoroccoGeophysics - seismics, Tectonics
DS201509-0403
2015
Perrouty, S.Jessell, M., Santoul, J., Baratoux, L., Youbi, N., Ernst, R.E., Metelka, V., Miller, J., Perrouty, S.An updated map of West African mafic dykes.Journal of African Earth Sciences, in press availableAfrica, West AfricaGeophysics - magnetics

Abstract: Studies of mafic dyke swarms may simultaneously provide information on the mechanical, geochemical, geochronological and magnetic environments at the time of their formation. The mafic intrusive history of different cratons can also be potentially used to unravel their assembly into their current configuration. The identification and classification of dykes is a first step to all these studies. Fortunately, even in regions with poor outcrop, we can use the strong magnetic response of mafic dykes to identify and map their extent. In West Africa the first maps of mafic dyke distribution were made over 40 years ago, but there are still large areas where there are almost no published data. In this paper we present a significantly updated map of mafic dykes for the West Africa Craton based in large part on new interpretations of the regional airborne magnetic database. This map includes the locations of over three thousand dykes across the craton, which locally shows several orientation clusters that provide a minimum estimate for the total number of dyke swarms in this region. Whilst we will have to wait until systematic dating of the different swarms is completed, we can demonstrate that there is a long and complex history of mafic magmatism across the craton, with up to 26 distinct dyke swarms mapped based according to their orientation. The mapping and dating of these swarms will provide key constraints on the assembly of the fragments that make up the modern continents.
DS201902-0261
2019
Perrouty, S.Baratoux, L., Soderlund, U., Ernst, R.E., de Roever, E., Jessell, M.W., Kamo, S., Naba, S., Perrouty, S., Metelka, V., Yatte, D., Grenholm, M., Diallo, D.P., Ndiaye, P.M., Dioh, E., Cournede, C., Benoit, M., Baratoux, D., Youbi, N., Rousse, S., BendaoudNew U-Pb baddeleyite ages of mafic dyke swarms of the West African and Amazonian cratons: implication for their configuration in supercontinents through time.Dyke Swarms of the World: a modern perspective, Srivastava et al. eds. Springer , pp. 263-314.Africa, West Africa, South Americageochronology

Abstract: Eight different generations of dolerite dykes crosscutting the Paleoproterozoic basement in West Africa and one in South America were dated using the high precision U-Pb TIMS method on baddeleyite. Some of the individual dykes reach over 300 km in length and they are considered parts of much larger systems of mafic dyke swarms representing the plumbing systems for large igneous provinces (LIPs). The new U-Pb ages obtained for the investigated swarms in the southern West African Craton (WAC) are the following (oldest to youngest): 1791?±?3 Ma for the N010° Libiri swarm, 1764?±?4 Ma for the N035° Kédougou swarm, 1575?±?5 for the N100° Korsimoro swarm, ~1525-1529 Ma for the N130° Essakane swarm, 1521?±?3 Ma for the N90° Sambarabougou swarm, 915?±?7 Ma for the N070° Oda swarm, 867?±?16 Ma for the N355° Manso swarm, 202?±?5 Ma and 198?±?16 Ma for the N040° Hounde swarm, and 200?±?3 Ma for the sills in the Taoudeni basin. The last ones are related to the Central Atlantic Magmatic Province (CAMP) event. The Hounde swarm is oblique to the dominant radiating CAMP swarm and may be linked with the similar-trending elongate Kakoulima intrusion in Guinea. In addition, the N150° Käyser swarm (Amazonian craton, South America) is dated at 1528?±?2 Ma, providing a robust match with the Essakane swarm in a standard Amazonia-West African craton reconstruction, and resulting in a combined linear swarm >1500 km by >1500 km in extent. The Precambrian LIP barcode ages of c. 1790, 1765-1750, 1575, 1520, 915. 870 Ma for the WAC are compared with the global LIP record to identify possible matches on other crustal blocks, with reconstruction implications. These results contribute to the refinement of the magmatic ‘barcode’ for the West African and Amazonian cratons, representing the first steps towards plausible global paleogeographic reconstructions involving the West African and Amazonian cratons.
DS202106-0950
2021
Perrouty, S.Le Pape, F., Jones, A.G., Jessell, M.W., Hogg, C., Siebenaller, L., Perrouty, S., Tour, A., Oiuya, P., Boren, G.The nature pf the southern West Africa craton lithosphere inferred from its electrical resistivity.Precambrian Research, Vol. 358, 106190, 15p. Pdf Africageophysics

Abstract: The West-African craton is defined by a combination of Archean and Palaeoproterozoic rocks that stabilised at ~2 Ga towards the end of the Paleoproterozoic Eburnean Orogeny, and therefore may reflect the transition from Archean to modern tectonic processes. Exploring its present lithospheric architecture aids further understanding of not only the craton’s stability through its history but also its formation. We investigate the lithospheric structure of the craton through analysing and modelling magnetotelluric (MT) data from a 500-km-long east-west profile in northern Ghana and southern Burkina Faso crossing part of the Baoulé-Mossi Domain and reaching the Volta Basin in the south-eastern part of the craton. Although the MT stations are along a 2D profile, due to the complexity of the structures characterising the area, 3D resistivity modelling of the data is performed to obtain insights on the thermal signature and composition of the subcontinental lithosphere beneath the area. The thermal structure and water content estimates from different resistivity models highlight a strong dependence on the starting model in the 3D inversions, but still enable us to put constraints on the deep structure of the craton. The present?day thermal lithosphere?asthenosphere boundary (LAB) depth is estimated to be at least 250 km beneath the Baoulé-Mossi domain. The area likely transitions from a cold and thick lithosphere with relatively low water content into thinner, more fertile lithosphere below the Volta Basin. Although the inferred amount of water could be explained by Paleoproterozoic subduction processes involved in the formation of the Baoulé-Mossi domain, later enrichment of the lithosphere cannot be excluded.
DS1998-1153
1998
Perry, A.Perry, A., Gurmendi, A.Reasonable environmental regulations and controls in Latin America for sustainable economic developmentSociety for Mining, Metallurgy and Exploration (SME) Preprint, No. 98-15Latin AmericaLegal, Environmental regulations
DS201012-0574
2010
Perry, C.Perry, C., Rosieanu, C., Maraeschal, J-C., Jaupart, C.Thermal regime of the lithosphere in the Canadian shield.Canadian Journal of Earth Sciences, Vol. 47, 4, pp. 389-408.Canada, Northwest TerritoriesGeothermometry
DS1980-0117
1980
Perry, E.C.JR.Ehrenberg, S.N., Ahmad, S.N., Perry, E.C.JR.Oxygen Isotopic Compositions of Garnet Granulites from Colorado Plateau Diatremes.Eos, Vol. 61, No. 17, APRIL 22ND. P. 387.United States, Colorado PlateauBlank
DS1991-0057
1991
Perry, F.V.Baldridge, W.S., Perry, F.V., Vaniman, D.T., et al.Middle to late Cenozoic magmatism of the southeastern Colorado Plateau And central Rio Grande rift ( New Mexico and Arizona): a model for continentalriftingTectonophysics, Vol. 197, No. 2-4, November pp. 327-354New Mexico, Arizona, Colorado PlateauTectonics, Rift systems
DS1993-0918
1993
Perry, F.V.Livaccari, R.F., Perry, F.V.Isotopic evidence for preservation of Cordilleran lithospheric mantle during the Sevier-Laramide orogeny, western United StatesGeology, Vol. 21, No. 8, August pp. 719-722CordilleraGeochronology, Orogeny
DS200612-1458
2006
Perry, F.V.Valentine, G.A., Perry, F.V.Decreasing magmatic footprints of individual volcanoes in a waning basaltic field.Geophysical Research Letters, Vol. 33, 14, L14305.MantleMagmatism
DS2000-0299
2000
Perry, H.K.C.Forte, A.M., Perry, H.K.C.Geodynamics evidence for a chemically depleted continental tectosphereScience, Vol. 290, no, 5498, Dec. 8, pp. 1940-6.MantleGeodynamics - tectonics, Lithosphere
DS2003-1068
2003
Perry, H.K.C.Perry, H.K.C., Forte, A.M., Eaton, F.W.S.Upper mantle thermochemical structure below North America from seismicGeophysical Journal International, Vol. 154, 2, pp. 279-99.MantleGeophysics - seismics, Discontinuity
DS200412-1223
2004
Perry, H.K.C.Maraschal, J.C., Nyblade, A., Perry, H.K.C., Jaupart, C., Bienfait, G.Heat flow and deep lithospheric thermal structure at Lac de Gras Slave Province, Canada.Geophysical Research Letters, Vol. 31, 12, June 28, 10.1029/2004 GLO20133Canada, Northwest TerritoriesGeothermometry
DS200412-1531
2004
Perry, H.K.C.Perry, H.K.C., Forte, A.M., Eaton, D.W.S.Upper mantle thermochemical structure below North America from seismic geodynamic flow models.Geophysical Journal International, Vol. 154, 2, pp. 279-299.Canada, Northwest TerritoriesGeothermometry, geophysics - seismics, discontinuity
DS200512-0846
2004
Perry, H.K.C.Perry, H.K.C., Jaupart, C., Mareschal, J.C., Rolandone, F., Bienfait, G.Heat flow in the Nipigon arm of the Keweenawan Rift, northwestern Ontario, Canada.Geophysical Research Letters, Vol. 31, 15,, L15607, DOI 1029/2004 GL020159Canada, OntarioGeothermometry
DS200612-0866
2006
Perry, H.K.C.Mareschal, J-C., Jaupart, C., Perry, H.K.C.Crustal evolution in North America recorded in heat production.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 12, abstract only.Mantle, North AmericaGeothermometry
DS200612-1078
2006
Perry, H.K.C.Perry, H.K.C., Jaupart, C., Mareschal, J.C., Bienfait, G.Crustal heat production in the Superior Province Canadian Shield and in North America inferred from heat flow data.Journal of Geophysical Research, Vol. 111, B4, B04401.Canada, Ontario, ManitobaGeothermometry
DS200612-1079
2006
Perry, H.K.C.Perry, H.K.C., Jaupart, C., Mareschal, J.C., Shapiro, N.M.Upper mantle velocity temperature conversion and composition determined from seismic refraction and heat flow.Journal of Geophysical Research, Vol. 111, B7 B07301MantleGeophysics - seismics
DS200612-1080
2006
Perry, H.K.C.Perry, H.K.C., Jaupart, C., Mareschal, J.C., Shapiro, N.M.Upper mantle velocity temperature conversion and composition determined from seismic.Journal of Geophysical Research, Vol. 111, B7, July 6, B07301, 14p.Mantle, Canada, OntarioGeophysics - seismics, Superior Province
DS200612-1081
2006
Perry, H.K.C.Perry, H.K.C., Jaupart, C., Mareschal, J-C., Bienfait, G.Crustal heat production in the Superior Province, Canadian Shield, and in North America.Journal of Geophysical Research, Vol. 111, No. B4, B04401Canada, Ontario, Manitoba, Saskatchewan, AlbertaGeothermometry
DS200612-1082
2006
Perry, H.K.C.Perry, H.K.C., Mareschal, J-C., Jaupart, C.Variations of strength and localized deformation in cratons: the 1.9 Ga Kapuskasing Uplift, Superior Province, Canada.Earth and Planetary Science Letters, In press - availableCanada, Ontario, ManitobaGeothermometry, craton, structural zone
DS201012-0575
2010
Perry, H.K.C.Perry, H.K.C., Forte, A.Upper mantle thermochemical structure from seismic geodynamic flow models: constraints from the Lithoprobe initiative.Canadian Journal of Earth Sciences, Vol. 47, 4, pp. 463-484.MantleGeophysics - seismic
DS1983-0512
1983
Perry, L.E.Perry, L.E.Field Trip Crater of Diamonds. America's One Diamond Pipe Is Now an Arkansaw State Park.Rock And Gem., Vol. 13, No. 2, FEBRUARY, PP. 22-25.United States, Gulf Coast, Arkansas, PennsylvaniaBlank
DS1960-0183
1961
Perry, V.D.Perry, V.D.The Significance of Mineralized Breccia PipesMining Engineering, Vol. 13, APRIL, PP. 367-376.South AfricaGeology, Mineralogy, Premier Mine
DS1989-1200
1989
Perry, W.J Jr.Perry, W.J Jr.Tectonic evolution of the Anadarko Basin region, OklahomaUnited States Geological Survey (USGS) Bulletin, No. B 1866-A, pp. A1-A19. $ 1.50GlobalTectonics, mid continent ridge
DS1990-1175
1990
Perry, W.J.Perry, W.J., Agena, W.F.Structural interpretations of the Ouachita frontal zone near HartshorneOklahoma, based on reprocessed seismic reflection dataGeological Society of America (GSA) Annual Meeting, Abstracts, Vol. 22, No. 7, p. A231GlobalTectonics, Geophysics -seismics
DS1988-0541
1988
Perry, W.J. Jr.Perry, W.J. Jr.A review of the geology and petroleum resource potential of the Montana thrust beltUnited States Geological Survey (USGS) Open File, No. 88-0450-C, 43p. $ 6.50MontanaGeology, Review
DS201611-2113
2016
Persano, R.Happe Kazanzu, C., Linol, B., de Wit, M.J., Brown, R., Persano, R., Stuart, F.M.From source to sink in central Gondwana: exhumation of the Precambrian basement rocks of Tanzania and sediment accumulation in the adjacent Congo basin.Tectonics, Vol. 35, 9, pp. 2034-2051.Africa, TanzaniaGeodynamics

Abstract: Apatite fission track (AFT) and (U-Th)/He (AHe) thermochronometry data are reported and used to unravel the exhumation history of crystalline basement rocks from the elevated (>1000?m above sea level) but low-relief Tanzanian Craton. Coeval episodes of sedimentation documented within adjacent Paleozoic to Mesozoic basins of southern Tanzania and the Congo basin of the Democratic Republic of Congo indicate that most of the cooling in the basement rocks in Tanzania was linked to erosion. Basement samples were from an exploration borehole located within the craton and up to 2200?m below surface. Surface samples were also analyzed. AFT dates range between 317?±?33?Ma and 188?±?44?Ma. Alpha (Ft)-corrected AHe dates are between 433?±?24?Ma and 154?±?20?Ma. Modeling of the data reveals two important periods of cooling within the craton: one during the Carboniferous-Triassic (340-220?Ma) and a later, less well constrained episode, during the late Cretaceous. The later exhumation is well detected proximal to the East African Rift (70?Ma). Thermal histories combined with the estimated geothermal gradient of 9°C/km constrained by the AFT and AHe data from the craton and a mean surface temperature of 20°C indicate removal of up to 9?±?2?km of overburden since the end of Paleozoic. The correlation of erosion of the craton and sedimentation and subsidence within the Congo basin in the Paleozoic may indicate regional flexural geodynamics of the lithosphere due to lithosphere buckling induced by far-field compressional tectonic processes and thereafter through deep mantle upwelling and epeirogeny tectonic processes.
DS201908-1800
2019
Persaud, P.Netto, A., Pulliam, J., Persaud, P.Synoptic view of lithospheric S-wave velocity structure in the southern United States: a comparison of 3D seismic tomographic models.GSA Today, Vol. 29, 7, pp. 4-10. United Statesgeophysics - seismic

Abstract: The southern U.S. continental margin records a history spanning ca. 1.2 Ga, including two Wilson cycles. However, due to a thick sediment cover, the paucity of significant local seismicity, and, until recently, sparse instrumentation, details of this passive margin’s tectonomagmatic evolution remain disputed. This paper compares recent S-wave tomography and crustal thickness models based on USArray data to help establish a framework for geodynamic interpretation. Large-scale patterns of crustal velocity anomalies, corresponding to major regional features such as the Ouachita orogenic front and the Precambrian margin, are generally consistent between the models. The spatial extent of smaller-scale tectonic features, such as the Sabine Uplift and Wiggins block, remains poorly resolved. An inverse relationship between crustal thickness and Bouguer gravity across the continental margin is observed. This model comparison highlights the need for additional P-wave tomography studies and targeted, higher density station deployments to better constrain tectonic features.
DS201809-2089
2018
Persaud, S.Smit, K.V., Myagkaya, E., Persaud, S., Wang, W.Black diamonds from Marange ( Zimbabwe): a result of natural irradiation and graphite inclusions.Gems & Gemology, Vol. 54, 2, pp. 132-148.Africa, Zimbabwedeposit - Marange

Abstract: This study investigates the color origin of 40 natural Fancy Dark brown-black round brilliant diamonds from the Marange alluvial deposits in eastern Zimbabwe. Visual observations show that the dark appearance of the Marange diamonds is due to a combination of graphite micro-inclusions (associated with methane), graphite needles, and dark brown radiation stains that occur along internal fractures. The GR1 (V0) defect, typically formed during natural and artificial irradiation, is observed in the optical spectra of 43% of the diamonds, al- though its intensity is too low to significantly impact the bodycolor. Natural irradiation in these diamonds is likely related to their billion-year residence in the Umkondo conglomerate, which is known to contain radioac- tive minerals such as zircon. Aside from radiation staining, irradiation-damaged diamond appears non-lumines- cent in DiamondView images and shows a weaker, broader diamond peak (at 1332 cm?1) in Raman spectroscopy. Brown coloration of the radiation stains is due to heating of the diamonds during later regional metamorphism, which also facilitated the formation of the H3 (NVN0) and NiN complexes.
DS202102-0229
2020
Persaud, S.Wang, W., Yazawa, E., Persaud, S., Myagkaya, E., D'Haenens-Johansson, U., Moses, T.M.Formation of the Matryoshka diamond from Siberia.Gems & Gemology , Vol. 56, 1, pp. 127-129.Russia, Siberiadiamond crystalography

Abstract: A freely moving diamond trapped inside another diamond was discovered in Siberia by Alrosa in 2019. The unusual diamond, nicknamed the “Matryoshka” after the traditional Russian nesting dolls, attracted widespread interest in how this feature formed.
DS202110-1633
2021
Persaud, S.Persaud, S., Galati, A., Johnson, P.Colorful inclusions in diamond.Gems & Gemology, Vol. 57, 2, pp. 158-159. gia.edu/gems-gemologyUnited States, Californiadiamond inclusions
DS2000-0758
2000
Pershuk, L.L.Pershuk, L.L.Fluids in the lower crust and upper mantle of the EarthMoscow University Geology Bulletin, Vol.55,4,pp.14-27., Vol.55,4,pp.14-27.MantleGeochemistry
DS2000-0759
2000
Pershuk, L.L.Pershuk, L.L.Fluids in the lower crust and upper mantle of the EarthMoscow University Geology Bulletin, Vol.55,4,pp.14-27., Vol.55,4,pp.14-27.MantleGeochemistry
DS201503-0160
2015
Persiano, A.I.C.Menezes Filho, L.A.D., Atencio, D., Andrade, M.B., Downs, R.T., Chaves, M.L.S.C., Romano, A.W., Scholz, R., Persiano, A.I.C.Pauloabibite, trigonal NaNbO3, isostructural with ilmenite, from the Jacupiranga carbonatite, Cajati, Sao Paulo, Brazil.American Mineralogist, Vol. 100, pp. 442-446.South America, BrazilCarbonatite
DS201412-0679
2014
Persikov, E.Persikov, E., Bukhtiyarov, P., Skol, A., Palyanov, Y.Viscosity of kimberlite and basaltic magmas to 10 Gpa and 2000K.V.S. Sobolev Institute of Geology and Mineralogy Siberian Branch Russian Academy of Sciences International Symposium Advances in high pressure research: breaking scales and horizons ( Courtesy of N. Poikilenko), Held Sept. 22-26, 2p. AbstractMantleMagmatism
DS201012-0576
2009
Persikov, E.S.Persikov, E.S., Bukhityarov, P.G.Interrelated structural chemical model to predict and calculate viscosity of magmatic melts and water diffusion in a wide range of compositions and T-P parametersRussian Geology and Geophysics, Vol. 50, 12, pp. 1079-1090.MantleMagmatism
DS201507-0331
2015
Persikov, E.S.Persikov, E.S., Bukhtiyarov, P.G., Sokol, A.G.Change in the viscosity of kimberlite and basaltic magmas during their origin and evolution ( prediction).Russian Geology and Geophysics, Vol. 56, pp. 885-892.Canada, Northwest Territories, RussiaDeposit - Jericho, Udachnaya
DS201712-2717
2017
Persikov, E.S.Persikov, E.S., Bukhtiyarov, P.G., Sokol, A.G.Viscosity of hydrous kimberlite and basaltic melts at high pressures.Russian Geology and Geophysics, Vol. 58, pp. 1093-1100.Mantlekimberlite

Abstract: New experimental data on the temperature and pressure dependences of the viscosity of synthetic hydrous kimberlite melts (82 wt.% silicate + 18 wt.% carbonate; degree of depolymerization: 100NBO/T = 313 for anhydrous melts and 100NBO/T = 247 for melts with 3 wt.% H2O) were obtained at a water pressure of 100 MPa and at lithostatic pressures of 5.5 and 7.5 GPa in the temperature range 1300-1950 °C. The temperature dependence of the viscosity of these melts follows the exponential Arrhenius-Frenkel-Eyring equation in the investigated range of temperatures and pressures. The activation energies of viscous flow for hydrous kimberlite melts were first shown to increase linearly with increasing pressure. Under isothermal conditions (T = 1800 °C), the viscosity of hydrous kimberlite melts increases exponentially by about an order of magnitude as the pressure increases from 100 MPa to 7.5 GPa. The new experimental data on the viscosity of hydrous kimberlite melts (error ± 30 rel.%) are compared with forecast viscosity data for anhydrous kimberlite and basaltic melts (100NBO/T = 51.5) and for hydrous basaltic melts (100NBO/T = 80). It is shown that at comparable temperatures, the viscosity of hydrous kimberlite melts at a moderate pressure (100 MPa) is about an order of magnitude lower than the viscosity of hydrous basaltic melts, whereas at a high pressure (7.5 GPa) it is more than twice higher. It is first established that water dissolution in kimberlite melts does not affect seriously their viscosity (within the measurement error) at both moderate (100 MPa) and high (7.5 GPa) pressures, whereas the viscosity of basaltic melts considerably decreases with water dissolution at moderate pressures (100 MPa) and remains unchanged at high pressures (P > 3.5 GPa).
DS201803-0470
2017
Persikov, E.S.Persikov, E.S., Bukhtiyarov, P.G., Sokol, A.G.Viscosity of hydrous kimberlite and basaltic melts at high pressures.Russian Geology and Geophysics, Vol. 58, pp. 1093-1100.Mantlemelting

Abstract: New experimental data on the temperature and pressure dependences of the viscosity of synthetic hydrous kimberlite melts (82 wt.% silicate + 18 wt.% carbonate; degree of depolymerization: 100NBO/T = 313 for anhydrous melts and 100NBO/T = 247 for melts with 3 wt.% H2O) were obtained at a water pressure of 100 MPa and at lithostatic pressures of 5.5 and 7.5 GPa in the temperature range 1300-1950 °C. The temperature dependence of the viscosity of these melts follows the exponential Arrhenius-Frenkel-Eyring equation in the investigated range of temperatures and pressures. The activation energies of viscous flow for hydrous kimberlite melts were first shown to increase linearly with increasing pressure. Under isothermal conditions (T = 1800 °C), the viscosity of hydrous kimberlite melts increases exponentially by about an order of magnitude as the pressure increases from 100 MPa to 7.5 GPa. The new experimental data on the viscosity of hydrous kimberlite melts (error ± 30 rel.%) are compared with forecast viscosity data for anhydrous kimberlite and basaltic melts (100NBO/T = 51.5) and for hydrous basaltic melts (100NBO/T = 80). It is shown that at comparable temperatures, the viscosity of hydrous kimberlite melts at a moderate pressure (100 MPa) is about an order of magnitude lower than the viscosity of hydrous basaltic melts, whereas at a high pressure (7.5 GPa) it is more than twice higher. It is first established that water dissolution in kimberlite melts does not affect seriously their viscosity (within the measurement error) at both moderate (100 MPa) and high (7.5 GPa) pressures, whereas the viscosity of basaltic melts considerably decreases with water dissolution at moderate pressures (100 MPa) and remains unchanged at high pressures (P > 3.5 GPa).
DS201810-2365
2018
Persikov, E.S.Persikov, E.S., Bukhityarov, P.G., Sokol, A.G.Viscosity of haplokimberlitic and basaltic melts at high pressures: experimental and theoretical studies.Chemical Geology, Vol. 497, pp. 54-63.MantleUHP

Abstract: Only limited data are available at present on the viscosity of kimberlite magmas. We investigate viscosity of synthetic carbonate-bearing (silicate82?+?carbonate18, wt%, 100NBO/T?=?313) anhydrous haplokimberlite melts theoretically and in experiments. We use new experimental data on viscosity of anhydrous haplokimberlite melts and a physical-chemical model (Persikov and Bukhtiyarov 2009; Persikov et al. 2015) to compare basic viscosity features in kimberlitic and basaltic melts (100NBO/T?=?56). Viscosity of melts is determined by the falling sphere quenching method in a large range of temperatures from 1300 to 1950?°C and pressures up to 7.5?GPa. We use two types of high-pressure apparatuses: a high gas pressure apparatus and a high pressure split-sphere multi-anvil apparatus to study the viscosity of melts at moderate (100?MPa CO2 pressure) and high (5.5?GPa and 7.5?GPa) pressures, respectively. The measured viscosity ranges for anhydrous haplokimberlite melts are from 1.5 (±0.45) to 0.11(±0.03) Pa s. The temperature dependence of the viscosity of haplokimberlite and basaltic melts is consistent with the theoretical Arrhenian equation. At a constant temperature, viscosity of anhydrous haplokimberlite melts increases exponentially about ten-fold as pressure increases from 100?MPa to 7.5?GPa. The activation energy of viscous flow increases linearly with pressure increase from 100?MPa to 7.5?GPa for anhydrous haplokimberlite melts but decreases in the case of basaltic melts, with the minimum at ~5.5?GPa. At a moderate pressure (100?MPa), haplokimberlite melts are about twenty times less viscous than basaltic melts, but are about four times more viscous at a high pressure (7.5?GPa), the temperature being 1800?°C in both cases. The experimentally observed behavior of the viscosity of anhydrous haplokimberlite melts is consistent with predictions of the physical-chemical model within the range of uncertainties in both experimental and calculated data (±30% rel.). Thus, the physical-chemical model is used to discuss possible effects of volume percentages of crystals and bubbles on viscosity of kimberlitic and basaltic magmas at different pressures and temperatures during their origin, evolution, and ascent.
DS202205-0719
2022
Persikov, E.S.Sokol, A.G., Kruk, A.N., Persikov, E.S.Dissolution of peridotite in a volatile-rich carbonate melt as a mechanism of the formation of kimberlite-like melts ( experimental constraints).Doklady Earth Science, Vol. 503, 2, pp. 157-163.Globalkimberlite magmatism

Abstract: In the experiments at 3.0-6.3 GPa and 1200-1350°C, it is found that under P-T parameters close to the conditions in ascending kimberlite magma, the carbonate melt enriched in potassium and volatiles is able to dissolve effectively the entire amount of xenogenic peridotite material that can potentially transport. As a result of this process, the melt is enriched in SiO2 (up to 30 wt %) and is transformed from carbonate to a kimberlite-like one. In the range of parameters studied, due to the high solubility of CO2 in the melt and the appearance of magnesite, an equilibrium fluid phase is not formed in the system. The interaction realized in the experiments may be the most important factor at the initial stage of magma evolution. The calculations performed in this work show that even after the dissolution of 30-50 wt % of lherzolite, the volatile-rich carbonate-silicate melt has a high degree of depolymerization (the ratio of the number of nonbridging oxygen atoms to the number of tetrahedrally coordinated ions (100NBO/T from 250 to 390) remains low-viscous (0.3-32.6 Pa s) and able to ascend to the surface rapidly. The obtained data indicate that immiscibility occurs between the potassium-rich carbonate-silicate and highly silicate melts only at 5.5 GPa and 1350°C and is likely to have a minor impact on the evolution of magma.
DS2003-1069
2003
Personen, L.J.Personen, L.J., Elming, Mertansen, Pisarvesky, D' Agrilla Filho, Meert, SchmidtPaleomagnetic configuration of continents during the ProterozoicTectonophysics, Vol. 375, 1-4, pp. 289-324.MantleMagnetics
DS200412-1532
2003
Personen, L.J.Personen, L.J., Elming, Mertansen, Pisarvesky, D' Agrilla Filho, Meert, Schmidt, Abrahamsen, BylundPaleomagnetic configuration of continents during the Proterozoic.Tectonophysics, Vol. 375, 1-4, pp. 289-324.MantleMagnetics
DS201905-1077
2018
Personen, L.J.Soderlund, U., Bleeker, W., Demirer, K., Srivastava, R.K., Hamilton, M., Nilsson, M., Personen, L.J., Samal, A.K., Jayananda, M., Ernst, R.E., Srinivas, M.Emplacement ages of Paleoproterozoic mafic dyke swarms in eastern Dharwar craton, India: implications for paleoreconstructions and support for a ~30 degree change in dyke trends from south to north.Precambrian Research, doi.org/10.1016/ j.precamres.2018.12.017Indiacraton

Abstract: Large igneous provinces (LIPs) and especially their dyke swarms are pivotal to reconstruction of ancient supercontinents. The Dharwar craton of southern Peninsular India represents a substantial portion of Archean crust and has been considered to be a principal constituent of Superia, Sclavia, Nuna/Columbia and Rodinia supercontinents. The craton is intruded by numerous regional-scale mafic dyke swarms of which only a few have robustly constrained emplacement ages. Through this study, the LIP record of the Dharwar craton has been improved by U-Pb geochronology of 18 dykes, which together comprise seven generations of Paleoproterozoic dyke swarms with emplacement ages within the 2.37-1.79 Ga age interval. From oldest to youngest, the new ages (integrated with U-Pb ages previously reported for the Hampi swarm) define the following eight swarms with their currently recommended names: NE-SW to ESE-WNW trending ca. 2.37 Ga Bangalore-Karimnagar swarm. N-S to NNE-SSW trending ca. 2.25 Ga Ippaguda-Dhiburahalli swarm. N-S to NNW-SSE trending ca. 2.22 Ga Kandlamadugu swarm. NW-SE to WNW-ESE trending ca. 2.21 Ga Anantapur-Kunigal swarm. NW-SE to WNW-ESE trending ca. 2.18 Ga Mahbubnagar-Dandeli swarm. N-S, NW-SE, and ENE-WSW trending ca. 2.08 Ga Devarabanda swarm. E-W trending 1.88-1.89 Ga Hampi swarm. NW-SE ca. 1.79 Ga Pebbair swarm. Comparison of the arcuate trends of some swarms along with an apparent oroclinal bend of ancient geological features, such as regional Dharwar greenstone belts and the late Archean (ca. 2.5 Ga) Closepet Granite batholith, have led to the hypothesis that the northern Dharwar block has rotated relative to the southern block. By restoring a 30° counter clockwise rotation of the northern Dharwar block relative to the southern block, we show that pre-2.08 Ga arcuate and fanning dyke swarms consistently become approximately linear. Two possible tectonic models for this apparent bending, and concomitant dyke rotations, are discussed. Regardless of which deformation mechanisms applies, these findings reinforce previous suggestions that the radial patterns of the giant ca. 2.37 Ga Bangalore-Karimnagar dyke swarm, and probably also the ca. 2.21 Ga Anantapur-Kunigal swarm, may not be primary features.
DS1983-0513
1983
Persson, A.Persson, A.Electron States Associated with Partial Dislocations in Diamond.Journal of PHYSICS (PARIS), Vol. 44, No. C-4, PP. C4-453-460.GlobalCrystallography
DS1975-0119
1975
Persson, L.Kresten, P., Persson, L.Discrete Diopside in Alnoite from Alno IslandContributions to Mineralogy and Petrology, Vol. 39, PP. 103-116.Sweden, ScandinaviaAlnoite, Pyroxene, Mineralogy
DS2002-1697
2002
Persson, P.O.Weihed, P., Billstrom, K., Persson, P.O., Weihed, J.B.Relationship between 1.90 - 1.85 Ga accretionary processes and 1.82-1.80 Ga oblique subduction at the Karelian craton margin, Fennoscandian Shield.Geological Society of Sweden, GFF, Vol. 124, No. 3, pp.163-180.SwedenTectonics - craton
DS1960-0645
1966
Pert, I.G.Cooper, D.G., Pert, I.G., Wells, T., Willis, P.M.R.Report on the Visit to Kentanna Minerals, KentuckySelection Trust Exploration Ltd., INTERNAL UNPUBL. Report APRIL 20TH. 15P.United States, Appalachia, KentuckyGeology
DS2001-1013
2001
PertelSarayev, A.L., Pertel, Garat, Manakov, AlexandrovPossibilities of magnetotellurics for kimberlite exploration in the Russian PlatformNorth Atlantic Minerals Symposium held May 27-30, pp. 149. abstract.RussiaGeophysics - magnetotellurics
DS200512-0935
2002
Pertel, M.I.Saraev, A.K., Pertel, M.I., Nikiforov, A.B., Garat, M.N., Manakov, A.B., Ingerov, O.I.Magnetotelluric exploration for kimberlite pipes in Yakutian Province, Sakha Republic, Russia.Phoenix Geophysics Preprint, English, Jan. 7p. text 17 figuresRussia, Siberia, YakutiaGeophysics - magnetotellurics, Almakinskaya, Mirensky
DS2002-1248
2002
Pertermann, M.Pertermann, M., Hirschmann, M.M.Trace element partitioning between vacancy rich eclogitic clinopyroxene and silicate melt.American Mineralogist, Vol.87, pp. 1365-76.GlobalEclogites
DS2002-1249
2002
Pertermann, M.Pertermann, M., Hirschmann, M.M.Trace element partioning between vacancy rich eclogitic clinopyroxene and silicate meltAmerican Mineralogist, Vol. 87, pp. 1365-76.MantleEclogites, Petrology - experimental
DS200512-0555
2004
Pertermann, M.Kogiso, T., Hirschmann, M.M., Pertermann, M.High pressure partial melting of mafic lithologies in the mantle.Journal of Petrology, Vol. 45, 12, Dec. pp. 2407-2422.MantleUHP
DS1995-1162
1995
Pertsev, N.N.Marakushev, A.A., Pertsev, N.N., Zotov, I.A., Paneyakh, N.Some petrological aspects of diamond genesisGeology of Ore Deposits, Vol. 37, No. 2, March-April pp. 88-102.RussiaDiamond genesis, lamproite, Petrology
DS1995-1163
1995
Pertsev, N.N.Marakushev, A.A., Pertsev, N.N., Zotov, I.A., Paneyakh, N.A.Petrology of Diamondiferous magmatismProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 350-351.MantleMagmatism, Metamorphic complexes
DS1996-0884
1996
Pertsev, N.N.Marakushev, A.A., Pertsev, N.N., Zotov, I.A., PaneyakhSome petrological aspects of genesis of diamondInternational Geological Congress 30th Session Beijing, Abstracts, Vol. 2, p. 400.RussiaPetrology, Diamond genesis
DS1998-0939
1998
PertsovMarakushev, A.A., Paneyakh, N.A., Rusinov, PertsovPetrological model of giant ore depositsGeology of Ore Deposits, Vol. 40, No. 3, May-June pp. 211-227RussiaMetallogeny, Petrology
DS1992-1187
1992
Perttunen, M.Perttunen, M.Glaciofluvial transport of clasts and heavy minerals from the Sokli carbonatite complex, Finnish Lapland.Geological Survey of Finland, Bulletin. 366, 21p.FinlandGeomorphology, Carbonatite
DS2002-1273
2002
Perugini, D.Poli, G., Perugini, D.Strange attractors in magmas: evidence from lava flowsLithos, Vol. 65, 3-4, Dec. pp. 287-97.GlobalMagmatism
DS200512-0850
2005
Perugini, D.Petrilli, M., Poli, G., Perugini, D., Peccerillo, A.PetroGraph: a new software to visualize, model, and present geochemical dat a in igneous petrology.Geochemistry, Geophysics, Geosystems: G3, Vol. 6, doi. 10.1029/2005 GC000932TechnologyComputer - program, PetroGraph, major, trace elements
DS201809-2029
2018
Perugini, D.Gonzalez-Garcia, D., Petrelli, M., Behrens, H., Vetere, F., Fischer, L.A., Morgavi, D., Perugini, D.Diffusive exchange of trace elements between alkaline melts: implications for element fractionation and timescale estimations during magma mixing.Geochimica et Cosmochimica Acta, Vol. 233, pp. 95-114.Europe, Italyshoshonites

Abstract: The diffusive exchange of 30 trace elements (Cs, Rb, Ba, Sr, Co, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ta, V, Cr, Pb, Th, U, Zr, Hf, Sn and Nb) during the interaction of natural mafic and silicic alkaline melts was experimentally studied at conditions relevant to shallow magmatic systems. In detail, a set of 12 diffusion couple experiments have been performed between natural shoshonitic and rhyolitic melts from the Vulcano Island (Aeolian archipelago, Italy) at a temperature of 1200?°C, pressures from 50 to 500?MPa, and water contents ranging from nominally dry to ca. 2 wt.%. Concentration-distance profiles, measured by Laser Ablation ICP-MS, highlight different behaviours, and trace elements were divided into two groups: (1) elements with normal diffusion profiles (13 elements, mainly low field strength and transition elements), and (2) elements showing uphill diffusion (17 elements including Y, Zr, Nb, Pb and rare earth elements, except Eu). For the elements showing normal diffusion profiles, chemical diffusion coefficients were estimated using a concentration-dependent evaluation method, and values are given at four intermediate compositions (SiO2 equal to 58, 62, 66 and 70 wt.%, respectively). A general coupling of diffusion coefficients to silica diffusivity is observed, and variations in systematics are observed between mafic and silicic compositions. Results show that water plays a decisive role on diffusive rates in the studied conditions, producing an enhancement between 0.4 and 0.7 log units per 1 wt.% of added H2O. Particularly notable is the behaviour of the trivalent-only REEs (La to Nd and Gd to Lu), with strong uphill diffusion minima, diminishing from light to heavy REEs. Modelling of REE profiles by a modified effective binary diffusion model indicates that activity gradients induced by the SiO2 concentration contrast are responsible for their development, inducing a transient partitioning of REEs towards the shoshonitic melt. These results indicate that diffusive fractionation of trace elements is possible during magma mixing events, especially in the more silicic melts, and that the presence of water in such events can lead to enhanced chemical diffusive mixing efficiency, affecting also the estimation of mixing to eruption timescales.
DS202102-0176
2021
Peruzo, L.Brenker, F.E., Nestola, F., Brenker, L., Peruzo, L., Harris, J.WOrigin, properties, and structure of breyite: the second most abundant mineral inclusion in super-deep diamonds.The American Mineralogist, Vol. 106, pp. 38-43. pdfMantleperovskites, mineral inclusions

Abstract: Earth's lower mantle most likely mainly consists of ferropericlase, bridgmanite, and a CaSiO3- phase in the perovskite structure. If separately trapped in diamonds, these phases can be transported to Earth's surface without reacting with the surrounding mantle. Although all inclusions will remain chemically pristine, only ferropericlase will stay in its original crystal structure, whereas in almost all cases bridgmanite and CaSiO3-perovskite will transform to their lower-pressure polymorphs. In the case of perovskite structured CaSiO3, the new structure that is formed is closely related to that of walstromite. This mineral is now approved by the IMA commission on new minerals and named breyite. The crystal structure is triclinic (space group: P1) with lattice parameters a0 = 6.6970(4) Å, b0 = 9.2986(7) Å, c0 = 6.6501(4) Å, ? = 83.458(6)°, ? = 76.226(6)°, ? = 69.581(7)°, and V = 376.72(4) Å. The major element composition found for the studied breyite is Ca3.01(2)Si2.98(2)O9. Breyite is the second most abundant mineral inclusion after ferropericlase in diamonds of super-deep origin. The occurrence of breyite has been widely presumed to be a strong indication of lower mantle (=670 km depth) or at least lower transition zone (=520 km depth) origin of both the host diamond and the inclusion suite. In this work, we demonstrate through different formation scenarios that the finding of breyite alone in a diamond is not a reliable indicator of the formation depth in the transition zone or in the lower mantle and that accompanying paragenetic phases such as ferropericlase together with MgSiO3 are needed.
DS201712-2711
2016
Peruzzo, L.Nestola, F., Burnham, A.D., Peruzzo, L., Tauro, L., Alvaro, M., Walter, M.J., Gunter, M., Anzolini, C., Kohn, S.C.Tetragonal almandine-pyrope phase, TAPP: finally a name for it, the new name jeffbenite.Mineralogical Magazine, Vol. 80, pp. 1219-1232.Technologypyrope

Abstract: Jeffbenite, ideally Mg3Al2Si3O8, previously known as tetragonal-almandine-pyrope-phase (‘TAPP’), has been characterized as a new mineral from an inclusion in an alluvial diamond from São Luiz river, Juina district of Mato Grosso, Brazil. Its density is 3.576 g/cm3 and its microhardness is ?7. Jeffbenite is uniaxial (-) with refractive indexes ??=?1.733(5) and ??=?1.721(5). The crystals are in general transparent emerald green. Its approximate chemical formula is (Mg2.62Fe2+0.27)(Al1.86Cr0.16)(Si2.82Al0.18)O12 with very minor amounts of Mn, Na and Ca. Laser ablation ICP-MS showed that jeffbenite has a very low concentration of trace elements. Jeffbenite is tetragonal with space group I4¯2d, cell edges being a?=?6.5231(1) and c?=?18.1756(3) Å. The main diffraction lines of the powder diagram are [d (in Å), intensity, hkl]: 2.647, 100, 2 0 4; 1.625, 44, 3 2 5; 2.881, 24, 2 1 1; 2.220, 19, 2 0 6; 1.390, 13, 4 2 4; 3.069, 11, 2 0 2; 2.056, 11, 2 2 4; 1.372, 11, 2 0 12. The structural formula of jeffbenite can be written as (M1)(M2)2(M3)2(T1)(T2)2O12 with M1 dominated by Mg, M2 dominated by Al, M3 dominated again by Mg and both T1 and T2 almost fully occupied by Si. The two tetrahedra do not share any oxygen with each other (i.e. jeffbenite is classified as an orthosilicate). Jeffbenite was approved as a new mineral by the IMA Commission on New Minerals and Mineral Names with the code IMA 2014-097. Its name is after Jeffrey W. Harris and Ben Harte, two world-leading scientists in diamond research. The petrological importance of jeffbenite is related to its very deep origin, which may allow its use as a pressure marker for detecting super-deep diamonds. Previous experimental work carried out on a Ti-rich jeffbenite establishes that it can be formed at 13 GPa and 1700 K as maximum P-T conditions.
DS201804-0723
2018
Peruzzo, L.Nestola, F., Korolev, N., Kopylova, M., Rotiroti, N., Pearson, D.G., Pamato, M.G., Alvaro, M., Peruzzo, L., Gurney, J.J., Moore, A.E., Davidson, J.CaSiO3 perovskite in diamond indicates the recycling of oceanic crust into the lower mantle.Nature, Vol. 555, March 8, pp. 237-241.Mantledeposit - Cullinan

Abstract: Laboratory experiments and seismology data have created a clear theoretical picture of the most abundant minerals that comprise the deeper parts of the Earth’s mantle. Discoveries of some of these minerals in ‘super-deep’ diamonds—formed between two hundred and about one thousand kilometres into the lower mantle—have confirmed part of this picture1,2,3,4,5. A notable exception is the high-pressure perovskite-structured polymorph of calcium silicate (CaSiO3). This mineral—expected to be the fourth most abundant in the Earth—has not previously been found in nature. Being the dominant host for calcium and, owing to its accommodating crystal structure, the major sink for heat-producing elements (potassium, uranium and thorium) in the transition zone and lower mantle, it is critical to establish its presence. Here we report the discovery of the perovskite-structured polymorph of CaSiO3 in a diamond from South African Cullinan kimberlite. The mineral is intergrown with about six per cent calcium titanate (CaTiO3). The titanium-rich composition of this inclusion indicates a bulk composition consistent with derivation from basaltic oceanic crust subducted to pressures equivalent to those present at the depths of the uppermost lower mantle. The relatively ‘heavy’ carbon isotopic composition of the surrounding diamond, together with the pristine high-pressure CaSiO3 structure, provides evidence for the recycling of oceanic crust and surficial carbon to lower-mantle depths.https://www.nature.com/articles/nature25972
DS201905-1020
2019
Peruzzo, L.Cesare, B., Nestola, F., Mugnaioli, E., Della Ventura, G., Peruzzo, L., Bartoli, O., Viti, C., Johnson, T., Erickson, T.I was not born cubic, said low temperature metamorphic garnet. Geophysical Research Abstracts EGRU2019-3091, Vol. 21, 3091, 1p.Europe, Alpsgarnet

Abstract: Garnet is the paradigmatic cubic mineral of metamorphic and igneous rocks, and is generally regarded as optically isotropic. Nonetheless, evident birefringence is observed, particularly in the rare CaFe 3+ hydrogarnets, which is attributed to the coexistence of two or more cubic phases. A weak birefringence, with rare examples of optical sector zoning, has also been documented in much more common Fe 2+-Mg-Mn garnets, but an adequate explanation for its cause is, so far, lacking. Here we show that optically anisotropic garnets are much more widespread than previously thought, both in blueschists and blueschist-facies rocks, as well as in lower greenschist-facies phyllites, but they are frequently overlooked when working with conventional, 30-µm-thick thin sections. Utilizing a multi-technique approach including optical microstructural analysis, BSEM, EMPA, EBSD, FTIR, TEM, EDT and single-crystal XRD, we demonstrate here that the birefringence in these garnets is related to their tetragonal symmetry, that it is not due to strain, and that crystals are twinned according to a merohedral law. We also show that the birefringent garnets from blueschists and phyllites are anhydrous, lacking any hydrogarnet component, and have compositions dominated by almandine (58-79%) and grossular (19-30%) with variable spessartine (0-21%) and very low pyrope (1-7%). Considering the widespread occurrence of optically anisotropic OH-free garnets in blueschists and phyllites, their common low-grade metamorphic origin, and the occurrence of optically isotropic garnets with similar Ca-rich almandine composition in higher-grade rocks, we conclude that garnet does not grow with cubic symmetry in low-temperature rocks (< 400 • C). The tetragonal structure appears to be typical of Fe-Ca-rich compositions, with very low Mg contents. Cubic but optically sector-zoned garnet in a lower amphibolite-facies metapelite from the eastern Alps suggests that preservation of tetragonal garnet is favored in rocks which did not progress to T> ?500 • C, where transition to the cubic form, accompanied by change of stable chemical composition, would take place. Our data show that the crystal-chemistry of garnet, its thermodynamics and, in turn, its use in unravelling petrogenetic processes in cold metamorphic environments need to be reassessed.
DS201907-1524
2019
Peruzzo, L.Anzolini, C., Wang, F., Harris, G.A., Locock, A.J., Zhang, D., Nestola, F., Peruzzo, L., Jacobsen, S.D., Pearson, D.G.Nixonite, Na2Ti6O13, a new mineral from a metasomatized mantle garnet pyroxenite from the western Rae Craton, Darby kimberlite field, Canada.American Mineralogist, in press available 26p.Canada, Nunavutdeposit - Darby

Abstract: Nixonite (IMA 2018-133), ideally Na2Ti6O13, is a new mineral found within a heavily-metasomatized pyroxenite xenolith from the Darby kimberlite field, beneath the west central Rae Craton, Canada. It occurs as microcrystalline aggregates, 15 to 40 ?m in length. Nixonite is isostructural with jeppeite, K2Ti6O13, with a structure consisting of edge- and corner-shared titanium-centered octahedra that enclose alkali-metal ions. The Mohs hardness is estimated to be between 5 and 6 by comparison to jeppeite and the calculated density is 3.51(1) g/cm3. Electron microprobe wavelength-dispersive spectroscopic analysis (average of 6 points) yielded: Na2O 6.87, K2O 5.67 CaO 0.57, TiO2 84.99, V2O3 0.31, Cr2O3 0.04, MnO 0.01, Fe2O3 0.26, SrO 0.07, total 98.79 wt%. The empirical formula, based on 13 O atoms, is: (Na1.24K0.67Ca0.06)?1.97(Ti5.96V0.023Fe0.018)?6.00O13 with minor amounts of Cr and Mn. Nixonite is monoclinic, space group C2/m, with unit-cell parameters a = 15.3632(26) Å, b = 3.7782(7) Å, c = 9.1266(15) Å, ? = 99.35(15)º and V = 522.72(1) Å3, Z = 2. Based on the average of seven integrated multi-grain diffraction images, the strongest diffraction lines are [dobs in Å (I in %) (h k l)]: 3.02 (100) (3 1 0) , 3.66 (75) (1 1 0), 7.57 (73) (2 0 0), 6.31 (68) (2 0 -1), 2.96 (63) (3 1 -1), 2.96 (63) (2 0 -3) and 2.71 (62) (4 0 2). The five main Raman peaks of nixonite, in order of decreasing intensity, are at: 863, 280, 664, 135 and 113 cm-1. Nixonite is named after Peter H. Nixon, a renowned scientist in the field of kimberlites and mantle xenoliths. Nixonite occurs within a pyroxenite xenolith in a kimberlite, in association with rutile, priderite, perovskite, freudenbergite and ilmenite. This complex Na-K-Ti rich metasomatic mineral assemblage may have been produced by a fractionated Na-rich kimberlitic melt that infiltrated a mantle-derived garnet pyroxenite and reacted with rutile during kimberlite crystallization.
DS201911-2514
2019
Peruzzo, L.Cesare, B., Nestola, F., Johnson, T., Mugnaioli, E., Della Ventura, G., Peruzzo, L., Bartoli, O., Viti, C., Erickson, T.Garnet, the archetypal cubic mineral, grows tetragonal.Nature Research, doi.org/10.1038/s41598-019-51214-9Mantlegarnet

Abstract: Garnet is the archetypal cubic mineral, occurring in a wide variety of rock types in Earth’s crust and upper mantle. Owing to its prevalence, durability and compositional diversity, garnet is used to investigate a broad range of geological processes. Although birefringence is a characteristic feature of rare Ca-Fe3+ garnet and Ca-rich hydrous garnet, the optical anisotropy that has occasionally been documented in common (that is, anhydrous Ca-Fe2+-Mg-Mn) garnet is generally attributed to internal strain of the cubic structure. Here we show that common garnet with a non-cubic (tetragonal) crystal structure is much more widespread than previously thought, occurring in low-temperature, high-pressure metamorphosed basalts (blueschists) from subduction zones and in low-grade metamorphosed mudstones (phyllites and schists) from orogenic belts. Indeed, a non-cubic symmetry appears to be typical of common garnet that forms at low temperatures (<450?°C), where it has a characteristic Fe-Ca-rich composition with very low Mg contents. We propose that, in most cases, garnet does not initially grow cubic. Our discovery indicates that the crystal chemistry and thermodynamic properties of garnet at low-temperature need to be re-assessed, with potential consequences for the application of garnet as an investigative tool in a broad range of geological environments.
DS202009-1613
2020
Peruzzo, L.Brenker, F.E., Nestola, F., Brenker, L., Peruzzo, L., Harris, J.W.Origin, properties and structure of breyite: the second most abundant mineral inclusion in super-deep diamonds. The American Mineralogist, in press available, 21p. PdfMantlebreyite
DS1999-0079
1999
PervovBogatikov, O.A., Kononova, V.A., Pervov, ParsadanyanUltramafic Diamondiferous rocks, Russian platform and geodynamicsStanley, SGA Fifth Biennial Symposium, pp. 1301-4.RussiaMelilitite, lamproite, lamprophyre, picrite
DS2000-0515
2000
PervovKononova, V.A., Pervov, Bogatikov, Parsadanyan et al.Potassic mafic rocks with megacrysts from northwestern Ladoga Lake area: diversity of mantle sources potassicGeochemistry International, Vol. 38, No.S1, pp. S39-58.Russia, Karelia, FennoscandiaTectonics, geochronology, alkaline, Shonkinite, minette
DS2001-0117
2001
PervovBogatikov, O.A., Kononova, V.A., Pervov, ZhuravlevSources, geodynamic setting of formation and diamond bearing potential of kimberlites from northern marginPetrology, Vol. 9, No. 3, pp. 191-203.RussiaPlate - Sr neodymium isotopic and ICP MS, Geochronology, geochemistry
DS2002-0873
2002
PervovKononova, V.A., Kurat, Embey-Isztin, Pervov, KoeberlGeochemistry of metasomatised spinel peridotite xenoliths from the Darigana Plateau, southeast MongoliaMineralogy and Petrology, Vol.75,1-2,pp. 1-21.MongoliaXenoliths
DS201112-0784
2011
Pervov, S.Pervov, S., Somov, V., Korshunov, A.V., Dulapchii, E.V.The Catoca kimberlite pipe, Republic of Angola: a paleovolcanological model.Geology of Ore Deposits, Vol. 53, no. 4, pp. 295-308.Africa, AngolaDeposit - Catoca
DS201212-0590
2012
Pervov, S.Robles-Cruz, S.E., Escayola, M., Jackson, S., Gali, S., Pervov, S., Watanga, M., Goncalves, A., Melgarejo, J.C.U-Pb SHRIMP geochronology of zircon from the Catoca kimberlite, Angola: implications for diamond exploration.Chemical Geology, Vol. 310-311, pp. 137-147.Africa, AngolaDeposit - Catoca
DS1998-0780
1998
Pervov, Sharkov et al.Kondrashov, I.A., Pervov, Sharkov et al.Layering in the southern Sakun high pressureotassium alkaline massif, AldanShield.Petrology, Vol. 6, No. 3, June, pp. 237-251.Russia, SiberiaGeochronology, Alkaline rocks
DS201112-0873
2011
Pervov, V.Robles-Cruz, S.E., Melgarejo, J.C., Escayola, M., Watangua, M., Pervov,V.Comparative composition of xenocrysts of garnet, clinopyroxene, and ilmenite from Diamondiferous and barren kimberlites from northeastern Angola.Peralk-Carb 2011... workshop June 16-18, Tubingen, Germany, Abstract p.129-131.Africa, AngolaCatoca, Kambundu, Tchiuzo, Cuilo
DS201112-0874
2011
Pervov, V.Robles-Cruz, S.E., Melgarejo, J.C., Escayola, M., Watangua, M., Pervov,V.Comparative composition of xenocrysts of garnet, clinopyroxene, and ilmenite from Diamondiferous and barren kimberlites from northeastern Angola.Peralk-Carb 2011... workshop June 16-18, Tubingen, Germany, Abstract p.129-131.Africa, AngolaCatoca, Kambundu, Tchiuzo, Cuilo
DS201708-1734
2017
Pervov, V.Pervov, V.Catoca kimberlite pipe diatreme/crater transition and dynamics of the crater sedimentation.11th. International Kimberlite Conference, PosterAfrica, Angoladeposit - Catoca
DS201711-2506
2017
Pervov, V.Castillo-Oliver, M., Melgarejo, J.C., Gali, S., Pervov, V., Goncalves, A.O., Griffin, W.L., Pearson, N.J., O'Reilly, S.Y.Use and misuse of Mg- and Mn- rich ilmenite in diamond exploration: a petrographic and trace element approach. Congo-Kasai cratonLithos, Vol. 292-293, pp. 348-363.Africa, Angoladeposit - CAT115, Tchiuzo

Abstract: Magnesian ilmenite is a common kimberlite indicator mineral, although its use in diamond exploration is still controversial. Complex crystallisation and replacement processes have been invoked to explain the wide compositional and textural ranges of ilmenite found in kimberlites. This work aims to shed light on these processes, as well as their implications for diamond exploration. Petrographic studies were combined for the first time with both major- and trace-element analyses to characterise the ilmenite populations found in xenoliths and xenocrysts in two Angolan kimberlites (Congo-Kasai craton). A multi-stage model describes the evolution of ilmenite in these pipes involving: i) crystallisation of ferric and Mg-rich ilmenite either as metasomatic phases or as megacrysts, both in crustal and in metasomatised mantle domains; ii) kimberlite entrainment and xenolith disaggregation producing at least two populations of ilmenite nodules differing in composition; iii) interaction of both types with the kimberlitic magma during eruption, leading to widespread replacement by Mg-rich ilmenite along grain boundaries and fractures. This process produced similar major-element compositions in ilmenites regardless of their primary (i.e., pre-kimberlitic) origin, although the original enrichment in HFSE (Zr, Hf, Ta, Nb) observed in Fe3 +-rich xenocrysts is preserved. Finally (iv) formation of secondary Mn-ilmenite by interaction with a fluid of carbonatitic affinity or by infiltration of a late hydrothermal fluid, followed in some cases by subsolidus alteration in an oxidising environment. The complexities of ilmenite genesis may lead to misinterpretation of the diamond potential of a kimberlite during the exploration stage if textural and trace-element information is disregarded. Secondary Mg-enrichment of ilmenite xenocrysts is common and is unrelated to reducing conditions that could favour diamond formation/preservation in the mantle. Similarly, Mn-rich ilmenite should be disregarded as a diamond indicator mineral, unless textural studies can prove its primary origin.
DS1993-1800
1993
Pervov, V.A.Yeremeyv, N.V., Zhuravlev, .Z., Kononova, V.A., Pervov, V.A., Kramm, U.Source and age of the potassic rocks in the Ryabinov intrusion, centralAldan.Geochemistry International, Vol. 30, No. 6, pp. 105-112.Russia, AldanAlkaline rocks
DS1994-0176
1994
Pervov, V.A.Bogatikov, O.A., Kononova, V.A., Pervov, V.A., ZhguralevPetrogenesis of Mesozoic potassic magmatism of the central Aldan: a isotopic and geodynamic model.International Geology Review, Vol. 36, No. 7, July pp. 629-644.Russia, AldanAlkalic rocks, Geochronology
DS1995-0992
1995
Pervov, V.A.Kononova, V.A., Bogatikov, O.A., Pervov, V.A., YeremeyevCentral Asian potassic magmatic rocks: geochemistry and formationconditions.Geochemistry International, Vol. 32, No. 2, pp. 23-42.Russia, AsiaAlkaline rocks, Geochemistry
DS1995-1486
1995
Pervov, V.A.Pervov, V.A.Isotopic evidence for lower crustal contamination in highly potassic intrusive rocks of Sakun Massif.Terra Nova, Abstract Vol., p. 336.Russia, Aldan, Siberia, RussiaGeochronology, Sakun Massif
DS1998-1124
1998
Pervov, V.A.Parsadanyan, K.S., Pervov, V.A., Bogatikov, KononvaGeochemical features of high magnesium alkaline rocks and their correlation with geological evolution - structureMineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 1137-8.Russia, Baltic ShieldAlkaline rocks, Geochemistry
DS2000-0473
2000
Pervov, V.A.Karpukhina, E.V., Pervov, V.A., Zhuravlev, TikhovaIsotope and geochemical indicators of the intraplate origin of mafic ultramafic rocks western slope of UralsDoklady Academy of Sciences, Vol. 370, No. 1, Jan-Feb pp. 153-6.Russia, UralsGeochemistry, Alkaline rocks
DS2000-0516
2000
Pervov, V.A.Kononova, V.A., Pervov, V.A., Ilupin, I.P.Geochemical and mineralogical correlation of kimberlites from Timan and Zimnii Bereg.Doklady Academy of Sciences, Vol. 372, No. 4, May-June pp. 724-7.RussiaGeochemistry, Deposit - Timan, Zimnii
DS2000-0517
2000
Pervov, V.A.Kononova, V.A., Pervov, V.A., Parsdanyan, K.S.Strontium-neodymium isotope age and geochemistry of megacryst bearing lamprophyres of Ladoga region: evidence lithospheric..Doklady Academy of Sciences, Vol. 370, No. 1, Jan-Feb pp.157-9.RussiaGeochronology, Lamprophyres
DS2002-0811
2002
Pervov, V.A.Karpukhina, E.V., Pervov, V.A., Suslov, ZorinSpatiotemporal evolution of the mantle source for picrites of the UralsDoklady, Vol.383A,3,March-April,pp. 296-300.UralsPicrite - genesis
DS2002-0876
2002
Pervov, V.A.Kononova, V.A., Levsky, L.K., Pervov, V.A., Ovchinnikova, G.V., BogatikovPb Sr Nd isotopic systematics of mantle sources of potassic ultramafic and mafic rocksPetrology, Vol. 10, 5, pp. 433-47.RussiaAlkaline rocks, Geochronology
DS2002-0877
2002
Pervov, V.A.Kononova, V.A., Levsky, L.K., Pervov, V.A., Ovchinnikova, G.V., BogatikovPb Sr Nd isotopic systematics of mantle sources of potassic ultramafic and mafic rocks in the north and east European platform.Petrology, Vol. 10, 5, pp. 433-47.Russia, UralsGeochronology, Alkaline rocks
DS2002-0878
2002
Pervov, V.A.Kononova, V.A., Levsky, L.K., Pervov, V.A., Ovchinnikova, G.V., Bogatikov, A.Pb Sr Nd isotopic systematics of mantle sources of potassic ultramafic and mafic rocksPetrology, Vol. 10, 5, pp. 433-47.Russia, Europe, Kola PeninsulaGeochronology
DS2002-1250
2002
Pervov, V.A.Pervov, V.A., Kononova, V.A., Ilupin, I.P., Simakov, S.K.PT parameters of formation of rocks included as xenoliths in kimberlites of middle Timan.Doklady Earth Sciences, Vol. 386, 7, Sept-Oct.pp. 867-9.Russia, TimanGeochronology
DS200512-0847
2005
Pervov, V.A.Pervov, V.A., Bogomolov, E.S., Larchenko, V.A., Levskii, L.K., Minchenko, Sabukov, Sergeev, StepanovRb Sr age of kimberlites of the Pionerskaya pipe, Arkangelsk Diamondiferous province.Doklady Earth Sciences, Vol. 400, 1, pp. 67-71.Russia, Archangel, Kola PeninsulaGeochronology
DS200612-0727
2006
Pervov, V.A.Kononova, V.A., Nosova, A.A., Pervov, V.A., Kondrashov, I.A.Compositional variations in kimberlites of the East European platform as a manifestation of sublithospheric geodynamic processes.Doklady Earth Sciences, Vol. 409A, no. 6, July-August, pp. 952-957.Russia, Baltic ShieldGeodynamics
DS200612-1083
2006
Pervov, V.A.Pervov, V.A., Larchenko, V.A., Minchenko, G.V., Stepanov, V.P., Bogomolov, E.S., Levskii, SergeevTiming and duration of kimberlitic magmatism in the Zimnii Bereg Diamondiferous province: evidence from Rb Sr age dat a on kimberlitic sills along the Mela River.Doklady Earth Sciences, Vol. 407, 2, Feb-Mar. pp. 304-307.RussiaGeochronology - Zimnii Bereg
DS200712-0368
2006
Pervov, V.A.Golubeva, Yu.Yu., Pervov, V.A., Kononova, V.A.Petrogenesis of autoliths from kimberlitic breccias in the V. Grib pipe, Arkangelsk district.Doklady Earth Sciences, Vol. 411, no. 8, pp. 1257-1262.Russia, Kola Peninsula, ArchangelDeposit - Grib
DS201612-2311
2016
Pervov, V.A.Kargin, A.V., Sazonova, L.V., Nosova, A.A., Pervov, V.A., Minevrina, E.V., Khvostikov, V.A., Burmii, Z.P.Sheared peridotite xenolith from the V. Grib kimberlite pipe, Arkangelsk diamond province, Russia: texture, composition and origin.Geoscience Frontiers, in press availableRussia, Archangel, Kola PeninsulaDeposit - Grib
DS2002-0874
2002
Pervov ...Kononova, V.A., Kurat, G., Embey Isztin, A., Pervov ...Geochemistry of metasomatised spinel peridotite xenoliths from the Dariganga PlateauMineralogy and Petrology, Vol.75,1-2,pp.1-22., Vol.75,1-2,pp.1-22.Mongolia, southeastXenoliths
DS2002-0875
2002
Pervov ...Kononova, V.A., Kurat, G., Embey Isztin, A., Pervov ...Geochemistry of metasomatised spinel peridotite xenoliths from the Dariganga PlateauMineralogy and Petrology, Vol.75,1-2,pp.1-22., Vol.75,1-2,pp.1-22.Mongolia, southeastXenoliths
DS200812-0836
2008
Pesaresi, M.Pagot, E., Pesaresi, M., Buda, D., Ehrlich, D.Development of an object oriented classification model using very high resolution satellite imagery for monitoring diamond mining activity.International Journal of Remote Sensing, Vol. 29, 2, Jan. pp. 499-512.AfricaRemote sensing - mine
DS201412-0010
2014
Pesce, G.Andrault,D., Pesce, G., Ali Bouhifd, M., Bolfan-Casanova, N., Henot, J-M., Mezouar, M.Melting of basalt at the core-mantle boundary.Science, Vol. 344, no. 6186, pp. 892-895.MantleSubduction
DS201412-0834
2014
Pesce, G.Sinmyo, R., Pesce, G., Greenberg, E., McCammon, C., Dubrovinsky, L.Lower mantle electrical conductivity based on measurements of Al, Fe-bearing perovskite under lower mantle conditions.Earth and Planetary Science Letters, Vol. 393, pp. 165-172.MantleGeophysics
DS201711-2499
2017
Pesce, G.Andrault, D., Bolfan-Casanova, N., Bouhifd, M.A., Boujibar, A., Garbarino, G., Manthilake, G., Mezouar, M., Monteux, J., Parisiades, P., Pesce, G.Toward a coherent model for the melting behaviour of the deep Earth's mantle.Physics of the Earth and Planetary Interiors, Vol. 265, pp. 67-81.Mantlemelting

Abstract: Knowledge of melting properties is critical to predict the nature and the fate of melts produced in the deep mantle. Early in the Earth’s history, melting properties controlled the magma ocean crystallization, which potentially induced chemical segregation in distinct reservoirs. Today, partial melting most probably occurs in the lowermost mantle as well as at mid upper-mantle depths, which control important aspects of mantle dynamics, including some types of volcanism. Unfortunately, despite major experimental and theoretical efforts, major controversies remain about several aspects of mantle melting. For example, the liquidus of the mantle was reported (for peridotitic or chondritic-type composition) with a temperature difference of ?1000 K at high mantle depths. Also, the Fe partitioning coefficient (DFeBg/melt) between bridgmanite (Bg, the major lower mantle mineral) and a melt was reported between ?0.1 and ?0.5, for a mantle depth of ?2000 km. Until now, these uncertainties had prevented the construction of a coherent picture of the melting behavior of the deep mantle. In this article, we perform a critical review of previous works and develop a coherent, semi-quantitative, model. We first address the melting curve of Bg with the help of original experimental measurements, which yields a constraint on the volume change upon melting (?Vm). Secondly, we apply a basic thermodynamical approach to discuss the melting behavior of mineralogical assemblages made of fractions of Bg, CaSiO3-perovskite and (Mg,Fe)O-ferropericlase. Our analysis yields quantitative constraints on the SiO2-content in the pseudo-eutectic melt and the degree of partial melting (F) as a function of pressure, temperature and mantle composition; For examples, we find that F could be more than 40% at the solidus temperature, except if the presence of volatile elements induces incipient melting. We then discuss the melt buoyancy in a partial molten lower mantle as a function of pressure, F and DFeBg/melt. In the lower mantle, density inversions (i.e. sinking melts) appear to be restricted to low F values and highest mantle pressures. The coherent melting model has direct geophysical implications: (i) in the early Earth, the magma ocean crystallization could not occur for a core temperature higher than ?5400 K at the core-mantle boundary (CMB). This temperature corresponds to the melting of pure Bg at 135 GPa. For a mantle composition more realistic than pure Bg, the right CMB temperature for magma ocean crystallization could have been as low as ?4400 K. (ii) There are converging arguments for the formation of a relatively homogeneous mantle after magma ocean crystallization. In particular, we predict the bulk crystallization of a relatively large mantle fraction, when the temperature becomes lower than the pseudo-eutectic temperature. Some chemical segregation could still be possible as a result of some Bg segregation in the lowermost mantle during the first stage of the magma ocean crystallization, and due to a much later descent of very low F, Fe-enriched, melts toward the CMB. (iii) The descent of such melts could still take place today. There formation should to be related to incipient mantle melting due to the presence of volatile elements. Even though, these melts can only be denser than the mantle (at high mantle depths) if the controversial value of DFeBg/melt is indeed as low as suggested by some experimental studies. This type of melts could contribute to produce ultra-low seismic velocity anomalies in the lowermost mantle.
DS201803-0432
2018
Pesce, G.Andrault, D., Pesce, G., Manthilake, G., Monteux, J., Volfan-Casanova, N., Chantel, J. , Novella, D., Guignot, N., King, A., Itie, J-P., Hennet, L.An archean mushy mantle.Nature Geoscience, Vol. 11, 2, pp. 85-86.Mantlegeodynamics

Abstract: Experimental data reveal that Earth’s mantle melts more readily than previously thought, and may have remained mushy until two to three billion years ago.
DS200812-1027
2008
PeschlerSchulmann, K., Lexa, O., Stipska, P., Racek, M., Tajcmanova, L., Konpasek, Edel, Peschler, LehmannVertical extension and horizontal channel flow of orogenic lower crust: key exhumation mechanisms in large hot orogens?Journal of Metamorphic Geology, In press availableEurope, MantleGeophysics - bouguer
DS1992-0847
1992
Peshko, M.Kerswill, J.A., Peshko, M.Regional mapping in the Winter Lake-Lac de Gras area: implications for theorigin, evolution and economic potential of the central Slave ProvinceNorthwest Territories Geoscience Forum held November 25, 26th. 1992, AbstractNorthwest TerritoriesGeneral, Not specific to diamonds
DS1993-1596
1993
Peshko, M.Thompson, P.H., Ross, D., Davidson, A., Froese, E., Kerswill, J.A., Peshko, M.Preliminary geology of the Winter Lake-Lac de Gras area, Northwestterritories, east half 86A.Geological Survey of Canada Open File, No. 2740, 1: 250, 000 1 map $ 15.00Northwest TerritoriesMap, Geology
DS1993-1597
1993
Peshko, M.Thompson, P.H., Ross, D., Froese, E., Kerswill, J., Peshko, M.Regional geology in the Winter Lake-Lac de Gras area, central SlaveProvince, District of Mackenzie, N.W.T.Geological Survey Canada Paper, No. 93-1C, pp. 61-70.Northwest TerritoriesWinter Lake, Regional geology
DS1998-1154
1998
Pesler, A.Pesler, A., et al.The mantle lithosphere beneath the Canadian Cordillera: constraints From the Re Os, Sm neodymium, Lu Hf systematics...Mineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 1155-6.Canada, CordilleraGeochronology, Lherzolites, harzburgites
DS200812-0884
2008
Pesler, A.H.Pesler, A.H., Woodland, A.B., Wolff, J.A.Fast kimberlite ascent rates estimated from hydrogen diffusion profiles in xenolithic mantle olivines from southern Africa.Geochimica et Cosmochimica Acta, Vol. 72, 11, pp. 2711-2722.Africa, South Africa, BotswanaEmplacement
DS200412-2118
2004
PeslierWilliams, H.M., McCammon, C.A., Peslier, Halliday, Teutsch, Levasseur, BurgIron isotope fractionation and the oxygen fugacity of the mantle.Geochimica et Cosmochimica Acta, 13th Goldschmidt Conference held Copenhagen Denmark, Vol. 68, 11 Supp. July, ABSTRACT p.A563.MantleMelting
DS201607-1370
2016
Peslier, A.Peslier, A.Water in the cratonic lithosphere.IGC 35th., Session A Dynamic Earth 1p. AbstractWater
DS202008-1422
2020
Peslier, A.D.McKensie, L., Kilgore, A.H., Peslier, A.D., Brandon, L.A., Schaffer, R.V., Graff, T.G., Agresti, D.G., O'Reilly, S.Y., Griffin, W.L., Pearson, D.G., Hangi, K., Shaulis, B.J.Metasomatic control of hydrogen contents in the layered cratonic mantle lithosphere sampled by Lac de Gras xenoliths in the central Slave craton, Canada.Geochimica et Cosmochimica Acta, in press available, doi.org/101016 /j.gca.2020.07.013 45p. PdfCanada, Northwest Territoriesdeposit - Lac de Gras

Abstract: Whether hydrogen incorporated in nominally anhydrous mantle minerals plays a role in the strength and longevity of the thick cratonic lithosphere is a matter of debate. In particular, the percolation of hydrogen-bearing melts and fluids could potentially add hydrogen to the mantle lithosphere, weaken its olivines (the dominant mineral in mantle peridotite), and cause delamination of the lithosphere's base. The influence of metasomatism on hydrogen contents of cratonic mantle minerals can be tested in mantle xenoliths from the Slave Craton (Canada) because they show extensive evidence for metasomatism of a layered cratonic mantle. Minerals from mantle xenoliths from the Diavik mine in the Lac de Gras kimberlite area located at the center of the Archean Slave craton were analyzed by FTIR for hydrogen contents. The 18 peridotites, two pyroxenites, one websterite and one wehrlite span an equilibration pressure range from 3.1 to 6.6 GPa and include samples from the shallow (? 145 km), oxidized ultra-depleted layer; the deeper (?145-180 km), reduced less depleted layer; and an ultra-deep (? 180 km) layer near the base of the lithosphere. Olivine, orthopyroxene, clinopyroxene and garnet from peridotites contain 30 - 145, 110 - 225, 105 - 285, 2 - 105 ppm H2O, respectively. Within each deep and ultra-deep layer, correlations of hydrogen contents in minerals and tracers of metasomatism (for example light over heavy rare-earth-element ratio (LREE/HREE), high-field-strength-element (HFSE) content with equilibration pressure) can be explained by a chromatographic process occurring during the percolation of kimberlite-like melts through garnet peridotite. The hydrogen content of peridotite minerals is controlled by the compositions of the evolving melt and of the minerals and by mineral/melt partition coefficients. At the beginning of the process, clinopyroxene scavenges most of the hydrogen and garnet most of the HFSE. As the melt evolves and becomes enriched in hydrogen and LREE, olivine and garnet start to incorporate hydrogen and pyroxenes become enriched in LREE. The hydrogen content of peridotite increases with decreasing depth, overall (e.g., from 75 to 138 ppm H2O in the deep peridotites). Effective viscosity calculated using olivine hydrogen content for the deepest xenoliths near the lithosphere-asthenosphere boundary overlaps with estimates of asthenospheric viscosities. These xenoliths cannot be representative of the overall cratonic root because the lack of viscosity contrast would have caused basal erosion of lithosphere. Instead, metasomatism must be confined in narrow zones channeling kimberlite melts through the lithosphere and from where xenoliths are preferentially sampled. Such localized metasomatism by hydrogen-bearing melts therefore does not necessarily result in delamination of the cratonic root.
DS2000-0760
2000
Peslier, A.H.Peslier, A.H., Reisberg, L., Francis, D.Rhenium- Osmium (Re-Os) constraints on harzburgite and lherzolite formation in the lithospheric mantle: a study xenolithsGeochimica et Cosmochimica Acta, Vol. 64, No. 17, Sept. 1, pp. 3061-Northwest Territories, Western Canada, AlbertaXenoliths, Geochronology
DS2002-1251
2002
Peslier, A.H.Peslier, A.H., Luhr, J.F., Post, J.Low water contents in pyroxenes from spinel peridotites of the oxidized, sub arc mantle wedge.Earth and Planetary Science Letters, Vol. 201, 1, July 15, pp. 69-86.MantleMineralogy, Subduction
DS200412-2117
2004
Peslier, A.H.Williams, H.M., McCammon, C.A., Peslier, A.H., Halliday, A.N., Teutsch, N., Levasseur, S., Burg, J-P.Iron isotope fractionation and the oxygen fugacity of the mantle.Science, Vol. 304, 5677, June 11, p. 1656.MantleGeothermobarometry
DS200512-1179
2005
Peslier, A.H.Williams, H.M., Peslier, A.H., McCammon, C., Halliday, A.N., Levasseur, S., Teutsch, N., Burg, J.P.Systematic iron isotope variations in mantle rocks and minerals: the effects of partial melting and oxygen fugacity.Earth and Planetary Science Letters, Advanced in press,MantleMelting
DS200512-1180
2005
Peslier, A.H.Williams, H.M., Peslier, A.H., McCammon, C., Halliday, A.N., Levasseur, S., Teutsch, N., Burg, J.P.Systematic iron isotope variations in mantle rocks and minerals. The effects of partial melting and oxygen fugacity.Earth and Planetary Science Letters, Vol. 235, 1-2, pp. 435-452.MantleGeochronology, melting
DS200612-1084
2006
Peslier, A.H.Peslier, A.H., Luhr, J.F.Hydrogen loss from olivines in mantle xenoliths from Simcoe (USA) and Mexico: mafic alkalic magma ascent rates and water budget of sub-continental lithosphereEarth and Planetary Science Letters, Vol. 242, 3-4, pp. 302-319.United States, CanadaXenoliths - not specific to diamonds
DS200812-0660
2008
Peslier, A.H.Li, ZX., Lee, C-T.A, Peslier, A.H., Lenardic, A., Mackwell, S.J.Water contents in mantle xeonoliths from the Colorado Plateau and vicinity: implications for the mantle rheology and hydration induced thinking of lithosphereJournal of Geophysical Research, Vol. 113, B9, B09210.MantleWater content
DS200812-0885
2008
Peslier, A.H.Peslier, A.H., Woodland, A.B., Wolff, J.A.Fast kimberlite ascent rates estimated from hydrogen diffusion profiles in xenolithic mantle olivines from southern Africa.Geochimica et Cosmochimica Acta, Vol. 72, 11, June 1, pp. 2711-2722.Africa, Lesotho, South AfricaFTIR, magma
DS200812-0886
2008
Peslier, A.H.Peslier, A.H., Woodland, A.B., Wolff, J.A.Fast kimberlite ascent rates estimated from hydrogen diffusion profiles in xenolithic mantle olivines from southern Africa.Geochimica et Cosmochimica Acta, Vol. 72, 11, pp. 2711-2722.Africa, South AfricaKimberlite genesis
DS200812-1325
2008
Peslier, A.H.Zheng-Xue, A.L., Lee, C-T.A., Peslier, A.H., Lenardic, A., Mackwell, S.J.Water contents in mantle xenoliths from the Colorado Plateau and vicinity: implications for mantle rheology and hydration induced thinning of continental lithosph.Journal of Geophysical Research, Vol. 113. B09210United States, Colorado PlateauPeridotite
DS201012-0577
2010
Peslier, A.H.Peslier, A.H., Woodland, A.B., Bell, D.R., Lazarov, M.Olivine water contents in the continental lithosphere and the longevity of cratons.Nature, Vol. 467, Sept. 2, pp. 78-81.MantleGeodynamics - cratons
DS201212-0550
2012
Peslier, A.H.Peslier, A.H., Woodland, A.B., Bell, D.R., Lazarov, M., Lapen, T.J.Metasomatic control of water contents in the Kaapvaal cratonic mantle.Geochimica et Cosmochimica Acta, Vol. 97, pp. 213-246.Africa, South Africa, LesothoDeposit - Finsch, Kimberley, Jagersfontein, Letseng, Liqhobong
DS201412-0015
2014
Peslier, A.H.Armytage, R.M.G., Brandon, A.D., Peslier, A.H., Lapen, T.J.Osmium isotope evidence for Early to Middle Proterozoic mantle lithosphere stabilization and concommitant production of juvenile crust in Dish Hill, CA peridotite xenoliths.Geochimica et Cosmochimica Acta, Vol. 137, pp. 113-133.United States, CaliforniaSCLM, subduction
DS201412-0206
2014
Peslier, A.H.Doucet, L.S., Peslier, A.H., Ionov, D.A.High water contents in the Siberian cratonic mantle linked to metasomatism: an FTOR study of Udachnaya peridotite xenoliths.Geochimica et Cosmochimica Acta, Vol. 137, pp. 159-187.Russia, YakutiaDeposit - Udachnaya
DS201412-0208
2014
Peslier, A.H.Doucet, L.S., Peslier, A.H., Ionov, D.A., Brandon, A.D., Golovin, A.V., Goncharov, A.G., Ashchepkov, I.V.High water contents in the Siberian cratonic mantle linked to metasomatism: an FTIR study of Udachnaya peridotite xenoliths.Geochimica et Cosmochimica Acta, in press availableRussia, SiberiaDeposit - Udachnaya
DS201512-1978
2015
Peslier, A.H.Taylor, L.A., Logvinova, A.M., Howarth, G.H., Liu, Y., Peslier, A.H., Rossman, G.R., Guan, Y., Chen, Y., Sobolev, N.V.Low water contents in diamond mineral inclusions: proto-genetic origin in a dry cratonic lithosphere.Earth and Planetary Science Letters, Vol. 433, pp. 125-132.MantleNAMs Nominally Anhydrous Minerals

Abstract: The mantle is the major reservoir of Earth's water, hosted within Nominally Anhydrous Minerals (NAMs) (e.g., , , and ), in the form of hydrogen bonded to the silicate's structural oxygen. From whence cometh this water? Is the water in these minerals representative of the Earth's primitive upper mantle or did it come from melting events linked to crustal formation or to more recent metasomatic/re-fertilization events? During diamond formation, NAMs are encapsulated at hundreds of kilometers depth within the mantle, thereby possibly shielding and preserving their pristine water contents from re-equilibrating with fluids and melts percolating through the lithospheric mantle. Here we show that the NAMs included in diamonds from six locales on the Siberian Craton contain measurable and variable H2O concentrations from 2 to 34 parts per million by weight (ppmw) in olivine, 7 to 276 ppmw in clinopyroxene, and 11-17 ppmw in garnets. Our results suggest that if the inclusions were in equilibrium with the diamond-forming fluid, the water fugacity would have been unrealistically low. Instead, we consider the H2O contents of the inclusions, shielded by diamonds, as pristine representatives of the residual mantle prior to encapsulation, and indicative of a protogenetic origin for the inclusions. Hydrogen diffusion in the diamond does not appear to have modified these values significantly. The H2O contents of NAMs in mantle xenoliths may represent some later metasomatic event(s), and are not always representative of most of the continental lithospheric mantle. Results from the present study also support the conclusions of Peslier et al. (2010) and Novella et al. (2015) that the dry nature of the SCLM of a craton may provide stabilization of its thickened continental roots.
DS201602-0245
2016
Peslier, A.H.Taylor, L.A., Logvinova, A.M., Howarth, G.H., Liu, Y., Peslier, A.H., Rossman, G.R., Guan, Y., Chen, Y., Sobolev, N.V.Low water contents in diamond mineral inclusions: proto-genetic origin in a dry cratonic lithosphere.Earth and Planetary Science Letters, Vol. 433, pp. 125-132.Russia, AfricaKaapvaal and Siberian SCLMs

Abstract: The mantle is the major reservoir of Earth's water, hosted within Nominally Anhydrous Minerals (NAMs) (e.g., , , and ), in the form of hydrogen bonded to the silicate's structural oxygen. From whence cometh this water? Is the water in these minerals representative of the Earth's primitive upper mantle or did it come from melting events linked to crustal formation or to more recent metasomatic/re-fertilization events? During diamond formation, NAMs are encapsulated at hundreds of kilometers depth within the mantle, thereby possibly shielding and preserving their pristine water contents from re-equilibrating with fluids and melts percolating through the lithospheric mantle. Here we show that the NAMs included in diamonds from six locales on the Siberian Craton contain measurable and variable H2O concentrations from 2 to 34 parts per million by weight (ppmw) in olivine, 7 to 276 ppmw in clinopyroxene, and 11-17 ppmw in garnets. Our results suggest that if the inclusions were in equilibrium with the diamond-forming fluid, the water fugacity would have been unrealistically low. Instead, we consider the H2O contents of the inclusions, shielded by diamonds, as pristine representatives of the residual mantle prior to encapsulation, and indicative of a protogenetic origin for the inclusions. Hydrogen diffusion in the diamond does not appear to have modified these values significantly. The H2O contents of NAMs in mantle xenoliths may represent some later metasomatic event(s), and are not always representative of most of the continental lithospheric mantle. Results from the present study also support the conclusions of Peslier et al. (2010) and Novella et al. (2015) that the dry nature of the SCLM of a craton may provide stabilization of its thickened continental roots.
DS201610-1874
2016
Peslier, A.H.Jean, M.M., Taylor, L.A., Howarth, G.H., Peslier, A.H., Fedele, L., Bodnar, R.J., Guan, Y., Doucet, L.S., Ionov, D.A., Logvinova, A.M., Golovin, A.V., Sobolev, N.V.Olivine inclusions in Siberian diamonds and mantle xenoliths: contrasting water and trace -element contents.Lithos, in press available 11p.Russia, SiberiaDiamond inclusions
DS202011-2047
2020
Peslier, A.H.Kilgore, M.L., Peslier, A.H., Brandon, A.D., Schaffer, L.A., Morris, R.V., Graff, T.G., Agresti, D.G., O'Reilly, S.Y., Griffin, W.L., Pearson, D.G., Barry, K.G., Shaulis, J.Metasomatic control of hydrogen contents in the layered cratonic mantle lithosphere sampled by Lac de Gras xenoliths in the central Slave Craton, Canada.Geochimica et Cosmochimica Acta, Vol. 286, pp. 29-83. pdfCanada, Northwest Territoriesxenoliths

Abstract: Whether hydrogen incorporated in nominally anhydrous mantle minerals plays a role in the strength and longevity of the thick cratonic lithosphere is a matter of debate. In particular, the percolation of hydrogen-bearing melts and fluids could potentially add hydrogen to the mantle lithosphere, weaken its olivines (the dominant mineral in mantle peridotite), and cause delamination of the lithosphere's base. The influence of metasomatism on hydrogen contents of cratonic mantle minerals can be tested in mantle xenoliths from the Slave Craton (Canada) because they show extensive evidence for metasomatism of a layered cratonic mantle. Minerals from mantle xenoliths from the Diavik mine in the Lac de Gras kimberlite area located at the center of the Archean Slave craton were analyzed by FTIR for hydrogen contents. The 18 peridotites, two pyroxenites, one websterite and one wehrlite span an equilibration pressure range from 3.1 to 6.6 GPa and include samples from the shallow (?145?km), oxidized ultra-depleted layer; the deeper (?145-180?km), reduced less depleted layer; and an ultra-deep (?180?km) layer near the base of the lithosphere. Olivine, orthopyroxene, clinopyroxene and garnet from peridotites contain 30-145, 110-225, 105-285, 2-105?ppm H2O, respectively. Within each deep and ultra-deep layer, correlations of hydrogen contents in minerals and tracers of metasomatism (for example light over heavy rare-earth-element ratio (LREE/HREE), high-field-strength-element (HFSE) content with equilibration pressure) can be explained by a chromatographic process occurring during the percolation of kimberlite-like melts through garnet peridotite. The hydrogen content of peridotite minerals is controlled by the compositions of the evolving melt and of the minerals and by mineral/melt partition coefficients. At the beginning of the process, clinopyroxene scavenges most of the hydrogen and garnet most of the HFSE. As the melt evolves and becomes enriched in hydrogen and LREE, olivine and garnet start to incorporate hydrogen and pyroxenes become enriched in LREE. The hydrogen content of peridotite increases with decreasing depth, overall (e.g., from 75 to 138?ppm H2O in the deep peridotites). Effective viscosity calculated using olivine hydrogen content for the deepest xenoliths near the lithosphere-asthenosphere boundary overlaps with estimates of asthenospheric viscosities. These xenoliths cannot be representative of the overall cratonic root because the lack of viscosity contrast would have caused basal erosion of lithosphere. Instead, metasomatism must be confined in narrow zones channeling kimberlite melts through the lithosphere and from where xenoliths are preferentially sampled. Such localized metasomatism by hydrogen-bearing melts therefore does not necessarily result in delamination of the cratonic root.
DS2001-0140
2001
PesonenBuchan, K.L., Ernst, Hamilton, Mertanen, Pesonen, ElmingRodinia: the evidence from integrated paleomagnetism and uranium-lead (U-Pb) geochronologyPrecambrian Research, Vol. 110, pp. 9-32.GlobalGeochronology
DS1983-0478
1983
Pesonen, L.J.Nevanlinna, H., Pesonen, L.J.Late Precambrian Keweenawan Asymmetric Polarities As Analyzed by Axial Offset Dipole Geomagnetic Models.Journal of Geophysical Research, SECT. B, Vol. 88, No. 1, PP. 645-658.GlobalMid-continent, Geophysics
DS200512-0848
2004
Pesonen, L.J.Pesonen, L.J., Elbra, T.Supercontinents during the Proterozoic - a paleomagnetic survey.Geological Society of America Annual Meeting ABSTRACTS, Nov. 7-10, Paper 82-5, Vol. 36, 5, p. 206.Kenorland, Hudsonland, Columbia, RodiniaPaleomagnetism
DS200612-0755
2006
Pesonen, L.J.Kuusisto, M., Kukkonen, L.T., Heikkinen, P., Pesonen, L.J.Lithological interpretation of crustal composition in the Fennoscandian Shield with seismic velocity data.Tectonophysics, in pressEurope, Finland, FennoscandiaGeophysics - seismics, wide-angle reflection
DS201012-0578
2010
Pesonen, L.J.Pesonen, L.J.Importance of mafic dyke swarms in tracing the tectonic histories of continents and their building blocks.International Dyke Conference Held Feb. 6, India, 1p. AbstractGlobalTectonics
DS201212-0466
2012
Pesonen, L.J.Mertanen, S., Pesonen, L.J.Paleo-Mesoproterozoic assemblages of continents: paleomagnetic evidence for near Equatorial supercontinents.Springer Lecture Notes in Earth Sciences From the Earth's core to Outer space, editor Haapala, I., Vol. 137, pp. 11-35.GlobalSupercontinents
DS201811-2601
2018
Pesonen, L.J.Piispa, E.J., Smirnov, A.V., Pesonen, L.J., Mitchell, R.H.Paleomagnetism and geochemistry of ~1144.-Ma lamprophyre dikes, northwestern Ontario: implcations for the North American polar wander and plate velocities.Journal of Geophysical Research: Solid Earth, Vol. 123, 8, pp. 6195-6214.Canada, Ontariogeochronology

Abstract: Similar to a magnetic tape, rocks can retain the direction of ancient Earth's magnetic field. Scientists use this record (known as paleomagnetism) to reconstruct past positions of continents and to decipher the geological history of our planet. We investigated paleomagnetism and chemical composition of the ~1.14 Ga?old intrusive rocks called lamprophyres exposed in Northwestern Ontario (Canada). We found that the paleomagnetic field directions recorded in lamprophyres are indistinguishable from those recorded by another similar age suite of basaltic intrusions called the Abitibi dikes, from the same area. The combined data from these rocks allowed us to constrain the position of an ancient supercontinent called Laurentia at ~1.14 billions of years ago more accurately than it was possible before. Our results convincingly show that, during that time, Laurentia moved with a velocity comparable to present?day plate velocities, before switching to an extremely rapid motion approximately 35 millions of years later. The lamprophyre and Abitibi rocks also share similar chemical signatures, close to those observed for ocean island basalts (e.g., Hawaii). These observations support the hypothesis that a failed ocean opening attempt called the North American Midcontinent Rift was instigated by the arrival of a hot mantle material upwelling to the Earth surface.
DS1993-0817
1993
Pesowski, M.King, A., Pesowski, M.Environmental applications of surface and airborne geophysicsThe Canadian Mining and Metallurgical Bulletin (CIM Bulletin), Vol. 86, No. 966, January pp. 58-67GlobalGeophysics -airborne, Evironmental
DS201608-1419
2016
Pessanha, I.Maia, M., Sichel, S., Briais, A., Brunelli, D., Ligi, M., Ferreira, N., Campos, T., Mougel, B., Brehme, I., Hemond, C., Motoki, A., Moura, D., Scalabrin, C., Pessanha, I., Alves, E., Ayres, A., Oliveira, P.Extreme mantle uplift and exhumation along a transpressive transform fault.Nature Geoscience, Vol. 9, 8, pp. 619-623.MantleRidges

Abstract: Mantle exhumation at slow-spreading ridges is favoured by extensional tectonics through low-angle detachment faults1, 2, 3, 4, and, along transforms, by transtension due to changes in ridge/transform geometry5, 6. Less common, exhumation by compressive stresses has been proposed for the large-offset transforms of the equatorial Atlantic7, 8. Here we show, using high-resolution bathymetry, seismic and gravity data, that the northern transform fault of the St Paul system has been controlled by compressive deformation since ~10?million years ago. The long-lived transpression resulted from ridge overlap due to the propagation of the northern Mid-Atlantic Ridge segment into the transform domain, which induced the migration and segmentation of the transform fault creating restraining stepovers. An anticlockwise change in plate motion at ~11?million years ago5 initially favoured extension in the left-stepping transform, triggering the formation of a transverse ridge, later uplifted through transpression, forming the St Peter and St Paul islets. Enhanced melt supply at the ridge axis due to the nearby Sierra Leone thermo chemical anomaly9 is responsible for the robust response of the northern Mid-Atlantic Ridge segment to the kinematic change. The long-lived process at the origin of the compressive stresses is directly linked to the nature of the underlying mantle and not to a change in the far-field stress regime.
DS202101-0027
2020
Pessano, P.C.Pessano, P.C., Ganade, C.E., Tupinamba, M., Teixeira, W.Updated map of the mafic dike swarms of Brazil based on airborne geophysical data.Journal of South American Earth Sciences, in press available, 16p. PdfSouth America, Brazilgeophysics

Abstract: Identification of mafic dike swarms and LIPs (Large Igneous Provinces) are of vital importance in geologic history because they provide information on geodynamics, mantle geochemistry, and paleomagnetism. These data provide key information for paleogeographic reconstructions with the aid of barcode matches and precise radiometric ages. Considering such issues, the Brazilian Precambrian shield can be used as a case for refining the cartography of the relevant intraplate activity (e.g., dikes, sills, flood basalts) in space and time. This work presents an updated map of Brazilian mafic dike swarms produced from airborne geophysical maps (Series 1000 - Geological Survey of Brazil). Linear and strong anomalies found on aeromagnetic maps using First Vertical Derivative of the Magnetic Field and Amplitude of the Analytic Signal were mapped on a GIS platform. The obtained data were compared to ternary radiometric maps and geological maps in order to exclude those that do not correspond to mafic dikes. The remaining structures - those believed to represent mafic dikes - were classified based on data compiled from the literature. The updated map exhibits more than 5000 elements, including dikes and magmatic suites, in which about 75% were geologically identified and divided into 60 dike swarms and 10 igneous suites and/or units. The dikes were grouped into sixteen extensional episodes from the Archean to the Cenozoic, although some are related to extension/transtension domains within regional compressive zones akin to orogenic settings. The most frequent records refer to the Proterozoic, representing intraplate episodes, some of them consistent with LIPs. The dataset also includes a large record of the Mesozoic age, which corresponds to major LIP events related to the opening of the Atlantic Ocean and the fragmentation of Gondwana.
DS200612-1085
2006
Pesslier, A.H.Pesslier, A.H., Luhr, J.F., Woodland, A.B., Wolff, J.A., Meen, J.K.Estimating alkali basalt and kimberlite magma ascent rates using H diffusion profiles in xenolithic mantle olivine.Geochimica et Cosmochimica Acta, Vol. 70, 18, 1, p. 19, abstract only.MantleMagmatism
DS1995-0129
1995
Petard, J.Becquer, T., Bourdon, E., Petard, J.Disponibilite du nickel le long d'une toposequence de sols developpes surroches ultramafiques N. CaledoniaC.r. Academy Of Science Paris, Vol. 321, 11a, pp. 585-592New CaledoniaNickel, Ultramafics
DS1995-1066
1995
Petchnikov, V.A.Lavrova, L.D., Petchnikov, V.A., Petrova, M.A., EkimovaNew genetic type of diamond deposits: geological pecularities and originProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 311-313.Russia, KazakhstanMetamorphic, Deposit -Kumdykolskoye
DS1995-1487
1995
Petchnikov, V.A.Petchnikov, V.A.Structure and pecularities of formation the Kumdykolskoye depositProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 439-440.Russia, KazakhstanStructure, Deposit -Kokchetav
DS201312-0702
2013
PetDBPetDBMantle xenolith dat a ( formerly Deep Lithosphere Dat aset).PetDB, Noted in Geochemistry NewsMantleMineral chemistry
DS202009-1674
2020
Petecki, Z.Wiszniewska, J.B., Krzeminska, E., Petecki, Z., Grababarczyk, A., Demaiffe, D.Geophysical and petrological constraints for ultramafic-alkaline-carbonatite magmatism in the Tajno intrusion, NE Poland.Goldschmidt 2020, 1p. AbstractEurope, Polandcarbonatites

Abstract: This Tajno alkaline massif (together with the nearby E?k and Pisz intrusions) occurs beneath a thick Mesozoic- Cenozoic sedimentary cover. It has first been recognized by geophysical (magnetic and gravity) investigations, then directly by deep drilling (12 boreholes down to 1800 m). The main rock types identified as clinopyroxenites, syenites, carbonatites, have been cut by later multiphase volcanic /subvolcanic dykes. This massif was characterized as a differentiated ultramafic, alkaline and carbonatite complex, quite comparable to the numerous massifs of the Late Devonian Kola Province of NW Russia [1,2]. Recent geochronological data (U-Pb on zircon from an albitite and Re-Os on pyrrhotite from a carbonatite) indicate that the massif was emplaced at ca. 348 Ma (Early Carboniferous). All the rocks, but more specifically the carbonatites, are enriched in Sr, Ba and LREE, like many carbonatites worldwide but depleted in high field strength elements (Ti, Nb, Ta, Zr). The initial 87Sr/86Sr (0.70370 to 0.70380) and ?Nd(t) (+3.3 to +0.7) isotopic compositions of carbonatites plot in the depleted quadrant of the Nd-Sr diagram, close to “FOcal ZOne” (FOZO) deep mantle domain [1]. The Pb isotopic data (206Pb/204Pb <18.50) do not point to an HIMU (high U/Pb) source. The ranges of C and O stable isotopic compositions of the carbonatites are quite large; some data plot in (or close to) the “Primary Igneous Carbonatite” box while others extend to much higher, typically crustal ?18O and ?13C values.
DS1992-0820
1992
Petelina, N.A.Kaminsky, F.V., Kolesnikov, S.K., Petelina, N.A., Khamani, M., et al.Minerals associated with diamond in the Algerian Sahara.(Russian)Mineralogischeskiy Zhurnal, (Russian), Vol. 14, No. 3, pp. 15-25AlgeriaMineralogy, Silet
DS200812-0887
2008
Peter, B.W.Peter, B.W.The rock mechanics of kimberlite volcanic pipe excavation.Journal of Volcanology and Geothermal Research, Vol. 174, 1-3, pp. 29-39.GlobalStructure, stress, diatreme, breccia, dilution
DS201212-0833
2012
Peter, D.Zhu, H., Bozdag, E., Peter, D., Tromp, J.Structure of the European upper mantle revealed by adjoint tomography.Nature Geoscience, Vol. 5, July, pp. 493-497.EuropeHotspots
DS1991-1336
1991
Peter, G.Peter, G., Klopping, F.J., Carter, W.E., Dewhurst, W.T.Absolute gravity reference sites in the United StatesGeophysics: the Leading Edge of Exploration, July, pp. 43-48United StatesGeophysics, Gravity sites
DS2003-1070
2003
Peter, J.Peter, J., Bleeker, W., Hulbert, J., Kerr, D., Ernst, R., Knight, R., Wright, D.Slave Province minerals and geosciemce compilation and synthesis project31st Yellowknife Geoscience Forum, p. 79. (abst.)Nunavut, Northwest TerritoriesOverview
DS200412-1533
2003
Peter, J.Peter, J., Bleeker, W., Hulbert, J., Kerr, D., Ernst, R., Knight, R., Wright, D., Anglin, L.Slave Province minerals and geosciemce compilation and synthesis project.31st Yellowknife Geoscience Forum, p. 79. (abst.)Canada, Nunavut, Northwest TerritoriesOverview
DS200512-0117
2005
Peter, P.Brown, O.H., Utting, D.J., Little, E.C., Grunsky, E.C., Harris, J., Peter, P.Remote predictive mapping of surficial geology in Nunavut using supervised classification techniques of Land sat and RADARSAT I data.GAC Annual Meeting Halifax May 15-19, Abstract 1p.Canada, NunavutRemote sensing
DS1990-0796
1990
PetermanKamineni, D.C., Stone, PetermanEarly Proterozoic deformation in the western Superior Province, CanadianShield.Geological Society of America (GSA) Bulletin., Vol. 102, pp. 1623-34.Ontario, ManitobaKenoran Orogeny
DS1960-1008
1968
Peterman, Z.E.Peterman, Z.E., Hedge, C.E., Braddock, W.A.Age of Precambrian Events in the Northeast Front Range, Colorado.Journal of Geophysical Research, Vol. 73, PP. 2277-2296.United States, Colorado, State Line, Rocky MountainsDiatreme
DS1970-0692
1973
Peterman, Z.E.Ghent, E.D., Peterman, Z.E., Coleman, R.G.Sr 87/ Sr 86, Potassium, Sodium, Rubidium, and Strontium in SOME ECLOGITES and ASSOCIATED BASALTS from CALIFORNIA and SOUTHWESTERN OREGON.United States Geological Survey (USGS) Journal of RES., Vol. 1, No. 6, PP. 643-647.United States, California, Oregon, West CoastEclogites, Basalts, Strontium
DS1984-0636
1984
Peterman, Z.E.Schulz, K.J., Laberge, G.L., Sims, P.K., Peterman, Z.E., Klasner.The Volcanic Plutonic Terrane of Northern Wisconsin: Implications for Early Proterozoic Tectonism, Lake Superior Region.Geological Association of Canada (GAC), Vol. 9, P. 103. (abstract.).MichiganMid-continent
DS1985-0524
1985
Peterman, Z.E.Peterman, Z.E., Zartman, R.E.The Early Proterozoic Trans-hudson Orogen in the Northern Great Plains of the United States.6th. International Conference Basement Tectonics, Held Sante Fe, Septem, P. 30. (abstract.).United States, Rocky Mountains, North Dakota, South Dakota, Montana, WillisGeotectonics
DS1985-0618
1985
Peterman, Z.E.Sims, P.K., Peterman, Z.E.Early Proterozoic Tectonics in the North Central United States.Geological Society of America (GSA), Vol. 17, No. 7, P. 718. (abstract.).United States, Central States, Nebraska, Kansas, MissouriGeochronology, Midcontinent
DS1986-0740
1986
Peterman, Z.E.Sims, P.K., Peterman, Z.E.Early Proterozoic Central Plains orogen: a major buried structure in The north central United StatesGeology, Vol. 14, No. 6, June pp. 488-491MidcontinentTectonics
DS1989-0082
1989
Peterman, Z.E.Barovich, K.M., Patchett, P.J., Peterman, Z.E., Sims, P.K.neodymium isotopes and the origin of 1.9-1.7 Ga Penokean continental crust of the Lake Superior regionGeological Society of America (GSA) Bulletin, Vol. 101, No. 3, March pp. 333-338OntarioGeochronology, Penokean-Lake Superior
DS1989-1201
1989
Peterman, Z.E.Peterman, Z.E., Day, W.Early Proterozoic activity on Archean faults in the Western Superior Province- evidence from pseudotachyliteGeology, Vol. 17, No. 12, December pp. 1089-1092OntarioTectonics, Structure-faults Superior province
DS1989-1395
1989
Peterman, Z.E.Sims, P.K., Van Schmus, W.R., Schulz, K.J., Peterman, Z.E.Tectono-stratigraphic evolution of the early Proterozoic Wisconsin magmatic terranes of the Penokean OrogenCanadian Journal of Earth Sciences, Vol. 26, No. 10, October pp. 2145-2158WisconsinStratigraphy, Orogeny -Penokean
DS1989-1396
1989
Peterman, Z.E.Sims, P.K., Van Schmus, W.R., Schulz, K.J., Peterman, Z.E.Tectono-stratigraphic evolution of the Early Proterozoic Wisconsin magmatic terranes of the Penokean OrogenCanadian Journal of Earth Sciences, Vol. 26, No. 10, October pp. 2145-2158WisconsinTectonics
DS1991-1591
1991
Peterman, Z.E.Sims, P.K., Peterman, Z.E., Hildenbrand, T.G., Mahan, S.Precambrian basement map of the Trans-Hudson Orogen and adjacent northern Great Plains, United States (US)United States Geological Survey (USGS), Map I 2214, 1: 1, 000, 000 $ 3.10Minnesota, Montana, Nebraska, WyomingPrecambrian, Map
DS1992-1360
1992
Peterman, Z.E.Seifert, K.E., Peterman, Z.E., Thieben, S.E.Possible crustal contamination of Midcontinent Rift igneous rocks: examples from the Mineral Lake intrusions, WisconsinCanadian Journal of Earth Sciences, Vol. 29, No. 6, June pp. 1140-1153WisconsinIgneous rocks, Tectonics
DS1992-1361
1992
Peterman, Z.E.Seifert, K.E., Peterman, Z.E., Thieben, S.E.Possible crustal contamination of Midcontinent Rift igneous rocks: examples from the Mineral Lake intrusions, WisconsinCanadian Journal of Earth Sciences, Vol. 29, No. 6, June pp. 1140-1153WisconsinMidcontinent Rift, Igneous rocks
DS1993-0210
1993
Peterman, Z.E.Cannon, W.F., Peterman, Z.E., Sims, P.K.Crustal scale thrusting and origin of the Montreal River monocline- a 35 KM thick cross section of the Midcontinent RiftTectonics, Vol. 12, No. 3, June pp. 728-744Wisconsin, MichiganTectonics, Structure
DS1994-1364
1994
Peterman, Z.E.Percival, J.A., Peterman, Z.E.rubidium-strontium (Rb-Sr) biotite and whole rock dat a from the Kapuskasing uplift and their bearing on the cooling and exhumationCanadian Journal of Earth Sciences, Vol. 31, No. 7, July pp. 1172-1181.OntarioGeochronology, Tectonics -Kapuskasing uplift
DS200512-0997
2004
Peterman, Z.E.Sims, P.K., Peterman, Z.E., Anderson, E.D.Early tectonic evolution of the North America continent - a model invoking subcontinental mantle deformation.Geological Society of America Annual Meeting ABSTRACTS, Nov. 7-10, Paper 244-2, Vol. 36, 5, p. 567.United States, CanadaTectonics
DS2003-1071
2003
Petermann, M.Petermann, M., Hirschmann, M.M.Anhydrous partial melting experiments on MORB like eclogite: phase relations, phaseJournal of Petrology, Vol. 44, 12, pp. 2173-2202.MantleMetasomatism - eclogite
DS200412-1534
2003
Petermann, M.Petermann, M., Hirschmann, M.M.Anhydrous partial melting experiments on MORB like eclogite: phase relations, phase compositions and mineral melt partitioning oJournal of Petrology, Vol. 44, 12, pp. 2173-2202.MantleMetasomatism - eclogite
DS201412-0680
2010
PetersPeters, NizamDiamond inclusions.Institute of Diamond Cutting, P.O. Box 4067 Deerfield Beach Fl 33442, diamondschool.com 208 p. $135 Plus s & HTechnologyBook - inclusions
DS201412-0173
2014
Peters, B.J.Day, J.M.D., Peters, B.J., Janney, P.E.Oxygen isotope systematics of South African olivine melilitites and implications for HIMU mantle reservoirs.Lithos, Vol. 202-203, pp. 76-84.Africa, South AfricaMelilitite
DS1981-0274
1981
Peters, D.Lutter, W., Peters, D., Mooney, W.D., Healy, J.H.Crustal Structure of the Mississippi Embayment; Axial ProfilEos, Vol. 62, No. 45, P. 1046. (abstract.).GlobalMid-continent
DS1982-0494
1982
Peters, D.Peters, D., Mooney, W.D., Andrews, M.C., Ginzburg, A.The Deep Crustal Structure of the Northern Mississippi Embayment.Eos, Vol. 63, No. 45, P. 1118. (abstract.).GlobalMid-continent
DS2002-0677
2002
Peters, D.C.Hauff, P.L., Coulter, D., Koll, G., Peters, D.C., Peppin, W.A.An overview of hyper spectral remote sensing as applied to precious metals and diamond deposits.11th. Quadrennial Iagod Symposium And Geocongress 2002 Held Windhoek, Abstract p. 27.GlobalRemote sensing - hyperspectral
DS1975-0589
1977
Peters, E.R.Norman, J.W., Price, N.J., Peters, E.R.Photo geological Fracture Trace Study of Controls of Kimberlite Intrusion in Lesotho Basalts.Institute of Mining and Metallurgy. Transactions, Vol. 86, PP. B78-90.LesothoTectonics, Photogeology
DS1993-1223
1993
Peters, J.W.Peters, J.W., Kesse, G.O., Acquah, P.C.Regional trends in African geology. Proceedings 9th. International Geol. Conference held Accra 1992Geological Society Africa/Ghana, 420pGhana, Uganda, Tanzania, Zaire, Togo, Ivory CoastGold, Tarkian, Birimian, Proterozoic, Mozambique, Book -Table of contents
DS201812-2862
2018
Peters, M.H.Peters, M.H., Henderson, J.Bridging the gap through care and collaboration: before closure and after production. Snap Lake2018 Yellowknife Geoscience Forum , pp. 60-61. abstractCanada, Northwest territoriesdeposit - Snap Lake

Abstract: Wikipedia defines “Care and Maintenance” as a term used in the mining industry to describe processes and conditions on a closed mine site where there is potential to recommence operations at a later date. During a care and maintenance phase, production is stopped but the site is managed to ensure it remains in a safe and stable condition. De Beers Canada Inc. - Snap Lake Mine entered the Care and Maintenance phase after production ceased in December 2015. The partnership with Det'on Cho Corporation provides for a sustainable execution of care and maintenance activities, taking into consideration approved work plans, mine health and safety considerations and emergency response plans. The mine is currently in its third year of care and maintenance. After exploring the potential sale of the asset and assessing the possibility of reopening the mine, the decision to proceed toward closure was taken in December 2017, ushering Snap Lake into a period of extended care and maintenance (ECM) while a closure plan is developed and finalized. Activities during ECM include monitoring of water quality and other environmental parameters, collecting/treating effluent and making sure that water leaving the site meets water license compliance. Physical infrastructure such as the airstrip, roads, buildings, processed kimberlite containment facilities and associated surface water infrastructure such as sumps, pumps and channels need to be kept in a safe and operable condition. Camp infrastructure such as generators and machinery and equipment are also part of the Care and Maintenance program. Collaboration between the De Beers Canada owner's team and Det'on Cho Corporation resulted in the safe execution of the 2018 work plan which included freshet operations, continued progressive reclamation work, monitoring and maintenance activities. After a trial-run of reduced camp occupancy in the winter of 2017, the site was fully winterized and demobilized in September 2018 to allow for monthly site visits for the duration of the winter and planning for a spring 2019 start-up.
DS201912-2812
2019
Peters, M.H.Peters, M.H.Extended care and maintenance and zero occupancy at Snap Lake mine: an update.Yellowknife Forum NWTgeoscience.ca, abstract volume p.69.Canada, Northwest Territoriesdeposit - Snap Lake

Abstract: The Snap Lake Mine is a former underground diamond mine operated by De Beers Canada Inc.( De Beers), located about 220 km northeast of Yellowknife in the Northwest Territories. The Snap Lake Mine operated from 2008 to 2015 and De Beers submitted the Final Closure and Reclamation Plan for the mine. The mine is currently in it fourth year of being managed in a state of Extended Care and Maintenance (ECM). Activities during ECM include monitoring of water quality and other environmental parameters, collecting and treating effluent and making sure that water leaving the site meets water license requirements. Physical infrastructure such as the airstrip, roadways, buildings, processed kimberlite containment facilities and associated surface water infrastructure such as pumps, sumps and channels need to be kept in a safe and operable condition. After a trail-run of reduced camp occupancy in 2017, the site was fully winterized and demobilized in September 2018. This update will review the first seasonal zero occupancy at Snap Lake, as well as the work completed in spring/summer of 2019.
DS201912-2813
2019
Peters, M.H.Peters, M.H., Mensah-Yeboah, F., Milne, I.Remote monitoring at Snap Lake mine.Yellowknife Forum NWTgeoscience.ca, abstract volume p. 70.Canada, Northwest Territoriesdeposit - Snap Lake

Abstract: The Snap Lake Mine is a former underground diamond mine operated by De Beers Canada Inc. (De Beers), located about 220 km northeast of Yellowknife in the Northwest Territories. The Snap Lake mine operated from 2008 to 2015, and entered a Care and Maintenance mode in December 2015. The mine is currently entering its fourth year of being managed in this Extended Care and Maintenance phase. In order to ensure continual remote monitoring of certain key geotechnical, meteorological and air quality instrumentation and to enable visual observation of key infrastructure, work was done in 2018 to integrate new and existing monitoring instrumentation into the existing Campbell Scientific PakBus network. In this presentation De Beers will share a summary of this work, with the emphasis on the type of technology, detail of installation and integration of systems between the various pieces of instrumentation. First we will discuss installation of the 5 data collection stations that relay geotechnical instrumentation information. The data collection system at each of the 5 stations consists of a solar panel, battery, data logger, multiplexor and short-wave radio. To enable redundancy, a manual data collection via USB was added, in the event that remote communication with the stations is lost. Second, an overview of the installation of camera monitoring stations as well as the communications protocol used for the integration of the weather and ambient air quality data transmitted via satellite will be presented. While the focus will be on the technology and systems used for remote monitoring, and not the actual monitoring results per se, it is our intention to share this and some of the successes and challenges experienced during the first year of remote monitoring during zero occupancy conditions.
DS201608-1433
2016
Peters, N.Peters, N.Rough diamonds, a practical guide. American Institute of Diamond Cutting Dearfield Beach, Florida USA, ISBN 978-0966585490 274p. Approx. US $ 165.00TechnologyBook
DS201312-0044
2013
Peters, S.Ayuso, R., Tucker, R., Peters, S., Foley, N., Jackson, J., Robinson, S., Bove, M.Preliminary radiogenic isotope study on the origin of the Khanneshin carbonatite complex, Helmand Province, Afghanistan.Journal of Geochemical Exploration, Vol. 133, pp. 6-14.AfghanistanCarbonatite
DS201902-0284
2019
Peters, S.E.Keller, C.B., Husson, J.M., Mitchell, R.N., Bottke, W.F., Gernon, T.M., Boehnke, P., Bell, E.A., Swanson-Hysell, N.L., Peters, S.E.Neoproterozoic glacial origin of the Great Unconformity.PNAS, pnas.org/cqi/doi/10.1073/ pnas.1804350116 10p.Mantlegeomorphology

Abstract: The Great Unconformity, a profound gap in Earth’s stratigraphic record often evident below the base of the Cambrian system, has remained among the most enigmatic field observations in Earth science for over a century. While long associated directly or indirectly with the occurrence of the earliest complex animal fossils, a conclusive explanation for the formation and global extent of the Great Unconformity has remained elusive. Here we show that the Great Unconformity is associated with a set of large global oxygen and hafnium isotope excursions in magmatic zircon that suggest a late Neoproterozoic crustal erosion and sediment subduction event of unprecedented scale. These excursions, the Great Unconformity, preservational irregularities in the terrestrial bolide impact record, and the first-order pattern of Phanerozoic sedimentation can together be explained by spatially heterogeneous Neoproterozoic glacial erosion totaling a global average of 3-5 vertical kilometers, along with the subsequent thermal and isostatic consequences of this erosion for global continental freeboard.
DS202111-1780
2021
Peters, S.E.Peters, S.E., Walton, C.R., Husson, J.M., Quinn, D.P., Shorttle, O., Keller, C.B., Gaines, R.R.Igneous rock area and age in continental crust.Geology, Vol. 49, pp. 1235-1239. pdfGlobalgeochronology

Abstract: Rock quantity and age are fundamental features of Earth's crust that pertain to many problems in geoscience. Here we combine new estimates of igneous rock area in continental crust from the Macrostrat database (https://macrostrat.org/) with a compilation of detrital zircon ages in order to investigate rock cycling and crustal growth. We find that there is little or no decrease in igneous rock area with increasing rock age. Instead, igneous rock area in North America exhibits four distinct Precambrian peaks, remains low through the Neoproterozoic, and then increases only modestly toward the recent. Peaks in Precambrian detrital zircon age frequency distributions align broadly with peaks in igneous rock area, regardless of grain depositional age. However, detrital zircon ages do underrepresent a Neoarchean peak in igneous rock area; young grains and ca. 1.1 Ga grains are also overrepresented relative to igneous area. Together, these results suggest that detrital zircon age distributions contain signatures of continental denudation and sedimentary cycling that are decoupled from the cycling of igneous source rocks. Models of continental crustal evolution that incorporate significant early increase in volume and increased sedimentation in the Phanerozoic are well supported by these data.
DS201212-0737
2012
Peters, S.G.Tucker, R.D., Belkin, H.E., Schulz, K.J., Peters, S.G., Horton, F.A major light rare earth element (LREE) resource in the Khanneshin carbonatite complex, southern Afghanistan.Economic Geology, Vol. 107, 2, pp. 197-208.Europe, AfghanistanCarbonatite
DS201412-0934
2014
Peters, S.G.Tucker, R.D., Roig, J.Y., Moine, B., Delor, C., Peters, S.G.A geological synthesis of the Precambrian shield in Madagascar.Journal of African Earth Sciences, Vol. 94, pp. 9-30.Africa, MadagascarGeology
DS202104-0566
2021
Peters, S.T.J.Branchetti, M., Zepper, J.C.O., Peters, S.T.J., Koornneef, J.M., Davies, G.Multi-stage formation and destruction in Kimberley harzburgitic xenoliths, South Africa.Lithos, in press available, 57p. PdfAfrica, South Africadeposit - Kimberley

Abstract: Thirty-nine garnet harzburgites from Kimberley in the Kaapvaal Craton (South Africa) were studied to constrain the origin, age and evolution of sub-cratonic lithospheric mantle (SCLM). In order to avoid chemical overprinting by recent metasomatism, only garnet harzburgites that appeared clinopyroxene-free to the naked eye were sampled. The majority of garnets were, however, in equilibrium with clinopyroxene (24 of 39). Whole rock and mineral major-trace element geochemistry and garnet Sr-Nd-Hf isotope data are presented. Equilibration pressures range from 3.8-6.1?GPa, indicating the harzburgites were derived from a large portion of the SCLM (~115-185?km). High olivine Mg# (~93.4, n?=?39) and low whole rock heavy rare earth elements (HREE) contents are consistent with large degrees of partial melting (>45%) and garnet exhaustion leaving a dunitic residue with olivine ?90%, orthopyroxene ?10% and HREE <0.01 times chondrite. Mineral modes, whole rock Al2O3 (0.5-3.2?wt%) and SiO2 (43.1-49.1?wt%), however, indicate heterogeneous re-introduction of garnet (?13%) and orthopyroxene (?50%). Harzburgites with high garnet and relatively low orthopyroxene modes (mostly ~7-13% and?~?9-30%; n?=?6) are characterised by mildly sinusoidal garnet REE patterns (Tbsingle bondDy minimum and high HREE) and Archaean depleted Hf TDM ages (2.7-3.3?Ga; ?Hfe: +190 to +709). In contrast, harzburgites with high orthopyroxene and relatively low garnet and modes (~1.5-7.5% and?~?25-50%; n?=?19) are characterised by highly sinuous REE patterns (Hosingle bondYb minimum and low HREE) and Proterozoic enriched Hf TDM ages (0.7-1.6?Ga; ?Hfe: ?16 to +6). It is inferred that Archaean G10 garnet re-introduction caused a significant increase in HREE, making melt depletion models based on HREE inaccurate. Orthopyroxene addition, a few hundred million years later, most likely at ~2.7?Ga and associated with Ventersdorp magmatic activity, caused partial consumption of garnet and olivine, and changed garnet compositions leading to: 1) Cr/Al ratio increase; 2) HREE decrease; 3) more sinusoidal REE patterns; and 4) un-radiogenic 176Hf/177Hf. Garnets define a Lusingle bondHf isochron age of 2702?±?64?Ma (?Hfi?=?+44, n?=?31), which is interpreted as a consequence of partial isotopic equilibrium within the SCLM and mixing of the garnet- and orthopyroxene-rich metasomatic components. The low LILE contents and absence of Nbsingle bondTa anomalies are consistent with modal metasomatism caused by intra-plate magmatism. In addition, the REE signatures of metasomatic agents in equilibrium with the garnets suggest that carbonatitic melts and SiO2-rich hydrous melts were responsible for re-introduction of garnet and orthopyroxene, respectively. Srsingle bondNd isotope systematics were disrupted associated with kimberlite magmatism (Nd isochron: 217?±?58?Ma, ?Ndi?=?+4; n?=?34), consistent with recent G10 garnet transformation into G9 garnets (Ca?+?Fe-enriched). This event may have caused garnet addition (up to 1%), suggesting that garnet was formed or destroyed in at least 4 different events: i) initial extensive polybaric melting, ii) asthenospheric melts re-introducing the bulk of the garnet, iii) orthopyroxene addition and garnet loss, all in the Archaean, and iv) minor garnet addition possibly related to recent kimberlite magmatism prior to eruption.
DS1991-1337
1991
Peters, T.J.Peters, T.J., Nicolas, A., Coleman, R.G.Ophiolite genesis and evolution of the oceanic lithosphere. Proceedings of conference held Oman Jan. 7-18, 1990Kluwer Publ, 900pOman, East Pacific Rise, Cyprus, Japan, Morocco, NewfoundlandOphiolites, genesis, mantle, magmatic, hydrothermal, tecton, Table of contents
DS1992-1188
1992
Petersen, E.U.Petersen, E.U., McMillan, D.Electron microprobe mineral analysis: applications in exploration and minedevelopmentMining Engineering, Vol. 44, No. 2, February pp. 139-143GlobalMicroprobe analysis, Mineral exploration
DS2002-1119
2002
Petersen, F.W.Mutemeri, N., Petersen, F.W.Small scale mining in South Africa: past, present and futureNatural Resources Forum, Vol. 26, 4, pp. 286-92.South AfricaEconomics
DS201412-0681
2014
Petersen, K.Petersen, K.Minerals processing at Rockwell.GSSA Kimberley Diamond Symposium and Trade Show provisional programme, Sept. 10-12, POSTERTechnologyMetallugy
DS201609-1709
2010
Petersen, K.Campbell, J.A.H., Lamb, W., Clarke, J., Petersen, K.The development of AK6.The 4th Colloquium on Diamonds - source to use held Gabarone March 1-3, 2010, 20p.Africa, BotswanaDeposit - AK6
DS201602-0235
2015
Petersen, K.D.Schiffer, C., Stephenson, R.A., Petersen, K.D., Nielsen, S.B., Jacobsen, B.H., Balling, N., Macdonald, D.I.M.A sub crustal piercing point for North Atlantic reconstructions and tectonic implications.Geology, Vol. 43, 12, pp. 1087-1090.Europe, GreenlandPlate Tectonics

Abstract: Plate tectonic reconstructions are usually constrained by the correlation of lineaments of surface geology and crustal structures. This procedure is, however, largely dependent on and complicated by assumptions on crustal structure and thinning and the identification of the continent-ocean transition. We identify two geophysically and geometrically similar upper mantle structures in the North Atlantic and suggest that these represent remnants of the same Caledonian collision event. The identification of this structural lineament provides a sub-crustal piercing point and hence a novel opportunity to tie plate tectonic reconstructions. Further, this structure coincides with the location of some major tectonic events of the North Atlantic post-orogenic evolution such as the occurrence of the Iceland Melt Anomaly and the separation of the Jan Mayen microcontinent. We suggest that this inherited orogenic structure played a major role in the control of North Atlantic tectonic processes.
DS1993-1224
1993
Petersen, N.Petersen, N., Vinnik, L., Kosarev, G., Kind, R., Oreshin, S., Stummler, K.Sharpness of the mantle discontinuitiesGeophysical Research Letters, Vol. 20, No. 9, May 7, pp. 859-862.MantleGeophysics
DS1994-1367
1994
Petersen, O.V.Petersen, O.V., et al.Leifite from the Ilmaussaq alkaline complex, South GreenlandNeues Jahrbuch f?r Mineralogie, 1994, No. 2, pp. 83-90.GreenlandAlkaline rocks, Ilmaussaq Complex
DS2001-0910
2001
Petersen, O.V.Petersen, O.V., Gault, R.A., Balic-Zunic, T.Odintsovite from the Ilimaussaq alkaline complex, South GreenlandNeues Jahrbuch f?r Mineralogie Mh., No. 5, pp. 235-40.GreenlandAlkaline rocks, Ilmaussaq Complex
DS2002-1252
2002
Petersen, O.V.Petersen, O.V., Giester, G., Brandstatter, NiedermayrNabesite, new mineral species from Ilmaussaq alkaline complex, south GreenlandCanadian Mineralogist, Vol.40,1,Feb.pp. 173-81.GreenlandAlkaline rocks
DS2002-1253
2002
Petersen, O.V.Petersen, O.V., Niedermayr, G., Johnson, O., Gault, R.Lovdarite from the Ilmaussaq alkaline complex, South GreenlandNeues Jahrbuch Mineralogy Monatsche, Vol.14, 1, pp. 23-30.GreenlandAlkaline - mineralogy
DS200412-1535
2004
Petersen, O.V.Petersen, O.V., Johnsen, O., Gault, R.A., Niedermayr, G., Grice, J.D.Taseqite, a new member of the eudialyte group from the Ilmassaq alkaline complex.Neues Jahrbuch fur Mineralogie - Monatshefte, No. 2, Feb. 1, pp. 83-96.Europe, GreenlandMineralogy
DS201704-0628
2017
Petersen, S.Hannington, M., Petersen, S., Kratschell, A.Subsea mining moves closer to shore.Nature Geoscience, Vol. 10, 3, pp. 158-159.TechnologyMining - seabed

Abstract: Mining the deep seabed is fraught with challenges. Untapped mineral potential under the shallow, more accessible continental shelf could add a new dimension to offshore mining and help meet future mineral demand.
DS1984-0583
1984
Petersen, T.A.Petersen, T.A., Brown, L.D., Cook, F.A., Kaufman, S., Oliver, J.Structure of the Riddleville Basin from Cocorp Seismic Data and Implications for Reactivation Tectonics.Journal of GEOLOGY, Vol. 92, PP. 261-271.GlobalMid-continent
DS1975-1182
1979
Petersen, U.Petersen, U.Metallogenesis of South AmericaEpisodes, FOR 1979 No. 4, PP. 3-11.South AmericaGeology, Diamonds
DS1982-0495
1982
Petersen, U.Petersen, U.Metalogenesis in South America: Progress and ProblemsI.u.g.s. Publn. Metalogenesis En Latinoamerica., No. 5, PP. 249-274.South America, BrazilRelated Rocks
DS1994-0631
1994
Petersen, U.Gocht, W., Petersen, U.Minerals and the Common Fund for CommoditiesNatural Resources forum, Vol. 18, No. 2, May pp. 143-151AfricaEconomics, Common fund for commodities
DS1995-0815
1995
Petersen, U.Holland, H.D., Petersen, U.Living dangerously... earth, resources and environmentPrinceton University of Press, 600p. approx. $ 60.00GlobalBook -ad, Earth resources
DS2000-0384
2000
PetersonHanmer, S., Aspler, L., Sandeman, Davis, Peterson, RelfHenik - Kaminak - Tavani supracrustal belt. late Archean oceanic crust and island arc remnants....Geological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) 2000 Conference, 4p. abstract.Northwest Territories, ChurchillProterozoic reworking, Structure
DS2000-0853
2000
PetersonSandeman, H., Cousens, B., Peterson, Hemmingway, davisPetrochemistry and neodymium isotopic evolution of Proterozoic mafic rocks of Western Churchill Province... mantleGeological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) 2000, 4p. abstract.Northwest TerritoriesPetrology, dykes, Kaminak, MacQuid, Tulemalu
DS1988-0542
1988
Peterson, C.D.Peterson, C.D., Binney, S.E.Compositional variations of coastal placers in the PacificNorthwest, USAMarine Mining, Vol. 7, No. 4, pp. 397-416CordilleraPlacers- Coastal
DS1989-1202
1989
Peterson, F.Peterson, F., Turner-Peterson, C.Geology of the Colorado PlateauAmerican Geophysical Union (AGU) 28th. International Geological Congress Field Trip Guidebook, No. T 130, 65pColorado PlateauRegional geology
DS1984-0584
1984
Peterson, I.Peterson, I.Old Time Diamonds - Dating in the RoughScience News, Vol. 126, No. 4, JULY 28TH. PP. 54-55.GlobalGeochronology
DS1984-0585
1984
Peterson, I.Peterson, I.Liquid Carbon- the Melting of a DiamondSci. News, Vol. 126, No. 11, SEPT. 15TH. P. 164.GlobalMineral Chemistry
DS2001-0911
2001
Peterson, J.Peterson, J., Todd, J.Wall control blasting practices at the Ekati diamond mineThe Canadian Mining and Metallurgical Bulletin (CIM Bulletin) ., Vol. 94, No. 1050, May pp. 67-73.Northwest TerritoriesMining, blasting, Deposit - Ekati
DS1997-0805
1997
Peterson, L.N.Mkrtychan, G.A., Peterson, L.N.Lithologo facies types of diamond and pyrope bearing carbon reservoirs In the Tychany Diamondiferous region.Russian Geology and Geophysics, Vol. 38, No. 4, pp. 818-824.RussiaDiamond morphology, Garnet
DS201112-0785
2010
Peterson, N.Peterson, N.Carbonated mantle lithosphere in the western Canadian Cordillera.Thesis: University of British Columbia Msc., Canada, British ColumbiaThesis - note availability based on request to author
DS1998-0067
1998
Peterson, R.Bailey, L.M., Helmstaedt, H.H., Peterson, R., MandarinoMicrodiamonds and indicator minerals from a talc schist rock, FrenchGuiana.7th International Kimberlite Conference Abstract, pp. 37-39.GlobalMetakimberlites, Paramaca series
DS1989-1294
1989
Peterson, R.C.Roelofsen-Ahl, J.N., Peterson, R.C.Gittinsite: a modification of the Thortveitite structureCanadian Mineralogist, Vol. 27, No. 4, December pp. 703-708QuebecStrange Lake, Alkaline Complex
DS2000-0407
2000
Peterson, R.C.Herd, C.D.K., Peterson, R.C.Violet coloured diopside from southern Baffin Island, Nunavut CanadaCanadian Mineralogist, Vol. 38, pt. 5, Oct. pp. 1193-99.Northwest Territories, Nunavut, Baffin IslandMineral chemistry - not specific to diamonds
DS1975-0160
1975
Peterson, R.M.Peterson, R.M.Interpretation of Aeromagnetic Patterns and Basement Structure from Erts Imagery.Geological Society of America (GSA), Vol. 7, No. 2, PP. 225-226. (abstract.).GlobalMid-continent
DS1985-0525
1985
Peterson, R.M.Peterson, R.M.Mapping Paleostructures from Time Related Aeromagnetic Lineaments and Photolineaments.Geological Society of America (GSA), Vol. 17, No. 7, P. 687. (abstract.).United States, Appalachia, KentuckyGeotectonics
DS1992-0875
1992
Peterson, S.D.Klein, B.W., Graham, A.P., Peterson, S.D.Mining in 1992: a cautious optimism. (United States)Minerals Today, February pp. 6-11United StatesMining, Economics
DS1991-0092
1991
Peterson, T.Bell, K.R., Peterson, T.neodymium and Strontium isotope systematics of Shombole volcano, East-Africa, and the links between nephelinites, phonolites and carbonatitesGeology, Vol. 19, No. 6, June pp. 582-585TanzaniaGeochronology, Carbonatite
DS1991-0882
1991
Peterson, T.Kjarsgaard, B., Peterson, T.Nephelinite-carbonatite liquid immisibility at Shombole volcano, East-Africa-petrographic and experimental evidenceMineral. Petrology, Vol. 43, No. 4, May pp. 293-314East Africa, TanzaniaCabonatite, Experimental petrology
DS1991-1338
1991
Peterson, T.Peterson, T.Tectonics and genesis of 1.85 Ga ultrapotassic volcanism, District ofKeewatinGeological Association of Canada (GAC)/Mineralogical Association of Canada (MAC)/SEG Annual Meeting May 27-29. Toronto, Ontario, Abstract, Vol. 16, p. A98. AbstractNorthwest TerritoriesTectonics, Ultrapotassic alkaline rocks
DS1992-1189
1992
Peterson, T.Peterson, T.Geology map of the Dubawnt Lake area, Northwest TerritoriesGeological Survey of Canada, Open File, No. 2551, 1 map 1:100, 000 $ 15.00Northwest TerritoriesMap, Dubawnt Lake
DS1996-0073
1996
Peterson, T.Baragar, W.R.A., Ernst, R.E., Hulbert, m L., Peterson, T.Longitudinal petrochemical variation in the Mackenzie dyke swarm northwestern Canadian shield.Journal of Petrology, Vol. 37, No. 2, pp. 317-359.Northwest TerritoriesPetrochemistry, Mackenzie dike swarm
DS2003-1055
2003
Peterson, T.Pehrsson, S.J., Peterson, T., Davis, W.J., Sandeman, Skulski, Van BreenenAncient Archean crust in the Western Churchill Province: a review of direct and indirect31st Yellowknife Geoscience Forum, p. 75. (abst.)Saskatchewan, Manitoba, NunavutTectonics - lithosphere
DS2003-1056
2003
Peterson, T.Pehrsson, S.J., Peterson, T., Davis, W.J., Sandeman, Skulski, Van BreenenThe Western Churchill metallogeny project: from Melville to Uranium City, a new look31st Yellowknife Geoscience Forum, p. 77. (abst.)Saskatchewan, Manitoba, Nunavut, Northwest TerritoriesBedrock compilation
DS200412-1515
2003
Peterson, T.Pehrsson, S.J., Peterson, T., Davis, W.J., Sandeman, Skulski, Van Breenen, Hartlaub, Wodicks, Hanmer, CousensAncient Archean crust in the Western Churchill Province: a review of direct and indirect evidence.31st Yellowknife Geoscience Forum, p. 75. (abst.)Canada, Saskatchewan, Manitoba, NunavutTectonics - lithosphere
DS200412-1516
2003
Peterson, T.Pehrsson, S.J., Peterson, T., Davis, W.J., Sandeman, Skulski, Van Breenen, Hartlaub, Wodicks, Hanmer, CousensThe Western Churchill metallogeny project: from Melville to Uranium City, a new look at the largest under explored Craton in the31st Yellowknife Geoscience Forum, p. 77. (abst.)Canada, Saskatchewan, Manitoba, Northwest Territories, NunavutBedrock compilation
DS202103-0402
2021
Peterson, T.Regis, D., Pehrsson, S., Martel, E., Thiessen, E., Peterson, T., Kellett, D.Post - 1.9 Ga evolution of the south Rae craton ( Northwest Territories), Canada: a paleoproterozoic orogenic collapse system.Precambrian Research, Vol. 355, 106105, 29p. PdfCanada, Northwest Territoriessunduction

Abstract: The Trans-Hudson Orogen (THO), formed from the convergence between the Superior craton and the composite Churchill Upper Plate (CUP), is one of the best-preserved examples of a collisional orogen in the Paleoproterozoic. Similar to modern collision systems such as the Himalayan orogen, it is characterized by a composite upper plate in which terrane accretion established a continental plateau that was tectonically and magmatically active for >100 myr. Our study presents new petrological and geochronological data for four samples collected in three lithotectonic domains of the south Rae craton (one of the CUP terranes). The results presented here allow us to re-define the previously proposed extent of THO reworking in the CUP and afford the opportunity to study and compare the evolution of various fragments that illustrate differing levels of a collapsed plateau in the CUP hinterland. The new data indicate that the south Rae craton locally preserves evidence for burial at 1.855-1.84 Ga with peak metamorphic conditions at approximately 790 °C and 9.5-12.5 kbar followed by rapid cooling and decompression melting (P < 6 kbar) at ca. 1.835-1.826 Ga. These results, which provide important and so far missing Pressure-Temperature-time (P-T-t) constraints on the evolution of the south Rae craton in the Northwest Territories at Trans-Hudson time, coupled with existing regional geochronological and geochemical data, are used to propose an updated model for the post-1.9 Ga THO collision and extensional collapse. Our results reveal that: i) initial thickening in the upper plate started at Snowbird time (ca. 1.94 Ga), then continued via Sask collision (with high-grade metamorphism recorded in the south Rae craton, ca. 1.85 Ga), and ended with Superior collision (ca. 1.83 Ga); ii) the extent of the THO structural and metamorphic overprint in the SW CUP is much broader across strike than previously recognized, and iii) T-t data in the south Rae are indicative of relatively fast cooling rates (8-25 °C/Ma) compared to other known Precambrian orogens. We suggest that the Paleoproterozoic THO represents the first record of a major ‘modern-style’ orogenic plateau collapse in Earth’s history.
DS1986-0640
1986
Peterson, T.D.Peterson, T.D.Sodium metasomatism and mineral stabilities in alkaline ultra-maficrocks: implications for the origin of the sodic lavas of Oldoinyo l'EngaiEos, Vol. 67, No. 16, April 22, p. 389. (abstract.)Democratic Republic of CongoBlank
DS1987-0579
1987
Peterson, T.D.Peterson, T.D.The petrogenesis and evolution of nephelinite-carbonatite magmasPh.D. Thesis, John Hopkins Univ, 406pTanzaniaBlank
DS1989-1203
1989
Peterson, T.D.Peterson, T.D.A microprobe study of natrocarbonatite #1Geological Association of Canada (GAC) Annual Meeting Program Abstracts, Vol. 14, p. A81. (abstract.)KenyaOldoinyo L'engai, Carbonatite
DS1989-1204
1989
Peterson, T.D.Peterson, T.D.The nature and origin of primary carbonatite magmasGeological Association of Canada (GAC) Annual Meeting Program Abstracts, Vol. 14, p. A51. (abstract.)TanzaniaNephelinite-carbonatite, Carbonatite
DS1989-1205
1989
Peterson, T.D.Peterson, T.D.A microprobe study of natrocarbonatite #3Eos, Vol. 70, No. 15, April 11, p. 491. (abstract.)TanzaniaOldoinyo L'engai, Carbonatite
DS1989-1206
1989
Peterson, T.D.Peterson, T.D.Peralkaline nephelinites. I. Comparative petrology of Shombole and Oldoinyo l'engai,East AfricaContributions to Mineralogy and Petrology, Vol. 101, No. 4, pp. 458-478Tanzania, East AfricaNephelinite, Oldoinyo L'engai
DS1989-1207
1989
Peterson, T.D.Peterson, T.D., Carmichael, I.S.E.A microprobe study of natrocarbonatite #2Eos, Vol. 70, No. 15, April 11, p. 491. (abstract.)Democratic Republic of CongoOldoinyo L'engai, Carbonatite
DS1990-1176
1990
Peterson, T.D.Peterson, T.D.Petrology and genesis of natrocarbonatiteContributions to Mineralogy and Petrology, Vol. 105, No. 2, pp. 143-155GlobalCarbonatite -natrocarbonatite, Petrology
DS1990-1177
1990
Peterson, T.D.Peterson, T.D.Regional lamproite-minette volcanism in the ThelonHinterland: volcanic successions and tectonics In the Dubawnt Lake area, N.W.T.G.s.c. Forum January 16-17, Ottawa, Poster display AbstractNorthwest TerritoriesLamproite, Minette
DS1990-1178
1990
Peterson, T.D.Peterson, T.D., Rainbird, R.H.Tectonic and petrological significance of regional lamproite-minette volcanism in the The lon and Trans-Hudson hinterlands, Northwest TerritoriesGeol. Suv. of Canada Current Research Part C., Canadian Shield, Paper No. 90-1C, pp. 69-80Northwest TerritoriesLamproite-minette, Tectonics/petrology
DS1991-0883
1991
Peterson, T.D.Kjarsgaard, B., Peterson, T.D.Kimberlites of Somerset Island, District of Franklin, NorthwestTerritoriesGeological Survey of Canada Forum held January 21-23, 1990 in Ottawa, p. 11 AbstractNorthwest TerritoriesSampling -rock types for Geological Society of Canada (GSC) collection, Kimberlites
DS1992-0873
1992
Peterson, T.D.Kjarsgaard, B.A., Peterson, T.D.Kimberlite-derived ultramafic xenoliths from the diamond stability field: A new Cretaceous geotherm for Somerset Island, Northwest TerritoriesGeological Survey of Canada, No. 92-1B, pp. 1-6Northwest TerritoriesXenoliths, GeotherM.
DS1992-1190
1992
Peterson, T.D.Peterson, T.D.Early Proterozoic ultrapotassic volcanism of the Keewatin Hinterland, Central Canada #1Eos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p.335Northwest Territories, Saskatchewan, United StatesChurchill Province, Wyoming Province, Alkaline rocks
DS1993-1225
1993
Peterson, T.D.Peterson, T.D.Magnesiochromite in lamproitic rocks, District of Keewatin, Northwest TerritoriesGeological Society of Canada (GSC) Forum abstracts, p. 16 poster abstract.Northwest TerritoriesLamproitic rocks, Geochemistry
DS1993-1226
1993
Peterson, T.D.Peterson, T.D.Lamproites and diamond potential of the Churchill ProvinceThe Canadian Mining and Metallurgical Bulletin (CIM Bulletin) , Annual Meeting Abstracts approximately 10 lines, Vol. 86, No. 968, March ABSTRACT p. 71.Northwest Territories, AlbertaDikes, Archean
DS1993-1227
1993
Peterson, T.D.Peterson, T.D.Lamproites and the diamond potential of the Churchill ProvinceThe Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Annual Meeting Preprint, Paper No. 100, 18p.Northwest Territories, AlbertaLamproites, Overview of area
DS1993-1228
1993
Peterson, T.D.Peterson, T.D., Spratt, D.A.Analcite bearing igneous rocks from the Crowsnest Formation, southwesternAlberta.Geological Survey Canada Paper, No. 93-1C, pp. 51-57.AlbertaIgneous rocks
DS1994-0921
1994
Peterson, T.D.Kjarsgaard, B.A., Hamilton, D.L., Peterson, T.D.Peralkaline nephelinite carbonatite liquid immiscibility: comparison of phase compositions..lavasCarbonatite volcanism, Ed. Bell, K., Keller, J., pp. 163-190.TanzaniaPetrology - Carbonatite volcanism., Deposit -Oldoinyo Lengai
DS1994-1368
1994
Peterson, T.D.Peterson, T.D.Early Proterozoic ultrapotassic volcanism of the Keewatin hinterland, Canada. #2Proceedings of Fifth International Kimberlite Conference, Vol. 1, pp. 221-235.Northwest TerritoriesAlkaline rocks, Ultrapotassic volcanics
DS1994-1369
1994
Peterson, T.D.Peterson, T.D., Currie, K.L.The Ice River Complex, British ColumbiaGeological Survey of Canada Current Research, 1994-A, pp. 185-192.British ColumbiaAlkaline rocks, Ijolite, carbonatite
DS1994-1370
1994
Peterson, T.D.Peterson, T.D., Kjarsgaard, B.A.What are the parental magmas at Oldoinyo Lengai?Carbonatite volcanism, Ed. Bell, K., Keller, J., pp. 148-162.TanzaniaPetrology - Carbonatite volcanism., Deposit -Oldoinyo Lengai
DS1995-0811
1995
Peterson, T.D.Hogarth, D.D., Peterson, T.D.Leucite bearing dykes of southeast Baffin Island: a new lamproite locality.Geological Association of Canada (GAC) Annual Meeting Abstracts, Vol.Northwest Territories, Baffin IslandLamproite
DS1995-0812
1995
Peterson, T.D.Hogarth, D.D., Peterson, T.D.Leucite bearing dykes of southeast Baffin Island: a new lamproite localityGeological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) Annual Meeting Abstracts, Vol. 20, p. A45 AbstractNorthwest Territories, Baffin IslandLamproites
DS1995-1488
1995
Peterson, T.D.Peterson, T.D.Early Proterozoic ultrapotassic volcanism of the Keewatin Hinterland, Canada. #3Preprint, 15p.Northwest TerritoriesBaker Lake Group, Ultrapotassic
DS1995-1489
1995
Peterson, T.D.Peterson, T.D.A potassic phreatomagmatic volcanic centre in the The lon basin:implications for diamond exploration.Geological Survey of Canada, Paper 1995-C, pp. 19-26.Northwest TerritoriesLamproites
DS1995-1490
1995
Peterson, T.D.Peterson, T.D., Esperanca, S., LeCheminant, A.N.Geochemistry and origin of the Proterozoic ultrapotassic rocks of the Churchill Province, Canada.Mineralogy and Petrology, Vol. 51, No. 2/4, pp. 251-276.Northwest TerritoriesAlkaline rocks, Deposit -Churchill Province
DS1996-0641
1996
Peterson, T.D.Hogarth, D.D., Peterson, T.D.Lamproite dykes of southeast Baffin IslandGeological Survey of Canada, LeCheminant ed, OF 3228, pp. 109-100.Northwest Territories, Baffin IslandLamproite, Dykes
DS1996-1112
1996
Peterson, T.D.Peterson, T.D.Lamproites - GSCGeological Survey of Canada, LeCheminant ed, OF 3228, pp. 79-86.CanadaGeology, Technology
DS1996-1113
1996
Peterson, T.D.Peterson, T.D., LeCheminant, A.N.Ultrapotassic rocks of the Dubawnt Supergroup, District of Keewatin, northwest TerritoriesGeological Survey of Canada, LeCheminant ed, OF 3228, pp. 97-100.Northwest TerritoriesAlkaline rocks -ultrapotassic, Christopher Island Formation
DS2001-0912
2001
Peterson, T.D.Peterson, T.D., Van Breemen, Sandeman, CousensPostorogenic granitoids and ultrapotassic rocks in the Hinterland of the Trans Hudson Orogen.Geological Association of Canada (GAC) Annual Meeting Abstracts, Vol. 26, p. 117.abstract.Saskatchewan, GreenlandMinettes
DS2002-1229
2002
Peterson, T.D.Paul, D., Hamner, S., Tella, S., Peterson, T.D., Le Cheminant, A.N.Compilation bedrock geology of part of Western Churchill Province, Nunuvut-Northwest Territories.Geological Survey of Canada Open File, No. 4236, Map 1: 1,000,000 $19.50Northwest Territories, NunavutGeology - not specific to diamonds
DS2002-1254
2002
Peterson, T.D.Peterson, T.D., Van Breemen, O., Sandeman, H., Cousens, B.Proterozoic (1.85-1.75 Ga) igneous suites of the Western Churchill Province: granitoidPrecambrian Research, Vol. 119, No. 1-4, pp. 73-100.Alberta, Northwest TerritoriesMagmatism - tectonics, Minettes, Trans Hudson
DS2002-1255
2002
Peterson, T.D.Peterson, T.D., Von Breemen, O.Postorogenic granitoids and ultrapotassic rocks in the hinterland of the Trans Hudson Orogen.Gac/mac Annual Meeting, Saskatoon, Abstract Volume, P.91., p.91.Saskatchewan, ManitobaOrogen, Minette dyke swarm
DS2002-1256
2002
Peterson, T.D.Peterson, T.D., Von Breemen, O.Postorogenic granitoids and ultrapotassic rocks in the hinterland of the Trans Hudson Orogen.Gac/mac Annual Meeting, Saskatoon, Abstract Volume, P.91., p.91.Saskatchewan, ManitobaOrogen, Minette dyke swarm
DS200412-0782
2004
Peterson, T.D.Hanmer, S., Sandeman, H.A., Davis, W.J., Aspler, L.B., Rainbird, R.H., Ryan, J.J., Relf, C., Peterson, T.D.Geology and Neoarchean tectonic setting of the Central Hearne supracrustal belt, Western Churchill Province, Nunavut, Canada.Precambrian Research, Vol. 134, 1-2, pp. 63-83.Canada, NunavutTectonics - not specific to diamonds
DS200412-1609
2003
Peterson, T.D.Rainbird, R.H., Hadlari, T., Aspler, L.B., Donaldson, J.A., Le Cheminant, A.N., Peterson, T.D.Sequence stratigraphy and evolution of the Paleoproterozoic intracontinental Baker Lake and The lon Basins, western Churchill ProPrecambrian Research, Vol. 125, 1-2, pp. 21-53.Canada, NunavutGeology
DS200412-1727
2004
Peterson, T.D.Sandeman, H.A., Hanmer, S., Davis, W.J., Ryan, J.J., Peterson, T.D.Neoarchean volcanic rocks, central Hearne supracrustal belt, Western Churchill Province: geochemical and isotopic evidence suppoPrecambrian Research, Vol. 134, no. 1-2, Sept. 20, pp. 113-141.Canada, Nunavut, Northwest TerritoriesSubduction
DS200612-1419
2005
Peterson, T.D.Tella, S., Paul, D., Davis, W.J., Berman, R.G., Sandeman, H.A., Peterson, T.D., Pehrsson, KerswillBedrock geology compilation and regional synthesis, parts of Hearne domain, Nunavut.Geological Survey of Canada Open file, No. 4729, 2 sheetsCanada, NunavutMap - geology - mentions diamonds
DS201112-0786
2011
Peterson, T.D.Peterson, T.D., Scott, J.M.J., Jefferson, C.W.Uranium rich bostonite carbonatite dykes in Nunavut: recent observations. Deep Rose Lake area - minetteGeological Survey of Canada, Current Research 2011-11, 12p.Canada, NunavutCarbonatite
DS1996-1114
1996
Petersons, H.F.Petersons, H.F., Constable, S.Global mapping of the electrically conductive lower mantleGeophysical Research Letters, Vol. 23, No. 12, June 1, pp. 1461-64.MantleGeophysics -magnetics, Mapping lower mantle
DS200612-0957
2006
Petesen, F.W.Mutemeri, N., Petesen, F.W.Small scale mining in South Africa: past present and future.Natural Resources Forum, Vol. 26. 4, pp. 286-292.Africa, South AfricaMining - artisanal, alluvial
DS1992-1465
1992
Petesen, N.Stammler, K., Kind, R., Petesen, N., Kosarev, G., Vinnik, L., LiuThe upper mantle discontinuities: correlated or anticorrelated?Geophysical Research Letters, Vol. 19, No. 15, August 3, pp. 1563-1566MantleDiscontinuity, Structure
DS1993-0047
1993
Petford, N.Atherton, M.P., Petford, N.Generation of sodium rich magmas from newly underplated basaltic crustNature, Vol. 362, March 11, pp. 144-146PeruCrust, Trondjhemite
DS1993-0048
1993
Petford, N.Atherton, M.P., Petford, N.Generation of sodium-rich magmas from newly underplated basaltic crustNature, Vol. 362, March 11, pp. 144-146PeruSubduction, Crust
DS1993-1229
1993
Petford, N.Petford, N., Kerr, R.C., Lister, J.R.Dike transport of granitoid magmasGeology, Vol. 21, No. 9, September pp. 845-848Andes, PeruGranites, Dike-flow ascent
DS1994-1371
1994
Petford, N.Petford, N., Lister, J.R., Kerr, R.C.The ascent of felsic magmas in dykesLithos, Vol. 32, No. 1-2, March pp. 161-168GlobalMagma, Dikes
DS1995-1491
1995
Petford, N.Petford, N.Segregation of tonalitic -trondhjemitic melts in the continental crust: The mantle connectionJournal of Geophysical Research, Vol. 100, No. B8, Aug. 10, pp. 15, 735-744MantleCrust, Trondhjemite
DS1995-1492
1995
Petford, N.Petford, N., Atherton, M.P.Cretaceous -Tertiary volcanism and syn-subduction crustal extension In northern central Peruvolcanism associated with extension consuming plate ., pp. 233-248PeruTectonics
DS1996-1115
1996
Petford, N.Petford, N., Atherton, M.Sodium rich partial melts from newly underplated basaltic crust, the Cordillera Blanca batholith, PeruJournal of Petrology, Vol. 37, No. 6, Dec. pp. 1491-1521PeruBasalts, Cordillera Blanca batholith area
DS2001-0913
2001
Petford, N.Petford, N., Gallagher, K.Partial melting of mafic amphibilitic lower crust by periodic influx of basaltic magmaEarth and Planetary Science Letters, Vol. 193, No. 3-4, pp.483-99.MantleMagmatism
DS2003-1274
2003
Petford, N.Simakin, A.G., Petford, N.Melt distribution during the bending of a porous, partially melted layerGeophysical Research Letters, Vol. 30, 11, 10.1029/2003GLO16949MantleMelting
DS200412-1825
2003
Petford, N.Simakin, A.G., Petford, N.Melt distribution during the bending of a porous, partially melted layer.Geophysical Research Letters, Vol. 30, 11, 10.1029/2003 GLO16949MantleMelting
DS200512-0114
2005
Petford, N.Brietkreuz, C., Petford, N.Physical geology of high level magmatic systems.Geological Society of London, SP 234, 262p.Mantle, Europe, PolandBook - magmatism, laccoliths, sills
DS200512-0849
2005
Petford, N.Petford, N., Yuen, D., Rushmer, T.,Brodholt, J., Stackhouse, S.Shear induced material transfer across the core mantle boundary aided by the post perovskite phase transition.Earth Planets and Space, Vol. 57, 5, pp. 459-464.MantleMineralogy
DS201112-0482
2011
Petford, N.Jerram, D., Petford, N.The field description of igneous rocks, second edition.Wiley Blackwell, 256p. $ 40.00TechnologyBook - field guide
DS201512-1955
2015
Petherbridge, W.Novy, L., Petherbridge, W.Ekati Long Lake containment facility reclamation research.43rd Annual Yellowknife Geoscience Forum Abstracts, abstract p. 76.Canada, Northwest TerritoriesDeposit - Ekati

Abstract: The Ekati Diamond Mine is a surface and underground diamond mine operated by Dominion Diamond Ekati Corporation. It is located near the Lac de Gras Northwest Territories, Canada approximately 300 km north of Yellowknife and roughly 200 km south of the Arctic Circle. The Ekati Long Lake Containment Facility (LLCF) is a five celled containment area for storage of processed kimberlite generated during the processing and extraction of diamonds from kimberlite ore. The LLCF has been in operation since 1998 and deposition of processed kimberlite has occurred within the three northern cells with the remaining two cells being used for water quality “polishing” to help meet discharge criteria. The Interim Closure and Reclamation Plan for Ekati outlines a plan to cover the LLCF kimberlite surface with a combination of rock and vegetation. The cover system looks to fulfill the closure objective of physically stabilizing the processed kimberlite and creating a landscape safe for wildlife and human use. Cell B of the LLCF has reached its capacity and is being used as a reclamation research area. The purpose of the reclamation research is to identify a long term cover design that can be expanded to the whole LLCF. A winter drilling investigation in Cell B of the LLCF was undertaken in 2013. The objective of the investigation was to characterize the processed kimberlite and its porewater chemistry. Results from the investigation indicated that permafrost has aggraded into the kimberlite and surface zone pore water concentrations were higher when compared to process plant discharge. In fall of 2013 various areas of Cell B were seeded with annual and perennial vegetation ground covers. Further seeding of Cell B was completed in the summer of 2014. Seed from a variety of sources that includes locally harvested and commercially available native plants and farm crops was applied at different rates using different seeding techniques. In the winter of 2013 rock was placed in various configurations within the seeded areas to evaluate its effects on vegetation growth and erosion control. A total of 25 hectares has been seeded in Cell B since the fall of 2013 and the results of initial monitoring are positive regarding establishment of long term ground cover on the kimberlite.
DS201912-2831
2019
Petherbridge, W.Trefry, K., Petherbridge, W.Ekati Long Lake containment facility ( LLCF) reclamation research.Yellowknife Forum NWTgeoscience.ca, abstract volume p. 95-96.Canada, Northwest Territoriesdeposit - Ekati

Abstract: The Ekati Diamond Mine is a surface and underground diamond mine operated by Dominion Diamond Mines. It is located near Lac de Gras within the Northwest Territories, Canada approximately 300 km north of Yellowknife and roughly 200 km south of the Arctic Circle. The Long Lake Containment Facility (LLCF) is the primary containment area for processed kimberlite (PK) storage after the extraction of diamonds from kimberlite ore. The facility has been in operation since 1998 and is the main repository of PK from open pit and underground mines at the Ekati Mine. The overall reclamation goal for the LLCF is the design and construction of a long-term cover that will physically stabilize the PK, with a landscape that will be safe for human and wildlife use. The proposed final closure design for the LLCF includes the following components: 1) Combination of vegetation and rock cover system to physically stabilize the PK. Vegetation is planned to be the main stabilization component of the PK. Rock placement is intended to promote a localized environment for vegetation growth and provide larger-scale wind and water erosion protection. 2) Water drainage channels to convey surface water flow through the containment cells and into settling ponds. Since 2012, reclamation research has been ongoing at Cell B of the LLCF with the overall intent of addressing uncertainties with the proposed final LLCF cover design. Separate reclamation research programs focused on addressing the uncertainties of vegetation growth in PK are being carried out under this project. Dominion’s short-term research goal has been to establish and evaluate the vegetation growth directly within PK. Main components of the LLCF reclamation research includes evaluation of soil amendments, rock/vegetation combinations, annual crop cover, plant species trials, mine-generated organic matter application, seed collection/distribution, and natural vegetation colonization. The LLCF reclamation research aims to establish a best practice that could be adapted by other mining operations looking to reclaim PK containment sites. Annual vegetation monitoring and continued program expansion aid in reaching that goal. Recent program undertakings have included: 1)Surface water management research through trial channel construction and further bio-engineering of existing channels 2) Mycorrhizae inoculation to improve soil microbial communities 3) Implementation of rough and loose mounding as an erosion control measure 4) Evaluation of the feasibility of using organic matter generated from the Ekati composter facility 5) Harvesting of halophytic seed and live plant specimens from saline environments near Kugluktuk, Nunavut for planting in Cell B 6) Utilization of reclamation equipment for earthworks. The LLCF reclamation research has been a vessel for developing methods of utilizing PK as an effective growth medium. High sodium concentrations and low organic matter content present challenges, but also provide opportunities for innovative research to improve environmental conditions and lead to a final closure design. Dominion has included Traditional Knowledge, other scientific knowledge, as well as regulatory and community input as a key component of LLCF reclamation research planning and final cover design.
DS1998-1534
1998
PetibonVeksler, I.V., Petibon, Jenner, Dorfman, DingwellTrace element partitioning in immiscible silicate carbonate liquid systems:an initial experimenatal ...Journal of Petrology, Vol. 39, No. 11-12, Nov-Dec. pp. 2095-2104.MantleCarbonatite, Petrology - experimental
DS1997-0904
1997
Petibon, C.M.Petibon, C.M., Jenner, G.A., Jackson, S.E., Kjarsgaard, B.Petrogenesis of Oldoinyo Lengai carbonatites: constraints from trace element partition coefficients.Geological Association of Canada (GAC) Abstracts, TanzaniaCarbonatite, Deposit - Oldoinyo Lengai
DS1998-1155
1998
Petibon, C.M.Petibon, C.M., Jenner, G.A., Kjarsgaard, B.A.The genesis of natrocarbonatites: constraints from experimental petrology and trace element partition....Mineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 1161-2.TanzaniaCarbonatite, Deposit - Oldoinyo Lengai
DS1998-1156
1998
Petibon, C.M.Petibon, C.M., Kjarsgaard, B., Jenner, G., Jackson, S.Liquidus phase relationships of a silicate bearing natro carbonatite from Oldoinyo Lengai at 20, 100 Mpa.Journal of Petrology, Vol. 39, No. 11-12, Nov-Dec. pp. 2137-51.TanzaniaCarbonatite, Deposit - Oldoinyo Lengai
DS2001-0322
2001
Petibon, C.M.Foley, S.F., Petibon, C.M., Jenner, G.A., Kjarsgaard, B.High U Th partitioning by clinopyroxene from alkali silicate and carbonatite metasomatism: an origin for...Terra Nova, Vol. 13, pp. 104-9.TanzaniaNatrocarbonatite, uranium, thorium partitioning
DS2001-0162
2001
PetitCartigny, P., Jendrzewski, N., Pineau, F., Petit, JavoyVolatile (Carbon,Nitrogen,Argon) variability in MORB and respective roles of mantle source heterogenity and degassing: caseEarth and Planetary Science Letters, Vol. 194, No. 1-2, pp. 241-57.Indian RidgeBasaltic glasses - geochemistry, Argon, Carbon, Nitrogen, MORB
DS2003-1072
2003
PetitPetitFrom hotspots to melting potsScience, No. 5625, June 6, p. 1563.MantleMelting
DS200412-1536
2003
PetitPetitFrom hotspots to melting pots.Science, No. 5625, June 6, p. 1563.MantleMelting
DS200912-0341
2009
PetitJones, A.G., Evans, Muller, Hamilton, Miensopust, Garcia, Cole, Ngwisanyi, Hutchins, Stoffel Fourie, Jelsma, Aravanis, Petit, Webb, WasborgArea selection for diamonds using magnetotellurics: examples from southern Africa.Lithos, In press - available 35p.Africa, South Africa, BotswanaGeophysics - magnetotellurics
DS2000-0761
2000
Petit, C.Petit, C., Ebinger, C.Flexure and mechanical behaviour cratonic lithosphere: gravity models of East African and Baikal riftsJournal of Geophysical Research, Vol. 105, No.8, Aug. 10, pp.19151-62.Russia, East Africa, Tanzania, KenyaGeophysics - gravity, Craton
DS201811-2600
2018
Petit, T.Petit, T., Puskar, L.FTIR spectroscopy of nanodiamonds: methods and interpretation.Diamond & Related Materials, Vol. 89, pp. 52-66.Mantlenanodiamonds

Abstract: Fourier transform infrared spectroscopy (FTIR) is highly sensitive to the surface chemistry of nanodiamonds. In this review, we discuss the different FTIR methods available to characterize nanodiamonds and highlight their advantages and limitations. We also summarize the possible assignments of FTIR spectra of nanodiamonds reported in the literature and discuss FTIR spectra of nanodiamonds modified by different surface treatments. Current work of FTIR applied to in situ and operando characterization of nanodiamonds, in particular nanodiamonds exposed to water or characterized during electrochemical and photocatalytic processes, are also discussed. Finally, perspectives regarding possible future FTIR development for nanodiamonds characterization are proposed.
DS201812-2863
2018
Petit, T.Petit, T., Puskar, L.FTIR spectroscopy of nanodiamonds: methods and interpretation.Diamond & Related Materials, Vol. 89, pp. 52-66.Europe, Germanynanodiamonds
DS202202-0209
2022
Petite, B.Petite, B.Vertical Rewind: Dr. Hans Lundberg: The prospecting pioneer. History of H. Lundberg and EM survey … ** not specific to diamonds https://verticalmag.com/features/vertical-rewind-dr-hans-lundberg-the-prospecting-pioneer/, 10p. Photographs and textCanadageophysics - history
DS200412-0146
2003
Petitet, J.P.Beyssac, O., Brunet, F., Petitet, J.P., Goffe, B., Rouzard, J.N.Experimental study of the microtextural and structural deformations of carbonaceous materials under pressure and temperature.European Journal of Mineralogy, Vol. 15, no. 6, Dec. 1, pp. 937-951.TechnologyCarbon - UHP
DS200612-0156
2006
Petitet, J-P.Bourova, E., Richet, P., Petitet, J-P.Coesite ( SiO2) as an extreme case of superheated crystal: an X-ray diffraction study up to 1776 K.Chemical Geology, Vol. 229, 1-3, May 16, pp. 57-63.TechnologyMineralogy - coesite
DS201412-0151
2014
Petitgirard, S.Crepisson, C., Morard, G., Bureau, H., Prouteau, G., Morizet, Y., Petitgirard, S., Sanloup, C.Magmas trapped at the continental lithosphere-asthenosphere boundary.Earth and Planetary Science Letters, Vol. 393, pp. 105-112.MantleBoundary, magmatism
DS201710-2219
2017
Petitgirard, S.Cerantola, V., Bykova, E., Kupenko, I., Merlini, M., Ismailova, L., McCammon, C., Bykov, M., Chumakov, A.I., Petitgirard, S., Kantor, I., Svityk, V., Jacobs, J., Hanfland, M., Mezouar, M., Prescher, C., Ruffer, R., Prakapenka, V.B., Duvbovinsky, L.How iron carbonates help form diamonds.Nature Communications, July 18 #15960Mantlecarbonate inclusions
DS200612-1086
2006
Petitjean, S.Petitjean, S., Rabinowicz, M., Gregoire, M., Chevrot, S.Differences between Archean and Proterozoic lithospheres: assessment of the possible major role of thermal conductivity.Geochemistry, Geophysics, Geosystems: G3, Vol. 7, Q03021 10.1029/2005 GC001053MantleGeothermometry
DS200812-1013
2008
Petke, T.Scambelluri, M., Petke, T., Van Rosemund, H.L.M.Majoritic garnets monitor deep subsduction fluid flow and mantle dynamics.Geology, Vol. 36, 1, pp.MantleGeodynamics
DS201012-0742
2010
Petke, T.Spandler, C., Petke, T., Hermann, J.Experimental and natural constraints on the composition of UHP metamorphic fluids. Keynote paper.Goldschmidt 2010 abstracts, abstractTechnologyReview - UHP
DS1960-0386
1963
Petkof, B.Petkof, B.Gem Stones; Minerals Yearbook: Metals and Minerals, 1963Minerals Yearbook: Metals And Minerals, 1963, Vol. 1, PP. 537-548.United States, Gulf Coast, Arkansas, Pennsylvania, Brazil, Venezuela, BelgiumIndustrial, Review, Imports, Production
DS1960-0487
1964
Petkof, B.Petkof, B.Gem Stones; Minerals Yearbook: Metals and Minerals,1964Minerals Yearbook: Metals And Minerals,1964, Vol. 1, PP. 537-548.United States, Gulf Coast, Arkansas, South Africa, South America, VenezuelaCurrent Review Of Years Activities
DS1960-0588
1965
Petkof, B.Petkof, B.Gem Stones; Minerals Yearbook: Metals and Minerals, 1965Minerals Yearbook: Metals And Minerals, Vol. 1, PP. 507-514.Brazil, Cameroon, Canada, Quebec, India, West Africa, Ivory CoastReview Of Current Activities, Diamond Sorting Equipment
DS200412-1312
2004
Petkovic, P.Milligan, P.R., Petkovic, P., Drummond, B.J.Potential field datasets for the Australian region: their significance in mapping basement architecture.Hillis, R.R., Muller, R.D. Evolution and dynamics of the Australian Plate, Geological Society America Memoir, No. 372, pp. 129-140.AustraliaGeophysics - seismics
DS201909-2071
2019
Peto, M.K.Parai, R., Mukhopadhyay, S., Tucker, J.M., Peto, M.K.The emerging portrait of an ancient, heterogeneous and continuously evolving mantle plume source.Lithos, Vol. 346-347, 16p. PdfMantleplumes

Abstract: Heterogeneity in the lithophile isotopic compositions of ocean island basalts (OIBs) has long been ascribed to the incorporation of recycled materials into the plume source. OIB heterogeneity indicates that plumes do not sample a pristine primordial reservoir, but rather sample an inhomogeneous mixture of primordial and recycled material generated by convective processes over Earth history. Here we present a synthesis of new insights into the characteristics and nature of the plume mantle source. Recent high precision noble gas data demonstrate that the origin of the reservoir supplying noble gases to plumes is fundamentally distinct from that of the mid-ocean ridge basalt (MORB) mantle reservoir: the two reservoirs cannot be related simply by differential degassing or incorporation of recycled atmospheric volatiles. Based on differences observed in the extinct 129I-129Xe system (t1/2 of 15.7?Ma), the mantle source supplying noble gases to plumes differentiated from the MORB source within ~100?Ma of the start of the Solar System, and the two sources have not been homogenized by 4.45?Ga of mantle convection. Thus, the 129I-129Xe data require a plume source that has experienced limited direct mixing with the MORB source mantle. Analysis of mantle source Xe isotopic compositions of plume-influenced samples with primordial He and Ne indicates that the plume source Xe budget is dominated by regassed atmospheric Xe. He and Ne isotopes are not sensitive to regassing due to low overall concentrations of He and Ne in recycled material relative to primordial material. Therefore, plume-influenced samples with primitive He and Ne isotopic compositions do not necessarily reflect sampling of pristine primordial mantle and the lithophile compositions of these samples should not be taken to represent undifferentiated mantle. In addition to recycled atmospheric Xe, the plume mantle source exhibits high ratios of Pu-fission Xe to U-fission Xe. The high proportion of Pu-fission Xe independently confirms a low extent of degassing of the plume source relative to the MORB source. Heavy noble gases illustrate that the mantle reservoir sampled by plumes is fundamentally distinct from the MORB mantle and reflects ongoing degassing of, and incorporation of recycled material into, an ancient (>4.45?Ga) primordial source. If plumes are derived from large low shear-wave velocity provinces (LLSVPs), then these seismically-imaged structures are ancient and long-lived.
DS200812-1047
2007
Peto, MN.Sharygin, V.V., Szabo, C., Kothay, K., Timina, T.Ju., Peto, MN., Torok, K., Vapnik, Y., Kuzmin, D.V.Rhonite in silica undersaturated alkali basalts: inferences on silicate melt inclusions in olivine phenocrysts.Vladykin Volume 2007, pp. 157-182.RussiaPetrology
DS201312-0703
2013
Petra Diamonds LimitedPetra Diamonds LimitedVisit and overview of Finsch mine: presentation.Petra Diamonds Limited, Jan. 30, 47 slides pptAfrica, South AfricaDeposit - Finsch
DS201506-0290
2015
Petra Diamonds LimitedPetra Diamonds LimitedCullinan: The world's most celebrated diamond mine.Petra Diamonds Limited, petradiamonds.com March 20 pptAfrica, South AfricaDeposit - Cullinan - history
DS1985-0526
1985
Petrakakis, K.Petrakakis, K., Dietrich, H.Minsort- a Program for the Processing and Archivation of Microprobe Analyses of Silicate and Oxide Minerals.Neues Jahrbuch f?r Mineralogie, No. 8, AUGUST PP. 379-GlobalComputer Program, Geochemistry
DS201809-2029
2018
Petrelli, M.Gonzalez-Garcia, D., Petrelli, M., Behrens, H., Vetere, F., Fischer, L.A., Morgavi, D., Perugini, D.Diffusive exchange of trace elements between alkaline melts: implications for element fractionation and timescale estimations during magma mixing.Geochimica et Cosmochimica Acta, Vol. 233, pp. 95-114.Europe, Italyshoshonites

Abstract: The diffusive exchange of 30 trace elements (Cs, Rb, Ba, Sr, Co, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ta, V, Cr, Pb, Th, U, Zr, Hf, Sn and Nb) during the interaction of natural mafic and silicic alkaline melts was experimentally studied at conditions relevant to shallow magmatic systems. In detail, a set of 12 diffusion couple experiments have been performed between natural shoshonitic and rhyolitic melts from the Vulcano Island (Aeolian archipelago, Italy) at a temperature of 1200?°C, pressures from 50 to 500?MPa, and water contents ranging from nominally dry to ca. 2 wt.%. Concentration-distance profiles, measured by Laser Ablation ICP-MS, highlight different behaviours, and trace elements were divided into two groups: (1) elements with normal diffusion profiles (13 elements, mainly low field strength and transition elements), and (2) elements showing uphill diffusion (17 elements including Y, Zr, Nb, Pb and rare earth elements, except Eu). For the elements showing normal diffusion profiles, chemical diffusion coefficients were estimated using a concentration-dependent evaluation method, and values are given at four intermediate compositions (SiO2 equal to 58, 62, 66 and 70 wt.%, respectively). A general coupling of diffusion coefficients to silica diffusivity is observed, and variations in systematics are observed between mafic and silicic compositions. Results show that water plays a decisive role on diffusive rates in the studied conditions, producing an enhancement between 0.4 and 0.7 log units per 1 wt.% of added H2O. Particularly notable is the behaviour of the trivalent-only REEs (La to Nd and Gd to Lu), with strong uphill diffusion minima, diminishing from light to heavy REEs. Modelling of REE profiles by a modified effective binary diffusion model indicates that activity gradients induced by the SiO2 concentration contrast are responsible for their development, inducing a transient partitioning of REEs towards the shoshonitic melt. These results indicate that diffusive fractionation of trace elements is possible during magma mixing events, especially in the more silicic melts, and that the presence of water in such events can lead to enhanced chemical diffusive mixing efficiency, affecting also the estimation of mixing to eruption timescales.
DS201812-2856
2019
Petrelli, M.Nazzarini, S., Nestola, F., Zanon, V., Bindi, L., Scricciolo, E., Petrelli, M., Zanatta, M., Mariotto, G., Giuli, G.Discovery of moissanite in a peralkaline syenite from the Azores Islands.Lithos, Vol. 324-325, pp. 68-73.Europe, Portugal, Azoresmoissanite

Abstract: Our discovery of moissanite grains in a peralkaline syenite from the Água de Pau Volcano (São Miguel, Azores Islands, Portugal) represents the first report of this mineral in present day oceanic geodynamic settings. Raman spectroscopy and single-crystal X-ray diffraction show the presence of both the 6H and 4H polytypes with the predominance of the first one. The distribution of trace elements is homogeneous, except for Al and V. Azorean moissanite often hosts rounded inclusions of metallic Si and other not yet identified metallic alloys. A process involving a flushing of CH4-H2 ultra-reducing fluids in the alkaline melts might be considered as a possible mechanism leading to the formation of natural SiC, thus calling for strongly reducing conditions that were locally met in the crust-mantle beneath the São Miguel Island.
DS202004-0529
2020
Petrescu, L.Petrescu, L., Bastow, I.D., Darbyshire, F.A., Gilligan, A., Bodin, T., Menke, W., Levin, V.Three billion years of crustal evolution in eastern Canada: constraints from receiver functions.Journal of Geophysical Research: Solid Earth, in press available, 24p. PdfCanadageophysics - seismics

Abstract: The geological record of SE Canada spans more than 2.5Ga, making it a natural laboratory for the study of crustal formation and evolution over time. We estimate the crustal thickness, Poisson's ratio, a proxy for bulk crustal composition, and shear velocity (Vs) structure from receiver functions at a network of seismograph stations recently deployed across the Archean Superior craton, the Proterozoic Grenville and the Phanerozoic Appalachian provinces. The bulk seismic crustal properties and shear velocity structure reveal a correlation with tectonic provinces of different ages: the post-Archean crust becomes thicker, faster, more heterogenous and more compositionally evolved. This secular variation pattern is consistent with a growing consensus that crustal growth efficiency increased at the end of the Archean. A lack of correlation among elevation, Moho topography, and gravity anomalies within the Proterozoic belt is better explained by buoyant mantle support rather than by compositional variations driven by lower crustal metamorphic reactions. A ubiquitous ?20km thick high-Vs lower-crustal layer is imaged beneath the Proterozoic belt. The strong discontinuity at 20km may represent the signature of extensional collapse of an orogenic plateau, accommodated by lateral crustal flow. Wide anorthosite massifs inferred to fractionate from a mafic mantle source are abundant in Proterozoic geology and are underlain by high Vs lower crust and a gradational Moho. Mafic underplating may have provided a source for these intrusions and could have been an important post-Archean process stimulating mafic crustal growth in a vertical sense.
DS1983-0514
1983
Petri, S.Petri, S.Geologia Do BrasilSao Paulo: Biblioteca De Ciencas Naturais, Vol. 9.BrazilGeology, Kimberley
DS1983-0515
1983
Petri, S.Petri, S., Fulfaro, V.J.Geologia Do BrasilT.a. Quieroz, Editor Ltda. Rua Joaquim Floriano, 733-4, 0453, 631P.BrazilRegional Geology, Kimberley
DS2003-1073
2003
Petrie, B.S.Petrie, B.S., Sheahan, P.A.The Sheahan-MDRU diamond and mantle rock literature service8 Ikc Www.venuewest.com/8ikc/program.htm, Session 8, POSTER abstractGlobalReferences
DS200412-1537
2003
Petrie, B.S.Petrie, B.S., Sheahan, P.A.The Sheahan-MDRU diamond and mantle rock literature service.8 IKC Program, Session 8, POSTER abstractGlobalDiamond exploration References
DS1997-1106
1997
Petrie, J.Stewart, M., Petrie, J.Life cycle assessment as a tool... potential environmental impactsMining Environmental Management, June pp. 10-13South AfricaEnvironment, Management
DS201602-0230
2016
Petrik, I.Petrik, I., Janak, M., Froitzheim, N., Georgiev, N., Yoshida, K., Sasinkova, V., Konecny, P., Milovska, S.Triassic to Early Jurassic (c.200 Ma) UHP metamorphism in the Central Rhodopes: evidence from U-Pb-Th dating of monazite in diamond bearing gneiss from Chelelpare, Bulgaria.Journal of Metamorphic Geology, in press available, 44p.Europe, BulgariaGneiss - diamonds

Abstract: Evidence for ultrahigh-pressure metamorphism (UHPM) in the Rhodope Metamorphic Complex comes from occurrence of diamond in pelitic gneisses, variably overprinted by granulite facies metamorphism, known from several areas of the Rhodopes. However, tectonic setting and timing of UHPM are not interpreted unanimously. Linking age to metamorphic stage is a prerequisite for reconstruction of these processes. Here we use monazite in diamond-bearing gneiss from Chepelare (Bulgaria) to date the diamond-forming UHPM event in the Central Rhodopes. The diamond-bearing gneiss comes from a strongly deformed, lithologically heterogeneous zone (Chepelare Mélange) sandwiched between two migmatized orthogneiss units, known as Arda-I and Arda-II. Diamond, identified by Raman micro-spectroscopy, shows the characteristic band mostly centred between 1332 and 1330 cm?1. The microdiamond occurs as single grains or polyphase diamond + carbonate inclusions, rarely with CO2. Thermodynamic modelling shows that garnet was stable at UHP conditions of 3.5-4.6 GPa and 700-800 °C, in the stability field of diamond, and was re-equilibrated at granulite facies/partial melting conditions of 0.8-1.2 GPa and 750-800 °C. The texture of monazite shows older central parts and extensive younger domains which formed due to metasomatic replacement in solid residue and/or overgrowth in melt domains. The monazite core compositions, with distinctly lower Y, Th and U contents, suggest its formation in equilibrium with garnet. The U-Th-Pb dating of monazite using electron microprobe analysis yielded a c. 200 Ma age for the older cores with low Th, Y, U and high La/Nd ratio, and a c. 160 Ma age for the dominant younger monazite enriched in Th, Y, U and HREE. The older age of around 200 Ma is interpreted as the timing of UHPM whereas the younger age of around 160 Ma as granulite facies/partial melting overprint. Our results suggest that UHPM occurred in Late Triassic to Early Jurassic time, in the framework of collision and subduction of continental crust after the closure of Palaeotethys.
DS201604-0621
2016
Petrik, I.Petrik, I., Janak, M., Froitzheim, N., Georgiev, N., Yoshida, K., Sasinkova, V., Konecny, P., Milovska, S.Triassic to Early Jurassic ( c. 200Ma) UHP metamorphism in the Central Rhodopes: evidence from U-Pb dating of monazite in diamond bearing gneiss from Chepelare ( Bulgaria).Journal of Metamorphic Geology, Vol. 34, 3, pp. 265-291.Europe, BulgariaUHP diamond bearing gneiss
DS201606-1105
2016
Petrik, I.Petrik, I., Janak, M., Froitzheim, N., Georgiev, N., Yoshida, K., Sasinkova, V., Konecny, P., Milovska, S.Triassic to Early Jurassic ( c. 200Ma) UHP metamorphism in the central Rhodopes: evidence from U-Pb-Th dating of monazite in diamond bearing gneiss from Chepelare Bulgaria.Journal of Metamorphic Geology, Vol. 34, 3, pp. 265-291.Europe, BulgariaDiamonds in gneiss
DS201702-0221
2017
Petrik, I.Klonowska, I., Janak, M., Majka, J., Petrik, I., Froitzheim, N., Gee, D.G., sasinkova, V.Microdiamond on Areskutan confirms regional UHP metamorphism in the Seve Nappe complex of the Scandinavian Caledonides.Journal of Metamorphic Geology, in press availableEurope, Sweden, NorwayUHP

Abstract: Metamorphic diamond in crustal rocks provides important information on the deep subduction of continental crust. Here we present a new occurrence of diamond within the Seve Nappe Complex of the Scandinavian Caledonides, on Åreskutan in Jämtland County, Sweden. Microdiamond is found in-situ as single and composite (diamond + carbonate) inclusions within garnet, in kyanite-bearing paragneisses. The rocks preserve the primary peak pressure assemblage of Ca,Mg-rich garnet + phengite + kyanite + rutile, with polycrystalline quartz surrounded by radial cracks indicating breakdown of coesite. Calculated P-T conditions for this stage are 830-840 °C and 4.1-4.2 GPa, in the diamond stability field. The ultrahigh-pressure (UHP) assemblage has been variably overprinted under granulite facies conditions of 850-860 °C and 1.0-1.1 GPa, leading to formation of Ca,Mg-poor garnet+biotite+ plagioclase+K-feldspar+sillimanite+ilmenite+quartz. This overprint was the result of nearly isothermal decompression, which is corroborated by Ti-in-quartz thermometry. Chemical Th-U-Pb dating of monazite yields ages between 445 and 435 Ma, which are interpreted to record post-UHP exhumation of the diamond-bearing rocks. The new discovery of microdiamond on Åreskutan, together with other evidence of ultrahigh-pressure metamorphism (UHPM) within gneisses, eclogites and peridotites elsewhere in the Seve Nappe Complex, provide compelling arguments for regional (at least 200 km along strike of the unit). UHPM of substantial parts of this far-travelled allochthon. The occurrence of UHPM in both rheologically weak (gneisses) and strong lithologies (eclogites, peridotites) speaks against the presence of large tectonic overpressure during metamorphism.
DS201703-0422
2017
Petrik, I.Klonowska, I., Janak, M., Majka, J., Petrik, I., Froitzheim, N., Gee, D.G., Sasinkova, V.Microdiamond on Areskutan confirms regional UHP metamorphism in the Seve Nappe Complex of the Scandinavian Caledonides.Journal of Metamorphic Geology, in press availableEurope, SwedenMicrodiamond

Abstract: Metamorphic diamond in crustal rocks provides important information on the deep subduction of continental crust. Here, we present a new occurrence of diamond within the Seve Nappe Complex (SNC) of the Scandinavian Caledonides, on Åreskutan in Jämtland County, Sweden. Microdiamond is found in situ as single and composite (diamond+carbonate) inclusions within garnet, in kyanite-bearing paragneisses. The rocks preserve the primary peak pressure assemblage of Ca,Mg-rich garnet+phengite+kyanite+rutile, with polycrystalline quartz surrounded by radial cracks indicating breakdown of coesite. Calculated P-T conditions for this stage are 830-840 °C and 4.1-4.2 GPa, in the diamond stability field. The ultrahigh-pressure (UHP) assemblage has been variably overprinted under granulite facies conditions of 850-860 °C and 1.0-1.1 GPa, leading to formation of Ca,Mg-poor garnet+biotite+plagioclase+K-feldspar+sillimanite+ilmenite+quartz. This overprint was the result of nearly isothermal decompression, which is corroborated by Ti-in-quartz thermometry. Chemical Th-U-Pb dating of monazite yields ages between 445 and 435 Ma, which are interpreted to record post-UHP exhumation of the diamond-bearing rocks. The new discovery of microdiamond on Åreskutan, together with other evidence of ultrahigh-pressure metamorphism (UHPM) within gneisses, eclogites and peridotites elsewhere in the SNC, provide compelling arguments for regional (at least 200 km along strike of the unit) UHPM of substantial parts of this far-travelled allochthon. The occurrence of UHPM in both rheologically weak (gneisses) and strong lithologies (eclogites, peridotites) speaks against the presence of large tectonic overpressure during metamorphism.
DS201707-1340
2017
Petrik, I.Klonowska, I., Janak, M., Majka, J., Petrik, I., Froitzheim, N., Gee, D.Microdiamond on Areskutan confirms UHP metamorphism in the Seve Nappe Complex of the Scandinavian Caledonides.Journal of Metamorphic Geology, Vol. 35, 5, pp. 541-564.Europe, SwedenUHP

Abstract: Metamorphic diamond in crustal rocks provides important information on the deep subduction of continental crust. Here we present a new occurrence of diamond within the Seve Nappe Complex of the Scandinavian Caledonides, on Åreskutan in Jämtland County, Sweden. Microdiamond is found in-situ as single and composite (diamond + carbonate) inclusions within garnet, in kyanite-bearing paragneisses. The rocks preserve the primary peak pressure assemblage of Ca,Mg-rich garnet + phengite + kyanite + rutile, with polycrystalline quartz surrounded by radial cracks indicating breakdown of coesite. Calculated P-T conditions for this stage are 830-840 ºC and 4.1-4.2 GPa, in the diamond stability field. The ultrahigh-pressure (UHP) assemblage has been variably overprinted under granulite facies conditions of 850-860 ºC and 1.0-1.1 GPa, leading to formation of Ca,Mg-poor garnet + biotite + plagioclase + K-feldspar + sillimanite + ilmenite + quartz. This overprint was the result of nearly isothermal decompression, which is corroborated by Ti-in-quartz thermometry. Chemical Th-U-Pb dating of monazite yields ages between 445 and 435 Ma, which are interpreted to record post-UHP exhumation of the diamond-bearing rocks. The new discovery of microdiamond on Åreskutan, together with other evidence of ultrahigh-pressure metamorphism (UHPM) within gneisses, eclogites and peridotites elsewhere in the Seve Nappe Complex, provide compelling arguments for regional (at least 200 km along the unit) UHPM of substantial parts of this far-travelled allochthon. The occurrence of UHPM in both rheologically weak (gneisses) and strong lithologies (eclogites, peridotites) speaks against the presence of large tectonic overpressure during metamorphism.
DS201709-2018
2017
Petrik, I.Klonowska, I., Janek, M., Majka, J., Petrik, I., Froitzheim, N., Gee, D.G., Sasinkova, V.Microdiamond on Areskutan confirms regional UHP metamorphism in the Seve Nappe Complex of the Scandinavian Caledonides.Journal of Metamorphic Geology, Vol. 35, 5, pp. 541-564.Europe, Scandinaviamicrodiamond

Abstract: Metamorphic diamond in crustal rocks provides important information on the deep subduction of continental crust. Here, we present a new occurrence of diamond within the Seve Nappe Complex (SNC) of the Scandinavian Caledonides, on Åreskutan in Jämtland County, Sweden. Microdiamond is found in situ as single and composite (diamond+carbonate) inclusions within garnet, in kyanite-bearing paragneisses. The rocks preserve the primary peak pressure assemblage of Ca,Mg-rich garnet+phengite+kyanite+rutile, with polycrystalline quartz surrounded by radial cracks indicating breakdown of coesite. Calculated P–T conditions for this stage are 830–840 °C and 4.1–4.2 GPa, in the diamond stability field. The ultrahigh-pressure (UHP) assemblage has been variably overprinted under granulite facies conditions of 850–860 °C and 1.0–1.1 GPa, leading to formation of Ca,Mg-poor garnet+biotite+plagioclase+K-feldspar+sillimanite+ilmenite+quartz. This overprint was the result of nearly isothermal decompression, which is corroborated by Ti-in-quartz thermometry. Chemical Th–U–Pb dating of monazite yields ages between 445 and 435 Ma, which are interpreted to record post-UHP exhumation of the diamond-bearing rocks. The new discovery of microdiamond on Åreskutan, together with other evidence of ultrahigh-pressure metamorphism (UHPM) within gneisses, eclogites and peridotites elsewhere in the SNC, provide compelling arguments for regional (at least 200 km along strike of the unit) UHPM of substantial parts of this far-travelled allochthon. The occurrence of UHPM in both rheologically weak (gneisses) and strong lithologies (eclogites, peridotites) speaks against the presence of large tectonic overpressure during metamorphism.
DS200512-0850
2005
Petrilli, M.Petrilli, M., Poli, G., Perugini, D., Peccerillo, A.PetroGraph: a new software to visualize, model, and present geochemical dat a in igneous petrology.Geochemistry, Geophysics, Geosystems: G3, Vol. 6, doi. 10.1029/2005 GC000932TechnologyComputer - program, PetroGraph, major, trace elements
DS1991-0283
1991
Petrini, R.Comin-Chiaramonti, P., Civetta, L., Petrini, R., Piccirillo, E.M.Tertiary nephelinitic magmatism in eastern Paraguay: petrologyEuropean Journal of Mineralogy, Vol. 3, No. 2, pp. 507-525GlobalNephelinite, ankaramite -Asuncion, Mantle nodules, geochemistry
DS1992-0113
1992
Petrini, R.Bellieni, G., Macedo, M.H.F., Petrini, R., Piccirillo, E.M.Evidence of magmatic activity related to Middle Jurassic and LowerChemical Geology, Vol. 97, No. 1/2, May 15, pp. 9-32BrazilTectonics, Geochronology
DS200712-0144
2007
PetrinovicCarlson, R.W., Aruajo, Junqueira-Brod, Gaspar, Brod, Petrinovic, Hollanda, Pimentel, SichelChemical and isotopic relationships between peridotite xenoliths and mafic-ultrapotassic rocks from southern Brazil.Chemical Geology, Vol. 242, 3-4, pp. 418-437.South America, BrazilGeochemistry
DS200712-0145
2007
PetrinovicCarlson, R.W., Aruajo, Junqueira-Brod, Gaspar, Brod, Petrinovic, Hollanda, Pimentel, SichelChemical and isotopic relationships between peridotite xenoliths and mafic-ultrapotassic rocks from southern Brazil.Chemical Geology, Vol. 242, 3-4, pp. 418-437.South America, BrazilGeochemistry
DS200512-0902
2005
Petrinovic, I.A.Ribeiro, C.C., Brod, J.A., Junqueira-Brod, T.C., Gaspar, J-C., Petrinovic, I.A.Mineralogical and field aspects of magma fragmentation deposits in a carbonate phosphate magma chamber: evidence from the Catalao I complex, Brazil.Journal of South American Earth Sciences, Vol. 18, 3-4, March pp. 355-369.South America, BrazilCarbonatite, Lagoa Seca, APIP, chamber pipes, surge
DS200812-0840
2008
Petrinovic, I.A.Palmieri, M., Pereira, G.S.B., Brod, J.A., Junquiera-Brod, T.C., Petrinovic, I.A., Ferrari, A.J.D.Orbicular magnetite from the Catalao I phoscorite carbonatite complex.9IKC.com, 3p. extended abstractSouth America, BrazilCarbonatite
DS201312-0100
2013
Petrinovic, I.A.Brod, J.A., Junqueira-Brod, T.C., Gaspar, J.C., Petrinovic, I.A., De Castro Valente, S., Corval, A.Decoupling of paired elements, crossover REE patterns and mirrored spider diagrams: fingerprinting liquid immiscibility in the Tapira alkaline carbonatite complex, SE Brazil.Journal of South American Earth Sciences, Vol. 41, pp. 41-56.South America, BrazilTapira - mineral chemistry
DS200712-0838
2007
Petrishchevsky, A.M.Petrishchevsky, A.M.Density In homogeneity of the lithosphere in the southeastern periphery of the North Asian Craton.Russian Geology and Geophysics, Vol. 48, 5, pp. 442-455.Asia, RussiaGeophysics - seismics
DS201112-0787
2011
Petrishchevsky, A.M.Petrishchevsky, A.M.Rheological model of the crust beneath southern Sikhote-Alin: evidence from gravity data.Russian Journal of Pacific Geology, Vol. 5, 3, pp. 210-224.RussiaGeophysics
DS1991-1339
1991
PetrographyPetrographyArgillaceous rock atlasSpringer-Verlag, 135p. Photographs approx. $100.00GlobalO'Brien, N.R., Slatt, R.M., Black shale
DS1998-1157
1998
PetrologyPetrologyPetrology of alkaline rocks and carbonatitesPetrology, Spec. Issue, Vol. 6, No. 3, pp. 207-312Tanzania, Siberia, India, Mongolia, FennoscandiaAlkaline rocks
DS201212-0700
2012
Petrone, C.M.Srivasta, R.K., Melluso, L., Petrone, C.M., Guarino, V., Sinha, A.K.Evolution of the Early Cretaceous alkaline Jasra complex, Shillong Plateau, northeastern India.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractIndiaDeposit - Jasra
DS202004-0515
2020
Petrone, C.M.Gibson, S.A., Rooks, E.E., Day, J.A., Petrone, C.M., Leat, P.T.The role of sub-continental mantle as both "sink" and "source" in deep Earth volatile cycles.Geochimica et Cosmochimica Acta, Vol. 275, pp. 140-162.Mantlecraton

Abstract: The extent to which Earth’s sub-continental lithospheric mantle modulates the flux of volatile elements from our planet’s deep interior to its atmosphere (via volcanism) is poorly constrained. Here, we focus on "off-craton" sub-continental lithospheric mantle because this long-lived reservoir potentially acts as both a volatile “sink” and “source” during major heating and rifting events. The sub-continental lithospheric mantle is primarily formed of peridotites with subordinate amounts of pyroxenites. While both lithologies are dominated by nominally-volatile-free mantle minerals, some of these phases have been shown to contain non-negligible amounts of H2O (e.g. 100’s of ppmw in clinopyroxene). Data for volatile elements other than Li are, however, limited. We present new, high-precision, in-situ Secondary Ion Mass Spectrometry analyses of H, F, Cl, Li and B in olivine and pyroxenes from well-characterised garnet- and spinel-bearing peridotites and pyroxenites (from southern Patagonia and the Antarctic Peninsula). Our study confirms that clinopyroxene is the main host of H2O and F. The maximum F contents we report (up to 154 ppmw) are higher than those in previous studies and occur in Ti-Cr diopsides in highly-metasomatised peridotites and Ti-Al augites from clinopyroxenite veins. Water contents of clinopyroxenes (up to 615 ppmw) are within the range previously published for continental mantle. Lithium concentrations are low (<5 ppmw) in all analysed phases and both Cl and B are below detection levels (14 ppmw and 0.03 ppmw, respectively). Unique to our study is the large variation in major- and trace-element concentrations of the clinopyroxenes, which allows us to place quantitative constraints on how volatiles are stored in the mantle. We demonstrate that: (i) F contents of clinopyroxenes closely correlate with Ti and (ii) and is systematic and inversely correlated with temperature. Despite the redistribution of volatiles during sub-solidus re-equilibration, we show that the first order control on the concentration of volatiles in clinopyroxene is the style of metasomatism, i.e. channellised flow versus reactive percolation. The mean bulk volatile contents of peridotites from Pali Aike and the Antarctic Peninsula (H2O?=?89?±?31 ppmw, F?=?16?±?11.2 ppmw and Li?=?2?±?0.7 ppmw) are within the range previously published for continental "off-craton" mantle. The pyroxenites have significantly higher mean bulk concentrations of H2O (260?±?59 ppmw), F (86?±?43 ppmw) and Li (1.0?±?0.35 ppmw). While the greater capacity of mantle pyroxenites to host H2O relative to the associated peridotites has previously been observed in global "off-craton" mantle xenolith suites (e.g. Oahu, Hawaii; eastern China and the Rio Grande Rift, SW USA), here we show for the first time that pyroxenites are also major hosts of F (but not Cl, Li or B). Because of their relatively low solidus temperatures, pyroxenites in "off-craton" settings will be readily re-mobilised during lithospheric extension (and heating). We suggest these pyroxene-rich mantle lithologies may be responsible for the elevated concentrations of H2O and F observed in basalts and volcanic gasses from major continental rift zones and flood basalt provinces, and hence an important consideration in models of global volatile cycles.
DS201212-0461
2012
Petrone, V.Melluso, L., Rajesh,K., Srivastava, C.M., Petrone, V., Guarino, V., Sinha, A.K.Mineralogy, magmatic affnity and evolution of the Early Cretaceous alkaline complex of Jasra, Shillong Plateau, northeastern India.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractIndiaDeposit - Jasra
DS201807-1510
2018
Petronis, M.S.Magee, C., Stevenson, C.T.E., Ebmeier, S.K., Keir, D., Hammond, J.O.S., Gottsmann, J.H., Whaler, K.A., Schofield, N., Jackson, C.A-L., Petronis, M.S., O'Driscoll, B., Morgan, J., Cruden, A., Vollgger, S.A., Dering, G., Micklethwaite, S., Jackson, M.D.Magma plumbing systems: a geophysical perspective. InSAR, GPS, GNSS, FWI, UAVsJournal of Petrology, in press available, 99p.Mantlemagmatism - geophysics

Abstract: Over the last few decades, significant advances in using geophysical techniques to image the structure of magma plumbing systems have enabled the identification of zones of melt accumulation, crystal mush development, and magma migration. Combining advanced geophysical observations with petrological and geochemical data has arguably revolutionised our understanding of, and afforded exciting new insights into, the development of entire magma plumbing systems. However, divisions between the scales and physical settings over which these geophysical, petrological, and geochemical methods are applied still remain. To characterise some of these differences and promote the benefits of further integration between these methodologies, we provide a review of geophysical techniques and discuss how they can be utilised to provide a structural context for and place physical limits on the chemical evolution of magma plumbing systems. For example, we examine how Interferometric Synthetic Aperture Radar (InSAR), coupled with Global Positioning System (GPS) and Global Navigation Satellite System (GNSS) data, and seismicity may be used to track magma migration in near real-time. We also discuss how seismic imaging, gravimetry, and electromagnetic data can identify contemporary melt zones, magma reservoirs, and, or, crystal mushes. These techniques complement seismic reflection data and rock magnetic analyses that delimit the structure and emplacement of ancient magma plumbing systems. For each of these techniques, with the addition of full-waveform inversion (FWI), the use of Unmanned Aerial Vehicles (UAVs), and the integration of geophysics with numerical modelling, we discuss potential future directions. We show that approaching problems concerning magma plumbing systems from an integrated petrological, geochemical, and geophysical perspective will undoubtedly yield important scientific advances, providing exciting future opportunities for the volcanological community.
DS202012-2209
2020
Petrosino, P.Buono, G., Fanara, S., Macedonio, G., Palladino, D.M., Petrosino, P., Sottili, G., Pappalardo, L.Dynamics of degassing in evolved alkaline magmas: petrological, experimental and theoretical insights.Earth-Science Reviews, Vol. 211, 103402, 23p. PdfMantlealkaline

Abstract: In the last few decades, advanced monitoring networks have been extended to the main active volcanoes, providing warnings for variations in volcano dynamics. However, one of the main tasks of modern volcanology is the correct interpretation of surface-monitored signals in terms of magma transfer through the Earth's crust. In this frame, it is crucial to investigate decompression-induced magma degassing as it controls magma ascent towards the surface and, in case of eruption, the eruptive style and the atmospheric dispersal of tephra and gases. Understanding the degassing behaviour is particularly intriguing in the case of poorly explored evolved alkaline magmas. In fact, these melts frequently feed hazardous, highly explosive volcanoes (e.g., Campi Flegrei, Somma-Vesuvius, Colli Albani, Tambora, Azores and Canary Islands), despite their low viscosity that usually promotes effusive and/or weakly explosive eruptions. Decompression experiments, together with numerical models, are powerful tools to examine magma degassing behaviour and constrain field observations from natural eruptive products and monitoring signals. These approaches have been recently applied to evolved alkaline melts, yet numerous open questions remain. To cast new light on the degassing dynamics of evolved alkaline magmas, in this study we present new results from decompression experiments, as well as a critical review of previous experimental works. We achieved a comprehensive dataset of key petrological parameters (i.e., 3D textural data for bubbles and microlites using X-ray computed microtomography, glass volatile contents and nanolite occurrence) from experimental samples obtained through high temperature-high pressure isothermal decompression experiments on trachytic alkaline melts at super-liquidus temperature. We explored systematically a range of final pressures (from 200 to 25 MPa), decompression rates (from 0.01 to 1 MPa s?1), and volatile (H2O and CO2) contents. On these grounds, we integrated coherently literature data from decompression experiments on evolved alkaline (trachytic and phonolitic) melts under various conditions, with the aim to fully constrain the degassing mechanisms and timescales in these magmas. Finally, we simulated numerically the experimental conditions to evaluate strengths and weaknesses in decrypting degassing behaviour from field observations. Our results highlight that bubble formation in evolved alkaline melts is primarily controlled by the initial volatile (H2O and CO2) content during magma storage. In these melts, bubble nucleation needs low supersaturation pressures (? 50-112 MPa for homogeneous nucleation, ? 13-25 MPa for heterogeneous nucleation), resulting in high bubble number density (~ 1012-1016 m?3), efficient volatile exsolution and thus in severe rheological changes. Moreover, the bubble number density is amplified in CO2-rich melts (mole fraction XCO2 ? 0.5), in which continuous bubble nucleation predominates on growth. These conditions typically lead to highly explosive eruptions. However, moving towards slower decompression rates (? 10?1 MPa s?1) and H2O-rich melts, permeable outgassing and inertial fragmentation occur, promoting weakly explosive eruptions. Finally, our findings suggest that the exhaustion of CO2 at deep levels, and the consequent transition to a H2O-dominated degassing, can crucially enhance magma vesiculation and ascent. In a hazard perspective, these constraints allow to postulate that time-depth variations of unrest signals could be significantly weaker/shorter (e.g., minor gas emissions and short-term seismicity) during major eruptions than in small-scale events.
DS202109-1455
2021
Petrosino, P.Buono, G., Fanara, S., Macedonio, G., Palladino, D.M., Petrosino, P., Sottili, G., Pappalardo, L.Dynamics of degassing in evolved alkaline magmas: petrological, experimental and theoretical insights.Earth Science Reviews , Vol. 211, 103402, 23p. PdfMantlegeodynamics

Abstract: In the last few decades, advanced monitoring networks have been extended to the main active volcanoes, providing warnings for variations in volcano dynamics. However, one of the main tasks of modern volcanology is the correct interpretation of surface-monitored signals in terms of magma transfer through the Earth's crust. In this frame, it is crucial to investigate decompression-induced magma degassing as it controls magma ascent towards the surface and, in case of eruption, the eruptive style and the atmospheric dispersal of tephra and gases. Understanding the degassing behaviour is particularly intriguing in the case of poorly explored evolved alkaline magmas. In fact, these melts frequently feed hazardous, highly explosive volcanoes (e.g., Campi Flegrei, Somma-Vesuvius, Colli Albani, Tambora, Azores and Canary Islands), despite their low viscosity that usually promotes effusive and/or weakly explosive eruptions. Decompression experiments, together with numerical models, are powerful tools to examine magma degassing behaviour and constrain field observations from natural eruptive products and monitoring signals. These approaches have been recently applied to evolved alkaline melts, yet numerous open questions remain. To cast new light on the degassing dynamics of evolved alkaline magmas, in this study we present new results from decompression experiments, as well as a critical review of previous experimental works. We achieved a comprehensive dataset of key petrological parameters (i.e., 3D textural data for bubbles and microlites using X-ray computed microtomography, glass volatile contents and nanolite occurrence) from experimental samples obtained through high temperature-high pressure isothermal decompression experiments on trachytic alkaline melts at super-liquidus temperature. We explored systematically a range of final pressures (from 200 to 25 MPa), decompression rates (from 0.01 to 1 MPa s?1), and volatile (H2O and CO2) contents. On these grounds, we integrated coherently literature data from decompression experiments on evolved alkaline (trachytic and phonolitic) melts under various conditions, with the aim to fully constrain the degassing mechanisms and timescales in these magmas. Finally, we simulated numerically the experimental conditions to evaluate strengths and weaknesses in decrypting degassing behaviour from field observations. Our results highlight that bubble formation in evolved alkaline melts is primarily controlled by the initial volatile (H2O and CO2) content during magma storage. In these melts, bubble nucleation needs low supersaturation pressures (? 50-112 MPa for homogeneous nucleation, ? 13-25 MPa for heterogeneous nucleation), resulting in high bubble number density (~ 1012-1016 m?3), efficient volatile exsolution and thus in severe rheological changes. Moreover, the bubble number density is amplified in CO2-rich melts (mole fraction XCO2 ? 0.5), in which continuous bubble nucleation predominates on growth. These conditions typically lead to highly explosive eruptions. However, moving towards slower decompression rates (? 10?1 MPa s?1) and H2O-rich melts, permeable outgassing and inertial fragmentation occur, promoting weakly explosive eruptions. Finally, our findings suggest that the exhaustion of CO2 at deep levels, and the consequent transition to a H2O-dominated degassing, can crucially enhance magma vesiculation and ascent. In a hazard perspective, these constraints allow to postulate that time-depth variations of unrest signals could be significantly weaker/shorter (e.g., minor gas emissions and short-term seismicity) during major eruptions than in small-scale events.
DS2002-0484
2002
PetrovFriberg, M., Juhlin, Beckolmen, Petrov, GreenPaleozoic tectonic evolution of the Middle Urals in the light of ESRU seismic experiment.Journal of the Geological Society of London, Vol.159,3,pp.295-306., Vol.159,3,pp.295-306.Russia, UralsTectonics
DS2002-0485
2002
PetrovFriberg, M., Juhlin, Beckolmen, Petrov, GreenPaleozoic tectonic evolution of the Middle Urals in the light of ESRU seismic experiment.Journal of the Geological Society of London, Vol.159,3,pp.295-306., Vol.159,3,pp.295-306.Russia, UralsTectonics
DS201112-0812
2011
PetrovPolyakova, E.A., Chakhmouradian, A.R., Siidra ,Britvin, Petrov, Spratt, Williams, Stanley, ZaitsevFluorine, yttrium and lanthanide rich cerianite from carbonatitic rocks of the Kerimasi volcano and surrounding explosion craters, Gregory Rift.Peralk-Carb 2011, workshop held Tubingen Germany June 16-18, PosterAfrica, TanzaniaCarbonatite
DS201112-0831
2010
PetrovProskurnin, V.F., Petrov, Bagdasarov, Rozinov, Tolmacheva, Larionov, Bilskaya, Gavrish, Mozoleva, PetrushkovOrigin of carbonatites of eastern Taimyr deduced from an isotopic and geochemical study of zircons.Geology of Ore Deposits, Vol. 52, 8, pp. 711-724.RussiaPetrology - carbonatites
DS201201-0861
2011
PetrovZaitsev, A.N., Chakmouradian, A.R., Sidra, O.I., Spratt, J., Williams, Stanley, Petrov, Britvin, PolyakaFlourine , yttrium and lanthaide rich cerianite (Ce) from carbonatitic rocks of the Kerimasi volcano and surrounding explosive craters Gregory Rift Tanzania.Mineralogical Magazine, Vol. 75, 6, pp. 2813-2822.Africa, TanzaniaCarbonatite
DS1988-0417
1988
Petrov, E.A.Liamkin, A.I., Petrov, E.A., Ershov, A.P., Sakovich, G.V.Production of diamonds from explosive substances.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 302, No. 3, pp. 611-613RussiaBlank
DS1988-0428
1988
Petrov, E.A.Lyamkin, A.I., Petrov, E.A., Petrov, Ye. A., Ershov, A.P.Production of diamonds from explosivesSoviet Physics, Vol. 33, No. 9, pp. 705-706. AbstractRussiaSynthetic diamonds
DS1975-0599
1977
Petrov, L.L.Petrov, L.L., et al.Boron contents of plutonic xenoliths from the Obnazhennaya and Mirkimberlite pipes.Geochemistry International, pp. 71-76.Russia, SiberiaGeochemistry, Deposit - Obnazhennaya, Mir
DS201112-0788
2010
Petrov, O.V.Petrov, O.V., Proskurin, V.F.Early Mesozoic carbonatites in folded formations of the Taimyr Peninsula.Doklady Earth Sciences, Vol. 435, 2, pp. 1592-1595.RussiaCarbonatite
DS201709-2049
2017
Petrov, O.V.Rodionov, N.V. , Lepekhina, E.N., Antonov, A.V., Petrov, O.V., Belyatsky, B.V., Shevchenko, S.S., Sergeev, S.A.Pyrochlore and baddeleyite from carbonatites of the Paleozoic polyphase Kovdor Massif ( N. Karelia).Goldschmidt Conference, abstract 1p.Russia, Kareliacarbonatite. Kovdor

Abstract: Pyrochlore is the main host of rare-metal elements of carbonatite rocks, including phoscorites, typical for prolonged history of alkaline magma crystallization at the mafic-ultramafic polyphase Kovdor massif. Pyrochlore associated with baddeleyite, zircon, zirkelite, zirkonolite and forms octahedral and cube-octahedral poikilitic crystals up to 2-5 cm, and represented by U, Ba-Sr and REE species of pyrochlore subgroup. The studied Kovdor pyrochlores are characterized by increased up to 6.5% U and an extremely high Th – up to 40%, with Th/U up to 500. Pyrochlore U-Pb SHRIMP ages of 290-364 Ma correlate with variations in U of different samples, whereas the Th and common Pb have a minor effect on this value. Obtained ages are significantly underestimated and may reflect the influence of the matrix effect or later low-temperature closing of the U-Pb pyrochlore system, as well as the actual transformations of pyrochlore crystal matrix due to the interaction with the late carbonate fluids. Thus the early pyrochlores and U-pyrochlores crystallized at 364 Ma within phoscorites and early calcite carbonatites, whereas Sr-Ba pyrochlores of late calcitedolomite carbonatite formed at 340 Ma, and Th-pyrochlore rims occured at the later stages of the interaction with metasomatizing fluids 290 m.y. ago. Kovdor baddeleyite is also charecterized by high composition heterogeneity determined by the difference in its origin from olivinites to ore-bearing foscorites and postmagmatic syenites. But baddeleyite from calcitemagnetite mineral association have uniform U: 184 ±40, Th: 6.4 ±1.7, ¦REE: 34 ±6, Hf: 7629 ± 599, Nb: 3595 ±840, Ti: 56 ±14, Y: 22 ±4 ppm, and HHf: +6.5 ±1.7 at the age of 379 ±6 Ma. The U-Pb SHRIMP age data demonstrate the concordance of all studied baddeleyite samples and the absence of a significant age difference between baddeleyites of the carbonatite phase: 379 ±3 and foscorites: 379 ±4 Ma. The weighted average age for all the studied baddeleyite samples (n = 8) is 379 ±2.4 Ma at MSWD of 0.6. This can also indicate a relatively short time-interval of magmatism in the formation of Kovdor polyphase massif which did not exceed 5 m.y. and could be related to the Devonian mantleplume activity.
DS202110-1634
2021
Petrov, O.V.Proskumin, V.F., Grakhanov, S.A., Petrov, O.V., Vasiliev, E.A., Berzon, E.I., Antonov, A.V., Sobolev, N.V.Forecast of the diamond potential of Taimyr.Doklady Earth Sciences, Vol. 499, 2, pp. 611-615.Russiadeposit - Taimyr

Abstract: Although irrefutable evidence for the presence of signs of diamondiferous kimberlite on the Taimyr Peninsula were obtained in the 1930s, it was only in 2020 that a macrodiamond (>1 mm) was first discovered in Eastern Taimyr. This was a colorless laminar crystal of a transitional shape from an octahedron to a rhombododecahedron. According to the set of features, the crystal is rare and atypical of the known primary and alluvial deposits of the Siberian Diamond Province. The find of this diamond indicates the presence of primary sources and the need for medium-scale geological survey and exploration over a large area from Anabar Bay (Pronchishchev Ridge) to the west to the Kiryaka-Tas and Tulai-Kiryaka highlands and to the northeast to Tsvetkov Cape.
DS2000-0309
2000
Petrov, P.Y.Gallet, Y., Pavlov, V.E., Petrov, P.Y.Late Mesoproterozoic magnetostratigraphic results from Siberia: Paleogeographic implications and magnetics ..Journal of Geophysical Research, Vol.105, No.7, July 10, pp.16481-Russia, SiberiaGeophysics - magnetics
DS2002-1234
2002
Petrov, P.Y.Pavlov, V.E., Gallet, Y., Petrov, P.Y., Zhuravlev, D.Z., Shatsillo, A.V.The Ui Group and Late Riphean sills in the Uchur Maya area: isotopic andGeotectonics, Vol. 36,4,pp. 278-92.GondwanaGeochronology
DS201012-0883
2010
Petrov, S.V.Zaitsev, N., Williams, C.T., Britvin,S.N., Kuznetsova, I.V., Spratt, J., Petrov, S.V., Keller, J.Kerimasite Ca3ZR2(Si)O12, a new garnet from carbonatites of Kerimasi volcano and surrounding explosion craters, northern Tanzania.Mineralogical Magazine, Vol. 74, pp. 803-820.Africa, TanzaniaCarbonatite
DS201012-0886
2010
Petrov, S.V.Zaitssev, A.N., Wenzel, T., Markl, G., Spratt, J., Petrov, S.V., Williams, C.T.Sadiman volcano, Crater Highlands, Tanzania: does it really contain melilitites and carbonatites or is it just a phonolite nephelinite volcano?International Mineralogical Association meeting August Budapest, abstract p. 559.Africa, TanzaniaPetrology
DS201112-0789
2011
Petrov, S.V.Petrov, S.V., Antonov, A.V., Golovina, T.A., Zaitsev, A.N.Mineralogy of heavy minerals concentrates from the unconsolidated deposits of Eledoi and Pello Hill volcanic cones ( Gelai volcano): first preliminary dataPeralk-Carb 2011, workshop held Tubingen Germany June 16-18, PosterAfrica, TanzaniaAlkalic
DS201112-0790
2011
Petrov, S.V.Petrov, S.V., Antonov, A.V., Golovina, T.A., Zaitsev, A.N.Mineralogy of heavy minerals concentrates from the unconsolidated deposits of Eeldoi and Pello Hill volcanic cones (Gelai volcano, northern Tanzania) prel.Peralk-Carb 2011... workshop June 16-18, Tubingen, Germany, Abstract p.111-112.Africa, TanzaniaDiamond, pyrope
DS201112-0791
2011
Petrov, S.V.Petrov, S.V., Antonov, A.V., Golovina, T.A., Zaitsev, A.N.Mineralogy of heavy minerals concentrates from the unconsolidated deposits of Eeldoi and Pello Hill volcanic cones (Gelai volcano, northern Tanzania) prel.Peralk-Carb 2011... workshop June 16-18, Tubingen, Germany, Abstract p.111-112.Africa, TanzaniaDiamond, pyrope
DS201412-1015
2014
Petrov, S.V.Zaitsev, A.N., Williams, C.T., Jeffreis, T.E., Strekopytov, S., Moutte, J., Ivashchenkova, O.V., Spratt, J., Petrov, S.V., Wall, F., Seltmann, R., Borozdin, A.P.Rare earth elements in phoscorites and carbonatites of the Devonian Kola alkaline province, Russia: examples from Kovdor, Khibina, Vuoriyarvi and Turiy Mys complexes.Ore Geology Reviews, Vol. 64, pp. 204-225.Russia, Kola PeninsulaCarbonatite
DS201412-1017
2014
Petrov, S.V.Zaitsev, A.N., Williams, C.T., Jeffries, T.E., Strekopytov, S., Moutte, J., Ivashchenkova, O.V., Spratt, J., Petrov, S.V., Wall, F., Seltmann, R., Borozdin, A.P.Rare earth elements in phoscorites and carbonatites of the Devonian Kola alkaline province, Russia: examples from Kovdor, Khibina, Vuoriyarvi and Turiy Mys complexes.Ore Geology Reviews, Vol. 61, pp. 204-225.Russia, Kola PeninsulaCarbonatite
DS201412-1019
2014
Petrov, S.V.Zaitsev, A.N., Williams, C.T., Jeffries, T.E., Strekopytov, S., Moutte, J., Ivashchenkova, O.V., Spratt, J., Petrov, S.V., Wall, F., Seltmann, R., Borozdin, A.P.Rare earth elements in phoscorites and carbonatites of the Devonian Kola alkaline province, Russia: examples from Kovdor, Khibina, Vuoriyarvi and Turiy Mys complexes.Ore Geology Reviews, in press availableRussia, Kola PeninsulaCarbonatite
DS202104-0619
2021
Petrov, S.V.Zaitsev, A.N., Spratt, J., Shtukenberg, A.G., Zolotarev, A.A., Britvin, S.N., Petrov, S.V., Kuptsova, A.V., Antonov, A.V.Oscillatory- and sector zoned pyrochlore from carbonatites of the Kerimasi volcano, Gregory rift, Tanzania.Mineralogical Magazine, Vol. Pp. 1-22. pdfAfrica, Tanzaniacarbonatite

Abstract: The Quaternary carbonatite-nephelinite Kerimasi volcano is located within the Gregory rift in northern Tanzania. It is composed of nephelinitic and carbonatitic pyroclastic rocks, tuffs, tuff breccias and pyroclastic breccias, which contain blocks of different plutonic (predominantly ijolite) and volcanic (predominantly nephelinite) rocks including carbonatites. The plutonic and volcanic carbonatites both contain calcite as the major mineral with variable amounts of magnetite or magnesioferrite, apatite and forsterite. Carbonatites also contain accessory baddeleyite, kerimasite, pyrochlore and calzirtite. Zr and Nb minerals are rarely observed in rock samples, though they are abundant in eluvial deposits of carbonatite tuff/pyroclastic breccias in the Loluni and Kisete craters. Pyrochlore, ideally (CaNa)Nb 2 O 6 F, occurs as octahedral and cubo-octahedral crystals up to 300 ?m in size. Compositionally, pyrochlore from Loluni and Kisete differs. The former is enriched in U (up to 19.4 wt.% UO 2 ), light rare earth elements (up to 8.3 wt.% LREE 2 O 3 ) and Zr (up to 14.4 wt.% ZrO 2 ), and the latter contains elevated Ti (up to 7.3 wt.% TiO 2 ). All the crystals investigated were crystalline, including those with high U content ( a = 10.4152(1) Å for Loluni and a = 10.3763(1) Å for Kisete crystals). They have little or no subsolidus alteration nor low-temperature cation exchange ( A -site vacancy up to 1.5% of the site), and are suitable for single-crystal X-ray diffraction analysis ( R 1 = 0.0206 and 0.0290; for all independent reflections for Loluni and Kisete crystals, respectively). Observed variations in the pyrochlore composition, particularly Zr content, from the Loluni and Kisete craters suggest crystallisation from compositionally different carbonatitic melts. The majority of pyrochlore crystals studied exhibit exceptionally well-preserved oscillatory- and sometimes sector-type zoning. The preferential incorporation of smaller and higher charged elements into more geometrically constrained sites on the growing surfaces explains the formation of the sector zoning. The oscillatory zoning can be rationalised by considering convectional instabilities of carbonatite magmas during their emplacement.
DS202109-1496
2021
Petrov, S.V.Zaitsev, A.N., Spratt, J., Shtukenberg, A.G., Zolotarev, A.A., Britvin, S.N., Petrov, S.V., Kuptsova, A.V., Antonov, A.V.Oscillatory- and select-zoned pyrochlore from carbonatites of the Kerimasi volcano, Gregory Rift, Tanzania.Mineralogical Magazine, Vol. 85, 4, pp. 532-553.Africa, Tanzaniadeposit - Kerimasi

Abstract: The Quaternary carbonatite-nephelinite Kerimasi volcano is located within the Gregory rift in northern Tanzania. It is composed of nephelinitic and carbonatitic pyroclastic rocks, tuffs, tuff breccias and pyroclastic breccias, which contain blocks of different plutonic (predominantly ijolite) and volcanic (predominantly nephelinite) rocks including carbonatites. The plutonic and volcanic carbonatites both contain calcite as the major mineral with variable amounts of magnetite or magnesioferrite, apatite and forsterite. Carbonatites also contain accessory baddeleyite, kerimasite, pyrochlore and calzirtite. Zr and Nb minerals are rarely observed in rock samples, though they are abundant in eluvial deposits of carbonatite tuff/pyroclastic breccias in the Loluni and Kisete craters. Pyrochlore, ideally (CaNa)Nb 2 O 6 F, occurs as octahedral and cubo-octahedral crystals up to 300 ?m in size. Compositionally, pyrochlore from Loluni and Kisete differs. The former is enriched in U (up to 19.4 wt.% UO 2 ), light rare earth elements (up to 8.3 wt.% LREE 2 O 3 ) and Zr (up to 14.4 wt.% ZrO 2 ), and the latter contains elevated Ti (up to 7.3 wt.% TiO 2 ). All the crystals investigated were crystalline, including those with high U content ( a = 10.4152(1) Å for Loluni and a = 10.3763(1) Å for Kisete crystals). They have little or no subsolidus alteration nor low-temperature cation exchange ( A -site vacancy up to 1.5% of the site), and are suitable for single-crystal X-ray diffraction analysis ( R 1 = 0.0206 and 0.0290; for all independent reflections for Loluni and Kisete crystals, respectively). Observed variations in the pyrochlore composition, particularly Zr content, from the Loluni and Kisete craters suggest crystallisation from compositionally different carbonatitic melts. The majority of pyrochlore crystals studied exhibit exceptionally well-preserved oscillatory- and sometimes sector-type zoning. The preferential incorporation of smaller and higher charged elements into more geometrically constrained sites on the growing surfaces explains the formation of the sector zoning. The oscillatory zoning can be rationalised by considering convectional instabilities of carbonatite magmas during their emplacement.
DS200512-0577
2003
Petrov, T.Krasnova, N., Petrov, T.A new rock classification system applied to ultrabasic alkaline and phoscorite carbonatite rocks.Periodico di Mineralogia, (in english), Vol. LXX11, 1. April, pp. 115-123.Classifcation - RHA rank formula
DS201112-0551
2011
Petrov, T.Krasnova, N., Petrov, T., Korolev, N.The RHA coding of mineral compositions of alkaline rocks exemplified by the nepheline syenite family.Deep Seated Magmatism, its sources and plumes, Ed. Vladykin, N.V., pp. 234-TechnologyNomenclature - rank, entropy,purity
DS1984-0586
1984
Petrov, V.P.Petrov, V.P.Nonmetallic Mineral Resources of Ancient Shields.(russian)In: Geol. Mineral resources of ancient shields, Chukhrov, F.V. editor, Izd. Nauka Moscow, USSR, pp. 109-115RussiaBlank
DS1991-1340
1991
Petrov, V.P.Petrov, V.P.The nature of thick zones of paleoweatheringInternational Geology Review, Vol. 33, No. 1, pp. 49-61RussiaLaterites -general, Geomorphology
DS1950-0494
1959
Petrov, V.S.Petrov, V.S.The Genetic Association between Diamonds and the Carbonatites of Kimberlites.Vestn. Moscow University, No. 2, PP. 13-20.RussiaBlank
DS1960-1009
1968
Petrov, V.S.Petrov, V.S.Composition of Carbon Stable Isotopes in KimberlitesVestn. Moscow University, Vol. 23, No. 4, PP. 40-44.RussiaBlank
DS1988-0428
1988
Petrov, Ye. A.Lyamkin, A.I., Petrov, E.A., Petrov, Ye. A., Ershov, A.P.Production of diamonds from explosivesSoviet Physics, Vol. 33, No. 9, pp. 705-706. AbstractRussiaSynthetic diamonds
DS1994-0489
1994
Petrova, M.Ekimova, T.E., Lavrova, L.D., Nadezhdina, E.D., Petrova, M.Conditions of the formation of the Kumdykol diamond deposit, NorthernKazakhstan.Geology of Ore Deposits, Vol. 36, No. 5, pp. 410-419.Russia, KazakhstanDiamond genesis, Deposit -Kumdykol
DS1992-1721
1992
Petrova, M.A.Yekimova, T.V., Lavrova, L.D., Petrova, M.A.Diamond inclusions in rock-forming minerals of metamorphic rocks.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 322, No. 2, pp. 366-368RussiaDiamond inclusions, Metamorphic rocks
DS1994-1965
1994
Petrova, M.A.Yekimova, T.Ye., Lavrova, L.D., Petrova, M.A.Diamond inclusions in the rock forming minerals of metamorphic rocksDoklady Academy of Sciences Acad. Science USSR, Vol. 323, No. 2, June pp. 101-103.RussiaDiamond inclusions, Metamorphic rocks
DS1995-1065
1995
Petrova, M.A.Lavrova, L.D., Pechniko, V.A., Petrova, M.A., Ekimova, T.E.Minerals - indicators of diamond in the metamorphic rocks. (Russian)Doklady Academy of Sciences Nauk, (Russian), Vol. 343, No. 2, July pp. 220-224.Russiametamorphism
DS1995-1066
1995
Petrova, M.A.Lavrova, L.D., Petchnikov, V.A., Petrova, M.A., EkimovaNew genetic type of diamond deposits: geological pecularities and originProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 311-313.Russia, KazakhstanMetamorphic, Deposit -Kumdykolskoye
DS1960-0447
1964
Petrova, M.G.Elyanov, A.A., Petrova, M.G., Solomonidina, N.L.The First Discovery of Kimberlites in the East of the Aldanshield.Izv. Vses. Ucheb. Zaved. Ser. Geol., No. 8, . PP. 123-124.RussiaBlank
DS2000-0056
2000
Petrova, T.E.Balykin, P.A., Petrova, T.E.Petrological types and genesis of komatiite basalt, picrite basalt, and picrite dolerite complexes.Russian Geology and Geophysics, Vol.41,No.8, pp. 1063-77.RussiaKomatiites, picrites
DS1982-0342
1982
Petrova, YE.N.Kogarko, L.N., Petrova, YE.N., Krigman, L.D.Strontium Fractionation During Melilite Crystallization in The System Nepheline-diopside-apatite.Doklady Academy of Science USSR, Earth Science Section., Vol. 153, No. 1-6, PP. 210-212.RussiaIsotope, Crystallography
DS201412-0682
2014
Petrovskaya, L.S.Petrovskii, M.N., Bayanova, T.B., Petrovskaya, L.S., Bazai, A.V.Mesoproterozoic peridotite-shonkinite series: a new type of intraplate magmatism in the Kola alkaline province.Doklady Earth Sciences, Vol. 457, 2, pp. 915-920.Russia, Kola PeninsulaMagmatism
DS201412-0682
2014
Petrovskii, M.N.Petrovskii, M.N., Bayanova, T.B., Petrovskaya, L.S., Bazai, A.V.Mesoproterozoic peridotite-shonkinite series: a new type of intraplate magmatism in the Kola alkaline province.Doklady Earth Sciences, Vol. 457, 2, pp. 915-920.Russia, Kola PeninsulaMagmatism
DS202104-0600
2020
Petrovskii, M.N.Petrovskii, M.N.Rare earth minerals from carbonatite veins in the Soustov pluton, Kola Peninsula, as an indicator of its ore specialization.Geology of Ore Deposits, Vol. 62, 8, pp. 754-763. pdfRussia, Kola PeninsulaREE

Abstract: This paper presents the results of the first geological, isotope, geochemical, and mineralogical study of carbonatite veins that were previously unknown in the Soustov pluton. The studied veins are similar in the Sm-Nd isotope composition and model age to the host rocks, which implies a common formation processs. High contents of light lanthanides, Sr, and Nb in carbonatite veins were measured. These elements are concentrated in bastnäsite, strontianite, monazite, and pyrochlore. These data significantly enlarge our concepts of the geochemical and ore specialization of the massif.
DS201212-0713
2012
Petrovskiy, V.A.Svortsova, V.L., Petrovskiy, V.A.,Kriulina, G.Y.Shells (imprints) of diamond in kimberlite10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractRussiaDeposit - Mir, Udachnaya
DS201312-0268
2013
Petrovsky, A.V.Filonenko, P.V., Zibrov, P.I., Petrovsky, A.V., Sukharev, E.A.Features of the formation of cubic BCN phase in comparison with natural and synthetic polycrystaline diamonds.European Journal of Mineralogy, Vol. 25, 3, pp. 373-383.TechnologyDiamond synthetics
DS201906-1356
2019
Petrovsky, V.Vasilev, E., Petrovsky, V., Kozlov, A., Antonov, A., Kudryatsev, A., Orekhova, K.The story of one diamond: the heterogeneous distribution of the optical centres within a diamond crystal from the Ichetju placer, northern Urals.Mineralogical Magazine, in press availableRussia, Uralsdiamond crystallography

Abstract: We have investigated a diamond crystal that consists of several misorientated subgrains. The main feature of the crystal is the dark in the cathodoluminescence core that has “estuary-like” boundaries extending along the subgrain interfaces. The core has more than 3100 ppm of nitrogen, and the share of the B form is more than 95%; the absorbance of the centre N3VH at 3107 cm -1 reaches 75 cm-1. The N3 centre’s absorbance, as well as N3 luminescence, is absent in the core. In the outer part of the crystal, the bright blue luminescence of the N3 centre is registered, and the N3 absorbance reaches 5.3 cm-1. These observations may be explained by the conversion of N3 centres to N3VH after attaching a hydrogen atom. After the full conversion of the N3 centres, the diamond becomes darker under CL. We hypothesize the dark core has a specific shape due to the post-growth diffusion of the hydrogen.
DS200412-1538
2004
Petrovsky, V.A.Petrovsky, V.A., Troshev, S.A., Sukharev, A.E.A mechanism of diamond formation in the presence of metals - catalysts.Doklady Earth Sciences, Vol. 397, 5, June, pp. 703-705.TechnologyDiamond genesis
DS200712-0987
2006
Petrovsky, V.A.Silaev, V.I., Petrovsky, V.A., Sukharev, A.E., Filippov, V.N.Inclusions of zircon based solid solutions in diamonds.Doklady Earth Sciences, Vol. 411, no. 8, pp. 1318-RussiaDiamond inclusions
DS200812-0888
2008
Petrovsky, V.A.Petrovsky, V.A., Silaev, V.I., Sukharev, A.E., Shamina, S.N., Martins, M., Karfunkel, J.Fluid phases in carbonado and their generic significance.Geochemistry International, Vol. 46, 7, pp. 693-710.TechnologyCarbonado
DS200812-0889
2007
Petrovsky, V.A.Petrovsky, V.A., Troshev, S.A., Sukharev, A.E.Cluster mechanism of formation of microcrystalline diamond aggregates.Doklady Earth Sciences, Vol. 417, 8, pp. 1275-1277.TechnologyDiamond morphology
DS200912-0583
2007
Petrovsky, V.A.Petrovsky, V.A., Troshev, S.A., Sukharev, A.E.Cluster mechanism of formation of micropolycrystalline diamond aggregates.Doklady Earth Sciences, Vol. 417 no. 8, pp. 1275-1277.TechnologyDiamond morphology - carbonado, ballas
DS200912-0694
2006
Petrovsky, V.A.Silaev, V.I., Petrovsky, V.A., Sukharev, A.E., Filippov, V.N.Inclusions of zircon based solid solutions in diamond.Doklady Earth Sciences, Vol. 411 no. 8, pp. 1318-1323.TechnologyDiamond inclusiosn
DS201012-0579
2010
Petrovsky, V.A.Petrovsky, V.A., Shiryaev, A.A., Lyutoev, V.P.Morphology and defects of diamond grains in carbonado: clues to carbonado genesis.European Journal of Mineralogy, Vol. 22, Feb. no. 1, pp. 35-47.MantleCarbonado
DS201012-0580
2010
Petrovsky, V.A.Petrovsky, V.A., Shiryaev, A.A., Lyutoev, V.P., Sukharev, A.E., Martins, M.Morphology and defects in diamond grains in carbonado: clues to carbonado genesis.European Journal of Mineralogy, Vol. 22, 1, pp. 35-47..MantleDiamond morphology
DS201012-0581
2010
Petrovsky, V.A.Petrovsky, V.A., Shiryaev, A.A., Lyutoev, V.P., Sukharev, A.E., Martins, M.Morphology and defects in diamond grains in carbonado: clues to carbonado genesis.European Journal of Mineralogy, Vol. 22, 1, pp. 35-47..MantleDiamond morphology
DS201012-0582
2009
Petrovsky, V.A.Petrovsky, V.A., Silaev, V.I., Sukharev, A.E., Shanina, S.N., Martins, M., Karfunkel, J.Fluid phases in carbonado and their genetic significance.Geochemistry International, Vol. 47, 7, July, pp. 693-710.TechnologyCarbonado
DS201012-0768
2010
Petrovsky, V.A.Sukharev, A.E., Petrovsky, V.A., Silaev, V.I., Martins, M.Solid inclusions in carbonados.International Mineralogical Association meeting August Budapest, abstract p. 186.TechnologyCarbonado
DS201112-0319
2011
Petrovsky, V.A.Filonenko, V.P., Petrovsky, V.A., Sukharev, A.E., Zibrov, I.P.Features of formation and structure threefold cubic B-C-N phases in comparison with microcrystals of diamond.Vestnik Komi Fan., ** in Russian english abstract, No. 1, pp. 9-16.TechnologyDiamond morphology
DS201112-0840
2010
Petrovsky, V.A.Rakin, V.I., Petrovsky, V.A., Sukharev, A.E., Martins, M.Morphological crystallography of Brazilian diamonds.Vestnik Komi FAN, **in Russian copy available, No. 10, pp. 2-7.South America, BrazilDiamond morphology
DS201212-0551
2011
Petrovsky, V.A.Petrovsky, V.A., Sukharev, A.R., Filoneneko, V.P.Crystallogenesis in heterogeneous environments.UD Ras Ekaterinburg, 274p. In RUSSIANTechnologyMineral chemistry
DS201412-0683
2014
Petrovsky, V.A.Petrovsky, V.A., Silaev, V.I., Sukharev, A.E., Vasilyev, E.A., Pomazansky, B.S., Zemnukhov, A.L.Yakutites: mineralogical geochemical properties and new version of the genesis. Part 1.Izvestiya VUZ'ov Geologia I Razvedka ** in Russia Courtesy of Felix, No. 3, pp. 24-33.Russia, YakutiaCarbonado, with lonsdaleite
DS201412-0825
2014
Petrovsky, V.A.Silaev, V.I., Petrovsky, V.A., Sukharev, A.E., Smoleva, I.V., Pomazansky, B.S., Zemnukhov, A.L.Yakutites: mineralogical geochemical properties and new version of the genesis. Part 2.Izvestiya VUZ'ov Geologia I Razvedka ** in Russia Courtesy of Felix, No. 4, pp. 12-22.TechnologyYakutites
DS201605-0883
2015
Petrovsky, V.A.Petrovsky, V.A., Silaev, V.I., Sukharev, A.E., Golubeva, I.I., Rakin, V.I., Lutoev, V.P., Vasiliev, E.A.Placer forming Diamondiferous rocks and diamonds of Eastern Brazil. IN RUSS Eng. Abs.Thesis, Vestnik Permskogo Universitecta IN RUSS, Vol. 1, 30, pp. 33-59.South America, BrazilAlluvials
DS201805-0987
2017
Petrovsky, V.A.Vasiliev, E.A., Petrovsky, V.A., Kozlov, A.V., Antonov, A.V.Infrared spectroscope and internal structure of diamonds from the Ichhetju placer ( Middle Timan, Russia).*** IN RUSProceedings of the Russian Mineralogical Society *** IN RUS, Vol. 146, 2, pp. 58-72.Russiadeposit - Ichhetju
DS201904-0794
2018
Petrovsky, V.A.Vasiliev, E.A., Petrovsky, V.A., Kozlov, A.V., Antonov, A.V.Infrared spectroscopy and internal structure of diamonds from the Ichetyu placer, central Timan, Russia.Geology of Ore Deposits, Vol. 60, 7, pp. 616-624.Russia, Uralsdiamond morphology

Abstract: A wide range of model temperature, which is typical for dodecahedroids from placer deposits in the Urals, Brazil, and the northern Yakutia diamond province has been identified in diamond crystals of the Ichetyu Ural-type diamonds deposit, Central Urals. Plates were cut from six crystals; it have been studied with cathodoluminescence and infrared and photoluminescence spectroscopy. Octahedral zoning predominates in the internal structure of rounded dodecahedroids, and growth layers are cut by the surface. Surface pigmentation spots are exhibited in the cathodoluminescent images of all plates. The nitrogen concentration in Ichetyu diamonds ranges from 100 to 2200 ppm and its proportion as B1 defects varies from 0 to 100%. The maximum absorption coefficient of hydrogen band is 56 cm-1 with an average value of 0.8 cm-1.
DS200812-0890
2008
Petrovsky, V.A.A.A.Petrovsky, V.A.A.A., Silaev, V.A.I.A., Martins, M.A., Karfunkel, J.A., Sukharev, A.A.E.A.Nanoscale mineral inclusions in the diamond phase of carbonados.Doklady Earth Sciences, Vol. 421, 2, pp. 889-892.TechnologyDiamond inclusions
DS200812-0891
2008
Petrudhin, E.I.Petrudhin, E.I., Bazarov, L.Sh., Gordeeva, V.I., Sharygin, V.V.Crystallization conditions of lamproitic magmas from Zirkel Mesa ( Leucite Hills, USA): dat a on melting experiments.9IKC.com, 3p. extended abstractUnited States, Wyoming, Colorado PlateauLamproite
DS1975-0161
1975
Petruk, W.Petruk, W., Owens, D.Electron Microprobe Analyses for Pyrochlore from Oka QuebecCanadian Mineralogist., Vol. 13, PP. 282-285.Canada, QuebecRelated Rocks, Analyses
DS1984-0429
1984
Petrukhin, V.A.Kozlov, A.A., Petrukhin, V.A., Semenov, G.S., Frantcesson, E.V.Rare and Radioactive Elements in Accessory Perovskites From the Kimberlites of Western Yakutia.Geochemistry International (Geokhimiya)., No. 11, NOVEMBER PP. 1684-1688.Russia, YakutiaUranium
DS1985-0365
1985
Petrukhin, V.A.Kozlov, A.A., Petrukhin, V.A., Semenov, G.S., Frantsesson, YE.V.Rare and radioactive elements in accessory perovskite from WestYakutiakimberlitesGeochemistry International, Vol. 22, No. 4, pp. 34-39RussiaGeochemistry
DS201012-0733
2009
Petrunin, A.G.Sobolev, A.V., Sobolev, S.V., Kuzmin, D.V., Malitch, K.N., Petrunin, A.G.Siberian meimechites: origin and relation to flood basalts and kimberlites.Russian Geology and Geophysics, Vol. 50, 12, pp. 999-1033.Russia, SiberiaMeimechite
DS201312-0704
2013
Petrunin, A.G.Petrunin, A.G., Kaban, M.K., Rogozhina, I., Trubitsyn, V.Revising the spectral method as applied to modeling mantle dynamics.Geochemistry, Geophysics, Geosystems: G3, Vol. 14, 9, pp. 3691-3702.MantleGeophysics - spectral
DS201511-1848
2015
Petrunin, A.G.Kaban, M.K., Mooney, W.D., Petrunin, A.G.Cratonic root beneath North America shifted by basal drag from the convecting mantle.Nature Geoscience, Vol. 8, 10, pp. 797-800.United States, CanadaGeophysics - seismics

Abstract: Stable continental cratons are the oldest geologic features on the planet. They have survived 3.8 to 2.5 billion years of Earth’s evolution1, 2. The key to the preservation of cratons lies in their strong and thick lithospheric roots, which are neutrally or positively buoyant with respect to surrounding mantle3, 4. Most of these Archaean-aged cratonic roots are thought to have remained stable since their formation and to be too viscous to be affected by mantle convection2, 3, 5. Here we use a combination of gravity, topography, crustal structure and seismic tomography data to show that the deepest part of the craton root beneath the North American Superior Province has shifted about 850?km to the west-southwest relative to the centre of the craton. We use numerical model simulations to show that this shift could have been caused by basal drag induced by mantle flow, implying that mantle flow can alter craton structure. Our observations contradict the conventional view of cratons as static, non-evolving geologic features. We conclude that there could be significant interaction between deep continental roots and the convecting mantle.
DS201412-0684
2015
Petrus, J.A.Petrus, J.A., Ames, D.E., Kamber, B.S.On the track of the elusive Sudbury impact: geochemical evidence for a chondrite or comet bolide.Terra Nova, Vol. 27, pp. 9-20.Canada, OntarioMeteorite
DS201502-0090
2015
Petrus, J.A.Petrus, J.A., Ames, D.E., Kamber, B.S.On the track of the elusive Sudbury impact: geochemical evidence for a chondrite or comet bolide.Terra Nova, Vol. 27, 1, pp. 9-20.Canada, OntarioMeteorite
DS201911-2535
2019
Petrus, J.A.Kamber, B.S., Petrus, J.A.The Influence of large bolide impacts on Earth's carbon cycle.Elements, Vol. 15, pp. 313-318.Mantlecarbon

Abstract: Human society's rapid release of vast quantities of CO2 into the atmosphere is a significant planetary experiment. An obvious natural process capable of similar emissions over geologically short time spans are very large bolide impacts. When striking a carbon-rich target, bolides significantly, and potentially catastrophically, disrupt the global biogeochemical carbon cycle. Independent factors, such as sulfur-rich targets, redox state of the oceans or encountering ecosystems already close to a tipping point, dictated the magnitude of further consequences and determined which large bolide strikes shaped Earth's evolution. On the early Earth, where carbon-rich sedimentary targets were rare, impacts may not have been purely destructive. Instead, enclosed subaqueous impact structures may have contributed to initiating Earth's unique carbon cycle.
DS200712-1101
2007
Petrushin, E.I.Urakaev, F.K., Shevchenko, V.S., Logvinoa, A.M., Madyukov, I.A., Petrushin, E.I., Yusupov,T.S.Sobolev.Mechano chemical processing of low grade diamond into nanocomposite materials.Doklady Earth Sciences, Vol. 415, 5, pp. 755-758.RussiaMining - mineral processing
DS200512-0851
2004
Petrushkin, E.I.Petrushkin, E.I., Bazarov, L.Sh., Shaygin, V.V., Gordeeva, V.I., Vladykin, N.V.Effect of temperature regime on crystallization of leucite from orendite melt (from experimental data).Russian Geology and Geophysics, Vol. 45, 10, pp. 1159-1166.Mineral chemistry
DS201112-0831
2010
PetrushkovProskurnin, V.F., Petrov, Bagdasarov, Rozinov, Tolmacheva, Larionov, Bilskaya, Gavrish, Mozoleva, PetrushkovOrigin of carbonatites of eastern Taimyr deduced from an isotopic and geochemical study of zircons.Geology of Ore Deposits, Vol. 52, 8, pp. 711-724.RussiaPetrology - carbonatites
DS1960-0871
1967
Petsch, B.E.Petsch, B.E.Vertical Intensity Magnetic Map of South DakotaSouth Dakota Geological Survey Map, No. 4.GlobalGeophysics, Mid-continent
DS1996-1116
1996
Petsch, E.J.Petsch, E.J.Gemstones dealing: supply, fashion and priceMineral Industry International., No. April, pp.GlobalInvestment, prices, marketing, fashion, asset, Gemstones
DS1910-0081
1910
Petterd, W.F.Petterd, W.F.Catalogue of the Minerals of Tasmania. #1Papers and Proceedings of the Royal Society of Tasmania, PP. 63-64.Australia, TasmaniaDiamond, Savage River Area
DS1991-1341
1991
Petters, S.W.Petters, S.W.Regional geology of AfricaSpringer-Verlag Lecture Notes series, Vol. 40, 722p. approx. $ 100.00AfricaGeology, tectonics, resources, Table of contents
DS1991-1342
1991
Petters, S.W.Petters, S.W.Regional geology of Africa. Birimian diamonds mentioned and alkalinecomplexes, kimberlite.General overview of African geology, tectonics, basinsetcSpringer-Verlag lecture Notes Series, Vol. 40, 722p. p. 191, 622, 636AfricaRegional geology, Specific mention in table of contents
DS200612-0869
2005
Petterson, M.G.Marker, B.R., Petterson, M.G., McEvoy, F., Stephenson, M.H.Sustainable minerals operations in the Developing World.Geological Society of London Special Publication, SP 250, 256p. aaprox. 160.00GlobalBook - resources
DS200812-0892
2008
Petterson, M.G.Petterson, M.G., Toila, D., Cronin, S.J., Addison, R.Communicating geoscience to indigenous people: examples from the Solomon Islands.Geological Society of London Special Publication, No. 305, pp. 141-161.Asia, Solomon IslandsAboriginal
DS2003-0936
2003
Petteruti Lieberknecht, A.M.Melluso, L., Morra, V., Brotzu, P., Franciosi, L., Petteruti Lieberknecht, A.M.Geochemical provinciality in the Cretaceous basaltic magmatism of northernJournal of the Geological Society of London, Vol. 160, 3, May pp. 477-88.MadagascarMagmatism - not specific to diamonds
DS200412-1296
2003
Petteruti Lieberknecht, A.M.Melluso, L., Morra, V., Brotzu, P., Franciosi, L., Petteruti Lieberknecht, A.M., Benno, L.Geochemical provinciality in the Cretaceous basaltic magmatism of northern Madagascar: mantle source implications.Journal of the Geological Society, Vol. 160, 3, May pp. 477-88.Africa, MadagascarMagmatism - not specific to diamonds
DS1994-1372
1994
Pettibone, P.J.Pettibone, P.J., Rogers, M.T.Russian mineral lawsEngineering and Mining Journal, Vol. 195, No. 7, July pp. WW 26-28RussiaLegal, Mining Laws
DS1994-1373
1994
Pettibone, P.J.Pettibone, P.J., Rogers, M.T.Russian mineral lawsEngineering and Mining Journal, Vol. 195, No. 7, July p. WW 26, 27, 28.Russia, Commonwealth of Independent States (CIS)Legal, Mineral laws
DS1995-0324
1995
Pettipas, A.R.Church, B.N., Dostal, J., Pettipas, A.R.Late Paleozoic gabbroic rocks of the Bridge River accretionary complex, southwestBC: geology and geochemistryGeologische Rundschau, Vol. 84, No. 4, pp. 710-719British ColumbiaGeochemistry, Bridge River Complex
DS200912-0584
2009
Pettit, W.Pettit, W.Geophysical signatures of some recently discovered large ( > 40ha) kimberlite pipes on the Alto Cuilo concession in northeastern Angola.Lithos, In press - available 32p.Africa, AngolaGeophysics
DS2002-0639
2002
Pettke, T.Halter, W.E., Pettke, T., Heinrich, RothenRutishauserMajor to trace element analysis of melt inclusions by laser ablation ICP MS methods of quantification.Chemical Geology, Vol.183, 1-4, pp.63-86.MantleMelt, Geochemistry - techniques, Inductively Coupled Plasma- Mass
DS200412-0991
2004
Pettke, T.Kessel, R., Ulmer, P., Pettke, T., Schmidt, M.W., Thompson, A.B.A novel approach to determine high pressure high temperature fluid and melt compositions using diamond trap experiments.American Mineralogist, Vol. 89, June pp. 1078-1086.TechnologyUHP, freezing approach
DS200412-0992
2004
Pettke, T.Kessel, R., Ulmer, P., Pettke, T., Schmidt, M.W., Thompson, A.B.Phase relations and second critical endpoint in eclogite H2O at 4-6 GPa and 900-1400C.Lithos, ABSTRACTS only, Vol. 73, p. S56. abstractMantleMineral chemistry
DS200412-0993
2004
Pettke, T.Kessel, R., Ulmer, P., Pettke, T., Schmidt, M.W., Thompson, A.B.A novel approach to determine high pressure high temperature fluid and melt compositions using diamond trap experiments.American Mineralogist, Vol. 89, 6, pp. 1078-1086.TechnologyPetrology, experimental UHP
DS200412-1380
2004
Pettke, T.Muntener, O., Pettke, T., Desmurs, L., Meier, M., Schaltegger, U.Refertilization of mantle peridotite in embryonic ocean basins: trace element and Nd isotopic evidence and implications to crustEarth and Planetary Science Letters, Vol. 221, 1-4, pp. 293-308.MantleGeochronology, melt
DS200612-0691
2005
Pettke, T.Kessel, R., Schmidt, M.W., Ulmer,P., Pettke, T.Trace element signature of subduction zone fluids, melts and supercritical liquids at 120-180 km depth.Nature, Vol. 437, pp. 724-MantleSubduction
DS200712-0711
2007
Pettke, T.Melekhova, E., Schmidt, M.W., Ulmer, P., Pettke, T.The composition of liquids coexisting with Dense Hydrous Magnesium silicates and the second critical endpoint in the MgO SiO2 H2O system.Frontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p.184.TechnologyWater
DS200712-0712
2007
Pettke, T.Melekhova, E., Schmidt, M.W., Ulmer, P., Pettke, T.The composition of liquids coexisting with Dense Hydrous Magnesium silicates and the second critical endpoint in the MgO SiO2 H2O system.Frontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p.184.TechnologyWater
DS200912-0348
2009
Pettke, T.Kaeser, B., Olker, B., Kait, A., Altherr, R., Pettke, T.Pyroxenite xenoliths from Marsabit ( northern Kenya): evidence for different magmatic events in the lithospheric mantle and interaction between peridotiteContributions to Mineralogy and Petrology, Vol. 157, 4, pp. 453-472.Africa, KenyaMagmatism
DS200912-0549
2009
Pettke, T.Olker, B., Kait, A., Altherr, R., Pettke, T.Evidence for different magmatic events in the lithospheric mantle and interaction between peridotite and pyroxenite. East African RiftPetrology, Vol. 157, 4, pp. 453-472.MantleGeothermometry
DS200912-0671
2009
Pettke, T.Scamelluri, M., Pettke, T., Van Roermund, H.L.M.Deep subduction fluids and their interaction with the mantle wedge.Goldschmidt Conference 2009, p. A1165 Abstract.MantleSubduction
DS201112-0293
2011
Pettke, T.Dvir, O., Pettke, T., Fumagalli, P., Kessel, R.Fluids in the peridotite water system up to 6GPa and 800 degreesC: new experimental constrains on dehydration reactions.Contributions to Mineralogy and Petrology, Vol. 161, 6, pp. 829-844.MantleWater
DS201112-0511
2011
Pettke, T.Kelin-BenDavid, O., Pettke, T., Kessel, R.Chromium mobility in hydrous fluids at upper mantle conditions.Lithos, Vol. 125, pp. 122-130.MantleMetasomatism
DS201112-0525
2011
Pettke, T.Klein-Bendavid, O., Pettke, T., Kessel, R.Chromium mobility in hydrous fluids at upper mantle conditions.Goldschmidt Conference 2011, abstract p.1198.MantleK-rich diamond forming fluids
DS201112-0526
2011
Pettke, T.Klein-BenDavid, O., Pettke, T., Kessel, R.Chromium mobility in hydrous fluids at upper mantle conditions.Lithos, Vol. 125, pp. 122-130.MantleMelting, metasomatism
DS202009-1615
2020
Pettke, T.Cannao, E., Scambelluri, M., Bebout, G.E., Agostini, S., Pettke, T., Godard, M., Crispini, L.Ophicarbonate evolution from seafloor to subduction and implications for deep-Earth C cycling.Chemical Geology, Vol. 546, 119626 29p. PdfMantlecarbon, subduction

Abstract: The chemical and physical processes operating during subduction-zone metamorphism can profoundly influence the cycling of elements on Earth. Deep-Earth carbon (C) cycling and mobility in subduction zones has been of particular recent interest to the scientific community. Here, we present textural and geochemical data (CO, Sr isotopes and bulk and in-situ trace element concentrations) for a suite of ophicarbonate rocks (carbonate-bearing serpentinites) metamorphosed over a range of peak pressure-temperature (P-T) conditions together representing a prograde subduction zone P-T path. These rocks, in order of increasing peak P-T conditions, are the Internal Liguride ophicarbonates (from the Bracco unit, N. Apennines), pumpellyite- and blueschist-facies ophicarbonates from the Sestri-Voltaggio zone (W. Ligurian Alps) and the Queyras (W. Alps), respectively, and eclogite-facies ophicarbonates from the Voltri Massif. The Bracco oceanic ophicarbonates retain breccia-like textures associated with their seafloor hydrothermal and sedimentary origins. Their trace element concentrations and ?18OVSMOW (+15.6 to +18.2‰), ?13CVPDB (+1.1 to +2.5‰) and their 87Sr/86Sr (0.7058 to 0.7068), appear to reflect equilibration during Jurassic seawater-rock interactions. Intense shear deformation characterizes the more deeply subducted ophicarbonates, in which prominent calcite recrystallization and carbonation of serpentinite clasts occurred. The isotopic compositions of the pumpellyite-facies ophicarbonates overlap those of their oceanic equivalents whereas the most deformed blueschist-facies sample shows enrichments in radiogenic Sr (87Sr/86Sr?=?0.7075) and depletion in 13C (with ?13C as low as ?2.0‰). These differing textural and geochemical features for the two suites reflect interaction with fluids in closed and open systems, respectively. The higher-P-metamorphosed ophicarbonates show strong shear textures, with coexisting antigorite and dolomite, carbonate veins crosscutting prograde antigorite foliation and, in some cases, relics of magnesite-nodules enclosed in the foliation. These rocks are characterized by lower ?18O (+10.3 to 13.0‰), enrichment in radiogenic Sr (87Sr/86Sr up to 0.7096) and enrichment in incompatible and fluid-mobile element (FME; e.g., As, Sb, Pb). These data seemingly reflect interaction with externally-derived metamorphic fluids and the infiltrating fluids likely were derived from dehydrating serpentinites with hybrid serpentinite-sediment compositions. The interaction between these two lithologies could have occurred prior to or after dehydration of the serpentinites elsewhere. We suggest that decarbonation and dissolution/precipitation processes operating in ancient subduction zones, and resulting in the mobilization of C, are best traced by a combination of detailed field and petrographic observations, C, O and Sr isotope systematics (i.e., 3D isotopes), and FME inventories. Demonstration of such processes is key to advancing our understanding of the influence of subduction zone metamorphism on the mobilization of C in subducting reservoirs and the efficiency of delivery of this C to depths beneath volcanic arcs and into the deeper mantle.
DS200412-1738
2004
Pettke, T.T.Scambelluri, M., Muntener, O., Ottolini, L., Pettke, T.T., Vanucci, R.The fate of B, Cl and Li in the subducted oceanic mantle and in the antigorite breakdown fluids.Earth and Planetary Science Letters, Vol. 222, 1, pp. 217-234.MantleSubduction, geochemistry
DS201412-0685
2014
Petts, D.Petts, D., Stern, R., Stachel, T., Chacko, T., Heaman, L.A nitrogen isotope fractionation factor between diamond and fluid derived from detailed SIMS analysis of an eclogitic diamond.Goldschmidt Conference 2014, 1p. AbstractTechnologyGeochronology
DS201412-0881
2014
Petts, D.Stachel, T., Stern, R.A., Petts, D., Nichols, K., Chacko, T.SIMS application to diamond research.Geological Society of America Conference Vancouver Oct. 19-22, 1p. AbstractTechnologyDiamond growth
DS201705-0877
2017
Petts, D.Sommer, H., Jacob, D.E., Stern, R.A., Petts, D., Mattey, D.P., Pearson, D.G.Fluid induced transition from banded kyanite to bimineralic eclogite and implications for the evolution of cratons.Geochimica et Cosmochimica Acta, in press available 55p.Africa, South AfricaDeposit - Roberts Victor

Abstract: Heterogeneous, modally banded kyanite-bearing and bimineralic eclogites from the lithospheric mantle, collected at the Roberts Victor Diamond mine (South Africa), show a reaction texture in which kyanite is consumed. Geothermobarometric calculations using measured mineral compositions in Perple_X allowed the construction of a P-T path showing a steep, cool prograde metamorphic gradient of 2 °C/km to reach peak conditions of 5.8 GPa and 890 °C for the kyanite eclogite. The kyanite-out reaction formed bimineralic eclogite and is probably an integral part of the mineralogical evolution of most archetypal bimineralic eclogites at Roberts Victor and potentially elsewhere. The kyanite-out reaction occured at close to peak pressure (5.3 GPa) and was associated with a rise in temperature to 1380 °C. Mass balance calculations show that upon breakdown, the kyanite component is fully accommodated in garnet and omphacite via a reaction system with low water fugacity that required restricted fluid influx from metasomatic sources. The ?18O values of garnets are consistently higher than normal mantle values. Each sample has its characteristic trend of ?18O variance between garnets in the kyanite-bearing sections and those in the bimineralic parts covering a range between 5.1‰ and 6.8‰. No systematic change in O-isotope signature exists across the sample population. Differences in garnet trace element signatures between differing lithologies in the eclogites are significant. Grossular-rich garnets coexisting with kyanite have strong positive Eu-anomalies and low Gd/Yb ratios, while more pyrope-rich garnets in the bimineralic sections have lost their positive Eu-anomaly, have higher Gd/Yb ratios and generally higher heavy rare earth element contents. Garnets in the original kyanite-bearing portions thus reflect the provenance of the rocks as metamorphosed gabbros/troctolites. The kyanite-out reaction was most likely triggered by a heating event in the subcratonic lithosphere. As kyanite contains around 100 ppm of H2O it is suggested that the kyanite-out reaction, once initiated by heating and restricted metasomatic influx, was promoted by the release of water contained in the kyanite. The steep (high-P low-T) prograde P-T path defining rapid compression at low heating rates is atypical for subduction transport of eclogites into the lithospheric mantle. Such a trajectory is best explained in a model where strong lateral compression forces eclogites downward to higher pressures, supporting models of cratonic lithosphere formation by lateral collision and compression.
DS201709-2056
2017
Petts, D.Sommer, H., Jacob, D.E., Stern, R.A., Petts, D., Mattey, D.P., Pearson, D.G.Fluid induced transition from banded kyanite to bimineralic eclogite and implications for the evolution of cratons.Goldschmidt Conference, abstract 1p.Africa, South Africadeposit - Roberts Victor

Abstract: Heterogeneous, modally banded kyanite-bearing and bimineralic eclogites from the lithospheric mantle, collected at the Roberts Victor Diamond mine (South Africa), show a reaction texture in which kyanite is consumed. Geothermobarometric calculations using measured mineral compositions in Perple_X allowed the construction of a P-T path showing a steep, cool prograde metamorphic gradient of 2 °C/km to reach peak conditions of 5.8 GPa and 890 °C for the kyanite eclogite. The kyanite-out reaction formed bimineralic eclogite and is probably an integral part of the mineralogical evolution of most archetypal bimineralic eclogites at Roberts Victor and potentially elsewhere. The kyanite-out reaction occured at close to peak pressure (5.3 GPa) and was associated with a rise in temperature to 1380 °C. Mass balance calculations show that upon breakdown, the kyanite component is fully accommodated in garnet and omphacite via a reaction system with low water fugacity that required restricted fluid influx from metasomatic sources. The ?18O values of garnets are consistently higher than normal mantle values. Each sample has its characteristic trend of ?18O variance between garnets in the kyanite-bearing sections and those in the bimineralic parts covering a range between 5.1‰ and 6.8‰. No systematic change in O-isotope signature exists across the sample population. Differences in garnet trace element signatures between differing lithologies in the eclogites are significant. Grossular-rich garnets coexisting with kyanite have strong positive Eu-anomalies and low Gd/Yb ratios, while more pyrope-rich garnets in the bimineralic sections have lost their positive Eu-anomaly, have higher Gd/Yb ratios and generally higher heavy rare earth element contents. Garnets in the original kyanite-bearing portions thus reflect the provenance of the rocks as metamorphosed gabbros/troctolites. The kyanite-out reaction was most likely triggered by a heating event in the subcratonic lithosphere. As kyanite contains around 100 ppm of H2O it is suggested that the kyanite-out reaction, once initiated by heating and restricted metasomatic influx, was promoted by the release of water contained in the kyanite. The steep (high-P low-T) prograde P-T path defining rapid compression at low heating rates is atypical for subduction transport of eclogites into the lithospheric mantle. Such a trajectory is best explained in a model where strong lateral compression forces eclogites downward to higher pressures, supporting models of cratonic lithosphere formation by lateral collision and compression.
DS201810-2342
2018
Petts, D.Lawley, C., Kjarsgaard, B., Jackson, S., Yang, Z., Petts, D., Roots, E.Trace metal and isotopic depth profiles through the Abitibi. Kirkland Lake kimberlite field.Lithos, Vol. 314-315, pp. 520-533.Canada, Ontariodeposit - Kirkland Lake

Abstract: Geophysical imaging of trans-lithospheric structures provide a spatial link between ore deposits in the crust and the underlying cratonic mantle. However, the deep lithosphere's role in ore deposit genesis remains poorly understood because remotely acquired datasets do not provide any direct constraints on the behaviour of ore elements within these mantle-roots. The abundance and behaviour of ore elements governs the metallic endowment of the cratonic mantle and the economic potential of mantle-derived magmas. Herein we present in situ electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) geochemical datasets for clinopyroxene and olivine mantle xenocrysts from the Jurassic Kirkland Lake kimberlite field, Abitibi greenstone belt, Canada. We specifically focus on unconventional trace elements, including ore elements with chalcophile and/or siderophile affinities (Ag-As-Au-Bi-Cu-Mo-Pb-Pt-Pd-Sb-Se-Sn-Te-W-Zn). Robust principal component analysis suggests that low-T, large-ion lithophile element alteration (Ba-Sr), which likely occurred during kimberlite emplacement, represents the largest source of variance for the xenocryst dataset. PT-dependent element partitioning during sub-solidus equilibration represents the second most important control on olivine and clinopyroxene chemistry. We demonstrate that least-altered, high-PT mantle silicates are, in fact, a significant mineral host for a range of ore elements (Cu-Zn ± Ag ± As ± Se ± Sn ± Mo) within equilibrated, garnet peridotite at depth (70-190 km). Statistical analysis of the raw, individual mass sweeps for each LA-ICP-MS signal suggest that the most abundant ore elements (Cu-Zn) occur predominantly as PT-dependent substitution reactions with the dominant mineral-forming elements, rather than as inclusions. A subset of high-PT olivine (160-180 km) yields Fe-Ni-S-poor and Na (Au ± Pt ± Pd)-rich compositions, which may reflect metasomatism, sulphide segregation and trapping of precious metal-bearing fluids at the base of the lithosphere. These anomalous mantle fragments possibly represent the first, direct sampling of precious metal-modified mantle peridotite beneath the Abitibi. Mid-PT olivine xenocrysts (70-120 km), which yield Mg-rich and high field-strength element-poor compositions, document a highly melt-depleted segment of mantle peridotite coincident with and below a shallow-dipping, low-seismic-velocity anomaly and conductive feature of the Kirkland Lake mid-lithosphere at 70-100 km. We speculate that the trace element signature of mid-PT xenocrysts documents the re-distribution of high-charge and incompatible elements from refractory garnet peridotite to phlogopite- and/or amphibole-bearing peridotite with conductive metasomatic up-flow zones. The rapid, sub-solidus diffusion of elements at high-T suggest that these processes likely occurred during, and/or immediately preceding, kimberlite volcanism. New in situ Pb isotope analyses of clinopyroxene xenocrysts sampled from metasomatized, low-Al garnet peridotite, however, also document ancient metasomatic events that likely pre-date Jurassic kimberlitic volcanism by at least one billion years.
DS201908-1773
2019
Petts, D.Bussweiler, Y., Giuliani, A., Greig, A., Kjarsgaard, B.A., Petts, D., Jackson, S.E., Barrett, N., Luo, Y., Pearson, D.G.Trace element analysis of high-Mg olivine by LA-ICP-MS - characterization of natural olivine standards for matrix-matched calibration and application to mantle peridotites.Chemical Geology, Vol. 524, pp. 136-157.Mantleperidotite

Abstract: The trace element composition of olivine is becoming increasingly important in petrological studies due to the ubiquity of olivine in the Earth's upper mantle and in primitive magmatic rocks. The LA-ICP-MS method allows for the routine analysis of trace elements in olivine to sub-ppm levels, but a major drawback of this method is the lack of knowledge about possible downhole fractionation effects when non matrix-matched calibration is used. In this contribution, we show that matrix-matched (i.e., olivine-based) calibration is preferable for small laser spot sizes (<100??m) due to significant laser-induced inter-element fractionation between olivine and commonly used silicate glass calibration materials, e.g., NIST SRM 612, GSD-1G and BHVO-2G. As a result, we present two Mg-rich natural olivine standards (355OL and SC-GB) that have been characterized by independent methods (EPMA, solution ICP-MS), and by LA-ICP-MS in four different laboratories. These natural olivines have been used 1) as primary standards for the matrix-matched calibration of olivine samples for most elements of interest (e.g., Li, Na, Al, P, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn), and 2) as secondary standards to assess the accuracy of results. Comparison of olivine- and silicate glass-calibrated results for natural peridotitic olivine reveals that matrix-matched calibration is essential when using small laser spot sizes (<100??m) in order to mitigate downhole fractionation effects for certain elements, especially Na, P, Mn, Co, Ni and Zn. If matrix-matched calibration is not feasible, we recommend that spot sizes of ?100??m, laser fluence of ?4.0?J/cm2, and total laser shot counts of ?250 (e.g., 5?Hz repetition rate for 50?s) are used in order to minimize fractionation effects between olivine and silicate glass calibration materials. We demonstrate the applicability of matrix-matched calibration on olivine from a suite of different mantle peridotite xenoliths sampled by kimberlites and alkali basalts from on-craton and off-craton localities.
DS202205-0726
2022
Petts, D.Veglio, C., Lawley, C.J.M., Kjarsgaard, B., Petts, D., Pearson, G., Jackson, S.E.Olivine xenocrysts reveal carbonated mid-lithosphere in the northern Slave craton.Lithos, 10.1016/j.lithos.2022.106633, 14p. PdfCanada, Northwest Territoriesolivine

Abstract: The cold, rigid, and melt-depleted mantle underlying Archean cratons plays an important role in the preservation of the overlying continental crust and is one of the main sources of diamonds. However, with the possible exception of rare earth elements (REE) and platinum group-elements (PGE), the concentrations and host mineral phases for many other critical trace elements within lithospheric mantle remain very poorly understood. Here we address that knowledge gap, presenting new electron microprobe and laser-ablation inductively-coupled-plasma mass-spectrometry results for a suite of mantle xenoliths (n = 12) and olivine xenocrysts (n = 376) from the Jericho, Muskox, and Voyageur kimberlites (northern Slave craton, Canada). Low-temperature (<1000 °C) harzburgite xenoliths and olivine xenocrysts suggest that the shallowest portions of the garnet-bearing mantle (?160 km) underlying the northern Slave craton is chemically depleted and becomes increasing re-fertilized from 160 to 200 km. High-temperature (>1000 °C) garnet and clinopyroxene crystals with Ti/Eu ratios > > 1000, and olivine xenocrysts suggest that interaction with ultramafic silicate melts is the most likely mechanism to re-fertilize melt-depleted peridotite with incompatible elements toward the base of the lithosphere (~200 km). In contrast, lower temperature garnet and clinopyroxene with Ti/Eu ratios <1000 are more likely related to metasomatism by carbonatitic melts and/or fluids. Carbonatitic metasomatism is also interpreted as the preferred explanation for the trend of Nb (4 ppm)- and Ta (185 ppb)-rich concentrations of olivine xenocrysts sampled from mid-lithosphere depths (~140 km). With the exception of a few elements that substitute into the olivine crystal structure during sub-solidus re-equilibration (e.g., Ca, Cr, Cu, Na, Sc, V, Zn), most other olivine-hosted trace elements do not systematically vary with depth. Instead, we interpret olivine-hosted trace element concentrations that are significantly above the analytical detection and/or quantification limits to reflect trapped fluid (e.g., As, Mo, Sb, Sn), base-metal sulphide (e.g., Ag, Au, Bi, Pd, Pt, Se, Te), and other mineral inclusions (e.g., U, Th) rather than enrichments of these elements due to substitution reactions or analytical artefacts. We interpret that these inclusions occur in olivine throughout the garnet stability field, but are relatively rare. As a result, these trapped carbonatitic, proto-kimberlite, and/or other ultramafic silicate melts do not represent a significant source for the suite of trace elements that become enriched to economic levels in the crust.
DS201412-0686
2013
Petts, D.C.Petts, D.C., Davis, W.J., Moser, D.E., Longstaffe, F.J.Age and evolution of the lower crust beneath the western Churchill Province: U-Pb zircon geochronology of kimberlite hosted granulite xenoliths, Nunavut.Precambrian Research, Vol. 241, pp. 129-145.Canada, NunavutGeochronology
DS201412-0687
2014
Petts, D.C.Petts, D.C., Moser, D.E., Longstaffe, F.J., Davis, W.J., Stern, R.A.1.8 billion years of fluid-crust interaction: a zircon oxygen isotope record for the lower crust, western Churchill Province, Canadian Shield.Lithos, Vol. 192-195, pp. 259-270.CanadaArchean - craton
DS201602-0231
2016
Petts, D.C.Petts, D.C., Stachel, T., Stern, R.A., Hunt, L., Fomradas, G.Multiple carbon and nitrogen sources associated with the parental mantle fluids of fibrous diamonds from Diavik, Canada revealed by SIMS microanalysis.Contributions to Mineralogy and Petrology, Vol. 171, 15p.Canada, Northwest TerritoriesDeposit - Diavik

Abstract: Fibrous diamonds are often interpreted as direct precipitates of primary carbonate-bearing fluids in the lithospheric mantle, sourced directly from common reservoirs of “mantle” carbon and nitrogen. Here we have examined fibrous growth layers in five diamonds (as three rims or “coats” and two whole-crystal cuboids) from the Diavik Diamond Mine, Canada, using in situ C- and N-isotope and N-abundance measurements to investigate the origin and evolution of their parental fluids, and in particular, to test for isotopic variability within a suite of fibrous diamonds. High-resolution growth structure information was gleaned from cathodoluminescence (CL) imaging and, in combination with the isotopic data, was used to assess the nature of the transition from gem to fibrous growth in the coated diamonds. The two cuboids are characterized by fine concentric bands of fibrous and/or milky opaque diamond, with one sample (S1719) having intermittent gem-like growth layers that are transparent and colourless. The three coated diamonds comprise octahedral gem cores mantled by massive or weakly zoned fibrous rims, with sharp and well-defined gem-fibrous boundaries. For the two cuboid samples, ? 13C and ? 15N values were ?7.7 to ?3.2 ‰ (mean ?6.3 ± 1.3 ‰; 1 SD; n = 84) and ?5.6 to ?2.1 ‰ (mean ?4.0 ± 0.8 ‰; 1 SD; n = 48), respectively. The three fibrous rims have combined ? 13C values of ?8.3 to ?4.8 ‰ (mean ?6.9 ± 0.7 ‰; 1 SD; n = 113) and ? 15N values of ?3.8 to ?1.9 ‰ (mean ?2.7 ± 0.4 ‰; 1 SD; n = 43). N-abundances of the combined cuboid-fibrous rim dataset range from 339 to 1714 at. ppm. The gem cores have ? 13C and ? 15N values of ?5.4 to ?3.5 ‰ and ?17.7 to +4.5 ‰, respectively, and N-abundances of 480 to 1699 at. ppm. Broadly uniform C- and N-isotope compositions were observed in each of the gem cores (variations of ~<1 ‰ for carbon and ~<3 ‰ for nitrogen). This limited C- and N- isotope variability implies that the gem cores formed from separate pulses of fluid that remained isotopically uniform throughout the duration of growth. Significant isotopic and abundance differences were observed between the gem and fibrous growth zones, including in one detailed isotopic profile ? 13C and ? 15N offsets of ~?2.4 and ~?3.7 ‰, respectively, and a ~230 at. ppm increase in N-abundance. Combined with the well-defined gem-fibrous boundaries in plane light and CL, these sharp isotopic differences indicate separate parental fluid histories. Notably, in the combined fibrous diamond dataset prominent C- and N-isotope differences between the whole-crystal cuboid and fibrous rim data were observed, including a consistent ~1.3 ‰ offset in ? 15N values between the two growth types. This bimodal N-isotope distribution is interpreted as formation from separate parental fluids, associated with distinct nitrogen sources. The bimodal N-isotope distribution could also be explained by differences in N-speciation between the respective parental fluids, which would largely be controlled by the oxidation state of the fibrous rim and cuboid growth environments (i.e., N2 vs. NH4 + or NH3). We also note that this C- and N-isotope variability could indicate temporal changes to the source(s) of the respective parental fluids, such that each stage of fibrous diamond growth reflects the emplacement of separate pulses of proto-kimberlitic fluid—from distinct carbon and nitrogen sources, and/or with varying N-species—into the lithospheric mantle.
DS201809-2054
2018
Petts, D.C.Lawley, C.J.M., Kjarsgaard, B.A., Jackson, S.E., Yang, Z., Petts, D.C.Olivine and clinopyroxene mantle xenocryst geochemistry from the Kirkland Lake kimberlite field, Ontario.Geological Survey of Canada, Open File 8376, 9p.Canada, Ontariogeochemistry
DS202002-0202
2020
Petts, D.C.Lawley, C.J.M., Pearson, G., Waterton, P., Zagorevski, A., Bedard, J.H., Jackson, S.E., Petts, D.C., Kjarsgaard, B.A., Zhang, S., Wright, D.Element and isotopic signature of re-fertilized mantle peridotite as determined by nanopower and olivine LA-ICPMS analyses.Chemical Geology, DOI:101016/ j.chemgeo.2020.119464Mantleperidotite

Abstract: The lithospheric mantle should be depleted in base- and precious-metals as these elements are transferred to the crust during partial melting. However, some melt-depleted mantle peridotites are enriched in these ore-forming elements. This may reflect re-fertilization of the mantle lithosphere and/or sequestering of these elements by residual mantle phase(s). Both processes remain poorly understood because of the low abundances of incompatible elements in peridotite and the nugget-like distribution of digestion-resistant mantle phases that pose analytical challenges for conventional geochemical methods. Herein we report new major and trace element concentrations for a suite of mantle peridotite and pyroxenite samples from the Late Permian to Middle Triassic Nahlin ophiolite (Cache Creek terrane, British Columbia, Canada) using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS) analysis of nanoparticulate powders and olivine. Compatible to moderately incompatible element concentrations suggest that Nahlin ophiolite peridotites represent residues after ?20% melt extraction. Pyroxenite dykes and replacive dunite bands are folded and closely intercalated with residual harzburgite. These field relationships, coupled with the presence of intergranular base metal sulphide, clinopyroxene and Cr-spinel at the microscale, point to percolating melts that variably re-fertilized melt-depleted mantle peridotite. Radiogenic Pb (206Pb/204Pb?=?15.402-19.050; 207Pb/204Pb?=?15.127-15.633; 208Pb/204Pb?=?34.980-38.434; n?=?45) and Os (187Os/188Os 0.1143-0.5745; n?=?58) isotope compositions for a subset of melt-depleted peridotite samples further support metasomatic re-fertilization of these elements. Other ore-forming elements are also implicated in these metasomatic reactions because some melt-depleted peridotite samples are enriched relative to the primitive mantle, opposite to their expected behaviour during partial melting. New LA-ICPMS analysis of fresh olivine further demonstrates that a significant proportion of the highly incompatible element budget for the most melt-depleted rocks is either hosted by, and/or occurs as trapped inclusions within, the olivine-rich residues. Trapped phases from past melting and/or re-fertilization events are the preferred explanation for unradiogenic Pb isotope compositions and Paleozoic to Paleoproterozoic Re-depletion model ages, which predate the Nahlin ophiolite by over one billion years.
DS1991-1343
1991
Petts, G.E.Petts, G.E., Coats, J.S., Hughes, N.Freeze sampling method of collecting drainage sediments for goldexplorationTransactions Institute of Mining and Metallurgy, Vol. 100, Section B, pp. B 28-B32ScotlandGeochemistry, Sampling-gold
DS200612-1212
2006
Petts, G.E.Sambrook Smith, G., Best, J., Bristow, C., Petts, G.E.Braided rivers.Blackwell Pubisher, 396p. $ 150.00Asia, EuropeBook - geomorphology
DS1985-0470
1985
Petty, W.B.Mullen, E.D., Petty, W.B.Petrologic Relations Among Syenites and Lamprophyric Rocks, arkansaw Alkalic Province.Geological Association of Canada (GAC)., Vol. 10, P. A42. (abstract.).United States, Gulf Coast, ArkansasPetrology
DS1988-0211
1988
Petukhov, I.E.Fedorenko, V.A., Petukhov, I.E.A generalized scheme for identifying effusive rocks from the Norilsk region based on petrochemical data. (Russian)Geologii i Geofiziki, (Russian), No. 6, pp. 74-85RussiaPicrite, Norilsk Region
DS200612-1087
2005
Petukhova, L.I.Petukhova, L.I., Voinova, I.P., Prikhodko, V.S.Pecularities of alkaline basaltoid mineralogy in Central Sikhote Alin terrigeneous volcanogenic siliceous complexes.Problems of Sources of deep magmatism and plumes., pp. 282-RussiaAlkalic
DS200512-0877
2004
Petukhova, L.L.Prikhodko, V.S., Petukhova, L.L., Chubarov, V.M.Pecularities of compositional variations in xenoliths of mantle spinel peridotite possible mechanisms of their formation in fold and stable areas.Deep seated magmatism, its sources and their relation to plume processes., pp. 293-301.MantleXenoliths
DS201112-0792
2010
Petukhova, L.L.Petukhova, L.L., Prikhodko, V.S.Lamprophyres of south Sikhote-Alin.Vladykin, N.V., Deep Seated Magmatism: its sources and plumes, pp. 200-RussiaLamprophyre
DS200912-0585
2009
Petukkova, L.I.Petukkova, L.I., Prikhodko, V.S.Micaeous picrites of the Sikhote Alin ridge.alkaline09.narod.ru ENGLISH, May 10, 2p. abstractRussiaDiamond potential
DS1859-0075
1842
Petzholdt, A.Petzholdt, A.Beitrage Zur Naturgeschichte des DiamantesDresden And Leipzig: Arnoldischen Buchhandlung, 57P.GlobalGemology
DS1988-0054
1988
Peucat, J.J.Bernard-Griffiths, J., Peucat, J.J., Fourcade, S., Kienast, J.R.Origin and evolution of 2 Ga old carbonatite complex(lhouhaouene, Ahaggar, Algeria:) neodymium and Sr isotopicevidenceContributions to Mineralogy and Petrology, Vol. 100, No. 3, pp. 339-348AlgeriaGeochronology, Carbonatite
DS1989-0556
1989
Peucat, J.J.Guerrot, C., Peucat, J.J., Capdevila, R., Dosso, L.Archean protoliths within early Proterozoic granulitic crust of the west European Hercynian belt: possible relics of the west African cratonGeology, Vol. 17, No. 3, March pp. 241-244West AfricaCraton, Proterozoic
DS1991-0103
1991
Peucat, J.J.Bernardgriffiths, J., Peucat, J.J., Menot, R.P.Isotopic (rubidium-strontium (Rb-Sr), uranium-lead (U-Pb) (U-Pb) and samarium-neodymium (Sm-Nd)) and trace element geochemistry ofLithos, Vol. 27, No. 1, June pp. 43-58AfricaGeochemistry, Geochronology
DS1991-1064
1991
Peucat, J.J.Martin, H., Sabate, P., Peucat, J.J., Cunha, J.C.An early Archean crustal segment (3.4 Ga) -the Sete Voltas Massif (Bahia, Brasil).(in French)Comptes Rendus de la'Academie des Sciences Serie II, Vol. 313, No. 5, August 29, pp. 531-538BrazilArchean, Craton
DS1997-0739
1997
Peucat, J.J.Martin, H., Peucat, J.J., Cunha, J.C.Crustal evolution in the early Archean of South America: example of the Sete Voltas MassifPrecambrian Research, Vol. 82, No. 1-2, March 1, pp. 35-62Brazil, BahiaArchean, Geotectonics
DS1998-1180
1998
Peucat, J.J.Potrel, A., Peucat, J.J., Fanning, C.M.Archean crustal evolution of the West African Craton: example of the Amsagaarea (Reguibat Rise).Precamb. Res., Vol. 90, No. 3-4, July 1, pp. 107-118.West AfricaCraton, crustal growth, recycling, subduction, Geochronology
DS2002-0276
2002
Peucat, J.J.Chardon, D., Peucat, J.J., Jayananda, M., Choukroune, P., Fanning, C.M.Archean granite greenstone tectonics at Kolar South India: interplay of diapirism andTectonics, Vol. 21, 3, 7-1.IndiaMagmatism - not specific to diamonds
DS200712-0227
2007
Peucat, J-J.De Souza, Z.S., Martin, H., Peucat, J-J., Jardim De Sa, E.F., De Frietas Macedo, M.H.Calc alkaline magmatism at the Archean Proterozoic transition: the Caico Complex basement ( NE Brazil).Journal of Petrology, Vol. 48, 11, pp. 2149-2185.South America, Brazil, SeridoMagmatism
DS1994-1374
1994
Peucker-Ehrebrink, B.Peucker-Ehrebrink, B., Hofmann, A.W., Hart, S.R.Hydrothermal lead transfer from mantle to continental crust: the role of metalliferous sedimentsEarth and Planetary Science Letters, Vol. 125, pp. 129-142MantleHydrothermal, Alteration
DS200712-0839
2007
Peucker-Ehrenbrink, B.Peucker-Ehrenbrink, B., Miller, M.W.Quantitative bedrock geology of Brazil.Geochemistry, Geophysics, Geosystems: G3, Vol. 8, Q05014.South America, BrazilGeology
DS2001-1183
2001
PevearVan der Pluijm, B.A., Hall, Vrolljk, Pevear, CoveyThe dating of shallow faults in the Earth's crustNature, Vol. 412, July 12, pp. 172-5.British Columbia, CordilleraStructure
DS1975-0600
1977
Pevye, A.V.Pevye, A.V., et al.Deep Seated Inclusions, Kimberlites and the Problem of Continental DriftInternational Geology Review, Vol. 19, No. 4, pp. 405-15.Russia, YakutiaTectonics
DS1993-0121
1993
Peyronneau, J.Biellmann, C., Gillet, P., Guyot, F., Peyronneau, J., Reynard, B.Experimental evidence for carbonate stability in the earth's lower mantleEarth and Planetary Science Letters, Vol. 118, pp. 31-41MantleCarbon, Diamond inclusions
DS1993-1433
1993
Peyronneau, J.Shankland, T.J., Peyronneau, J., Poirier, J-P.Electrical conductivity of the earth's lower mantleNature, Vol. 366, No. 6454, December 2, pp. 453-455.MantleGeophysics- seismics
DS1995-1151
1995
Peyronneau, J.Malavergne, V., Guyot, F., Peyronneau, J., Poirier, J-P.Distribution du fer, cobalt, nickel, entre mineraux du manteau inferieurterrestre haute pressure/temperatureCompte Rendus Sci. Paris., (in French), Vol. 320, II a, pp. 455-462.MantlePerovskite, Microscopy
DS201112-0793
2011
Peys, P.Peys, P.Tales of intrigue, swindles and heists.... Belgian Federal Police Antwerp based.... luncheon speaker.... added as a reference for interest.. mentions new bookGIA International Symposium 2011, Gems & Gemology, Summer abstract p. 106.GlobalBook - Flawless heist
DS2001-0914
2001
Peyton, V.Peyton, V., Levin, V., Ozerov, A.Mantle flow at a slab edge: seismic anisotropy in the Kamchatka regionGeophysical Research Letters, Vol. 28, No. 2, Jan. 15, pp.379-82.RussiaSubduction
DS2002-0937
2002
Peyton, V.Levin, V., Park, J., Brandon, M., Lees, J., Peyton, V., Gordeev, E., Ozerv, A.Crust and upper mantle of Kamchatka from teleseismic receiver functionsTectonophysics, Vol. 358, 1-4, pp. 233-265.MantleGeophysics - seismics
DS2003-0173
2003
Peyve, A.Brunelli, D., Cipriani, A., Ottolini, L., Peyve, A., Bonatti, E.Mantle peridotites from the Bouvet Triple Junction Region, South AtlanticTerra Nova, Vol. 15, No. 3, June pp. 194-203.Africa, South AmericaUltramafics
DS2003-0174
2003
Peyve, A.Brunelli, D., Cipriani, A., Ottolini, L., Peyve, A., Bonatti, E.Mantle peridotites from the Bouvet Triple Junction region, South AtlanticTerra Nova, Vol. 15, 3, pp. 194-203.Atlantic OceanBlank
DS200412-0229
2003
Peyve, A.Brunelli, D., Cipriani, A., Ottolini, L., Peyve, A., Bonatti, E.Mantle peridotites from the Bouvet Triple Junction region, South Atlantic.Terra Nova, Vol. 15, 3, pp. 194-203.Atlantic OceanPeridotite
DS200412-0230
2003
Peyve, A.Brunelli, D., Cipriani, A., Ottolini, L., Peyve, A., Bonatti, E.Mantle peridotites from the Bouvet Triple Junction Region, South Atlantic.Terra Nova, Vol. 15, no. 3, June pp. 194-203.Africa, South AmericaUltramafics
DS201112-0794
2010
Peyve, A.A.Peyve, A.A.Tectonics and magmatism in eastern South America and the Brazil basin of the Atlantic in the Phanerozoic.Geotectonics, Vol. 44, 1, pp. 60-75.South America, BrazilMagmatism - not specific to diamonds
DS1975-0379
1976
Peyve, A.V.Peyve, A.V., Perfilyev, A.S., Savelyeva, G.N.Depth Inclusions, Kimberlites and the Problem of Continental Drift.Sovetskaya Geologiya., No. 5, PP. 18-31.RussiaGenesis
DS201212-0658
2012
Pezzotta, F.Simmons, W.B., Pezzotta, F., Shigley, J.E., Beurlen, H.Granitic pegmatites as sources of colored gemstones.Episodes, Vol. 8, pp. 281-287.GlobalGemstones
DS201112-0846
2011
Pfaff, K.Ratschbacher, B., Pfaff, K., Marks, M., Markl, G.Geochemical trends within the lujavrites of the Ilmaussaq intrusion, SW Greenland.Peralk-Carb 2011, workshop held Tubingen Germany June 16-18, PosterEurope, GreenlandAlkalic
DS201112-0534
2011
Pfander, J.Konig, S., Munker, C., Hohl, S., Paulick, H., Barth, A.R., Lagos, M., Pfander, J., Buchl, A.The Earth's tungsten budget during mantle melting and crust formation.Geochimica et Cosmochimica Acta, Vol. 78, 8, pp. 2119-2136.MantleMelting - not specific to diamonds
DS201212-0534
2012
Pfander, J.Owona, S., Tichomirowa, M., Ratschbacher, L., Ondoa, J.M., Youmen, D., Pfander, J., Tchoua, F.M., Affaton, P., Ekodeck, G.E.New igneous zircon Pb/Pb and metamorphic Rb/Sr ages in the Yaounde Group, Cameroon, Central Africa): implications for the Central African fold belt evolution close to the Congo Craton.International Journal of Earth Sciences, Vol. 101, 7, pp. 1689-1703.Africa, CameroonGeochronology
DS201212-0535
2012
Pfander, J.Owona, S., Tichomirowa, M., Ratschbacher, L., Ondoa, W.J., Youmen, D., Pfander, J., Tchoua, F.M., Affaton, P., Ekodeck, G.E.New igneous zircon Pb/Pb and metamorphic Rb/Sr ages in the Yaounde Group ( Cameron, Central Africa): implications for the Central African fold belt evolution close to the Congo Craton.International Journal of Earth Sciences, Vol. 101, pp. 1689-1703.Africa, CameroonGeochronology
DS201412-0563
2014
Pfander, J.Mayer, B., Jung, S., Romer, R.,Pfander, J., Klugel, A., Pack, A., Groner, E.Amphibole in alkaline basalts from intraplate settings: implications for the petrogenesis of alkaline lavas from the metasomatised lithospheric mantle.Contributions to Mineralogy and Petrology, Vol. 167, 3, pp. 1-22.MantleMetasomatism
DS1996-0489
1996
Pfefferkorn, H.W.Gastaldo, R.A., DiMichele, W.A., Pfefferkorn, H.W.Out of the Icehouse into the Greenhouse: a late Paleozoic analog for modern global vegetational changeGsa Today, Vol. 6, No. 10, October pp. 1-7GlobalStratigraphy, Global greenhouse
DS2002-1669
2002
Pfender, M.Villinger, H., Grevemeyer, I., Kaul, N., Hauschild, J., Pfender, M.Hydrothermal heat flux through aged oceanic crust: where does the heat escape?Earth and Planetary Science Letters, Vol. 202, 1, pp.159-170.MantleGeothermometry
DS202011-2043
2019
Pfenninger-HorvathHorvath, L., Gault, R.A., Pfenninger-Horvath, Poirier, G.Mont Saint-Hilaire: history, geology, mineralogy.The Canadian Mineralogist, Special Publication 14, 634p. Canada, QuebecBook

Abstract: This paper introduces a special section of the Canadian Journal of Development Studies, "The Africa Mining Vision: A Manifesto for More Inclusive Extractive Industry-Led Development?" Conceived by African ministers "in charge of mineral resources" with inputs and guidance from African Union Heads of State, the Africa Mining Vision (AMV) was officially launched in February 2009. The papers presented in this special section reflect critically on progress that has since been made with operationalising the AMV at the country level across Africa; the general shortcomings of the manifesto; and the challenges that must be overcome if the continent is to derive g Taking over 20 years of meticulous preparation, László and Elsa Horváth, a duo of dedicated and dynamic amateur mineralogists, along with two researchers, Robert Gault, a mineralogist, and Glenn Poirier, a geologist, have produced the ultimate book "Mont Saint-Hilaire: History, Geology, Mineralogy". The photography captures the colors of Vásárely, the symmetry of Escher, the form of Bartók and the intricate patterns of Mandelbrot, all found here, in this miracle of nature. One cannot but marvel at how this single, small quarry contains such mineral diversity. At last count, over 434 mineral species have been found at Mont Saint-Hilaire, representing 9% of all known mineral species. The 66 type minerals first described from this locality represent 1.3 % of all mineral species, placing the Poudrette quarry in an extremely rarified class for worldwide mineral localities. Almost half, 47, of all known chemical elements are included in this mineral mix. Beginning some 124 million years ago, several million years and a variety of geological processes were needed to accomplish this assemblage. Be captivated, learn and, most of all, enjoy!reater economic benefit from its abundant mineral wealth.
DS201112-0530
2011
Pfichystal, A.Kmicek, L., Cempirek, J., Havlin, A., Pfichystal, A., Houzar, S., Kmichkova, M., Gadas, P.Mineralogy and petrogenesis of Ba Ti Zr rich peralkaline dyke from Sebkovice : recognition of the most lamproitic Varascan intrusion.Lithos, Vol. 121, 1-4, pp. 74-86.Europe, Czech RepublicLamproite
DS1999-0051
1999
Pfiffner, A.Beaumont, C., Ellis, S., Pfiffner, A.Dynamics of sediment subduction accretion at convergent margins: short termmodes, long term deformation...Journal of Geophysical Research, Vol. 104, No. 8, Aug. 10, pp. 17, 573-602.MantleTectonics, Subduction
DS1999-0195
1999
Pfiffner, O.A.Ellis, S., Beaumont, C., Pfiffner, O.A.Geodynamic models of crustal scale episodic tectonic accretion and underplating in subduction zones.Journal of Geophysical Research, Vol. 104, No. 7, July 10, pp. 15169-90.MantleGeophysics - seismics, Subduction
DS201808-1777
2018
Pflander, J.A.Pflander, J.A., Jung, S., Klugel, A., Munker, C., Romer, R.L., Sperner, B., Rohrmuller, J.Recurrent local melting of metasomatised lithospheric mantle in response to continental rifting: constraints from basanites and nephelinites/melilitites from SE Germany.Journal of Petrology, Vol. 59, 4, pp. 667-694.Europe, Germanymelilitites

Abstract: Cenozoic primitive basanites, nephelinites and melilitites from the Heldburg region, SE Germany, are high-MgO magmas (8•5-14•1?wt % MgO), with low SiO2 (34•2-47•1?wt %) and low to moderately high Al2O3 (9•0-15•5?wt %) and CaO (8•7-12•7?wt %). The Ni and Cr contents of most samples are up to 470?ppm and 640?ppm, respectively, and match those inferred for primary melts. In multi-element diagrams, all samples are highly enriched in incompatible trace elements with chondrite-normalised La/Yb?=?19-45, strongly depleted in Rb and K, with primitive mantle normalised K/La?=?0•15-0•72, and moderately depleted in Pb. The initial Sr-Nd-Hf isotope compositions (87Sr/86Sr?=?0•7033-0•7051, 143Nd/144Nd?=?0•51279-0•51288 and 176Hf/177Hf?=?0•28284-0•28294) fall within the range observed for other Tertiary volcanic rocks of the Central European Volcanic Province, whereas 208Pb/204Pb and 206Pb/204Pb (38•42-38•88 and 18•49-18•98) are distinctly lower at comparable 207Pb/204Pb (15•60-15•65). Trace element modelling and pressure-temperature estimates based on major element compositions and experimental data suggest that the nephelinites/melilitites formed within the lowermost lithospheric mantle, close to the lithosphere-asthenosphere boundary, by ?3-5% partial melting of a highly enriched, metasomatised, carbonated phlogopite-bearing garnet-lherzolite at temperatures?<1250?°C and pressures of ?2•8?GPa. This corresponds to a melting depth of less than ?85?km. Formation and eruption of these magmas, based on 40Ar/39Ar dating, started in the late Eocene (38•0 Ma) and lasted until the late Oligocene (25•4 Ma). Basanite eruptions occurred in the same area in the middle Miocene, about 7•7 Myr after nephelinite/melilitite generation has ceased, and lasted from 17•7 to 13•1 Ma. The basanites were generated at lower pressures (2•2-1•7?GPa) at similar temperatures (?1220-1250?°C) within the spinel stability field in the lithospheric mantle by 2-6% partial melting. Isotope and trace element systematics indicate that the lithospheric mantle source of the Heldburg magmas was affected by metasomatism associated with long-lasting subduction of oceanic and continental crust during the Variscan orogeny. Aqueous or supercritical fluids that formed at temperatures?<1000?°C and pressures of likely?>4?GPa infiltrated the thermal boundary layer at the base of the lithospheric mantle and imprinted a crustal lead isotope, and to a minor extent crustal Sr, Nd and Hf isotope signatures. They also reduced Nb/U, Ce/Pb, Lu/Hf, Sm/Nd, U/Pb and Th/Pb, but increased Rb/Sr and Nb/Ta and amplified the enrichment of LILE and LREE relative to HREE. This lead to the highly-enriched trace element patterns observed in both sample suites, and to overall less radiogenic 206Pb/204Pb and 208Pb/204Pb compared to other continental basalts in Central Europe, and to less radiogenic 176Hf/177Hf and 143Nd/144Nd that plot distinctly below the terrestrial mantle array. Temporal evolution of magmatism in the Heldburg region coincides with the changing Tertiary intraplate stress field in Central Europe, which developed in response to the Alpine orogeny. Magmatism was most probably caused in response to lithosphere deformation and perturbation of the thermal boundary layer, and not by actively upwelling asthenosphere.
DS1989-0794
1989
Pflug, R.Klein, H., Pflug, R., Ramshorn, Ch.Shaded perspective views by computer: a new tool for geologistsGeobyte, August pp. 16, 18-24. Database # 18148GlobalComputer, Program - perspective views
DS1992-1191
1992
Pflug, R.Pflug, R.Computer graphics in geologySpringer-Verlag, 298p. approx. $ 70.00GlobalBook -ad, Computer graphics
DS1994-1375
1994
Pgrebitsky, Y.E.Pgrebitsky, Y.E., et al.Magnetic anomaly map fo Russia and adjacent land and marine areasGeological Survey of Canada Open File, No. 2639, 1: 10, 000, 000 $ 15.00RussiaMap, Geophysics -magnetics
DS1960-0387
1963
Phadtre, P.N.Rao, P.S., Phadtre, P.N.Investigation for Diamond in Wajrakarur, Anantapur DistrictIndia Geological Survey, UNPUBL. ReportIndiaProspecting
DS1960-0388
1963
Phadtre, P.N.Rao, P.S., Phadtre, P.N.Investigation for Diamonds in Wajrakarur Area Anatapur District, A.p.India Geological Survey Program Report, FOR 1961-1963, PP.India, Andhra PradeshProspecting
DS1960-0732
1966
Phadtre, P.N.Rao, P.S., Phadtre, P.N.Kimberlite Pipe Rocks of Wajrakarur, Anantapur DistrictGeological Society INDIA Journal, Vol. 7, PP. 118-123.India, Andhra PradeshGeology
DS1900-0695
1908
Phalen, W.C.Phalen, W.C.Economic Geology of the Genova Quadrangle, Kentucky, Ohio, And West Virginia.United States Geological Survey (USGS) Bulletin., No. 349, 158P.United States, Kentucky, Ohio, West VirginiaGeology, Diamond
DS1910-0300
1912
Phalen, W.C.Phalen, W.C.Description of the Genova QuadrangleUnited States Geological Survey (USGS) ATLAS FOLIO, No. 184, 16P.Appalachia, KentuckyGeology
DS200812-1034
2008
Pham, N.Sego,D.C., Pham, N., Blowes, D., Smith, L.Heat transfer in waste rock piles at Diavik diamond mine.Northwest Territories Geoscience Office, p. 55. abstractCanada, Northwest TerritoriesDeposit - Diavik
DS201312-0705
2013
Pham, N.H.Pham, N.H., Sego, D.C., Arenson, L.U., Blowes, D.W., Amos, R.T., Smith, L.The Diavik waste rock project: measurement of the thermal regime of a waste rock test pile in a permafrost environment.Applied Geochemistry, Vol. 36, pp. 234-245.Canada, Northwest TerritoriesMining - Diavik
DS1997-0905
1997
Pham, T.D.Pham, T.D.Grade estimation using fuzzy set algorithmsMath. Geol, Vol. 29, No. 2, Feb. pp. 291-305GlobalGeostatistics, Grades
DS201910-2290
2019
Phamotse, K.M.Phamotse, K.M., Nhleko, A.S.Determination of optimal fragmentation curves for a surface diamond mine. LiqhobongThe Journal of the Southern African Institute of Mining and Metallurgy, Vol. 199, pp. 613-620.Africa, Lesothodeposit - Liqhobong

Abstract: Liqhobong Mining Development Company (LMDC) has been experiencing problems with boulders after blasting where the fragment sizes exceed the maximum of 800 mm as per mine standard. As a result, the mine has employed various methods to improve the fragmentation. The goal is to produce a run-of-mine (ROM) feed that does not choke the crusher and cause delays in production. In order to achieve this goal, fragmentation distribution within the fines and coarse envelope must be optimized through effective planning of blasting activities and accurate execution. The mine determined the fines-coarse envelope within which the entire crushing system can handle fragments using Split Desktop software. It is expected that both the predicted and actual fragmentation curves lie within that envelope for optimal fragmentation. The Kuz-Ram model with blast design parameters of 2.6 m for burden, 2.8 m for spacing, and 127 mm hole diameter was used to predict the fragmentation. The results show that the blast design parameters may need altering to achieve optimum fragmentation. Furthermore, the execution of the drilling and blasting may be the cause of the fragmentation problems. The mean fragmentation size (X50) differs greatly, unlike the uniformity index (n)s values which are relatively close to each other (0.6 to 2.2). The mean squared error (MSE) values have a large range. A proposed solution is a modified burden, spacing, and hole diameter. It is concluded that blast design parameters need to be reviewed in order to obtain correct predictions.
DS1997-0026
1997
Phang, C.Anand, R.R., Phang, C., Wildman, J.E., Lintern, M.J.Genesis of some calcretes in the southern Yilgarn Craton: implications for mineral explorationAustralian Journal of Earth Sciences, Vol. 44, No. 1, Feb. pp. 87-104AustraliaCraton, Calcretes
DS201809-2076
2018
Phani, P.R.Phani, P.R., Srinivas, M.Petrogenesis and diamond prospectivity of kimberlites of Anumpalli cluster, Wajrakarur field, southern India.Goldschmidt Conference, 1p. AbstractIndiadeposit - Anumpalli

Abstract: The Wajrakarur kimberlite field (WKF) records >45 pipes so far, majority being diamodiferous. In addition to pipe-10 (Anumpalli) and 11 (Dibbasanipalli) discovered by the Geological Survey of India, of late, Rio Tinto Group has discovered three more outcropping pipes in this area (east of Dibbasanipalli, west of Anumpalli and Khaderpet) and termed all these five pipes as Anumpalli kimberltie cluster (AKC). The AKC pipes contain crustal granitoid xenoliths. The Khaderpet and Dibbasanipalli east pipes show effects of fenitisation in the country rock granitoids and are intensely chloritised kimberlite granite breccias; however, the former is unique in having its association with carbonatite (sovite) intrusion. Petrographically, the AKC kimberlites exhibit inequigranular texture resulted by anhedral to subhedral olivine macrocrysts and pseudomorphs, phenocrysts of Crdiopside, ilmenite, perovskite and minor or no amounts of phologopite with two generations of olivine within a finegrained matrix of same mineral phases. Based on the major element geochemistry the AKC pipes are classified as Group- I archetypal. Based on trace element modeling, the AKC pipes appear to be originated form garnet lherzolite source with residual garnet of 0.5 to 5%, associated with stable continental and/or orogenic area and remarkably belong to non-subduction environment. The observed LREE enrichment and low HREE cencentrations in the AKC, is consistent with inferior degrees of partial melting (0.1 to 2%). The AKC pipes appear to have originated from a hydrous magma enriched in volatiles. Exploration evidences support that kimberlites of the AKC are diamodiferous. The calculated diamond grade (DG) values of the AKC pipes are high (3.43 to 8.48) which are inversely proportional to the TiO2 content. In the binary diagram of Ta and Sc (ppm), the AKC pipes plot in the field of ‘Fe-Ti diamondiferous kimberlites’. In the Fe2O3 (wt %) vs. Y (ppm) diagram, the AKC pipes plot in the ‘prospective’ field. The diamondiferous nature of the AKC pipes indicates the conditions of diamond preservation at metastable phases in crustal environment during rapid ascent of kimberlite melt to the surface from the deep mantle, which is supported by low density and ultralow viscosity of these intrusions.
DS201909-2075
2019
Phani, P.R.Phani, P.R.Restoring the past glory of diamond mining in south India - a plausible case of diamondiferous Wajrakarur kimberlite pipe clusters with geochemical evidences.International Journal of Mining and Geo-Engineering, Vol. 53, 2, pp. 1-11. pdfIndia, Andhra Pradeshdeposit - Wajrakarur

Abstract: A plausible case of collective and economical mining of diamondiferous kimberlite deposits of Wajrakarur and adjoining places in Andhra Pradesh, southern India, along with the whole-rock geochemical evidences in support of their diamond potentiality are discussed in this article. The kimberlites/lamproites are mantle-derived ultrabasic rocks which rarely carry diamonds from mantle to the earth's surface through carrot-shaped intrusions referred to as pipes. Even though few hundreds of diamondiferous kimberlite pipes were discovered in India so far, there is no other production unit than Panna diamond mine in the country where primary rock is mined. In ancient India, diamond mining in south India in the Krishna river valley was well-known to the world fascinated by famous gemstones like Koh-i-Noor, Hope, Darya-e-Noor, Noor-ul-ain etc. which were mainly extracted from alluvium or colluvium in Krishna river valley. Having bestowed with more than 45 kimberlite pipes, the Wajrakarur kimberlite field (WKF) forms a favourable region for initiating diamond mining in the country. Geochemically, majority of the WKF show low TiO2 content and considerably high diamond grade (DG) values (>3) except some pipes viz., P-5 (Muligiripalli), P-13 (Tummatapalli) and P-16 (Pennahobilam) are barren due to high TiO2 and ilmenite contents. The TiO2 content (0.66-6.62 wt %) is inversely proportional to the DG (3.33 to 22.13). The DG value of some of the WKF pipes is close to that of Panna (8.36). The cationic weight% values clearly portray the diamondiferous nature of these deposits. The WKF pipes were also proved to be diamondiferous by exploratory drilling and bulk sample processing results by the government and multinational organisations. In southern India, due to several reasons, diamond mining has not seen its initiation and impetus till now although it records a considerable number of fertile kimberlite pipes at Wajrakarur, Lattavaram, Chigicherla, Timmasamudram etc. Though the majority of WKF diamondiferous kimberlite deposits in Wajrakarur are small in their areal extent (0.06-4.48 Ha) some of them are large (>10 Ha up to 120 ha). They occur in close proximity to each other offering feasibility for collective mining and winning the precious stone through a central processing unit by deploying the latest processing technologies. The geographic conditions of this region such as availability of human resources, water resources, vast open lands, wind power generation etc. also support to initiate mining of kimberlite pipes in this area. The availability of rough diamonds produced from local mines will make the polishing industry to meet its business needs during circumstances of the shortage of rough stone influx from foreign. Hence, although it demands liberal investments, reviving diamond mining in southern India can be materialised with a meticulous evaluation of these deposits ascertaining profitability. This will certainly help to restore the past glory of diamond mining in the southern part of the subcontinent.
DS201506-0291
2015
Phani, P.R.C.Phani, P.R.C.Area selection for diamond exploration based on geological and morphostructural set-up: examples from Wajrakarur kimberlite field, India.Journal of Advanced chemical sciences, Vol. 1, 3, pp. 102-106.IndiaDeposit - Wajrakarur
DS201712-2718
2017
Phani, P.R.C.Phani, P.R.C.Petrology and geochemistry of kimberlites from Lattavaram and Anumpalli clusters Anantapur district Anfhra Pradesh India.Thesis, Phd. Osmania University 258p., http://shodhganga.inflibnet.ac.in/handle/10603/178609.India, Andhra Pradeshdeposit - Lattavaram, Anumpalli

Abstract: The thesis is organized into six chapters. The first chapter enunciates general concepts of kimberlite geology covering literature, previous work, definitions, classification, mode of occurrence, regional geological history, global and Indian occurrences of kimberlites. The second chapter elucidates the common principles and practices applied and adopted in diamond exploration applicable to the Indian context, to some extent exemplifying the kimberlite clusters of the study area. A six-stage exploration strategy, applicable to Indian geological scenario, has been proposed. The third chapter portrays the general geological setting of the study area comprising Lattavaram and Anumpalli kimberlite clusters along with spatial morphologies of the pipes and various field geological characteristics illustrated through field photographs. The fourth chapter describes various mineralogical and petrographic characteristics observed in the pipes and their associated calcretes as well of the study area emphasising their genetic significance. The fifth chapter characteristically articulates the whole rock geochemistry with the aid of major, trace and rare earth element analyses to depict the classification of the pipes under study. This chapter also demonstrates calcrete geochemistry of calcretes associated with the kimberlite pipes of the study area in detail, perhaps for the first time. The sixth chapter describes the petrogenetic inferences including source region, partial melting, temperature, density and viscosity etc., derived from geochemical analyses and thereby demonstrates the diamond prospectivity of Lattavaram and Anumpalli kimberlite pipes. In a nutshell, this research work aims to present a detailed account of petrography, geochemistry, petrogenesis and diamond prospectivity of kimberlites from Lattavaram and Anumpalli clusters in light of recently discovered pipes. For the first time, petrographic and geochemical analyses of kimberlitic calcretes are presented and interpreted.
DS201712-2719
2017
Phani, P.R.C.Phani, P.R.C., Srinivas, M.Quantitative study of indicator minerals on kimberlite pipe-5 at Muligiripalli, Wajrakarur field, southern India. Preliminary results of loam sampling.Russian Mineralogical Society 200th. Anniversary meeting Oct. 10-13., 4p. Abstract pdfIndiadeposit - Pipe-5, Wajrakakarur

Abstract: In an attempt to study the kimberlite indicator minerals (KIMs), loam sampling in the close vicinity of the pipes has been carried out on some kimberlites of the WKF. In this paper, preliminary results of KIMs derived out of loam sampling on one of the WKF pipes at Muligiripalli (pipe-5) are presented. Surface loam sampling has been carried out in the topographically low-lying areas in the close proximity of the pipe outcrop. Four composite samples, at a spacing of ~100 meters, weighing 25 kg each have been collected and sieved through 1 mm mesh. Approximately 5 kg of ‘-1’ fraction has been obtained after sieving which is further subjected to coning and quartering. The material has been subjected to heavy mineral (HM) separation using a manual jig. The HM further screened through Frantz’s isodynamic separator to separate magnetic mineral grains. The HM assemblage includes ilmenite, chromite, Cr-diopside, olivine and sphene. ). To ascertain the kimberlitic nature of the HM grains and thereby to check diamondiferous nature of this pipe, additonal loam sampling to obtain more number of mineral grains to carry out Electron Microprobe Analysis (EPMA) is planned.
DS201801-0046
2017
Phani, P.R.C.Phani, P.R.C.A new kimberlite pipe in Balkamthota Vanka, Pennahobilam, Anantapur district, Andhra Pradesh, India - field aspects and preliminary investigations.periodicomineralogia.it, Vol. 86, 3, 7p.India, Andhra Pradeshdeposit - Balkamthota Vanka

Abstract: Systematic closely spaced geological traverses conducted in the year 2010, in Lattavaram Kimberlite Cluster (LKC) of Anantapur district, Andhra Pradesh, India, have led to the discovery of a new kimberlite pipe outcrop in the river bed of Balkamthota Vanka (name of the stream used by local farmers) at its confluence with Penna River, close to Pennahobilam. This new pipe occurs at a distance of 1.5 km in NE direction to hitherto reported pipes-5 and 13 occurring at Muligiripalli and Tummatapalli respectively in the LKC of the Wajrakarur Kimberlite Field (WKF). With this pipe, the total number of kimberlite pipes in the WKF raises to 48, considering all the kimberlites discovered by various public and private organizations so far. Preliminary petrography, geochemistry, petrogenetic aspects and diamond prospectivity of the new occurrence have been presented here. Mineralogically, the kimberlite constitutes olivine macrocrysts, serpentinsed olivine psuedomorphs with xenocrystic ilmenite, phlogopite, perovskite, magnetite, Cr-diopside, garnet along with calcite veins. The kimberlite is classified as hypabyssal macrocrystic calcite- phlogopite kimberlite. Mineralogically, the new kimberlite pipe appears as archetypal Group- I kimberlite however, geochemically; the kimberlite shows character of both Group- I and II varieties, more close to lamproitic character. Although it is too early to comment, based on limited analyses carried out in this study, the diamond potentiality of this pipe is not encouraging; it is noteworthy that it highly warrants detailed investigations involving bulk rock geochemistry and drilling to assess its definite geochemical status, petrogenesis and diamond potentiality.
DS201808-1778
2018
Phani, P.R.C.Phani, P.R.C.Role of trace element pedogeochemistry in diamond exploration - a first report from Lattavaram kimberlite cluster, Wajrakarur field, eastern Dharwar craton, southern India.Geochimica Brasiliensis, Vol. 32, 1, pp. 95-114.Indiadeposit - Lattavaram

Abstract: Trends in concentration of selected trace elements in residual soils on four known diamondiferous kimberlite pipes (3, 4, 8 and 9) occurring at Lattavaram within the Wajrakarur Kimberlite Field (WKF) is attempted for the first time. The pipes 3 and 4 are exposed whereas the 8 and 9 are concealed under calcrete and colluvium. For this purpose, elements like Nb, Cr, Ni, Co, Zr, Mg, Sr and La are used to understand their concentrations in the kimberlitic soils in comparison with background granitic soils. It is observed that the soils on kimberlite pipes show conspicuous enrichment of elements such as Cr, Co, Nb, Ni, Mg and Sr when compared to soils in the country rock granitoid. However, no much variation in the elements La and Zr patterns between the kimberlitic and background soils is noticed. The high pulse in trace elements in kimberlitic soils is attributed to the presence of primary kimberlitic minerals and their weathered products in the soil. This particular aspect of pedogeochemistry is envisaged to be useful as an exploration tool in search of kimberlites in cratonic parts of southern India. An enrichment of Nb content upto 45 ppm in residual soils may be considered as anamolous in the craonic parts of Indian subcontinent, which needs to be confirmed and taken forward in conjunction with high resolution geological mapping, geophysics followed up by drilling for confirmation of kimberlite/lamproite occurrence.
DS201902-0307
2019
Phani, P.R.C.Phani, P.R.C., Srinivas, M.Context for diamond exploration in Telangana state through a holistic petrological appraisal of kimberlite clan rocks ( KCR).Earth, Ocean, Atmospheric & Environmental Sciences, 1p. Abstract EOAES-0-14Indiacraton

Abstract: The abstracts broadly summarises petrological aspects of kimberlite clan rocks so far discovered in the Telangana state in light of recent finds emphasising the context for diamond exploration in the state. This was presented in the '1st Telangana Science Congress (TSSC)-2018' organised by the Telangana Academy of Science, Hyderabad and National institute of Technology, Warangal (22-24, December, 2018).
DS202008-1433
2020
Phani, P.R.C.Phani, P.R.C., Lira, R., Espeche, M.J., Reddy, R.A.Geochemical and petrological studies of a magmatic carbonate-bearing metalamprophyre ( spessartite) at Kalagalla - evidence for shoshonitic calc-alkaline magmatism within auriferous Ramagiri-Penakacherla schist belt ( 2.5Ga), eastern Dharwar craton, southGeochimica Brasiensis, Vol. 34, 1, pp. 1-27. pdfIndia, Andhra Pradeshlamprophyres

Abstract: Geochemical and petrological characteristics of lamprophyre dykes at Kalagalla intruded into the auriferous schistose rocks of the Ramagiri- Penakacherla Schist Belt, Anantapur district, Andhra Pradesh, India are presented here. The Kalagalla lamprophyre (KGL) is a melanocratic rock exhibiting typical knobby or pustular texture on the surface. The microtextures and mineralogy typical of lamprophyres are obscured by metamorphism; however, it exhibits porphyritic, nemato-granoblastic texture representative of greenschist facies of metamorphism. The rock is sheared and possesses several globules formed by polycrystalline aggregates of calcite rimmed by coronitic subhedral plagioclase and biotite, evidencing its mantle-magmatic origin. The mineral assemblages noticed in thin-sections include amphibole, plagioclase, biotite, phlogopite and calcite ocelli as essential while apatite, zircon, magnetite, ilmenite, Ni-bearing chalcopyrite and pyrite as accessory phases. The SEM-EDS investigation on the accessory minerals revealed accessory sulphide and silicate phases like As-free pyrite, haematitised Ni-bearing chalcopyrite and Ni-As-Co- minerals indicative of sulphidation associated with greenstone auriferous lodes, along with silicates like LREE-bearing titanite partially transformed into leucoxene and oxide phases like magnetite altered to goethite at places. Based on mineral chemistry, whole rock geochemistry, presence of amphibole and dominance of plagioclase, the KGL is classified as a calc-alkaline variety in general and as spessartite in particular possessing shoshonitic affinity. No anomalous chemical composition is noticed in the ocellar calcite. The LREE-bearing titanite appears to be the contributor of LREE enrichment. The high Mg# (77- 79), Ni (153-162 ppm) and Cr (380-470 ppm) support a mantle source. The absence of Eu anomaly reflects lack of plagioclase fractionation. The high Zr/Hf ratio (163-202) indicates absence of crustal contamination and contribution of magmatic carbonate at the source to form ocelli as product of late-stage liquid silicate-carbonate immiscibility of segregation mechanism. The trace and REE patterns (?REE: 326-343 ppm, LREE>HREE) indicate involvement of residual garnet at the source presumably enriched in phlogopite in a ‘subduction-related’ environment.
DS201711-2525
2017
Phani, R.Phani, R.Kimberlite indicator minerals in Nutimadugu catchment, Anantapur district, Andhra Pradesh, India.Proceedings of XXXIV held Aug. 4-9. Perchuk International School of Earth Sciences, At Miass, Russia, 1p. AbstractIndiamineral chemistry

Abstract: The present study examines an unexplored catchment (60 Sq. Km.) at Nutimadugu village, in Anantapur district, on the right bank of Penna River (Fig.1), to attest the occurrence of kimberlite indicator minerals (KIMs). The left bank is famous for diamondiferous kimberlites known as Timmasamudram Kimberlite Cluster. About eight stream sediment samples (~15kg in weight), were collected from the catchment with an approximate sample sapcing of one kilometer. The -1mm fraction of the stream sediments was reduced to heavy mineral concentrate (HMC) using traditional techniques. The selected mineral grains were probed for major elements using electron probe microanalysis (EPMA). Majority (75%) are chromite grains. Uvaravite and grossularite garnets and few grains of ilmenite are also present. The chromite grains plot in the world wide kimberlitic chromite field, with few in the diamond inclusion field (Fig.2 & 3). The garnet grains plot in the G12 field and found to be wehrlitic in character (Fig.4 & 5). On the contrary, the ilmenite grains plot in the non-kimberlitic field (Fig. 6), which might have been derived from the supracrustal rocks occurring to the east of the catchment. Thus this study highlights that the catchment stands as a priority target for further field investigations.
DS201805-0971
2018
Phani, R.Phani, R., Raju, V.V., Srinivas, M.Petrological and geochemical characteristics of a shoshonitic lamprophyre, Sivarampet, Wajrakarur, kimberlite field, southern India.Journal of Applied Geology and Geophysics (IOSR), Vol. 6, 2, pp. 55-69. pdfIndiashoshonite

Abstract: Field geological, petrographic and geochemical characteristics of a lamprophyre intrusion, presumably of plug-type, at Sivarampet (SPL), occurring within the Wajrakarur kimberlite field (WKF) to the west of Cuddapah basin, are presented and discussed. The lamprophyre intrusion occurs as brecciated outcrop with angular country rock granitoid clasts and also it forms stringers/veinlets within the granitic country rock. The melanocratic rock displays panidiomorphic/porphyritic texture, typical of lamprophyres, comprising clinopyroxene, biotite, phlogopite set in a groundmass of feldspar, magnetite and spinel. Plagioclase is dominant feldspar. The K2O/Na2O ratio ranges from 1.55 to 1.89 wt %, making it distinctly potassic and brings out its shoshonitic behaviour. The fractionated chondrite normalised patterns of REE (with average (La/Yb)N= 21.01 ppm) implies involvement of an enriched mantle source while depleted values of Nb, Hf, Th and U concentrations indicate prevalence of subducted component in the mantle source. The concentrations of Rb, Sr and Ba indicate presence of phlogopite in the source. Based on the mineral assemblages, the SPL can be classified as calc-alkaline variety; however, its geochemistry shows characteristics of both alkaline and calc-alkaline varieties. The moderate Mg# (52 to 55.6) and low concentration of Ni (95.61 to 112.4 ppm) in the bulk rock indicate a low degree of partial melting of magmatic fluid from enriched asthenospheric mantle which underwent fractionation of olivine and pyroxene, subsequently producing lamprophyre magma. Recent discovery of diamonds in shoshonitic lamprophyres of Canada, appeals further investigations on diamondiferous nature of similar rock types of the WKF.
DS201805-0972
2017
Phani, R.Phani, R., Raju, V.V.N.A new kimberlite pipe in Balkamthota Vanka, Pennahobilam, Anantapur district, Andhra Pradesh, India. Field aspects and preliminary investigations.Periodico di Mineralogia, Vol. 86, pp. 213-228. pdfIndiadeposit - Balkamthota Vanka

Abstract: Systematic closely spaced geological traverses conducted in the year 2010, in Lattavaram Kimberlite Cluster (LKC) of Anantapur district, Andhra Pradesh, India, have led to the discovery of a new kimberlite pipe outcrop in the river bed of Balkamthota Vanka (name of the stream used by local farmers) at its confluence with Penna River, close to Pennahobilam. This new pipe occurs at a distance of 1.5 km in NE direction to hitherto reported pipes-5 and 13 occurring at Muligiripalli and Tummatapalli respectively in the LKC of the Wajrakarur Kimberlite Field (WKF). With this pipe, the total number of kimberlite pipes in the WKF raises to 48, considering all the kimberlites discovered by various public and private organizations so far. Preliminary petrography, geochemistry, petrogenetic aspects and diamond prospectivity of the new occurrence have been presented here. Mineralogically, the kimberlite constitutes olivine macrocrysts, serpentinsed olivine psuedomorphs with xenocrystic ilmenite, phlogopite, perovskite, magnetite, Cr-diopside, garnet along with calcite veins. The kimberlite is classified as hypabyssal macrocrystic calcite- phlogopite kimberlite. Mineralogically, the new kimberlite pipe appears as archetypal Group- I kimberlite however, geochemically; the kimberlite shows character of both Group- I and II varieties, more close to lamproitic character. Although it is too early to comment, based on limited analyses carried out in this study, the diamond potentiality of this pipe is not encouraging; it is noteworthy that it highly warrants detailed investigations involving bulk rock geochemistry and drilling to assess its definite geochemical status, petrogenesis and diamond potentiality.
DS201907-1568
2018
Phani, R.Phani, R., Srinivas, M.The calcrete geochemistry in identifying kimberlite lamproite exploration targets - a case study from Nalgonda district, Telangana, southern India.International Journal of Trend in Scientific Research and Development, Vol. 2, 2, pp. 964-975. pdfIndialamproite

Abstract: The pedogenic carbonates, found mainly in arid and semi-arid regions of the world, are commonly referred to as calcretes or caliche or kankar authigenic carbonate products which occur in association with soil, forming the residual regolith. Many rock types can produce calcretes upon weathering and denudation, but calcrete derived from certain rocks like kimberlite/lamproite acts as an exploration guide. Calcrete is a prominent sampling medium in diamond-rich countries like Australia and South Africa whereas it has not received popularity in the Indian context. Kimberlites being ultrapotassic in nature and owing to the enrichment of olivine and serpentine often produce calcrete duricrust as a capping. Recently more than twenty lamproites have been discovered in the Telangana state by the Geological Survey of India. These occurrences unravel a new panorama that the state has a substantial potential for occurrence of more kimberlite/lamproite clan rocks. An attempt has been made here to test the geochemical affinity of calcretes from various locations within Nalgonda district. The geochemical data of calcrete samples of this study has been compared with published geochemical data of lamproites of Ramadugu Field, to understand their geochemical association to kimberlite/lamproite. The calcretes are low in SiO2 (33.92-45.1 wt %), high in K2O (1.07-2.21 wt %) and CaO (0.78 When compared to other major elements, MgO displays low concentration. The trace elements are found to be enriched in some of the samples collected in close vicinity of known lamproite occurrences. The samples show high degree of chemic alteration and compositional variation indices. It is observed that enrichment of elements like Cr, Nb, Ba, Ti, Zr etc. indicates, similar to parent kimberlite/lamproite rock, favourable targets for further ground exploration in virgin areas present study, two samples, towards five kilometers northeast of Vattikodu Lamproite Field, possess higher concentrations of Nb (>25ppm), Ba (>400 ppm), Zr (>650 ppm) and Ti (>3500 ppm) which stand out as plausible explorable targets for further ground investigations. Further investigations on these two locations are suggested to ascertain whether or not these two targets unveil new kimberlites/lamproite occurrences in the area.
DS201907-1569
2019
Phani, R.Phani, R., Srinivas, M.Role of calcrete petrography in reconnaissance kimberlite exploration - some evidence from Wajkakarur field, Anantapur district, Andhra Pradesh.Science Spectrum, Vol. 3, 3-4, pp. 44-56. pdfIndiadeposit - Wajrakarur
DS202007-1170
2020
Phani, R.Phani, R., Sengupta, P., Basu, S.Geochemistry and petrology of two kimberlites at Krishtipadu from Gooty cluster, Andhra Pradesh, southern India - evidence of kimberlite magmatism and a possible carbonate association within Paleoproterozoic lower Cuddapah Basin.Russian Journal of Earth Sciences, Vol. 20, ES3006 14p. PdfIndia, Andhra Pradeshdeposit - Kristipadu

Abstract: This paper addresses geochemical and petrological aspects of two outcropping kimberlites (5023 and 5119) of the Gooty cluster, emplaced in carbonate sediments of Vempalli Formation of lower Cuddapah basin at Krishtipadu, Anantapur district, Andhra Pradesh, southern India. These pipes were discovered by the Rio Tinto Exploration Group in the recent past. The 5023 kimberlite is enriched in olivine and serpentine while the 5119 pipe possesses haematitised olivine pseudomorphs. The field, textural characteristics and whole rock geochemistry qualify both the pipes for hypabyssal kimberlite breccias of Group-I type similar to world’s classical occurrences. The carbon and oxygen stable isotope data, aided with field and petrological studies, indicates existence of possible carbonatite (sovite) phase associated with the 5119 kimberlite. The two kimberlites appear to be originated from a low degree of partial melting ranging from 0.5 to 2.5%. Enrichment of LREE with a high LREE/HREE ratio indicates fractionation at the mantle source region. Whole rock geochemistry supports their diamondiferous nature. Presence of crustal xenoliths post-dates subsequent emplacement of the two pipes to lower Cuddapah sedimentation (2.4 Ga), manifesting kimberlite magmatism. These pipes are the only known Group-I kimberlites from the Proterozoic Cuddapah Basin and therefore warrant detailed investigations. KEYWORDS: Kimberlite; carbonatite; archetypal Group-I; Gooty Kimberlite Cluster; lower Cuddapah basin; stable isotope; Palaeoproterozoic.
DS2002-1719
2002
Pharaoh, T.C.Winchester, J.A., Pharaoh, T.C.Paleozoic amalgamation of central EuropeGeological Society of London (U.K.), 352p.$ 142.00 http://bookshop.geolsoc.org.ukEuropeBook - terranes
DS200712-0840
2006
Pharaoh, T.C.Pharaoh, T.C., Winchester, J.A., Verniers, J., Lassen, A., Seghedi, A.The Western accretionary margin of the East European Craton: an overview.Geological Society of London Memoir, No. 32, pp. 291-312.Russia, Europe, UralsCraton
DS1950-0419
1958
Phaup, A.E.Phaup, A.E.Notes on the Kimberlite Bodies in Southern RhodesiaGeological Survey Southern Rhodesia., (UNPUBL.)ZimbabweGeology
DS200412-1539
2004
Phelps, D.Phelps, D.It's a blast like an Antwerp cutter assessing a rough diamond, drilling and blasting has almost infinite possibilities.Mining Magazine, Jan. pp. 17-32.TechnologyMining - drilling technology not specific to diamonds
DS1993-1230
1993
Phelps, R.W.Phelps, R.W.Money - where is mine finance going?Engineering and Mining Journal, Vol. 194, No. 8, August p. 24-29GlobalEconomics, World, Mine financing
DS2001-0915
2001
Phelps, R.W.Phelps, R.W.More than reindeer and lingonberries... resurgence of geological activity... two pages on diamonds.Engineering and Mining Journal, Vol. 202, No. 2, Feb. pp. www34-9.SwedenNews item, Alcaston Diamond
DS1990-1179
1990
Phelps, S.Phelps, S.Copeton is a diamond miner's best friendAustralian Min, Vol. 82, No. 5, May pp. 22-26AustraliaNews item, Cluff Resources, industrial
DS1993-1231
1993
Phil. Transactions Royal Society of LondonPhil. Transactions Royal Society of LondonThin film diamond... a discussion and conference organized and edited byA.H. Lettington and J.W. Steeds. Table of contents available.Philosphical Transactions Royal Society of London, Section A Vol. 342, No. 1664, Feb. 15, pp. 193-322.GlobalCVD., Diamond filM.
DS200912-0586
2009
Philander, S.G.Philander, S.G.Where are you from? Why are you here? An African perspective on global warming.Annual Review of Earth and Planetary Sciences, Vol. 37, pp. 1-18.TechnologyGlobal warming
DS1998-0514
1998
PhilipGirnis, A.V., Stachel, T., Brey, G., Harris, J., PhilipInternally consistent geothermobarometers for garnet harzburgites7th International Kimberlite Conference Abstract, pp. 253-5.GlobalGeothermometry, Garnet harzburgite compositions
DS1989-1208
1989
Philip, G.M.Philip, G.M., Watson, D.F.Some geometric aspects of the ternary diagraMJournal of Geological Education, Vol. 37, No. 1, January pp. 27-30GlobalMineralogy
DS1989-1584
1989
Philip, G.M.Watson, D.F., Philip, G.M.Measures of variability for geological dataMathematical Geology, Vol. 21, No. 2, February pp. 233-254. Database # 17780GlobalGeostatistics, Variability
DS1993-0948
1993
PhilipeMachado, N., David, Scott, Lamothe, Philipe, Gariepyuranium-lead (U-Pb) geochronology of the western Cape Smith Belt: new insights on age of initial rifting and arc magmatismGeological Association of Canada (GAC), Annual Meeting, Vol. 16, p. A78. abstract.Quebec, Ungava, LabradorGeochronology, Tectonics
DS200812-1012
2007
Philippe, M.Scalie, S., Philippe, M., Sirakian, D.La mine de Williamson.Revue de gemologie, No. 159, pp. 21-25. in French.Africa, TanzaniaHistory
DS1993-1232
1993
Philippe, S.Philippe, S., Wardle., R.J., Scharer, U.Labradorian and Grenvillian crustal evolution of the Goose Bay region, Labrador and geochronological...Canadian Journal of Earth Sciences, Vol. 30, pp. 2315-2.Labrador, QuebecGeochronology
DS201805-0967
2007
Philippips, D.O'Brien, H., Philippips, D., Spencer, R.Isotopic ages of Lentiira-Kuhmo-Kostomuksha olivine lamproite - Group II kimberlites NOTE Date of publ. Bulletin of the Geological Survey of Finland, Vol. 79, 2, pp. 203-215.Europe, Finlanddeposit - Lentiira Kuhmo

Abstract: The Lentiira-Kuhmo-Kostomuksha triangle, along the Finland - Russian border and within the central part of the Archean Karelian craton, contains numerous examples of phlogopite-rich, ultramafic, mantle-xenocryst-bearing and, in some cases, diamond-bearing dike rocks. Laser probe Ar-Ar data on phlogopite from 3 dike rocks on the Finnish side (Lentiira, Kuhmo) all gave ages within error of each other, 1202 ± 3 Ma (2?), 1199 ± 3 Ma (2?) and 1204 ± 4 Ma (2?) while a fourth sample produced mixed ages. Published Rb-Sr dates on mineralogically and chemically similar dikes from the Russian side (Kostomuksha) are 1232 ± 5 Ma. The question remains open whether these represent two distinct age populations or whether differences in isotopic system behavior are the reason for the 30 m.y. age difference.
DS1991-1344
1991
Philippot, P.Philippot, P., Selverstone, J.Trace element rich brines in eclogitic veins: implications for fluid composition and transport during subductionContributions to Mineralogy and Petrology, Vol. 417-430GlobalOphiolites, Brines -fluid inclusions -subduction
DS1992-1192
1992
Philippot, P.Philippot, P., Van Roermund, H.L.M.Deformation processes in eclogitic rocks: evidence for the rheological delamination of the oceanic crust in deeper levels of subduction zones.Journal of Structural Geology, Vol. 14, No. 89, pp. 1059-1077.GlobalEclogites, Crust
DS1993-1106
1993
Philippot, P.Nadeau, S., Philippot, P., Pineau, F.Fluid inclusion and mineral isotopic compositions (H-C-O) in eclogitic rocks as tracers of local fluid migration during high pressure metamorphismEarth and Planetary Science Letters, Vol. 114, pp. 431-448.GlobalEclogite, Geochronology
DS1993-1233
1993
Philippot, P.Philippot, P.Fluid melt rock interaction in mafic eclogites and coesite bearingmetasediments: constraints on volatile recycling during subduction.Chemical Geology, Vol. 108, No. 1-4, August 5, pp. 93-112.MantleSubduction, Eclogites
DS2000-0753
2000
Philippot, P.Perchuk, A.L., Philippot, P.Geospeedometry and time scales of high pressure metamorphismInternational Geology Review, Vol. 42, No. 3, March pp. 207-223.Globalultra high pressure (UHP)
DS2000-0762
2000
Philippot, P.Philippot, P., Rumble III, D.Fluid rock interactions during high pressure and ultrahigh pressure metamorphism.International Geology Review, Vol. 42, No. 4, Apr 1, pp. 312-327.Mantlemetamorphism
DS2001-0916
2001
Philippot, P.Philippot, P., Blichertoft, Perchuk, Costa, GerasimovLutetium(Lu)- Hafnium(Hf) and Argon- Argon chronology supports extreme rate of subduction zone metamorphism deduced geospeedometryTectonophysics, Vol. 342, No. 2, pp. 23-38.MantleGeochronology, Argon, Lutetium, Hafnium, Subduction
DS2001-1024
2001
Philippot, P.Scambelluri, M., Philippot, P.Deep fluids in subduction zonesLithos, Vol. 55, No.1-4, Jan. pp. 213-27.MantleSubduction, eclogite, metamorphism, Fluid inclusions
DS2003-1159
2003
Philippot, P.Rey, P.F., Philippot, P., Thebaud, N.Contribution of mantle plumes, crustal thickening and greenstone blanketing to the 2.75Precambrian Research, Vol. 127, 1-2, Nov. pp. 43-60.MantleHot spots, tectonics
DS200412-1659
2003
Philippot, P.Rey, P.F., Philippot, P., Thebaud, N.Contribution of mantle plumes, crustal thickening and greenstone blanketing to the 2.75 - 2.65 Ga global crisis.Precambrian Research, Vol. 127, 1-2, Nov. pp. 43-60.MantleHotspots, tectonics
DS200612-0386
2005
Philippot, P.Famin, V., Herbert, R., Philippot, P., Jolivet, L.Ion probe and fluid inclusions evidence for co-seismic fluid infiltration in a crustal detachment.Contributions to Mineralogy and Petrology, Vol. 150, 3, pp. 354-367.MantleGeochronology
DS201312-0275
2013
Philippot, P.Francois, C., Philippot, P., Rey, P., Rubatto, D., Moyen, J-F.Archean geodynamic: fingerprinting sagduction vs subduction processes.Goldschmidt 2013, AbstractMantleSagduction
DS201312-0581
2013
Philippot, P.Marty, B., Zimmermann, L., Pujol, M., Burgess, R., Philippot, P.Nitrogen isotopic composition and density of the Archean atmosphere.Science, Vol. 342, 6154, pp. 101-104.MantleVolatiles
DS201808-1724
2018
Philippot, P.Avice, G., Marty, B., Burgess, R., Hofmann, A., Philippot, P., Zahnle, K., Zakharov, D.Evolution of atmospheric xenon and other noble gases inferred from Archean to Paleoproterozoic rocks.Geochimica et Cosmochimica Acta, Vol. 232, pp. 82-100.Mantlegeochemistry

Abstract: We have analyzed ancient atmospheric gases trapped in fluid inclusions contained in minerals of Archean (3.3?Ga) to Paleozoic (404?Ma) rocks in an attempt to document the evolution of the elemental composition and isotopic signature of the atmosphere with time. Doing so, we aimed at understanding how physical and chemical processes acted over geological time to shape the modern atmosphere. Modern atmospheric xenon is enriched in heavy isotopes by 30-40‰ u?1 relative to Solar or Chondritic xenon. Previous studies demonstrated that, 3.3?Ga ago, atmospheric xenon was isotopically fractionated (enriched in the light isotopes) relative to the modern atmosphere, by 12.9?±?1.2 (1?) ‰ u?1, whereas krypton was isotopically identical to modern atmospheric Kr. Details about the specific and progressive isotopic fractionation of Xe during the Archean, originally proposed by Pujol et al. (2011), are now well established by this work. Xe isotope fractionation has evolved from 21‰ u?1 at 3.5?Ga to 12.9‰ u?1 at 3.3?Ga. The current dataset provides some evidence for stabilization of the Xe fractionation between 3.3 and 2.7?Ga. However, further studies will be needed to confirm this observation. After 2.7?Ga, the composition kept evolving and reach the modern-like atmospheric Xe composition at around 2.1?Ga ago. Xenon may be the second atmospheric element, after sulfur, to show a secular isotope evolution during the Archean that ended shortly after the Archean-Proterozoic transition. Fractionation of xenon indicates that xenon escaped from Earth, probably as an ion, and that Xe escape stopped when the atmosphere became oxygen-rich. We speculate that the Xe escape was enabled by a vigorous hydrogen escape on the early anoxic Earth. Organic hazes, scavenging isotopically heavy Xe, could also have played a role in the evolution of atmospheric Xe. For 3.3?Ga-old samples, Ar-N2 correlations are consistent with a partial pressure of nitrogen (pN2) in the Archean atmosphere similar to, or lower than, the modern one, thus requiring other processes than a high pN2 to keep the Earth's surface warm despite a fainter Sun. The nitrogen isotope composition of the atmosphere at 3.3?Ga was already modern-like, attesting to inefficient nitrogen escape to space since that time.
DS1987-0580
1987
Philippov, N.D.Philippov, N.D.Manganiferous crichtonite in kimberlite breccias. (Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 296, No. 6, pp. 1462-1465RussiaBlank
DS200812-0860
2007
Philipps, D.Paton, C., Woodhead, J.D., Hergt, J.M., Philipps, D.,Shee, S.Strontium isotope analysis of kimberlitic groundmass perovskite via La-MC-ICP-MS.Geostandards and Geoanalytical Research, in press availableTechnologyGeochronology
DS1989-1209
1989
Philips, D.Philips, D., Onstott, T.C., Harris, J.W.40Ar/39Ar laser-probe dating of diamond inclusions from the PremierkimberliteNature, Vol. 30, No. 6233, August 10, pp. 460-462South AfricaDiamond morphology, Diamond inclusions
DS201910-2308
2019
Philips, D.Woodhead, J., Hergt, J., Giuliani, A., Maas, R., Philips, D., Pearson, D.G., Nowell, G.Kimberlites reveal 2.5-nillion year evolution of a deep, isolated mantle reservoir.Nature, Vol. 573, pp. 578-581.Mantlemelting

Abstract: The widely accepted paradigm of Earth's geochemical evolution states that the successive extraction of melts from the mantle over the past 4.5 billion years formed the continental crust, and produced at least one complementary melt-depleted reservoir that is now recognized as the upper-mantle source of mid-ocean-ridge basalts1. However, geochemical modelling and the occurrence of high 3He/4He (that is, primordial) signatures in some volcanic rocks suggest that volumes of relatively undifferentiated mantle may reside in deeper, isolated regions2. Some basalts from large igneous provinces may provide temporally restricted glimpses of the most primitive parts of the mantle3,4, but key questions regarding the longevity of such sources on planetary timescales—and whether any survive today—remain unresolved. Kimberlites, small-volume volcanic rocks that are the source of most diamonds, offer rare insights into aspects of the composition of the Earth’s deep mantle. The radiogenic isotope ratios of kimberlites of different ages enable us to map the evolution of this domain through time. Here we show that globally distributed kimberlites originate from a single homogeneous reservoir with an isotopic composition that is indicative of a uniform and pristine mantle source, which evolved in isolation over at least 2.5 billion years of Earth history—to our knowledge, the only such reservoir that has been identified to date. Around 200 million years ago, extensive volumes of the same source were perturbed, probably as a result of contamination by exogenic material. The distribution of affected kimberlites suggests that this event may be related to subduction along the margin of the Pangaea supercontinent. These results reveal a long-lived and globally extensive mantle reservoir that underwent subsequent disruption, possibly heralding a marked change to large-scale mantle-mixing regimes. These processes may explain why uncontaminated primordial mantle is so difficult to identify in recent mantle-derived melts.
DS1991-1481
1991
PhillipeRyan, B., Krogh, T.E., Heaman, Scharer, PhillipeOn recent geochronological studies in the Nain Province Churchill province and Plutonic Suite.Newfound. Geological Survey, Paper 91-1, pp. 257-61.Quebec, Labrador, UngavaNain Plutonic suite, Geochronology
DS1997-1257
1997
Phillipo, S.Williams, C.T., Wall, F., Woolley, A.R., Phillipo, S.Compositional variation in pyrochlore from the Bingo carbonatite, ZaireJournal of African Earth Sciences, Vol. 25, No. 1, July pp. 137-146.Democratic Republic of CongoCarbonatite
DS1995-1493
1995
Phillipot, P.Phillipot, P.Fluid composition and evolution in coesite bearing rocks Dora Maire Massif:recycling during subduction.Contributions to Mineralogy and Petrology, Vol. 121, No. 1, pp. 29-44.GlobalCoesite, Subduction
DS1998-0778
1998
Phillipov, N. Zauzev.Komilova, V.P., Safronov, A.F., Phillipov, N. Zauzev.The garnet of diamond association in lamprophyres from the Anabar massif7th International Kimberlite Conference Abstract, pp. 458-9.Russia, Yakutia, AnabarDiamond inclusions, Lamprophyres
DS1998-1271
1998
PhillipsRyan, B., Phillips, Shwetz, MachadoA tale of more than ten plutons - Okay Bay and Staghorn lakeNewfound. Geological Survey, Paper 98-1, pp. 143-71.Quebec, Labrador, UngavaAnorthosites
DS201012-0583
2010
PhillipsPhillipsGeochronological constraints on the perseverance of gemstone placer deposits: examples from detrital diamond deposits.13th. IAGOD Symposium, April 6-9, Adelaide Australia, Alluvials, deposits
DS200512-0852
2005
Phillips, B.R.Phillips, B.R., Bunge, H-P.Heterogeneity and time dependence in 3D spherical mantle convection models with continental drift.Earth and Planetary Science Letters, Vol. 233, 1-2, April 30, pp. 121-135.Mantle, Asia, AntarcticaWilson cycle, convection, supercontinents
DS200712-0841
2007
Phillips, B.R.Phillips, B.R., Bunge, H.P.Supercontinent cycles disrupted by strong mantle plumes.Geology, Vol. 35, 9. pp. 847-850.MantleAccretion
DS200712-0842
2007
Phillips, B.R.Phillips, B.R., Coltice, N., Bertrand, H., Ricard, Y., Rey, P.Supercontinental warming, plumes and mantle evolution.Plates, Plumes, and Paradigms, 1p. abstract p. A786.MantleMagmatism
DS200912-0587
2009
Phillips, B.R.Phillips, B.R., Bunge, H-P., Schaber, K.True polar wander in mantle convection models with multiple, mobile continents.Gondwana Research, Vol. 15, 3-4, pp. 288-196.MantleConvection
DS1985-0527
1985
Phillips, D.Phillips, D., Onstott, T.C.Mantle Derived Argon Components in Phlogopite from Southern african Kimberlites.Geological Society of America (GSA), Vol. 17, No. 7, P. 688. (abstract.).South AfricaGeochronology
DS1986-0641
1986
Phillips, D.Phillips, D., Onstott, T.C.Application of Argon 36/Argon 40 versus Argon 39/Argon 40correlation To the Argon 40/Argon 39 spectra of phlogopites from Southern African kimberlitesGeophysical Research Letters, Vol. 13, No. 7, July pp. 689-692BotswanaGeochronology
DS1986-0642
1986
Phillips, D.Phillips, D., Onstott, T.C.Mantle derived argon components in phlogopite from southernAfricankimberlitesProceedings of the Fourth International Kimberlite Conference, Held Perth, Australia, No. 16, pp. 306-308South AfricaBlank
DS1988-0543
1988
Phillips, D.Phillips, D., Onstott, T.C.Argon isotopic zoning in mantle phlogopiteGeology, Vol. 16, No. 6, June pp. 542-546South AfricaPremier
DS1989-1210
1989
Phillips, D.Phillips, D.Argon isotopic studies of minerals in kimberlites,mantle xenoliths anddiamonds, from selected Southern african localitiesPh.D. Thesis, Princeton Univ, 280pSouth AfricaGeochronology, Mantle xenoliths, diamonds
DS1991-1345
1991
Phillips, D.Phillips, D.Argon isotope and halogen chemistry of phlogopite from South Africankimberlites: a combined step-heating, laser probe, electron microprobe and TEMstudyChem. Geology, Vol. 87, pp. 71-98South AfricaGeochemistry, Swartruggens
DS1995-1494
1995
Phillips, D.Phillips, D., Harris, J.W.Geothermobarometry of diamond inclusions from the de Beers Pool Mines, Kimberley, South Africa.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 441-442.South AfricaGeothermbarometry, Deposit -De Beers Pool Mines
DS1998-0188
1998
Phillips, D.Burgess, R., Phillips, D., Harris, J.W., Robinson, D.N.Antarctic diamonds in south eastern Australia? Hints from 40 Ar-39AR laser probe dating of clinopyroxene..7th International Kimberlite Conference Abstract, pp. 119-121.Australia, AntarcticaAlluvials, Argon, Deposit - Copeton
DS1998-0760
1998
Phillips, D.Kiviets, G., Phillips, D., Shee, S.R., Vercoe, S.C.40 Ar-39 Ar dating of yimengite from the Turkey Well kimberlite, Australia: the oldest and the rarest.7th International Kimberlite Conference Abstract, pp. 432-34.AustraliaGeochronology, Argon, Deposit - Turkey Wells, Leonora area
DS1998-1158
1998
Phillips, D.Phillips, D., Harris, J.W., Kiviets, Burgess, Fourie40 Ar39 Laser probe analyses of clinopyroxene diamond inclusions from the Orapa and Mbuyi Miya Mines.7th. Kimberlite Conference abstract, pp. 687-9.GlobalGeochronology, diamond inclusions, Deposit - Orapa, Mbuyi Miya
DS1998-1159
1998
Phillips, D.Phillips, D., Kiviets, Barton, Smith, Viljoen, Fourie40 Ar39 dating of kimberlites and related rocks: problems and solutions7th. Kimberlite Conference abstract, pp. 690-2.South Africa, Botswana, ZimbabweGeochronology, Deposit - Venetia, Oaks, Colorssus, Lace, Rex, Pniel
DS1998-1160
1998
Phillips, D.Phillips, D., Machin, K.J., Skinner, E.M.W.A petrographic and 40 Ar-39 Ar geochronological study of the Voorspoedkimberlite, implications for origin..South African Journal of Geology, Vol. 101, No. 4, Dec. 1, pp. 299-306.South AfricaKimberlite - Group II magmatism, Deposit - Voorspoed, Argon
DS1998-1545
1998
Phillips, D.Viljoen, K.S., Phillips, D., Harris, J.W., Robinson, D.Mineral inclusions in diamonds from the Venetia kimberlites, NorthernProvince, South Africa.7th International Kimberlite Conference Abstract, pp. 943-5.South AfricaDiamond morphology - garnet inclusions, Deposit - Venetia
DS1999-0555
1999
Phillips, D.Phillips, D., Kiviets, Barton, Smith, Viljoen, Fournie40 Ar-39 Ar dating of kimberlites and related rocks, problems and solutions.7th International Kimberlite Conference Nixon, Vol. 2, pp. 677-88.South Africa, Zimbabwe, Barkly WestGeochronology, argon, Venetia, Colossus, Postmas, Pniel, Marnitz, Rex, Lace
DS1999-0772
1999
Phillips, D.Viljoen, K.S., Phillips, D., Harris, J.W., Robinson, D.Mineral inclusions in diamonds from the Venetia kimberlites, Northern Province, South Africa.7th International Kimberlite Conference Nixon, Vol. 2, pp. 888-95.South AfricaDiamond - inclusions, mineral chemistry, Deposit - Venetia
DS2000-0763
2000
Phillips, D.Phillips, D., Kiviets, G.B., Armstrong, R.A.Geochronology of kimberlites and related rocks: a synthesis of available radiometric techniques.Geological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) 2000, 3p. abstract.Australia, South AfricaGeochronology - age determinations, Methodology
DS2003-0662
2003
Phillips, D.Johnson, L.H., Phillips, D.40 Ar 40 Ar dating of mantle metasomatism: a noble approach or all hot air?8ikc, Www.venuewest.com/8ikc/program.htm, Session 4, POSTER abstractSouth AfricaMantle geochemistry, Deposit - Kimberley, geochronology
DS2003-1074
2003
Phillips, D.Phillips, D., Harris, J.W.The effect of differential mineral compressibility on diamond inclusion thermobarometry8 Ikc Www.venuewest.com/8ikc/program.htm, Session 3, AbstractSouth AfricaDiamonds - geothermobarometry, Deposit - Kimberley Pool
DS200412-0847
2004
Phillips, D.Honda, M., Phillips, D., Harris, J.W., Yatsevich, I.Unusual noble gas compositions in polycrystalline diamonds: preliminary results from the Jwaneng kimberlite, Botswana.Chemical Geology, Vol. 203, 3-4, Feb. 16, pp. 347-358.Africa, BotswanaMantle evolution, lithosphere, geochemistry
DS200412-1540
2003
Phillips, D.Phillips, D., Harris, J.W.The effect of differential mineral compressibility on diamond inclusion thermobarometry.8 IKC Program, Session 3, AbstractAfrica, South AfricaDiamonds - geothermobarometry Deposit - Kimberley Pool
DS200412-1541
2004
Phillips, D.Phillips, D., Harris, J.W., Kiviets, G.B.40 Ar 39 Ar analyses of clinopyroxene inclusions in African diamonds: implications for source ages of detrital diamonds.Geochimica et Cosmochimica Acta, Vol. 68, 1, pp. 151-165.Africa, Democratic Republic of Congo, Botswana, South AfricaMbuji-Mayi, Jwaneng, Orapa, Premier
DS200412-1542
2004
Phillips, D.Phillips, D., Harris, J.W., Viljoen, K.S.Mineral chemistry and thermobarometry of inclusions from De Beers Pool diamonds, Kimberley, South Africa.Lithos, Vol. 77, 1-4, Sept. pp. 155-179.Africa, South AfricaDiamond Inclusions, silicate, oxide, harzburgitic
DS200612-1048
2006
Phillips, D.Paton, C., Hergt, J.M., Woodhead, J.D., Phillips, D.Laser ablation analysis of DR isotopes in kimberlitic perovskite.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 10. abstract only.AustraliaGeochronology
DS200712-0818
2007
Phillips, D.Paton, C., Hergt, J.M., Phillips, D., Woodhead, J.D., Shee, S.R.New insights into the genesis of Indian kimberlites from the Dharwat Craton via in situ SR isotope analysis of groundmass perovskite.Geology, Vol. 35, 11, pp. 1011-1014.IndiaGeochronology
DS200812-0859
2008
Phillips, D.Paton, C., Hergt, J.M., Phillips, D., Woodhead, J.D., Shee, S.R.Identifying the asthenospheric component of kimberlite magmas from the Dharwar craton, India.9IKC.com, 3p. extended abstractIndiaDeposit - Narayanpet, Wajakarur
DS200812-0893
2008
Phillips, D.Phillips, D., Harris, J.W.Provenance studies from 40 Ar 39 Ar dating of mineral inclusions in diamonds: methodological tests on the Orapa kimberlite, Botswana.Earth and Planetary Science Letters, Vol. 274, 1-2, pp. 169-178.Africa, BotswanaDeposit - Orapa
DS200812-0974
2008
Phillips, D.Rossetti, F., Cozzupoli, D., Phillips, D.Compressional reworking of the East African Orogen in the Uluguru Mountains of eastern Tanzania at c. 550Ma: implications for the final assembly of Gondwana.Terra Nova, Vol. 20, 1, pp. 59-67.Africa, TanzaniaTectonics
DS200812-1264
2008
Phillips, D.Woodhead, J.D., Phillips, D., Hergt, J., Paton, C.African kimberlites revisited: in situ Sr isotope analysis of groundmass perovskite.Goldschmidt Conference 2008, Abstract p.A1035.Africa, South AfricaGeochronology
DS200812-1265
2008
Phillips, D.Woodhead, J.D., Phillips, D., Hergt, J.M., Paton, C.African kimberlites revisited: in situ Sr isotope analysis of groundmass perovskite.9IKC.com, 2p. extended abstractAfrica, South AfricaGroup I and II
DS200912-0031
2009
Phillips, D.Banas, A., Stachel, T., Phillips, D., Shimizu, N., Viljoen, K.S., Harris, J.W.Ancient metasomatism recorded by ultra-depleted garnet inclusions in diamonds from De Beers Pool, South Africa.Lithos, In press availableAfrica, South AfricaDeposit - DeBeers Pool
DS200912-0113
2008
Phillips, D.Chesler, R., Hergt, J., Phillips, D., Maas, R.The geochemistry of the West Australian, West Kimberley province lamproites.Geological Society of Australia Abstracts, Vol. 90, p. 35. abs.AustraliaLamproite
DS200912-0352
2009
Phillips, D.Kamenetsky, V.S., Mass, R., Kamenetsky, M.B., Paton, C., Phillips, D., Golovin, A.V., Gornova, M.A.Chlorine from the mantle: magmatic halides in the Udachnaya-East kimberlite, Siberia.Earth and Planetary Science Letters, Vol. 285, pp. 96-104.Russia, SiberiaDeposit - Udachnaya
DS200912-0422
2009
Phillips, D.Laiginhas, F., Pearson, D.G., Phillips, D., Burgess, R., Harris, J.W.Re Os and 40Ar 39Ar isotope measurements of inclusions in alluvial diamonds from the Ural Mountains: constraints on diamond genesis and eruption ages.Lithos, in press availableRussia, UralsGeochronology
DS200912-0479
2009
Phillips, D.Matchan, E., Hergt, J., Phillips, D., Shee, S.The geochemistry, petrogenesis and age of an unusual alkaline intrusion in the western Pilbara craton, western Australia.Lithos, In press availableAustraliaGeochronology
DS200912-0480
2008
Phillips, D.Matchan, E., Hergt, J., Phillips, D., Shee, S.The age, geochemistry and petrogenesis of an unusual alkaline intrusion in the western Pilbara, western Australia.Geological Society of Australia Abstracts, Vol. 90, p. 36. abs.AustraliaAlkalic
DS200912-0573
2009
Phillips, D.Paton, C., Hergt, J.M., Woodhead, J.D., Phillips, D., Shee, S.R.Identifying the asthenosphere component of kimberlite magmas from the Dharwar Craton, India.Lithos, in press availableIndiaChemistry
DS200912-0588
2009
Phillips, D.Phillips, D., Harris, J.W.Diamond provenance studies from 40 Ar 39 Ar dating of clinopyroxene inclusions: an example from the west coast of Namibia.Lithos, In press availableAfrica, NamibiaGeochronology
DS201012-0284
2010
Phillips, D.Honda, M., Phillips, D., Harris, J., Matsumoto, T.Distinct neon isotope compositions found in polycrystalline diamonds and framesites from the Jwaneng kimberlite pipe, Botswana.Goldschmidt 2010 abstracts, abstractAfrica, BotswanaGeochronology
DS201012-0858
2009
Phillips, D.Woodhead, J., Hergt, J., Phillips, D., Paton, C.African kimberlites revisited: in situ Sr isotope analysis of groundmass perovskite.Lithos, Vol. 112 S pp. 311-317.AfricaKaapvaal craton deposits
DS201112-0447
2011
Phillips, D.Honda, M., Phillips, D., Harris, J.W., Matsumoto, T.He, Ne and Ar in peridotitic and eclogitic paragenesis diamonds from the Jwaneng kimberlite, Botswana - implications for mantle evolution and diamond formation ages.Earth and Planetary Science Letters, Vol. 301, 1-2, pp. 43-51.Africa, BotswanaGeocheonology - Jwaneng
DS201112-0495
2011
Phillips, D.Kamenetsky, V.S., Mass, R., Kamenetsky, M.B., Paton, C., Phillips, D., Golovin, A.V.Chlorine from the mantle: magmatic halides in the Udachnaya East kimberlite, Siberia.Deep Seated Magmatism, its sources and plumes, Ed. Vladykin, N.V., pp. 132-149.Russia, SiberiaModel magma compositions
DS201212-0128
2012
Phillips, D.Chesler, R., Hergt, J., Woodhead, J., Phillips, D.Geochemistry and geochronology of Tanzanian kimberlites,10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractAfrica, TanzaniaGroup 1 kimberlites
DS201212-0199
2012
Phillips, D.Felgate, M., Hergt, J., Phillips, D., Woodhead, J.The Brazilian kimberlite-kamafugite association: a new and improved geochronological and geochemical investigation.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractSouth America, BrazilRondonia, Mato Grosso, Gias, Minas Gerais samples
DS201212-0243
2012
Phillips, D.Giulani, A., Kamenetsky, V.S., Phillips, D., Wyatt, B.A., Hutchinson, G.Alkali-carbonate fluids in the lithospheric mantle.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractMantleCarbonatite
DS201212-0244
2012
Phillips, D.Giuliani, A., Kamenetsky, V.S., Kendrick, M.A., Phillips, D., Goemann, K.Nickel rich metasomatism of the lithospheric mantle by pre-kimberlitic alkali S Cl rich C-O-H fluids.Contributions to Mineralogy and Petrology, in press availableAfrica, South AfricaDeposit - Bultfontein
DS201212-0245
2012
Phillips, D.Giuliani, A., Kamenetsky, V.S., Phillips, D., Kendrick, M.A., Wyatt, B.A., Goemann, K.Nature of alkali-carbonate fluids in the sub-continental lithospheric mantle.Geology, Vol. 40, 11, pp. 967-970.Mantle, RussiaDeposit - Udachnaya
DS201212-0246
2012
Phillips, D.Giuliani, A.,Kamenetsky, V.S., Lendrick, M.A., Phillips, D., Goemann, K.Nickel-rich metasomatism of the lithospheric mantle by pre-kimberlitic alkali-S-Cl-rich C-O-H fluids.Contributions to Mineralogy and Petrology, in press available 17p.MantleMetasomatism
DS201212-0269
2012
Phillips, D.Guilani, A., Kendrick, M.A., Phillips, D.Halogen and AR geochemistry of metasomatic mantle xenoliths from the Bultfontein pipe (Kimberley district, South Africa).10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractAfrica, South AfricaDeposit - Bultfontein
DS201212-0339
2012
Phillips, D.Jelsma, H.,Krishnan, S.U., Perritt, S.,Kumar, M., Preston, R., Winter, F., Lemotlo, L., Costa, J., Van der Linde, G., Facatino, M., Posser, A., Wallace, C., Henning, A., Joy, S., Chinn, I., Armstrong, R., Phillips, D.Kimberlites from central Angola: a case stidy of exploration findings.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractAfrica, AngolaOverview of kimberlites
DS201212-0552
2012
Phillips, D.Phillips, D., Clarke, W., Jaques, A.L.New Ar40/39Ar ages for the West Kimberley lamproites and implications for Australian plate geodynamics.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractAustraliaGeochronology
DS201212-0553
2012
Phillips, D.Phillips, D., Giullani, A., Jelsma, H., Joy, S.40Ar/39AR analyses of kelphite: a new approach for dating kimberlites and related rocks.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractAfrica, South Africa, AngolaDeposit Dando Kwanza
DS201212-0555
2012
Phillips, D.Phillips,D.Comment on New Ar-Ar ages of southern Indian kimberlites ……Precambrian Research, Vol. 208-211, pp. 49-52.IndiaGeochronology
DS201312-0313
2013
Phillips, D.Giuliani, A., Kamenetsky, V.S., Kendrick, M.A., Phillips, D., Wyatt, B.A., Maas, R.Oxide, sulphide and carbonate minerals in a mantle polymict breccia: metasomatism by proto-kimberlite magmas, and relationship to the kimberlite megacrystic suite.Chemical Geology, Vol. 353, pp. 4-18.Africa, South AfricaKimberley district
DS201312-0314
2013
Phillips, D.Giuliani, A., Phillips, D., Kendrick, M.K., Maas, R., Greig, A., Armstrong, R., Felgate, M.R., Kamenetsky, V.S.Dating mantle metasomatism: a new tool ( U/PB LIMA Titanate) and an imposter ( 40Ar/39Ar phlogopite).Goldschmidt 2013, AbstractMantleMetasomatism
DS201312-0344
2013
Phillips, D.Guiliani, A., Phillips, D., Fiorentini, M.L., Kendrick, M.A., Maas, R., Wing, B.A., Woodhead, J.D., Bui, T.H., Kamenetsky, V.S.Mantle oddities: a sulphate fluid preserved in a MARID xenolith from the Bultfontein kimberlite ( Kimberley South Africa).Earth and Planetary Science Letters, Vol. 376, pp. 74-86.Africa, South AfricaDeposit - Bultfontein
DS201312-0400
2012
Phillips, D.Honda, M., Phillips, D., Kendrick, M.A., Gagan, M.K., Taylor, W.R.Noble gas and carbon isotope ratios in Argyle diamonds, western Australia: evidence for a deeply subducted volatile component.Australian Journal of Earth Sciences, Vol. 59, 8, pp. 1135-1142.AustraliaDeposit - Argyle
DS201412-0293
2014
Phillips, D.Giuliani, A., Phillips, D., Kamenetsky, V.S., Fiorentini, M.L., Farqukar, J., Kendrick, M.A.Stable isotope ( C,O,S) compositions of volatile rich minerals in kimberlites: a review.Chemical Geology, Vol. 374-375, pp. 61-83.Africa, South Africa, Canada, Northwest Territories, RussiaDeposit - Kimberley, Lac de Gras, Udachnaya
DS201412-0294
2014
Phillips, D.Giuliani, A., Phillips, D., Kamenetsky, V.S., Kendrick, M.A., Wyatt, B.A., Goemann, K., Hutchinson, G.Petrogenesis of mantle polymict breccias: insights into mantle processes coeval with kimberlite magmatism.Journal of Petrology, Vol. 55, 4, pp. 831-858.Africa, South AfricaDeposit - Bultfontein
DS201412-0296
2014
Phillips, D.Giuliani, G., Phillips, D., Maas, R., Woodhead, J.D., Kendrick, M.A., Greig, A., Armstrong, R.A., Chew, D., Kamenetsky, V.S., Fiorentini, M.I.LIMA U-Pb ages link lithospheric mantle metasomatism to Karoo magmatism beneath the Kimberley region, South Africa.Earth and Planetary Science Letters, Vol. 401, pp. 132-147.Africa, South AfricaKimberlite
DS201412-0427
2013
Phillips, D.Jelsma, H., Krishnan, U., Perritt, S., Preston, R., Winter, F., Lemotlo, L., van der Linde, G., Armstrong, R., Phillips, D., Joy, S., Costa, J., Facatino, M., Posser, A., Kumar, M., Wallace, C., Chinn, I., Henning, A.Kimberlites from central Angola: a case study of exploration findings.Proceedings of the 10th. International Kimberlite Conference, Vol. 2, pp. 173-190.Africa, AngolaExploration - kimberlites
DS201412-0917
2014
Phillips, D.Tappe, S., Kjarsgaard, B.A., Kurszlaukis, S., Nowell, G.M., Phillips, D.Petrology and Nd-Hf isotope geochemistry of the Neoproterozoic Amon kimberlite sills, Baffin Island ( Canada): evidence of deep mantle magmatic activity linked to Supercontinent cycles.Journal of Petrology, Vol. 55, 10, pp. 2003-2042.Canada, Nunavut, Baffin IslandDeposit - Amon sills
DS201412-0993
2014
Phillips, D.Woodhead, J., Hergt, J., Phillips, D.Carbonate metasomatism at the continental scale: insights from kimberlite hosted zircon megacrysts.Goldschmidt Conference 2014, 1p. AbstractMantleMetasomatism
DS201601-0018
2016
Phillips, D.Giuliani, A., Phillips, D., Kamenetsky, V.S., Goemann, K.Constraints on kimberlite ascent mechanisms revealed by phlogopite compositions in kimberlites and mantle xenoliths.Lithos, Vol. 240, pp. 189-201.Africa, South AfricaDeposit - Bultfontein

Abstract: Kimberlite magmas are of economic and scientific importance because they represent the major host to diamonds and are probably the deepest magmas from continental regions. In addition, kimberlite magmas transport abundant mantle and crustal xenoliths, thus providing fundamental information on the composition of the sub-continental lithosphere. Despite their importance, the composition and ascent mechanism(s) of kimberlite melts remain poorly constrained. Phlogopite is one of the few minerals that preserves a history of fluid migration and magmatism in the mantle and crust and is therefore an invaluable petrogenetic indicator of kimberlite magma evolution. Here we present major and trace element compositional data for phlogopite from the Bultfontein kimberlite (Kimberley, South Africa; i.e. the kimberlite type-locality) and from entrained mantle xenoliths. Phlogopite macrocrysts (~ > 0.3-0.5 mm) and microcrysts (between ~ 0.1 and 0.3 mm) in the Bultfontein kimberlite display concentric compositional zoning patterns. The cores of these phlogopite grains exhibit compositions typical of phlogopite contained in peridotite mantle xenoliths. However, the rims of some grains show compositions analogous to kimberlite groundmass phlogopite (i.e. high Ti, Al and Ba; low Cr), whereas other rims and intermediate zones (between cores and rims) exhibit unusually elevated Cr and lower Al and Ba concentrations. The latter compositions are indistinguishable from matrix phlogopite in polymict breccia xenoliths (considered to represent failed kimberlite intrusions) and from Ti-rich overgrowth rims on phlogopite in other mantle xenoliths. Consequently, it is likely that these phlogopite grains crystallized from kimberlite melts and that the high Ti-Cr zones originated from earlier kimberlite melts at mantle depths. We postulate that successive pulses of ascending kimberlite magma progressively metasomatised the conduit along which later kimberlite pulses ascended, producing progressively decreasing interaction with the surrounding mantle rocks. In our view, these processes represent the fundamental mechanism of kimberlite magma ascent. Our study also indicates that, in addition to xenoliths/xenocrysts and magmatic phases, kimberlite rocks incorporate material crystallized at various mantle depths by previous kimberlite intrusions (mantle-derived ‘antecrysts’).
DS201606-1119
2016
Phillips, D.Soltys, A., Giuliani, A., Phillips, D., Kamenetsky, V.S., Maas, R., Woodhead, J., Rodemann, T.In-situ assimilation of mantle minerals by kimberlitic magmas - direct evidence from a garnet wehrlite xenolith entrained in the Bultfontein kimberlite ( Kimberley, South Africa).Lithos, Vol. 256-257, pp. 182-196.Africa, South AfricaDeposit - Bultfontein

Abstract: The lack of consensus on the possible range of initial kimberlite melt compositions and their evolution as they ascend through and interact with mantle and crustal wall rocks, hampers a complete understanding of kimberlite petrogenesis. Attempts to resolve these issues are complicated by the fact that kimberlite rocks are mixtures of magmatic, xenocrystic and antecrystic components and, hence, are not directly representative of their parental melt composition. Furthermore, there is a lack of direct evidence of the assimilation processes that may characterise kimberlitic melts during ascent, which makes understanding their melt evolution difficult. In this contribution we provide novel constraints on the interaction between precursor kimberlite melts and lithospheric mantle wall rocks. We present detailed textural and geochemical data for a carbonate-rich vein assemblage that traverses a garnet wehrlite xenolith [equilibrated at ~ 1060 °C and 43 kbar (~ 140-145 km)] from the Bultfontein kimberlite (Kimberley, South Africa). This vein assemblage is dominated by Ca-Mg carbonates, with subordinate oxide minerals, olivine, sulphides, and apatite. Vein phases have highly variable compositions indicating formation under disequilibrium conditions. Primary inclusions in the vein minerals and secondary inclusion trails in host wehrlite minerals contain abundant alkali-bearing phases (e.g., Na-K bearing carbonates, Mg-freudenbergite, Na-bearing apatite and phlogopite). The Sr-isotope composition of vein carbonates overlaps those of groundmass calcite from the Bultfontein kimberlite, as well as perovskite from the other kimberlites in the Kimberley area. Clinopyroxene and garnet in the host wehrlite are resorbed and have Si-rich reaction mantles where in contact with the carbonate-rich veins. Within some veins, the carbonates occur as droplet-like, globular segregations, separated from a similarly shaped Si-rich phase by a thin meniscus of Mg-magnetite. These textures are interpreted to represent immiscibility between carbonate and silicate melts. The preservation of reaction mantles, immiscibility textures and disequilibrium in the vein assemblage, suggests quenching, probably triggered by entrainment and rapid transport toward the Earth's surface in the host kimberlite magma. Based on the Sr-isotope systematics of vein carbonate minerals, and the close temporal relationship between carbonate-rich metasomatism and kimberlite magmatism, we suggest that the carbonate-rich vein assemblage was produced by the interaction between a melt genetically related to the Bultfontein kimberlite and wehrlitic mantle wall rock. If correct, this unique xenolith sample provides a rare snapshot of the assimilation processes that might characterise parental kimberlite melts during their ascent through the lithospheric mantle.
DS201610-1838
2016
Phillips, D.Abersteiner, A., Giuliani, A., Kamenetsky, V.S., Phillips, D.Petrographic and melt inclusion constraints on the petrogenesis of a magmaclast from the Venetia kimberlite cluster, South Africa.Chemical Geology, in press available 11p.Africa, South AfricaDeposit - Venetia

Abstract: Kimberlitic magmaclasts are discrete ovoid magmatic fragments that formed prior to emplacement from disrupted kimberlite magma. To provide new constraints on the origin and evolution of the kimberlite melts, we document the mineralogy and petrography of a magmaclast recovered from one of the ca. 520 Ma Venetia kimberlites, South Africa. The sample (BI9883) has a sub-spherical shape and consists of a ~ 10 mm diameter central olivine macrocryst, surrounded by porphyritic kimberlite. The kimberlitic material consists of concentrically aligned, altered olivine phenocrysts, set in a crystalline groundmass of calcite, chromite, perovskite, phlogopite, apatite, ilmenite, titanite, sulphides, rutile and magnetite along with abundant alteration phases (i.e. serpentine, talc and secondary calcite). These features are typical of archetypal hypabyssal kimberlites. We examined primary fluid/melt inclusions in chromite, perovskite and apatite containing a diversity of daughter phases. Chromite and perovskite host polycrystalline inclusions containing abundant alkali-carbonates (i.e. enriched in K, Na, Ba, Sr), phosphates, Na-K chlorides, sulphides and equal to lesser quantities of olivine, phlogopite and pleonaste. In contrast, apatite hosts polycrystalline assemblages with abundant alkali-carbonates and Na-K chlorides and lesser amounts of olivine, monticellite and phlogopite. Numerous solid inclusions of shortite (Na2Ca2(CO3)3), Na-Sr-carbonates and apatite occur in groundmass calcite along with fluid inclusions containing daughter crystals of Na-carbonates and Na-chlorides. The primary inclusions in chromite, perovskite and apatite are considered to represent remnants of fluid(s)/melt(s) trapped during crystallisation of the host minerals, whereas the fluid inclusions in calcite are probably secondary in origin. The component proportions of these primary fluid/melt inclusions were estimated in an effort to constrain the composition of the evolving kimberlite melt. These estimates suggest melt evolution from a silicate-carbonate kimberlite melt that became increasingly enriched in carbonates, phosphates, alkalis and chlorides, in response to the fractional crystallisation of constituent minerals (i.e. olivine to apatite). The concentric alignment of crystals around the olivine kernel and ovoid shape of the magmaclast can be ascribed to the low viscosity of the kimberlite melt and rapid rotation whilst in a liquid or partial crystalline state, or to progressive layer-by-layer growth of the magmaclast. Although the mineralogy of our sample is similar to hypabyssal kimberlites worldwide, it differs from hypabyssal kimberlite units in the main Venetia pipes, which contain monticellite-phlogopite rich assemblages and segregationary matrix textures. Therefore magmaclast BI9883 probably originated from a batch of magma distinct from those that produced known hypabyssal units within the Venetia kimberlite cluster.-
DS201611-2110
2016
Phillips, D.Giuliani, A., Soltys, A., Phillips, D., Kamenetsly, V.S., Maas, R., Geomann, K., Woodhead, J.D., Drysdale, R.N., Griffin, W.L.The final stages of kimberlite petrogenesis: petrography, mineral chemistry, melt inclusions and Sr-C-O isotope geochemistry of the Bultfontein kimberlite ( Kimberley, South Africa).Chemical Geology, in press available 15p.Africa, South AfricaDeposit - Bultfontein

Abstract: The petrogenesis of kimberlites commonly is obscured by interaction with hydrothermal fluids, including deuteric (late-magmatic) and/or groundwater components. To provide new constraints on the modification of kimberlite rocks during overprinting by such fluids and on the fractionation of kimberlite magmas during crystallisation, we have undertaken a detailed petrographic and geochemical study of a hypabyssal sample (BK) from the Bultfontein kimberlite (Kimberley, South Africa).
DS201707-1299
2017
Phillips, D.Abersteiner, A., Giuliani, A., Kamenetsky, V.S., Phillips, D.Petrographic and melt inclusion constraints on the petrogenesis of a magmaclast from the Venetia kimberlite cluster, South Africa.Chemical Geology, Vol. 455, pp. 331-341.Africa, South Africadeposit - Venetia

Abstract: Kimberlitic magmaclasts are discrete ovoid magmatic fragments that formed prior to emplacement from disrupted kimberlite magma. To provide new constraints on the origin and evolution of the kimberlite melts, we document the mineralogy and petrography of a magmaclast recovered from one of the ca. 520 Ma Venetia kimberlites, South Africa. The sample (BI9883) has a sub-spherical shape and consists of a ~ 10 mm diameter central olivine macrocryst, surrounded by porphyritic kimberlite. The kimberlitic material consists of concentrically aligned, altered olivine phenocrysts, set in a crystalline groundmass of calcite, chromite, perovskite, phlogopite, apatite, ilmenite, titanite, sulphides, rutile and magnetite along with abundant alteration phases (i.e. serpentine, talc and secondary calcite). These features are typical of archetypal hypabyssal kimberlites. We examined primary fluid/melt inclusions in chromite, perovskite and apatite containing a diversity of daughter phases. Chromite and perovskite host polycrystalline inclusions containing abundant alkali-carbonates (i.e. enriched in K, Na, Ba, Sr), phosphates, Na-K chlorides, sulphides and equal to lesser quantities of olivine, phlogopite and pleonaste. In contrast, apatite hosts polycrystalline assemblages with abundant alkali-carbonates and Na-K chlorides and lesser amounts of olivine, monticellite and phlogopite. Numerous solid inclusions of shortite (Na2Ca2(CO3)3), Na-Sr-carbonates and apatite occur in groundmass calcite along with fluid inclusions containing daughter crystals of Na-carbonates and Na-chlorides. The primary inclusions in chromite, perovskite and apatite are considered to represent remnants of fluid(s)/melt(s) trapped during crystallisation of the host minerals, whereas the fluid inclusions in calcite are probably secondary in origin. The component proportions of these primary fluid/melt inclusions were estimated in an effort to constrain the composition of the evolving kimberlite melt. These estimates suggest melt evolution from a silicate-carbonate kimberlite melt that became increasingly enriched in carbonates, phosphates, alkalis and chlorides, in response to the fractional crystallisation of constituent minerals (i.e. olivine to apatite). The concentric alignment of crystals around the olivine kernel and ovoid shape of the magmaclast can be ascribed to the low viscosity of the kimberlite melt and rapid rotation whilst in a liquid or partial crystalline state, or to progressive layer-by-layer growth of the magmaclast. Although the mineralogy of our sample is similar to hypabyssal kimberlites worldwide, it differs from hypabyssal kimberlite units in the main Venetia pipes, which contain monticellite-phlogopite rich assemblages and segregationary matrix textures. Therefore magmaclast BI9883 probably originated from a batch of magma distinct from those that produced known hypabyssal units within the Venetia kimberlite cluster.
DS201707-1327
2017
Phillips, D.Giuliani, A., Soltys, A., Phillips, D., Kamenetsky, V.S., Maas, R., Goemann, K., Woodhead, J.D., Drysdale, R.N., Griffin, W.L.The final stages of kimberlite petrogenesis: petrography, mineral chemistry, melt inclusions and Sr-C-O isotope geochemistry of the Bultfontein kimberlite ( Kimberley, South Africa.Chemical Geology, Vol. 455, pp. 342-256.Africa, South Africadeposit - Bultfontein

Abstract: The petrogenesis of kimberlites is commonly obscured by interaction with hydrothermal fluids, including deuteric (late-magmatic) and/or groundwater components. To provide new constraints on the modification of kimberlite rocks during fluid interaction and the fractionation of kimberlite magmas during crystallisation, we have undertaken a detailed petrographic and geochemical study of a hypabyssal sample (BK) from the Bultfontein kimberlite (Kimberley, South Africa). Sample BK consists of abundant macrocrysts (> 1 mm) and (micro-) phenocrysts of olivine and lesser phlogopite, smaller grains of apatite, serpentinised monticellite, spinel, perovskite, phlogopite and ilmenite in a matrix of calcite, serpentine and dolomite. As in kimberlites worldwide, BK olivine grains consist of cores with variable Mg/Fe ratios, overgrown by rims that host inclusions of groundmass phases (spinel, perovskite, phlogopite) and have constant Mg/Fe, but variable Ni, Mn and Ca concentrations. Primary multiphase inclusions in the outer rims of olivine and in Fe-Ti-rich (‘MUM’) spinel are dominated by dolomite, calcite and alkali carbonates with lesser silicate and oxide minerals. Secondary inclusions in olivine host an assemblage of Na-K carbonates and chlorides. The primary inclusions are interpreted as crystallised alkali-Si-bearing Ca-Mg-rich carbonate melts, whereas secondary inclusions host Na-K-rich C-O-H-Cl fluids. In situ Sr-isotope analyses of groundmass calcite and perovskite reveal similar 87Sr/86Sr ratios to perovskite in the Bultfontein and the other Kimberley kimberlites, i.e. magmatic values. The ?18O composition of the BK bulk carbonate fraction is above the mantle range, whereas the ?13C values are similar to those of mantle-derived magmas. The occurrence of different generations of serpentine and occasional groundmass calcite with high 87Sr/86Sr, and elevated bulk carbonate ?18O values indicate that the kimberlite was overprinted by hydrothermal fluids, which probably included a significant groundwater component. Before this alteration the groundmass included calcite, monticellite, apatite and minor dolomite, phlogopite, spinel, perovskite and ilmenite. Inclusions of groundmass minerals in olivine rims and phlogopite phenocrysts show that olivine and phlogopite also belong to the magmatic assemblage. We therefore suggest that the crystallised kimberlite was produced by an alkali-bearing, phosphorus-rich, silica-dolomitic melt. The alkali-Si-bearing Ca-Mg-rich carbonate compositions of primary melt inclusions in the outer rims of olivine and in spinel grains with evolved compositions (MUM spinel) support formation of these melts after fractionation of abundant olivine, and probably other phases (e.g., ilmenite and chromite). Finally, the similarity between secondary inclusions in kimberlite olivine of this and other worldwide kimberlites and secondary inclusions in minerals of carbonatitic, mafic and felsic magmatic rocks, suggests trapping of residual Na-K-rich C-O-H-Cl fluids after groundmass crystallisation. These residual fluids may have persisted in pore spaces within the largely crystalline BK groundmass and subsequently mixed with larger volumes of external fluids, which triggered serpentine formation and localised carbonate recrystallisation.
DS201708-1583
2017
Phillips, D.Woodhead, J., Hergt, J., Guiliani, A., Phillips, D., Maas, R.Tracking continental style scale modification of the Earth's mantle using zircon megacrysts. KimberlitesGeochemical Perspectives Letters, Vol. 4, pp. 1-6.Africa, South Africa, Zimbabwemetasomatism, geochronology

Abstract: Metasomatism, the chemical alteration of rocks by a variety of melts and fluids, has formed a key concept in studies of the Earth’s mantle for decades. Metasomatic effects are often inferred to be far-reaching and yet the evidence for their occurrence is usually based upon individual hand specimens or suites of rocks that display considerable heterogeneity. In rare cases, however, we are offered insights into larger-scale chemical modifications that occur in the mantle. Here we utilise the Lu–Hf systematics of zircon megacrysts erupted in kimberlite magmas to discern two temporally and compositionally discrete metasomatic events in the mantle beneath southern Africa, each having an influence extending over an area exceeding one million km2. These data provide unambiguous evidence for metasomatic processes operating at continental scales and seemingly unperturbed by the age and composition of the local lithospheric mantle. The most recent of these events may be associated with the major Jurassic-Karoo magmatism in southern Africa.
DS201708-1735
2017
Phillips, D.Phillips, D.Provenance history of detrital diamond deposits, West Coast of Namqualand, South Africa.11th. International Kimberlite Conference, OralAfrica, South Africadeposit - Namaqualand
DS201708-1736
2017
Phillips, D.Phillips, D.A comparison of geochronology methods applied to kimberlites and related rocks from the Karelian craton, Finland.11th. International Kimberlite Conference, PosterEurope, Finlandgeochronology
DS201803-0450
2014
Phillips, D.Giuliani, A., Phillips, D., Maas, R., Woodhead, J.D., Kendrick, M.A., Greig, A., Armstrong, R.A., Chew, D., Kamenetsky, V.S., Fiorentini, M.L.LIMA U-Pb ages link lithospheric mantle metasomatism to Karoo magmatism beneath the Kimberley region, South Africa.Earth and Planetary Science Letters, Vol. 401, pp. 132-147.Africa, South Africametasomatism

Abstract: The Karoo igneous rocks (174-185 Ma) of southern Africa represent one of the largest continental flood basalt provinces on Earth. Available evidence indicates that Karoo magmas either originated in the asthenosphere and were extensively modified by interaction with the lithospheric mantle prior to emplacement in the upper crust; or were produced by partial melting of enriched mantle lithosphere. However, no direct evidence of interaction by Karoo melts (or their precursors) with lithospheric mantle rocks has yet been identified in the suites of mantle xenoliths sampled by post-Karoo kimberlites in southern Africa. Here we report U-Pb ages for lindsleyite-mathiasite (LIMA) titanate minerals (crichtonite series) from three metasomatised, phlogopite and clinopyroxene-rich peridotite xenoliths from the ?84 Ma Bultfontein kimberlite (Kimberley, South Africa), located in the southern part of the Karoo magmatic province. The LIMA minerals appear to have formed during metasomatism of the lithospheric mantle by fluids enriched in HFSE (Ti, Zr, Hf, Nb), LILE (K, Ba, Ca, Sr) and LREE. LIMA U-Pb elemental and isotopic compositions were measured in situ by LA-ICP-MS methods, and potential matrix effects were evaluated by solution-mode analysis of mineral separates. LIMA minerals from the three samples yielded apparent U-Pb ages of , and (). A single zircon grain extracted from the ?190 Ma LIMA-bearing sample produced a similar U-Pb age of , within uncertainty of the LIMA ages. These data provide the first robust evidence of fluid enrichment in the lithospheric mantle beneath the Kimberley region at ?180-190 Ma, and suggest causation of mantle metasomatism by Karoo melts or their precursor(s). The results further indicate that U-Pb dating of LIMA minerals provides a new, accurate tool for dating metasomatic events in the lithospheric mantle.
DS201803-0451
2018
Phillips, D.Giuliani, A., Woodhead, J.D., Phillips, D., Maas, R., Davies, G.R.Titanates of the lindsleyite mathiasite ( LIMA) group reveal isotope disequilibrium associated with metasomatism in the mantle beneath Kimberley ( South Africa).Earth and Planetary Science Letters, Vol. 482, pp. 253-264.Africa, South Africametasomatism

Abstract: Radiogenic isotope variations unrelated to radiogenic ingrowth are common between minerals found in metasomatised mantle xenoliths entrained in kimberlite, basalts and related magmas. As the metasomatic minerals are assumed to have been in isotopic equilibrium originally, such variations are typically attributed to contamination by the magma host and/or interaction with mantle fluids during or before xenolith transport to surface. However, the increasing evidence of metasomatism by multiple, compositionally distinct fluids permeating the lithospheric mantle, coeval with specific magmatic events, suggests that isotopic disequilibrium might be a consequence of discrete, though complex, metasomatic events. Here we provide clear evidence of elemental and Sr isotope heterogeneity between coeval Ti-rich LIMA (lindsleyite–mathiasite) minerals at the time of their formation in the mantle. LIMA minerals occur in close textural association with clinopyroxene and phlogopite in low-temperature (?800–900?°C), strongly metasomatised mantle xenoliths from the ?84 Ma Bultfontein kimberlite (South Africa). Previous U/Pb dating of the LIMA phases was used to argue that each xenolith recorded a single event of LIMA crystallisation at ?180–190 Ma, coeval with the emplacement of Karoo magmas. SEM imaging reveals that up to four types of LIMA phases coexist in each xenolith, and occasionally in a single LIMA grain. Major element and in situ Sr isotope analyses of the different LIMA types show that each phase has a distinct elemental composition and initial 87Sr/86Sr ratio (e.g., 0.7068–0.7086 and 0.7115–0.7129 for two LIMA types in a single xenolith; 0.7053-0.7131 across the entire sample suite). These combined age and isotopic constraints require that multiple fluids metasomatised these rocks at broadly the same time (i.e. within a few thousands to millions of years), and produced similar mineralogical features. Elemental and isotopic variations between different LIMA types could be due to interaction between one (or more) Karoo-related Ti-rich silicate melts and previously metasomatised, phlogopite-rich lithospheric mantle. This study demonstrates that mantle metasomatic assemblages seemingly generated in a single event may instead result from the infiltration of broadly coeval fluids with variable compositions. This in turn implies that the isotopic variations recorded in mantle rocks may be an inherent feature of metasomatism, and that hot fluids infiltrating a rock do not necessarily cause equilibration at the cm scale, as has been assumed previously. Simple modelling of solid-state diffusion in mantle minerals shows that isotopic disequilibrium may be preserved for up to hundreds of Myr at mantle lithosphere temperatures (?1100–1200?°C), unless subsequently affected by transient heating and/or fluid infiltration events. Radiogenic isotope disequilibrium associated with mantle metasomatism may therefore be a common feature of mantle xenoliths.
DS201803-0477
2018
Phillips, D.Soltys, A., Giuliani, A., Phillips, D.A new approach to reconstructing the composition and evolution of kimberlite melts: a case study of the archetypal Bultfontein kimberlite ( Kimberley, South Africa).Lithos, in press available Africa, South Africadeposit - Bultfontein

Abstract: The compositions of kimberlite melts at depth and upon emplacement in the upper crust remain elusive. This can be attributed to the unquantified effects of multiple processes, such as alteration, assimilation, xenocryst contamination, and fractional crystallisation. The inability to accurately constrain the composition and physical properties of kimberlite melts prevents a comprehensive understanding of their petrogenesis. To improve constraints on the compositions of kimberlite melts, we have combined modal analysis including the discrimination of xenocrystic from magmatic phases, with mineral chemistry determinations to reconstruct a whole-rock composition. We apply this approach to a sample of “fresh” macrocrystic hypabyssal kimberlite (sample BK-1) from the Bultfontein mine (Kimberley, South Africa). The accuracy of this whole-rock reconstruction method is validated by the similarity between reconstructed and measured whole-rock compositions. A series of corrections are then applied to account for the effects of post-emplacement serpentinisation, pre-emplacement olivine crystallisation, and the inclusion and assimilation of mantle material. This approach permits discernment of melt compositions at different stages of kimberlite evolution. The primitive melt parental to the Bultfontein kimberlite is estimated to contain 17.4-19.0?wt% SiO2, 20.2-22.8?wt% MgO, 20.9-21.9?wt% CaO, 2.1-2.3?wt% P2O5, 1.2-1.4?wt% TiO2, 0.9-1.1?wt% Al2O3, and 0.6-0.7?wt% K2O, and has a Mg# of 83.4-84.4. Primary volatile contents (i.e., after an attempt to account for volatile loss) are tentatively estimated at ~2.1-2.2?wt% H2O and ~22.9-25.4?wt% CO2. This composition is deficient in SiO2, MgO and H2O, but enriched in CaO and CO2 compared with most previous estimates of primitive kimberlite melts. We suggest that the primitive melt parental to the Bultfontein kimberlite was a transitional silicate-carbonate melt, which was progressively enriched in SiO2, MgO, Al2O3, Cr2O3, and Na2O through the assimilation of lithospheric mantle material. Comparisons with experimentally produced low-degree melts of carbonated lherzolite indicate that the Bultfontein kimberlite could have formed by ~0.5% melting of asthenospheric mantle at ~6.0-8.6?GPa (i.e., ~190-285?km) and ~1400-1500?°C. The low calculated Na2O contents (<0.2?wt%), which are inconsistent with derivation from low-degree melting of lherzolite, suggest that an alkali-bearing, volatile-rich fluid was exsolved during ascent or released after emplacement, and subsequently removed.
DS201806-1223
2018
Phillips, D.Fitzpayne, A., Giuliani, A., Phillips, D., Wu, N.Kimberlite related metasomatism recorded in Marid and PIC mantle xenoliths. Kimberlites and orangeitesMineralogy and Petrology, in press available, 14p.Africa, South Africadeposit - Bultfontein

Abstract: MARID (Mica-Amphibole-Rutile-Ilmenite-Diopside) and PIC (Phlogopite-Ilmenite-Clinopyroxene) xenoliths are thought to be formed by intense Bprimary^ mantle metasomatism. These rocks also display secondary features, such as cross-cutting veins and geochemical zonation of matrix minerals, which probably reflect latermetasomatic events. To investigate the nature and origin(s) of these secondary features, 28 MARID and PIC xenoliths from southern African kimberlites and orangeites have been studied. MARID-hosted veins contain both carbonate and Ti-rich phases (e.g., titanite, phlogopite), suggesting that they formed by the infiltration of a carbonated silicate melt. Elevated TiO2 contents in MARID matrix mineral rims are spatially associated with carbonate-dominated veins, suggesting a genetic relationship between vein formation and geochemical zonation. Spongy rims around primaryMARID and PIC clinopyroxene are depleted in Na2O andAl2O3 relative to their cores, possibly reflecting mineral dissolution in the xenoliths during ascent and emplacement of the entraining kimberlite. The preservation of compositional differences between primary and secondary phases in MARID and PIC xenoliths indicates that metasomatism occurred shortly before, or broadly coeval with, kimberlite/orangeite magmatism; otherwise, at typical mantle temperatures, such features would have quickly re-equilibrated. Increased Na2O in some mineral rims (e.g., K-richterite) may therefore reflect equilibration with a more Na-enriched primitive kimberlite melt composition than is commonly suggested. Vein-hosted clinopyroxene 87Sr/86Sri (0.70539 ± 0.00079) in one MARID sample is intermediate between primary clinopyroxene in the sample (0.70814 ± 0.00002) and the host Bultfontein kimberlite (0.70432 ± 0.00005), suggesting that vein minerals are derived from interactions between primary MARID phases and kimberlite-related melts/fluids. Sulfur isotope compositions of barite (?34SVCDT = +4.69 ‰) and sulfides (?34SVCDT = ?0.69 ‰) in carbonate veins reflect equilibration at temperatures of 850-900 °C, consistent with sulfurrich melt/fluid infiltration in the lithospheric mantle. In contrast, vein carbonate C-O isotope systematics (?13CVPDB = ?9.18 ‰ ?18OVSMOW = +17.22‰) are not typical of kimberlites or other mantle carbonates (?13CVPDB = ?3 to ?8‰ ?18OVSMOW = 6 to 9 ), and may represent post-emplacement hydrothermal interactions of the cooling kimberlite with crustal fluids. These constraints suggest protracted metasomatism of MARID rocks shortly before and during entrainment by the host kimberlite.
DS201807-1489
2018
Phillips, D.Farr, H., Phillips, D., Maas, R., de Wit, M.Petrography, Sr isotope geochemistry and geochronology of the Nxau-Nxau kimberlites, north west Botswana.Mineralogy and Petrology, June 14, DOI:10.1007/ s00710-018- 0593-8, 14p.Africa, Botswanadeposit - Nxau

Abstract: The Nxau Nxau kimberlites in northwest Botswana belong to the Xaudum kimberlite province that also includes the Sikereti, Kaudom and Gura kimberlite clusters in north-east Namibia. The Nxau Nxau kimberlites lie on the southernmost extension of the Congo Craton, which incorporates part of the Damara Orogenic Belt on its margin. The Xaudum kimberlite province is geographically isolated from other known clusters but occurs within the limits of the NW-SE oriented, Karoo-aged Okavango Dyke Swarm and near NE-SW faults interpreted as the early stages of the East African Rift System. Petrographic, geochronological and isotopic studies were undertaken to characterise the nature of these kimberlites and the timing of their emplacement. The Nxau Nxau kimberlites exhibit groundmass textures, mineral phases and Sr-isotope compositions (87Sr/86Sri of 0.7036?±?0.0002; 2?) that are characteristic of archetypal (Group I) kimberlites. U-Pb perovskite, 40Ar/39Ar phlogopite and Rb-Sr phlogopite ages indicate that the kimberlites were emplaced in the Cretaceous, with perovskite from four samples yielding a preferred weighted average U-Pb age of 84?±?4 Ma (2?). This age is typical of many kimberlites in southern Africa, indicating that the Xaudum occurrences form part of this widespread Late Cretaceous kimberlite magmatic province. This time marks a significant period of tectonic stress reorganisation that could have provided the trigger for kimberlite magmatism. In this regard, the Nxau Nxau kimberlites may form part of a NE-SW oriented trend such as the Lucapa corridor, with implications for further undiscovered kimberlites along this corridor.
DS201807-1523
2018
Phillips, D.Phillips, D., Harris, J.W., de Wit, M.C.J., Matchan, E.L.Provenance history of detrital diamond deposits, West Coast of Namaqualand, South Africa.Mineralogy and Petrology, 10.1007/ s00710-018- 0568-9, 15p.Africa, South Africageochronology

Abstract: The West Coast of Namaqualand in South Africa hosts extensive detrital diamond deposits, but considerable debate exists as to the provenance of these diamonds. Some researchers have suggested derivation of the diamonds from Cretaceous-Jurassic kimberlites (also termed Group I kimberlites) and orangeites (also termed Group II kimberlites) located on the Kaapvaal Craton. However, others favour erosion of diamonds from the ca.300 Ma Dwyka Group sediments, with older, pre-Karoo kimberlites being the original source(s). Previous work has demonstrated that 40Ar/39Ar analyses of clinopyroxene inclusions, extracted from diamonds, yield ages approaching the time(s) of source kimberlite emplacement, which can be used to constrain the provenance of placer diamond deposits. In the current study, 40Ar/39Ar analyses were conducted on clinopyroxene inclusions from two similar batches of Namaqualand detrital diamonds, yielding (maximum) ages ranging from 117.5?±?43.6 Ma to 3684?±?191 Ma (2?) and 120.6?±?15.4 Ma to 688.8?±?4.9 Ma (2?), respectively. The vast majority of inclusions (88%) produced ages younger than 500 Ma, indicating that most Namaqualand diamonds originated from Cretaceous-Jurassic kimberlites/orangeites, with few, if any, derived from the Dwyka tillites. The provenance of the Namaqualand diamonds from ca.115-200 Ma orangeites is consistent with Late Cretaceous paleo-drainage reconstructions, as these localities could have been sampled by the ‘paleo-Karoo’ River and transported to the West Coast via an outlet close to the current Olifants River mouth. At ca.90 Ma, this drainage system appears to have been captured by the ‘paleo-Kalahari’ River, a precursor to the modern Orange River system. This latter drainage is considered to have transported diamonds eroded from both ca.80-90 Ma kimberlites and ca.115-200 Ma orangeites to the West Coast, which were subsequently reworked along the Namibian coast, forming additional placer deposits.
DS201807-1527
2018
Phillips, D.Soltys, A., Giuliani, A., Phillips, D.Crystallisation sequence and magma evolution of the De Beers dyke ( Kimberley, South Africa).Mineralogy and Petrology, June 14, DOI:10.1007/ s00710-018 -0588-5, 16p.Africa, South Africadeposit - De Beers dyke

Abstract: We present petrographic and mineral chemical data for a suite of samples derived from the De Beers dyke, a contemporaneous, composite intrusion bordering the De Beers pipe (Kimberley, South Africa). Petrographic features and mineral compositions indicate the following stages in the evolution of this dyke: (1) production of antecrystic material by kimberlite-related metasomatism in the mantle (i.e., high Cr-Ti phlogopite); (2) entrainment of wall-rock material during ascent through the lithospheric mantle, including antecrysts; (3) early magmatic crystallisation of olivine (internal zones and subsequently rims), Cr-rich spinel, rutile, and magnesian ilmenite, probably on ascent to the surface; and (4) crystallisation of groundmass phases (i.e., olivine rinds, Fe-Ti-rich spinels, perovskite, apatite, monticellite, calcite micro-phenocrysts, kinoshitalite-phlogopite, barite, and baddeleyite) and the mesostasis (calcite, dolomite, and serpentine) on emplacement in the upper crust. Groundmass and mesostasis crystallisation likely forms a continuous sequence with deuteric/hydrothermal modification. The petrographic features, mineralogy, and mineral compositions of different units within the De Beers dyke are indistinguishable from one another, indicating a common petrogenesis. The compositions of antecrysts (i.e., high Cr-Ti phlogopite) and magmatic phases (e.g., olivine rims, magnesian ilmenite, and spinel) overlap those from the root zone intrusions of the main Kimberley pipes (i.e., Wesselton, De Beers, Bultfontein). However, the composition of these magmatic phases is distinct from those in ‘evolved’ intrusions of the Kimberley cluster (e.g., Benfontein, Wesselton water tunnel sills). Although the effects of syn-emplacement flow processes are evident (e.g., alignment of phases parallel to contacts), there is no evidence that the De Beers dyke has undergone significant pre-emplacement crystal fractionation (e.g., olivine, spinel, ilmenite). This study demonstrates the requirement for detailed petrographic and mineral chemical studies to assess whether individual intrusions are in fact ‘evolved’; and that dykes are not necessarily produced by differentiated magmas.
DS201807-1532
2018
Phillips, D.Timmerman, S., Honda, M., Phillips, D., Jaques, A.L., Harris, J.W.Noble gas geochemistry of fluid inclusions in South Africa diamonds: implications for the origin of diamond forming fluids. ( fibrous)Mineralogy and Petrology, 10.1007/ s710-018- 0603-x 15p.Africa, South Africadeposit - Finsch, De Beers Pool, Koffiefontein

Abstract: Fibrous diamond growth zones often contain abundant high-density fluid (HDF) inclusions and these provide the most direct information on diamond-forming fluids. Noble gases are incompatible elements and particularly useful in evaluating large-scale mantle processes. This study further constrains the evolution and origin of the HDFs by combining noble gas systematics with ?¹³C, N concentrations, and fluid inclusion compositions for 21 individual growth zones in 13 diamonds from the Finsch (n = 3), DeBeers Pool (n = 7), and Koffiefontein (n = 3) mines on the Kaapvaal Craton. C isotope compositions range from ?2.8 to ?8.6‰ and N contents vary between 268 and 867 at.ppm, except for one diamond with contents of <30 at.ppm N. Nine of the thirteen studied diamonds contained saline HDF inclusions, but the other four diamonds had carbonatitic or silicic HDF inclusions. Carbonatitic and silicic HDFs yielded low He concentrations, R/Ra (³He/?Hesample/³He/?Heair) values of 3.2–6.7, and low ??Ar/³?Ar ratios of 390–1940. Noble gas characteristics of carbonatitic-silicic HDFs appear consistent with a subducted sediment origin and interaction with eclogite. Saline HDFs are characterised by high He concentrations, with R/Ra mostly between 3.9 and 5.7, and a wide range in ??Ar/³?Ar ratios (389–30,200). The saline HDFs likely originated from subducted oceanic crust with low He but moderate Ar contents. Subsequent interaction of these saline HDFs with mantle peridotite could explain the increase in He concentrations and mantle-like He isotope composition, with the range in low to high ??Ar/³?Ar ratios dependent on the initial ³?Ar content and extent of lithosphere interaction. The observed negative correlation between ?He contents and R/Ra values in saline HDFs indicates significant in situ radiogenic ?He production. Noble gas geochemistry of fluid inclusions in South African diamonds: implications for the origin of diamond-forming fluids.
DS201808-1764
2018
Phillips, D.Lim, E., Giuliani, A., Phillips, D., Goemann, K.Origin of complex zoning in olivine from diverse, Diamondiferous kimberlites and tectonic settings: Ekati ( Canada), Alto Paranaiba ( Brazil) and Kaalvallei ( South Africa).Mineralogy and Petrology, doi.org/10.1007/s00710-018-0607-6 16p.Canada, Northwest Territories, South America, Brazildeposit - Ekati, Grizzly, Kaola, Limpeza-18, Tres Ranchos-04, Kaalvallei, Samada, New Robinson

Abstract: Olivine in kimberlites can provide unique insights into magma petrogenesis, because it is the most abundant xenocrystic phase and a stable magmatic product over most of the liquid line of descent. In this study we examined the petrography and chemistry of olivine in kimberlites from different tectonic settings, including the Slave craton, Canada (Ekati: Grizzly, Koala), the Brasilia mobile belt (Limpeza-18, Tres Ranchos-04), and the Kaapvaal craton, South Africa (Kaalvallei: Samada, New Robinson). Olivine cores display a wide range of compositions (e.g., Mg#?=?78-95). The similarity in olivine composition, resorption of core zones and inclusions of mantle-derived phases, indicates that most olivine cores originated from the disaggregation of mantle peridotites, including kimberlite-metasomatised lithologies (i.e. sheared lherzolites and megacrysts). Olivine rims typically show a restricted range of Mg#, with decreasing Ni and increasing Mn and Ca contents, a characteristic of kimberlitic olivine worldwide. The rims host inclusions of groundmass minerals, which implies crystallisation just before and/or during emplacement. There is a direct correlation between olivine rim composition and groundmass mineralogy, whereby high Mg/Fe rims are associated with carbonate-rich kimberlites, and lower Mg/Fe rims are correlated with increased phlogopite and Fe-bearing oxide mineral abundances. There are no differences in olivine composition between explosive (Grizzly) and hypabyssal (Koala) kimberlites. Olivine in kimberlites also displays transitional zones and less common internal zones, between cores and rims. The diffuse transitional zones exhibit intermediate compositions between cores and rims, attributed to partial re-equilibration of xenocrystic cores with the ascending kimberlite melt. In contrast, internal zones form discrete layers with resorbed margins and restricted Mg# values, but variable Ni, Mn and Ca concentrations, which indicates a discrete crystallization event from precursor kimberlite melts at mantle depths. Overall, olivine exhibits broadly analogous zoning in kimberlites worldwide. Variable compositions for individual zones relate to different parental melt compositions rather than variations in tectonic setting or emplacement mechanism.
DS201810-2315
2018
Phillips, D.Fitzpayne, A., Giuliani, A., Hergt, J., Phillips, D., Janney, P.New geochemical constraints on the origins of MARID and PIC rocks: implications for mantle metasomatism and mantle -derived potassic magmatism.Lithos, Vol. 318-319, pp. 478-493.Mantlemetasomatism
DS201810-2366
2018
Phillips, D.Phillips, D., Harris, J.W., de Wit, M.C.J., Matchan, E.Provenance history of detrital diamond deposits, West Coast of Namaqualand, South Africa.Mineralogy and Petrology, doi:10.1007/ s00710-018-0568-9 15p.Africa, South Africadeposit - Group I, orangeites Group II

Abstract: The West Coast of Namaqualand in South Africa hosts extensive detrital diamond deposits, but considerable debate exists as to the provenance of these diamonds. Some researchers have suggested derivation of the diamonds from Cretaceous-Jurassic kimberlites (also termed Group I kimberlites) and orangeites (also termed Group II kimberlites) located on the Kaapvaal Craton. However, others favour erosion of diamonds from the ca.300 Ma Dwyka Group sediments, with older, pre-Karoo kimberlites being the original source(s). Previous work has demonstrated that 40Ar/39Ar analyses of clinopyroxene inclusions, extracted from diamonds, yield ages approaching the time(s) of source kimberlite emplacement, which can be used to constrain the provenance of placer diamond deposits. In the current study, 40Ar/39Ar analyses were conducted on clinopyroxene inclusions from two similar batches of Namaqualand detrital diamonds, yielding (maximum) ages ranging from 117.5?±?43.6 Ma to 3684?±?191 Ma (2s) and 120.6?±?15.4 Ma to 688.8?±?4.9 Ma (2s), respectively. The vast majority of inclusions (88%) produced ages younger than 500 Ma, indicating that most Namaqualand diamonds originated from Cretaceous-Jurassic kimberlites/orangeites, with few, if any, derived from the Dwyka tillites. The provenance of the Namaqualand diamonds from ca.115-200 Ma orangeites is consistent with Late Cretaceous paleo-drainage reconstructions, as these localities could have been sampled by the ‘paleo-Karoo’ River and transported to the West Coast via an outlet close to the current Olifants River mouth. At ca.90 Ma, this drainage system appears to have been captured by the ‘paleo-Kalahari’ River, a precursor to the modern Orange River system. This latter drainage is considered to have transported diamonds eroded from both ca.80-90 Ma kimberlites and ca.115-200 Ma orangeites to the West Coast, which were subsequently reworked along the Namibian coast, forming additional placer deposits.
DS201812-2797
2018
Phillips, D.Das, H., Kobussen, A.F., Webb, K.J., Phillips, D., Maas, R., Soltys, A., Rayner, M.J., Howell, D.Bunder deposit: The Bunder diamond project, India: geology, geochemistry, and age of Saptarshi lamproite pipes.Society of Economic Geology Geoscience and Exploration of the Argyle, Bunder, Diavik, and Murowa Diamond Deposits, Special Publication no. 20, pp. 201-222.Indiadeposit - Bunder
DS201812-2809
2018
Phillips, D.Fitzpayne, A., Giuliani, A., Hergt, J., Phillips, D., Janney, P.New geochemical constraints on the origins of MARID and PIC rocks: implications for mantle metasomatism and mantle derived potassic magmatism. ( kimberlite)Lithos, Vol. 318-319, pp. 478-493.Globallamproites

Abstract: MARID (Mica-Amphibole-Rutile-Ilmenite-Diopside) and PIC (Phlogopite-Ilmenite-Clinopyroxene) rocks are unusual mantle samples entrained by kimberlites and other alkaline volcanic rocks. The formation of MARID rocks remains hotly debated. Although the incompatible element (for example, large ion lithophile element) enrichment in these rocks suggests that they formed by mantle metasomatism, the layered textures of some MARID samples (and MARID veins in composite xenoliths) are more indicative of formation by magmatic processes. MARID lithologies have also been implicated as an important source component in the genesis of intraplate ultramafic potassic magmas (e.g., lamproites, orangeites, ultramafic lamprophyres), due to similarities in their geochemical and isotopic signatures. To determine the origins of MARID and PIC xenoliths and to understand how they relate to alkaline magmatism, this study presents new mineral major and trace element data and bulk-rock reconstructions for 26 MARID and PIC samples from the Kimberley-Barkly West area in South Africa. Similarities between compositions of PIC minerals and corresponding phases in metasomatised mantle peridotites are indicative of PIC formation by pervasive metasomatic alteration of peridotites. MARID genesis remains a complicated issue, with no definitive evidence precluding either the magmatic or metasomatic model. MARID minerals exhibit broad ranges in Mg# (e.g., clinopyroxene Mg# from 82 to 91), which may be indicative of fractionation processes occurring in the MARID-forming fluid/melt. Finally, two quantitative modelling approaches were used to determine the compositions of theoretical melts in equilibrium with MARID rocks. Both models indicate that MARID-derived melts have trace element patterns resembling mantle-derived potassic magma compositions (e.g., lamproites, orangeites, ultramafic lamprophyres), supporting inferences that these magmas may originate from MARID-rich mantle sources.
DS201812-2851
2018
Phillips, D.Moss, S., Marten, B.E., Felgate, M., Smith, C.B., Chimuka, L., Matchan, E.L., Phillips, D.Murowa deposit: Geology, structure and radiometric age determination of the Murowa kimberlites, Zimbabwe.Society of Economic Geology Geoscience and Exploration of the Argyle, Bunder, Diavik, and Murowa Diamond Deposits, Special Publication no. 20, pp. 379-402.Africa, Zimbabwedeposit - Murowa
DS201902-0271
2019
Phillips, D.Fitzpayne, A., Giuliani, A., Maas, R., Hergt, J., Janney, P., Phillips, D.Progressive metasomatism of the mantle by kimberlite melts: Sr-Nd-Hf-Pb isotope compositions of MARID and PIC minerals.Earth and Planetary Science Letters, Vol. 506, pp. 15-26.Africa, South Africadeposit - Newlands, Kimberley, Bultfontein

Abstract: MARID (Mica-Amphibole-Rutile-Ilmenite-Diopside) and PIC (Phlogopite-Ilmenite-Clinopyroxene) rocks occur as mantle-derived xenoliths in kimberlites and other alkaline volcanic rocks. Both rock types are alkaline and ultramafic in composition. The H2O and alkali metal enrichments in MARID and PIC rocks, reflected in abundant phlogopite, have been suggested to be caused by extreme mantle metasomatism. Radiogenic (Sr-Nd-Hf-Pb) isotope and trace element compositions for mineral separates from MARID (clinopyroxene and amphibole) and PIC (clinopyroxene only) samples derived from Cretaceous kimberlites (Kimberley) and orangeites (Newlands) from South Africa are used here to examine the source(s) of mantle metasomatism. PIC clinopyroxene is relatively homogeneous, with narrow ranges in initial isotopic composition (calculated to the emplacement age of the host Bultfontein kimberlite; 87Sr/86Sri: 0.7037-0.7041; ?Ndi: +3.0 to +3.6; ?Hfi: +2.2 to +2.5; 206Pb/204Pbi: 19.72-19.94) similar to kimberlite values. This is consistent with PIC rocks representing peridotites modified by intense metasomatic interaction with kimberlite melts. The MARID clinopyroxene and amphibole separates () studied here display broader ranges in isotope composition (e.g., 87Sr/86Sri: 0.705-0.711; ?Ndi: ?11.0 to ?1.0; ?Hfi: ?17.9 to ?8.5; 206Pb/204Pbi: 17.33-18.72) than observed in previous studies of MARID rocks. The Nd-Hf isotope compositions of kimberlite-derived MARID samples fall below the mantle array (??Hfi between ?13.0 and ?2.4), a feature reported widely for kimberlites and other alkaline magmas. We propose that such displacements in MARID minerals result from metasomatic alteration of an initial “enriched mantle” MARID composition (i.e., 87Sr/86Sri = 0.711; ?Ndi = ?11.0; ?Hfi = ?17.9; and 206Pb/204Pbi = 17.3) by the entraining kimberlite magma (87Sr/86Sr; ?Nd; ?Hf; 206Pb/204Pb). A model simulating the flow of kimberlite magma through a mantle column, thereby gradually equilibrating the isotopic and chemical compositions of the MARID wall-rock with those of the kimberlite magma, broadly reproduces the Sr-Nd-Hf-Pb isotope compositions of the MARID minerals analysed here. This model also suggests that assimilation of MARID components could be responsible for negative ??Hfi values in kimberlites. The isotopic composition of the inferred initial MARID end-member, with high 87Sr/86Sr and low ?Nd, ?Hf, and 206Pb/204Pb, resembles those found in orangeites, supporting previous inferences of a genetic link between MARID-veined mantle and orangeites. The metasomatic agent that produced such compositions in MARID rocks must be more extreme than the EM-II mantle component and may relate to recycled material that experienced long-term storage in the lithospheric mantle.
DS201905-1078
2019
Phillips, D.Soltys, A., Giuliani, A., Phillips, D.Crystallization sequence and magma evolution of the De Beers dyke ( Kimberley, South Africa).Mineralogy and Petrology, doi.org/10.1007/ s00710-018-0588-5 17p.Africa, South Africadeposit - De Beers dyke

Abstract: We present petrographic and mineral chemical data for a suite of samples derived from the De Beers dyke, a contemporaneous, composite intrusion bordering the De Beers pipe (Kimberley, South Africa). Petrographic features and mineral compositions indicate the following stages in the evolution of this dyke: (1) production of antecrystic material by kimberlite-related metasomatism in the mantle (i.e., high Cr-Ti phlogopite); (2) entrainment of wall-rock material during ascent through the lithospheric mantle, including antecrysts; (3) early magmatic crystallisation of olivine (internal zones and subsequently rims), Cr-rich spinel, rutile, and magnesian ilmenite, probably on ascent to the surface; and (4) crystallisation of groundmass phases (i.e., olivine rinds, Fe-Ti-rich spinels, perovskite, apatite, monticellite, calcite micro-phenocrysts, kinoshitalite-phlogopite, barite, and baddeleyite) and the mesostasis (calcite, dolomite, and serpentine) on emplacement in the upper crust. Groundmass and mesostasis crystallisation likely forms a continuous sequence with deuteric/hydrothermal modification. The petrographic features, mineralogy, and mineral compositions of different units within the De Beers dyke are indistinguishable from one another, indicating a common petrogenesis. The compositions of antecrysts (i.e., high Cr-Ti phlogopite) and magmatic phases (e.g., olivine rims, magnesian ilmenite, and spinel) overlap those from the root zone intrusions of the main Kimberley pipes (i.e., Wesselton, De Beers, Bultfontein). However, the composition of these magmatic phases is distinct from those in ‘evolved’ intrusions of the Kimberley cluster (e.g., Benfontein, Wesselton water tunnel sills). Although the effects of syn-emplacement flow processes are evident (e.g., alignment of phases parallel to contacts), there is no evidence that the De Beers dyke has undergone significant pre-emplacement crystal fractionation (e.g., olivine, spinel, ilmenite). This study demonstrates the requirement for detailed petrographic and mineral chemical studies to assess whether individual intrusions are in fact ‘evolved’; and that dykes are not necessarily produced by differentiated magmas.
DS201909-2090
2019
Phillips, D.Soltys, A., Giuliani, A., Phillips, D.Apatite geochemistry provides insights into the late magmatic evolution of kimberlites.Goldschmidt2019, 1p. AbstractAfrica, South Africadeposit - Kimberley

Abstract: The late evolution of kimberlite magmas, i.e., during and-following emplacement into the upper crust, remains a-controversial aspect of kimberlite petrogenesis. Likewise, it is-unclear whether or not there is a link between melt composition-and the emplacement mechanism of intrusive kimberlites (i.e.,-planar dykes/sills vs. irregular intrusions in the root zone of-pipes). Resolving these issues is hampered by the absence of-comparative studies of late-magmatic kimberlite phases (e.g.,-apatite, monticellite, mica) in dykes, sills, and root-zone-intrusions from the same locality.-Here we report petrographic and mineral-chemical results-for groundmass phases in samples of dykes, sills, and root zone-intrusions from the Kimberley kimberlites (South Africa).-Early crystalised phases (e.g., olivine, spinel) in dykes/sills and-root-zone intrusions have indistingushable compositions, and-hence crystallised from similar primitive melts. Conversely,-apatite major element compositions are variable and can-discriminate dykes/sills (i.e., low and constant Sr, with-increasing Si) from root zone intrusions (high but variable Sr,-low and constant Si). The Sr depletion in root zone apatite is-interpreted to represent fractional crystallisation of earlier-apatite, perovskite, and calcite from a broadly similar parental-melt. Silica enrichment of apatite from dykes/sills may be-attributed to the coupled incorporation of CO32- and Si into the-apatite structure, reflecting higher CO2 contents in the melts-that formed dykes/sills. CO2 enrichment in the dykes/sills is-consistent with petrographic obervations. Dykes/sills are-enriched in carbonates, may contain dolomite, and are depleted-in mica and monticellite compared to the groundmass of rootzone-kimberlites. This suggests the melts parental to-dykes/sills have a higher CO2/H2O ratio compared to those-parental to root zone intrusions. These two distinct melt-evolution paths cannot be due to crustal contamination before-emplacement because the Sr-isotope compositions of latecrystallised-carbonates are indistinguishable in dykes/sills and-root-zone intrusions. We speculate that CO2 is better retained-in dykes/sills due to a higher confining pressure (i.e., lack of-breakthrough to the surface).-
DS201910-2253
2019
Phillips, D.Dalton, H., Giuliani, A., Phillips, D., Hergt, J., O'Brien, H.Petrographic and geochemical variations in the Kaavi-Kuopio kimberlite field, Finland: the role of mantle assimilation.Goldschmidt2019, 1p. AbstractEurope, Finlanddeposit - Kaavi-Kuopio

Abstract: Kimberlites are silica-poor, volatile-rich (CO2 ± H2O), volcanic rocks that are often described as ‘hybrid’, because their parental magmas include abundant xenocrystic (crustand mantle-derived) components. Unravelling the influence of mantle assimilation on kimberlite melt compositions represents an outstanding question of kimberlite petrology. To address this issue, we have carried out a comprehensive geochemical and petrographic investigation of nine kimberlites from the Kaavi-Kuopio field in Finland, that were emplaced on the southern margin of the Karelian Craton in the Neoproterozoic (~550-600 Ma). Olivine is the dominant mineral phase in kimberlites (~50 vol.%) with cores mainly derived from the disaggregation of mantle peridotite. In contrast, olivine rims crystallise directly from the kimberlitic melt and their Mg# (Mg/(Mg+Fe)) typically show remarkable homogeneity within and between kimberlites of a single cluster and field (e.g., Lac de Gras). The Kaavi-Kuopio kimberlites appear to represent a unique case where there is a (statistically) significant difference between the average Mg# of olivine rims in different pipes (89.9 ± 0.2 to 88.5 ± 0.3). Importantly, the Mg# of olivine rims exhibit a strong correlation with the Mg# of olivine cores. Furthermore, the compositions of olivine cores (and rims) exhibit a strong correlation with those of spinel (e.g., Mg#, TiO2 contents). These geochemical variations correlate with the modal mineralogy of the kimberlites: for example, higher abundances of monticellite and lower abundances of ilmenite are associated with higher Mg# olivine. The robust relationship between entrained and assimilated lithospheric mantle material (i.e. olivine cores) and magmatic components (i.e. olivine rims, spinel, and other groundmass minerals) suggests that assimilation of lithospheric mantle has impacted the compositions of kimberlitic melts to a greater extent than previously recognised. These new data also suggest significant variations in the composition of the mantle lithosphere beneath the Kaavi-Kuopio kimberlites, which are spaced less than 10 km apart.
DS201910-2257
2019
Phillips, D.Fitzpayne, A., Giuliani, A., Maas, R., Hergt, J., Janney, P., Phillips, D.Progressive metasomatism of the mantle by kimberliitic melts: Sr-Nd-Hf-Pb isotopic composition of MARID and PIC minerals.Goldschmidt2019, 1p. AbstractMantlemetasomatism

Abstract: MARID (Mica-Amphibole-Rutile-Ilmenite-Diopside) and PIC (Phlogopite-Ilmenite-Clinopyroxene) rocks occur as mantle-derived xenoliths in kimberlites and other alkaline volcanic rocks. Both rock types are alkaline and ultramafic in composition. The H2O and alkali metal enrichments in MARID and PIC rocks, reflected in abundant phlogopite, have been suggested to be caused by extreme mantle metasomatism. Radiogenic (Sr-Nd-Hf-Pb) isotope and trace element compositions for mineral separates from MARID (clinopyroxene and amphibole) and PIC (clinopyroxene only) samples derived from Cretaceous kimberlites (Kimberley) and orangeites (Newlands) from South Africa are used here to examine the source(s) of mantle metasomatism. PIC clinopyroxene ( n = 4 ) is relatively homogeneous, with narrow ranges in initial isotopic composition (calculated to the emplacement age of the host Bultfontein kimberlite; 87Sr/86Sri: 0.7037-0.7041; ?Ndi: +3.0 to +3.6; ?Hfi: +2.2 to +2.5; 206Pb/204Pbi: 19.72-19.94) similar to kimberlite values. This is consistent with PIC rocks representing peridotites modified by intense metasomatic interaction with kimberlite melts. The MARID clinopyroxene ( n = 9 ) and amphibole separates ( n = 11 ) studied here display broader ranges in isotope composition (e.g., 87Sr/86Sri: 0.705-0.711; ?Ndi: ?11.0 to ?1.0; ?Hfi: ?17.9 to ?8.5; 206Pb/204Pbi: 17.33-18.72) than observed in previous studies of MARID rocks. The Nd-Hf isotope compositions of kimberlite-derived MARID samples fall below the mantle array (??Hfi between ?13.0 and ?2.4), a feature reported widely for kimberlites and other alkaline magmas. We propose that such displacements in MARID minerals result from metasomatic alteration of an initial “enriched mantle” MARID composition (i.e., 87Sr/86Sri = 0.711; ?Ndi = ?11.0; ?Hfi = ?17.9; and 206Pb/204Pbi = 17.3) by the entraining kimberlite magma (87Sr/86Sr ? i 0.704 ; ?Nd ? i + 3.3 ; ?Hf ? i + 2.3 ; 206Pb/204Pb ? i 19.7 ). A model simulating the flow of kimberlite magma through a mantle column, thereby gradually equilibrating the isotopic and chemical compositions of the MARID wall-rock with those of the kimberlite magma, broadly reproduces the Sr-Nd-Hf-Pb isotope compositions of the MARID minerals analysed here. This model also suggests that assimilation of MARID components could be responsible for negative ??Hfi values in kimberlites. The isotopic composition of the inferred initial MARID end-member, with high 87Sr/86Sr and low ?Nd, ?Hf, and 206Pb/204Pb, resembles those found in orangeites, supporting previous inferences of a genetic link between MARID-veined mantle and orangeites. The metasomatic agent that produced such compositions in MARID rocks must be more extreme than the EM-II mantle component and may relate to recycled material that experienced long-term storage in the lithospheric mantle.
DS201910-2301
2019
Phillips, D.Soltys, A., Giuliani, A., Phillips, D.Apatite geochemistry provides insights into the Late magmatic evolution of kimberlites.Goldschmidt2019, 1p. AbstractMantlemagmatism

Abstract: The late evolution of kimberlite magmas, i.e., during and following emplacement into the upper crust, remains a controversial aspect of kimberlite petrogenesis. Likewise, it is unclear whether or not there is a link between melt composition and the emplacement mechanism of intrusive kimberlites (i.e., planar dykes/sills vs. irregular intrusions in the root zone of pipes). Resolving these issues is hampered by the absence of comparative studies of late-magmatic kimberlite phases (e.g., apatite, monticellite, mica) in dykes, sills, and root-zone intrusions from the same locality. Here we report petrographic and mineral-chemical results for groundmass phases in samples of dykes, sills, and root zone intrusions from the Kimberley kimberlites (South Africa). Early crystalised phases (e.g., olivine, spinel) in dykes/sills and root-zone intrusions have indistingushable compositions, and hence crystallised from similar primitive melts. Conversely, apatite major element compositions are variable and can discriminate dykes/sills (i.e., low and constant Sr, with increasing Si) from root zone intrusions (high but variable Sr, low and constant Si). The Sr depletion in root zone apatite is interpreted to represent fractional crystallisation of earlier apatite, perovskite, and calcite from a broadly similar parental melt. Silica enrichment of apatite from dykes/sills may be attributed to the coupled incorporation of CO32- and Si into the apatite structure, reflecting higher CO2 contents in the melts that formed dykes/sills. CO2 enrichment in the dykes/sills is consistent with petrographic obervations. Dykes/sills are enriched in carbonates, may contain dolomite, and are depleted in mica and monticellite compared to the groundmass of rootzone kimberlites. This suggests the melts parental to dykes/sills have a higher CO2/H2O ratio compared to those parental to root zone intrusions. These two distinct melt evolution paths cannot be due to crustal contamination before emplacement because the Sr-isotope compositions of latecrystallised carbonates are indistinguishable in dykes/sills and root-zone intrusions. We speculate that CO2 is better retained in dykes/sills due to a higher confining pressure (i.e., lack of breakthrough to the surface).
DS201910-2304
2019
Phillips, D.Tovey, M., Giuliani, A., Phillips, D., Moss, S.What controls the explosive emplacement of the diamondiferous Diavik kimberlites? New insights from mineral chemistry and petrography of hypbyssal and pyroclastic samples.Goldschmidt2019, 1p. AbstractCanada, Northwest Territoriesdeposit - Diavik

Abstract: Kimberlites are mantle-derived, CO2 and H2O rich magmas that entrain abundant mantle material, including diamonds during rapid ascent to the surface. Most kimberlite magmas that reach the upper crust either erupt explosively or are emplaced as shallow hypabyssal intrusions. Catastrophic volatile exsolution, local geology and stress regimes, and interaction with external water are suggested as possible controls of magma explosivity. A full understanding of the processes promoting the explosive emplacement of kimberlite magmas has been hindered by common alteration and crustal contamination of pyroclastic kimberlites (PK). To address this issue, we have undertaken a detailed petrographic and mineral-chemical study of fresh pyroclastic and hypabyssal kimberlites (i.e. dykes either cross-cutting or isolated from volcanic pipes) from the Diavik Diamond Mine (Lac de Gras, Canada). Diavik kimberlites feature the same olivine compositions regardless of emplacement style. The cross-cutting kimberlite dykes (xHK) and pyroclastic kimberlites also feature the same chromite (i.e. liquidus spinel) compositions, and spinel evolution to indistinguishable magnesian ulvospinel-magnetite compositions. These results demonstrate that primitive melt compositions, and early magmatic evolutionary trends are the same for kimberlite melts that erupt explosively or those that are emplaced as shallow intrusions. The magmaclasts in PKs contain higher abundances of phlogopite, and lower contents of carbonate than the groundmass of xHKs suggesting higher H2O/CO2 ratios in the magmas that erupt explosively. This finding highlights divergence of the PK and xHK parental melt compositions after late spinel formation, which underpins explosive CO2 exsolution only in some magmas. While the causes of explosive volcanism remain uncertain, our study indicates that primitive melt composition has no significant influence on the emplacement style of kimberlites.
DS201911-2575
2019
Phillips, D.Woodhead, J., Hergt, J., Giuliani, A., Maas, R., Phillips, D., Pearson, D.G., Nowell, G.Kimberlites reveal 2.5 billion year evolution of a deep, isolated mantle reservoir.Nature , Vol. 573, pp. 578-581.Mantlediamond genesis

Abstract: The widely accepted paradigm of Earth's geochemical evolution states that the successive extraction of melts from the mantle over the past 4.5 billion years formed the continental crust, and produced at least one complementary melt-depleted reservoir that is now recognized as the upper-mantle source of mid-ocean-ridge basalts1. However, geochemical modelling and the occurrence of high 3He/4He (that is, primordial) signatures in some volcanic rocks suggest that volumes of relatively undifferentiated mantle may reside in deeper, isolated regions2. Some basalts from large igneous provinces may provide temporally restricted glimpses of the most primitive parts of the mantle3,4, but key questions regarding the longevity of such sources on planetary timescales—and whether any survive today—remain unresolved. Kimberlites, small-volume volcanic rocks that are the source of most diamonds, offer rare insights into aspects of the composition of the Earth’s deep mantle. The radiogenic isotope ratios of kimberlites of different ages enable us to map the evolution of this domain through time. Here we show that globally distributed kimberlites originate from a single homogeneous reservoir with an isotopic composition that is indicative of a uniform and pristine mantle source, which evolved in isolation over at least 2.5 billion years of Earth history—to our knowledge, the only such reservoir that has been identified to date. Around 200 million years ago, extensive volumes of the same source were perturbed, probably as a result of contamination by exogenic material. The distribution of affected kimberlites suggests that this event may be related to subduction along the margin of the Pangaea supercontinent. These results reveal a long-lived and globally extensive mantle reservoir that underwent subsequent disruption, possibly heralding a marked change to large-scale mantle-mixing regimes. These processes may explain why uncontaminated primordial mantle is so difficult to identify in recent mantle-derived melts.
DS201912-2789
2019
Phillips, D.Heaman, L.H., Phillips, D., Pearson, D.G.Dating kimberlite: methods and emplacement patterns through time.Elements, Vol. 15, 6, pp.Mantlegeochronology
DS202002-0173
2019
Phillips, D.Dalton, H., Giuliani, A., O'Brien, H., Phillips, D., Hergt, J.The role of lithospheric heterogeneity on the composition of kimberlite magmas from a single field: the case of Kaavi-Kuopio, Finland.Lithos, in press available, 61p. PdfEurope, Finlanddeposit - Kaavi-Kuopio

Abstract: Kimberlites are complex, ‘hybrid’ igneous rocks because their parental magmas entrain abundant crust- and mantle-derived components that can be readily assimilated during ascent to surface. Recent studies of olivine zonation patterns have shown compositional relationships between xenocrystic cores and magmatic rims, suggesting that kimberlite melt compositions might be controlled by assimilation of mantle material during emplacement. However, the nature and extent to which this process, as well as assimilation of crustal material, influences melt compositions within single kimberlite fields remains unclear. To address this issue, we have conducted a comprehensive geochemical and petrographic investigation of kimberlites from eight pipes in the Kaavi-Kuopio field in Finland, which were emplaced on the southern margin of the Karelian craton during the Neoproterozoic (~550-600 Ma). While magmatic olivine rims are usually homogeneous in composition within and between kimberlites of a single cluster and field (e.g., Lac de Gras), the Kaavi-Kuopio kimberlites appear to represent a unique case where there are statistically significant differences between the average Mg# of olivine rims in different pipes (89.9 ± 0.2 to 88.5 ± 0.3). Importantly, the Mg# of magmatic olivine rims exhibit a strong correlation with the Mg# of their mantle-derived xenocrystic cores. Furthermore, the compositions of olivine cores and rims exhibit a robust relationship with those of magmatic spinel (e.g., Mg#, TiO2 contents). These geochemical variations also align with the mineralogy of the kimberlites: whereby abundances of phlogopite and oxides (e.g., spinel) are negatively correlated with olivine rim Mg#. The robust relationship between entrained and assimilated lithospheric mantle material (i.e. olivine cores) and magmatic components (i.e. olivine rims, spinel, and groundmass mineral abundance), combined with numerical modelling suggests that up to 10 wt% assimilation of lithospheric mantle material has modified the compositions of the Kaavi-Kuopio kimberlites. These new data are also consistent with significant variations in the lithospheric mantle composition of the Karelian craton beneath the closely spaced (<10 km) kimberlites. Finally, in addition to mantle assimilation, formation of Si-Fe-rich mica in some of the examined kimberlites might be linked to late-stage increases in oxygen fugacity potentially enhanced by crustal contamination. This study shows for the first time that variable assimilation of mantle and crustal material can generate significant variations in kimberlites derived from seemingly similar sources.
DS202002-0174
2019
Phillips, D.Dalton, H., Giuliani, A., O'Brien, H., Phillips, D., Maas, R. Petrogenesis of a hybrid cluster of evolved kimberlites and ultramafic lamprophyres in the Kuusamo area, Finland. Kasma 45, Kasma 45 south, Kasma 47, Kalettomanpuro, Kattaisenvaara, Dike 15 and LampiJournal of Petrology, in press available, 79p. PdfEurope, Finlanddeposit - Kuusamo

Abstract: Kimberlites are often closely associated, both in time and space, with a wide variety of alkaline ultramafic rock types; yet the question of a genetic relationship between these rock types remains uncertain. One locality where these relationships can be studied within the same cluster is the Karelian craton in Finland. In this study we present the first petrographic, mineral and whole-rock geochemical results for the most recently discovered kimberlite cluster on this craton, which represents an example of the close spatial overlap of kimberlites with ultramafic lamprophyres. The Kuusamo cluster incorporates seven bodies (Kasma 45, Kasma 45 south, Kasma 47, Kalettomanpuro (KP), Kattaisenvaara (KV), Dike 15 and Lampi) distributed along a 60?km NE-SW corridor. Hypabyssal samples from KV, KP, Kasma 45 and Kasma 47 consist of altered olivine macrocrysts and microcrysts and phlogopite phenocrysts in a groundmass of perovskite, apatite, spinel, ilmenite, serpentine, and calcite. These petrographic features combined with mineral (e.g., Mg-rich ilmenite, Al-Ba-rich, Ti-Fe-poor mica) and whole-rock incompatible trace element compositions (La/Nb = 0.8 ± 0.1; Th/Nb = 0.07 ± 0.01; Nb/U = 66 ± 9) are consistent with these rocks being classified as archetypal kimberlites. These Kuusamo kimberlites are enriched in CaO and poor in MgO, which combined with the absence of chromite and paucity of olivine macrocrysts and mantle-derived xenocrysts (including diamonds), suggest derivation from differentiated magmas after crystal fractionation. Samples from Lampi share similar petrographic features, but contain mica with compositions ranging from kimberlitic (Ba-Al-rich cores) to those more typical of orangeites/lamproites (increasing Si-Fe, decreasing Al-Ti-Ba), and have higher bulk-rock SiO2 contents than the Kuusamo kimberlites. These features, combined with the occurrence of quartz and titanite in the groundmass, indicate derivation from a kimberlite magma that underwent considerable crustal contamination. This study shows that crustal contamination can modify kimberlites by introducing features typical of alkaline ultramafic rock types. Dike 15 represents a distinct carbonate-rich lithology dominated by phlogopite over olivine, with lesser amounts of titaniferous clinopyroxene and manganoan ilmenite. Phlogopite (Fe-Ti-rich) and spinel (high Fe2+/Fe2++Mg) compositions are also distinct from the other Kuusamo intrusions. The petrographic and geochemical features of Dike 15 are typical of ultramafic lamprophyres, specifically, aillikites. Rb-Sr dating of phlogopite in Dike 15 yields an age of 1178.8 ± 4.1?Ma (2?), which is considerably older than the ?750?Ma emplacement age of the Kuusamo kimberlites. This new age indicates significant temporal overlap with the Lentiira-Kuhmo-Kostomuksha olivine lamproites emplaced ?100?km to the southeast. It is suggested that asthenospheric aillikite magmas similar to Dike 15 evolved to compositions akin to the Karelian orangeites and olivine lamproites through interaction with and assimilation of MARID-like, enriched subcontinental lithospheric mantle. We conclude that the spatial coincidence of the Kuusamo kimberlites and Dike 15 is likely the result of exploitation of similar trans-lithospheric corridors.
DS202003-0366
2020
Phillips, D.Tovey, M., Giuliani, A., Phillips, D., Moss, S.Controls on the explosive emplacement of diamondiferous kimberlites: new insights from hypabyssal and pyroclastic units in the Diavik mine, Canada.Lithos, in press available, 55p. PdfCanada, Northwest Territoriesdeposit - Diavik

Abstract: Kimberlites are mantle-derived magmas that either crystallise as hypabyssal intrusions, erupt explosively after rapid ascent to the surface, or less commonly form lava lakes and flows, thereby creating texturally distinct kimberlite units. Efforts to fully understand the processes responsible for the explosive eruption of kimberlite magmas have been hindered by the widespread alteration and crustal contamination of most volcaniclastic kimberlites. To address this issue, we have undertaken a detailed petrographic and mineral chemical study of fresh (i.e. minimally altered) pyroclastic and hypabyssal kimberlites (HK) from the ca. 55-56?Ma A154 North and South kimberlite pipes in the Diavik Mine (Lac de Gras, Canada). These localities host exceptionally fresh kimberlites and are therefore ideally suited to this study. Kimberlite emplacement at A154 North and South initiated with the intrusion of hypabyssal kimberlite (external dykes), and was followed by the explosive formation of kimberlite pipes and volcaniclastic kimberlite infill. Subsequent kimberlite magmas intruded the volcaniclastic kimberlite units forming multiple cross-cutting, internal dykes. The studied volcaniclastic units feature abundant rounded magmaclasts and massive textures, suggestive of primary deposits. These units are classified as pyroclastic kimberlites (PK). Pyroclastic and hypabyssal kimberlite units at Diavik exhibit subtle mineral compositional differences. Samples from both internal HK units and PK units feature identical compositions for liquidus olivine rims (Mg#?=?90.5?±?0.1 and 90.7?±?0.2, respectively), with a marginally lower Mg# of 90.2?±?0.2 in olivine rims from the external HK dykes. Similarly, early-formed chromite compositions are the same for internal HK and PK units (Cr#?=?79.1?±?3.4 and 78.3?±?5.7; Mg#?=?60.0?±?1.3 and 60.0?±?2.2), but, differ in the external HK units (Cr#?=?86.9?±?2.7; Mg#?=?52.8?±?1.9). The internal HK and PK units also exhibit lower carbonate contents than the internal HK units. These compositional differences indicate that the external dykes were probably derived from slightly different primitive melt compositions to those parental to the internal HK and PK units. Spinel evolutionary trends from chromite to magnesian ulv?spinel-magnetite (MUM) compositions (Fe3+#?=?47.2?±?5.8 and 49.7?±?9.3; Cr#?=?25.7?±?11.0 and 17.0?±?14.0 for MUM) are indistinguishable in internal HK and PK samples. These results demonstrate that the primitive melt compositions and early magmatic evolution processes are identical for the internal kimberlite units, regardless of whether the kimberlite melts erupted explosively or were emplaced as shallow intrusions. However, magmaclasts in the PK units contain higher abundances of phlogopite (<52 vol%) and lower quantities of carbonate (<4 vol%) than the groundmass of the hypabyssal kimberlite samples (<2 vol% and 25-65 vol%, respectively). This indicates that the explosively erupted magmas featured higher H2O/CO2 ratios. In contrast, abundant carbonates, including dolomite, in the internal HK samples indicate that CO2, and therefore low H2O/CO2 ratios, were retained during the emplacement of this magma, which likely prevented phlogopite crystallisation. Lower K and Rb whole-rock compositions for internal HK samples compared to PK samples, are attributed to the removal of these components in late-stage kimberlitic fluids, as indicated by hydrothermal alteration of the adjacent volcaniclastic kimberlite units. The above results clearly rule out variations in primitive melt composition and melt evolution trajectories as a primary control on the explosive behaviour of the kimberlite magmas at Diavik. Our study also emphasises how volatile loss resulting from different emplacement styles can have a profound effect on the whole-rock compositions and petrography of kimberlite units. Controls on kimberlite explosivity at Diavik are likely due to external factors, such as local stress regimes, the availability of groundwater (i.e. phreatomagmatism) and differing magma supply rates.
DS202006-0950
2020
Phillips, D.Soltys, A., Giuliani, A., Phillips, D.Apatite compositions and groundmass mineralogy record divergent melt/fluid evolution trajectories in coherent kimberlites caused by differing emplacement mechanisms.Contributions to Mineralogy and Petrology, Vol. 175, 21p. PdfAfrica, South Africadeposit - Kimberley

Abstract: Kimberlites are pipe-like igneous bodies, consisting of a pyroclastic crater and diatreme, commonly underlain by coherent root-zone rocks, and with associated dyke/sill complexes. The processes that control the different modes of coherent kimberlite emplacement remain uncertain. In addition, late evolution of kimberlite melts during emplacement into the upper crust remains poorly constrained. Therefore, it is unclear whether there is a link between melt composition/evolution and the emplacement mechanism of coherent kimberlites (i.e. planar dykes/sills vs. irregular bodies in the root zone). An absence of comparative studies on late-stage magmatic phases across the different emplacement modes of coherent kimberlite from the same locality hamper resolution of these issues. Therefore, we report petrographic and mineral chemical data for groundmass apatite in samples of dyke, sill, and root-zone kimberlites from the Kimberley cluster (South Africa). Early crystallised phases (olivine, spinel, Mg-ilmenite) in dyke/sill and root-zone kimberlites have indistinguishable compositions, and hence crystallised from similar primitive melts. Conversely, apatite compositions are generally distinct in dyke/sill (low Sr, high and variable Si) and root-zone kimberlites (high and variable Sr, low Si). The Si enrichment of apatite in dykes/sills is attributed to the coupled incorporation of CO32? and SiO44? for PO43?, reflecting higher CO2 contents in their parental melts, and potentially higher Si contents due to the preferential crystallisation of carbonates over mica/monticellite. The low Sr contents of apatite in dyke/sill kimberlites reflect equilibrium with a (kimberlite) melt (i.e. DSr is close to unity for carbonate and silicate melts), whereas the higher Sr contents of apatite in root-zone kimberlites require crystallisation from, or overprinting by a H2O?±?CO2 fluid (significantly higher DSr). The relative enrichment of CO2 in kimberlite dykes/sills is evident from the abundance of carbonates, the presence of mesostasis dolomite and calcite phenocrysts in some samples, and concomitant reduced proportions of other groundmass phases (e.g. serpentine, mica, monticellite). During late alteration of kimberlite dykes/sills, monticellite is typically replaced by carbonates, whereas olivine and pleonaste are relatively stable, indicating the melts which form dykes/sills evolve to higher CO2/H2O ratios. It is unlikely that these two distinct evolutionary paths were caused by crustal contamination before or during near surface magma emplacement, because crustal assimilation is not recorded in the O and Sr isotopic composition of late crystallising olivine rinds or carbonates, respectively. We suggest that higher concentrations of CO2 are retained in kimberlite dykes/sills due to higher confining pressures (i.e. lack of breakthrough to the surface). In contrast, exsolution of CO2 from root-zone kimberlites increased melt H2O/CO2 ratios and promoted the crystallisation of mica and monticellite at the expense of dolomite and calcite. Apatite compositions have the potential to aid in the discrimination of kimberlites from lamproites (higher LREE, Sr, F, and S, lower Si contents) and carbonatites (higher LREE, F, Cl and S, lower Fe contents). However, the compositions of kimberlitic apatite overlap those from aillikites, probably due to similar late-stage melt compositions.
DS202007-1142
2020
Phillips, D.Giuliani, A., Pearson, D.G., Soltys, A., Dalton, H., Phillips, D., Foley, S.F., Lim, E.Kimberlite genesis from a common primary melt modified by lithospheric mantle assimilation.Science Advances, Vol. 6, eeaz0424Mantlemelting

Abstract: Quantifying the compositional evolution of mantle-derived melts from source to surface is fundamental for constraining the nature of primary melts and deep Earth composition. Despite abundant evidence for interaction between carbonate-rich melts, including diamondiferous kimberlites, and mantle wall rocks en route to surface, the effects of this interaction on melt compositions are poorly constrained. Here, we demonstrate a robust linear correlation between the Mg/Si ratios of kimberlites and their entrained mantle components and between Mg/Fe ratios of mantle-derived olivine cores and magmatic olivine rims in kimberlites worldwide. Combined with numerical modeling, these findings indicate that kimberlite melts with highly variable composition were broadly similar before lithosphere assimilation. This implies that kimberlites worldwide originated by partial melting of compositionally similar convective mantle sources under comparable physical conditions. We conclude that mantle assimilation markedly alters the major element composition of carbonate-rich melts and is a major process in the evolution of mantle-derived magmas.
DS202007-1179
2020
Phillips, D.Soltys, A., Giuliani, A., Phillips, D.Apatite compositions and groundmass mineralogy record divergent melt/fluid evolution trajectories in coherent kimberlites caused by differing emplacement mechanisms.Contributions to Mineralogy and Petrology, Vol. 175, 49 dor.org./10.1007 /s00410-020-01686-0Africa, South Africadeposit - Kimberley

Abstract: Kimberlites are pipe-like igneous bodies, consisting of a pyroclastic crater and diatreme, commonly underlain by coherent root-zone rocks, and with associated dyke/sill complexes. The processes that control the different modes of coherent kimberlite emplacement remain uncertain. In addition, late evolution of kimberlite melts during emplacement into the upper crust remains poorly constrained. Therefore, it is unclear whether there is a link between melt composition/evolution and the emplacement mechanism of coherent kimberlites (i.e. planar dykes/sills vs. irregular bodies in the root zone). An absence of comparative studies on late-stage magmatic phases across the different emplacement modes of coherent kimberlite from the same locality hamper resolution of these issues. Therefore, we report petrographic and mineral chemical data for groundmass apatite in samples of dyke, sill, and root-zone kimberlites from the Kimberley cluster (South Africa). Early crystallised phases (olivine, spinel, Mg-ilmenite) in dyke/sill and root-zone kimberlites have indistinguishable compositions, and hence crystallised from similar primitive melts. Conversely, apatite compositions are generally distinct in dyke/sill (low Sr, high and variable Si) and root-zone kimberlites (high and variable Sr, low Si). The Si enrichment of apatite in dykes/sills is attributed to the coupled incorporation of CO32? and SiO44? for PO43?, reflecting higher CO2 contents in their parental melts, and potentially higher Si contents due to the preferential crystallisation of carbonates over mica/monticellite. The low Sr contents of apatite in dyke/sill kimberlites reflect equilibrium with a (kimberlite) melt (i.e. DSr is close to unity for carbonate and silicate melts), whereas the higher Sr contents of apatite in root-zone kimberlites require crystallisation from, or overprinting by a H2O?±?CO2 fluid (significantly higher DSr). The relative enrichment of CO2 in kimberlite dykes/sills is evident from the abundance of carbonates, the presence of mesostasis dolomite and calcite phenocrysts in some samples, and concomitant reduced proportions of other groundmass phases (e.g. serpentine, mica, monticellite). During late alteration of kimberlite dykes/sills, monticellite is typically replaced by carbonates, whereas olivine and pleonaste are relatively stable, indicating the melts which form dykes/sills evolve to higher CO2/H2O ratios. It is unlikely that these two distinct evolutionary paths were caused by crustal contamination before or during near surface magma emplacement, because crustal assimilation is not recorded in the O and Sr isotopic composition of late crystallising olivine rinds or carbonates, respectively. We suggest that higher concentrations of CO2 are retained in kimberlite dykes/sills due to higher confining pressures (i.e. lack of breakthrough to the surface). In contrast, exsolution of CO2 from root-zone kimberlites increased melt H2O/CO2 ratios and promoted the crystallisation of mica and monticellite at the expense of dolomite and calcite. Apatite compositions have the potential to aid in the discrimination of kimberlites from lamproites (higher LREE, Sr, F, and S, lower Si contents) and carbonatites (higher LREE, F, Cl and S, lower Fe contents). However, the compositions of kimberlitic apatite overlap those from aillikites, probably due to similar late-stage melt compositions.
DS202008-1383
2020
Phillips, D.Dalton, H., Giuiani, A., Phillips, D., Hergt, J., Maas, R., Woodhead, J., Matchan, E., O'Brien, H.Kimberlite magmatism in Finland: distinct sources and links to the breakup of Rodinia.Goldschmidt 2020, 1p. AbstractEurope, Finlanddeposit - Kuusamo

Abstract: The Karelian Craton in Finland is host to (at least) two distinct pulses of kimberlite magmatism. Twenty kimberlite occurrences have so far been discovered on the southwest margin of the craton at Kaavi-Kuopio and seven kimberlites are located in the Kuusamo area within the core of the craton. Comprehensive radiometric age determinations (U-Pb, Ar- Ar and Rb-Sr) reveal that all kimberlite activity was restricted to the Proterozoic. The Kaavi-Kuopio field was emplaced over a protracted period from ~610 to 550 Ma and is predated by the Kuusamo cluster that represents a relatively short pulse of magmatism at ~750 to 730 Ma. The emplacement of kimberlites globally has recently been linked to supercontinent reorganisation and we propose a similar scenario for these Finnish occurrences which, at the time of kimberlite emplacement, were situated on the Baltica paleo-continent. This land mass was contiguous with Laurentia in the Proterozoic and together formed part of Rodinia. The breakup of Rodinia is considered to have commenced at ~750 Ma and initiation of the opening of the Iapetus ocean at ~615 Ma. Contemporaneous with Kaavi-Kuopio magmatism, this latter period of Neoproterozoic crustal extension also includes the emplacement of kimberlites and related rocks in areas that were linked with Baltica as part of Rodinia - West Greenland and eastern North America. Both the initial and final periods of Rodinia’s breakup have been linked to mantle upwellings from the core-mantle boundary. We suggest that kimberlite magmatism in Finland was promoted by the influx of heat from mantle upwellings and lithospheric extension associated with the demise of Rodinia. Although both magmatic episodes are potentially linked to the breakup of Rodinia, whole-rock and perovskite radiogenic isotope compositions for the Kuusamo kimberlites (?Nd(i) +2.6 to +3.3, ?Hf(i) +3.1 to +5.6) are distinct from the Kaavi-Kuopio kimberlites (?Nd(i) -0.7 to +1.8, ?Hf(i) -6.1 to +5.2). The spread in Hf isotope compositions for the Kaavi-Kuopio magmas may be linked to variable assimilation of diverse mantle lithologies.
DS202008-1452
2020
Phillips, D.Tovey, M., Giuliani, A., Phillips, D., Sarkar, C., Pearson, D.G., Nowicki, T., Carlson, J.Decoupling of kimberlite source and primitive melt compositions.Goldschmidt 2020, 1p. AbstractSouth America, Brazil, Africa, South Africa, Canada, Northwest Territoriesgeochronology

Abstract: Kimberlites emplaced since ~2 Ga show Nd and Hf isotopic compositions that follow a remarkably consistent linear evolution [1]. However, kimberlites emplaced <200 Ma within a few thousand kilometers of the western paleo-margin of Pangea (i.e. Brazil, southern Africa, and Lac de Gras in western Canada) deviate towards more enriched Nd and Hf isotopic compositions possibly due to contribution by recycled crustal material, introduced to the deep kimberlite source via subduction [1]. To address this anomaly further we have compared new and existing geochronological and Nd isotopic data for 28 kimberlites from Lac de Gras (LDG; ca. 47 - 75 Ma) with their olivine and spinel mineral chemistries. Olivine grains typically include mantle-derived xenocrystic cores (Mg# = 83.5-94.2) overgrown by magmatic rims with relatively constant Mg# values. Olivine rims and chromite are the first magmatic phases to crystallise from kimberlite and can be used as proxies for primitive melt compositions. The average Mg# of olivine cores from each kimberlite is positively correlated with average olivine rim Mg#, suggesting that assimilation of heterogeneous lithospheric mantle contributed to the primitive melt compositions. The ?Nd(i) values from whole-rock and perovskite from LDG kimberlites vary between -3.4 and -0.4 that are negatively correlated with their emplacement ages. This correlation is indicative of an evolving kimberlite source which may have resulted from a progressively lower contribution of recycled material. No systematic relationships were observed between olivine rim or chromite compositions and age or Nd isotopic composition. This observation highlights decoupling between kimberlite source evolution and primitive melt compositions due to the combined effects of crustal recycling in the kimberlite source and lithospheric mantle assimilation during kimberlite ascent.
DS202009-1664
2020
Phillips, D.Soltys, A., Giuliani, A., Phillips, D., Kamenetsky, V.S.Kimberlite metasomatism of the lithosphere and the evolution of olivine in carbonate rich melts - evidence from the Kimberley kimberlites ( South Africa).Journal of Petrology, in press available, 90p. PdfAfrica, South Africadeposit - Kimberley

Abstract: Olivine is the most abundant phase in kimberlites and is stable throughout most of the crystallization sequence, thus providing an extensive record of kimberlite petrogenesis. To better constrain the composition, evolution, and source of kimberlites we present a detailed petrographic and geochemical study of olivine from multiple dyke, sill, and root zone kimberlites in the Kimberley cluster (South Africa). Olivine grains in these kimberlites are zoned, with a central core, a rim overgrowth, and occasionally an external rind. Additional ‘internal’ and ‘transitional’ zones may occur between the core and rim, and some samples of root zone kimberlites contain a late generation of high-Mg olivine in cross-cutting veins. Olivine records widespread pre-ascent (proto-)kimberlite metasomatism in the mantle including the following features: (1) relatively Fe-rich (Mg# <89) olivine cores interpreted to derive from the disaggregation of kimberlite-related megacrysts (20?% of cores); (2) Mg-Ca-rich olivine cores (Mg# >89; >0•05?wt% CaO) suggested to be sourced from neoblasts in sheared peridotites (25?% of cores); (3) transitional zones between cores and rims probably formed by partial re-equilibration of xenocrysts (now cores) with a previous pulse of kimberlite melt (i.e. compositionally heterogeneous xenocrysts); (4) olivine from the Wesselton water tunnel sills, internal zones (I), and low-Mg# rims, which crystallized from a kimberlite melt that underwent olivine fractionation and stalled within the shallow lithospheric mantle. Magmatic crystallization begins with internal olivine zones (II), which are common but not ubiquitous in the Kimberley olivine. These zones are euhedral, contain rare inclusions of chromite, and have a higher Mg# (90•0 ± 0•5), NiO, and Cr2O3 contents, but are depleted in CaO compared with the rims. Internal olivine zones (II) are interpreted to crystallize from a primitive kimberlite melt during its ascent and transport of olivine toward the surface. Their compositions suggest assimilation of peridotitic material (particularly orthopyroxene) and potentially sulfides prior to or during crystallization. Comparison of internal zones (II) with liquidus olivine from other mantle-derived carbonate-bearing magmas (i.e. orangeites, ultramafic lamprophyres, melilitites) shows that low (100×) Mn/Fe (?1•2), very low Ca/Fe (?0•6), and moderate Ni/Mg ratios (?1•1) appear to be the hallmarks of olivine in melts derived from carbonate-bearing garnet-peridotite sources. Olivine rims display features indicative of magmatic crystallization, which are typical of olivine rims in kimberlites worldwide; that is, primary inclusions of chromite, Mg-ilmenite and rutile, homogeneous Mg# (88•8 ± 0•3), decreasing Ni and Cr, and increasing Ca and Mn. Rinds and high-Mg olivine are characterized by extreme Mg-Ca-Mn enrichment and Ni depletion, and textural relationships indicate that these zones represent replacement of pre-existing olivine, with some new crystallization of rinds. These zones probably precipitated from evolved, oxidized, and relatively low-temperature kimberlite fluids after crustal emplacement. In summary, this study demonstrates the utility of combined petrography and olivine geochemistry to trace the evolution of kimberlite magmatic systems from early metasomatism of the lithospheric mantle by (proto-)kimberlite melts, to crystallization at different depths en route to surface, and finally late-stage deuteric or hydrothermal fluid alteration after crustal emplacement.
DS202112-1943
2021
Phillips, D.Sarkar, S., Giuliani, A., Ghosh, S., Phillips, D.Petrogenesis of coeval lamproites and kimberlites from the Wajrakarur field, southern India: new insights from olivine compositions.Lithos, Vol. 406-407, 106524 13p. PdfIndiadeposit - Wajrakarur

Abstract: Olivine is one of the most abundant phases in kimberlites and cratonic lamproites, where it occurs as mantle-derived xenocrysts and magmatic phenocrysts or rims overgrowing xenocrystic cores, indicating its prevalence throughout most of the crystallisation sequence of these magmas. Thus, olivine can provide valuable insights into kimberlite and lamproite petrogenesis. Here, we present a detailed study of olivine compositional zoning in two lamproites (P2 and P12) of the Mesoproterozoic Wajrakarur kimberlite-lamproite field in southern India and use these data to propose a genetic link between lamproites and kimberlites in the region. Olivine macrocrysts (i.e., anhedral grains >1 mm) from the P2 and P12 intrusions are strongly zoned. Comparisons with olivine from mantle xenoliths worldwide demonstrate that the cores of olivine macrocrysts are xenocrysts derived from disaggregated mantle wall-rocks. The internal zones and overgrowth rims of olivine macrocrysts and the cores of olivine phenocrysts from P2 and P12 contain magmatic Mg-chromite and Ti-magnetite inclusions and hence crystallized from the host lamproite melt. These magmatic olivine zones show increasing Mg# (molar Mg/(Mg + Fe2+)), CaO and MnO contents with decreasing NiO. This reverse differentiation trend appears to be a characteristic feature of olivine in lamproites from the Wajrakarur field. To evaluate potential petrogenetic links between coeval lamproites and kimberlites from Wajrakarur, the composition of olivine xenocrysts (i.e., macrocryst cores) was compared with that of early crystallized olivine in P2, P12 and previously studied kimberlites and lamproites. The average Mg# of olivine macrocryst cores is directly correlated with the average Mg# of magmatic olivine in lamproites and kimberlites from Wajrakarur. Coupled with their indistinguishable Sr-Nd-Hf isotope compositions, these data suggest derivation of the Wajrakarur lamproites and kimberlites from a common source, The more Fe-rich composition of liquidus olivine in the Wajrakarur lamproites compared to coeval kimberlites suggests a higher degree of assimilation of metasomatised Fe-richer lithospheric mantle by the lamproites and provides a plausible explanation for the different petrological features of the Wajrakarur lamproites and kimberlites Our results suggest that cratonic lamproites can have a remarkably similar petrogenetic history to kimberlites.
DS202203-0336
2022
Phillips, D.Boone, S.C., Dalton, H., Prent, A., Kohlman, F., Theile, M., Greau, Y., Florin, G., Noble, W., Hodgekiss, S-A., Ware, B., Phillips, D., Kohn, B., O'Reilly, S., Gleadow, A., McInnes, B., Rawling, T.AusGeochem: an open platform for geochemical data preservation, dissemination and synthesis. Lithodat Pty *** not specific to diamonds but excellent concept/platformGeostandards and Geoanalysis Research, doi.org/10.1111/GGR.12419 34p. PdfAustraliageochemistry

Abstract: To promote a more efficient and transparent geochemistry data ecosystem, a consortium of Australian university research laboratories called the AuScope Geochemistry Network (AGN) assembled to build a collaborative platform for the express purpose of preserving, disseminating, and collating geochronology and isotopic data. In partnership with geoscience-data-solutions company Lithodat Pty Ltd, the open, cloud-based AusGeochem platform (https://ausgeochem.auscope.org.au) was developed to simultaneously serve as a geosample registry, a geochemical data repository, and a data analysis tool. Informed by method-specific groups of geochemistry experts and established international data reporting practices, community-agreed database schemas were developed for rock and mineral geosample metadata and secondary ion mass spectrometry U-Pb analysis, with additional models for laser ablation inductively-coupled mass spectrometry U-Pb and Lu-Hf, Ar-Ar, fission-track and (U-Th-Sm)/He under development. Collectively, the AusGeochem platform provides the geochemistry community with a new, dynamic resource to help facilitate FAIR (Findable, Accessible, Interoperable, Reusable) data management, streamline data dissemination and advanced quantitative investigations of Earth system processes. By systematically archiving detailed geochemical (meta-)data in structured schemas, intractably large datasets comprising thousands of analyses produced by numerous laboratories can be readily interrogated in novel and powerful ways. These include rapid derivation of inter-data relationships, facilitating on-the-fly data compilation, analysis, and visualisation.
DS202204-0521
2022
Phillips, D.Guiliani, A., Drysdale, R.N., Woodhead, J.D., Planavsky, N.J., Phillips, D., Hergt, J., Griffin, W.L., Oesch, S., Dalton, H., Davies, G.R.Pertubation of the deep-Earth carbon cycle in response to the Cambrian explosion.Science Advances, doi.10.1126/sciadv.abj1325 1p. PdfMantlesubduction

Abstract: Earth’s carbon cycle is strongly influenced by subduction of sedimentary material into the mantle. The composition of the sedimentary subduction flux has changed considerably over Earth’s history, but the impact of these changes on the mantle carbon cycle is unclear. Here, we show that the carbon isotopes of kimberlite magmas record a fundamental change in their deep-mantle source compositions during the Phanerozoic Eon. The 13C/12C of kimberlites before ~250 Ma preserves typical mantle values, whereas younger kimberlites exhibit lower and more variable ratios-a switch coincident with a recognized surge in kimberlite magmatism. We attribute these changes to increased deep subduction of organic carbon with low 13C/12C following the Cambrian Explosion when organic carbon deposition in marine sediments increased significantly. These observations demonstrate that biogeochemical processes at Earth’s surface have a profound influence on the deep mantle, revealing an integral link between the deep and shallow carbon cycles.
DS202205-0723
2022
Phillips, D.Tovey, M., Giuliani, A., Phillips, D., Nowicki, T., Pearson, D.G., Fedorchouk, Y., Russell, J.K.Controls on the emplacement style of coherent kimberlites in the Lac de Gras Field, Canada.Journal of Petrology, 10.1093/petrology/egac028/6553928 24p. pdf Canada, Northwest Territoriesdeposit - Lac de Gras

Abstract: In the Lac de Gras (LDG) kimberlite field, Northwest Territories, Canada, coherent kimberlites (CKs) occur as tabular dykes, pipe-shaped diatremes, and irregular bodies without well-defined geometries. Combining the morphology of CK bodies with the occurrence of fragmented olivine microcrysts allows distinction of four CK types at LDG: (1) dykes with no broken olivine; (2) CK without well-defined but probable sheet geometry and no broken olivine; (3) pipe-filling CK (pfCK) with abundant broken olivine and (4) pfCK with no broken olivine. These features suggest an intrusive origin for type 1 and, probably, type 2 CK; a high-energy extrusive emplacement for CK type 3 and a low-energy intrusive or extrusive emplacement for the CK type 4. Here, we compare petrographic and whole-rock, olivine and spinel compositional data for high-energy extrusive pfCK, low-energy pfCK and intrusive CK units to understand the factors controlling their variable emplacement styles. Extrusive CK contain more abundant groundmass phlogopite and monticellite, lower carbonate/silicate mineral abundance ratios and significantly lower dolomite and pleonaste-spinel abundances compared to intrusive CK. This indicates greater CO2 loss and higher H2O/CO2 in the melt phase for the extrusive CK during emplacement. Lower incompatible element concentrations in the extrusive CKs and different chromite Ti# and olivine rim Mg# indicate derivation from distinct primitive melt compositions. The extrusive CK feature higher ?Ndi and marginally higher ?Hfi compositions than the intrusive CK, pointing to derivation from distinct sources. These findings strongly imply that distinct primary melt compositions were largely responsible for the differences in emplacement styles of CK at LDG. Low-energy pfCKs have similar olivine rim Mg#, chromite Ti# and, hence, primitive melt compositions to the high-energy extrusive CK samples. Their marginally different emplacement styles may depend on local factors, such as changing stress regimes, or slightly different volatile concentrations. Both types of pfCK might reflect the waning stages of volcanic sequences resulting from the eruption of a segregated magma column that started with pipe excavation and the explosive emplacement of gas-rich magma (volcaniclastic kimberlite), followed by the less energetic emplacement of melt-rich magma (pfCK). This hypothesis underscores different primary melt compositions for dyke vs pipe-forming (and filling) kimberlites and hence a fundamental primary melt control on the explosivity of kimberlites.
DS1993-1234
1993
Phillips, D.C.Phillips, D.C.3-D geologic modeling.. no longer just a research toolGeotimes, Vol. 38, No. 7, July pp. 14-16GlobalGIS, Geologic modeling 3D.
DS1988-0268
1988
Phillips, D.S.Greiner, N.R., Phillips, D.S., Johnson, J.D., Volk, F.Diamonds in detonation sootNature, Vol. 333, No. 6172, June 2, pp. 440-441GlobalBlank
DS201610-1852
2010
Phillips, E.C.Chirico, P.G., Malpeti, K.C., Anum, S., Phillips, E.C.Alluvial diamond resource potential and production capacity assessment of Ghana.U.S. Geological Survey, Report 2010-5045, 25p.Africa, GhanaAlluvials, resources

Abstract: In May of 2000, a meeting was convened in Kimberley, South Africa, and attended by representatives of the diamond industry and leaders of African governments to develop a certification process intended to assure that rough, exported diamonds were free of conflictual concerns. This meeting was supported later in 2000 by the United Nations in a resolution adopted by the General Assembly. By 2002, the Kimberley Process Certification Scheme (KPCS) was ratified and signed by both diamond-producing and diamond-importing countries. Over 70 countries were included as members at the end of 2007. To prevent trade in "conflict" diamonds while protecting legitimate trade, the KPCS requires that each country set up an internal system of controls to prevent conflict diamonds from entering any imported or exported shipments of rough diamonds. Every diamond or diamond shipment must be accompanied by a Kimberley Process (KP) certificate and be contained in tamper-proof packaging. The objective of this study was to assess the alluvial diamond resource endowment and current production capacity of the alluvial diamond-mining sector in Ghana. A modified volume and grade methodology was used to estimate the remaining diamond reserves within the Birim and Bonsa diamond fields. The production capacity of the sector was estimated using a formulaic expression of the number of workers reported in the sector, their productivity, and the average grade of deposits mined. This study estimates that there are approximately 91,600,000 carats of alluvial diamonds remaining in both the Birim and Bonsa diamond fields: 89,000,000 carats in the Birim and 2,600,000 carats in the Bonsa. Production capacity is calculated to be 765,000 carats per year, based on the formula used and available data on the number of workers and worker productivity. Annual production is highly dependent on the international diamond market and prices, the numbers of seasonal workers actively mining in the sector, and environmental conditions, which influence seasonal farming.
DS200612-0381
2006
Phillips, E.R.Evans, D.J., Phillips, E.R., Hiemstra, J.F., Auton, C.A.Subglacial till: formation, sedimentary characteristics and classification.Earth Science Reviews, Vol. 78, 1-2, pp. 115-176.TechnologyClassification - not specific to diamonds
DS1860-1096
1899
Phillips, F. Lady.Phillips, F. Lady.Some South African RecollectionsLondon: Longmans Green And Co., Africa, South AfricaHistory
DS1991-1346
1991
Phillips, F.M.Phillips, F.M., Dorn, R.I.New methods for dating geomorphic surfaces.. Penrose Conference reportGsa Today, Vol. 1, No. 5, May p. 102GlobalGeomorphology, Age determinations
DS201912-2814
2019
Phillips, I.Phillips, I., Simister, R.L., Winterburn, P.A., Crowe, S.A.Microbial community fingerprinting as a tool for direct detection of buried kimberlites.Yellowknife Forum NWTgeoscience.ca, abstract volume p. 42-43.Canada, Northwest Territorieskimberlite

Abstract: Mineral exploration in northern latitudes is challenging in that undiscovered deposits are likely buried beneath significant glacial overburden. The development of innovative exploration strategies and robust techniques to see through cover is imperative to future discovery success. Microbial communities are sensitive to subtle environmental fluctuations, reflecting these changes on very short timescales. Shifts in microbial community profiles, induced by chemical differences related to geology, are detectable in the surficial environment, and can be used to vector toward discrete geological features. The modernization of genetic sequencing and big-data evaluation allows for efficient and cost-effective microbial characterization of soil profiles, with the potential to see through glacial cover. Results to date have demonstrated the viability of microbial fingerprinting to directly identify the surface projection of kimberlites in addition to entrained geochemical signatures in till. Soils above two kimberlites in the Northwest Territories, have undergone microbial community profiling. These community-genome derived datasets have been integrated with chemistry, mineralogy, surface geology, vegetation type and other environmental variables including Eh and pH. Analyses show significant microbial community shifts, correlated with the presence of kimberlites, with a distinct community response at the species level directly over known deposits. Diversity of soil bacteria is also depressed in the same regions of the microbial community response. The relationship between microbial profiles and buried kimberlites has led to the application of microbial fingerprinting as a method to accurately delineate potential ore deposits in covered terrain. The integration of microbial community information with soil chemistry and landscape development coupled with geology and geophysics significantly improves the drill / no-drill decision process and has proven to be far more accurate than traditional surficial exploration methods. There is high potential for application as a field-based technique as microbial databases for kimberlites in northern regions are refined, and as sequencing technology is progressively developed into portable platforms.
DS1859-0006
1684
Phillips, J.Tavernier, J.B., Phillips, J.The Six Voyages of John Baptiste Tavernier, a Noble Man of France, through Turkey Into Persia and the East Indies.Littlebury And Pitt., India, Turkey, IranTravelogue
DS201212-0554
2012
Phillips, J.Phillips, J.Storytelling in Earth Sciences: the eight basic plots.Earth Science Reviews, Vol. 115, 3, pp. 153-162.TechnologyHistory
DS1993-0621
1993
Phillips, J.C.Hallworth, M.A., Phillips, J.C., Huppert, H.E., Sparks, R.S.J.Entrainment in turbulent gravity currentsNature, Vol. 362, No. 6423, April 29, pp. 829-830GlobalSedimentation
DS200612-1505
2006
Phillips, J.C.Walters, A.L., Phillips, J.C., Brown, R.J., Field, M., Gernon, T., Stripp, G., Sparks, R.S.J.The role of fluidisation in the formation of volcaniclastic kimberlite: grain size observations and experimental investigation.Journal of Volcanology and Geothermal Research, in press availableAfrica, South AfricaDeposit - Venetia, explosive eruption, fluidization
DS202012-2212
2019
Phillips, J.C.Dupuy, D.C., Phillips, J.C.Selecting a diamond verification instrument based on the results of the Assure program: an initial analysis.Journal of Gemmology, Vol. 36, pp. 606-619.Globalluminescence

Abstract: Recently, the rapid growth in synthetic diamond production-particularly in melee sizes-and the salting of melee parcels with synthetics have generated a commensurate increase in the need for diamond verification instruments (DVIs). Ongoing independent third-party testing of these instruments is being done through the Assure Program. DVI performance is tested in a UL laboratory using carefully developed testing standards and sample sets (i.e. natural diamonds and as-grown and treated synthetics, as well as simulants as appropriate). The initial phase of testing was performed during latter 2018 and the first part of 2019, and as of July 2019 results for 16 widely available devices from 12 DVI manufacturers were published online in the Assure Directory (https://diamondproducers.com/assure/assure-directory). From these test results, the authors have evaluated several important parameters that will help users select the best instrument for their needs. Performance results from several additional DVIs are expected to be released in the near future, and further testing and publi-cation of the data will occur as new instruments are introduced and existing ones are updated.
DS1990-0271
1990
Phillips, J.D.Cannon, W.F., Phillips, J.D., Green, A.G., Morel-a l'Hussier, P.Great Lakes segment of the Canada -U.S. border transectGeological Society of America (GSA) Annual Meeting, Abstracts, Vol. 22, No. 7, p. A191GlobalGeochronology, Crust
DS1991-1347
1991
Phillips, J.D.Phillips, J.D., Reynolds, R.L., Frey, H.Crustal structure interpreted from magnetic anomalies. (review)Reviews of Geophysics, Vol. 29, No. S pp. 416-427MantleTectonics, Geophysics -magnetics
DS1993-1235
1993
Phillips, J.D.Phillips, J.D., Duval, J.S., Ambroziak, R.A.National geophysical dat a and topographic dat a for the conterminous USAUnited States Geological Survey (USGS), DDS-0009, 1 disc. $ 32.00United StatesGeophysics, CD-ROM datafile
DS202001-0008
2019
Phillips, J.G.Dupuy, H., Phillips, J.G.Selecting a diamond verification: instrument based on the results of the Assure program: an initial analysis.Journal of Gemmology, Vol. 36, 7, pp. 606-619.Globaldiamond identification
DS1996-0937
1996
Phillips, J.T.McMahon, B., Phillips, J.T., Hutton, W.A.The identification and elimination of the threat posed by a thickened tailings deposit in a seismic area.AusIMM Conference held March 24-26, Perth, pp. 37-45.AustraliaMineral processing -tailings, Deposit -Argyle
DS1992-1298
1992
Phillips, K.M.Roth, J.S., Phillips, K.M.The valuation debateAustralian Institute of Mining and Metallurgy (AusIMM) Bulletin, No. 3, May pp. 22-23GlobalGeostatistics, Ore reserves
DS1920-0191
1924
Phillips, L. SIR.Phillips, L. SIR.Some ReminiscencesLondon: Hutchinson., PP. 7-56.South AfricaBiography, Kimberley
DS1991-1348
1991
Phillips, O.M.Phillips, O.M.Flow and reactions in permeable rocksCambridge, 295p. approx. $ 60.00GlobalThermal convection, Ore deposits
DS200512-0853
2005
Phillips, P.Phillips, P.Ashton waltzes to centre stage in Quebec diamond play. Foxtrot property reveals large stones.Canadian Mining Journal, September, p.17-18.Canada, QuebecNews item - Ashton Mining
DS200712-0843
2007
Phillips, P.Phillips, P.The search for diamonds continues... exploration update by provinceDiamonds in Canada Magazine, Northern Miner, June pp. 6-8.CanadaExploration brief overview
DS200812-0894
2007
Phillips, P.Phillips, P.Rising to the challenge: hunting for diamonds (arctic) De Beers, Mountain Province, GGL, Diamondex, Peregrine, New Nadina, Sanatana, Indicator, Shear, SouthernEraDiamonds in Canada Magazine, Northern Miner, November pp. 11-15.Canada, Northwest Territories, NunavutNews item - brief overview
DS200812-0895
2007
Phillips, P.Phillips, P.Canada's sparkling gems: Ekati, Diavik and Jericho.Diamonds in Canada Magazine, Northern Miner, November pp. 4-6.Canada, Northwest Territories, NunavutNews item - brief overview
DS1970-0581
1972
Phillips, R.Phillips, R.A New Method for Estimating the Grade of Diamond DepositsInstitute of Mining and Metallurgy. SPECIAL Publishing GEOLOGICAL SAMPLING IN THE MIN, PP. 20-25.Southwest Africa, NamibiaSampling, Evaluation, Mining Diamond, Alluvial Placers
DS2000-0764
2000
Phillips, R.Phillips, R.Reporting on mineral resources and ore reserves- a note on legal liabilityMin. Res. Ore Res. Est. AusIMM Guide, Mon. 23, pp. 677-82.AustraliaEconomics - geostatistics, ore reserves, exploration, Not specific to diamonds
DS2001-0917
2001
Phillips, R.Phillips, R.Liability issues for valuation practitioners: recent development in Australian lawValmin 01, Mineral Asset Valuation Oct. 25-6th., pp.93-113.AustraliaEconomics - legal code, Mineral reserves, resources, valuation, exploration
DS1986-0643
1986
Phillips, R.J.Phillips, R.J.Constraints on lithospheric structure from satellite potential field at:Africa and Asia. Analysis and interpretation of Magsat anomalies over NorthAfricaNational Technical Information Service, No. N86-21968/0 104pAfrica, AsiaGeophysics
DS2000-0112
2000
Phillips, R.J.Brown, C.D., Phillips, R.J.Crust mantle decoupling by flexure of continental lithosphereJournal of Geophysical Research, Vol. 105, No. 6, June 10, pp. 13221-MantleGeophysics - seismics, Decoupling
DS201112-0997
2011
Phillips, S.Steck, L.K., Behnaud, M.L., Phillips, S., Stead, R.Tomography of crustal P and S travel times across the western United States.Journal of Geophysical Research, Vol. 116, no. B 11, B11304.United StatesGeophysics - seismics
DS1859-0109
1852
Phillips, W.Phillips, W.An Elementary Introduction to MineralogyLondon: Longman, Brown, Green And Longmans, 700P. SECOND EDITION.United States, Georgia, North Carolina, AppalachiaMineralogy
DS1910-0082
1910
Phillips, W.B.Phillips, W.B.Precious Stones in Texas (1910)Jewellers Circular Keystone, Vol. 61, No. 15, Nov. 9TH. P. 89.United States, Texas, Gulf CoastBlank
DS1970-0805
1973
Phillips, W.J.Phillips, W.J.Mechanical Effects of Retrograde Boiling and its Probable Importance in the Formation of Some Porphyry Ore Deposits.Institute of Mining and Metallurgy. Transactions, Vol. 82, PP. B90-98; Vol. 83, PP. B42-43.GlobalBreccia
DS1985-0528
1985
Phillips, W.J.Phillips, W.J.Report on a Joint Meeting on Placer Deposits Organized by The Institution of Mining and Metallurgy and the British Geomorphological Research Group. Held November 14, 1984.Institute of Mining and Metallurgy. Transactions, Vol. 94, SECT. B, PP. B46-48.West Africa, Sierra Leone, East Africa, SwazilandBlank
DS201610-1897
2016
Phillips, W.R.Phillips, W.R., Shigley, J.Understanding the gem minerals. A practical guide. Basic concepts on both mineralogy and geology.Mineralogical Association of Canada, Special Publications no. 12, 272p. ISBN 978-0-921294-58-0 approx. 70.00Gem minerals

Abstract: Gemstones have fascinated people for thousands of years because of their beauty, rarity, and monetary value. However, a true understanding of gemstones and their properties has only come about in the past two centuries resulting from the developing science of geology and mineralogy and an increasing need to distinguish natural gemstones from those that are treated or grown in the laboratory. Numerous books describe minerals, and a number of them report on the distinctive properties of gemstones, but there are almost no books that present a more detailed mineralogical description of the gem minerals, along with a clear explanation of basic concepts of interest from both mineralogy and geology.
DS1998-1161
1998
Philpott, P.Philpott, P., Agrinier, ScambelluriChlorine cycling during subduction of altered oceanic crustMineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 1169-70.MantleSubducion, Volatiles
DS1999-0553
1999
Philpott, P.Perchuk, A., Philpott, P., Erdmer, P., Filian, M.Rates of thermal equilibrium at the onset of subduction deduced from diffusion modeling of eclogitic garnets...Geology, Vol. 27, No. 6, June, pp. 531-4.YukonTanan Terrane - not specific to diamonds, Garnets - eclogites
DS1960-0809
1967
Philpotts, A.R.Clark, T.H., Kranck, E.H., Philpotts, A.R.Ile Ronde Breccia, MontrealCanadian Journal of Earth Sciences, Vol. 4, PP. 507-513.Canada, QuebecBlank
DS1970-0976
1974
Philpotts, A.R.Philpotts, A.R.The Montregian ProvinceIn: The Alkaline Rocks, Sorenson, H. Ed., PP. 293-310.Canada, QuebecRelated Rocks
DS1991-1349
1991
Philpotts, A.R.Philpotts, A.R.Proposed origin for the older White Mountain magma series, New HampshireGeological Society of America Abstracts, Northeastern section, March 14-16th., Vol. 23, No. 1, February p. 115GlobalHot spots, Alkaline rocks
DS200712-0844
2007
Philpotts, A.R.Philpotts, A.R., Philpotts, D.E.Upward and downward flow in a camptonite dike as revealed by deformed vesicles and the anisotropy of magnetic susceptibility AMS.Journal of Volcanology and Geothermal Research, Vol. 161, 1-2, pp. 81-94.TechnologyCamptonite
DS200712-0844
2007
Philpotts, D.E.Philpotts, A.R., Philpotts, D.E.Upward and downward flow in a camptonite dike as revealed by deformed vesicles and the anisotropy of magnetic susceptibility AMS.Journal of Volcanology and Geothermal Research, Vol. 161, 1-2, pp. 81-94.TechnologyCamptonite
DS1991-1350
1991
Philpotts, J.Philpotts, J., Tatsumoto, M., Xianhua Li, Kaiyi WangSome neodymium and Strontium isotopic systematics for the rare earth elements (REE) enriched deposit at Bayan Obo, ChinaChemical Geology, Vol. 90, pp. 177-188ChinaGeochronology, rare earth elements (REE)., Carbonatite
DS1970-0582
1972
Philpotts, J.A.Philpotts, J.A., Schnetzler, C.C., Thomas, H.H.Petrogenetic Implications of Some New Geochemical Dat a on Eclogitic and Ultrabasic Inclusions.Geochimica Et Cosmochimica Acta, Vol. 36, No. 10, PP. 1131-1166.South AfricaPetrology, Geochemistry
DS1985-0529
1985
Philpotts, J.A.Philpotts, J.A.Rare Earth Concentrations in Igneous Rocks and OresIn: Conference on Rare earths Devel. Applications, Vol. 1, pp. 53-56GlobalRare Earths, Carbonatite
DS1995-0207
1995
PhinneyBrenan, J.M., Shaw, H.F., Ryerson, PhinneyMineral aequeous fluid partitioning of trace elements at 900 and 2.0 GPa:constraints - chemistry....Geochimica et Cosmochimica Acta, Vol. 59, No. 16, pp. 3331-50.MantleMineral chemistry, Deep crustal fluids
DS201112-0133
2011
Phinney, D.Caciagli, N., Brenan, J.M., McDonough, W.F., Phinney, D.Mineral fluid partitioning of lithium and implications for slab-mantle interaction.Chemical Geology, Vol. 280, 3-4, pp. 384-398.MantleGeochemistry
DS1995-0206
1995
Phinney, D.L.Brenan, J.M., Shaw, H.F., Phinney, D.L.Mineral aequeous fluid partitioning of trace elements at 900C 2.0 GPa:constraints on trace elements -mantleGeochimica et Cosmochimica Acta, Vol. 59, No. 16, August 1, pp. 3331-50MantleGeochemistry
DS1989-1211
1989
Phinney, W.C.Phinney, W.C., Morrison, D.A., Maczuga, D.E.Anorthosites and related megacrystic units in the evolution of ArcheancrustJournal of Petrology, Vol. 29, No. 6, pp. 1283-1323. Database # 17977Ontario, Greenland, South AfricaAnorthosites -chromite, Archean
DS1990-1098
1990
Phinney, W.C.Nelson, D.O., Morrison, D.A., Phinney, W.C.Open system evolution versus source control in basaltic magmas:Matachewan-Hearst dike swarm, Superior Province, CanadaCanadian Journal of Earth Sciences, Vol. 27, No. 6, June pp. 767-783OntarioMatachewan dikes, Basaltic magmas
DS1992-1193
1992
Phinney, W.C.Phinney, W.C.Geochemical constraints on the petrogenesis of the Matachewan dike swarmOntario: implications for a plume originProceedings of the 29th International Geological Congress. Held Japan August 1992, Vol. 2, abstract p. 566OntarioDike swarm, Geochemistry
DS2001-0918
2001
Phinney, W.C.Phinney, W.C., Halls, H.C.Petrogenesis of the Early Proterozoic Matachewan dike swarm: implications for magma emplacement and deform.Canadian Journal of Earth Science, Vol. 38, No. 11, Nov. pp. 1541-63.OntarioMagmatism, Dyke Swarm - Matachewan
DS1983-0516
1983
Phipps, S.P.Phipps, S.P.Structural Style of Ancestral Rocky Deformation Midcontinent Region, UsaGeological Society of America (GSA), Vol. 15, No. 6, P. 661 (abstract.).GlobalMid Continent
DS200412-1543
2004
Phipps Morgan, J.Phipps Morgan, J., Reston, T.J., Ranero, C.R.Contemporaneous mass extinctions, continental flood basalts, and impact signals are mantle plume induced lithospheric gas explosEarth and Planetary Science Letters, Vol. 217, 3, Jan. 15, pp. 263-284.MantlePlume
DS200912-0450
2008
Phipps Morgan, J.Long, A.M., Phipps Morgan, J.Implications of the kinked Boyd kimberlite geotherm for the thermal evolution beneath continents.American Geological Union, Fall meeting Dec. 15-19, Eos Trans. Vol. 89, no. 53, meeting supplement, 1p. abstractMantleGeothermometry
DS1860-0052
1867
PhipsonPhipsonSur la Presence du Diamant dans Les Sables Metalliferes de Fremantle (australie Ouest).Comptes Rendu , Vol. 64, PP. 87-88.Australia, Western AustraliaDiamond Occurrence
DS200412-1544
2003
Phoenix Matachewan Mines Inc.Phoenix Matachewan Mines Inc.Argyle geophysical survey initiated. Argyle property IP and Mag survey.Phoenix Matachewan Mines Inc., Dec. 9, 1p.Canada, OntarioNews item - press release
DS1985-0629
1985
Phofuetsile, P.Smith, R.A., Phofuetsile, P.The geology of the Foley area ( an explanation of Quarter degree Sheet2127C)Botswana Geological Survey, Bulletin. No. 31, 107p. mapBotswanaMotloutse River Area, Alluvials
DS1991-1351
1991
Phoon, V.S.O.Phoon, V.S.O., Williams, T.Problems of testing gravity seperation plants used in alluvial miningAlluvial Mining, Institute of Mining and Metallurgy (IMM) Special Volume, pp. 371-421GlobalAlluvial mining, Placer calculations - not specific to diamonds
DS201412-0688
2014
Phosiwa, A.Phosiwa, A.Metallurgical development of alluvial diamond processing.GSSA Kimberley Diamond Symposium and Trade Show provisional programme, Sept. 10-12, POSTERTechnologyMetallugy
DS1970-0267
1971
Phukan, S.Das gupta, S.P., Phukan, S.Mineralogy of the Altered Diamondiferous Pipe Rock at Panna, M.p.India Geological Survey Miscellaneous Publishing, No. 19, PP. 114-119.India, Madhya PradeshProspecting, Mineralogy
DS1970-0381
1971
Phukan, S.Phukan, S.Inclusions in the Panna Diamonds of IndiaJournal of Gemology, Vol. 12, No. 5, PP. 157-170.IndiaMineralogy
DS1970-0382
1971
Phukan, S.Phukan, S.Methods of Identification of DiamondsIndia Geological Survey Miscellaneous Publishing, No. 19, PP. 134-140.IndiaMineralogy, Criteria, Natural Diamonds, Morphology
DS201910-2291
2019
Phys.orgPhys.orgFirst direct evidence for a mantle plume origin of Jurassic flood basalts in southern Africa. SummaryPhys.org.com, Aug. 26, 2p.Africa, Mozambiquepicrites

Abstract: A group of geochemists suggests they have found the smoking gun in the Karoo magma province. Their new article reports the discovery of primitive picrite lavas that may provide the first direct sample of a hot mantle plume underneath southern Africa in the Jurassic period.
DS200512-0816
2002
Pia Cid, J.Paim, M.M., Pia Cid, J., Rosa, M.L.S., Conceicao, H., Nardi, L.V.S.Mineralogy of lamprophyres and mafic enclaves associated with the Paleoproterozoic Cara Suja syenite, northeast Brazil.International Geology Review, Vol. 44, Nov. 11, pp. 1017-1036.South America, BrazilLamprophyre
DS202010-1866
2020
Piani, L.Piani, L., Marrocchi, Y., Rigaudier, T.Earth's water may have been inherited from material similar to enstatite chondrite metorites.Science, Vol. 369, 6507, pp. 110-1113. doi. 10.1126/ science.aba.1948Mantlewater

Abstract: The abundances of Earth's chemical elements and their isotopic ratios can indicate which materials formed Earth. Enstatite chondrite (EC) meteorites provide a good isotopic match for many elements but are expected to contain no water because they formed in the hot inner Solar System. This would require Earth's water to be from a different source, such as comets. Piani et al. measured hydrogen contents and deuterium/hydrogen ratios (D/H) in 13 EC meteorites (see the Perspective by Peslier). They found far more hydrogen than is commonly assumed, with D/H close to that of Earth's mantle. Combining these data with cosmochemical models, they show that most of Earth's water could have formed from hydrogen delivered by EC meteorites.
DS1997-0816
1997
Pianosi, S.Morris, T.F., Crabtree, D., Pianosi, S.Results of modern alluvium sampling for kimberlite indicator minerals, Kinniwabi Lake area, northwest Ontario.Ontario Geological Survey Open File, No. 5956 Digital data MRD 23 $ 9.00OntarioSampling, Geochemistry
DS200412-1545
2004
Pians Agostinni, N.Pians Agostinni, N., Spada, G., Cianetti, S.Mantle viscosity inference: a comparison between simulated annealing and neighbourhood algorithm inversion methods.Geophysical Journal International, Vol. 157, 2, pp. 890-900.MantleGeophysics
DS1993-0886
1993
Piantone, P.Laval, M., Piantone, P., Freyssinet, Ph., Kosakevitch, A.Role of florencite and pyrochlore in the behaviour of rare earth elements (REE) duringlaterisation: example of Mabounie carbonatite (Gabon)Terra Abstracts, IAGOD International Symposium on mineralization related to mafic, Vol. 5, No. 3, abstract supplement p. 25GlobalCarbonatite
DS1995-1495
1995
Piantone, P.Piantone, P., Itard, Y., et al.Compositional variation in pyrochlores from the weathered Mabouniecarbonatite.Sga Third Biennial Meeting, Aug. 1995, pp. 629-632.GlobalCarbonatite, Deposit -Mabounie
DS201412-0006
2014
Piasecki, A.Alvarez-Valero, A.M., Jagoutz, O., Stanley, J., Manthei, C., Ali Moukadiri, A., Piasecki, A.Crustal attenuation as a tracer for the emplacement of the Beni Bousera ultramafic massif ( Betico-Rifean belt).Geological Society of America Bulletin, Vol. 126, no. 11/12, pp. 1614-1624.Africa, MoroccoBeniBoussera
DS201709-2003
2017
Piazoli, S.Jacob, D.E., Stern, R.A., Chapman, J., Piazoli, S.Insights into diamond formation from polycrystalline diamond aggregates. DiamonditesGoldschmidt Conference, abstract 1p.Africa, South Africadeposit - Venetia

Abstract: Polycrystalline diamond aggregates (diamondites) are produced by rapid crystal nucleation caused by extreme carbon supersaturation in mantle fluids. They may form episodically and under variable chemical conditions, providing snapshots of diamond formation in the Earth’s mantle. Diamondites, thus, represent an extreme end member of diamond formation mechanisms, while forming via the same processes and ingredients as the gem-sized diamonds. We present results on a large suite of diamondites from the Venetia mine (South Africa), comprising a complete characterisation of the diamonds and their silicate inclusions and intergrowths. The highlighted characteristic of this sample suite is its heterogeneity in all aspects, from affiliated silicate to diamond composition and texture of the diamond aggregates. The diamond grains in the samples are intergrown with silicates (garnets, clinopyroxenes, phlogopites) comprising a websteritic-eclogitic and a peridotiticpyroxenitic suite of minerals. Diamonds, regardless of their affiliation based on their silicate phases, overlap in carbon and nitrogen composition and have ?13C values between -28 and -8 ‰, ?15N values of 0.8 to 16.3 ‰ and nitrogen contents of 4 to 2329 ppm. The entire range of carbon and nitrogen variability of the suite is also reflected in some individual samples. Cathodoluminescence imaging visualizes different zones in the samples that can be interpreted as different growth events with differing nitrogen contents and ?15N decoupled from ?13C values, in line with the variability off nitrogen aggregation states. Electron backscatter diffraction analyses identify an original texture of randomly intergrown diamond grains that is partly changed by deformation and newly grown smaller diamond grains. The large overall variability suggesting episodic formation of diamondite with nitrogen from crustal sources.
DS201112-0454
2011
PiazoloHowell, D., Griffin, W.L., O'Reilly, S.Y., O'Neill, C., Pearson, N., Piazolo, Stachel, Stern, NasdalaMixed habit diamonds: evidence of a specific mantle fluid chemistry?Goldschmidt Conference 2011, abstract p.1051.TechnologyDiamond morphology, growth
DS201212-0311
2012
Piazolo, S.Howell, D., Piazolo, S., Dobson, D.P., Wood, I.G., Jones, A.P., Watte, N., Frost, D.J., Fisher, D., Griffin, W.L.Quantitative characterization of plastic deformation of single diamond crystals: a high pressure high temperature (HPHT) experimental deformation study combines with electron backscatter diffraction.Diamond and Related Materials, Vol. 30, pp. 20-30.TechnologyDiamond morphology
DS201508-0359
2015
Piazolo, S.Howell, D., Fisher, D., Piazolo, S., Griffin, W.L., Sibley, S.J.Pink color in Type I diamonds: is deformation twinning the cause?American Mineralogist, Vol. 100, pp. 1518-1527.Australia, South America, VenezuelaDeposit - Argyle, Santa Elena
DS201606-1102
2016
Piazolo, S.Kvassnytsya, V., Wirth, R., Piazolo, S., Jacob, D.E., Trimby, P.Surface morphology and structural types of natural impact apographitic diamonds. IN RUSSIANSverkhtverdie Materiali ( Ukraine) in RUSSIAN, No. 2, pp. 3-17.TechnologyMorphology of lonsdaleite, diamond

Abstract: External and internal morphologies of natural impact apographitic diamonds (paramorphoses) have been studied. The (0001) surface morphology of the paramorphoses reflects their phase composition and the structural relationship of its constituting phases. Growth and etch figures together with the elements of crystal symmetry of lonsdaleite and diamond are developed on these surfaces. The crystal size of lonsdaleite is up to 100 nm, and that of diamond is up to 300 nm. Two types of structural relations between graphite, lonsdaleite, and diamond in the paramorphoses are observed: the first type (black, black-gray, colorless and yellowish paramorphoses): the (0001) graphite face is parallel to the (100) lonsdaleite face and parallel to (111) diamond; the second type (milky-white paramorphoses): the (0001) graphite is parallel to the (100) lonsdaleite and parallel to the (112) diamond. The first type of the paramorphoses contains lonsdaleite, diamond, graphite or diamond, lonsdaleite, the second type of the paramorphoses contains predominantly diamond. The direct phase transition of graphite ? lonsdaleite and/or graphite ?diamond occurred in the paramorphoses of the first type. A successive phase transition graphite ? lonsdaleite ? diamond was observed in the paramorphoses of the second type. The structure of the paramorphoses of this type shows characteristic features of recrystallization.
DS201607-1303
2016
Piazolo, S.Jacob, D.E., Piazolo, S., Screiber, A., Trimby, P.Redox-freezing and nucleation of diamond via magnetite formation in the Earth's mantle.Nature Communications, Vol. 7, June 21, 7p.Africa, BotswanaDeposit - Orapa

Abstract: Diamonds and their inclusions are unique probes into the deep Earth, tracking the deep carbon cycle to >800?km. Understanding the mechanisms of carbon mobilization and freezing is a prerequisite for quantifying the fluxes of carbon in the deep Earth. Here we show direct evidence for the formation of diamond by redox reactions involving FeNi sulfides. Transmission Kikuchi Diffraction identifies an arrested redox reaction from pyrrhotite to magnetite included in diamond. The magnetite corona shows coherent epitaxy with relict pyrrhotite and diamond, indicating that diamond nucleated on magnetite. Furthermore, structures inherited from h-Fe3O4 define a phase transformation at depths of 320 -330?km, the base of the Kaapvaal lithosphere. The oxidation of pyrrhotite to magnetite is an important trigger of diamond precipitation in the upper mantle, explaining the presence of these phases in diamonds.
DS201610-1898
2016
Piazolo, S.Piazolo, S., Kaminsky, F.V., Trimby, P., Evans, L., Luzin, V.Carbonado revisited: insights from neutron diffraction, high resolution orientation mapping and numerical simulations.Lithos, in press available 13p.TechnologyCarbonado

Abstract: One of the most controversial diamond types is carbonado, as its origin and geological history are still under debate. Here, we investigate selected carbonado samples using neutron diffraction and high resolution orientation mapping in combination with numerical simulations. Neutron diffraction analyses show that fine grained carbonado samples exhibit a distinct lack of crystallographic preferred orientation. Quantitative crystallographic orientation analyses performed on transmission electron microscope (TEM) sections reveal that the 2-10 ?m grains exhibit locally significant internal deformation. Such features are consistent with crystal plastic deformation of a grain aggregate that initially formed by rapid nucleation, characterized by a high number of nucleation sites and no crystallographic preferred orientation. Crystal plastic deformation resulted in high stress heterogeneities close to grain boundaries, even at low bulk strains, inducing a high degree of lattice distortion without significant grain size reduction and the development of a crystallographic preferred orientation. Observed differences in the character of the grain boundary network and internal deformation structures can be explained by significant post-deformation annealing occurring to variable degrees in the carbonado samples. Differences in intensity of crystal bending and subgrain boundary sharpness can be explained by dislocation annihilation and rearrangement, respectively. During annealing grain energy is reduced resulting in distinct changes to the grain boundary geometry. Grain scale numerical modelling shows that anisotropic grain growth, where grain boundary energy is determined by the orientation of a boundary segment relative to the crystallographic orientation of adjacent grains results in straight boundary segments with abrupt changes in orientation even if the boundary is occurring between two triple junctions forming a "zigzag" pattern. In addition, in diamond anisotropic grain growth results in triple junctions that rarely show 120° angles. Our results support the interpretation that carbonados may have undergone at least 2 or 3 stages of development with rapid nucleation, crystal plastic deformation to low strains and variable degrees of post-deformation annealing. Such a history is commonly observed in Earth's crustal or mantle rocks. Hence, for carbonados it is not necessary to invoke an extraordinary and/or extraterrestrial origin and history. The combination of methods utilized here, promises to help advance our understanding of diamond and diamond aggregates in the future.
DS201701-0025
2016
Piazolo, S.Piazolo, S., Kaminsky, F.V., Trimby, P., Evans, L., Luzin, V.Carbonado revisited: insights from neutron diffraction, high resolution orientation mapping and numerical simulations.Lithos, in press available 13p.TechnologyCarbonado

Abstract: One of the most controversial diamond types is carbonado, as its origin and geological history are still under debate. Here, we investigate selected carbonado samples using neutron diffraction and high resolution orientation mapping in combination with numerical simulations. Neutron diffraction analyses show that fine grained carbonado samples exhibit a distinct lack of crystallographic preferred orientation. Quantitative crystallographic orientation analyses performed on transmission electron microscope (TEM) sections reveal that the 2-10 ?m grains exhibit locally significant internal deformation. Such features are consistent with crystal plastic deformation of a grain aggregate that initially formed by rapid nucleation, characterized by a high number of nucleation sites and no crystallographic preferred orientation. Crystal plastic deformation resulted in high stress heterogeneities close to grain boundaries, even at low bulk strains, inducing a high degree of lattice distortion without significant grain size reduction and the development of a crystallographic preferred orientation. Observed differences in the character of the grain boundary network and internal deformation structures can be explained by significant post-deformation annealing occurring to variable degrees in the carbonado samples. Differences in intensity of crystal bending and subgrain boundary sharpness can be explained by dislocation annihilation and rearrangement, respectively. During annealing grain energy is reduced resulting in distinct changes to the grain boundary geometry. Grain scale numerical modelling shows that anisotropic grain growth, where grain boundary energy is determined by the orientation of a boundary segment relative to the crystallographic orientation of adjacent grains results in straight boundary segments with abrupt changes in orientation even if the boundary is occurring between two triple junctions forming a “zigzag” pattern. In addition, in diamond anisotropic grain growth results in triple junctions that rarely show 120° angles. Our results support the interpretation that carbonados may have undergone at least 2 or 3 stages of development with rapid nucleation, crystal plastic deformation to low strains and variable degrees of post-deformation annealing. Such a history is commonly observed in Earth's crustal or mantle rocks. Hence, for carbonados it is not necessary to invoke an extraordinary and/or extraterrestrial origin and history. The combination of methods utilized here, promises to help advance our understanding of diamond and diamond aggregates in the future.
DS201701-0035
2016
Piazolo, S.Tretiakova, I.G., Belousova, E.A., Malkovets, V.G., Griffin, W.L., Piazolo, S., Pearson, N.J., O'Reilly, S.Y., Nishido, H.Recurrent magmatic activity on a lithosphere scale structure: crystallization and deformation in kimberlitic zircons.Gondwana Research, Vol. 42, pp. 126-132.RussiaDeposit - Nubinskaya

Abstract: Kimberlites are not only the most economically important source of diamonds; they also carry unique information encapsulated in rock fragments entrained as the magma traverses the whole thickness of the lithosphere. The Nurbinskaya pipe in the Siberian kimberlite province (Russia) is one of several intruded along the Vilyui Rift, a major terrane boundary. The pipe contains three populations of mantle-derived zircon xenocrysts: Archean (mean age 2709 ± 9 Ma), Devonian (mean age 371 ± 2.3 Ma), and a subset of grains with evidence of brittle deformation and rehealing, and a range of ages between 370 and 450 Ma. The Hf-isotope, O-isotope and trace-element signatures of the last group provide a link between the Archean and Devonian events, indicating at least three episodes of magmatic activity and zircon crystallization in the lithosphere beneath the pipe. The emplacement of the Nurbinskaya pipe ca 370 Ma ago was only the youngest activity in a magma plumbing system that has been periodically reactivated over at least 2.7 billion years, controlled by the lithosphere-scale structure of the Vilyui Rift.
DS201809-2044
2018
Piazolo, S.Jacob, D.E., Stern, R.A., Stachel, T., Piazolo, S.Polycrystalline diamonds and their mantle derived mineral and fluid intergrowths. (Aggregates, framesites, boart, diamondite)Goldschmidt Conference, 1p. AbstractAfrica, South Africadeposit - Venetia

Abstract: Polycrystalline diamond aggregates (framesites, boart, diamondite) are an understudied variety of mantle diamond, but can make up 20% of the production in some Group I kimberlites. Their polycrystalline nature indicates rapid precipitation from carbon-oversaturated fluids and individual PDAs often contain a chemically heterogeneous suite of websteritic and pyroxenitic inclusions and minerals intimately intergrown with the diamond crystals. Geochemical and microstructural evidence suggests that fluid-driven redox reactions with lithospheric material occurring episodically over millions of years play a major role in freezing carbon in the subcratonic lithosphere (Jacob et al., 2000; 2016; Mikhail et al., 2014). A suite of 39 samples from the Venetia kimberlite pipe in South Africa allows a more detailed look at the diamondforming fluids. 13C values in the diamonds measured by secondary ion mass spectrometry range from +2 to -28 and cover the entire range for PDA from the literature. Nitrogen concentrations are mostly very low (less than 100 at ppm), but reach up to 2660 at ppm in individual samples. These high nitrogen concentrations in concert with mostly positive 15N values of up to +17 and some very negative 3C values suggest crustal material as the source of the nitrogen and the carbon. However, detailed analysis of the sample provides evidence for a more complex growth history followed by alteration. Individual diamond crystals show complex growth zonations by cathodoluminescence imaging that can be related with the carbon and nitrogen isotopic compositions and points to growth incorporating several pulses of carbon-nitrogen fluid with distinct isotopic compositions. Most of these growth events show decoupled carbon and nitrogen systematics. In addition, EBSD identifies deformation and recrystallization and nitrogen aggregation states range from pure IaA to pure IaB, supporting a heterogeneous and episodic growth history.
DS201909-2076
2019
Piazzi, M.Piazzi, M., Morana, M., Coisson, M., Marone, F., Campione, M., Bindi, L., Jones, A.P., Ferrara, E., Alvaro, M.Multi-analytical characterization of Fe-rich magnetic inclusions in diamonds.Diamonds and Related Materials, in press available 36p. PdfAfrica, Ghanadeposit - Akwatia

Abstract: Magnetic mineral inclusions, as iron oxides or sulfides, occur quite rarely in natural diamonds. Nonetheless, they represent a key tool not only to unveil the conditions of formation of host diamonds, but also to get hints about the paleointensity of the geomagnetic field present at times of the Earth's history otherwise not accessible. This possibility is related to their capability to carry a remanent magnetization dependent on their magnetic history. However, comprehensive experimental studies on magnetic inclusions in diamonds have been rarely reported so far. Here we exploit X-ray diffraction, Synchrotron-based X-ray Tomographic Microscopy and Alternating Field Magnetometry to determine the crystallographic, morphological and magnetic properties of ferrimagnetic Fe-oxides entrapped in diamonds coming from Akwatia (Ghana). We exploit the methodology to estimate the natural remanence of the inclusions, associated to the Earth's magnetic field they experienced, and to get insights on the relative time of formation between host and inclusion systems. Furthermore, from the hysteresis loops and First Order Reversal Curves we determine qualitatively the anisotropy, size and domain state configuration of the magnetic grains constituting the inclusions.
DS201910-2292
2019
Piazzi, M.Piazzi, M., Morana, M., Coisson, M., Marone, F., Campione, M., Bindi, L., Jones, A.P., Ferrara, E., Alvaro, M.Multi-analytical characterization of Fe-rich magnetic inclusions in diamonds. Akwatiaresearchgate.net, June 18, 333866141 12p. PdfAfrica, Ghanadeposit - Akwatia

Abstract: Magnetic mineral inclusions, as iron oxides or sulfides, occur quite rarely in natural diamonds. Nonetheless, they represent a key tool not only to unveil the conditions of formation of host diamonds, but also to get hints about the paleointensity of the geomagnetic field present at times of the Earth's history otherwise not accessible. This possibility is related to their capability to carry a remanent magnetization dependent on their magnetic history. However, comprehensive experimental studies on magnetic inclusions in diamonds have been rarely reported so far. Here we exploit X-ray diffraction, Synchrotron-based X-ray Tomographic Microscopy and Alternating Field Magnetometry to determine the crystallographic, morphological and magnetic properties of ferrimagnetic Fe-oxides entrapped in diamonds coming from Akwatia (Ghana). We exploit the methodology to estimate the natural remanence of the inclusions, associated to the Earth's magnetic field they experienced, and to get insights on the relative time of formation between host and inclusion systems. Furthermore, from the hysteresis loops and First Order Reversal Curves we determine qualitatively the anisotropy, size and domain state configuration of the magnetic grains constituting the inclusions.
DS200812-0896
2007
Piazzoni, A.S.Piazzoni, A.S., Steinle-Neumann, G., Bunge, H-P., Dolejs, D.A mineralogical model for density and elasticity of the Earth's mantle.Geochemistry, Geophysics, Geosystems: G3, Vol. 8, 11, Nov. 30, pp. 1-23.MantleMineralogy
DS1983-0522
1983
Piboule, M.Pouclet, A., Menot, R.P., Piboule, M.Le magmatism Alaclin Potassique de L'aire Volcanique des ViBulletin. MINERALOGIQUE., Vol. 106, PP. 607-622.East AfricaRift, Melilite, Leucite, Related Rocks
DS1987-0367
1987
Piboule, M.Kornprobst, J., Piboule, M., Tabit, A.Variety of garnet pyroxenites related to orogenic ultramafic bodies-eclogites, ariegites, griquaites or grospydites- a discussion.(in French)Bulletin Societe Geologique France, (in French), Vol. 3, No. 2, pp. 345-351GlobalPetrology
DS1989-0098
1989
Piboule, M.Begou, P., Amosse, J., Fischer, W., Piboule, M.platinum group elements (PGE) distribution into the Lherz massive spinel peridotite (Ariege) France. Preliminary results.(in French)Comptes Rendus, (in French), Vol. 309, No. 11, October 12, pp.1177-1182FrancePlatinuM., Lherzolite
DS1990-0876
1990
Piboule, M.Kornprobst, J., Piboule, M., Roden, M., Tabit, A.Corundum bearing garnet clinopyroxenites at Beni Bousera (Morocco):original plagioclase rich gabbros recrystallized at depth within the mantle?Journal of Petrology, Vol. 31, pt. 3, pp. 717-745MoroccoMantle, Gabbros
DS1990-0877
1990
Piboule, M.Kornprobst, J., Piboule, M., Roden, M., Tabit, A.Corundum-bearing garnet clinopyroxenites at Beni-Bousera (Morocco)-original plagioclase-rich gabbros recrystallized at depth within the mantleJournal of Petrology, Vol. 31. No. 3, June pp. 597-628MoroccoPetrology, Beni-Bousera
DS1990-1180
1990
Piboule, M.Picard, C., Lamothe, D., Piboule, M., Oliver, R.Magmatic and geotectonic evolution of a Proterozoic oceanic basin system:the Cape Smith Thrust- Fold Belt.Precambrian Research, Vol. 47, pp. 223-249.Quebec, Labrador, New QuebecTectonics, Structure
DS1998-1162
1998
Piboule, M.Piboule, M., Gueddari, K.Petrology and geochemistry of some unusual corundum bearing garnet pyroxenites Ronda lherzolitic MassifMineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 1172-3.GlobalPetrography, geochemistry, CorunduM.
DS1992-0512
1992
PicardGaonach, H., Ludden, Picard, FrancisHighly alkaline lavas in a Proterozoic rift zone: implications for Precambrian mantle metasomatic processGeology, Vol. 20, Mar. pp. 247-50.Labrador, Ungava, QuebecTectonics, Cape Smith thrust belt, Mantle metasomatism, Alkaline lavas, Nephelinites, basanites
DS1989-0468
1989
Picard, C.Gaonach, H., Picard, C., Ludden, J.N., Francis, D.M.Alkaline rocks from a Proterozoic volcanic island in the Cape Smith thrustbelt, New Quebec.Geoscience Canada, Vol. 16, No. 3, September pp. 137-139QuebecBasanite, Nephelinite, phonolites, Proterozoic
DS1989-0469
1989
Picard, C.Gaonac'h, H., Picard, C., Ludden, J.N., Francis, D.M.Alkaline rocks from a Proterozoic volcanic island In the Cape Smith thrust belt, New QuebecGeoscience Canada, Vol. 16, No. 3, pp. 137-9.Quebec, Ungava, LabradorAlkaline rocks
DS1989-1212
1989
Picard, C.Picard, C., Publoule, M.The Ungava trough Proterozoic basalts, Quebec- a very well preserved example of abyssal lava. (in French)Bulletin. de la Soc. Geologique de France, (in French), Vol. 5, No. 4, July-August pp. 723-736Quebec, Labrador, UngavaProterozoic basalts
DS1990-1180
1990
Picard, C.Picard, C., Lamothe, D., Piboule, M., Oliver, R.Magmatic and geotectonic evolution of a Proterozoic oceanic basin system:the Cape Smith Thrust- Fold Belt.Precambrian Research, Vol. 47, pp. 223-249.Quebec, Labrador, New QuebecTectonics, Structure
DS2002-1356
2002
Picard, C.Rolland, Y., Picard, C., Pecher, Lapierre, Bosch, KellerThe Cretaceous Ladakh arc of NW Himalaya slab melting and melt mantle interaction during fast northward driftChemical Geology, Vol.182, 2-4, Feb.15, pp.139-78.India, northwest HimalayasMelting, slab subduction, Indian Plate
DS201805-0941
2018
Picazo, S.Chenin, P., Picazo, S., Jammes, S., Manatschal, G., Muntener, O., Karner, G.Potential role of lithospheric mantle composition in the Wilson cycle: a North American perspective.Geological Society of London, Special Publication, Vol. 470, doi:10.1144 /SP470.10Mantlewilson cycle

Abstract: Although the Wilson cycle is usually considered in terms of wide oceans floored with normal oceanic crust, numerous orogens result from the closure of embryonic oceans. We discuss how orogenic and post-orogenic processes may be controlled by the size/maturity of the inverted basin. We focus on the role of lithospheric mantle in controlling deformation and the magmatic budget. We describe the physical properties (composition, density, rheology) of three types of mantle: inherited, fertilized and depleted oceanic mantle. By comparing these, we highlight that fertilized mantle underlying embryonic oceans is mechanically weaker, less dense and more fertile than other types of mantle. We suggest that orogens resulting from the closure of a narrow, immature extensional system are essentially controlled by mechanical processes without significant thermal and lithological modification. The underlying mantle is fertile and thus has a high potential for magma generation during subsequent tectonic events. Conversely, the thermal state and lithology of orogens resulting from the closure of a wide, mature ocean are largely modified by subduction-related arc magmatism. The underlying mantle wedge is depleted, which may inhibit magma generation during post-orogenic extension. These end-member considerations are supported by observations derived from the Western Europe-North Atlantic region.
DS1993-1650
1993
Piccado, G.B.Vannucci, R., Shimizu, N., Piccado, G.B., Ottolini, L., Bottazzi, P.Distribution of trace elements during breakdown of mantle garnet: an example from Zabargad.Contribution to Mineralogy and Petrology, Vol. 113, pp. 437-449.GlobalMantle, Garnet geochronology
DS1995-1662
1995
Piccardo, et al.Scambelluri, M., Muntener, O., Hermann, J., Piccardo, et al.Subduction of water into mantle: history of an Alpine peridotiteGeology, Vol. 23, No. 5, May pp. 459-462.GlobalSubduction, Peridotite
DS1975-0380
1976
Piccardo, G.B.Piccardo, G.B.Petrology of the Lherzolite Massif of Cape Suvero, la SpeziaOfioliti, Vol. 1, No. 2, PP. 279-317.ItalyBlank
DS2001-0919
2001
Piccardo, G.B.Piccardo, G.B., Rampone, E.Strongly depleted Mid Ocean Ridge Basalt (MORB) melts at extensional settings: peculiar mafic ultramafic intrusive suiteMt. MaggioreGeological Association of Canada (GAC) Annual Meeting Abstracts, Vol. 26, p. 118.abstract.France, CorsicaPeridotite
DS2001-1291
2001
Piccardo, G.B.Zanetti, A., Vanucci, R., Piccardo, G.B.The lithospheric mantle beneath the Assab region: a LAM ICP Ms study of peridotite and pyroxenite xenoliths.Plinius, No. 24, pp. 223-4. abstractGlobalXenoliths, Afur region - eastern African Rift
DS200712-0718
2007
Piccardo, G.B.Mentener, O., Piccardo, G.B.Melt rock reaction processes in the mantle and their bearing on mantle petrology and chemistry.Lithos, Vol. 99, 1-2, pp. 3p. introduction.MantleMelting
DS200712-0869
2007
Piccardo, G.B.Ranalli, G., Piccardo, G.B., Corona Chavez, P.Softening of the continental lithsopheric mantle by asthenospheric melts and the continental extension /oceanic spreading transition.Journal of Geodynamics, Vol. 43, 4-5, pp. 450-464.MantleMelting
DS200712-0235
2007
Piccinini, M.Della Ventura, G., Bellatreccia, F., Piccinini, M.Water in leucite, a nominally anhydrous volcanic mineral.Frontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p. 269.Europe, ItalyWater storage
DS200712-0236
2007
Piccinini, M.Della Ventura, G., Bellatreccia, F., Piccinini, M.Water in leucite, a nominally anhydrous volcanic mineral.Frontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p. 269.Europe, ItalyWater storage
DS2000-0780
2000
PiccirilloPrincivalle, F., Salviulo, G., Marzoli, PiccirilloClinopyroxene of spinel peridotite mantle xenoliths from Lake Nji: crystal chemistry and petrological....Contributions to Mineralogy and Petrology, Vol. 139, No. 5, pp. 503-8.GlobalMantle xenoliths
DS2003-1368
2003
PiccirilloTeixeira, W., Pinese, J.P.P., Iacumin, V.V., Girardi, Piccirillo, Echevests, RibotCalc alkaline and tholeiitic dyke swarms of Tandilia, Rio de la Plat a Craton, Argentina:Precambrian Research, Vol. 119, 1-4, Dec. 20, pp. 329-353.ArgentinaTrans Amazonian Orogeny
DS1986-0160
1986
Piccirillo, E.M.Cundari, J.B., Dal Negro, A., Piccirillo, E.M., Della Gusta, A., SeccoIntracrystalline relationships in olivine, orthopyroxene, clinopyroxeneContributions to Mineralogy and Petrology, Vol. 94, No. 4, pp. 523-532AustraliaXenoliths, Mineralogy
DS1987-0132
1987
Piccirillo, E.M.Dal Negro, A., Cundari, A., Piccirillo, E.M., Salviulo, G.Genetic significance of the clinopyroxene from lamproites and relatedrocks: a crystal chemical studyTerra Cognita, Conference abstracts Oceanic and Continental Lithosphere:, Vol. 7, No. 4, Autumn, abstract only p. 610AustraliaBlank
DS1990-1181
1990
Piccirillo, E.M.Piccirillo, E.M., Bellieni, G., Cavazzini, G., Comin-Chiaramonti, P.Lower Cretaceous tholeiitic dyke swarms from the Ponta Grossa ArchChemical Geology, Vol. 89, pp. 19-48BrazilBasaltic dykes, Mantle-peridotite
DS1991-0283
1991
Piccirillo, E.M.Comin-Chiaramonti, P., Civetta, L., Petrini, R., Piccirillo, E.M.Tertiary nephelinitic magmatism in eastern Paraguay: petrologyEuropean Journal of Mineralogy, Vol. 3, No. 2, pp. 507-525GlobalNephelinite, ankaramite -Asuncion, Mantle nodules, geochemistry
DS1992-0113
1992
Piccirillo, E.M.Bellieni, G., Macedo, M.H.F., Petrini, R., Piccirillo, E.M.Evidence of magmatic activity related to Middle Jurassic and LowerChemical Geology, Vol. 97, No. 1/2, May 15, pp. 9-32BrazilTectonics, Geochronology
DS1994-1108
1994
Piccirillo, E.M.Marques, L.S., Piccirillo, E.M.What was the role of Tristan da Cunha mantle plume in the Parana flood basalt generation?International Symposium Upper Mantle, Aug. 14-19, 1994, Extended abstracts pp. 49-51.BrazilMagma, Mantle plume
DS1995-0136
1995
Piccirillo, E.M.Bellieni, G., Piccirillo, E.M., et al.Petrological and Strontium neodymium evidence bearing on early Proterozoic magmatic events of subcontinental mantleContributions to Mineralogy and Petrology, Vol. 122, No. 3, Dec. pp. 252-261.BrazilCraton -Sao Francisco, Geochronology
DS1995-0137
1995
Piccirillo, E.M.Bellieni, G., Piccirillo, E.M., Tanner de Oliviera, M.A.Petrological and Sr-neodymium evidence bearing on Early Proterozoic magmatic events of the sub-cont. mantle..Contributions to Mineralogy and Petrology, Vol. 122, No. 3, pp. 252-261BrazilGeochronology, Craton -Sao Francisco
DS1999-0015
1999
Piccirillo, E.M.Antonini, P., Piccirillo, E.M.Enriched mantle - Dupal signature in the genesis of the Jurassic Ferrartholeiites from Prince Albert MountainsContributions to Mineralogy and Petrology, Vol. 136, No. 1-2, pp. 1-19.GlobalGeology - enriched mantle - not specific to diamonds
DS2003-0615
2003
Piccirillo, E.M.Iacumin, M., DeMin, A., Piccirillo, E.M., Bellieni, G.Source mantle heterogeneity and its role in the genesis of Late Archean Proterozoic (Earth Science Reviews, Vol. 62, 3-4, pp. 365-397.South AmericaMagmatism
DS200412-0864
2003
Piccirillo, E.M.Iacumin, M., DeMin, A., Piccirillo, E.M., Bellieni, G.Source mantle heterogeneity and its role in the genesis of Late Archean Proterozoic ( 2.7 - 1.0 Ga) and Mesozoic (200 and 130 MaEarth Science Reviews, Vol. 62, 3-4, pp. 365-397.South AmericaMagmatism
DS201904-0718
1991
Piccirillo, E.M.Bossi, J., Campal, N., Civetta, L., Demarchi, G., Girardi, V.V., Mazzucchelli, M., Piccirillo, E.M., Rivalenti, G., Sinigol, S., Teixeira, W., Fragoso-Cesar, A.R.Petrological and geochronological aspects of the Precambrian mafic dyke swarm of Uruguay. IN: Eng. Note Date****BOL.IG-USP, Publ.Esp., Vol. 10, pp. 35-42.South America, Uruguaydykes

Abstract: The subparallel maflc dykes of the Aorida-Durazno-S.José region (SW Uruguay) trend N60-80W and vary in thickness from 0.6 to 50 m. They are part of the mafic dyke swarms intrudlng granitic-gnelssic basement that were mappecl by BOSSI et ai. (1989), In an ares approximately 200 km In length and 100 km in bresdth. Plagioclass, augite, subcalclc augite (plgeonite) and opaques are the maln components of the dykes. Orthopyroxene and oIlvine are very rare. Blotite and homblende are secondary minerais. Quartz-feldspar Intergrowths occur In the coarser gralnecl dykes. The characterlstlc textures are subophitic and intersertal.
DS200712-1107
2007
PiccoliVan Acken, D., Becker, H., Wombacher, Walker, McDonough, Ash, PiccoliFractionated HSE in suboceanic mantle: assessing the influence of refertilization processes on upper mantle peridotites.Plates, Plumes, and Paradigms, 1p. abstract p. A1051.Europe, SwitzerlandWebsterite
DS1989-0928
1989
Piccoli, P.M.Maniar, P.D., Piccoli, P.M.Tectonic discrimination of granitoidsGeological Society of America (GSA) Bulletin, Vol. 101, No. 5, May pp. 635-643GlobalGranite, Tectonics
DS201112-0611
2011
Piccoli, P.M.Liu, J., Rudnick, R.L., Walker, R.J., Gao, S., Wu, F-y., Piccoli, P.M., Yuan, H., Xu, W-l., Xu, Yi-G.Mapping lithospheric boundaries using Os isotopes of mantle xenoliths: an example from the North Chin a Craton.Geochimica et Cosmochimica Acta, Vol. 75, 13, pp. 3881-3902.ChinaGeochronology
DS201904-0761
2019
Piccoli, P.M.Nicklas, R.W., Puchtel, I.S., Ash, R.D., Piccoli, P.M., Hanski, M., Eero, Nisbet, E.G., Waterton, P., Pearson, D.G., Anbar, A.D.Secular mantle oxidation across the Archean - Proterozoic boundary: evidence from V partitioning in komatiites and picrites.Geochimica et Cosmochimica Acta, Vol. 250, 1, pp. 49-75.Mantlepicrites

Abstract: The oxygen fugacities of nine mantle-derived komatiitic and picritic systems ranging in age from 3.55?Ga to modern day were determined using the redox-sensitive partitioning of V between liquidus olivine and komatiitic/picritic melt. The combined set of the oxygen fugacity data for seven systems from this study and the six komatiite systems studied by Nicklas et al. (2018), all of which likely represent large regions of the mantle, defines a well-constrained trend indicating an increase in oxygen fugacity of the lavas of ?1.3 ?FMQ log units from 3.48 to 1.87?Ga, and a nearly constant oxygen fugacity from 1.87?Ga to the present. The oxygen fugacity data for the 3.55?Ga Schapenburg komatiite system, the mantle source region of which was previously argued to have been isolated from mantle convection within the first 30?Ma of the Solar System history, plot well above the trend and were not included in the regression. These komatiite’s anomalously high oxygen fugacity data likely reflect preservation of early-formed magma ocean redox heterogeneities until at least the Paleoarchean. The observed increase in the oxygen fugacity of the studied komatiite and picrite systems of ?1.3 ?FMQ log units is shown to be a feature of their mantle source regions and is interpreted to indicate secular oxidation of the mantle between 3.48 and 1.87?Ga. Three mechanisms are considered to account for the observed change in the redox state of the mantle: (1) recycling of altered oceanic crust, (2) venting of oxygen from the core due to inner core crystallization, and (3) convection-driven homogenization of an initially redox-heterogeneous primordial mantle. It is demonstrated that none of the three mechanisms alone can fully explain the observed trend, although mechanism (3) is best supported by the available geochemical data. These new data provide further evidence for mantle involvement in the dramatic increase in the oxygen concentration of the atmosphere leading up to the Great Oxidation Event at ?2.4?Ga.
DS202011-2028
2020
Piccoli, P.M.Apen, F.E., Rudnick, R.L., Cottle, J.M., Kylander-Clark, A.R.C., Blondes, M.S., Piccoli, P.M., Seward, G.Four dimensional thermal evolution of the East African Orogen: accessory phase petrochronology of crustal profiles through the Tanzanian Craton and Mozambique belt, northeastern Tanzania.Contributions to Mineralogy and Petrology, Vol. 175, 97, 30p. PdfAfrica, Tanzaniacraton

Abstract: U-Pb petrochronology of deep crustal xenoliths and outcrops across northeastern Tanzania track the thermal evolution of the Mozambique Belt and Tanzanian Craton following the Neoproterozoic East African Orogeny (EAO) and subsequent Neogene rifting. At the craton margin, the upper-middle crust record thermal quiescence since the Archean (2.8-2.5 Ga zircon, rutile, and apatite in granite and amphibolite xenoliths). The lower crust of the craton documents thermal pulses associated with Neoarchean ultra-high temperature metamorphism (ca. 2.64 Ga,?>?900 °C zircon), the EAO (600-500 Ma rutile), and fluid influx during rifting (?650 °C (above Pb closure of rutile and apatite) at the time of eruption. Zoned titanite records growth during cooling of the lower crust at 550 Ma, followed by fluid influx during slow cooling and exhumation (0.1-1 °C/Myr after 450 Ma). Permissible lower-crustal temperatures for the craton and orogen suggest variable mantle heat flow through the crust and reflect differences in mantle lithosphere thickness rather than advective heating from rifting.
DS202102-0186
2021
Piccoli, P.M.Feng, P., Wang, L., Brown, M., Johnson, T.E., Kylander-Clark, A., Piccoli, P.M.Partial melting of ultrahigh pressure eclogite by omphacite-breakdown facilitates exhumation of deeply-subducted crust.Earth and Planetary Science Letters, Vol. 554, doi.org/10.1016/ j.epsl.2020. 116664 13p. PdfMantleeclogite

Abstract: Results from numerical modelling and experimental petrology have led to the hypothesis that partial melting was important in facilitating exhumation of ultrahigh-pressure (UHP) metamorphic rocks from mantle depths. However, the melting reactions responsible are rarely well-documented from natural examples. Here we report microstructural features and compositional data that indicate in situ partial melting dominated by breakdown of omphacite in UHP eclogite from the Sulu belt, China. Diagnostic microstructures include: (i) the presence of in situ leucosome pockets composed of plagioclase, euhedral amphibole, minor K-feldspar and epidote within host zoisite- and phengite-bearing eclogite; (ii) skeletal omphacite within the leucosome pockets that has a lower jadeite content (25-45 mol.%) than rock-forming omphacite (39-54 mol.%); and, (iii) seams of Na-rich plagioclase that extend along grain boundaries separating phengite, quartz and zoisite, and which commonly exhibit low dihedral angles where they terminate at triple grain-boundary junctions. Major oxide proportions of 57 leucosome pockets, calculated using mineral modes and compositions, yield leucodiorite bulk compositions characterized by intermediate SiO2, high Al2O3 and Na2O, and low K2O contents. In primitive mantle-normalised trace element diagrams, the leucosome pockets show enrichment in large ion lithophile elements, U, Pb, Zr, Hf and Ti, but depletion in Th and Ta, patterns that are similar to those of rock-forming omphacite. Rather than forming predominantly by breakdown of phengite and/or zoisite, as widely proposed in the literature, the leucosome pockets have petrographic characteristics and major oxide and trace element compositions that are consistent with partial melting dominated by omphacite breakdown. Based on conventional thermobarometry, the eclogite was exhumed from pressure-temperature (P-T) conditions of 3.6-3.1 GPa and 900-840 °C. Partial melting led to the formation of the leucosome pockets, which equilibrated with the rims of surrounding rock-forming garnet and pyroxene during crystallisation. Conventional thermobarometry using rim compositions yields P-T conditions of 1.6-1.2 GPa and 780-690 °C, broadly consistent with calculated phase equilibria and Ti-in-zircon temperatures from zircon overgrowths. Weighted mean ages of ca 217-214 Ma from thin overgrowths on zircon are interpreted to record melt crystallisation. This study provides insight into an overlooked mechanism by which eclogites partially melt during exhumation from UHP conditions, and permits a better understanding of the processes that assist deeply-subducted continental crust to return to shallower depths.
DS201906-1335
2019
Piccolo, A.Piccolo, A., Palin, R.M., Kaus, B.J.P., White, R.W.Generation of Earth's early continents from a relatively cool Archean mantle.Geochemistry, Geophysics, Geosystems, Vol. 20, 4, pp. 1679-1697.Mantleplate tectonics

Abstract: It has been believed that early Earth featured higher mantle temperature. The mantle temperature affects the geodynamic processes, and, therefore, the production of the continental crust, which has been a stable environment for the developing of life since Earth's infancy. However, our knowledge of the processes operating during the early Earth is still not definitive. The wide range of the mantle temperature estimation (from 1500 to 1600 °C) hampered our ability to understand early Earth's dynamic and geological data alone cannot provide a definitive answer. Therefore, it is necessary to integrate them with numerical modeling. Our contribution conjugates petrological modeling with thermal?mechanical simulations to unveil the effect of continental crust production. Continental crust's extraction from partially melted hydrated basalts leaves behind dense rocks that sink into the mantle dragging part of surface hydrated rocks. These drips produce a major compositional change of the mantle and promote the production of new basaltic/continental crust. The combination of these processes cools the mantle, suggesting that it could not have been extremely hot for geological timescales. We show that such processes can be active even in a relatively cool mantle (1450-1500 °C), providing new constraints to understand the infancy of our planet.
DS202103-0399
2021
Piccolo, A.Piccolo, A., Kaus, B.J.P., White, R.W., Palin, R.M., Reuber, G.S.Plume - Lid interactions during the Archean and implications for the generation of early continental terranes.Gondwana Research, Vol. 88, pp. 150-168. 19p. PdfMantlegeodynamics

Abstract: Many Archean terranes are interpreted to have a tectonic and metamorphic evolution that indicates intra-crustal reorganization driven by lithospheric-scale gravitational instabilities. These processes are associated with the production of a significant amount of felsic and mafic crust, and are widely regarded to be a consequence of plume-lithosphere interactions. The juvenile Archean felsic crust is made predominantly of rocks of the tonalite-trondhjemite-granodiorite (TTG) suite, which are the result of partial melting of hydrous metabasalts. The geodynamic processes that have assisted the production of juvenile felsic crust, are still not well understood. Here, we perform 2D and 3D numerical simulations coupled with the state-of-the-art of petrological thermodynamical modelling to study the tectonic evolution of a primitive Archean oceanic plateau with particular regard on the condition of extraction of felsic melts. In our numerical simulations, the continuous emplacement of new, dry mafic intrusions and the extraction of the felsic melts, generate an unstable lower crust which drips into the mantle soon after the plume arrival. The subsequent tectonic evolution depends on the asthenosphere TP. If the TP is high enough (? 1500 ?C) the entire oceanic crust is recycled within 2 Myrs. By contrast at low TP, the thin oceanic plateau slowly propagates generating plate-boundary like features.
DS200712-0912
2007
Piccrillo, E.M.Rosset, A., De Min, A., Marques, L.S., Macambira, M.J.B., Ernesto, M., Renne, P.R., Piccrillo, E.M.Genesis and geodynamic significance of Mesoproterozoic and Early Cretaceous tholeiitic dyke swarms from the Sao Francisco Craton, Brazil.Journal of South American Earth Sciences, Vol. 24, 1, June pp. 69-92.South America, BrazilDyke swarms
DS1930-0118
1932
Pichamuthu, C.S.Pichamuthu, C.S., Rao, R.M.B.A Note on the Tuff of WajrakarurIndian Sci. Congr. 19th. Session Proceedings, ABSTRACT.India, Andhra PradeshPetrography
DS1975-0381
1976
Pichamuthu, C.S.Pichamuthu, C.S.Group Discussion on the Carbonatite Kimberlite Complexes Ofindia.Geological Society INDIA Journal, Vol. 17, No. 4, PP. 566-568.IndiaBlank
DS201012-0592
2010
Pichavant, M.Pommier, A., Gaillard, F., Pichavant, M.Time dependent changes of the electrical conductivity of basaltic melts with redox state.Geochimica et Cosmochimica Acta, Vol. 74, 5, pp. 1653-1671.MantleRedox
DS201605-0895
2016
Pichavant, M.Scaillet, B., Holtz, F., Pichavant, M.Enigmatic relationship between silicic volcanic and plutonic rocks: experimental constraints on the formation of silicic magmas.Elements, Vol. 12, pp. 109-114.TechnologyMagmatism
DS1996-1484
1996
Pichugin, L.P.Vinogradov, V.I., Pichugin, L.P., Buyakaite, M.I.Isotopic features and dating of epigenetic alterations of upper Precambrian deposits of the Ural UpliftLithology and Mineral resources, Vol. 31, No. 1, Jan. pp. 60-69Russia, UralsAlteration, Geochronology
DS1996-0084
1996
Pickard, A.L.Barley, M.E., Pickard, A.L., Sylvester, P.J.Emplacement of a large igneous province as a possible cause of banded iron formation 2.45 billion years agoNature, Vol. 385, No. 6611, Jan. 2, pp. 55-59GlobalBIF., Iron Formation, deposition, magmatism, metasomatism
DS2000-0058
2000
Pickard, A.L.Barley, M.E., Krapez, B., Pickard, A.L.Late Archean 2.72 to 2.83 and early paleoproterozoic 2.47 to 2.45 Ga breakout events.Geological Society of America (GSA) Abstracts, Vol. 32, No. 7, p.A-315.AustraliaGeochronology - Proterozoic not specific to diamonds
DS201607-1311
2016
Pickels, J.R.Pickels, J.R., Blundy, J.D., Brroker, R.A.Trace element thermometry of garnet-clinopyroxene pairs. ( diamond formation)American Mineralogist, Vol. 101, pp. 1438-1450.MantleGeothermometry

Abstract: We present major and trace element data on coexisting garnet and clinopyroxene from experiments carried out between 1.3 and 10 GPa and 970 and 1400 °C. We demonstrate that the lattice strain model, which was developed for applications to mineral-melt partitioning, can be adapted to garnet-clinopyroxene partitioning. Using new and published experimental data we develop a geothermometer for coexisting garnet and clinopyroxene using the concentration of rare earth elements (REE). The thermometer, which is based on an extension of the lattice strain model, exploits the tendency of minerals at elevated temperatures to be less discriminating against cations that are too large or too small for lattice sites. The extent of discrimination against misfit cations is also related to the apparent elasticity of the lattice site on which substitution occurs, in this case the greater stiffness of the dodecahedral X-site in garnet compared with the eightfold M2-site in clinopyroxene. We demonstrate that the ratio of REE in clinopyroxene to that in coexisting garnet is particularly sensitive to temperature. We present a method whereby knowledge of the major and REE chemistry of garnet and clinopyroxene can be used to solve for the equilibrium temperature. The method is applicable to any scenario in which the two minerals are in equilibrium, both above and below the solidus, and where the mole fraction of grossular in garnet is less than 0.4. Our method, which can be widely applied to both peridotitic and eclogitic paragenesis with particular potential for diamond exploration studies, has the advantage over commonly used Fe-Mg exchange thermometers in having a higher closure temperature because of slow interdiffusion of REE. The uncertainty in the calculated temperatures, based on the experimental data set, is less than ±80 °C.
DS1990-1447
1990
Pickering, K.T.Tarney, J., Pickering, K.T., Knipe, R.J., Dewey, J.F.The behaviour and influence of fluids in subduction zonesPhil. Transactions Royal Soc. London, Vol. 335, pp. 225-418GlobalMagmas, Subduction zones
DS2003-1296
2003
Pickering, K.T.Smith, A.G., Pickering, K.T.Oceanic gateways as a critical factor to initiate icehouse EarthJournal of the Geological Society of London, Vol. 160, 3, pp. 337-340.OceanBlank
DS200412-1856
2003
Pickering, K.T.Smith, A.G., Pickering, K.T.Oceanic gateways as a critical factor to initiate icehouse Earth.Journal of the Geological Society, Vol. 160, 3, pp. 337-340.OceanGeomorphology
DS1910-0038
1910
Pickering, W.H.Crookes, W., Pickering, W.H.Diamonds in Comet, Say ScientistsPittsburg Gazette Times, JUNE 5TH.GlobalDiamond Genesis, Meteorite
DS2002-1257
2002
Pickering Jr., S.M.Pickering Jr., S.M.Helping banks to manage mineral land trustsSme Preprint, No. 02-120, 2p.United StatesLegal - brief overview
DS2003-0799
2003
Pickering Witter, J.Lesher, C.E, Pickering Witter, J., Baxterm G., Walter, M.Melting of garnet peridotite: effects of capsules and thermocouples, and implications forAmerican Mineralogist, Vol. 88, 8-9, pp. 1181-89.MantleGeothermometry, UHP
DS200412-1119
2003
Pickering Witter, J.Lesher, C.E, Pickering Witter, J., Baxter, G., Walter, M.Melting of garnet peridotite: effects of capsules and thermocouples, and implications for the high pressure mantle solidus.American Mineralogist, Vol. 88, 8-9, pp. 1181-89.MantleGeothermometry, UHP
DS2001-0920
2001
Pickering-Witter, J.Pickering-Witter, J., Johnston, A.D.The effects of variable bulk composition on the melting systematics of fertile peridotitic assemblages.Contributions to Mineralogy and Petrology, Vol. 140, No. 2, pp. 190-211.GlobalMineral chemistry, Peridotites
DS200512-0753
2005
Pickett, C.Mueller, W.U., Corcoran, P.L., Pickett, C.Mesoarchean continental breakup: evolution and inferences from the >2.8 Ga Slave Craton - cover succession, Canada.Journal of Geology, Vol. 113, 1, pp. 23-46.Canada, Northwest TerritoriesTectonics
DS200912-0231
2008
Pickles, J.Frost, D.J., Asahara, Y., Tsuno, K., Rubie, D.C., Pickles, J.An experiment based model describing the partitioning of oxygen between Earth's mantle and core.American Geological Union, Fall meeting Dec. 15-19, Eos Trans. Vol. 89, no. 53, meeting supplement, 1p. abstractMantleUHP
DS201112-0795
2011
Pickles, J.Pickles, J., Blundy, J.D., Sweeney, R., Smith, C.B.Experimental investigation of garnet cpx geobarometers in eclogites.Goldschmidt Conference 2011, abstract p.1640.TechnologyGeothermometry
DS202003-0332
2020
Pickles, J.P.Broom-Fendley, S., Smith, M.P., Andrade, M.B., Ray, S., Banks, D.A., Loye, E., Antencio, D., Pickles, J.P., Wall, F.Sulfur bearing monzazite (Ce) from the Eureka carbonatite, Namibia: oxidation state, substitution mechanism, and formation conditions.Mineralogical Magazine, pp. 1-14, pdfAfrica, Namibiacarbonatite, REE

Abstract: Sulfur-bearing monazite-(Ce) occurs in silicified carbonatite at Eureka, Namibia, forming rims up to ~0.5 mm thick on earlier-formed monazite-(Ce) megacrysts. We present X-ray photoelectron spectroscopy data demonstrating that sulfur is accommodated predominantly in monazite-(Ce) as sulfate, via a clino-anhydrite-type coupled substitution mechanism. Minor sulfide and sulfite peaks in the X-ray photoelectron spectra, however, also indicate that more complex substitution mechanisms incorporating S2 and S4+ are possible. Incorporation of S6+ through clino-anhydrite-type substitution results in an excess of M2+ cations, which previous workers have suggested is accommodated by auxiliary substitution of OH for O2. However, Raman data show no indication of OH, and instead we suggest charge imbalance is accommodated through F substituting for O2. The accommodation of S in the monazite-(Ce) results in considerable structural distortion that may account for relatively high contents of ions with radii beyond those normally found in monazite-(Ce), such as the heavy rare earth elements, Mo, Zr and V. In contrast to S-bearing monazite-(Ce) in other carbonatites, S-bearing monazite-(Ce) at Eureka formed via a dissolutionprecipitation mechanism during prolonged weathering, with S derived from an aeolian source. While large S-bearing monazite-(Ce) grains are likely to be rare in the geological record, formation of secondary S-bearing monazite-(Ce) in these conditions may be a feasible mineral for dating palaeo-weathering horizons.
DS201906-1278
2019
Pickles, J.R.Broom-Fendley, S., Smith, M., Andrade, M.B., Ray, S., Banks, D.A., Loye, E., Atencio, D., Pickles, J.R., Wall, F.Sulphate bearing monazite (Ce) from silicified dolomite carbonatite, Eureka, Namibia: substitution mechanisms, redox state and HREE enrichment.3rd International Critical Metals Meeting held Edinburgh, 1p. Abstract p. 51.Africa, Namibiadeposit - Eureka
DS202106-0925
2021
Pickles, J.R.Broom-Findley, S., Siegfried, P.R., Wall, F., O'Neill, M., Brooker, R.A., Fallon, E.K., Pickles, J.R., Banks, D.A.The origin and composition of carbonatite-derived carbonate bearing fluorapatite deposits.Mineralium Deposita, Vol. 56, pp. 863-884.Globaldeposit - Kovdor, Sokli, Bukusu, Catalao 1, Glenover

Abstract: Carbonate-bearing fluorapatite rocks occur at over 30 globally distributed carbonatite complexes and represent a substantial potential supply of phosphorus for the fertiliser industry. However, the process(es) involved in forming carbonate-bearing fluorapatite at some carbonatites remain equivocal, with both hydrothermal and weathering mechanisms inferred. In this contribution, we compare the paragenesis and trace element contents of carbonate-bearing fluorapatite rocks from the Kovdor, Sokli, Bukusu, Catalão I and Glenover carbonatites in order to further understand their origin, as well as to comment upon the concentration of elements that may be deleterious to fertiliser production. The paragenesis of apatite from each deposit is broadly equivalent, comprising residual magmatic grains overgrown by several different stages of carbonate-bearing fluorapatite. The first forms epitactic overgrowths on residual magmatic grains, followed by the formation of massive apatite which, in turn, is cross-cut by late euhedral and colloform apatite generations. Compositionally, the paragenetic sequence corresponds to a substantial decrease in the concentration of rare earth elements (REE), Sr, Na and Th, with an increase in U and Cd. The carbonate-bearing fluorapatite exhibits a negative Ce anomaly, attributed to oxic conditions in a surficial environment and, in combination with the textural and compositional commonality, supports a weathering origin for these rocks. Carbonate-bearing fluorapatite has Th contents which are several orders of magnitude lower than magmatic apatite grains, potentially making such apatite a more environmentally attractive feedstock for the fertiliser industry. Uranium and cadmium contents are higher in carbonate-bearing fluorapatite than magmatic carbonatite apatite, but are much lower than most marine phosphorites.
DS2002-1258
2002
Pickrell, J.Pickrell, J.Gems of war - scientists struggle to identify conflict diamonds.....Diamond dangerScience News, Vol. 162, No. 5, Aug. 10, pp. 90-92.GlobalConflict diamonds
DS1900-0126
1902
Pickstone, W.Pickstone, W.Mining in South Africa: Kimberley and TransvaalManchester Geological Society Transactions, Vol. 27, 1900-1902, PP. 124-132.; ALSO: AUSTRALIAN MIN. STANAfrica, South AfricaHistory
DS1997-0906
1997
Picton, J.Picton, J.Africa and de Beers/Centenary in the world diamond context now, by 2000 andbeyond.World Diamond Conference held Oct '97, Standard Equities, 25p.South Africa, Africa, GlobalDiamond production, Diamond markets, CSO
DS1999-0556
1999
Picton, J.Picton, J.African diamond production in the 21st. CenturyGemological Institute of America (GIA) International Gem. Symposium June 21-24, 16p. slide reprod. 2p. text under slidesAngola, Namibia, Democratic Republic of Congo, Botswana, South AfricaEconomics, Diamond production, Petra Diamonds
DS2003-1075
2003
Picton, J.Picton, J.Market outlook. Supply and productionRough Diamond Review, No. 2, September, pp.28-29.GlobalDiamond markets
DS200412-1546
2003
Picton, J.Picton, J.Market outlook. Supply and production.Rough Diamond Review, No. 2, September, pp.28-29.GlobalDiamond markets
DS1859-0078
1844
Piddington, H.Piddington, H.Examination of a Remarkable Red Sandstone from the Junction of the Diamond Limestone and Sandstone at Nurmoor in the Kurnool Territory, Southern India.Asiatic Soc. Bengal Journal, Vol. 13, PP. 336-338.IndiaGeology
DS1984-0382
1984
Pidgeon, R.Jaques, A.L., Webb, A.W., Fanning, C.M., Black, C.P., Pidgeon, R.The Age of the Diamond Bearing Pipes and Associated LeuciteB.m.r. Journal of Aust. Geol. Geophys., Vol. 9, PP.Australia, Western AustraliaGeochronology, Related Rocks
DS1986-0644
1986
Pidgeon, R.T.Pidgeon, R.T., Smith, C.B., Fanning, C.M.The ages of kimberlite and lamproite emplacement in Western AustraliaProceedings of the Fourth International Kimberlite Conference, Held Perth, Australia, No. 16, pp. 136-138AustraliaLamproite, Geochronology
DS1988-0338
1988
Pidgeon, R.T.Kalsbeek, F., Taylor, P.N., Pidgeon, R.T.Unreworked Archean basement and Proterozoic supracrustal rocks from northeastern Disko Bugt.Canadian Journal of Earth Sciences, Vol. 25, pp. 773-82.GreenlandProterozoic mobile belts
DS1989-1213
1989
Pidgeon, R.T.Pidgeon, R.T.Archean diamond xenocrysts in kimberlites- how definitive is theevidence?Geological Society of Australia Inc. Blackwell Scientific Publishing, Special, No. 14, Vol. 2, pp. 1007-1011South AfricaXenocrysts, Geochronology
DS1989-1214
1989
Pidgeon, R.T.Pidgeon, R.T., Smith, C.B., Fanning, C.M.Kimberlite and lamproite emplacement ages in western AustraliaGeological Society of Australia Inc. Blackwell Scientific Publishing, Special, No. 14, Vol. 1, pp. 369-381AustraliaTectonics, Age emplacement
DS1990-1182
1990
Pidgeon, R.T.Pidgeon, R.T., Wilde, S.A.The distribution of 3.0 Ga and 2.7 Ga volcanic episodes in the Yilgarn Craton of Western Australia.Precambrian Research, Vol. 48, pp. 309-325.AustraliaCraton - Yilgarn, Geochronology
DS1996-0157
1996
Pidgeon, R.T.Bosch, D., Bruguier, O., Pidgeon, R.T.Evolution of an Archean metamorphic belt: a conventional and SHRIMP uranium-lead (U-Pb)study of accessory mineralJournal of Geology, Vol. 104, No. 6, Nov. pp. 695-711AustraliaYilgarn Craton, Jimperding metamorphic belt
DS2000-0538
2000
Pidgeon, R.T.Kroner, A., Hegner, E., Pidgeon, R.T.Age and magmatic history of the Antananrivo Block, central Madagascar: derived from zircon geochronologyAmerican Journal of Science, Vol. 300, No. 4, Apr. pp. 251-88.MadagascarMagmatism, Geochronology - age determinations, isotopic
DS200712-0716
2007
Pidgeon, R.T.Menneken, M., Nemchin, A.A., Geisler, T., Pidgeon, R.T., Wilde, S.A.Oldest terrestrial diamonds in zircon from Jack Hills, Western Australia.Plates, Plumes, and Paradigms, 1p. abstract p. A652.AustraliaJack Hills
DS200712-0717
2007
Pidgeon, R.T.Menneken, M., Newchin, A.A., Geisler, T., Pidgeon, R.T., Wilde, S.A.Hadean diamonds in zircon from Jack Hills, Western Australia.Nature, Vol. 448, August 23, pp. 917-921.Australia, Western AustraliaGeochronology
DS200812-0791
2008
Pidgeon, R.T.Nemchin, A.A., Whitehouse, M.J., Menneken, M., Geisler, T., Pidgeon, R.T., Wilde, S.A.A light carbon reservoir recorded in zircon hosted diamond from the Jack Hills.Nature, Vol. 454m, 7200, July 3, pp. 92-95.AustraliaGeochronology
DS200812-0897
2008
Pidgeon, R.T.Pidgeon, R.T., Nemchin, A.A., Geisler, T.Effects of chemical weathering on the chemical and isotopic signatures of ancient zircons from Jack Hills and Mt. Nattyer, western Australia.Goldschmidt Conference 2008, Abstract p.A747.AustraliaGeochronology
DS1986-0057
1986
PidzyrailoBartoshinskiy, Z.V., Bekesha, S.N., Vinnichenko, T.G., PidzyrailoTypes of photoluminescence spectra of diamonds of Yakutia.(Russian)Mineral. Sbov. (Lvov), (Russian), Vol. 40, No. 1, pp. 32-38RussiaSpectroscopy
DS1990-1183
1990
Piech, K.R.Piech, M.A., Piech, K.R.Fingerprints and fractal terrainMathematical Geology, Vol. 22, No. 4, May pp. 457-486GlobalGeostatistics, Fractal
DS1990-1183
1990
Piech, M.A.Piech, M.A., Piech, K.R.Fingerprints and fractal terrainMathematical Geology, Vol. 22, No. 4, May pp. 457-486GlobalGeostatistics, Fractal
DS2002-1261
2002
Pieczonka, J.Piestrzyski, A., Pieczonka, J., Guszek, A.Redbed type gold mineralization, Kuperschiefer, south West PolandMineralium deposita, PolandGold, metallogeny, zinc, lead, Deposit - Kuperschiefer
DS201112-0796
2011
Piedra, M.M.Piedra, M.M., Haynes, H., Hoey, T.B.The spatial distribution of coarse surface grains and the stability of gravel.Sedimentology, In press availableTechnologyGravel bedforms - not specific to diamonds
DS201112-0797
2011
Piegari, E.Piegari, E., Di Maio, R., Scandone, R., Milano, L.A cellular automaton model for magma ascent: degassing and styles of volcanic eruptions.Journal of Geothermal Volcanology and Research, Vol. 202, 1-2, pp. 22-28.MantleMagmatism
DS200712-0940
2007
Pielke, R.A.Jr.Sarewitz, D., Pielke, R.A.Jr.The neglected heart of science policy: reconciling supply of and demand for science.Environmental Science and Policy, Vol. 10, 1, pp. 5-26.GlobalResearch necessary
DS201907-1566
2016
Piementle, F.Pandit, K., Sial, S., Piementle, F.Geochemistry and C-O and Nd-Sr isotope characteristics of thre 2.4 Ga Higenakkal carbonatites from the South Indian granulite terrane: evidence for an end- Archean depleted component and mantle heterogenity. Note date 2016International Geology Review, Vol. 58, 12, pp. 1461-1480.Indiacarbonatites

Abstract: The South Indian Granulite Terrane (SGT) is a collage of Archaean to Neoproterozoic age granulite facies blocks that are sutured by an anastomosing network of large-scale shear systems. Besides several Neoproterozoic carbonatite complexes emplaced within the Archaean granulites, there are also smaller Paleoproterozoic (2.4 Ga, Hogenakkal) carbonatite intrusions within two NE-trending pyroxenite dikes. The Hogenakkal carbonatites, further discriminated into sövite and silicate sövite, have high Sr and Ba contents and extreme light rare earth element (LREE) enrichment with steep slopes typical of carbonatites. The C- and O-isotopic ratios [?13CVPDB = ?6.7 to ?5.8‰ and ?18OVSMOW = 7.5-8.7‰ except a single 18O-enriched sample (?18O = 20.0‰)] represent unmodified mantle compositions. The ?Nd values indicate two groupings for the Hogenakkal carbonatites; most samples show positive ?Nd values, close to CHUR (?Nd = ?0.35 to 2.94) and named high-?Nd group while the low-?Nd group samples show negative values (?5.69 to ?8.86), corresponding to depleted and enriched source components, respectively. The 87Sr/86Sri ratios of the two groups also can be distinguished: the high-?Nd ones have low 87Sr/86Sri ratios (0.70161-0.70244) while the low-?Nd group shows higher ratios (0.70247-0.70319). We consider the Nd-Sr ratios as primary and infer derivation from a heterogeneous mantle source. The emplacement of the Hogenakkal carbonatites may be related to Paleoproterozoic plume induced large-scale rifting and fracturing related to initiation of break-up of the Neoarchean supercontinent Kenorland.
DS201612-2325
2016
Piementle, M.Pandit, M.K., Kumar, N., Sial, A.N., Sukumaran, G.B., Piementle, M., Ferreira, V.P.Geochemistry and C-O and Nd-Sr isotope characteristics of the 2.4 Ga Hogenakkal carbonatites and the South Indian granulite terrain: evidence for an end Archean depleted component and mantle heterogeneity.International Geology Review, Vol. 58, 12, pp. 1461-1480.IndiaCarbonatite

Abstract: The South Indian Granulite Terrane (SGT) is a collage of Archaean to Neoproterozoic age granulite facies blocks that are sutured by an anastomosing network of large-scale shear systems. Besides several Neoproterozoic carbonatite complexes emplaced within the Archaean granulites, there are also smaller Paleoproterozoic (2.4 Ga, Hogenakkal) carbonatite intrusions within two NE-trending pyroxenite dikes. The Hogenakkal carbonatites, further discriminated into sövite and silicate sövite, have high Sr and Ba contents and extreme light rare earth element (LREE) enrichment with steep slopes typical of carbonatites. The C- and O-isotopic ratios [?13CVPDB = ?6.7 to ?5.8‰ and ?18OVSMOW = 7.5-8.7‰ except a single 18O-enriched sample (?18O = 20.0‰)] represent unmodified mantle compositions. The ?Nd values indicate two groupings for the Hogenakkal carbonatites; most samples show positive ?Nd values, close to CHUR (?Nd = ?0.35 to 2.94) and named high-?Nd group while the low-?Nd group samples show negative values (?5.69 to ?8.86), corresponding to depleted and enriched source components, respectively. The 87Sr/86Sri ratios of the two groups also can be distinguished: the high-?Nd ones have low 87Sr/86Sri ratios (0.70161-0.70244) while the low-?Nd group shows higher ratios (0.70247-0.70319). We consider the Nd-Sr ratios as primary and infer derivation from a heterogeneous mantle source. The emplacement of the Hogenakkal carbonatites may be related to Paleoproterozoic plume induced large-scale rifting and fracturing related to initiation of break-up of the Neoarchean supercontinent Kenorland.
DS200612-0850
2005
Pienaar, C.Maier, W.D., Peltonen, P., Juvonen, R., Pienaar, C.Platinum group elements in peridotite xenoliths and kimberlite from the Premier kimberlite pipe, South Africa.South African Journal of Geology, Vol. 108, pp. 413-428.Africa, South AfricaDeposit - Premier, xenolith mineralogy
DS2003-1076
2003
Pienaar, C.I.L.Pienaar, C.I.L., Kelly, C.L.Diamond growth histories at Premier mine8ikc, Www.venuewest.com/8ikc/program.htm, Session 3, POSTER abstractSouth AfricaDiamonds, Deposit - Premier
DS1991-1352
1991
Pienaar, H.Pienaar, H., Glenister, D.A.On a gift of diamonds from Cecil John Rhodes for services renderedXiii International Gemmological Conference Held South Africa, Stellenbosch, 2p.abstractSouth AfricaHistory, Diamond gift to Heathcliffe
DS1989-0031
1989
Pier, J.G.Aranda-Gomez, J.J., Luhr, J.F., Pier, J.G.Petrology and geochemistry of basanitic rocks from the la Brena and ElJagury Maar complex, Durango, MexicoGeological Society of America (GSA) Annual Meeting Abstracts, Vol. 21, No. 6, p. A201. AbstractMexicoBasanite, Petrology
DS201312-0670
2012
Pierazzo, E.Osinski, G.R., Pierazzo, E.Impact cratering: processes and products.Wiley Blackwell, 330p. Approx. $ 145.MantleCrater
DS200812-0536
2008
Piercey, S.Kamber, B.S., Mohan, M.R., Piercey, S.Fluid mobile elements in evolved Archean magmas: implications for Archean subduction processes.Goldschmidt Conference 2008, Abstract p.A446.MantleSubduction
DS2001-0921
2001
Piercey, S.J.Piercey, S.J., Murphy, D.C., Mortensen, J.K., ParadisBoninitic magmatism in a continental margin setting, Yukon Tanana TerraneGeology, Vol. 29, No. 8, Aug. pp. 731-4.YukonBoninites, Magmatism - geochemistry
DS2002-1259
2002
Piercey, S.J.Piercey, S.J., Mortensen, J.K., Murphy, D.C., Paradis, S., Creaser, R.A.Geochemistry and tectonic significance of alkalic mafic magmatism in the Ykun Tanana terrane, Finlayson Lake region, Yukon.Canadian Journal of Earth Sciences, Vol. 39, 12, Dec. pp. 1729-44.YukonTectonics
DS2002-1260
2002
Piercey, S.J.Piercey, S.J., Mortensen, J.K., Murphy, D.C., Paradis, S., Creaser, R.A.Geochemistry and tectonic significance of alkalic mafic magmatism in the Yukon Tanana terrane, Finlayson Lake region, Yukon.Canadian Journal of Earth Sciences, Vol. 39, 12, Dec. pp. 1729-44.YukonMagmatism
DS201908-1778
2019
Pierotti, C.Hao, M., Pierotti, C., Tkachev, S., Prakapenka, V., Zhang, J.The anisotropic omphacite in the Earth's upper mantle: implications for detecting eclogitic materials inside the Earth.www.minsocam.org /MSA/Centennial/ MSA_Centennial _Symposium.html The next 100 years of mineral science, June 20-21, p. 27. AbstractMantleeclogites

Abstract: Omphacite is a clinopyroxene solid solution of Fe-bearing diopside and jadeite, and is stable up to about 500 km depth in the Earth’s interior. It is also a major mineral component of eclogite (up to 75 vol%). Basalt, which makes up most of the Earth’s oceanic crust, transforms into eclogite at the depth > ~60 km. Due to the ~20% higher density of eclogite, it is considered one of the main driving forces for the slab subduction. Subducted eclogite is also an important source of the chemical heterogeneities in the Earth’s mantle, which are the potential reservoirs for the enriched geochemical components. Thus, studying the geophysical properties of omphacite at elevated pressure-temperature conditions is of great interest for both the geophysical and geochemical community. Previous studies have proposed to utilize the unique anisotropic seismic properties of eclogite to identify possible subduction channels and eclogite-rich regions in the Earth’s interior. Due to the elastically isotropic nature of garnet and the relatively small proportion (< 10 vol%) of the silica minerals in eclogite, the seismic anisotropy of eclogite is primarily caused by the lattice preferred orientation of omphacite. Thus, in this study, in addition to determining the densities, and isotropic velocities of omphacite at the high pressuretemperature condition, we also paid special attention to the elastic anisotropy of omphacite. We combined the synchrotron single-crystal X-ray diffraction at Advanced Photon Source, Argonne National Laboratory with offline Brillouin spectroscopy experiments at University New Mexico to investigate the anisotropic thermoelastic properties of omphacite. Incorporated with the preexisting thermoelastic database of other relevant mantle mineral phases, we compared the anisotropic seismic properties of eclogite (slab crust) with pyrolite (ambient mantle) along mantle geotherms down to 500 km depth. The maximum isotropic and anisotropic velocities contrast between pyrolite and eclogite is at 310-410 km, making it an optimal depth range for seismologists to search for eclogite-rich heterogeneities in the Earth’s interior. The ~5%-7% velocity difference between eclogite and pyrolite also needs to be taken into account when estimating the slab temperatures between 310-410 km depth. Otherwise, the slab temperature could be underestimated by a few hundred K without considering the possible lithology difference.
DS201809-2005
2017
Pierre, S.Cassette, P., Notari, F., Lepy, M-C., Caplan, C., Pierre, S., Hainschwang, T., Fritsch, E.Residual radioactivity of treated green diamonds.Applied Radiation and Isotopes, Vol. 126, 1, pp. 66-72.Globaldiamond - green

Abstract: Treated green diamonds can show residual radioactivity, generally due to immersion in radium salts. We report various activity measurements on two radioactive diamonds. The activity was characterized by alpha and gamma ray spectrometry, and the radon emanation was measured by alpha counting of a frozen source. Even when no residual radium contamination can be identified, measurable alpha and high-energy beta emissions could be detected. The potential health impact of radioactive diamonds and their status with regard to the regulatory policy for radioactive products are discussed.
DS200512-0854
2005
Pierrehumbert, R.T.Pierrehumbert, R.T.Climate dynamics of a hard snowball Earth.Journal of Geophysical Research, Vol. 110, D1 D01111Climate
DS201908-1781
2019
Pierrehumbert, R.T.Jellinek, A.M., Lenardic, A., Pierrehumbert, R.T.Ice, fire or fizzle: the climate footprint of Earth's supercontinental cycles.Geochemistry, Geophysics, Geosystems, in press, 59p. PdfMantleNuna
DS202003-0343
2020
Pierrehumbert, R.T.Jellinek, M., Lenardic, A., Pierrehumbert, R.T.Ice, fire, or fizzle: the climate footprint of Earth's supercontinental cycles.Geochemistry, Geophysics, Geosystems, Vol. 21, 2, 66p. PdfMantlegeodynamics

Abstract: Supercontinent assembly and breakup can influence the rate and global extent to which insulated and relatively warm subcontinental mantle is mixed globally, potentially introducing lateral oceanic?continental mantle temperature variations that regulate volcanic and weathering controls on Earth's long?term carbon cycle for a few hundred million years. We propose that the relatively warm and unchanging climate of the Nuna supercontinental epoch (1.81.3 Ga) is characteristic of thorough mantle thermal mixing. By contrast, the extreme cooling?warming climate variability of the Neoproterozoic Rodinia episode (10.63 Ga) and the more modest but similar climate change during the Mesozoic Pangea cycle (0.30.05 Ga) are characteristic features of the effects of subcontinental mantle thermal isolation with differing longevity. A tectonically modulated carbon cycle model coupled to a one?dimensional energy balance climate model predicts the qualitative form of Mesozoic climate evolution expressed in tropical sea?surface temperature and ice sheet proxy data. Applied to the Neoproterozoic, this supercontinental control can drive Earth into, as well as out of, a continuous or intermittently panglacial climate, consistent with aspects of proxy data for the Cryogenian?Ediacaran period. The timing and magnitude of this cooling?warming climate variability depends, however, on the detailed character of mantle thermal mixing, which is incompletely constrained. We show also that the predominant modes of chemical weathering and a tectonically paced abiotic methane production at mid?ocean ridges can modulate the intensity of this climate change. For the Nuna epoch, the model predicts a relatively warm and ice?free climate related to mantle dynamics potentially consistent with the intense anorogenic magmatism of this period.
DS1989-1215
1989
Pierrot, R.M.Pierrot, R.M., et al.Chemical and determinative tables of mineralogy, silicatesFrench Geological Survey (BRGM)., 308p. approx. 700ffGlobalMineralogy -silicates, Book review
DS1993-1374
1993
Pierson, C.T.Sanford, R.F., Pierson, C.T., Crovelli, R.A.An objective replacement method for censored geochemical dataMathematical Geology, Vol. 25, No. 1, pp. 59-80GlobalGeochemistry, Environmental
DS1992-1700
1992
Pierson, T.C.Wright, T.L., Pierson, T.C.Living with volcanoesUnited States Geological Survey (USGS) Circular, No. 1073, 57pUnited StatesVolcanoes, Research
DS1993-0020
1993
Pieruccini, U.Alberti, A., Alessandro, V., Pieruccini, U., Pranzini, E.Land sat Thematic Mapperdat a processing for lithological discrimination in the Caraculoarea (Namibe Province, southwest Angola).Journal of African Earth Sciences, Vol. 17, No. 3, October pp. 261-274.AngolaLandsat -not specific to diamonds, Remote sensing, lithology
DS2001-0922
2001
Piestrzynski, A.Piestrzynski, A., et al.Mineral deposits at the beginning of the 21st. century. Proceedings 6th. Biennial SGA SEG meeting Poland in August.Balkema Publishing, 1180p. approx. $ 210.00GlobalBook - ad, Mineral deposits
DS2002-1261
2002
Piestrzyski, A.Piestrzyski, A., Pieczonka, J., Guszek, A.Redbed type gold mineralization, Kuperschiefer, south West PolandMineralium deposita, PolandGold, metallogeny, zinc, lead, Deposit - Kuperschiefer
DS201611-2131
2016
Piet, H.Piet, H., Badro, J., Nabiei, F., Gillet, P.Spin and valence dependence of iron partitioning in Earth's deep mantle.Proceedings of National Academy of Science USA, Vol. 113, 40, pp. 11127-11130.MantleIron

Abstract: We performed laser-heated diamond anvil cell experiments combined with state-of-the-art electron microanalysis (focused ion beam and aberration-corrected transmission electron microscopy) to study the distribution and valence of iron in Earth’s lower mantle as a function of depth and composition. Our data reconcile the apparently discrepant existing dataset, by clarifying the effects of spin (high/low) and valence (ferrous/ferric) states on iron partitioning in the deep mantle. In aluminum-bearing compositions relevant to Earth’s mantle, iron concentration in silicates drops above 70 GPa before increasing up to 110 GPa with a minimum at 85 GPa; it then dramatically drops in the postperovskite stability field above 116 GPa. This compositional variation should strengthen the lowermost mantle between 1,800 km depth and 2,000 km depth, and weaken it between 2,000 km depth and the D” layer. The succession of layers could dynamically decouple the mantle above 2,000 km from the lowermost mantle, and provide a rheological basis for the stabilization and nonentrainment of large low-shear-velocity provinces below that depth.
DS201701-0026
2016
Piet, H.Piet, H., Badro, J., Nabiel, F., Dennenwaldt, T., Shim, S-H., Cantoni, M., Hebert, C., Gillet, P.Spin and valence dependence on iron partitioning in Earth's deep mantle.Proceedings of National Academy of Science USA, Vol. 113, no. 40, pp. 11127-11130.MantleUHP

Abstract: We performed laser-heated diamond anvil cell experiments combined with state-of-the-art electron microanalysis (focused ion beam and aberration-corrected transmission electron microscopy) to study the distribution and valence of iron in Earth's lower mantle as a function of depth and composition. Our data reconcile the apparently discrepant existing dataset, by clarifying the effects of spin (high/low) and valence (ferrous/ferric) states on iron partitioning in the deep mantle. In aluminum-bearing compositions relevant to Earth's mantle, iron concentration in silicates drops above 70 GPa before increasing up to 110 GPa with a minimum at 85 GPa; it then dramatically drops in the postperovskite stability field above 116 GPa. This compositional variation should strengthen the lowermost mantle between 1,800 km depth and 2,000 km depth, and weaken it between 2,000 km depth and the D" layer. The succession of layers could dynamically decouple the mantle above 2,000 km from the lowermost mantle, and provide a rheological basis for the stabilization and nonentrainment of large low-shear-velocity provinces below that depth.
DS202002-0204
2019
Piet, H.Lobanov, S.S., Holtgrewe, N., Ito, G., Badro, J., Piet, H., Babiel, F., Lin, J-F., Bayarjargal, L., Wirth, R., Schrieber, A., Goncharov, A.F.Blocked radiative heat transport in the hot pyrolitic lower mantle.Researchgate.com, 32p. PdfMantlegeothermometry

Abstract: The heat flux across the core-mantle boundary (QCMB) is the key parameter to understand the Earth/s thermal history and evolution. Mineralogical constraints of the QCMB require deciphering contributions of the lattice and radiative components to the thermal conductivity at high pressure and temperature in lower mantle phases with depth-dependent composition. Here we determine the radiative conductivity (krad) of a realistic lower mantle (pyrolite) in situ using an ultra-bright light probe and fast time-resolved spectroscopic techniques in laser-heated diamond anvil cells. We find that the mantle opacity increases critically upon heating to ~3000 K at 40-135 GPa, resulting in an unexpectedly low radiative conductivity decreasing with depth from ~0.8 W/m/K at 1000 km to ~0.35 W/m/K at the CMB, the latter being ~30 times smaller than the estimated lattice thermal conductivity at such conditions. Thus, radiative heat transport is blocked due to an increased optical absorption in the hot lower mantle resulting in a moderate CMB heat flow of ~8.5 TW, at odds with present estimates based on the mantle and core dynamics. This moderate rate of core cooling implies an inner core age of about 1 Gy and is compatible with both thermally- and compositionally-driven ancient geodynamo.
DS1986-0589
1986
Pieters, C.M.Mustard, J.F., Pieters, C.M.Erosion of kimberlite during eruption of Moses Rock dike #1Eos, Vol. 67, No. 44, Nov. 4th. p. 1073. (abstract.)ColoradoBlank
DS1986-0590
1986
Pieters, C.M.Mustard, J.F., Pieters, C.M.Erosion of kimberlite during eruption of Moses Rock dike #2Eos, Vol. 67, No. 44, p. 1073UtahKimberlite, Remote Sensing
DS1987-0498
1987
Pieters, C.M.Mustard, J.F., Pieters, C.M.Quantitative abundance estimates from bidirectional reflectancemeasurementsJournal of Geophysical Research, Vol. 92, No. B4, pp. E617-E526GlobalRemote Sensing, Kimberlite
DS1987-0499
1987
Pieters, C.M.Mustard, J.F., Pieters, C.M.Variations in composition of kimberlite dike matrix examined with mapping spectrometer data18th. Lunar And Planetary Science Conference, Vol. 28, pt. 2, pp. 688-689. (abstract.)UtahRemote sensing, Spectrometer
DS1993-1236
1993
Pieters, C.M.Pieters, C.M., Englert, P.A.J.Remote geochemical analysis.. elemental and mineralogical compositionCambridge Press, 585p. approx. $ 75.00GlobalBook -ad, Geochemical analysis
DS1993-1237
1993
Pieters, C.M.Pieters, C.M., Englert, P.A.J.Remote geochemical analysis: elemental and mineralogical compositionCambridge University Press, Chapters 1-3 outlinedGlobalBook -table of contents, Geochemistry
DS1993-1238
1993
Pieters, C.M.Pieters, C.M., Englert, P.A.J.Imaging spectroscopy... Moses Rock Dike, Utah: AIS mantlecomposition/tectonics.In: Remote geochemical analysis: elemental and mineralogical, pp. 299-301.UtahSpectroscopy, Moses Rock Dike
DS200612-0700
2006
Pieters, C.M.Kilma, R.L., Pieters, C.M.Near and mid-infrared micro spectroscopy of the Ronda peridotite.Journal of Geophysical Research, Vol. 111, E1. 10.1029/2005 JE002537Europe, SpainPeridotite
DS1990-0788
1990
Pietgen, H-O.Jurgens, H., Pietgen, H-O., Saupe, D.The language of fractalsScientific American, Vol. 263, No. 2, August pp. 60-67GlobalFractals, Layman's overview
DS200912-0287
2009
Pietranik, A.Hawkesworth, C., Storey, C., Dhuime, B., Marschall, H., Pietranik, A., Kemp, T.The generation, evolution and preservation of the continental crust.Goldschmidt Conference 2009, p. A505 Abstract.MantleZircon geochronology
DS200812-0898
2008
Pietranik, A.BPietranik, A.B, Hawkesworth, C.J., Storey, C.D., Kemp, T.I.S., Sircombe, Whitehouse, BleekerEpisodic, mafic crust formation in the Slave Craton, Canada.Goldschmidt Conference 2008, Abstract p.A748.Canada, Northwest TerritoriesMantle zircons
DS200812-0899
2008
Pietranik, A.B.Pietranik, A.B., Hawkesworth, C.J., Storey, C.D., Kemp, A.I.S., Sircombe, K.N., Whitehouse, M.J., Bleeker, W.Episodic mafic crust formation from 4.5 to 2.8 Ga: new evidence from detrital zircons, Slave craton, Canada.Geology, Vol. 36, 11, pp. 875-878.Canada, Northwest TerritoriesGeochronology
DS201012-0271
2010
Pietranik, A.B.Hawkesworth, C.J.,Dhuime, B., Pietranik, A.B., Cawood, P.A., kemp, A.I.S., Storey, C.D.The generation and evolution of the continental crust.Journal of the Geological Society, Vol. 167, 3, March pp. 229-248.MantleReview
DS1940-0158
1947
Pifer, D.A.Pifer, D.A.Sampling Diamond Deposits in Southern AfricaEngineering and Mining Journal, Vol. 148, PP. 78-81.Southwest Africa, NamibiaMining Methods, Littoral Diamond Placers
DS1860-0158
1871
Piggot, J.Piggot, J.South African Diamonds (1871)Journal of Arts Society, NEW SER., Vol. 10, P. 117.Africa, South Africa, Cape ProvinceHistory
DS1980-0290
1980
Pighin, D.L.Roberts, M.A., Skall, H., Pighin, D.L.Diatremes in the Rocky Mountains of Southeastern British Columbia.The Canadian Mining and Metallurgical Bulletin (CIM Bulletin) ., Vol. 73, No. 821, PP. 74-75. (abstract.).Canada, British ColumbiaDiatreme
DS201504-0212
2015
Pigott, J.S.Panero, W.R., Pigott, J.S., Reaman, D.M., Kabbes, J.E., Liu, Z.Dry ( Mg,Fe) SiO3 perovskite in the Earth's lower mantle.Journal of Geophysical Research, Vol. 120, 2, pp. 894-908.MantlePerovskite
DS201012-0584
2009
Piip, V.B.Piip, V.B.Structure of the Siberian upper mantle from superlong seismic profile data.Moscow University Geology Bulletin, Vol. 64, 5, Oct. pp. 296-305.RussiaGeophysics - seismics
DS201811-2601
2018
Piispa, E.J.Piispa, E.J., Smirnov, A.V., Pesonen, L.J., Mitchell, R.H.Paleomagnetism and geochemistry of ~1144.-Ma lamprophyre dikes, northwestern Ontario: implcations for the North American polar wander and plate velocities.Journal of Geophysical Research: Solid Earth, Vol. 123, 8, pp. 6195-6214.Canada, Ontariogeochronology

Abstract: Similar to a magnetic tape, rocks can retain the direction of ancient Earth's magnetic field. Scientists use this record (known as paleomagnetism) to reconstruct past positions of continents and to decipher the geological history of our planet. We investigated paleomagnetism and chemical composition of the ~1.14 Ga?old intrusive rocks called lamprophyres exposed in Northwestern Ontario (Canada). We found that the paleomagnetic field directions recorded in lamprophyres are indistinguishable from those recorded by another similar age suite of basaltic intrusions called the Abitibi dikes, from the same area. The combined data from these rocks allowed us to constrain the position of an ancient supercontinent called Laurentia at ~1.14 billions of years ago more accurately than it was possible before. Our results convincingly show that, during that time, Laurentia moved with a velocity comparable to present?day plate velocities, before switching to an extremely rapid motion approximately 35 millions of years later. The lamprophyre and Abitibi rocks also share similar chemical signatures, close to those observed for ocean island basalts (e.g., Hawaii). These observations support the hypothesis that a failed ocean opening attempt called the North American Midcontinent Rift was instigated by the arrival of a hot mantle material upwelling to the Earth surface.
DS201901-0071
2018
Piispa, E.J.Salminen, J., Oliveira, E.P., Piispa, E.J., Smirnov, A.V., Trindade, R.I.F.Revisiting the paleomagnetism of the Neoarchean Uaua mafic dyke swarm, Brazil: implications for Archean supercratons.Precambrian Research, doi.org/10.1016/j. precamres.2018.12.001 17p. South America, Brazilcraton

Abstract: The original connections of Archean cratons are becoming traceable due to an increasing amount of paleomagnetic data and refined magmatic barcodes. The Uauá block of the northern São Francisco craton may represent a fragment of a major Archean craton. Here, we report new paleomagnetic data from the 2.62 Ga Uauá tholeiitic mafic dyke swarm of the Uauá block in the northern São Francisco craton, Eastern Brazil. Our paleomagnetic results confirm the earlier results for these units, but our interpretation differs. We suggest that the obtained characteristic remanent magnetization for the 2.62 Ga swarm is of primary origin, supported by a provisionally-positive baked contact test. The corresponding paleomagnetic pole (25.2°N, 330.5°E, A95 = 8.1° N = 20) takes the present northern part of the São Francisco craton to moderate latitudes. Based on the comparison of the paleolatitudes of cratons with high-quality paleomagnetic data and magmatic barcodes, we suggest that the northern part of the São Francisco craton could have been part of the proposed Supervaalbara supercraton during the Archean. Supervaalbara is proposed as including (but not limited to) the part of the São Francisco craton as well as the Superior, Wyoming, Kola + Karelia, Zimbabwe, Kaapvaal, Tanzania, Yilgarn, and Pilbara cratons.
DS200612-1088
2005
Pik, R.Pik, R., Marty, B., Hilton, D.R.How many mantle plumes in Africa? The geochemical point of view.Chemical Geology, Vol. 226, 3-4, pp. 100-114.AfricaAfrican plate, Hoggar, Tibesti, Darfur, Ethiopia, Kenya
DS200812-0761
2007
Pik, R.Montagner, J.P., Marty, B., Stutzmann, E., Sicilia, D., Cara, M., Pik, R., Leveque, Roult, Beucier, DeBayleMantle upwellings and convective instabilities revealed by seismic tomography and helium isotope geochemistry beneath eastern Africa.Geophysical Research Letters, Vol. 34, 21, Nov. 16, ppp. L21303.AfricaConvection
DS1987-0490
1987
Pike, C.J.Morel -A-Lhuissier, P., Green, A.G., Pike, C.J.Crustal refraction surveys across the Trans Hudson orogen/Williston Basin of South Central CanadaJournal of Geophysical Research, Vol. 92, No. B7, June 10, pp. 6403-6420CanadaSaskatchewan, Geophysics
DS1980-0281
1980
Pike, J.E.N.Pike, J.E.N., Meyer, H.O.A., Wilshire, H.G.Petrography and Chemical Composition of a Suite of Ultramafic Xenoliths from Lashaine Tanzania.Journal of GEOLOGY, Vol. 88, No. 3, PP. 343-352.Tanzania, East AfricaPetrography
DS1991-1353
1991
Pike, R.J.Pike, R.J.Surface features of central North America: a synoptic view from computergraphicsGsa Today, Vol. 1, No. 11, November pp. 241, 251-253MidcontinentComputer graphics, Brief overview
DS1991-1712
1991
Pike, R.J.Thelin, G.P., Pike, R.J.Landforms of the conterminous United States: a digital shaded reliefportrayal.Miscellaneous investigation map seriesUnited States Geological Survey (USGS) Map and text, 1: 3, 500, 000 16p. $ 5.00United StatesMap, Digital relief
DS1993-1239
1993
Pike, R.J.Pike, R.J.A bibliography of geomorphometry with a topical key to the literature and an introduction to the numerical characterization of topographic forM.United States Geological Survey (USGS) Open File, No. 93-0262-A, 132p. $ 20.00 plus disc $ 10.00United StatesGeomorphology, Bibliography
DS1990-1344
1990
Pikovskiy, Yu.I.Shepeleva, N.N., Ogloblina, A.I., Pikovskiy, Yu.I.Polycyclic aromatic hydrocarbons in carbonaceous material from the Daldyn-Alakit region, Siberian PlatformGeochemical Int, Vol. 27, No. 3, pp. 98-107RussiaKimberlite, Carbonaceous material
DS200612-0685
2006
Piladou, S.Kendall, J.M., Piladou, S., Keir, D., Bastow, I.D., Stuart, G.W., Ayele, A.Mantle upwellings, melt migration and the rifting of Africa: insights from seismic anisotropy.Geological Society of London, Special Publication, No. 259, pp. 55-72.AfricaTectonics
DS1997-0446
1997
Pilant, A.D.Griffiths, J.C., Pilant, A.D., Smith, C.M.Quantitative assessment of the geology of large regions and their application to mineral resource assessmentNonrenewable Resources, Vol. 6, No. 3, Sept. pp. 157-236GlobalPetrographic index, mineral resource values, classification, reserves, geostatistics
DS2002-0830
2002
Pilatasig, L.F.Kerr, A.C., Aspden, J.A., Tarney, J., Pilatasig, L.F.The nature and provenance of accreted oceanic terranes in western Ecuador: geochemical and tectonic constraints.Journal of the Geological Society of London, Vol. 159, 5, pp. 577-594.EcuadorBlank
DS200412-0988
2002
Pilatasig, L.F.Kerr, A.C., Aspden, J.A., Tarney, J., Pilatasig, L.F.The nature and provenance of accreted oceanic terranes in western Ecuador: geochemical and tectonic constraints.Journal of the Geological Society, Vol. 159, 5, pp. 577-594.South America, EcuadorGeochemistry, tectonics
DS201112-0798
2011
Pilbeam, L.Pilbeam, L., Nielsen, T.F.D., Waight, T.Melt compositions and processes in the kimberlite province of southern West Greenland.Goldschmidt Conference 2011, abstract p.1643.Europe, GreenlandManitsoq
DS201312-0706
2013
Pilbeam, L.H.Pilbeam, L.H., Nielsen, T.F.D., Waight, T.E.Digestion fractional crystallization (DFC): an important process in the genesis of kimberlites. Evidence from olivine in the Majuagaa kimberlite, southern West Greenland.Journal of Petrology, Vol. 54, 7, July pp. 1399-1425.Europe, GreenlandDeposit - Majuagaa
DS1997-0907
1997
Pilchin, A.Pilchin, A., Epplebau, L.Determination of the lower edges of magnetized bodies by using geothermaldata.Geophys. Journal of International, Vol. 128, No. 1, Jan. pp. 167-174.GlobalGeophysics - magnetics, Geothermal
DS1997-0908
1997
Pilchin, A.Pilchin, A., Pilchin, M.Carbonatites as indicator of peridotite formation and periods of ophioliteactivity.Geological Association of Canada (GAC) Abstracts, POSTER.GlobalCarbonatite, Ophiolites
DS2002-1262
2002
Pilchin, A.Pilchin, A., Pilchin, M.Formation of high pressure and low temperature metamorphic rocks an indicator of compression tectonicGac/mac Annual Meeting, Saskatoon, Abstract Volume, P.92., p.92.GlobalEclogites - thermdynamics
DS2002-1263
2002
Pilchin, A.Pilchin, A., Pilchin, M.Formation of high pressure and low temperature metamorphic rocks an indicator of compression tectonicGac/mac Annual Meeting, Saskatoon, Abstract Volume, P.92., p.92.GlobalEclogites - thermdynamics
DS200512-0855
2005
Pilchin, A.Pilchin, A.On the role of tectonic factor in formation of ultra high pressure minerals; one example of coesite.GAC Annual Meeting Halifax May 15-19, Abstract 1p.Europe, GreenlandGeothermometry, eclogite
DS200512-0856
2005
Pilchin, A.Pilchin, A.The role of serpentinization in exhumation of high to ultra high pressure metamorphic rocks.Earth and Planetary Science Letters, Vol. 237, 3-4, Sept. 15, pp. 815-828.TechnologyUHP
DS200512-0857
2005
Pilchin, A.Pilchin, A., Pilchin, M.Some features of garnet and eclogite stability.GAC Annual Meeting Halifax May 15-19, Abstract 1p.MantleGeothermometry, eclogite
DS201702-0213
2017
Pilchin, A.Eppelbaum, L., Kutasov, I., Pilchin, A.Markers of thermal conditions within lithosphere. Lecture Notes in Earth Science Systems, Pt. 6.4, 51p. pdfMantleGeothermometry
DS201705-0871
2017
Pilchin, A.Pilchin, A., Eppelbaum, L.V.Concentration of PGE during the Early Earth evolution: a review.Natural Resources Forum, Vol. 8, pp. 172-233.MantleMineralogy

Abstract: Numerous unique geological processes [1] took place during the early Earth evolution; several of them, especially those occurring in the Hadean—Early Archean and later, are reflected in the modern geological (geophysical, geochemical, etc.) pattern. One such significant enigmatic feature is the preservation of extremely dense and heavy platinum group elements (PGEs): Pt, Pd, Rh, Ru, Ir, Os. Concentration of PGEs during this period could have taken place in two ways: 1) presence of particular matter capable of preserving PGEs near the earth's surface, 2) transportation of PGEs by magma flows from deep lithospheric (asthenospheric) layers (slabs) to the subsurface. Clearly, much of the dense and heavy PGEs did not sink through to the Earth’s mantle (core) at the time of the magma-ocean, and occur near Earth’s surface in abundances for formation of ore deposits with PGE concentrations found to be 2 - 3 orders of magnitude greater than those in their host media. Their enrichments are associated in numerous cases with such enigmatic phenomena as formation of anorthosites and anorthosite-bearing layered magmatic intrusions. PGE deposits and mineralization zones are also found in associations with chromitites, dunites and serpentinites. In this review, problems related to the initial concentration and preservation of PGEs, their association with anorthosites, and formation of layered intrusions are discussed in detail. The main aim of this article is analysis of the requirements—initial concentration and preservation of PGE and PGM (Platinum Group Minerals) during the early Earth evolution, as well as examination of the distribution behavior of some PGEs in different ore deposits and meteorites. It is supposed that meteoritic bombardment of Earth has played a significant role in formation of PGEs deposits. Some conclusions made in this article may be useful for developing and enhancing strategies of prospecting for PGEs deposits.
DS202101-0028
2020
Pilchin, A.N.Pilchin, A.N., Eppelbaum, L.V.Plate tectonics and Earth evolution: a conceptual review.ANAS Transactions, Earth Sciences, Vol. 2, pp. 3-32. pdf doi: 10.33677 /ggianas20200200043Mantlegeodynamics

Abstract: Numerous attempts have been made to understand the rules of Earth’s tectono-geodynamic processes over the past centuries. While no paradigm has offered comprehensive answers to all of the questions, the present review aims to acquaint readers with the modern state of developments in the tectonic insights of Earth's evolution. A number of very interesting and unique processes and features took place during the evolution of early Earth. Most of these, however, were largely erased over the course of Earth’s ensuing evolution; some leaving only traces of their existence and some remnant phenomena, especially those taking place in the Hadean and Early to Late Archean. Among such processes and features are: the planetary accretion of Earth, formation of unique rock complexes, initiation of the plate tectonics phenomenon, main forces driving plate tectonics, significant influence of thermal parameters, role of overpressure under different physical-geological environments, stratification of Earth's crust and lithosphere by density, and various other thermodynamic models. Nearly all of these remain enigmatic, due to considerable uncertainty in the timing and methods of their evolution, and the ambiguity of their secondary processes and tectono-geophysical indicators. At the same time, majority of tectono-geodynamic processes and features are also interrelated, and the simultaneous fluctuation of myriad different factors played a significant role in their influence to the geological medium. Some of these intricate questions are discussed in this paper. For instance, what is the role of the plate tectonics phenomenon and when did this process initiate on Earth? Especial attention is paid in the review to the sophisticated methods of understanding tectonic processes over the course of various generations of geoscientists. In the conducted analyses, certain physical data derived from other planets of the Solar System were utilized as well.
DS1997-0908
1997
Pilchin, M.Pilchin, A., Pilchin, M.Carbonatites as indicator of peridotite formation and periods of ophioliteactivity.Geological Association of Canada (GAC) Abstracts, POSTER.GlobalCarbonatite, Ophiolites
DS2002-1262
2002
Pilchin, M.Pilchin, A., Pilchin, M.Formation of high pressure and low temperature metamorphic rocks an indicator of compression tectonicGac/mac Annual Meeting, Saskatoon, Abstract Volume, P.92., p.92.GlobalEclogites - thermdynamics
DS2002-1263
2002
Pilchin, M.Pilchin, A., Pilchin, M.Formation of high pressure and low temperature metamorphic rocks an indicator of compression tectonicGac/mac Annual Meeting, Saskatoon, Abstract Volume, P.92., p.92.GlobalEclogites - thermdynamics
DS200512-0857
2005
Pilchin, M.Pilchin, A., Pilchin, M.Some features of garnet and eclogite stability.GAC Annual Meeting Halifax May 15-19, Abstract 1p.MantleGeothermometry, eclogite
DS2002-1264
2002
Pilet, S.Pilet, S., Hernandez, J., Villemant, B.Evidence for high silicic melt circulation and metasomatic events in the mantle beneath alkaline provinces: the Na Fe augitic green core pyroxenes.Mineralogy and Petrology, Vol. 76, 1-2, pp.39-62.French Massif CentralTertiary alkali basalts
DS200412-1547
2004
Pilet, S.Pilet, S., Hernandez, J., Sylvester, P.J.Isotopic signature in OIB mantle sources: the metasomatic alternative.Geochimica et Cosmochimica Acta, 13th Goldschmidt Conference held Copenhagen Denmark, Vol. 68, 11 Supp. July, ABSTRACT p.A556.MantleMetasomatism
DS200512-0858
2005
Pilet, S.Pilet, S., Hernadez, J., Sylvester, P., Poujol, M.The metasomatic alternative for ocean island basalt chemical heterogeneity.Earth and Planetary Science Letters, Advanced in press,MantleSubduction, metasomatism
DS200812-0900
2008
Pilet, S.Pilet,S., Baker, M.B., Stolper, E.M.Metasomatized lithosphere and the origin of alkaline lavas.Science, Vol. 320, 5878 May 16, pp. 916-919.MantleRecycled oceanic crust - melting
DS201012-0585
2009
Pilet, S.Pilet, S., Ulmer, P., Villiger, S.Liquid line of descent of a basanitic liquid at 1.5 Gpa: constraints on the formation of metasomatic veins.Contributions to Mineralogy and Petrology, In press formatted available 23p.TechnologyMetasomatism
DS201112-0799
2011
Pilet, S.Pilet, S., Baker, M.B., Muntener, O., Stolper, E.M.Simulations of metasomatic enrichment in the lithosphere and implications for the source of alkaline basalts.Journal of Petrology, Vol. 52, 7-8, pp. 1415-1442.MantleMetasomatism
DS201511-1867
2015
Pilet, S.Pilet, S.Generation of low-silica alkaline lavas: petrological constraints, models, and thermal implications.Geological Society of America Special Paper, No. 514, pp. SPE14-17.MantleMelting, metasomatism

Abstract: Various hypotheses for the origin of alkaline sodic mafic magmas have been proposed. This diversity of models is mainly related to the various constraints used to develop them. The goal of this paper is to test these different models using petrological and geochemical constraints in an attempt to understand why alkaline sodic rocks are so similar even while their environment of formation varies from oceanic to continental rift. Incompatible trace-element contents of alkaline basalts from ocean islands and continents show that the sources of these rocks are more enriched than primitive mantle. A fundamental question then is how the sources of alkaline rocks acquire these trace-element enrichments. Recycled oceanic crust, with or without sediment, is often invoked as a source component of alkaline magmas to account for their trace-element and isotopic characteristics. However, the fact that melting of oceanic crust produces silica-rich liquids seems to exclude the direct melting of eclogite derived from mid-ocean-ridge basalt to produce alkaline lavas. Recycling oceanic crust in the source of alkaline magma requires either (1) that the mantle "digests" this component producing metasomatized CO2-rich peridotitic sources or (2) that low-degree melt from recycled oceanic crust reacts with peridotite in the presence of CO2, producing low-silica alkaline melt by olivine dissolution and orthopyroxene precipitation. These two hypotheses are plausible in terms of major elements. However, they have specific implications about the type and proportion of recycled lithologies present in the asthenosphere to explain the specific trace-element pattern of intraplate alkaline lavas. A third hypothesis for the formation of alkaline magmas is the melting of metasomatized lithosphere. In this model, the major- and trace-element signature of alkaline magma is not controlled by the asthenospheric source (i.e., the amount of oceanic crust or CO2 present in the asthenosphere), but by the petrological process that controls the percolation and differentiation of low-degree asthenospheric melts across the lithosphere. This process forms amphibole-bearing metasomatic veins that are a candidate source of alkaline rocks. This hypothesis offers an explanation for the generation of the Na-alkaline lavas with similar major- and trace-element composition that are observed worldwide and for the generation of K- and Na-alkaline magma observed in continental settings. This hypothesis requires the formation of significant amounts of metasomatic veins within the lithosphere. Qualitative analyses of the thermal implication of the potential models for the generation of alkaline rocks demonstrate that such magma requires low potential temperature (Tp: 1320 °C to 1350 °C). If temperatures are higher, melting of the convecting mantle will erase any signature of low-degree melts produced from fertile mantle lithologies. This analysis suggests that a role for hot thermal plumes in the generation of intraplate volcanoes dominated by alkaline magmas is unrealistic.
DS201701-0027
2016
Pilet, S.Pilet, S., Abe, N., Rochat, L., Kaczmarek, M-A., Hirano. N., Machida, S., Buchs, D.M., Baumgartner, P.O., Muntener, O.Pre-subduction metasomatic enrichment of the oceanic lithosphere induced by plate flexure.Nature Geoscience, Vol. 9, pp. 898-903.MantleSubduction

Abstract: Oceanic lithospheric mantle is generally interpreted as depleted mantle residue after mid-ocean ridge basalt extraction. Several models have suggested that metasomatic processes can refertilize portions of the lithospheric mantle before subduction. Here, we report mantle xenocrysts and xenoliths in petit-spot lavas that provide direct evidence that the lower oceanic lithosphere is affected by metasomatic processes. We find a chemical similarity between clinopyroxene observed in petit-spot mantle xenoliths and clinopyroxene from melt-metasomatized garnet or spinel peridotites, which are sampled by kimberlites and intracontinental basalts respectively. We suggest that extensional stresses in oceanic lithosphere, such as plate bending in front of subduction zones, allow low-degree melts from the seismic low-velocity zone to percolate, interact and weaken the oceanic lithospheric mantle. Thus, metasomatism is not limited to mantle upwelling zones such as mid-ocean ridges or mantle plumes, but could be initiated by tectonic processes. Since plate flexure is a global mechanism in subduction zones, a significant portion of oceanic lithospheric mantle is likely to be metasomatized. Recycling of metasomatic domains into the convecting mantle is fundamental to understanding the generation of small-scale mantle isotopic and volatile heterogeneities sampled by oceanic island and mid-ocean ridge basalts.
DS1982-0496
1982
Pilger, R.H.JR.Pilger, R.H.JR.The Origin of Hotspot Traces: Evidence from Eastern AustraliJournal of Geophysical Research, Vol. 87, No. B3, PP. 1825-1834.Australia, Eastern AustraliaGeochronology, Genesis
DS1997-0909
1997
Pili, E.Pili, E., Ricard, Y., Lardeaux, J.M.Lithospheric shear zones and mantle crust connectionsTectonophysics, Vol. 280, No. 1-2, Oct. 26, pp. 15-30.MantleLithosphere, Tectonics
DS202007-1162
2020
Pili, E.Martelat, J-E., Cardon, H., Lardeaux, J-M., Nicollet, C., Schulmann, K., Pili, E.Geophysical evidence for large scale mullion type structures at the mantle crust interface in southern Madagascar: implications for Neoproterozoic orogeny.International Journal of Earth Science, Vol. 109, 4, pp. 1487-1500.Africa, Madagascartectonics

Abstract: This study uses gravimetric data integrated with recent seismic data published on south Madagascar to investigate geometry of crust-mantle interface. The regional tectonic framework of Madagascar is characterised by anastomosing network of up to 15-km-wide, 600-km-long and north-oriented high-strain zones, which originated during Neoproterozoic convergence. The studied Bouguer anomalies obtained from the International Gravimetric Bureau were high-pass filtered to emphasise short-wavelength gravimetric variations (shorter than 200 km). The Pan-African high-strain zones coincide with the positive gravimetric anomalies suggesting a link with deep seated high-density material. Considering the present-day thickness of the crust (35 km) and its seismic velocity record, the gravimetric anomalies can be visualised as narrow vertical tabular bodies located at the base of the Moho. Modelling further confirmed that such narrow vertical bodies could be stable over geologic time scale since these structures are relatively small (10 to 30 km wide). The vertical tabular bodies possibly reflect material transfer such as vertical motion of sub-crustal weak and possibly partially molten mantle along vertical deformation zones. It is proposed that these structures were initiated by folding of weak mantle-crust interface characterised by low-viscosity contrast between weak mantle and stronger granulitized lower crust during bulk pure shear-dominated horizontal shortening. It is proposed that the cuspate-lobate "mullion-type" geometry mimics rheological inversions of mafic and felsic rocks and shape of folds of variable scale observed in southern Madagascar. The formation of such mega-mullion structures is possibly an expression of "crème brulée" rheological model, where the deformation of the lithosphere is governed by stronger granulitic lower crust and weaker partially molten and/or hydrated mantle.
DS200512-0859
2005
Pilidou, S.Pilidou, S., Priestly, K., Debayle, E., Gudmundson, O.Rayleigh wave tomography in the North Atlantic: high resolution images of the Iceland, Azores and Eifel mantle plumes.Lithos, Vol. 79, 3-4, pp. 453-474.Europe, IcelandTomography
DS200612-1110
2006
Pilidou, S.Priestley, K., Debayle, E., McKenzie, D., Pilidou, S.Upper mantle structure of eastern Asia from multimode surface waveform tomography.Journal of Geophysical Research, Vol. 111, B 10, B 10304.AsiaGeophysics - seismics
DS200512-0860
2004
Pilidou, SA.Pilidou, SA., Priestley, K., Gudmundsson, O., Debayle, E.Upper mantle S-wave speed heterogeneity and anisotropy beneath the North Atlantic from regional surface wave tomography: the Iceland and Azores plumes.Geophysical Journal International, Vol. 159, 3, pp. 1057-1076.Europe, IcelandGeophysics - seismics
DS1984-0709
1984
Pilipenko, A.P.Stogniy, G.A., Stogniy, V.V., Kelle, E.YA., Pilipenko, A.P.Atomic Chemistry Prospecting of Kimberlite Beds in Shield Regions.Razved. Okhr. Nedr., 1984, No. 4, PP. 24026.RussiaProspecting
DS1997-0910
1997
Pilipiuk, A.N.Pilipiuk, A.N., Ivanikov, V.V., Bulakh, A.B.Unusual mineral assemblages in carbonatites from a new occurrence in the Kola Karelia region, Russia.Geological Association of Canada (GAC) Abstracts, POSTER.Russia, Kola, KareliaCarbonatite
DS2001-0923
2001
Pilipiuk, A.N.Pilipiuk, A.N., Ivanikov, V.V., Bulakh, A.G.Unusual rocks and mineralization in a new carbonatite complex at Kandaguba Kola Peninsula, Russia.Lithos, Vol. 56, pp. 333-47.Russia, Kola PeninsulaChemistry - alkaline rocks, Kandaguba Complex
DS1999-0557
1999
Pilipjuk, A.N.Pilipjuk, A.N., Ivanikov, V.V., Rudashevsky, N.S.Minerals of rare earth elements (REE) and niobium in the late carbonatites of the Kandagubsky massif. RUSSProceedings Russ. Min. Soc. *RUSS, Vol. 128, 6, pp. 56-67.Russia, Kola PeninsulaCarbonatite
DS1989-0033
1989
Pilkington, M.Ardoh, A., Pilkington, M.Radon emanation studies of the Ile Bizard fault, MontrealGeoexploration, Vol. 25, pp. 341-354QuebecGeophysics, Radon
DS1989-1216
1989
Pilkington, M.Pilkington, M.Variable depth magnetization mapping: application To the Athabasca northern Alberta and SaskatchewanGeophysics, Vol. 54, No. 9, September pp. 1164-1173SaskatchewanGeophysics, Athabasca Basin
DS1989-1217
1989
Pilkington, M.Pilkington, M., Grieve, R.A.F., Gibb, R.A., Halpenny, J.F.Derived potential field dat a sets for North AmericaGeological Society of Canada (GSC) Forum 1989, P. 20 abstractGlobalMidcontinent, Geophysics
DS1990-0485
1990
Pilkington, M.Forsyth, D.A., Pilkington, M., Grieve, R.A.F., Abbinett, D.Major circular structure beneath southern Lake Huron defined from potential field dataGeology, Vol. 18, No. 8, August pp. 773-777Ontario, Great LakesGeophysics -aeromagnetics, Tectonics
DS1990-1184
1990
Pilkington, M.Pilkington, M.Lithospheric flexure and gravity anomalies at Proterozoic plate boundaries in the Canadian ShieldTectonophysics, Vol. 176, No. 3-4, May 10, pp. 277-290CanadaGeophysics -gravity, Tectonics-plate boundaries, Craton
DS1990-1185
1990
Pilkington, M.Pilkington, M., Keating, P.CONTAC and DYKE: two programs for the automatic interpretation of Magnetic and vertical gradient anomaliesGeological Survey of Canada Open File, No. 2267, 12p. report and 1 disk total cost $ 19.42GlobalGeophysics, Program - CONTAC DYKE.
DS1992-1194
1992
Pilkington, M.Pilkington, M., et al.Gravity anomaly map with shaded relief of gradient of North AmericaGeological Survey of Canada, Map 1807A 1: 10, 000, 000 $ 4.80Canada, United States, North AmericaMap -geophysics, Gravity Anomaly
DS1992-1195
1992
Pilkington, M.Pilkington, M., et al.Horizontal gradient of the Bouguer Gravity anomaly map of North AmericaGeological Survey of Canada, Map 1809A 1: 10, 000, 000 $ 4.80Canada, United States, North AmericaMap -geophysics, Gravity -Bouguer
DS1992-1196
1992
Pilkington, M.Pilkington, M., et al.Vertical gradient of the Bouger Gravity anomaly map of North AmericaGeological Survey of Canada, Map 1810A 1: 10, 000, 000 $ 4.80Canada, United States, North AmericaMap -geophysics, Gravity -Bouguer vertical gradient
DS1992-1197
1992
Pilkington, M.Pilkington, M., et al.Isostatic gravity anomaly map of North AmericaGeological Survey of Canada, Map 1808A 1: 10, 000, 000 $ 4.80Canada, United States, North AmericaMap -geophysics, Gravity -isostatic
DS1992-1198
1992
Pilkington, M.Pilkington, M., et al.Vertical gradient of the Bouguer Gravity anomaly map of North AmericaGeological Survey of Canada, Map 1810A 1: 10, 000, 000 $ 4.80Canada, United States, North AmericaMap, Gravity -Bouguer vertical gradient
DS1992-1199
1992
Pilkington, M.Pilkington, M., et al.Magnetic field intensity map of North AmericaGeological Survey of Canada, Map 1811A, 1: 10, 000, 000 $ 4.80Canada, United States, North AmericaMap, Magnetic field intensity
DS1992-1200
1992
Pilkington, M.Pilkington, M., Grieve, R.A.F.The geophysical signature of terrestrial impact cratersReviews of Geophysics, Vol. 30, No. 2, May pp. 161-181CanadaGeophysics -gravity, Impact craters
DS1992-1201
1992
Pilkington, M.Pilkington, M., Roest, W.Draping aeromagnetic dat a in areas of rugged topographyJournal of Applied Geophysics, Vol. 29, No. 2, August pp. 135-142CanadaGeophysics - aeromagnetics, Map
DS1993-1240
1993
Pilkington, M.Pilkington, M., Todoeschuck, J.P.Fractal magnetization of continental crustGeophysical Research Letters, Vol. 20, No. 7, April 9, pp. 627-630.MantleGeophysics
DS1994-1376
1994
Pilkington, M.Pilkington, M.Using fractal crustal magnetization models in magnetic interpretationGeophysical Prospecting, Vol. 42, No. 6, pp. 677-692GlobalGeophysics - magnetics, Fractal crustal
DS1995-1496
1995
Pilkington, M.Pilkington, M., Todeschuck, J.Magnetic field statistics: comparison of continental and oceanic crustEos, Vol. 76, No. 46, Nov. 7. p.F174. Abstract.Mantle, crustGeophysics -magnetics
DS1996-1117
1996
Pilkington, M.Pilkington, M., Roest, W.R.As assessment of long wave length magnetic anomalies over CanadaCanadian Journal of Earth Sciences, Vol. 33, No. 1, Jan. pp. 12-23.CanadaGeophysics -magnetics, Overview
DS1996-1118
1996
Pilkington, M.Pilkington, M., Roest, W.R.An assessment of long wavelength magnetic anomalies over CanadaCanadian Journal of Earth Sciences, Vol. 33, No. 1, Jan. pp. 12-23CanadaGeophysics, MAGSAT -overview
DS1997-0911
1997
Pilkington, M.Pilkington, M., Roest, W.R.Removing varying directional trends in aeromagnetic data: an example From the Slave Province.Geological Survey of Canada Forum 1997 abstracts, p. 14. AbstractNorthwest TerritoriesGeophysics - aeromagnetics
DS1998-1163
1998
Pilkington, M.Pilkington, M., Roest, W.R.Removing varying directional trends in aeromagnetic dataGeophysics, Vol. 63, No. 2, Mar-Apr, pp. 446-453.Northwest TerritoriesGeophysics - aeromagnetics, Mackenzie dyke swarm
DS1998-1164
1998
Pilkington, M.Pilkington, M., Roest, W.R.Removing varying directional trends in aeromagnetic dataGeophysics, Vol. 63, No. 2, Mar-Apr. pp. 446-53Northwest TerritoriesGeophysics - magnetics, Mackenzie dyke swarm
DS1999-0558
1999
Pilkington, M.Pilkington, M., Percival, J.A.Crustal magnetization and long wave aeromagnetic anomalies of the MintoBlock, Quebec.Journal of Geophysical Research, Vol. 104, No. 4, Apr. 10, pp. 7513-26.QuebecGeophysics - aeromagnetics, Minto Block - not specific to diamonds
DS2000-0751
2000
Pilkington, M.Pehrsson, S.J., Chacko, T., Pilkington, M., VilleneuveAnton terrane revisited: Late Archean exhumation of a moderate pressure granulite terrane in western SlaveGeology, Vol. 28, No. 12, Dec. pp. 1075-78.Northwest TerritoriesAnton terrane, Tectonic denudation
DS2000-0765
2000
Pilkington, M.Pilkington, M., Miles, W.F., Ross, G.M., Roest, W.R.Potential field signatures of buried Precambrian basement in the Western Canada sedimentary Basin.Canadian Journal of Earth Sciences, Vol.37, No.11, Nov.pp.1453-71.AlbertaTectonics - Precambrian, Geophysics - seismics
DS2001-0924
2001
Pilkington, M.Pilkington, M., Percival, J.A.Relating crustal magnetization and satellite altitude magnetic anomalies in the Ungava peninsula, north. Que.Earth and Planetary Science Letters, Vol. 194, No. 1-2, pp. 127-33.Quebec, Ungava, LabradorGeophysics - magnetics - not specific to diamonds
DS2001-0925
2001
Pilkington, M.Pilkington, M., Thomas, M.D.Magnetic gravity maps with interpretation of Precambrian basement of ManitobaGeological Survey of Canada (GSC) Open File, No. 3739, 4 maps 1:1,500,000 $ 104.ManitobaGeophysics - gravity
DS2002-0459
2002
Pilkington, M.Finn, C.A., Pilkington, M., Miles, Hernadez, Cuevas, Velez, Sweeney, KucksThe new North American magnetic anomaly mapGeological Society of America Annual Meeting Oct. 27-30, Abstract p. 387.United States, CanadaMap - magnetic
DS200612-1089
2006
Pilkington, M.Pilkington, M., Cowan, D.R.Model based separation filtering of magnetic data.Geophysics, Vol. 71, 2, L17-L23.AustraliaGeophysics - magnetics, kimberlites
DS200612-1090
2006
Pilkington, M.Pilkington, M., Snyder, D.B., Hemant, K.Weakly magnetic crust in the Canadian Cordillera.Earth and Planetary Science Letters, Vol. 248, 1-2, Aug. 15, pp. 461-470.Canada, British ColumbiaGeophysics - magnetics
DS201601-0045
2015
Pilkington, M.Snyder, D.B., Craven, J.A., Pilkington, M., Hillier, M.J.The three dimensional construction of the Rae craton, central Canada.Geochemistry, Geophysics, Geosystems: G3, Vol. 16, 10, pp. 3555-3574.Canada, Saskatchewan, AlbertaRae Craton

Abstract: Reconstruction of the 3-dimensional tectonic assembly of early continents, first as Archean cratons and then Proterozoic shields, remains poorly understood. In this paper, all readily available geophysical and geochemical data are assembled in a 3-D model with the most accurate bedrock geology in order to understand better the geometry of major structures within the Rae craton of central Canada. Analysis of geophysical observations of gravity and seismic wave speed variations revealed several lithospheric-scale discontinuities in physical properties. Where these discontinuities project upward to correlate with mapped upper crustal geological structures, the discontinuities can be interpreted as shear zones. Radiometric dating of xenoliths provides estimates of rock types and ages at depth beneath sparse kimberlite occurrences. These ages can also be correlated to surface rocks. The 3.6-2.6 Ga Rae craton comprises at least three smaller continental terranes, which "cratonized" during a granitic bloom. Cratonization probably represents final differentiation of early crust into a relatively homogeneous, uniformly thin (35-42 km), tonalite-trondhjemite-granodiorite crust with pyroxenite layers near the Moho. The peak thermotectonic event at 1.86-1.7 Ga was associated with the Hudsonian orogeny that assembled several cratons and lesser continental blocks into the Canadian Shield using a number of southeast-dipping megathrusts. This orogeny metasomatized, mineralized, and recrystallized mantle and lower crustal rocks, apparently making them more conductive by introducing or concentrating sulfides or graphite. Little evidence exists of thin slabs similar to modern oceanic lithosphere in this Precambrian construction history whereas underthrusting and wedging of continental lithosphere is inferred from multiple dipping discontinuities.
DS201809-2093
2018
Pilkington, M.Snyder, D.B., Schetselaar, E., Pilkington, M., Schaeffer, A.J.Resolution and uncertainty in lithospheric 3-D geological models. Canada MohoMineralogy and Petrology, doi.org/10.1007/ s00710-018-0619-2. 15p.MantleGeophysics

Abstract: As three-dimensional (3-D) modelling of the subcontinental mantle lithosphere is increasingly performed with ever more data and better methods, the robustness of such models is increasingly questioned. Resolution thresholds and uncertainty within deep multidisciplinary 3-D models based on geophysical observations exist at a minimum of three levels. Seismic waves and potential field measurements have inherent limitations in resolution related to their dominant wavelengths. Formal uncertainties can be assigned to grid-search type forward or inverse models of observable parameter sets. Both of these uncertainties are typically minor when compared to resolution limitations related to the density and shape of a specific observation array used in seismological or potential field surveys. Seismic wave source distribution additionally applies in seismology. A fourth, more complex level of uncertainty relates to joint inversions of multiple data sets. Using independent seismic wave phases or combining diverse methods provides another measure of uncertainty of particular physical properties. Extremely sparse xenolith suites provide the only direct correlation of rock type with observed or modelled physical properties at depths greater than a few kilometers. Here we present one case study of the Canadian Mohorovi?i? (Moho) discontinuity using only two data sets. Refracted and converted seismic waves form the primary determinations of the Moho depth, gravity field modeling provide a secondary constraint on lateral variations, the slope of the Moho, between the sparse seismic estimates. Although statistically marginal, the resulting co-kriged Moho surface correlates better with surface geology and is thus deemed superior.
DS2000-0292
2000
Pilkkington, M.Finn, C.A., Pilkkington, M., et al.Second year products of the North American magnetic anomaly database prograGeological Society of America (GSA) Abstracts, Vol. 32, No. 7, p.A-430.Canada, United States, CordilleraGeophysics - magnetics
DS202205-0704
2022
Pillay, D.Maritz, L., Pillay, D., Branch, G.M.The ecology of coastal wetland ponds created by diamond mining in southern Namibia. 1. Physical Conditions.African Journal of Marine Science, Vol. 44, 1, pp. 49-60.Africa, Namibiamining

Abstract: Coastal diamond mining in southern Namibia involves constructing seawalls to hold the sea at bay, and seaward accretion of the shoreline by up to 800 m opens what was previously the surf zone for excavation and extraction of bedrock alluvial diamonds. This has created large coastal wetland ponds of up to 380 000 m2 as the sea overtops the seawalls or seeps into the excavated areas. The ages of these ponds span 1-38 years. We investigated physical conditions in the ponds to determine whether they can function as saline wetlands equivalent to blind estuaries. Water temperatures were 6-10 °C higher than in the sea, as expected of shallow enclosed waterbodies. Dissolved oxygen was 82-137%, peaking at midday owing to photosynthesis, and the ponds were never hypoxic. Correlated with oxygen levels, pH values spanned 7.7-8.3, and always exceeded the pH of seawater. Chlorophyll a concentrations matched or exceeded the levels in seawater, reaching 76 µg l?1. The southern and central ponds had salinities close to those of seawater, but the salinity of northern ponds exceeded 80 after ?15 years, thus limiting their capacity to support wetland communities. Apart from this, these ponds are viable habitat that can support flora and fauna typical of saline wetlands, a habitat that is scarce along this arid coastline.
DS202205-0705
2022
Pillay, D.Maritz, L., Pillay, D., Branch, G.M.The ecology of coastal wetland ponds created by diamond mining in southern Namibia. 2. Saltmarsh vegetation.African Journal of Marine Science, Vol. 44, 1, pp. 61-68.Africa, Namibiamining

Abstract: Coastal diamond mining in southern Namibia involves constructing seawalls to hold the sea at bay, and seaward accretion of the shoreline by up to 800 m opens what was previously the surf zone for excavation and extraction of bedrock alluvial diamonds. This has created large coastal wetland ponds of up to 380 000 m2 as the sea overtops the seawalls or seeps into the excavated areas. The ages of these ponds span 1-38 years. We investigated physical conditions in the ponds to determine whether they can function as saline wetlands equivalent to blind estuaries. Water temperatures were 6-10 °C higher than in the sea, as expected of shallow enclosed waterbodies. Dissolved oxygen was 82-137%, peaking at midday owing to photosynthesis, and the ponds were never hypoxic. Correlated with oxygen levels, pH values spanned 7.7-8.3, and always exceeded the pH of seawater. Chlorophyll a concentrations matched or exceeded the levels in seawater, reaching 76 µg l?1. The southern and central ponds had salinities close to those of seawater, but the salinity of northern ponds exceeded 80 after ?15 years, thus limiting their capacity to support wetland communities. Apart from this, these ponds are viable habitat that can support flora and fauna typical of saline wetlands, a habitat that is scarce along this arid coastline.
DS200812-0924
2008
Pilldou, S.Priestly, K., McKenzie, D., Debayle,E., Pilldou, S.The African upper mantle and its relationship to tectonics and surface geology.Geophysical Journal International, Vol. 175, 3, pp. 1108-1125.AfricaTectonics
DS1989-1023
1989
Pillenger, C.T.Milledge, H.J., Mendelssohn, J.J., Boyd, S.R., Pillenger, C.T.Infrared topography and carbon and nitrogen isotope distribution in natural and synthetic diamonds in relation to mantle processesDiamond Workshop, International Geological Congress, July 15-16th. editors, pp. 55-60. AbstractGlobalMantle, Diamond morphology, natur
DS1992-1315
1992
Pillenger, C.T.Russell, S.S., Pillenger, C.T., Arden, J.W., Lee, M.R.A new type of meteoritic diamond in the enstatite chondrite AbeeScience, Vol. 256, No. 5054, April 10, pp. 206-209GlobalMeteorites, Diamond
DS1983-0477
1983
Piller, R.C.Nelson, R., Hudson, J.A., Mazey, D.J., Piller, R.C.Diamond Synthesis; Internal Growth During Carbon Ion ImplantationRoyal Soc. London Proceedings, Series A., Vol. 386, No. 1790, PP. 211-222.GlobalSynthesis
DS1989-1218
1989
Pillet, D.Pillet, D., Bonhomme, M.G., Duthou, ChenevoyChronologie Rb-Sr et K-Ar du granite peralcalin du Lac Brisson, Labradorcentral.Canadian Journal of Earth Sciences, Vol. 26, pp. 328-32.Labrador, QuebecGeochronology
DS1987-0197
1987
Pillindesly, C.T.Exley, R.A., Boyd, S.R., Mattey, D.P., Pillindesly, C.T.Nitrogen isotope geochemistry of basaltic glasses- implications for mantle degasing and structureEarth and Planetary Sci. Letters, Vol. 81, No. 2-3, January pp. 163-174GlobalMantle genesis
DS1992-0155
1992
Pillinge, C.ET.Boyd, S.R., Pillinge, C.ET., Milledge, H.J., Seal, M.J.C-isotopic and N-isotopic composition and the infrared absorption spectraof coated diamonds-evidence regional uniformity of CO2-H2) rich fluids lithospheric mantleEarth and Planetary Science Letters, Vol. 108, No. 1-3, January pp. 139-150MantleCoated diamonds, Geochronology
DS1995-1694
1995
PillingerSehlkov, D., Verchovsky, A.B., Milledge, H.J., PillingerCarbonado: a comparison between Brazilian and Ubangui sources based on carbon and nitrogen isotopes.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 518-520.Brazil, Central African RepublicCarbonado, Geochronology
DS2001-0319
2001
PillingerFisenko, A.V., Verhovsky, Semenova, Ivanov, PillingerThe Kaidun meteorite: interstellar diamond in the chromium and Ci carbonaceous components.Geochemistry International, Vol. 38, Suppl. 3, pp. S294-301.GlobalMeteorite, Diamond - mineralogy
DS2002-0461
2002
PillingerFisenko, A.V., Verchovsky, Semenova, PillingerInterstellar diamond in the Efremovka CV3 chondrite: pyrolysis of different size fractions of grains.Geochemistry International, Vol.40,3,pp.209-28.GlobalMetorite - diamond
DS1983-0592
1983
Pillinger, C.T.Swart, P.K., Pillinger, C.T.Carbon Isotopic Variation With Individual DiamondsNature., Vol. 303, No. 5920, JUNE 30TH. PP. 793-794.GlobalMorphology, Crystallography
DS1985-0509
1985
Pillinger, C.T.Ozima, M., Zashu, S., Mattey, D.P., Pillinger, C.T.Helium, argon and carbon isotopic compositions in diamonds and theirapplications in mantle evolution.*JAPGeochem. Journal, *JAP, Vol. 19, No. 3, pp. 127-134GlobalDiamond Morphology
DS1985-0510
1985
Pillinger, C.T.Ozima, M., Zashu, S., Mattey, D.P., Pillinger, C.T.Helium, Argon and Carbon Isotopic Compositions in Diamonds And Their Implications in Mantle Evolution.Geochemical Journal, Vol. 19, No. 3, PP. 127-134.GlobalGeochronology, Diamond Morphology
DS1986-0536
1986
Pillinger, C.T.Mattey, D., Pillinger, C.T., Menzies, M.A.Abundances and carbon isotope compositions of trapped fluids in mantlediopsides: implications for mantle recycyling modelsProceedings of the Fourth International Kimberlite Conference, Held Perth, Australia, No. 16, pp. 276-278GlobalBlank
DS1987-0076
1987
Pillinger, C.T.Boyd, S.R., Mattey, D.P., Pillinger, C.T., Milledge, H.J.Multiple growth events during diamond genesis: an integrated study of carbon and nitrogen isotopes and nitrogen aggregation state in coated stonesEarth and Planetary Science Letters, Vol. 86, pp. 341-353Democratic Republic of CongoMbuji Mayi
DS1987-0447
1987
Pillinger, C.T.Mattey, D.P., Exley, R.A., Boyd, S.R., Pillinger, C.T., MenziesCarbon isotopes in oceanic and continental lithosphereTerra Cognita, Conference abstracts Oceanic and Continental Lithosphere:, Vol. 7, No. 4, Autumn, abstract only p. 618GlobalBlank
DS1988-0080
1988
Pillinger, C.T.Boyd, S.R., Pillinger, C.T., Milledge, H.J., Mendelsson, M.J.Fractionation of nitrogen isotopes in a synthetic diamond of mixed crystal habitNature, Vol. 331, No. 6157, Feb. 18, pp. 604-607GlobalBlank
DS1989-0959
1989
Pillinger, C.T.Mattey, D.P., Exley, R.A., Pillinger, C.T., Menzies, M.A., PorcelliRelationships between Carbon, Heleum, Strontium and neodymium isotopes in mantle diopsidesGeological Society of Australia Inc. Blackwell Scientific Publishing, No. 14, Vol. 2, pp. 913-921GlobalMantle xenoliths
DS1994-0202
1994
Pillinger, C.T.Boyd, S.R., Pillinger, C.T.A preliminary study of 15N/14N in octahedral growth form diamondsChemical Geology, Vol. 116, No. 1-2, Sept. 1, pp. 43-60.GlobalDiamond morphology, Diamond -nitrogen
DS1994-1525
1994
Pillinger, C.T.Sano, Y., Nagao, K., Pillinger, C.T.Carbon and noble gases in Archean chertChemical Geology, Vol. 112, No. 3-4, February 10, pp. 327-342GlobalChert, Geochemistry
DS1995-0823
1995
Pillinger, C.T.Hough, R.M., Gilmour, I., Pillinger, C.T., Arden, H.J.Diamond and silicon carbide in impact melt rock from the Ries impactcrater.Nature, Vol. 378, No. 6552, Nov. 2, pp. 41-44.GlobalDiamond, SIC., Deposit -Ries crater
DS1995-1252
1995
Pillinger, C.T.Milledge, H.J., Shelkov, D., Pillinger, C.T., VerchovskyProblems associated with the existence of carbonadoProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 387-388.GlobalCarbonado, Morphology
DS1995-1962
1995
Pillinger, C.T.Van Heerden, L.A., Boyd, S.R., Pillinger, C.T.The carbon and nitrogen isotope characteristics of Argyle and Ellendalediamonds.Proceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 225-227.AustraliaGeochronology, Deposit -Argyle, Ellendale
DS1995-1963
1995
Pillinger, C.T.Van Heerden, L.A., Boyd, S.R., Pillinger, C.T.The carbon and nitrogen isotope characteristics of the Argyle and Ellendalediamonds, Western Australia.International Geology Review, Vol. 37, No. 1, Jan. pp. 39-50.AustraliaGeochronology, Deposit -Argyle, Ellendale
DS1995-1964
1995
Pillinger, C.T.Van Heerden, L.A., Boyd, S.R., Pillinger, C.T., MilledgeThe fractionation of nitrogen and carbon isotope ratios in Western Australian diamonds.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 228-230.AustraliaGeochronology, Deposit -Argyle, Ellendale
DS1997-0523
1997
Pillinger, C.T.Hough, R.M., Gilmour, I., Pillinger, C.T., LangenhorstDiamonds from the iridium rich K-T boundary layer at Arroyo el Mimbral, Tamaulipas, Mexico.Geology, Vol. 25, No. 11, Nov. pp. 1019-22.MexicoK-T boundary, Diamonds - mineralogy, techniques
DS1997-1206
1997
Pillinger, C.T.Verkhovsky, A.B., Milledge, H.J., Pillinger, C.T.Carbonado: a comparison between Brazilian and Ubangui sources with other forms of microcrystalline diamond..Russian Geology and Geophysics, Vol. 38, No. 2, pp. 332-340.Brazil, Central African RepublicGeochronology, carbon and nitrogen isotope, Carbonado
DS1998-1331
1998
Pillinger, C.T.Shelkov, D.A., Verchovsky, A.B., Pillinger, C.T.The radial distribution of implanted and trapped 4He in single diamond crystals and implications for carbonadoChemical Geology, Vol. 149, No. 1-2, July 10, pp. 109-116.GlobalCarbonado, Diamond morphology
DS1992-1202
1992
Pilon, J.A.Pilon, J.A.Ground penetrating radarGeological Survey of Canada, Paper 90-4, 160p. approx. $ 20.00CanadaRadar, geophysics, Mining applications
DS2002-1265
2002
Pilot, S.Pilot, S., Hernadez, J., Villemant, B.Evidence for high silicic melt circulation and metasomatic events in the mantle beneath alkaline provinces: the Na Fe augitic green core pyroxenes...Mineralogy and Petrology, Vol. 76, No. 1-2, pp. 39-62.French Massif CentralTertiary alkali basalts - Cantal Massif
DS1993-0340
1993
Pilote, P.Desrochers, J-P., Hubert, C., Ludden, J.N., Pilote, P.Accretion of Archean oceanic plateau fragments in the Abitibi greenstonebelt, CanadaGeology, Vol. 21, No. 5, May pp. 451-454QuebecArc-arc collision model, Malartic block
DS1997-0912
1997
Pilote, P.Pilote, P., Dion, C., Joanisse, David, Machado, KirkhaM.Geochronologie des mineralisations d'affiliation magmatique de l'Abitibi -implications geotectoniques.Quebec Department of Mines, DV97-03, p. 47.QuebecGeochronology, Magmatism - not specifc to diamonds
DS201809-2102
2018
Piltz, R.Thomson, A.R., Dobsdon, D.P., Brodhollt, J., Crichton, W., Cerantola, V., Piltz, R.Crystallographic in corporation of hydrogen in ringwoodite.Goldschmidt Conference, 1p. AbstractMantlewater

Abstract: The transition zone (TZ) is believed to be the primary destination of subducted water [1], with the main TZ minerals (wadsleyite and ringwoodite) capable of holding up to ~ 3 wt.% H2O in their structures’. Observations of high attenuation and elevated conductivity suggest some areas of the transition zone are hydrated [2,3]. Combined with the observation of ~ 1.4 wt% H2O in a diamond-hosted ringwoodite inclusion [4], it is probable that the transition zone is at least regionally, if not globally, “wet”. The presence of water can induce partial melting, alter chemical partitioning and drastically change the strength of rocks. The detailed effect of water’s presence in the TZ will strongly depend on hydrogen’s incorporation mechanism, i.e. exchange with Si4+, Mg2+, Fe2+ cations or coupled substitution with Fe3+ in ringwoodite. Recent developments in neutron single-crystal Laue diffraction now allow measurements on crystals smaller than 0.1 mm3 [5]. Here we quantitatively study the incorporation of hydrogen in a synthetic iron-bearing ringwoodite. A multi-technique approach, with independent determination of chemistry, ferric iron content, water content and structure via x-ray and neutron diffraction allows a detailed study of the hydrous ringwoodite structure and the incorporation mechanism of water throughout Earth’s TZ.
DS201112-0734
2010
Pimenta, M.A.Newman, J.A., Teixeira Carvalho de Newman, D., Gandini, A.L., Souza Gomes, N., Krambrock, K.W.H., Pimenta, M.A.Caracterizacao mineralogica dos diamantes policristalinos (carbonados) da regiao de Santa Elena de Uairen, estado Bolivar, Venezuela.5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 46-47.South America, VenezuelaCarbonado
DS201709-2043
2017
Pimenta Martins, L.G.Pimenta Martins, L.G., Matos, M.J.S., Paschoal, A.R., Freire, P.T.C., Andrade, N.F., Aguiar, A.L., Kong, J., Neves, B.R.A., de Oliveira, A.B., Mazzoni, M.S.C., Souza Filhio, A.G., Cancad, L.G.Raman evidence for pressure induced formation of diamondene.Nature Communications, Vol. 8, 9p.Technologydiamondene

Abstract: Despite the advanced stage of diamond thin-film technology, with applications ranging from superconductivity to biosensing, the realization of a stable and atomically thick two-dimensional diamond material, named here as diamondene, is still forthcoming. Adding to the outstanding properties of its bulk and thin-film counterparts, diamondene is predicted to be a ferromagnetic semiconductor with spin polarized bands. Here, we provide spectroscopic evidence for the formation of diamondene by performing Raman spectroscopy of double-layer graphene under high pressure. The results are explained in terms of a breakdown in the Kohn anomaly associated with the finite size of the remaining graphene sites surrounded by the diamondene matrix. Ab initio calculations and molecular dynamics simulations are employed to clarify the mechanism of diamondene formation, which requires two or more layers of graphene subjected to high pressures in the presence of specific chemical groups such as hydroxyl groups or hydrogens.
DS2002-1681
2002
PimentelWalker, R.J., Prichard. H.M., Ishiwatari, A., PimentelThe osmium isotopic composition of convecting upper mantle deduced from ophiolite chromites.Geochimica et Cosmochimica Acta, Vol. 66, No. 2, pp. 329-45.MantleGeochronology, Chromites
DS200712-0144
2007
PimentelCarlson, R.W., Aruajo, Junqueira-Brod, Gaspar, Brod, Petrinovic, Hollanda, Pimentel, SichelChemical and isotopic relationships between peridotite xenoliths and mafic-ultrapotassic rocks from southern Brazil.Chemical Geology, Vol. 242, 3-4, pp. 418-437.South America, BrazilGeochemistry
DS200712-0145
2007
PimentelCarlson, R.W., Aruajo, Junqueira-Brod, Gaspar, Brod, Petrinovic, Hollanda, Pimentel, SichelChemical and isotopic relationships between peridotite xenoliths and mafic-ultrapotassic rocks from southern Brazil.Chemical Geology, Vol. 242, 3-4, pp. 418-437.South America, BrazilGeochemistry
DS1998-0128
1998
Pimentel, M.Bizzi, L.A., Pimentel, M.Source characteristics of Brazilian kimberlites7th International Kimberlite Conference Abstract, pp. 87-88.BrazilGeochronology, Deposit - Paranatinga, Batovi, Jaibaras, Moana Tinguins
DS1992-1203
1992
Pimentel, M.M.Pimentel, M.M., Fuck, R.A.Neoproterozoic crustal accretion in central BrasilGeology, Vol. 20, No. 4, April pp. 375-379BrazilGeochronology, Craton
DS1996-1119
1996
Pimentel, M.M.Pimentel, M.M., Fuck, R.A., De Alvararenga, J.S.Post Brasiliano (Pan African) high K granitic magmatism in Central Brasil:the role of Late Precambrian.....Prcambrian Research, Vol. 80, pp. 217-238BrazilOrogeny, Extension related Late Precambrian -early Paleozoic
DS1997-0235
1997
Pimentel, M.M.Da Silva Filho, A.F., Guimaraes, I.P., Pimentel, M.M.Geochemical signatures of main Neoproterozoic late tectonic granitoids from Proterozoic Sergipano beltInternational Geol. Rev, Vol. 39, No. 7, July, pp. 639-659BrazilGeochemistry - Sergipano, Brasiliano Orogeny
DS1997-0913
1997
Pimentel, M.M.Pimentel, M.M., Whitehouse, M.J., Machado, N.The Mara Rosa Arc in the To cantins Province: further evidence for Neoproterozoic crustal accretion ..Precambrian Research, Vol. 81. No. 3-4, Feb. 1, pp. 299-Brazil, CentralTectonics, Proterozoic
DS2000-0403
2000
Pimentel, M.M.Heilbron, M., Brito Neves, B.B., Pimentel, M.M., et al.Neoproterozoic orogenic systems in eastern, central and northeastern Brasil,and evolution of Gondwana.Igc 30th. Brasil, Aug. abstract only 1p.Brazil, West AfricaTectonics - Craton, orogeny
DS2002-1209
2002
Pimentel, M.M.Pandit, M.K., Sial, A.N., Sukumaran, G.B., Pimentel, M.M., Ramasamy, A.K.Depleted and enriched mantle sources for Paleo- and Neoproterozoic carbonatites ofChemical Geology, Vol. 189,1-2,pp. 69-89.India, Tamil NaduCarbonatite - geochronology, Deposit - Samalpatti, Sevattur, Mulakkasu
DS2003-0288
2003
Pimentel, M.M.Costa, V.S., Gaspar, J.C., Pimentel, M.M.Peridotite and eclogite xenoliths from the Juin a kimberlite province, Brazil8 Ikc Www.venuewest.com/8ikc/program.htm, Session 6, POSTER abstractBrazilBlank
DS2003-0865
2003
Pimentel, M.M.Maiade Hollanda, M.H., Pimentel, M.M., Jardim de Sa, E.F.Paleoproterozoic subduction related metasomatic signatures in the lithospheric mantleJournal of South American Earth Sciences, Vol. 15, 8, pp. 885-900.Brazil, southeastSubduction, Alkaline rocks
DS2003-1077
2003
Pimentel, M.M.Pimentel, M.M., Dantas, E.L., Fuck, R.A., Armstrong, R.A.Shrimp and conventional U Pb age, Sm Nd isotopic characteristics and tectonicAnais Academia Brasileira de Ciencias, Vol. 75, 1, pp. 97-108.Brazil, GoiasGeochronology, Alkaline rocks
DS2003-1081
2003
Pimentel, M.M.Piuzana, D., Pimentel, M.M., Fuck, R.A., Armstrong, R.SHRIMP U Pb and Sm Nd dat a for the Araxa group and associated magmatic rocks:Precambrian Research, Vol. 125, 1-2, pp. 139-60.BrazilMagmatism - Carbonatite
DS200412-0375
2003
Pimentel, M.M.Costa, V.S., Gaspar, J.C., Pimentel, M.M.Peridotite and eclogite xenoliths from the Juin a kimberlite province, Brazil.8 IKC Program, Session 6, POSTER abstractSouth America, BrazilMantle petrology
DS200412-0394
2004
Pimentel, M.M.Da Silva Schmitt, R., Trouw, R.A.J., Van Schmus, W.R., Pimentel, M.M.Late amalgamation in the central part of West Gondwana: new geochronological dat a and the characterization of a Cambrian collisiPrecambrian Research, Vol. 133, 1-2, August 5, pp. 29-61.South America, BrazilGeochronology, metamorphism
DS200412-1204
2003
Pimentel, M.M.Maiade Hollanda, M.H., Pimentel, M.M., Jardim de Sa, E.F.Paleoproterozoic subduction related metasomatic signatures in the lithospheric mantle beneath NE Brazil: inferences from trace eJournal of South American Earth Sciences, Vol. 15, 8,pp. 885-900.South America, BrazilSubduction Alkaline rocks
DS200412-1548
2003
Pimentel, M.M.Pimentel, M.M., Dantas, E.L., Fuck, R.A., Armstrong, R.A.Shrimp and conventional U Pb age, Sm Nd isotopic characteristics and tectonic significance of the K rich Itapuranga Suite in GoiAnais Academia Brasileira de Ciencias, Vol. 75, 1, pp. 97-108.South America, Brazil, GoiasGeochronology Alkaline rocks
DS200412-1554
2003
Pimentel, M.M.Piuzana, D., Pimentel, M.M., Fuck, R.A., Armstrong, R.SHRIMP U Pb and Sm Nd dat a for the Araxa group and associated magmatic rocks: constraints for the age of sedimentation and geodyPrecambrian Research, Vol. 125, 1-2, pp. 139-60.South America, Brazil, BahiaGeochronology Magmatism - carbonatites
DS200512-0442
2005
Pimentel, M.M.Hollanda, M.H.B.M., Pimentel, M.M., Oliveira, D.C., De Sa, E.F.J.Lithosphere - asthenosphere interaction and the origin of Cretaceous tholeiitic magmatism in northeastern Brazil: Sr Nd Pb isotopic evidence.Lithos, Advanced in press,South America, BrazilRio Ceara Mirim dike, magmatism
DS201112-0419
2010
Pimentel, M.M.Hauser, N., Matteini, M., Omarini, R.H., Pimentel, M.M.Constraints on metasomatized mantle under central South America: evidence from Jurassic alkaline lamprophyre dykes from the eastern Cordillera, NM Argentina.Mineralogy and Petrology, Vol. 100, pp. 153-184.South America, ArgentinaLamprophyre
DS201312-0228
2013
Pimentel, M.M.Dristas, J.A., Martinez, J-C., Massone, H-J., Pimentel, M.M.Mineralogical and geochemical characterization of a rare ultramafic lamprophyre in the Tandilia belt basement, Rio de la Plata, Argentina.Journal of South American Earth Sciences, Vol. 43, pp. 46-61.South America, ArgentinaLamprophyre
DS201607-1316
2016
Pimentel, M.M.Srivastava, R.K., Pimentel, M.M., Gautam, G.C.Nd-isotope and geochemistry of an early Paleoproterozoic high Si high Mg boninite-norite suite of rocks in the southern Bastar craton, central India: petrogenesis and tectonic significance.International Geology Review, Vol. 58, 13, pp. 1596-1615.IndiaBoninites

Abstract: Nd-isotope and lithogeochemistry of an early Palaeoproterozoic high-Si high-Mg boninite -norite (BN) suite of rocks from the southern Bastar craton, central India, are presented to understand their nature, origin, and tectonic setting of emplacement. Various types of evidence, such as field relationships, radiometric metamorphic ages, and the global distribution of BN magmatism, suggest emplacement in an intracratonic rift setting, commonly around 2.4 -2.5 Ga. On the basis of geochemistry these high-Si high-Mg rocks are classified as high-Ca boninites, high-Mg norites, and high-Mg diorites. Nd-isotope data indicate that the high-Mg norite and the high-Mg diorite samples are similar, whereas the high-Ca boninites have a different isotopic character. The high-Mg norite and the high-Mg diorite samples have younger TDM model ages than the high-Ca boninites. Geochemical and Nd-isotopic characteristics of the studied rocks indicate some prospect of crustal contamination; however, the possibility of mantle metasomatism during ancient subduction event cannot be ignored. Trace-element modelling suggests that the high-Ca boninites may have crystallized from a magma generated by a comparatively greater percentage of melting of a lherzolite mantle source than the source for the other two varieties. Furthermore, the high-Ca boninite rocks are most likely derived from an Archaean subduction process (the Whundo-type), whereas the other two types are the products of the interaction of subduction-modified refractory mantle wedge and a plume, around the Neoarchaean -Palaeoproterozoic boundary. The emplacement of the high-Mg norites and the high-Mg diorites may be linked to crustal thickening and associated cratonization at the end of the Archaean.
DS1970-0383
1971
Pimentel, N.R.Pimentel, N.R.Potassium Argon Age Determination of a Mica Peridotite Dikein Western Penn
 
 

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