Kaiser Bottom Fish OnlineFree trialNew StuffHow It WorksContact UsTerms of UseHome
Specializing in Canadian Stocks
SearchAdvanced Search
Welcome Guest User   (more...)
Home / Education
Education
 

SDLRC - Scientific Articles all years by Author - De-Dn


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 - De-Dn
Posted/
Published
AuthorTitleSourceRegionKeywords
DS1994-1164
1994
de, R.J.Meijer, de, R.J., Tanczos, I.C., Stapel, C.Radiometric techniques in heavy mineral exploration and exploitationExploration and Mining Geology, Vol. 3, No. 4, Oct. pp. 389-98GlobalHeavy sands, Radiometric mapping
DS1998-0332
1998
De, S.De, S., Heaney, P.J., Vincenzi, E.P., Hargraves, R.B.Microstructural comparison between natural polycrystalline diamond -carbonado and artificial..Ima 17th. Abstract Vol., p. A16. poster abstractBrazil, Central African RepublicCarbonado, Diamond synthesis
DS2001-0239
2001
De, S.De, S., Heaney, P.J., Wang, J.Chemical heterogeneity in carbonado, an enigmatic polycrystalline diamondEarth and Plan. Sci. Letters, Vol. 185, No. 3-4, Feb. 28, pp. 315-30.Central African RepublicGeochemistry - carbonado, Cathodluminescence
DS200412-0433
2004
De, S.De, S., Heaney, P.J., Fei, Y., Vicenzi, E.P.Microstructural study of synthetic sintered diamond and comparsion with carbonado, a natural polycrstalline diamond.American Mineralogist, Vol. 89, 2-3, Feb. Mar. pp. 439-46.TechnologyDiamond morphology
DS200512-0412
2005
De, S.Heaney, P.J., Vicenzi, E.P., De, S.Strange diamonds: the mysterious origins of carbonado and framesite.Elements, Vol. 1, 2, March pp. 85-90.South America, Brazilframesite, polycrystalline, mineralogy
DS200812-0773
2008
De, S.Mukhopadhyay, R., Rajesh, M., De, S., Chakraborty, B., Jauhan, P.Structural highs on the western continental slope of India: implications for regional tectonics.Geomorphology, Vol. 96, 1-2, pp. 48-61.IndiaTectonics
DS2000-0150
2000
De, S.K.Chacko, T., De, S.K., Creaser, R.A., Muehlenbachs, K.Tectonic setting of the Taltson magmatic zone at 1.9 - 2.0 Ga: a granitoid based perspective.Canadian Journal of Earth Sciences, Vol.37, No.11, Nov.pp.1597-09.Alberta, Northwest TerritoriesTectonics, Geochronology
DS2000-0222
2000
De, S.K.De, S.K., Chacko, T., Creaser, R.A., Muelenbachs, K.Geochemical and neodymium lead O isotope systematics of granites from the Taltson magmatic zone Implications for ...Precambrian Research, Vol. 102, No. 3-4, Aug. pp. 221-50.AlbertaTectonics - Proterozoic - western Laurentia, Geochronology
DS200612-1145
2001
De, S.K.Reddy, R.A., Murty, N.S., De, S.K.Target areas for kimberlite exploration from potential field dat a using geographic information system, Narayanpet kimberlite field, Andhra Pradesh.National Seminar on Exploration Survey, Geological Society of India Special Publication, No. 58, pp. 417-425.India, Andhra PradeshDiamond exploration - geophysics
DS1984-0451
1984
De abreu, F.A.M.Lesquer, A., Beltrao, J.F., De abreu, F.A.M.Proterozoic Links between Northeastern Brasil and West Africa: a Plate Tectonic Model Based on Gravity Data.Tectonophysics, Vol. 110, PP. 9-26.Brazil, South AfricaTectonics
DS200612-0738
2005
De Albuquerque, C.A.R.Kotschoubey, B., Hieronymus, B., De Albuquerque, C.A.R.Disrupted peridotites and basalts from the Neoproterozoic Araguaia belt, (northern Brazil): remnants of a poorly evolved oceanic crust?Journal of South American Earth Sciences, Vol. 20, 3, Dec. pp. 211-230.South America, BrazilMetamorphism - Tocantins Group
DS1993-0332
1993
De Albuquerque Scarbi, P.B.De Albuquerque Scarbi, P.B., Gomez Valenca, J.Kasilite in Brazilian kamafugitic rocksMineralogical Magazine, Vol. 57, No. 386, March pp. 165-171BrazilUltramafic, Mineralogy
DS200912-0687
2009
De Albuquerque Sgarbi, P.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
DS201901-0022
2018
de Alkmim, F.F.Cordani, U.G., Ernesto, M., Da Silva Dias, M.A.F., de Alkmim, F.F., Medonca, C.A., Albrecht, R.Un pouco de historia: as Ciencias da Terra no Brasil colonial e no Imperio. ( IN PORT) History of Brazil gold and diamondsEstudos Avancados ( Ensino de Geosciencias na universidade), Vol. 32, (94), pp. 309-330. pdf available in PORT.South America, Brazilhistory
DS201911-2518
2019
de Almeida, D.D.P.M.de Almeida Morales, B.A., de Almeida, D.D.P.M., Koester, E., da Rocha, A.M.R., Dorneles, N.T., da Rosa, M.B., Martins, A.A.Mineralogy, whole-rock geochemistry and C, O isotopes from Passo Feio carbonatite, Sul-Riograndense shield, Brazil.Journal of South American Earth Sciences, Vol. 94, 102208 13p. PdfSouth America, Brazilcarbonatite

Abstract: Carbonatites are peculiar igneous rocks, consisting mainly of greater than 50% carbonate minerals, which arouse an economic interest due to the potentiality of high phosphate content and Light Rare Earth Elements (LREE) associated with their occurrence. The Passo Feio Carbonatite (PFC) is located 17?km Southwest of Caçapava do Sul city and constitutes NW dipping body, which is interposed with Passo Feio Formation metamorphic rocks. The PFC varies texturally from massive to foliated, being mainly composed of calcites and dolomites and on a smaller scale by apatites, phlogopites and tremolites. The opaque minerals correspond to hematites, magnetites, pyrites and barites, while the accessory minerals are represented by zircons, monazites- (Ce) and aeschynites- (Ce). Probably those REE mineral phases correspond to a hydrothermal stage, with the REE remobilization from apatites into those latter REE-rich mineral phases - this hypothesis is corroborated by geochemistry, mineral chemistry and microtextures found. Considering the results of mineral chemistry and taking into account the textural criteria, it was possible to classify carbonatite as an alvikite, with geochemical patterns that do not indicate economic potential for REE. However, soil geochemistry showed an important enrichment in REE, reflecting a probable concentration of monazites- (Ce) and aeschynites- (Ce), and because of this, it was possible to establish a zone in which the Passo Feio Carbonatite would probably be extended. In the stable isotope analyzes, the d13C values varied between -4.14 and -3.89‰ while those of d18O between 10.01 and 11.32‰ which can be attributed to the cooling of the magma itself, without suggesting metamorphic processes or subsequent changes. The deformation found in this carbonatite was probably developed in late-magmatic conditions, guided by tectonics associated with horizontal movements in shear zones. Thus, this work suggests that this carbonatite was the product of the reactivation of mantle sources, within a post-collision magmatic context of the Sul-Riograndense Shield.
DS1985-0272
1985
De almeida, F.F.M.Hasui, Y., De almeida, F.F.M.The Central Brasil Shield ReviewedEpisodes, Vol. 8, No. 1, MARCH PP. 29-37.BrazilTectonics
DS1998-0166
1998
De Almeida, F.F.M.Brito Neves, B.B.D., De Almeida, F.F.M., Carneiro, C.D.Origin and evolution of the South American PlatformJournal of African Earth Sciences, Vol. 27, 1A, p. 37. AbstractBrazilGondwana, Tectonics
DS2000-0211
2000
De Almeida, F.F.M.De Almeida, F.F.M., De Brito Neves, B.B., CarneiroThe origin and evolution of the South American PlatformEarth Science Reviews, Vol. 14, pp. 77-111.South America, Brazil, BoliviaTectonics - shield, Craton, platform, Proterozoic, Archean Phanerozoic
DS201911-2518
2019
de Almeida Morales, B.A.de Almeida Morales, B.A., de Almeida, D.D.P.M., Koester, E., da Rocha, A.M.R., Dorneles, N.T., da Rosa, M.B., Martins, A.A.Mineralogy, whole-rock geochemistry and C, O isotopes from Passo Feio carbonatite, Sul-Riograndense shield, Brazil.Journal of South American Earth Sciences, Vol. 94, 102208 13p. PdfSouth America, Brazilcarbonatite

Abstract: Carbonatites are peculiar igneous rocks, consisting mainly of greater than 50% carbonate minerals, which arouse an economic interest due to the potentiality of high phosphate content and Light Rare Earth Elements (LREE) associated with their occurrence. The Passo Feio Carbonatite (PFC) is located 17?km Southwest of Caçapava do Sul city and constitutes NW dipping body, which is interposed with Passo Feio Formation metamorphic rocks. The PFC varies texturally from massive to foliated, being mainly composed of calcites and dolomites and on a smaller scale by apatites, phlogopites and tremolites. The opaque minerals correspond to hematites, magnetites, pyrites and barites, while the accessory minerals are represented by zircons, monazites- (Ce) and aeschynites- (Ce). Probably those REE mineral phases correspond to a hydrothermal stage, with the REE remobilization from apatites into those latter REE-rich mineral phases - this hypothesis is corroborated by geochemistry, mineral chemistry and microtextures found. Considering the results of mineral chemistry and taking into account the textural criteria, it was possible to classify carbonatite as an alvikite, with geochemical patterns that do not indicate economic potential for REE. However, soil geochemistry showed an important enrichment in REE, reflecting a probable concentration of monazites- (Ce) and aeschynites- (Ce), and because of this, it was possible to establish a zone in which the Passo Feio Carbonatite would probably be extended. In the stable isotope analyzes, the d13C values varied between -4.14 and -3.89‰ while those of d18O between 10.01 and 11.32‰ which can be attributed to the cooling of the magma itself, without suggesting metamorphic processes or subsequent changes. The deformation found in this carbonatite was probably developed in late-magmatic conditions, guided by tectonics associated with horizontal movements in shear zones. Thus, this work suggests that this carbonatite was the product of the reactivation of mantle sources, within a post-collision magmatic context of the Sul-Riograndense Shield.
DS2001-0236
2001
De Almeida Neto, A.P.De Almeida Neto, A.P.Angola, 2001Mining Annual Review 2001, 2p.AngolaCountry - overview, economics, mining, Overview - brief
DS1996-1119
1996
De Alvararenga, J.S.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
DS201701-0012
2016
De Andrade, V.Ganne, J., Feng, X., Rey, P., De Andrade, V.Statistical petrology reveals a link between supercontinents cycle and mantle global climate.American Mineralogist, Vol. 101, pp. 2768-2773.MantleGeostatistics

Abstract: The breakup of supercontinents is accompanied by the emplacement of continental flood basalts and dike swarms, the origin of which is often attributed to mantle plumes. However, convection modeling has showed that the formation of supercontinents result in the warming of the sub-continental asthenospheric mantle (SCAM), which could also explain syn-breakup volcanism. Temperature variations during the formation then breakup of supercontinents are therefore fundamental to understand volcanism related to supercontinent cycles. Magmatic minerals record the thermal state of their magmatic sources. Here we present a data mining analysis on the first global compilation of chemical information on magmatic rocks and minerals formed over the past 600 million years: a time period spanning the aggregation and breakup of Pangea, the last supercontinent. We show that following a period of increasingly hotter Mg-rich magmatism with dominant tholeiitic affinity during the aggregation of Pangea, lower-temperature minerals crystallized within Mg-poorer magma with a dominant calc-alkaline affinity during Pangea disassembly. These trends reflect temporal changes in global mantle climate and global plate tectonics in response to continental masses assembly and dispersal. We also show that the final amalgamation of Pangea at ~300 Myr led to a long period of lithospheric collapse and cooling until the major step of Pangea disassembly started at ~125 Myr. The geological control on the geosphere magma budget has implications on the oxidation state and temperature of the Earth’s outer envelopes in the Phanerozoic and may have exerted indirect influence on the evolution of climate and life on Earth.
DS201412-0451
2014
De Angelis, S.Kendrick, J.E., Lavallee, Y., Hirose, T., Di Toro,G., Hornby, A.J., De Angelis, S., Dingwell, D.B.Volcanic drumbeat seismicity caused by stick-slip motion and magmatic fictional melting.Nature Geoscience, Vol. 7, pp. 438-442.MantleMagmatism
DS2001-0134
2001
De AraujoBrod, J., Gaspar, De Araujo, Gibson, Thompson, JunqueiraPhlogopite and tetra ferriphlogopite from Brazilian carbonatite complexes and implications for systematicsJournal of African Earth Sciences, Vol. 19, No. 3, Apr. pp.265-296.BrazilCarbonatite, Mineral chemistry systematics
DS202002-0175
2019
de Araujo Neto, J.F.de Araujo Neto, J.F., de Brito Barreto, S., Carrino, T.A., Muller, A., de Lira Santos, L.C.M.Mineralogical and gemological characterization of emerald crystals from Parana deposit, NE Brazil: a study of mineral chemistry, absorption and reflectance spectroscopy and thermal analysis.Brazil Journal of Geology ( www.scielo.br) ENG, 15p. PdfSouth America, Brazildeposit - Parana

Abstract: The Paraná deposit, located at Southwestern Rio Grande do Norte state, in Brazil, is one of the few emerald deposits found at Borborema Province. The mineralization occurs in phlogopite schists and actinolite-phlogopite schists associated with pegmatites and albitites within the Portalegre Shear Zone. Unlike other well-known Brazilian emerald deposits, the mineralogy of Paraná emeralds has remained poorly investigated for the last 40 years. In this study, we conducted mineralogical characterization of theses emeralds through gemological testing, mineral chemistry, absorption and reflectance spectroscopy, and thermal analysis. The Paraná emeralds are bluish-green colored, characterized by high refractive index, several two-phase fluid inclusions and mica is the main mineral inclusion. Electron probe microanalysis and laser ablation-inductively coupled plasma-mass spectrometry analyses detected the presence of Fe2+ (0.43-1.94 wt.% FeO) and Cr3+ (0.04-0.14 wt.% Cr2O3) as the main chromophores replacing octahedral Al3+ in the crystal structure. In addition, substantial amounts of MgO (0.40-2.72 wt.%), Na2O (0.50-1.81 wt.%), and Cs2O (0.07-0.44 wt.%) were also identified. The main causes for its coloration were attributed to Cr3+ absorption features in visible spectral range, which were corroborated by absorption and reflectance spectra. The presence of types I and II H2O at channel-sites was recorded in Fourier-transform infrared spectra and demonstrated by dehydration processes observed in different thermal and thermogravimetric analyses.
DS201112-0253
2010
De Assis Janasi, V.De Assis Janasi, V., Andrade, S., Svisero, D.P.,Vieira de Almeida, V.Inferencias sobre a evolucao petrologica do manto no sudeste brasileiro a partir de microanalises de elementos traco em piroxenios e olivin a de xenolitos de espinelio peridotitos.5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 85.South America, BrazilPetrology of pyroxenes, olivines in xenoliths
DS201112-0720
2010
De Assis Janasi, V.Nannini, F., De Assis Janasi, V., Svisero, D.P.Quimica mineral de xenolitos do kimberlito indaia, Monte Carmelo, Minas Gerais.5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 84.South America, Brazil, Minas GeraisGeochemistry
DS201112-0721
2010
De Assis Janasi, V.Nannini, F., Svisero, D.P., De Assis Janasi, V.Petrografia de xenolitos mantelicos do kimberlito indaia, Mount Carmelo, Minas Gerais.5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 89.South America, Brazil, Minas GeraisPetrology
DS201112-1093
2010
De Assis Janasi, V.Viveira de Almeida, V., De Assis Janasi, V., Svisero, D.P.Mathiasita e priderita em xenolitos mantelicos do kimberlito Limeira, Monte Carmelo, Minas Gerais.5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 88.South America, Brazil, Minas GeraisPetrology
DS200812-0345
2008
De AstisFerrnado, 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
DS200812-1213
2008
De Azavedo, S.Viola, G., Henderson, I.H.C., Bingen, B., Thomas, R.J., Smethurst, M.A., De Azavedo, S.Growth and collapse of a deeply eroded orogen: insights from structural, geophysical, and geochronological constraints on Pan-African evolution of NE Mozambique.Tectonics, Vol. 27, TC5009Africa, MozambiqueGeochronology
DS201112-0391
2011
De BarrosGuarino, V., Azzone, Brotzu, De Barros, Melluso, L., Morbidelli, Ruberti, Tassinari, BrilliMagmatism and fenitization in the Cretaceous potassium alkaline carbonatitic complex of Ipanema, Sao Paulo State, Brazil.Mineralogy and Petrology, In press available,South America, BrazilCarbonatite
DS201312-0046
2013
De Barros Goes, C.Azzone, R.G., Enrich, G.E.R., De Barros Goes, C., Ruberti, E.Trace element composition of parental magmas from mafic-ultramafic cumulates by in situ mineral analyses: the Juquia mafic-ultramafic alkaline carbonatite massif, SE Brazil.Journal of South American Earth Sciences, Vol. 41, pp. 5-21.South America, BrazilCarbonatite
DS201212-0042
2012
De Barros Gomes, C.Azzone, R.G., Enrich, G.E.R., De Barros Gomes, C., Ruberti, E.Trace element composition of parental magmas from mafic-ultramafic cumulates determined by in situ mineral analyses: the Juquia mafic-ultramafic alkaline-carbonatite massif, SE Brazil.Journal of South American Earth Sciences, in press available, 17p.South America, BrazilAlkaline rocks, magmatism
DS201212-0268
2012
De Barros Gomes, C.Guarino, V., Wu, F-Y., Lustrino, M., Melluso, L.,Brotzu, P., De Barros Gomes, C., Ruberti, E., Tassarini, C.C.G., Svisero, D.P.U Pb ages, Sr Nd isotope geochemistry, and petrogenesis of kimberlites, kamafugites and phlogopite picrites of the Alto Paranaiba Igneous Province, Brazil.Chemical Geology, in press available 57p.South America, BrazilGeochronology
DS201709-1994
2017
de Barros Gomes, C.Guarino, V., Wu, F-Y., Melluso, L., de Barros Gomes, C., Tassinari, C.C.G., Ruberti, E., Brilli, M.U Pb ages, geochemistry, C-O-Nd-Sr-Hf isotopes and petrogeneis of the Catalao II carbonatitic complex ( Alto Paranaiba igneous province, Brazil): implucations for regional scale heterogeneities in the Brazilian carbonatite associations.International Journal of Earth Sciences, Vol. 106, 6, pp. 1963-1989.South America, Brazilcarbonatite - Catalao II

Abstract: The Catalão II carbonatitic complex is part of the Alto Paranaíba Igneous Province (APIP), central Brazil, close to the Catalão I complex. Drill-hole sampling and detailed mineralogical and geochemical study point out the existence of ultramafic lamprophyres (phlogopite-picrites), calciocarbonatites, ferrocarbonatites, magnetitites, apatitites, phlogopitites and fenites, most of them of cumulitic origin. U–Pb data have constrained the age of Catalão I carbonatitic complex between 78 ± 1 and 81 ± 4 Ma. The initial strontium, neodymium and hafnium isotopic data of Catalão II (87Sr/86Sri= 0.70503–0.70599; eNdi= -6.8 to -4.7; 176Hf/177Hf = 0.28248–0.28249; eHfi= -10.33 to -10.8) are similar to the isotopic composition of the Catalão I complex and fall within the field of APIP kimberlites, kamafugites and phlogopite-picrites, indicating the provenance from an old lithospheric mantle source. Carbon isotopic data for Catalão II carbonatites (d13C = -6.35 to -5.68 ‰) confirm the mantle origin of the carbon for these rocks. The origin of Catalão II cumulitic rocks is thought to be caused by differential settling of the heavy phases (magnetite, apatite, pyrochlore and sulphides) in a magma chamber repeatedly filled by carbonatitic/ferrocarbonatitic liquids (s.l.). The Sr–Nd isotopic composition of the Catalão II rocks matches those of APIP rocks and is markedly different from the isotopic features of alkaline-carbonatitic complexes in the southernmost Brazil. The differences are also observed in the lithologies and the magmatic affinity of the igneous rocks found in the two areas, thus demonstrating the existence of regional-scale heterogeneity in the mantle sources underneath the Brazilian platform.
DS2003-1112
2003
De Bayle, E.Priestly, K., De Bayle, E.Seismic evidence for a moderately thick lithosphere beneath the Siberian PlatformGeophysical Research Letters, Vol. 30, 3, Feb. 1, p. 18.RussiaGeophysics - seismics
DS200412-1590
2003
De Bayle, E.Priestly, K., De Bayle, E.Seismic evidence for a moderately thick lithosphere beneath the Siberian Platform.Geophysical Research Letters, Vol. 30, 3, Feb. 1, p. 18.RussiaGeophysics - seismics
DS200512-0417
2005
De Bayle, E.Heintz, M., De Bayle, E., Vauchez, A.Upper mantle structure of the South American continent and neighbouring oceans from surface wave tomography.Tectonophysics, Vol. 406, 1-2, pp. 115-139.South AmericaTomography
DS200812-1186
2007
De Beer, C.Trumbull, R.B., Reid, D.L., De Beer, C., Van Acken, D., Romer, R.L.Magmatism and continental breakup at the west margin of southern Africa: a geochemical comparison of dolerite dikes from northwestern Namibia and the Western Cape.South African Journal of Geology, Vol. 110, 2-3, Sept. pp. 477-502.Africa, South Africa, NamibiaMagmatism
DS1998-0532
1998
De Beer, C.H.Gresse, P.G., Thomas, R.J., De Beer, C.H., De Kock, G.S.The development of the Anti Atlas Orogen, Morocco: parallels with the Pan-African belts of southern AfricaJournal of African Earth Sciences, Vol. 27, 1A, p. 92. AbstractMoroccoOrogeny
DS2003-1124
2003
De Beer, C.H.Raith, J.G., Cornell, D.H., Frimmel, H.E., De Beer, C.H.New insights into the geology of the Namaqua tectonic province, South Africa, from ionJournal of Geology, Vol. 111, 3, pp. 347-66.South AfricaTectonic - zone, Geochronology
DS200412-1610
2003
De Beer, C.H.Raith, J.G., Cornell, D.H., Frimmel, H.E., De Beer, C.H.New insights into the geology of the Namaqua tectonic province, South Africa, from ion probe dating of detrital and metamorphicJournal of Geology, Vol. 111, 3, pp. 347-66.Africa, South AfricaTectonic - zone Geochronology
DS1970-0696
1973
De beer, J.H.Gough, D.I., De beer, J.H., Van zijl, J.S.V.A Magnetometer Array Study in Southern AfricaRoy. Astron. Soc. Geophys. Journal, Vol. 34, PP. 421-433.South Africa, BotswanaGeophysics
DS1975-0064
1975
De beer, J.H.De beer, J.H., Gough, D.I., Van Zijl, J.S.V.An Electrical Conductivity Anomaly and Rifting in Southern Africa. #1Nature., Vol. 225, PP. 678-680.South Africa, BotswanaGeophysics, Tectonics
DS1975-0065
1975
De beer, J.H.De beer, J.H., Gough, D.I., Van Zyjl, J.S.V.An Electrical Conductivity Anomaly and Rifting in Southern Africa. #2Nature., Vol. 255, JUNE 26TH, PP. 678-680.BotswanaGeotectonics, Geophysics
DS1975-0268
1976
De beer, J.H.De beer, J.H., Van zijl, J.S.V., Huyssen, R.M.J., Hugo, P.L.V.A Magnetometer Array Study in Southwest Africa, Botswana And Rhodesia.Roy. Astron. Soc. Geophys. Journal, Vol. 45, PP. 1-17.Southwest Africa, Namibia, Botswana, ZimbabweGeophysics
DS1975-0991
1979
De beer, J.H.De beer, J.H.The Tectonic Significance of Geomagnetic Induction Anomalies in Botswana and Southwest Africa.Botswana Geological Survey, Bulletin. No. 22, PP. 297-339.Botswana, Southwest Africa, Namibia, ZimbabweRegional Tectonics
DS1980-0104
1980
De beer, J.H.De beer, J.H., Gough, D.I.Conductive Structures in Southern Most Africa. a Magnetometer Array Study.Roy. Astron. Soc. Geophys. Journal, Vol. 63, No. 2, PP. 479-495.South Africa, BotswanaTectonics, Geophysics
DS1988-0160
1988
De Beer, J.H.De Beer, J.H., Stettler, E.H.Geophysical characteristics of the southern African continental crustJournal of Petrology, Special Volume 1988- Oceanic and Continental, pp. 163-184South AfricaGeophysics
DS1988-0669
1988
De Beer, J.H.Stettler, E.H., Du Plessis, J.G., De Beer, J.H.The structure of the Pietersburg greenstone belt, South Africa, as derived from geophysicsSouth African Journal of Geology, Vol. 91, No. 2, June pp. 292-303. Database # 17372South AfricaGreenstone Belt, Geophysics
DS1988-0728
1988
De Beer, J.H.Vearncombe, J.R., Cheshire, P.E., De Beer, J.H., Killick, A.M.Structures related to the Antimony line, Murchison schist belt,Kaapvalcraton, South AfricaTectonophysics, Vol. 154, No. 3/4, November 10, pp. 285-308South AfricaTectonics, Craton
DS1989-1456
1989
De Beer, J.H.Stettler, E.H., De Beer, J.H., Blom, M.P.Crustal domains in the Northern Kaapvaal craton as defined by magneticlineamentsPrecambrian Research, Vol. 45, pp. 263-276South AfricaCraton, Geophysics -magnetics
DS1992-1287
1992
De Beer, J.H.Roering, C., Van Reenen, D.D., Smit, C.A., Barton, J.M.Jr., De Beer, J.H.Tectonic model for the evolution of the Limpopo BeltPrecambrian Research, Vol. 55, pp. 539-552South AfricaTectonics, Limpopo Belt
DS200812-0268
2008
De BeersDe BeersDe Beers rolls the dice in Angola.De Beers, Feb. 22, 2p.Africa, AngolaNews item - De Beers
DS200912-0162
2009
De Beers Canada Inc.De Beers Canada Inc.Kitchenuhmaykoosib Inninuwug and De Beers Canada hold discussions.De Beers Canada Inc., August 25, 1/8p.Canada, OntarioNews item - legal
DS2003-0639
2003
De Belder, D.Jago, B.C., Lindsay, J., De Belder, D., Davis, D.W.Diamond grade and quality in relation to mineral chemistry of Twin Mining's Jackson31st Yellowknife Geoscience Forum, p. 46. (abst.Nunavut, Brodeur PeninsulaMineral chemistry
DS200412-0896
2003
De Belder, D.Jago, B.C., Lindsay, J., De Belder, D., Davis, D.W.Diamond grade and quality in relation to mineral chemistry of Twin Mining's Jackson In let FreightTrain kimberlite, Brodeur Penin31st Yellowknife Geoscience Forum, p. 46. (abst.Canada, Nunavut, Brodeur PeninsulaMineral chemistry
DS1996-1564
1996
De Bels, M.Wyatt, B.A., Colgan, J.J., Smit, E.A., De Bels, M.Some aspects of the petrology and mineral chemistry of the Ningxianglamproites, Hunan Province.International Geological Congress 30th Session Beijing, Abstracts, Vol. 2, p. 400.ChinaLamproites, Petrology, geochemistry
DS1995-0400
1995
De Bjerg, S.C.De Bjerg, S.C., et al.PASFORM - a program for IBM compatibles to calculate mineral formulae from electron microprobe and wet cheM.Computers and Geosciences, Vol. 21, No. 10, pp. 1187-1190GlobalComputer, Program -PASFORM.
DS2001-1147
2001
De BlondTack, L., Wingate, Ligeois, Fernandez-Alonzo, De BlondEarly Neoproterozoic magmatism 1000-910 Ma of the Zadinia and Mayumbian groups: onset of Rodinia riftingPrecambrian Research, Vol. 110, pp. 277-306.GlobalMagmatism, Craton - Congo
DS2001-0237
2001
De Boeck, F.De Boeck, F.Garimpeiro worlds: digging, dying and hunting for diamonds in AngolaReview of African Political Policy, Vol. 90, pp. 549-62.AngolaNews item, History, conflict diamonds
DS1995-2055
1995
De Boorder, H.White, S.H., De Boorder, H., Smith, C.B.Structural controls on the emplacement of kimberlites and lamproitesJournal of Geochemical Exploration, Vol. 52, pp. 245-264.AustraliaDiamond exploration, Structure
DS1997-0257
1997
De Boorder, H.De Boorder, H., Van Beek, A.J.J., Panov, B.S.Crustal architecture of the Donets Basin: tectonic implications for diamond and mercury-antimony mineralsTectonophysics, Vol. 268, No. 1/4, Dec. 31, pp. 293-UKraineTectonics, Structure, Diamond mineralization, genesis
DS1997-0623
1997
De Boorder, H.Koroteev, V.A., De Boorder, H., Sazonov, V.N.Geodynamic setting of the mineral deposits of the UralsTectonophysics, Vol. 276, No. 1-4, July 30, pp. 291-300GlobalGeodynamics, tectonics, Deposits
DS200712-0343
2007
De Bremond d'Ars, J.Galland, O., Cobbold, P.R., De Bremond d'Ars, J., Hallot, E.Rise and emplacement of magma during horizontal shortening of the brittle crust: insights from experiments.Journal of Geophysical Research, Vol. 112, B6 B06402MantleMagmatism
DS2002-0366
2002
De Bresser, H.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
De Bresser, H.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
De Bresser, J.H.P.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
DS202002-0175
2019
de Brito Barreto, S.de Araujo Neto, J.F., de Brito Barreto, S., Carrino, T.A., Muller, A., de Lira Santos, L.C.M.Mineralogical and gemological characterization of emerald crystals from Parana deposit, NE Brazil: a study of mineral chemistry, absorption and reflectance spectroscopy and thermal analysis.Brazil Journal of Geology ( www.scielo.br) ENG, 15p. PdfSouth America, Brazildeposit - Parana

Abstract: The Paraná deposit, located at Southwestern Rio Grande do Norte state, in Brazil, is one of the few emerald deposits found at Borborema Province. The mineralization occurs in phlogopite schists and actinolite-phlogopite schists associated with pegmatites and albitites within the Portalegre Shear Zone. Unlike other well-known Brazilian emerald deposits, the mineralogy of Paraná emeralds has remained poorly investigated for the last 40 years. In this study, we conducted mineralogical characterization of theses emeralds through gemological testing, mineral chemistry, absorption and reflectance spectroscopy, and thermal analysis. The Paraná emeralds are bluish-green colored, characterized by high refractive index, several two-phase fluid inclusions and mica is the main mineral inclusion. Electron probe microanalysis and laser ablation-inductively coupled plasma-mass spectrometry analyses detected the presence of Fe2+ (0.43-1.94 wt.% FeO) and Cr3+ (0.04-0.14 wt.% Cr2O3) as the main chromophores replacing octahedral Al3+ in the crystal structure. In addition, substantial amounts of MgO (0.40-2.72 wt.%), Na2O (0.50-1.81 wt.%), and Cs2O (0.07-0.44 wt.%) were also identified. The main causes for its coloration were attributed to Cr3+ absorption features in visible spectral range, which were corroborated by absorption and reflectance spectra. The presence of types I and II H2O at channel-sites was recorded in Fourier-transform infrared spectra and demonstrated by dehydration processes observed in different thermal and thermogravimetric analyses.
DS2000-0211
2000
De Brito Neves, B.B.De Almeida, F.F.M., De Brito Neves, B.B., CarneiroThe origin and evolution of the South American PlatformEarth Science Reviews, Vol. 14, pp. 77-111.South America, Brazil, BoliviaTectonics - shield, Craton, platform, Proterozoic, Archean Phanerozoic
DS200412-0405
2004
De Brito Neves, B.B.Dantas, E.L., Van Schmus, W.R., Hackspacher, P.C., Fetter, A.H., De Brito Neves, B.B., Cordani, U., Nutman, A.The 3.4 3.5 Ga Sao Jose do Campestre Massif, NE Brazil: remnants of the oldest crust in South America.Precambrian Research, Vol. 130, 1-4, April 20, pp. 113-137.South America, BrazilGeochronology, Borborema
DS200512-0683
2005
De Brito Neves, B.B.Mantovani, M.S.M., De Brito Neves, B.B.The Paranapanema lithospheric block: its importance for Proterozoic (Rodinia, Gondwana) supercontinent theories.Gondwana Research, Vol. 8, 3, pp. 303-315.South America, BrazilTectonics, Amazon, Sao Francisco, La Plata cratons
DS1982-0172
1982
De brooder, H.De brooder, H.Deep Reaching Fracture Zones in the Crystalline Basement Surrounding the West Congo System and Their Control of Mineralization in Angola and Gabon. #2Tectonophysics, Vol. 20, No. 3-4, PP. 259-273.Angola, Gabon, Central AfricaTectonics, Diamond, Kimberlite, Geophysics
DS1995-0384
1995
De BruinDaniels, L.R.M., Richardson, S.H., Menzies, A.H., De BruinDiamondiferous garnet macrocrysts in the Newlands kimberlite, South Africa-rosetta stones from KaapvaalProceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 121-123.South AfricaHarzburgites, Deposit -Newlands
DS1989-0340
1989
De Bruin, D.De Bruin, D.Mantle eclogites from the Schuller kimberlite,Transvaal, South SOURCE[ South African Journal of GeolSouth African Journal of Geol, Vol. 92, No. 2, pp. 134-145South AfricaEclogite, Geochemistry
DS1990-0394
1990
De Bruin, D.De Bruin, D.Clinopyroxene megacrysts from the Schuller kimberlite Transvaal, SouthAfricaInternational Mineralogical Association Meeting Held June, 1990 Beijing China, Vol. 2, extended abstract p. 791-792South AfricaClinopyroxenes, Schuller kimberlite
DS1993-0333
1993
De Bruin, D.De Bruin, D.The megacryst suite from the Schuller kimberlite, South AfricaSouth Africa Geological Survey Bulletin, No. 114, 115p. $ 30.00 plus $ 40.00 for airmail($10.00)South AfricaMineral chemistry, Deposit -Schuller
DS1995-0401
1995
De Bruin, D.De Bruin, D.Clinopyroxene megacrysts from the Kalput kimberlite: a Group 2 kimberlite from the Prieska Group kimberlitesProceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 71-73.South AfricaKaapvaal craton area, Deposit -Kalput
DS1998-0317
1998
De Bruin, D.De Bruin, D.Inclusion bearing chromium poor and chromium rich garnet megacrysts from the Group II Swartruggens kimberlite.7th International Kimberlite Conference Abstract, pp. 181-183.South AfricaFissure intrusions, mineral chemuistry, Deposit - Swartruggens
DS1998-0793
1998
De Bruin, D.Kostrovitsky, S.I., De Bruin, D.Ultramafic association of minerals ( garnet ureyite diopside chromspinelid)in micacous kimberlites..7th International Kimberlite Conference Abstract, pp. 463-5.Russia, YakutiaPetrology, Deposit - Zagadochnaya, Kusov, Bukovinskaya, Gornyatska
DS2000-0528
2000
De Bruin, D.Kostrovitsky, S.I., Chernysheva, E.A., De Bruin, D.The compositional features of kimberlites on the eastern slope of the Anabar Shield, Russia, Yakutia.Igc 30th. Brasil, Aug. abstract only 1p.Russia, YakutiaMesozoic kimberlite volcanism., Geochemistry
DS200512-0221
2005
De Bruin, D.De Bruin, D.Multiple compositional megacryst groups from the Uintjiesberg and Witberg kimberlites.South African Journal of Geology, Vol. 108, 2, pp. 233-246.Africa, South AfricaPetrology
DS200512-0570
2004
De Bruin, D.Kostrovitsky, S.I., De Bruin, D.Chromium assemblage of minerals in micaceous kimberlites of Yakutian province.Russian Geology and Geophysics, Vol. 45, 5, pp. 521-535.Russia, YakutiaMineral chemistry - chromite
DS200512-0571
2004
De Bruin, D.Kostrovitsky, S.I., De Bruin, D.Chromium assemblage of minerals in micaceous kimberlites of Yakutian province.Russian Geology and Geophysics, Vol. 45, 5, pp. 521-35.Russia, YakutiaMineralogy
DS201012-0139
2010
De Bruin, D.De Bruin, D.Evaluation of a quality control monitor material for the routine electron probe microanalysis of kimberlite exploration garnets.Geostandards and Geoanalytical Research, Vol. 34, 3, pp. 257-264.TechnologyGarnet analyses
DS201212-0142
2012
De Bruin, D.Daniels, L.R.M., De Bruin, D., Smuts, J.C.Exploration for concealed kimberlites in Botswana with trace element soil geochemistry.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractAfrica, BotswanaGeochemistry - trace elements
DS201212-0150
2012
De Bruin, D.De Bruin, D., Barton, E., Simneti, A.The Sr isotope compositions of clinopyroxene megacrysts determined by ICP-MS-LA from localities across the Kaapvaal Craton through the ages.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractAfrica, South AfricaGeochemistry
DS201212-0151
2012
De Bruin, D.De Bruin, D., Graser, P.Quality control procedures applied to routine electron probe analyses of kimberlite indicator minerals.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractTechnologyGeochemistry - KIMS
DS201708-1622
2017
De Bruin, D.De Bruin, D.The mineral chemistry of the megacryst suite from the Schuller and Premier kimberlites.11th. International Kimberlite Conference, PosterAfrica, South Africadeposit - Schuller, Premier
DS201112-0707
2011
De Bruin, S.Mulder, V.L., De Bruin, S., Schaepman, T.R., et al.The use of remote sensing in soil and terrain mapping - a review.Geoderma, Vol. 162, 1-2, pp. 1-19.TechnologySoils - review not specific to diamonds
DS2000-0212
2000
De Bruiyn, H.De Bruiyn, H., Schoch, Van der Westhuizen, MyburghPicrite from the Katse area, Lesotho: evidence for flow differentiationJournal of African Earth Sciences, Vol. 31, No. 3-4, pp. 657-88.LesothoPicrite, Geochemistry - magma
DS1992-1054
1992
de Bruyn, H.D.Meyer, F.M., Robb, L.J., Reimold, W.U., de Bruyn, H.D.Sulphur and Iodine type granites during late stage magmatism in the Barberton Mountain Land, southern AfricaEconomic Geology Research Unit, University of of Witwatersrand, Information Circular No. 257, 18pSouth AfricaGranites, Magmatism
DS1984-0221
1984
De camargo, W.G.R.De camargo, W.G.R.Oriented Intergrowth of Corundum in Diamond CrystalsActa Crystallographica Sect. A. Foundations of Crystallograp, Vol. 40, SUPPL. P. C251. (abstract.).BrazilCrystallography
DS200612-0157
2006
De Capitani, C.Bousquet, R., De Capitani, C., Arcay, D.Feedback of the metamorphic changes on the subducting processes.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 1, abstract only.MantleSubduction
DS201112-0340
2011
De Capitani, C.Gaidoes, F., Pattison, D.R.M., De Capitani, C.Toward a quantitative model of metamorphic nucleation and growth.Contributions to Mineralogy and Petrology, Vol. 162, 5, pp.975-1009.MantleContinent accretion
DS1990-0216
1990
De Capitani, L.Bocchio, R., De Capitani, L., Liborio, G., Maresch, W.V., MottanaThe eclogite bearing series of Isla Margarita, Venezuela: geochemistry of metabasic lithologies in the la Rinconada and Juan Griego GroupsLithos, Vol. 25, No. 1-3, November pp. 55-70VenezuelaEclogites, Geochemistry
DS1992-0349
1992
De Caritat, P.De Caritat, P., Braun, J.Cyclic development of sedimentary basins at convergent plate margins - 1.structural and tectono-thermal evolution of some Gondwana Basins of easternAustraliaJournal of Geodynamics, Vol. 16, No. 4, pp. 241-282AustraliaBasins, Structure
DS1998-1227
1998
de Caritat, P.Reimann, C., de Caritat, P.Chemical elements in the environmentSpringer, 410p. $ approx. $ 110.0 United StatesGlobalBook - ad, Geochemistry, environment, metals, analytical
DS201912-2787
2019
de Caritat, P.Grunsky, E.C., de Caritat, P.State of the art analysis of geochemical data for mineral exploration. ( not specific to diamonds)Geochemistry: Exploration, Environment, Analysis, http://doi.org/10.1144/ geochem2019-031 16p. PdfCanada, Nunavut, Australiageochemistry

Abstract: Multi-element geochemical surveys of rocks, soils, stream/lake/floodplain sediments and regolith are typically carried out at continental, regional and local scales. The chemistry of these materials is defined by their primary mineral assemblages and their subsequent modification by comminution and weathering. Modern geochemical datasets represent a multi-dimensional geochemical space that can be studied using multivariate statistical methods from which patterns reflecting geochemical/geological processes are described (process discovery). These patterns form the basis from which probabilistic predictive maps are created (process validation). Processing geochemical survey data requires a systematic approach to effectively interpret the multi-dimensional data in a meaningful way. Problems that are typically associated with geochemical data include closure, missing values, censoring, merging, levelling different datasets and adequate spatial sample design. Recent developments in advanced multivariate analytics, geospatial analysis and mapping provide an effective framework to analyse and interpret geochemical datasets. Geochemical and geological processes can often be recognized through the use of data discovery procedures such as the application of principal component analysis. Classification and predictive procedures can be used to confirm lithological variability, alteration and mineralization. Geochemical survey data of lake/till sediments from Canada and of floodplain sediments from Australia show that predictive maps of bedrock and regolith processes can be generated. Upscaling a multivariate statistics-based prospectivity analysis for arc-related Cu-Au mineralization from a regional survey in the southern Thomson Orogen in Australia to the continental scale, reveals a number of regions with a similar (or stronger) multivariate response and hence potentially similar (or higher) mineral potential throughout Australia.
DS201612-2309
2016
De Carlo, F.Kaercher, P., Miyagi, L., Kanitpanyacharoen, W., Zepeda-Alarcon, E., Wang, Y., Parkinson, D., Lebensohn, R.A., De Carlo, F., Wenk, H.R.Two phase deformation of lower mantle mineral analogs.Earth and Planetary Science Letters, Vol. 456, pp. 134-145.MantleBridgemanite

Abstract: The lower mantle is estimated to be composed of mostly bridgmanite and a smaller percentage of ferropericlase, yet very little information exists for two-phase deformation of these minerals. To better understand the rheology and active deformation mechanisms of these lower mantle minerals, especially dislocation slip and the development of crystallographic preferred orientation (CPO), we deformed mineral analogs neighborite (NaMgF3, iso-structural with bridgmanite) and halite (NaCl, iso-structural with ferropericlase) together in the deformation-DIA at the Advanced Photon Source up to 51% axial shortening. Development of CPO was recorded in situ with X-ray diffraction, and information on microstructural evolution was collected using X-ray microtomography. Results show that when present in as little as 15% volume, the weak phase (NaCl) controls the deformation. Compared to single phase NaMgF3 samples, samples with just 15% volume NaCl show a reduction of CPO in NaMgF3 and weakening of the aggregate. Microtomography shows both NaMgF3 and NaCl form highly interconnected networks of grains. Polycrystal plasticity simulations were carried out to gain insight into slip activity, CPO evolution, and strain and stress partitioning between phases for different synthetic two-phase microstructures. The results suggest that ferropericlase may control deformation in the lower mantle and reduce CPO in bridgmanite, which implies a less viscous lower mantle and helps to explain why the lower mantle is fairly isotropic.
DS2000-0213
2000
De Carvalho, H.De Carvalho, H., Tassinari, C., Alvesm P.H., GuimaraesGeochronological review of the Precambrian in western Angola: links with Brasil.Journal of African Earth Sciences, Vol. 31, No. 2, Aug. pp. 383-402.Angola, BrazilGeochronology, Tectonics - Congo, Sao Francisco Craton
DS1984-0528
1984
De carvalho, M.P.Moneteiro, M.D., De carvalho, M.P., Filho, V.M.C.Caracterizacao faciologica e sistemas deposcionais do grupo ChapadaDiamantina.Anais Do XXXIII Brasileiro de Geologia, pp. 1090-1105.Brazil, BahiaChapada Diamantia, Sedimentology
DS2002-0364
2002
De Carvalho, R.G.De Carvalho, R.G.The Portuguese crown jewels18th. International Mineralogical Association Sept. 1-6, Edinburgh, abstract p.146.BrazilDiamond - history
DS201802-0230
2018
De Carvallo, L.D.V.De Carvallo, L.D.V., Schnellrath, J., de Medeiros, S.G.Mineral inclusions in diamonds from Chapada Diamantina, Bahia, Brazil: a raman spectroscopic characterization, REM ****IN PORTInternational Engineering Journal, Ouro Preto *** IN: PORT, Vol. 71, 1, pp. 27-35.South America, Brazildeposit - Chapada

Abstract: The Chapada Diamantina, located in the central region of the State of Bahia, is of important historical significance due to its diamond occurrences. Discovered in the nineteenth century, comprehensive research about the regional diamonds and their origins are still limited, demanding more investigation in the matter. Looking for insights about their genesis, mineral inclusions in 23 alluvial diamonds from 4 garimpos located in the Chapada Diamantina were analyzed through the use of Raman micro spectroscopy. Additionally, the characteristics of nitrogen aggregation of the host diamonds were measured using Fourier-transform infrared spectroscopy (FTIR). The diamonds from Chapada Diamantina consist mainly of well-formed crystals, with dominant dodecahedral habits, characterized by faint to very light yellow body colors, typically with green and brown radiation spots on their surface. The main surface textures observed are related to processes that took place in the late stage resorption and during the residence of the diamonds in placer environments. The diamonds are predominantly type IaAB, with a significant occurrence of poorly aggregated nitrogen (Type IaA diamond). The main mineral assemblages of the studied peridotitic inclusions refer to a harzburgitic paragenesis.
DS201312-0100
2013
De Castro Valente, S.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
DS1994-0405
1994
De Celles, P.G.De Celles, P.G.Late Cretaceous-Paleocene synorogenic sedimentation and kinematic history of the Sevier thrust belt, Utah and WyomingGeological Society of America Bulletin, Vol. 106, No. 1, January pp. 32-56Utah, WyomingTectonics, Stratigraphy
DS1997-0522
1997
De Celles, P.G.Horton, B.K., De Celles, P.G.The modern foreland basin system adjacent to the Central AndesGeology, Vol. 25, No. 10, Oct., pp. 895-98Bolivia, Andes, Argentina, Paraguay, BrazilBasin - foreland, Sedimentary
DS2002-1067
2002
De Cesero, P.Mizusaki, A.M., ThomasFilho, A., Milani, B.J., De Cesero, P.Mesozoic and Cenozoic igneous activity and its tectonic control in northeastern BrasilJournal of South American Earth Sciences, Vol. 15, No. 2, pp. 183-98.BrazilTectonics
DS2002-1068
2002
De Cesero, P.Mizusaki, A.M.P., Thomas-Filho, A., Milani, E.J., De Cesero, P.Mesozoic and Cenozoic igneous activity and its tectonic control in northeastern BrasilJournal of South American Earth Sciences, Vol.15,2,June pp. 183-98.BrazilTectonics, Magmatism - not specific to diamonds
DS201506-0268
2015
de Clarens, P.Frizon de Lamotte, D., Fourdan, B., Leleu, S., Leparmentier, F., de Clarens, P.Style of rifting and the stages of Pangea break up.Tectonics, Vol. 34, 5, pp. 1009-1029.Global, RussiaPangea
DS202006-0939
2020
De Clarens, P.Moulin, M., Aslainian, D., Evain, M., Lepetre, A., Schnurle, P., Verrier, F., Thompson, J., De Clarens, P., Leroy, S., Dias, N.Gondwana breakup: messages from the north Natal Valley.Terra Nova, Vol. 32, 3, pp. 205-210.Africa, Mozambiquegeophysics - seismics

Abstract: The Natal Valley, offshore Mozambique, is a key area for understanding the evolution of East Gondwana. Within the scope of the integrated multidisciplinary PAMELA project, we present new wide-angle seismic data and interpretations, which considerably alter Geoscience paradigms. These data reveal the presence of a 30-km-thick crust that we argue to be of continental nature. This falsifies all the most recent palaeo-reconstructions of the Gondwana. This 30-km-thick continental crust 1,000 m below sea level implies a complex history with probable intrusions of mantle-derived melts in the lower crust, connected to several occurrences of magmatism, which seems to evidence the crucial role of the lower continental crust in passive margin genesis.
DS1991-0352
1991
De Cola, L.De Cola, L.Multifractals in image processing and process imagingUnited States Geological Survey (USGS) Open File, No. 91-0301, 23p. $ 4.25GlobalComputer, Program -multifractals
DS2002-0682
2002
De Conto, R.M.Hay, W.W., Soeding, E., De Conto, R.M., Wold, C.N.The late Cenozoic uplift - climate change paradoxInternational Journal of Earth Sciences, Vol. 91, No. 5, Oct. pp. 746-74.GlobalGeomorphology - climate change
DS1998-0220
1998
De CorteCartigny, P., De Corte, Shatsky, Sobolev, JavoyMicrodiamonds from ultra high pressure (UHP) metamorphic rocks of the Kokchetav massif and bearing on carbon and nitrogen ...Mineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 276-7.RussiaSubduction, Deposit - Kokchetav
DS1998-1329
1998
De CorteShatsky, V.S., Zedgenizov, Yefimova, Rylov, De CorteA comparison of morphology and physical properties of microdiamonds From the mantle and crustal environments7th International Kimberlite Conference Abstract, pp. 797-9.Russia, YakutiaDiamond morphology - microdiamonds, Deposit - Udachanya, Sytykanskaya
DS1999-0656
1999
De CorteShatsky, V.S., Zedgenizov, Yefimova, Rylov, De CorteA comparison of morphology and physical properties of microdiamonds from the mantle and crustal environments.7th International Kimberlite Conference Nixon, Vol. 2, pp. 757-63.Russia, Kokchatav Massif, Australia, WesternMicro diamonds, metamorphic rocks, Deposit - Udachnaya, Sytykanskaya
DS1998-0029
1998
De Corte, K.Andre, L., Shatsky, V.S., De Corte, K., Sobolev, N.V.Potassium rich clinopyroxenes as mantle conveyers of crustal derived components.7th International Kimberlite Conference Abstract, pp. 17-19.Australia, RussiaMicroanalyses - omphacite, clinopyroxene, Deposit - Argyle, Kochetav Massif
DS1998-0318
1998
De Corte, K.De Corte, K., Cartigny, P., Shatsky, De Paepe, SobolevMicrodiamonds from ultra high pressure (UHP) metamorphic rocks of Kokchetav Massif, northernKazakstan: FTIR spectroscopy....7th International Kimberlite Conference Abstract, pp. 184-186.Russia, KazakhstanMetamorphic rocks, diamond morphology, Deposit - Kokchetav
DS1998-0319
1998
De Corte, K.De Corte, K., Cartigny, P., Shatsky, Sobolev, JavoyEvidence of fluid inclusions in metamorphic microdiamonds from the Kokchetav Massif.Geochimica et Cosmochimica Acta, Vol. 62, No. 23/24, Dec. pp. 3765-73.Russia, KazakhstanMicrodiamonds, nitrogen, Deposit - Kokchetav Massif
DS200512-0222
2005
De Corte, K.De Corte, K., Kerremans, Y., Nouwen, B., Van Royen, J.Characterization of carbonado used as a gem.Gemmologie: Zeitschrift der Deutschen Gemmologischen Gesellschaft ** In GERMAN, Vol. 53, 1, pp. 5-22.Diamond - carbonado
DS200512-1094
2005
De Corte, K.Tomlinson, E., De Schrijver, I., De Corte, K., Jones, A.P., Moens, L., Vanhaecke, F.Trace element compositions of submicroscopic inclusions in coated diamond: a tool for understanding diamond petrogenesis.Geochimica et Cosmochimica Acta, Vol. 69, 19, Oct. 1, pp. 4719-4732.Africa, Democratic Republic of CongoSilicate melt inclusions, Group 1, diamond inclusions
DS200712-0225
2006
De Corte, K.De Corte, K., Anthonis, A., Van Royen, J., Blancaert, M., Barjon, J., Willems, B.Overview of dislocation networks in natural type IIa diamonds.Gems & Gemology, 4th International Symposium abstracts, Fall 2006, p.122-3. abstract onlyTechnologyDiamond Type IIa
DS201212-0123
2012
De Corte, K.Chapman, J., De Corte, K., Van Royen, J., Willems, B.FTIR features in Argyle, Diavik and Murowa diamonds.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractAfrica, ZimbabweDeposit - Murowa
DS201901-0002
2018
De Corte, K.Anthonis, A., Chapman, J., Smans, S., Bouman, M., De Corte, K.Fluorescence in diamond: new insights.Gems & Gemology, Sixth International Gemological Symposium Vol. 54, 3, 1p. Abstract p. 265-6.GlobalFluoresence

Abstract: The effect of fluorescence on the appearance of diamonds has been a subject of debate for many years (Moses et al., 1997). In the trade, fluorescence is generally perceived as an undesirable characteristic. Nearly 80% of diamonds graded at HRD Antwerp receive a “nil” fluorescence grade, while the remainder are graded as “slight,” “medium,” and “strong,” their value decreasing with level of fluorescence. To understand how fluorescence might change diamond appearance, a selection of 160 round brilliant-cut diamonds were investigated in detail. This study focused on the effect of thetic samples, it is possible that some of the observed phosphorescence does not involve boron impurities. In this paper we report on the results of combined fluorescence, phosphorescence, thermoluminescence, and quantitative charge transfer investigations undertaken on both HPHT and CVD synthetic diamond, with the objective of identifying which defects are involved in the fluorescence and phosphorescence processes.
DS201904-0720
2019
De Corte, K.Bouman, M., Anthonis, A., Chapman, J., Smans, S., De Corte, K.The effect of blue fluorescence on the colour appearance of round brilliant cut diamonds.Journal of Gemology, Vol. 36, 4, pp. 298-315.Globaldiamond fluoresence
DS1986-0171
1986
De Decker, R.H.De Decker, R.H.The geological setting of Diamondiferous deposits on the inner shelf between the Orange River and Wreck Point, NamaqualandBulletin. Joint Geological Survey/University of Cape Town, Marine Geoscience Group, Vol. 16, 280p. 200 refsSouth AfricaBlank
DS1988-0161
1988
De Decker, R.H.De Decker, R.H.The geological setting of the Diamondiferous deposit son the inner shelf between the Orange River and WreckPoint, NamaqualandSouth African Geological Survey, Bulletin. No. 86South AfricaAlluvials, Orange River
DS1991-0353
1991
De Decker, R.H.De Decker, R.H., Lyle, S.D., Woodborne, M.W.Marine diamonds: the geological controls governing the marine and terrestrial diamond deposits occurring along the West Coast of the Republic of South AfricaIndiaqua, Industrial Diamond ANNUAL, 1991 pp. 53-56, 58-59South AfricaMarine diamonds, alluvials, Overview
DS1995-2072
1995
De Decker, R.H.Woodborne, M.W., De Decker, R.H., Gurney, J.J., Smith, H.S.The marine geology of two mid water diamond concession areas off the Namaqualand coast... environments.Exploration and Mining Geology, Vol. 4, No. 1, p. 90-91.South AfricaMarine mining
DS1995-2073
1995
De Decker, R.H.Woodborne, M.W., De Decker, R.H., Hollick, P.C., Gurney, J.New information on wave cut terraces and the importance in relation To diamond deposits on west coast South AfricaExploration and Mining Geology, Vol. 4, No. 1, p. 91.South AfricaMarine mining, Terraces
DS1996-0347
1996
De Decker, R.H.De Decker, R.H., Woodborne, M.W.Geological and technical aspects of marine diamond exploration in southernAfrica.Offshore Technology Conference, 27th., pp. 561-572.South Africa, NamibiaMarine mining, placers, Distribution of west coast diamond fields
DS201412-0174
2014
De Deus Borges, L.A.De Deus Borges, L.A., Chaves, M.L.S.C.Mineralogia e aspectos da dissolucao nos diamantes do Rio Borrachudo ( Tiros, MG).6 Simposio Brasileiro de Geologia do Diamante, Aug. 3-7, 1p. AbstractSouth America, Brazil, Minas GeraisSao Francisco area
DS1998-0278
1998
De Figueiredo, L.L.Corsini, M., De Figueiredo, L.L., Vauchez, A.Thermal history of the Pan-African Brasiliano Borborema Province of northeast Brasil from 40Kr 39 Kr analysisTectonophysics, Vol. 285, No. 1-2, Feb. 15, pp. 103-118BrazilGeothermometry, Borborema
DS201911-2560
2019
de Fourestier, J.Schumann, D., Martin, R.F., Fuchs, S., de Fourestier, J.Silicocarbonatitic melt inclusions in fluorapatite from the Yeates prospect, Otter Lake, Quebec: evidence of marble anatexis in the central metasedimentary belt of the Grenville Province.The Canadian Mineralogist, Vol. 57, pp. 583-604.Canada, Quebeccarbonatite

Abstract: We have investigated a locality very well known to mineral collectors, the Yates U-Th prospect near Otter Lake, Québec. There, dikes of orange to pink calcite enclose euhedral prisms of fluorapatite, locally aligned. Early investigators pointed out the importance of micro-inclusions in the prisms. We describe and image the micro-inclusions in two polished sections of fluorapatite prisms, one of them with a millimetric globule of orange calcite similar to that in the matrix. We interpret the globule to have been an inclusion of melt trapped during growth. Micro-globules disseminated in the fluorapatite are interpreted to have crystallized in situ from aliquots of the boundary-layer melt enriched in constituents rejected by the fluorapatite; the micro-globules contain a complex jigsawed assemblage of carbonate, silicate, and sulfate minerals. Early minerals to crystallize are commonly partly dissolved and partly replaced by lower-temperature phases. Such jigsawed assemblages seem to be absent in the carbonate matrix sampled away from the fluorapatite prisms. The pressure and temperature attained at the Rigolet stage of the Grenville collisional orogeny were conducive to the anatexis of marble in the presence of H2O. The carbonate melt is considered to have become silicocarbonatitic by assimilation of the enclosing gneisses, which were also close to their melting point. Degassing was important, and the melt froze quickly. The evidence points to a magmatic origin for the carbonate dikes and the associated clinopyroxenite, rather than a skarn-related association.
DS2002-1378
2002
De Franco, R.Sabadini, R., Marotta, A.M., De Franco, R., Vermeersen, L.L.A.Style of density stratification in the mantle and true polar wander induced by ice loadingJournal of Geophysical Research, Oct. 29, 10.1029/2001JB000889.MantleGeophysics - seismics
DS200812-0269
2008
De Franco, R.De Franco, R., Govers, R., Wortel, R.Nature of the plate contact and subduction zones diversity.Earth and Planetary Science Letters, Vol. 271, 1-4, pp. 241-244.MantleSubduction
DS200812-0270
2008
De Franco, R.De Franco, R., Govers, R., Wortel, R.Dynamics of continental collision: influence of the plate contact.Geophysical Journal International, Vol. 174, 3, pp. 1101-1120.MantleTectonics
DS1997-0942
1997
De Freitas, E.A.Rainbird, R.H., De Freitas, E.A.Stratigraphic evidence for the Siberia Laurentia connection and early Cambrian rifting: comments/reply.Geology, Vol. 25, No. 6, June pp. 569-572.Russia, Siberia, Anabar shield, Baffin Island, Victoria IslandStratigraphy, Rifting
DS1999-0442
1999
De Freitas, S.R.C.Mantovani, M.S.M., Shukowsky, W., De Freitas, S.R.C.Tectonic pattern of South America inferred from tidal gravity anomaliesPhysical Earth and Planetary Interiors, Vol. 114, No. 1-2, July 6, pp. 91-100.South AmericaGeophysics - gravity
DS2001-0730
2001
De Freitas, S.R.C.Mantovani, M.S.M., De Freitas, S.R.C., Shukowsky, W.Tidal gravity anomalies as a tool to measure rheological properties of the continental lithosphereJournal of South American Earth Sciences, Vol. 14, No. 1, Apr. pp. 1-14.South AmericaGeophysics - gravity, Geodynamics
DS1996-0348
1996
De Freitas Suita, M.T.De Freitas Suita, M.T., Streider, A.J.chromium spinels from Brazilian mafic-ultramafic complexes: metamorphicmodifications.International Geology Review, Vol. 38, No. 3, March pp. 245-267.BrazilAlkaline rocks, Canabrava Complex
DS1996-0349
1996
De Freitas Suita, M.T.De Freitas Suita, M.T., Strieder, A.J.chromium spinels from Brazilian mafic ultramafic complexes: metamorphicmodificationInternational Geology Review, Vol. 38, No. 3, March pp. 245-267BrazilLayered intrusions, Magmatism
DS1999-0720
1999
De Freitas Suita, M.T.Strieder, A.J., De Freitas Suita, M.T.Neoproterozoic geotectonic evolution of To cantins structural province, Central Brasil.Journal of Geodynamics, Vol. 28, No. 2-3, Sept. 2, pp. 267-89.Brazil, Central BrazilTectonics
DS1996-0607
1996
De Frietas, T.Harrison, J.C., De Frietas, T.New showings and new geological settings for mineral exploration in the Arctic Islands.Geological Survey of Canada (GSC) Paper, No. 1996-B, pp. 81-91.Northwest Territories, Arctic IslandsGeology
DS1993-0334
1993
De Frietas, T.A.De Frietas, T.A., Mayr, U.Middle Paleozoic tear faulting, basin development, and basement uplift central Canadian Arctic.Canadian Journal of Earth Sciences, Vol. 30, pp. 603-20.GlobalTectonics
DS200712-0227
2007
De Frietas Macedo, M.H.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
DS1998-1591
1998
de Gasparis, S.Wood, B.D., Scott Smith, B.H., de Gasparis, S.The Mountain Lake kimberlitic pipes of northwest Alberta: exploration, geology and emplacement model.7th International Kimberlite Conference Abstract, pp. 960-62.AlbertaPetrography, model, Deposit - Mountain Lake
DS1998-0980
1998
De GasperisMcKinlay, F.T., Scott Smith, B.H., De Gasperis, KongGeology of the recently discovered Hardy Lake kimberlites, northwest Territories7th International Kimberlite Conference Abstract, pp. 564-6.Northwest TerritoriesXenocrysts, palynology, Deposit - Hardy Lake
DS1998-1639
1998
De Gasperis, A.A.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
DS200412-2099
2004
De Gironncoli, S.Wentzcovitch, R.M., Karki, B.B., Cococcioni, M., De Gironncoli, S.Thermoelastic properties of MgSiO3 perovskite: insights on nature of the Earth's lower mantle.Physical Review Letters, Vol. 92, 1. Jan. 1, Ingenta 1040799374MantlePerovskite
DS201903-0502
2019
de Godoy, D.F.da Silva, B.V., Hackspacher, P.C., Siqueira Riberio, M.C., Glasmacher, U.A., Goncalves, A.O., Doranti-Tiritan, C., de Godoy, D.F., Constantino, R.R.Evolution of the southwestern Angolan margin: episodic burial and exhumation is more realistic than long term denudation.International Journal of Earth Sciences, Vol. 108, pp. 89-113.Africa, Angolathermochronology

Abstract: There are two main points of view regarding how continental margins evolve. The first one argues that the present-day margins have been developed by long-term denudation since a major exhumation episode, probably driven by rifting or another relevant tectonic event. The second one argues that continental margins underwent alternating burial and exhumation episodes related to crustal tectonic and surface uplift and subsidence. To demonstrate that the proximal domain of the southwestern Angolan margin has evolved in a polycyclic pattern, we present a review of geological and thermochronological information and integrate it with new combined apatite fission-track and (U-Th)/He data from Early Cretaceous volcanic and Precambrian basement samples. We also provide hypotheses on the possible mechanisms able to support the vertical crustal movements of this margin segment, which are also discussed based on some modern rifting models proposed for Central South Atlantic. The central apatite fission-track ages range from 120.6?±?8.9 to 272.9?±?21.6 Ma, with the mean track lengths of approximately 12 µm. The single-grain apatite (U-Th)/He ages vary between 52.2?±?1 and 177.2?±?2.6 Ma. The integration of the thermochronological data set with published geological constraints supports the following time-temperature evolution: (1) heating since the Carboniferous-Permian, (2) cooling onset in the Early Jurassic, (3) heating onset in the Early Cretaceous, (4) cooling onset in the Mid- to Late Cretaceous, (5) heating onset in the Late Cretaceous, and (6) cooling onset in the Oligocene-Miocene. The thermochronological data and the geological constraints, support that the proximal domain of the southwestern Angolan margin was covered in the past by pre-, syn-, and post-rift sediments, which were eroded during succeeding exhumation events. For this margin segment, we show that a development based on long-term denudation is less realistic than one based on burial and exhumation episodes during the last 130 Myr.
DS1991-0354
1991
De Goutiere, A.De Goutiere, A.A diamond inclusion and dyed rubiesCanadian Gemologist, Vol. XII, No. 4, Winter p. 109GlobalDiamond inclusion, Mineralogy
DS201312-0215
2013
De Grave, J.Dobretsov, N.L., Buslov, M.M., De Grave, J., Sklyarov, E.V.Interplay of magmatism, sedimentation, and collision processes in the Siberian craton and the flanking orogens.Russian Geology and Geophysics, Vol. 54, 10, pp. 1135-1149.RussiaMagmatism
DS201412-0299
2014
De Grave, J.Glorie, S., Zhimulev, F.I., Buslov, M.M., Andersen, T., Plavsa, D., Izmer, A., Vanhaecke, F., De Grave, J.Formation of the Kokchetav subduction collision zone - northern Kazakhstan : insights from zircon U-Pb and Lu-Hf isotope systematics.Gondwana Research, Vol. 27, pp. 424-438.Russia, KazakhstanSubduction
DS201707-1301
2017
De Gregorio, B.T.Alexander, C.M.O'D., Cody, G.D., De Gregorio, B.T., Nittler, L.R., Stroud, R.M.The nature, origin and modification of insoluable organic matter in chondrites, the major source of Earth's C and N.Chemie der Erde, Vol. 77, pp. 227-256.Mantlemeteorites

Abstract: All chondrites accreted ~3.5 wt.% C in their matrices, the bulk of which was in a macromolecular solvent and acid insoluble organic material (IOM). Similar material to IOM is found in interplanetary dust particles (IDPs) and comets. The IOM accounts for almost all of the C and N in chondrites, and a significant fraction of the H. Chondrites and, to a lesser extent, comets were probably the major sources of volatiles for the Earth and the other terrestrial planets. Hence, IOM was both the major source of Earth’s volatiles and a potential source of complex prebiotic molecules. Large enrichments in D and 15N, relative to the bulk solar isotopic compositions, suggest that IOM or its precursors formed in very cold, radiation-rich environments. Whether these environments were in the interstellar medium (ISM) or the outer Solar System is unresolved. Nevertheless, the elemental and isotopic compositions and functional group chemistry of IOM provide important clues to the origin(s) of organic matter in protoplanetary disks. IOM is modified relatively easily by thermal and aqueous processes, so that it can also be used to constrain the conditions in the solar nebula prior to chondrite accretion and the conditions in the chondrite parent bodies after accretion. Here we review what is known about the abundances, compositions and physical nature of IOM in the most primitive chondrites. We also discuss how the IOM has been modified by thermal metamorphism and aqueous alteration in the chondrite parent bodies, and how these changes may be used both as petrologic indicators of the intensity of parent body processing and as tools for classification. Finally, we critically assess the various proposed mechanisms for the formation of IOM in the ISM or Solar System.
DS2003-0878
2003
De Groot, D.Martens, P., Rotmans, J., De Groot, D.Biodiversity: luxury or necessityGlobal Environmental Change, Part A, Vol. 13, 2, pp. 75-81.GlobalBiodiversity - Not specific to diamonds
DS200412-1231
2003
De Groot, D.Martens, P., Rotmans, J., De Groot, D.Biodiversity: luxury or necessity.Global Environmental Change, Part A, Vol. 13, 2, pp. 75-81.GlobalBiodiversity - Not specific to diamonds
DS1997-0258
1997
De Groot, P.De Groot, P.The uses of stable isotopes in mineral exploration: an overviewEconomic Geology Research Unit, No. IC 310, 36pGlobalBook - table of contents, Hydrothermal alteration, ore models, geochronology
DS2002-0385
2002
De Groote, E.Doblas, M., Lopez Ruiz, J., Cebria, J.M., Youbi, N., De Groote, E.Mantle insulation beneath the West African Craton during the Precambrian Cambrian transition.Geology, Vol. 30, 9, Sept. pp. 839-42.West AfricaGeothermometry
DS1995-0402
1995
De Groot-Hedlin, C.De Groot-Hedlin, C., et al.Evidence of crustal thickening beneath the northern Tien Shan Mountains from teleseismic arrivals.Eos, Vol. 76, No. 46, Nov. 7. p.F416. Abstract.ChinaCrust, Geophysics -seismic
DS200612-1466
2006
De Gryse, O.Van Royan, J., De Weedt, F., De Gryse, O.HPHT treatment of Type Ia brown diamonds.GIA Gemological Research Conference abstract volume, Held August 26-27, p. 37. 1/2p.TechnologyHPHT
DS1996-1035
1996
De Haas, G.J.L.M.Nijland, T.G., Maijer, C., De Haas, G.J.L.M.The Skokkafjell troctolite: its bearing on the early P-T evolution of the Rogaland TerraneNeues Jahrb. fur Min, Vol. 171, No. 1, pp. 91-NorwayTroctolite
DS1984-0222
1984
De haas, W.J.M.De haas, W.J.M.A Seabed Sampler for the Dredging IndustryGeodrilling, No. 26, JUNE PP. 20-24.GlobalMarine Mining Methods
DS200512-0223
2005
De Hoog, J.C.M.De Hoog, J.C.M.An empirical calibration of an Al in olivine geothermometer applicable to garnet bearing lithologies.GAC Annual Meeting Halifax May 15-19, Abstract 1p.Africa, South AfricaGeothermometry
DS200512-0224
2005
De Hoog, J.C.M.De Hoog, J.C.M.The origin of lithospheric mantle: evidence from a trace element study of eclogite and lherzolite xenoliths from Kaalvaalei Craton.GAC Annual Meeting Halifax May 15-19, Abstract 1p.Africa, South AfricaKapvaal Craton, depletion patterns, metasomatism
DS200612-1492
2006
De Hoog, J.C.M.Vrabec, M., De Hoog, J.C.M., Janak, M.Partial melting of zoisite eclogite and its significance for trace element cycling in subduction zones.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 14. abstract onlyMantleEclogite
DS200712-0226
2007
De Hoog, J.C.M.De Hoog, J.C.M., Janak, M., Vrabec, M.The role of zoisite in trace element distribution in subduction zones.Plates, Plumes, and Paradigms, 1p. abstract p. A211.Mantle, Alps, HimalayasSubduction
DS200812-0271
2008
De Hoog, J.C.M.De Hoog, J.C.M.Geochemistry of mantle olivine and application to geothermometry.Goldschmidt Conference 2008, Abstract p.A208.MantleXenoliths from kimberlites - Group II elements
DS201012-0140
2010
De Hoog, J.C.M.De Hoog, J.C.M., Gall, L., Cornell, D.H.Trace element geochemistry of mantle olivine and application to mantle petrogenesis and geothermometry.Chemical Geology, In press available formatted 20p.MantleGeobarometry
DS201212-0152
2012
De Hoog, J.C.M.De Hoog, J.C.M., Stachel, T.Trace element geochemistry of olivine inclusions in diamonds from Akwatia, Ghana: implications for diamond paragenesis and mantle processes.emc2012 @ uni-frankfurt.de, 1p. AbstractAfrica, GhanaDeposit - Akwatia
DS201912-2776
2019
de Hoog, J.C.M.de Hoog, J.C.M., Tachel, T., Harris, J.W.Trace element geochemistry of diamond hosted olivine inclusions from the Akwatia mine, West African Craton: implications for diamond paragenesis and geothermobaromtry.Contributions to Mineralogy and Petrology, Vol. 174, 28p. PdfAfrica, Ghanadeposit - Akwatia

Abstract: Trace-element concentrations in olivine and coexisting garnets included in diamonds from the Akwatia Mine (Ghana, West African Craton) were measured to show that olivine can provide similar information about equilibration temperature, diamond paragenesis and mantle processes as garnet. Trace-element systematics can be used to distinguish harzburgitic olivines from lherzolite ones: if Ca/Al ratios of olivine are below the mantle lherzolite trend (Ca/Al??300 µg/g Ca or?>?60 µg/g Na are lherzolitic. Conventional geothermobarometry indicates that Akwatia diamonds formed and resided close to a 39 mW/m2 conductive geotherm. A similar value can be derived from Al in olivine geothermometry, with TAl-ol ranging from 1020 to 1325 °C. Ni in garnet temperatures is on average somewhat higher (TNi-grt?=?1115-1335 °C) and the correlation between the two thermometers is weak, which may be not only due to the large uncertainties in the calibrations, but also due to disequilibrium between inclusions from the same diamond. Calcium in olivine should not be used as a geothermobarometer for harzburgitic olivines, and often gives unrealistic P-T estimates for lherzolitic olivine as well. Diamond-hosted olivine inclusions indicate growth in an extremely depleted (low Ti, Ca, Na, high Cr#) environment with no residual clinopyroxene. They are distinct from olivines from mantle xenoliths which show higher, more variable Ti contents and lower Cr#. Hence, most olivine inclusions in Akwatia diamonds escaped the refertilisation processes that have affected most mantle xenoliths. Lherzolitic inclusions are probably the result of refertilisation after undergoing high-degree melting first. Trivalent cations appear to behave differently in harzburgitic diamond-hosted olivine inclusions than lherzolitic inclusions and olivine from mantle xenoliths. Some divalent chromium is predicted to be present in most olivine inclusions, which may explain high concentrations up to 0.16 wt% Cr2O3 observed in some diamond inclusions. Strong heterogeneity of Cr, V and Al in several inclusions may also result in apparent high Cr contents, and is probably due to late-stage processes during exhumation. However, in general, diamond-hosted olivine inclusions have lower Cr and V than expected compared to mantle xenoliths. Reduced Na activity in depleted harzburgites limits the uptake of Cr, V and Sc via Na-M3+ exchange. In contrast, Al partitioning in harzburgites is not significantly reduced compared to lherzolites, presumably due to uptake of Al in olivine by Al-Al exchange.
DS202002-0176
2019
De Hoog, J.C.M.De Hoog, J.C.M., Stachel, T., Harris, J.W.Trace element geochemistry of diamond hosted olivine inclusions from the Akwatia mine, West African Craton: implications for diamond paragenesis and geothermobarometry.Contributions to Mineralogy and Petrology, Vol. 174, (12) doi: 10.1007/s00410-019-1634-yAfrica, Ghanadeposit - Akwatia

Abstract: Trace-element concentrations in olivine and coexisting garnets included in diamonds from the Akwatia Mine (Ghana, West African Craton) were measured to show that olivine can provide similar information about equilibration temperature, diamond paragenesis and mantle processes as garnet. Trace-element systematics can be used to distinguish harzburgitic olivines from lherzolite ones: if Ca/Al ratios of olivine are below the mantle lherzolite trend (Ca/Al??300 µg/g Ca or?>?60 µg/g Na are lherzolitic. Conventional geothermobarometry indicates that Akwatia diamonds formed and resided close to a 39 mW/m2 conductive geotherm. A similar value can be derived from Al in olivine geothermometry, with TAl-ol ranging from 1020 to 1325 °C. Ni in garnet temperatures is on average somewhat higher (TNi-grt?=?1115-1335 °C) and the correlation between the two thermometers is weak, which may be not only due to the large uncertainties in the calibrations, but also due to disequilibrium between inclusions from the same diamond. Calcium in olivine should not be used as a geothermobarometer for harzburgitic olivines, and often gives unrealistic P-T estimates for lherzolitic olivine as well. Diamond-hosted olivine inclusions indicate growth in an extremely depleted (low Ti, Ca, Na, high Cr#) environment with no residual clinopyroxene. They are distinct from olivines from mantle xenoliths which show higher, more variable Ti contents and lower Cr#. Hence, most olivine inclusions in Akwatia diamonds escaped the refertilisation processes that have affected most mantle xenoliths. Lherzolitic inclusions are probably the result of refertilisation after undergoing high-degree melting first. Trivalent cations appear to behave differently in harzburgitic diamond-hosted olivine inclusions than lherzolitic inclusions and olivine from mantle xenoliths. Some divalent chromium is predicted to be present in most olivine inclusions, which may explain high concentrations up to 0.16 wt% Cr2O3 observed in some diamond inclusions. Strong heterogeneity of Cr, V and Al in several inclusions may also result in apparent high Cr contents, and is probably due to late-stage processes during exhumation. However, in general, diamond-hosted olivine inclusions have lower Cr and V than expected compared to mantle xenoliths. Reduced Na activity in depleted harzburgites limits the uptake of Cr, V and Sc via Na-M3+ exchange. In contrast, Al partitioning in harzburgites is not significantly reduced compared to lherzolites, presumably due to uptake of Al in olivine by Al-Al exchange.
DS200612-1463
2005
De Hoop, M.V.Van der Hilst, R.D., De Hoop, M.V.Banana doughnut kernels and mantle tomography.Geophysical Journal International, Vol. 163, 3, Dec. pp. 956-961.MantleGeophysics - tomography
DS200712-0660
2007
de Hoop, M.V.Ma, P., Wang, P., Tenorio, L., de Hoop, M.V., Van der Hilst, R.D.Imaging of structure at and near the core mantle boundary using a generalized radon transform2. inference of singularities.Journal of Geophysical Research, Vol. 112, B8, B08403.MantleGeophysics - seismics
DS200812-1236
2008
De Hoop, M.V.Wang, P., De Hoop, M.V., Van der Hilst, R.D.Imaging the lowermost mantle 'D' and the core mantle boundary with SKKS coda waves.Geophysical Journal International, Vol. 175, 1, pp. 103-115.MantleBoundary
DS2001-0238
2001
De Ignacio, C.De Ignacio, C., Lopex, I., Oyarzun, MarquezThe northern Patagonia Somuncura plateau basalts: a product of slab induced shallow asthenospheric upwellTerra Nova, Vol. 13, pp. 117-21.Patagonia, South AmericaSubduction, Basalt
DS200512-0756
2005
De Ignacio, C.Munoz, M., Sagredo, J., De Ignacio, C., Fernandez-Suarez, J., Jeffries, T.E.New dat a ( U Pb K Ar ) on the geochronology of the alkaline carbonatitic association of Fuerteventura Canary Islands, Spain.Lithos, Advanced in press,Europe, Spain, Canary IslandsCarbonatite, geochronology
DS200612-0955
2005
De Ignacio, C.Munoz, M., Agredo, J., De Ignacio, C., Fernandez-Suarez, J., Jeffries, T.E.New dat a ( U Pb K Ar) on the geochronology of the alkaline carbonatitic association of Fuerteventura, Canary Islands, Spain.Lithos, Vol. 85, 1-4, Nov-Dec. pp. 140-153.Europe, SpainCarbonatite, Geochronology
DS201012-0141
2010
De Ignacio, C.De Ignacio, C., Munoz, M., Sagredo, J.Carbonatites and associated nephelinites from Sao Vicente Cape Verde Islands.International Mineralogical Association meeting August Budapest, abstract p. 552.Europe, Cape Verde IslandsCarbonatite
DS201212-0153
2012
De Ignacio, C.De Ignacio, C., Munoz, M., Sagredo, J.Carbonatites and associated nephelinites from Sao Vicente, Cape Verde Islands.Mineralogical Magazine, Vol. 76, 2, pp. 311-355.Africa, Cape Verde IslandsCarbonatite
DS201012-0142
2009
De Jong, K.De Jong, K.Apparent partial loss 40Ar 39 Ar age spectra of hornblende from the Paleoproterozic Lapland Kola orogen ( Arctic European Russia): insights into modelling ....Geosciences Journal, Vol. 13, 3, Sept. pp. 317-329.Russia, Kola PeninsulaMulti-method-in situ microsampling geochronology
DS201112-1135
2011
De Jong, M.D.Yaxley, G.M., Berry, A.J., Kamenetsky, V.S., Woodland, A.B., Paterson, D., De Jong, M.D., Howard, D.L.Redox profile through the Siberian craton: Fe K edge XANES determination of Fe3/Fe2 in garnet from peridotite xenoliths in the Udachnaya kimberlite.Goldschmidt Conference 2011, abstract p.2217.RussiaThermobarometry
DS201112-0085
2011
De Jonge, M.D.Berry, A.J., Yaxley, G.M., Hanger, B.J., Woodland, A.B., De Jonge, M.D., Howard, D.L., Paterson, D.Quantitative mapping of the oxidation state of iron in mantle garnet.Goldschmidt Conference 2011, abstract p.522.TechnologyIndicator of diamond versus carbonate stability
DS201312-0077
2013
De Jonge, M.D.Berry, A.J., Yaxley, G.M., Hanger, B.J., Woodland, A.B., De Jonge, M.D., Howard, D.L., Paterson, D., Kamenetsky, V.S.Quantitative mapping of the oxidative effects of mantle metasomatism.Geology, Vol. 41, pp. 683-686.Africa, South AfricaDeposit - Wesselton
DS200612-0320
2006
De Kamp, E.De Kamp, E.Geology of Nunavut,Geological Survey of Canada, Scale 1: 3,000,000 nunavutgeoscience.caCanada, NunavutMap - geology
DS2001-1117
2001
De KempSt.Onge, M.R., Scott, D.J., Corrigan, Wodicka, De KempThe fundamental asymmetry of a continent - continent collision zone: a Superior to Rae Craton transect.Geological Association of Canada (GAC) Annual Meeting Abstracts, Vol. 26, p. 146.abstract.Quebec, Baffin IslandTrans Hudson orogen, Tectonics
DS200612-1350
2006
De Kemp, E.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
DS201012-0125
2009
De Kemp, E.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
DS1998-1308
1998
De Kemp, E.A.Scott, D.J., De Kemp, E.A.Bedrock geology, compilation northern Baffin Island and northern MelvillePeninsula.Geological Society of Canada (GSC) Open File, No. 3633, 34, 35, 36 2 Vol. CD-ROM approx. $ 400.00Northwest Territories, Baffin IslandSurficial, mineral deposits, Metallogeny, geophysics, geochemistry
DS201412-0858
2014
de Kemp, E.A.Snyder, D.B., Hillier, M.J., Kjarsgaard, B.A., de Kemp, E.A., Craven, J.A.Lithospheric architecture of the Slave Craton, northwest Canada, as determined from an inter disciplinary 3-D model.Geochemistry, Geophysics, Geosystems: G3, Vol. 15, DOI: 10:1002/2013 GC005168Canada, Northwest TerritoriesTectonics
DS2001-0450
2001
De Kemp, et al.Harris, J.R., Eddy, B., Rencz, A., De Kemp, et al.Remote sensing as a geological mapping took in the Arctic: preliminary results from Baffin Island.Can. Geological Survey Current Research, No. 2001-E12, 22p.Northwest Territories, Nunavut, Baffin IslandRemote sensing
DS201708-1623
2017
de Klerk, W.de Klerk, W.Geochemical and petrographical study of megacrysts and mantle xenoliths from Gemsbok Hollow and Gruendorn kimberlites in the Warmbad kimberlite Province, South Africa11th. International Kimberlite Conference, PosterAfrica, South Africadeposit - Warmbad
DS1995-0403
1995
De Klerk, W.J.De Klerk, W.J.Textures exhibited by feldspars in the Giant Mottled anorthosite of the Bastard Unit, Upper Critical ZoneMineralogy and Petrology, Vol. 54, No. 1-2, pp. 25-34South AfricaAnorthosite, layered intrusion, platinum group elements (PGE), Deposit -Bushveld Complex
DS1992-0350
1992
De Kock, G.S.De Kock, G.S.Forearc basin evolution in the Pan-African Damara Belt, central Namibia:the Hureb Formation of the Khomas ZonePrecambrian Research, Vol. 57, No. 3-4, July pp. 169-194NamibiaBasin evolution, Khomas Zone
DS1998-0532
1998
De Kock, G.S.Gresse, P.G., Thomas, R.J., De Beer, C.H., De Kock, G.S.The development of the Anti Atlas Orogen, Morocco: parallels with the Pan-African belts of southern AfricaJournal of African Earth Sciences, Vol. 27, 1A, p. 92. AbstractMoroccoOrogeny
DS2002-0365
2002
De Kock, G.S.De Kock, G.S., Wolmarans, L.International tectonic map of southern Africa, Madagascar, Seychelles and oceans11th. Quadrennial Iagod Symposium And Geocongress 2002 Held Windhoek, Abstract p. 23.MadagascarTectonics
DS1930-0214
1936
De kock, W.P.De kock, W.P.Diamonds in Southwest AfricaWindhoek: Southwest Africa Mines Department, Southwest Africa, NamibiaHistory, Occurrences
DS200912-0734
2009
De Koker, N.Stixrude, L., De Koker, N., Sun, N., Mookherjee, M., Karki, B.B.Thermodynamics of silicate liquids in the deep Earth.Earth and Planetary Interiors, Vol. 278, 3-4, pp. 226-232.MantleGeothermometry
DS201012-0143
2010
De Koker, N.De Koker, N.Thermal conductivity of MgO periclase at high pressure: implications for the D' region.Earth and Planetary Science Letters, Vol. 292, 3-4, pp. 392-398.MantleUHP
DS201112-0254
2011
De Koker, N.De Koker, N., Stixrude, L., Karki, B.Melts in the deep mantle: insights from first principles molecular dynamics.Goldschmidt Conference 2011, abstract p.736.MantleThermodynamic relation for melts.
DS201112-0718
2011
De Koker, N.Naliboff, J.B., LKithgow-Bertolini, C., Ruff, L.J., De Koker, N.The effects of lithospheric thickness and density structure on Earth's stress.Geophysical Journal International, in press availableMantleDynamics - gravity, tectonics
DS201312-0198
2013
De Koker, N.De Koker, N., Karki, B.B., Stixrude, L.Thermodynmaics of the MgO-SiO2 liquid system in Earth's lowermost mantle from first principles.Earth and Planetary Science Letters, Vol. 361, pp. 58-63.MantleMelting
DS1960-0137
1961
De Kun, N.De Kun, N.Die Niobkarbonatite von AfrikaNeues Jahrb. Miner., Vol. 6, PP. 124-135.Southwest Africa, NamibiaCarbonatite, Niobium
DS1960-0536
1965
De Kun, N.De Kun, N.The Mineral Resources of AfricaNew York: Elsevier., 740P.South Africa, West Africa, Central Africa, East AfricaMineral Resources, Occurrences, Diamond, Kimberley
DS1987-0144
1987
De Kun, N.De Kun, N.Mineral economics of AfricaElsevier, 345p. gold and diamonds pp. 288-292AfricaEconomics, Many individual reference
DS2000-0941
2000
De la Cruz, R.Suarez, M., De la Cruz, R.Tectonics in the eastern central Patagonian Cordillera ( 45 30 to 47 30)Journal of Geological Society of London, Vol. 157, No. 5, Sept.pp. 995-1002.GlobalTectonics
DS1986-0840
1986
De la Nuez, J.Villaseca, C., De la Nuez, J.Camptonite dikes in the Spanish central system *SPAEstudios Geologicos (Madrid)*SPA., Vol. 42, No. 2-3, pp. 690-77GlobalBlank
DS200812-0281
2008
De la Nuez, J.Demeny, A., Casilla, R., Ahijado, A., De la Nuez, J., Milton, A.J., Nagy, G.Carbonate xenoliths in La Palma: carbonatite or alteration product?Chemie der Erde, Vol. 68, 4, pp. 369-381.Europe, SpainCarbonatite
DS201412-0710
2014
De La Pierre, M.Prencipe, M., Bruno, M., Nestola, F., De La Pierre, M., Nimis, P.Toward an accurate ab initio estimation of compressibility and thermal expansion of diamond in the (0, 3000K) temperature and (0,30 Gpa) pressure ranges, at the hybrid HF/DFT theoretical level.American Mineralogist, Vol. 99, pp. 1147-1154.TechnologyUHP
DS1990-0322
1990
de la R. Winter, H.Cheney, E.S., Roering, C., de la R. Winter, H.The Archean-Proterozoic boundary in the Kaapvaal Province of SouthernAfricaPrecambrian Research, Vol. 46, No. 4, March pp. 329-340Southern AfricaProterozoic, Petrology
DS1991-0239
1991
de la Rosa, J.D.Castro, A., Moreno-Ventas, I., de la Rosa, J.D.H-type (hybrid) granitoids: a proposed revision of the granite type classification and nomenclatureEarth Science Reviews, Vol. 31, pp. 237-253GlobalGranitoids, Classification
DS2002-1195
2002
De la Rosa, J.D.Otamendi, J.E., De la Rosa, J.D., Patino Douce, CastroRayleigh fractionation of heavy rare earths and yttrium during metamorphic garnet growth.Geology, Vol. 30, No. 2, Feb. pp.159-62.ArgentinaMetamorphism, Melting - not specific to diamonds
DS1950-0188
1954
DE LADDERSOUS, A.Moeller, DE LADDERSOUS, A.Le Diamant Au Congo BelgeBanque Centrale Du Congo Belge Bulletin., 3RD. ANNEE, No. 3, MARCH 22P.Democratic Republic of Congo, Central AfricaDiamond Mining
DS1992-1111
1992
De Laeter, J.R.Nelson, D.R., De Laeter, J.R., Fletcher, I.R.A comparative study of the geochemical and isotopic systematics of late Archean flood basalts from the Pilbara and Kaapvaal CratonsPrecambrian Research, Vol. 54, No. 2-4, January pp. 231-256Australia, South AfricaArchean, Flood basalts
DS1994-0406
1994
De Laeter, J.R.De Laeter, J.R.A question of time: Royal Society's medallist lectureJournal of Royal Soc. Western Australia, Vol. 77, No. 1, March pp. 5-14GlobalTime, Relative time
DS201512-1909
2015
De Lamotte, F.De Lamotte, F., Fourdan, D., Leleu, B., Leparmentier, S., Clarens, F.Style of rifting and the stages of Pangea.Tectonics, Vol. 34, 5, pp. 1009-1029.MantlePangea

Abstract: Pangea results from the progressive amalgamation of continental blocks achieved at 320?Ma. Assuming that the ancient concept of “active” versus “passive” rifting remains pertinent as end-members of more complex processes, we show that the progressive Pangea breakup occurred through a succession of rifting episodes characterized by different tectonic evolutions. A first episode of passive continental rifting during the Upper Carboniferous and Permian led to the formation of the Neo-Tethys Ocean. Then at the beginning of Triassic times, two short episodes of active rifting associated to the Siberian and Emeishan large igneous provinces (LIPs) failed. The true disintegration of Pangea resulted from (1) a Triassic passive rifting leading to the emplacement of the central Atlantic magmatic province (200?Ma) LIP and the subsequent opening of the central Atlantic Ocean during the lowermost Jurassic and from (2) a Lower Jurassic active rifting triggered by the Karoo-Ferrar LIP (183?Ma), which led to the opening of the West Indian Ocean. The same sequence of passive then active rifting is observed during the Lower Cretaceous with, in between, the Parana-Etendeka LIP at 135?Ma. We show that the relationships between the style of rifts and their breakdown or with the type of resulting margins (as magma poor or magma dominated) are not straightforward. Finally, we discuss the respective role of mantle global warming promoted by continental agglomeration and mantle plumes in the weakening of the continental lithosphere and their roles as rifting triggers.
DS1987-0290
1987
De Larouziere, F.D.Hernandez, J., De Larouziere, F.D., Bolze, J., Bordet, P.Neogene magmatism in the Western Mediterranean area, Southern Spain, North Africa- strike slip faulting and calc alkaline volcanism.(in French)Bulletin Soc. Geol. Fr.(in French), Vol. 3, No. 2, pp. 257-267GlobalLamproite, Shoshonite
DS1985-0142
1985
De Latit, P.De Latit, P.The Birth of Diamonds.(in French)Sciences et Avenir (in French), Vol. 457, pp. 32-37GlobalGenesis
DS1992-0803
1992
De Laurier, J.M.Jones, A.G., Gough, D.I., Kurtz, R.D., De Laurier, J.M., et al.Electromagnetic images of regional structure in the southern CanadianCordilleraGeophysical Research Letters, Vol. 12, No. 24, pp. 2373-2376Cordillera, British ColumbiaGeophysics -electromagnetic, Tectonics, structure
DS201112-0157
2011
De Lemos Peroni, R.Cerueira Koppe, V., Coimba Leite Costa, J.F., De Lemos Peroni, R., Koppe, J.C.Choosing between two kind of sampling patterns using geostatistical simulation: regularly spaced or at high uncertainty locations.Natural Resources Research, Vol. 20, 2, June pp. 131-TechnologyEconomics - not specific to diamonds
DS200612-0568
2006
De Leon, A.Hergt, J.M., De Leon, A., Woodhead, J.D.The NSW leucitites: lithospheric melts or hot spot magmas?Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 247. abstract only.Australia, New South WalesLeucitites
DS201808-1785
2018
de Leon, N.P.Rose, B.C. ,Huang, D., Zhang, Z-H., Stevenson, P., Tyryshkin, A.M., Sangtawesin, S., Srinivasan, S., Loudin, L., Markham, M.L., Edmonds, A.M., Twitchen, D.J., Lyon, S.A., de Leon, N.P.Observation of an environmentally insensitive solid-state spin defect in diamond.Science , Vol. 361, July 6, p. 60-63.Technologysynthetic

Abstract: Engineering coherent systems is a central goal of quantum science. Color centers in diamond are a promising approach, with the potential to combine the coherence of atoms with the scalability of a solid-state platform. We report a color center that shows insensitivity to environmental decoherence caused by phonons and electric field noise: the neutral charge state of silicon vacancy (SiV0). Through careful materials engineering, we achieved >80% conversion of implanted silicon to SiV0. SiV0 exhibits spin-lattice relaxation times approaching 1 minute and coherence times approaching 1 second. Its optical properties are very favorable, with ~90% of its emission into the zero-phonon line and near -transform-limited optical linewidths. These combined properties make SiV0 a promising defect for quantum network applications.
DS1989-0322
1989
de l'Etolie, R.Dagbert, M., de l'Etolie, R., McLean, P., Lane, A.SECTCAD: un programme de C.A.O. pour l'evaluation desgisements.*FRENCHThe Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Annual Meeting Preprint and Outline of slides *FRENCH, 22p. Database # 18041GlobalComputer, Program -SECTCAD.
DS2003-1530
2003
De Lian LiuYong, X., De Lian Liu, Dai, Jin-XingExtremely h2 rich fluid inclusions in eclogite from the Dabie Shan orogenic belt, EasternJournal of the Geological Society of India, Vol. 61, 1, Jan., pp. 101-102.ChinaUHP
DS1998-0320
1998
De Lima, E.F.De Lima, E.F., Naradi, L.V.S.The Lavras do Sul shoshonitic association: implications for origin and evolution of Neoproterozoic magmatismJournal of South American Earth Sciences, Vol. 11, No. 1, pp. 67-78Brazil, southernShoshonites, Magmatism
DS202002-0175
2019
de Lira Santos, L.C.M.de Araujo Neto, J.F., de Brito Barreto, S., Carrino, T.A., Muller, A., de Lira Santos, L.C.M.Mineralogical and gemological characterization of emerald crystals from Parana deposit, NE Brazil: a study of mineral chemistry, absorption and reflectance spectroscopy and thermal analysis.Brazil Journal of Geology ( www.scielo.br) ENG, 15p. PdfSouth America, Brazildeposit - Parana

Abstract: The Paraná deposit, located at Southwestern Rio Grande do Norte state, in Brazil, is one of the few emerald deposits found at Borborema Province. The mineralization occurs in phlogopite schists and actinolite-phlogopite schists associated with pegmatites and albitites within the Portalegre Shear Zone. Unlike other well-known Brazilian emerald deposits, the mineralogy of Paraná emeralds has remained poorly investigated for the last 40 years. In this study, we conducted mineralogical characterization of theses emeralds through gemological testing, mineral chemistry, absorption and reflectance spectroscopy, and thermal analysis. The Paraná emeralds are bluish-green colored, characterized by high refractive index, several two-phase fluid inclusions and mica is the main mineral inclusion. Electron probe microanalysis and laser ablation-inductively coupled plasma-mass spectrometry analyses detected the presence of Fe2+ (0.43-1.94 wt.% FeO) and Cr3+ (0.04-0.14 wt.% Cr2O3) as the main chromophores replacing octahedral Al3+ in the crystal structure. In addition, substantial amounts of MgO (0.40-2.72 wt.%), Na2O (0.50-1.81 wt.%), and Cs2O (0.07-0.44 wt.%) were also identified. The main causes for its coloration were attributed to Cr3+ absorption features in visible spectral range, which were corroborated by absorption and reflectance spectra. The presence of types I and II H2O at channel-sites was recorded in Fourier-transform infrared spectra and demonstrated by dehydration processes observed in different thermal and thermogravimetric analyses.
DS1994-0407
1994
De Los Rios Martin de Argenta, J.De Los Rios Martin de Argenta, J.Sample recovery from a kimberlite as a basis for beneficiation for diamondrecovery. *SPANISHMsc. Thesis, University Of Pellenica De Madrid, *spanish, GlobalMineral processing, Diamond beneficiation -recovery
DS201312-0744
2013
De Lourdes, M.Rio, D.C., Davis, D., Conceicao, H., De Lourdes, M., Rosa, S., Moura, C.A.V.Carbonatitic magmas? A mineralogical and isotopic approach.Goldschmidt 2013, AbstractSouth America, BrazilGeochronology
DS2003-0057
2003
De Maiffe, D.Auwera, J.V., Bogaerts, M., Liegeois, J.P., De Maiffe, D., Wilmart, E., Bolle, O.Derivation of the 1.0 0.9 Ga ferro potassic A type granitoids of southern Norway byPrecambrian Research, Vol. 124, 2-4, pp. 107-148..NorwayBlank
DS200412-0077
2003
De Maiffe, D.Auwera, J.V., Bogaerts, M., Liegeois, J.P., De Maiffe, D., Wilmart, E., Bolle, O., Duchesne, J.C.Derivation of the 1.0 0.9 Ga ferro potassic A type granitoids of southern Norway by extreme differentiation from basic magmas.Precambrian Research, Vol. 124, 2-4, pp. 107-148..Europe, NorwayAlkalic
DS1992-0351
1992
De Makos, R.M.D.De Makos, R.M.D., Brown, L.D.Deep seismic profile of the Amazonian craton (northern Brasil) #1Tectonics, Vol. 11, No. 3, June pp. 621-633BrazilGeophysics -seismics, Craton
DS202002-0177
2019
de Mamam Anzolin H.de Mamam Anzolin H., Dani, N., Remus, M.V.D., da Rocha Ribeiro, R., Nunes, A.R., Ruppel, K.M.V.Apatite multi-generations in the Tres Estradas carbonatite, southern Brazil: physical and chemistry meaning and implications to phosphate ore quality. Brazil Journal of Geology ( www.scielo.br) ENG, 17p. PdfSouth America, Brazildeposit - Tres Estradas

Abstract: Carbonatites were recently discovered in Southern Brazil, which increased the interest to evaluate the economic potential of these uncommon rocks, especially the Três Estradas Carbonatite. Carbonates are the dominant minerals of fresh rock followed by apatite, but the weathering process makes apatite abundant. We focused on apatite from the carbonatite using conventional petrography and electronic microscopy associated with microprobe, micro-Raman and Fourier-transform infrared spectroscopy. Results demonstrate the existence of four types. The primary type is associated with the rock crystallization and the subsequent three others are associated with weathering processes. The alteration mechanism was favorable for initial carbonate leaching and subsequent increase of phosphate with late precipitation of three new apatite generations. The deduced model involves long exposure during polycyclic climate changes, intercalating periods of warm dry with humid climate. The apatite types differ chemically and morphologically and have distinctive characteristics that are suitable to be used to differentiate them. These properties should be considered in future planes of industrial processes to transform apatite into single superphosphate, a basic input for fertilizer production.
DS201112-0255
2010
De Mattos Coelho, F.De Mattos Coelho, F., Svisero, D.P., Filho, W.F.Geologia e mineralogia da min a de diamantes de Romaria, Min as Gerais.5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 50-51.South America, Brazil, Minas GeraisOverview of area
DS201802-0230
2018
de Medeiros, S.G.De Carvallo, L.D.V., Schnellrath, J., de Medeiros, S.G.Mineral inclusions in diamonds from Chapada Diamantina, Bahia, Brazil: a raman spectroscopic characterization, REM ****IN PORTInternational Engineering Journal, Ouro Preto *** IN: PORT, Vol. 71, 1, pp. 27-35.South America, Brazildeposit - Chapada

Abstract: The Chapada Diamantina, located in the central region of the State of Bahia, is of important historical significance due to its diamond occurrences. Discovered in the nineteenth century, comprehensive research about the regional diamonds and their origins are still limited, demanding more investigation in the matter. Looking for insights about their genesis, mineral inclusions in 23 alluvial diamonds from 4 garimpos located in the Chapada Diamantina were analyzed through the use of Raman micro spectroscopy. Additionally, the characteristics of nitrogen aggregation of the host diamonds were measured using Fourier-transform infrared spectroscopy (FTIR). The diamonds from Chapada Diamantina consist mainly of well-formed crystals, with dominant dodecahedral habits, characterized by faint to very light yellow body colors, typically with green and brown radiation spots on their surface. The main surface textures observed are related to processes that took place in the late stage resorption and during the residence of the diamonds in placer environments. The diamonds are predominantly type IaAB, with a significant occurrence of poorly aggregated nitrogen (Type IaA diamond). The main mineral assemblages of the studied peridotitic inclusions refer to a harzburgitic paragenesis.
DS1994-0408
1994
De Medeiros Delgado, I.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
DS1994-0409
1994
De Medeiros Delgado, I.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
DS2002-0366
2002
De Meer, S.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
DS2002-0367
2002
De Meer, S.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
DS2003-0324
2003
De Meer, S.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
DS1997-0259
1997
De Meijer, R.J.De Meijer, R.J., Stapel, C., Jones, D.G., Roberts..Improved and new uses of natural radiactivity n mineral exploration andprocessingExploration and Mining Geology, Vol. 6, No. 1, pp. 105-117GlobalCoast - sediments, heavy minerals, Technology - radioactivity
DS200812-0272
2008
De Meijer, R.J.De Meijer, R.J., Van Westrenen, W.The feasibility and implications of nuclear georeactors in Earth's core-mantle boundary region.South African Journal of Science, Vol. 104, 3/4, pp. 111-118.MantleBoundary
DS1998-0321
1998
De Meillon, L.De Meillon, L., Bristow, J.W.Some characteristics of high level Tertiary age alluvial terraces along the Orange River ..7th International Kimberlite Conference Abstract, pp. 193-4.South Africa, Northern Cape ProvinceAlluvials, Deposit - Douglas area
DS201412-0073
2014
De Meillon, L.Bristow, J.W., De Meillon, L.The Middle Orange River diamond sink.GSSA Kimberley Diamond Symposium and Trade Show provisional programme, Sept. 11, title onlyAfrica, South AfricaMiddle Orange River
DS201412-0175
2014
De Meillon, L.De Meillon, L.A diamond is not a pig - target selection and diamond trap site identification along the Middle Orange River between Hopetown and Douglas.GSSA Kimberley Diamond Symposium and Trade Show provisional programme, Sept. 11, title onlyAfrica, South AfricaMiddle Orange River
DS201607-1342
2016
De Meillon, L.De Meillon, L.The Orange and Riet River alluvial diamond deposits in the vicinity of Douglas, Northern Cape Province: geology, evaluation, and exploitation of unique South African large diamond producing deposits.IGC 35th., Session Mineral Exploration 1p. AbstractAfrica, South AfricaAlluvials, diamonds
DS201911-2519
2019
de Meillon, L.de Meillon, L.The alluvial deposits of the Middle Orange River. Paleostone Miningwww.gssa.org Deposits of the Northern Cape , Oct. 10-11, 1p. AbstractAfrica, South Africaalluvials
DS200612-0209
2006
De Mets, C.Calasi, E., Han, J.Y., De Mets, C., Nocquet, J.M.Deformation of the North American plate interior from a decade of continuous GPS measurements.Journal of Geophysical Research, Vol. 111, B6, B06301.Canada, United StatesGeophysics - seismics
DS200812-0273
2008
De Mets, C.De Mets, C.Tectonics: Arabia's slow dance with India.Nature Geoscience, Vol. 1, 1, pp. 10-11.IndiaTectonics
DS200712-0912
2007
De Min, A.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
DS200912-0123
2009
De Min, A.Comin-Chiaramonti, P., Lucassen, P., Girardi, V.A.V., De Min, A., Gomes, C.B.Lavas and their mantle xenoliths from intracratonic eastern Paraguay( South American Platform) and Andean domain NW Argentina: a comparative review.Mineralogy and Petrology, in press availableSouth America, Paraguay, ArgentinaXenoliths
DS201012-0116
2009
De Min, A.Comin-Chiaramonti, P., Lucassen, F., Girardi, V.A.V., De Min, A., Gomes, C.B.Lavas and their mantle xenoliths from intracratonic Eastern Paraguay ( South American Platform) and Anean Domain, NW Argentina: a comparative review.Mineralogy and Petrology, Vol. 98, 1-4, pp. 143-165.South America, Paraguay, ArgentinaXenoliths
DS201112-0884
2011
De Min, A.Ruberti, E., Enrich, G.E.R., Azzone, R.G., Comin-Chiaramonti, P., De Min, A., Gomes, C.B.The Banhadao alkaline complex, southeastern Brazil: source and evolution of potassic SiO2 undersaturated high Ca and low Ca magmatic series.Mineralogy and Petrology, In press available,South America, BrazilAlkalic
DS201212-0605
2012
De Min, A.Ruberti, E., Enrich, G.E.R., Azzone, R.G., Comin-Chiaramonti, P., De Min, A., Gomes, C.B.The Banhadao alkaline complex, southeastern Brazil: source and evolution of potassic SiO2 undersaturated high Ca and low Ca magmatic series.Mineralogy and Petrology, Vol. 104, 1-2, pp. 63-80.South America, BrazilAlkalic
DS201312-0199
2013
De Min, A.De Min, A., Hendriks, B., Siejko, F., Comin-Chiaramonti, P., Girardi, V., Ruberti, E., Gomes, C.B., Neder, R.D., Pinho, F.C.Age of ultramafic high K rocks from Planalto da Serra ( Mato Grosso, Brazil).Journal of South American Earth Sciences, Vol. 41, pp. 57-64.South America, BrazilGeochronology
DS201504-0191
2015
De Min, A.Comin-Chiaramonti, P., Gomes, C.B., De Min, A., Ernesto, M., Gasparon, M.Magmatism along the high Paraguay River at the border of Brazil and Paraguay: a review and new constraints on emplacement ages.Journal of South American Earth Sciences, Vol. 58, March pp. 72-81.South America, Paraguay, BrazilGeochronology

Abstract: The magmatic rocks from Alto Paraguay (High Paraguay River extensional lineament), western Apa craton, mainly consist of several major circular alkaline complexes and some rhyolitic domes and ignimbrites. The former are characterized by intrusive Na-alkaline rock-types (nepheline syenites and syenites and effusive equivalents) topped by lava flows and ignimbrites. Two main evolved suites were defined using petrochemical and Sr- isotope data: an agpaitic suite in the north and a miaskitic suite in the south. The domes of subalkaline rhyolitic lavas and ignimbrites occur to the north of the alkaline complexes, along the Paraguay River, near the town of Fuerte Olimpo. The emplacement ages of the alkaline complexes were constrained using the K-Ar, Ar-Ar, Rb-Sr and Sm-Nd dating methods on whole rocks and/or mineral separates (amphibole, alkali feldspar and biotite). Ages are quite variable (Upper Permian to Middle Triassic), with average K-Ar and Ar-Ar ages of 248.8 ± 4.8 and 241.8 ± 1.1 Ma, respectively, and Rb-Sr and Sm-Nd age data giving best values from 248 ± 4 to 244 ± 27 Ma and from 256 ± 3 to 257 ± 3 Ma, respectively. In contrast, the Fuerte Olimpo volcanics show a Mesoproterozoic age (1.3 Ga, K-Ar and Ar-Ar radiometric methods; and 1.42 ± 0.24 to 1.30 ± 0.03 Ga, Rb-Sr and Sm-Nd methods, respectively). Rb-Sr systematics (87Sr/86Sr initial ratios = 0.7038) highlight a relatively "primitive" character of the Na-alkaline magmatic source(s), in contrast with the "crustal" values (87Sr/86Sr initial ratio ~ 0.7105) of the Fuerte Olimpo rhyolites. Thus, magmatism in the Alto Paraguay area is related to two extensional events: a younger event corresponding to the Permian-Triassic alkaline rocks, and an older event connected to the Precambrian volcanic acidic rocks.
DS201609-1712
2016
De Min, A.Comin-Chiaramonti, P., Renzulli, A., Ridolfi, F., Enrich, G.E.R., Gomes, C.B., De Min, A., Azzone, R.G., Ruberti, E.Late stage magmatic to deuteric metasomatic accessory minerals from the Cerro Boggiani agpaitic complex ( Alto Paraguay alkaline province.Journal of South American Earth Sciences, Vol. 71, pp. 248-261.South America, ParaguayCarbonatite

Abstract: This work describes rare accessory minerals in volcanic and subvolcanic silica-undersaturated peralkaline and agpaitic rocks from the Permo-Triassic Cerro Boggiani complex (Eastern Paraguay) in the Alto Paraguay Alkaline Province. These accessory phases consist of various minerals including Th-U oxides/silicates, Nb-oxide, REE-Sr-Ba bearing carbonates-fluorcarbonates-phosphates-silicates and Zr-Na rich silicates. They form a late-stage magmatic to deuteric/metasomatic assemblage in agpaitic nepheline syenites and phonolite dykes/lava flows made of sodalite, analcime, albite, fluorite, calcite, ilmenite-pyrophanite, titanite and zircon. It is inferred that carbonatitic fluids rich in F, Na and REE percolated into the subvolcanic system and metasomatically interacted with the Cerro Boggiani peralkaline and agpaitic silicate melts at the thermal boundary layers of the magma chamber, during and shortly after their late-stage magmatic crystallization and hydrothermal deuteric alteration.
DS201611-2128
2016
De Min, A.Omarini, R.H., Gasparon, M., De Min, A., Comin-Chiaramonti, P.An overview of the Mesozoic-Cenozoic magmatism and tectonics in Eastern Paraguay and central Andes ( Western Gondwana): implications for the composition of mantle sources.Journal of South American Earth Sciences, Vol. 72, pp. 302-314.South America, ParaguayMagmatism

Abstract: The amalgamation of the Western Gondwana (including the Greater Gondwana supercraton) occurred at 600 Ma during the Brazilian - Pan African orogeny. A plate junction related to this event is marked by the Transbrazilian lineament which separates the South American continent into two sectors: the Eastern Paraguay-Brazilian and Central Andean domains. An overview of the geodynamic data from these two sectors indicates that the two domains were subjected to distinct evolutions from the Proterozoic to the present. The Andean domain is characterized by long-lived subduction processes linked to the convergence and consequent collision of microplates since the Middle Proterozoic (western Amazonian Craton) with a peak at about 600-580 Ma. The Paraguay-Brazilian domain remained relatively stable but was affected by extension episodes that reactivated ancient (Early and Middle Proterozoic) suture zones. These different geodynamic evolutions seem to reflect broadly distinct mantle compositions. In the subduction zones of the Andean domain the mantle was deeply modified by metasomatic processes following the subduction of oceanic plates. Consequently, the Andean type magma sources show a clear HIMU imprint inherited from the MORB, whereas the Paraguay-Brazilian sector shows a prevalent EMI and subordinate EMII character. The petrological data mainly from Mesozoic and Cenozoic magmatic events in the two sectors are reviewed to investigate the current mantle plume and mantle dome models for the uprising of the asthenospheric (or sub-lithospheric) material.
DS201702-0199
2016
De Min, A.Castillo Clerici, A.M., Gomes, C.B., De Min, A., Comin-Chiaramonti, P.Heavy minerals in the sediments from Paraguay rivers as indicators for diamond occurrences. IN Port**Boletin del Museo Nacional de Historia Narural del Paraguay, Vol. 20, 2, pp. 188-204. pdf available in * PortSouth America, ParaguayGeochemistry - indicator minerals

Abstract: Many diamondiferous kimberlites in the Lac de Gras region of the Northwest Territories are concealed by glacial drift, rendering them challenging to detect by traditional exploration techniques that exploit residual surface chemistry. Much research has been aimed at the development of deep penetrating geochemical exploration technologies to increase the rate of discovery whilst reducing risk and exploration cost. However, results from a detailed study of soil geochemistry above the DO-18 kimberlite (Peregrine Diamonds) demonstrate the potential to apply conventional surface geochemical techniques coupled with surface material mapping and landscape evolution models to the evaluation of discrete targets. 50 soil samples from the oxidized upper B-horizon in a detailed grid crossing the concealed kimberlite were collected. Samples, screened to -180 microns, were analysed by multi-element ICP-MS following 4-acid, aqua-regia and deionized water extractions. Fp-XRF was utilised as an equivalent total method to evaluate its applicability. Sequential leach on selected samples was undertaken to understand the deportment of the elements of interest within the soils. Surficial mapping included soil type, topographic variation, landforms, environment and vegetation. This allows an assessment of surface controls on the geochemistry, in particular the generation of false anomalies from chemical traps such as swamps; and allows the generation of a landscape development model. Hydrocarbons, analysed using the SGH and Gore-sorber techniques, were evaluated to characterize the type and abundance of complex hydrocarbons above the kimberlite relative to above the host granitic gneiss. Geochemical data is subject to landform generation processes. The northern half of the grid comprises till with numerous frost boils. The southern half, at lower topography below a distinct break, is dominated by sand-rich material and fine clay. Results from the 4-acid and aqua regia extraction show a dispersion of Nb, Ni, Mg, Ce, Cr and Cs from directly above the northern part of the kimberlite to the edge of the sampling grid, approximately 500 metres to the northwest, following glacial dispersion. SGH-hydrocarbon results exhibit a similar pattern in light-alkyl benzenes. Fp-XRF data repeats the pattern in all elements except Mg, where the concentrations are too low for reliable detection. In the southern half of the grid, at a lower topographic level, geochemical responses are considerably more subtle. It is hypothesised that anomaly formation in the till followed standard glacial dispersion in the down ice trend. Material was entrained to the surface from deeper in the till, locally above the kimberlite, by frost boil action. The southern part of the area is considered to have been inundated with water, the remains of which comprise the current lake over the DO-27 kimberlite approximately 400m to the south. Sediments in this area are clay rich - comprising material deposited by the lake, or re-worked sandy material along the palaeo-lake margin and subsequent erosional channels. These later processes acted to further disperse, conceal and dilute the signal of the underlying body.
DS202011-2034
2016
De Min, A.Castillo Clerici, A.M., Gomes, C.B., De Min, A., Comin-Chiaramonti, P.Heavy minerals in the sediments from Paraguay rivers as indicators for diamonds occurrences. *** NOTE DATEBol. Mus. Nac. Hist. Parag. *** ENG, Vol. 20, 2, pp. 188-204. pdfSouth America, Paraguaygeochemistry

Abstract: After some works of Jaime Baez-Presse that quoted the presence of diamonds in Eastern Paraguay, we have perfprmed a whole sampling a study relative to the indicator mineral for diamonds. Indicator minerals are mineral species that, when appearing as transported grains in clastic sediments, indicate the presence in bedrock of a specific type of mineralization, hydrothermal alteration or lithology. Their physical and chemical characteristics, including a relatively high density (heavy minerals), facilitate their preservation and identification. The heavy minerals represent an important exploration method for detecting a variety of ore deposit types including diamond, gold, Ni-Cu, PGE, and so on.. One of the most significant events in the application of indicator mineral methods in the past was the diamond exploration. This paper provides an overview of indicator mineral methods, i.e. presence of Cr-diopside, Pyrope-rich garnet and Picroilmenite, for diamond exploration along the Eastern Paraguay river. Unfortunately the above heavy mineraks, generally associated to the diamonds, do not appear in Eastern Paraguay, excluding this Country as a potential source for the diamond as economic potential source.
DS201609-1735
2016
De Min, A.M.Omarini, R.H., Gasparon, M., De Min, A.M., Comin-Chiaramonti, P.An overview of the Mesozoic-Cenozoic magmatism and tectonics of Eastern Paraguay and central Andes ( western Gondwana): implications for the composition of mantle sources.Journal of South American Earth Sciences, In press available, 19p.South America, ParaguayMagmatism
DS1994-0410
1994
De Miranda, F.P.De Miranda, F.P., MCCafferty, A.E., Taranik, J.V.Reconnaissance geologic mapping of portion of rain forest covered Guianashield, using SIR-B, digital dataGeophysics, Vol. 59, No. 5, May pp. 733-742BrazilGeophysics -aeromagnetics, SIR-B.
DS201512-1907
2015
De Montgolfier, J.D'Arpizio, C., Levato, F., Zito, D., De Montgolfier, J.Luxury goods worldwide market study Fall-Winter 2014.Bain & Company, Nov. 5, 38p. PdfGlobalDiamond market
DS1960-0031
1960
De Montmorency, A.De Montmorency, A.Soviets Enter World Diamond MarketSunday Star, Washington., JANUARY 31RussiaDiamonds Notable
DS201906-1271
2019
de Moor, J.M.Barry, P.H., de Moor, J.M., Giovannelli, D., Schrenk, M., Hummer, D.R., Lopez, T., Pratt, C.A., Alpizar Segua, Y., Battaglia, A., Beaudry, A., Bini, G., Cascante, M., d'Errico, G., di Carlo, M., Fattorini, D., Fullerton, K., H+Gazel, E., Gonzalez, G., HalForearc carbon sink reduces long term volatile recycling into the mantle.Nature , 588, 7753, p. 487.Mantlecarbon

Abstract: Carbon and other volatiles in the form of gases, fluids or mineral phases are transported from Earth’s surface into the mantle at convergent margins, where the oceanic crust subducts beneath the continental crust. The efficiency of this transfer has profound implications for the nature and scale of geochemical heterogeneities in Earth’s deep mantle and shallow crustal reservoirs, as well as Earth’s oxidation state. However, the proportions of volatiles released from the forearc and backarc are not well constrained compared to fluxes from the volcanic arc front. Here we use helium and carbon isotope data from deeply sourced springs along two cross-arc transects to show that about 91 per cent of carbon released from the slab and mantle beneath the Costa Rican forearc is sequestered within the crust by calcite deposition. Around an additional three per cent is incorporated into the biomass through microbial chemolithoautotrophy, whereby microbes assimilate inorganic carbon into biomass. We estimate that between 1.2 × 108 and 1.3 × 1010 moles of carbon dioxide per year are released from the slab beneath the forearc, and thus up to about 19 per cent less carbon is being transferred into Earth’s deep mantle than previously estimated.
DS201312-0200
2013
De Moor, M.De Moor, M., Fischer, T.P., King, P.L., Botcharnikov, R.E., Hervig, R.L., Hilton, D.R., Barry, P.H., Mangasini, F., Ramirez, C.Volatile rich silicate melts from Oldoinyo Lengai volcano (Tanzania): implications for carbonatite genesis and eruptive behavior.Earth and Planetary Science Letters, Vol. 361, pp. 379-390.Africa, TanzaniaDeposit - Oldoinyo Lengai
DS201112-0122
2011
de Moortele, B.V.Bruno, R., Kenji, M., de Moortele, B.V.Electrical conductivity of the serpentinized mantle and fluid flow in subduction zones.Earth and Planetary Science Letters, Vol. 307, 3-4, pp. 387-394.MantleGeophysics - seismics
DS201312-0741
2013
de Mora, J.Reolid, M., Sacchez-Gomez, M., Abad, I., Gomez-Sanchez, M.E., de Mora, J.Natural monument of the Volcano of Cancarix, Spain: a case of lamproite phreatomagmatic volcanism.Geoheritage, Vol. 5, 1, pp. 35-45.Europe, SpainLamproite
DS1987-0671
1987
De Mulder, M.Shieh, Y.N., De Mulder, M.Oxygen and strontium isotope constraints on the origin of the Karisimbipotassic lava series, Virunga East African rift valleyGeological Society of America, Vol. 19, No. 7 annual meeting abstracts, p.842. abstracEast AfricaBasanite
DS200512-0376
2005
De Natale, G.Gudmundsson, A., Acocella, V., De Natale, G.The tectonics and physics of volcanoes.Journal of Volcanology and Geothermal Research, Vol. 144, 1-4, pp. 1-5.MantleVolcanoes
DS201709-2043
2017
de Oliveira, A.B.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.
DS200512-0225
2005
De Oliveira, C.A.De Oliveira, C.A., Neves, J.M.Magmatism, rifting and sedimentation related to Late Paleoproterozoic mantle plume events of central and southeastern Brazil.Journal of Geodynamics, Vol. 39, 3, pp. 197-208.South America, BrazilMagmatism, hotspots
DS200812-0334
2008
De Oliveira, D.P.S.Ezzouhari, H., Ribeiro, M.L., AitAyad, N., Moreira, M.E., Charif, A., Ramos, J.M.F., De Oliveira, D.P.S., Coke, C.The magmatic evolution at the Moroccan outboard of the West African Craton between the Late Neoproterozoic and the Early Palaeozoic.Special Publication - Geological Society of London, No. 297, pp. 329-344.Africa, MoroccoMagmatism
DS201702-0209
2017
De Oliveira, I.L.De Oliveira, I.L., Brod, J.A., Cordeiro, P.F.O., Dantas, E.L., Mancini, L.H.Insights into the Late stage differentiation processes of the Cat alao I Carbonatite complex in Brazil: new Sr-Nd and C-O isotopic dat a in minerals from niobium ores.Lithos, In press available, 44p.South America, BrazilDeposit - Catalao I

Abstract: The Late Cretaceous Catalão I carbonatite complex consists of ultramafic silicate rocks, phoscorites, nelsonites and carbonatites. The latest stages of the evolution of the complex are characterized by several nelsonite (magnetite-apatite rock) and carbonatite dykes, plugs and veins crosscutting earlier alkaline rocks. The interaction between the latter and late-stage carbonatites and/or carbo-hydrothermal fluids, converted the original dunites and bebedourites to metasomatic phlogopitites. Late-stage nelsonites (N1), pseudonelsonites (N2) and various types of dolomite carbonatites (DC) including norsethite-, magnesite- and/or monazite-bearing varieties show significant whole-rock Nd and Sr isotopic variations. To elucidate whether magmatic or metasomatic processes, or both, were responsible for these isotope variations we characterized the Nd and Sr isotope compositions of major mineral phases (i.e. apatite, dolomite, norsethite, pyrochlore and tetraferriphlogopite) in these late-stage rocks. Mineral isotope data recorded the same differences observed between N1 and N2 whole-rocks with N2 minerals showing more enriched isotopic signatures than minerals from N1. Sr isotopic disequilibrium among minerals from N2 pseudonelsonites and spatially related dolomite carbonatite pockets implies formation from batches of carbonate melts with distinct isotopic compositions. A detailed investigation of Nd and Sr isotopes from whole-rocks and minerals suggests that the most evolved rocks of the Catalão I complex probably derive from two different evolution paths. We propose that an earlier magmatic trend (path A) could be explained by several batches of immiscible and/or residual melts derived from carbonated-silicate parental magma (e.g. phlogopite picrite) contaminated with continental crust to a variable extent, in an AFCLI-like process. A second trend (path B) comprises highly variable 143Nd/144Ndi at nearly constant 87Sr/86Sri coupled with high d18O in carbonates. This is interpreted here as the result of the interaction of previously-formed dolomite carbonatites with carbo-hydrothermal fluids.
DS1990-0987
1990
De Oliveira, J.J.Marker, A., De Oliveira, J.J.The formation of rare earth element scavenger minerals in weathering products derived from alkaline rocks of southeast-Bahia, BrasilChemical Geology ( Geochem. of the Earth's surface and of min. formation, 2nd., Vol. 84, No. 1-4, July 5, pp. 373-374. AbstractBrazilAlkaline rocks, rare earth elements (REE).
DS1994-1106
1994
De Oliveira, J.J.Marker, A., De Oliveira, J.J.Climatic and morphological control of rare earth element distribution inweathering mantles on alkaline rocks.Catena, Special issue Laterization Processes, Vol. 21, No. 2-3, pp. 179-194.BrazilAlkaline rocks, Rare earths, Weathering, Laterization
DS201602-0228
2015
de Oliveira, R.G.Neto, I.C., Cunha, L.M., Silveira, F.V., Nannini, F., de Oliveira, R.G., deSouza, W.S., Bezerra, A.K.Discovery and confirmation of the first kimberlitic intrusion in the Bororema Province, NE Brazil.CPRM, Informe Technico in Port ( abstract in english), No. 2, Nov. 7p.South America, BrazilDeposit - Santa Fe-1,2
DS1998-0322
1998
De Oliveira, S.M.B.De Oliveira, S.M.B., Imbernon, R.A.L.Weathering alteration and related rare earth elements (REE) concentration in the Catalao Icarbonatite complex, central Brasil.Journal of South American Earth Sci., Vol. 11, No. 4, pp. 379-388.BrazilCarbonatite, Alteration, rare earth elements (REE).
DS1990-0395
1990
De Oliveira Castro, L.De Oliveira Castro, L.Origins of the Brazilian diamondsBrazilian Congress of Geology, 36th. Annals, Natal, Vol. 3, pp. 1331-1341BrazilHistory, Diamonds
DS202012-2211
2020
de Oliveira Chaves, A.de Oliveira Chaves, A., Porcher, C.C.Petrology, geochemistry and Sm-Nd systematics of the Paleoproterozoic Itagurra retroeclogite from Sao Francisco/Congo craton: one of the oldest records of the modern-style plate tectonics.Gondwana Research, Vol. 87, pp. 224-237. pdfSouth America, Brazileclogites
DS201112-0256
2011
De Oliveira CordeiroDe Oliveira Cordeiro, Brod, Palmieri, Gouveia de Oliveira, Soares Rocha Barbosa, Santos, Gaspar, AssisThe Catalao I niobium deposit, central Brazil: resources, geology and pyrochlore chemistry.Ore Geology Reviews, Vol. 41, pp. 112-121.South America, BrazilCarbonatite
DS201012-0144
2010
De Oliveira Cordeiro, P.F.De Oliveira Cordeiro, P.F., Brod, J.A., Ventura Santos, R., Dantas, E.L., Gouvieia de Oliveira, C., Soares Rocha, Barbosa, E.Stable ( C,O) and radiogenic (Sr, Nd) isotopes of carbonates as indicators of magmatic and post magmatic processes of phoscorite series rocks and carbonatites fContributions to Mineralogy and Petrology, In press available, 14p.South America, BrazilCatalao I
DS201212-0681
2012
De Oliveira Cordeiro, P.F.Soares Rocha Barbosa, E., Brod, J.A., Junqueira-Brod, T.C., Dantas, E.L., De Oliveira Cordeiro, P.F., Siqueira Gomide, C.Bebdourite from its type area Sailtre 1 complex: a key petrogenetic series in the Late-Cretaceous Alto Paranaiba kamafugite carbonatite phoscorite association, central Brazil.Lithos, Vol. 146-147, pp. 56-72.South America, BrazilCarbonatite
DS202002-0217
2019
de Oliveira. C.G.Santos Santiago, J., da Silva Souza, V., Dantas, E.L., de Oliveira. C.G.Ediacaran emerald mineralization in northeastern Brazil: the case of the Fazenda Bonfim deposit.Brazil Journal of Geology ( www.scielo.br) ENG, 14p. PdfSouth America, Brazildeposit - Fazenda Bonfim

Abstract: The Fazenda Bonfim emerald deposit lies within the Seridó Belt. It is a classic example of deposit formed through metasomatic interactions between Be-rich granite intrusions and Cr(± V)-rich mafic-ultramafic rocks. The setting of the emerald mineralization was built under strong strike-slip dynamics, which produced serpentinization and talcification of mafic-ultramafic host-rocks, and was followed by syn-kinematic emplacement of Be-rich albite granite, favoring hydrothermal/metasomatic processes. The structural control and lithological-contrast were fundamental to the fluid flow and the best ore-shoot geometry, developed in the S-foliation intra-plane at the contact zone (phlogopite hornfels) between mafic-ultramafic rocks and the albite granite. Subsequently, an albitization process, linked to the final-stage of magmatic crystallization, led to an overall mineralogical and chemical change of the albite granite. 207U-235Pb data revealed inheritance ages from Archean to Neoproterozoic and a crystallization age of 561 ± 4 Ma for albite granite. However, 40Ar/39Ar data revealed plateau age of 553 ± 4 Ma for phlogopite hornfels, interpreted as the closure time for the metasomatic event responsible for the nucleation and growth of emerald crystals. The short interval of time between U-Pb and Ar-Ar data indicates an intense, but not protracted, metasomatic history, probably due to low volume of intrusive magma.
DS201112-0257
2011
De Oliveire Cordeiro, P.F.De Oliveire Cordeiro, P.F., Brod, J.A., Ventura Santos, R., Dantas, E.L., Gouveia de Oliveira, C., Soares Rochas Barbosa, E.Stable (C,O) and radiogenic (Sr,Nd) isotopes of carbonates as indicators of magmatic and post-magmatic processes of phoscorite series rocks and carbonatites from Catalao 1, central Brazil.Contributions to Mineralogy and Petrology, Vol. 161, 3, pp. 451-464.South America, BrazilCarbonatite
DS1994-1107
1994
de Oliviera, J.J.Marker, A., de Oliviera, J.J., Schellmann, W.Lithodependence of partly transported weathering horizons above a migmatite diabase contact in Central Bahia State, BrasilCatena, Laterization and Supergene Ore, Vol. 21, No. 2-3, pp. 215-227BrazilDiabase dike, Laterization
DS201909-2068
2019
de Padua, M.B.Padilha, A.L., Vitorello, I., de Padua, M.B., Fuck, R.A.Magnetotelluric images of PaleoProterozoic accretion and Mesoproterozoic to Neoproterozoic reworking processes in the northern Sao Francico craton, central-eastern Brazil.Precambrian Research, in press available, 55p. pdfSouth America, Brazilcraton

Abstract: Broadband and long period magnetotelluric (MT) data were collected along an east-west oriented, 580-km-long profile across the northern São Francisco Craton where extensive Proterozoic and Phanerozoic sedimentary cover and lack of deep-probing geophysical surveys have prevented to establish unequivocally the cratonic character of the Archean-Paleoproterozoic lithosphere. Following dimensionality analyses, the MT dataset was interpreted using both 2-D and 3-D inversion procedures. The near-surface structure is better resolved in the 2-D model due to its finer resolution. A huge upper crustal conductor is found all along the shallow early Neoproterozoic Irecê Basin in the central domain of the craton, extending laterally for approximately 150?km and restricting signal propagation below the basin. Its high conductance is explained by a combination of high porosity and high fluid salinity in the sedimentary package. Another upper crustal conductor is observed on the west side of the profile, interpreted as fractured metasedimentary rocks of the Rio Preto belt thrusted on top of the craton basement during Neoproterozoic marginal collision. The 3-D model explains significantly better the measured data related to deep structure. Contrary to what is expected for a stable cratonic block, the geoelectric model shows pronounced electrical complexity and heterogeneity, an indication that the cratonic lithosphere was multiply reworked in the past by tectonothermal events. Different lithospheric resistive blocks bounded by major conductive zones are identified. Constrained by geochemical and isotopic data, these vertical conductive interfaces are interpreted as cryptic suture zones due to large-scale amalgamation of continents and microcontinents leading to the assembly of the São Francisco Craton in the Paleoproterozoic. The conductivity enhancement is more likely explained by emplacement of sulfides along previous suture zones during mafic magmatism. At upper mantle depths, high conductivity observed below most of the profile indicates that metasomatism or refertilization processes with incompatible elements caused by the Paleoproterozoic subducting slabs and Mesoproterozoic to Neoproterozoic upwelling of deep fluids and melts reworked this portion of the craton mantle.
DS1998-0318
1998
De PaepeDe Corte, K., Cartigny, P., Shatsky, De Paepe, SobolevMicrodiamonds from ultra high pressure (UHP) metamorphic rocks of Kokchetav Massif, northernKazakstan: FTIR spectroscopy....7th International Kimberlite Conference Abstract, pp. 184-186.Russia, KazakhstanMetamorphic rocks, diamond morphology, Deposit - Kokchetav
DS1989-1179
1989
De Paepe, P.Pasteels, P., Villeneuve, M., De Paepe, P., Klerkx, J.Timing of volcanism of the southern Kivu province:implications for the evolution of the western branch of the East African Rift systemEarth and Planetary Science Letters, Vol. 94, No. 3/4 September pp.353-363East AfricaTectonics, Rift
DS201904-0727
2019
De Paepe, P.Decree, S., Demaiffe, D., Tack, L., Nimpagaritse, G., De Paepe, P., Bouvais, P., Debaille, V.The Neoproterozoic Upper Ruvubu alkaline plutonic complex ( Burundi) revisited: large scale syntectonic emplacement, magmatic differentiation and late stage circulations of fluids.Precambrian Research, Vol. 325, pp. 150-171.Africa, Burundicarbonatite

Abstract: The Upper Ruvubu Alkaline Plutonic Complex (URAPC) in Burundi consists of three separate intrusions, each with a specific emplacement age and petrological composition. Three main units are recognized: an outer unit with silica-saturated plutonic rocks (from gabbro to granite), an inner unit with silica-undersaturated plutonic rocks (feldspathoidal syenite with subordinate feldspathoidal monzonite and ijolite) and a carbonatitic body in the subsoil, known by drilling. The URAPC is quite large in size (~24?km long and up to 10?km wide). It is considered to have been intruded syntectonically in an overall extensional context, thanks to the kilometric shear zones that accommodated its emplacement. Radiometric ages from literature range from 748 to 705?Ma and point to structurally-controlled magmatic differentiation followed by long-lived circulations of late-stage fluids postdating the emplacement of a part of the undersaturated rocks and the carbonatites. In the north-western part of the outer unit, gabbro likely has been emplaced at a deeper structural level than the granite, which represents a more apical structural level of emplacement. This petrological, geochemical and isotopic (Sr-Nd-Hf) study concentrates on the processes that generated the URAPC: (i) fractional crystallization, evidenced by the chemical evolution trends of the major and trace elements, and by marked P, Ti and Ba anomalies in the trace element patterns; (ii) crustal assimilation/contamination, as shown by the wide range of Nd isotope compositions and the general increase of the Sr isotope ratios with increasing SiO2 contents, and (iii) late-magmatic/hydrothermal alteration inducing an increase of the Sr isotope composition without changing significantly the Nd isotope composition. The isotopic data are consistent with an asthenospheric mantle source, though less depleted than the Depleted Mantle (DM), contaminated by the Subcontinental Lithospheric Mantle (SCLM). The silicate and carbonate magmatic series are cogenetic. The outer unit is clearly more contaminated than the inner unit, whereas the carbonatitic body could have evolved by liquid immiscibility. The URAPC lies within East Africa’s Western Rift Valley, which is marked by 23 alkaline plutonic complexes. Their emplacement has been ascribed to reactivation of Proterozoic lithospheric weakness zones resulting from the breakup of the Neoproterozoic supercontinent Rodinia supercontinent.
DS1998-1146
1998
De PaoliPeirce, 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
DS1998-0097
1998
De Paoli, G.Bedarski, J., Leckie, D., De Paoli, G.Gold recovery and kimberlite/diamond indicators from de Bonita Upland, Alberta.Geological Survey of Canada Open File, No. 3601, 7p. $ 10.50AlbertaGeochemistry, Mineralogy - indicators
DS1998-0100
1998
De Paoli, G.Bednarski, J., Leckie, D., De Paoli, G.Gold recovery and kimberlite diamond indicators from Cripple Creek, Rocky Mountain Foothills, Alberta.Geological Survey of Canada (GSC) Open File, No. 3602, p. 6.AlbertaGeochemistry
DS1998-0101
1998
De Paoli, G.Bednarski, J., Leckie, D., De Paoli, G.Gold recovery and kimberlite diamond indicators from Del Bonita Upland, Alberta.Geological Survey of Canada (GSC) Open File, No. 3602, p. 8.AlbertaGeochemistry
DS1998-0842
1998
De Paoli, G.Leckie, D., Bednarski, J., De Paoli, G.Gold recovery and kimberlite/diamond indicators from Rocky MountainFoothills, Alberta.Geological Survey of Canada Open File, No. 3602, 6p. $ 10.50AlbertaGeochemistry, Mineralogy - indicators
DS1998-0843
1998
De Paoli, G.Leckie, D.A., Bednarski, J., De Paoli, G.A report on gold recovery and kimberlite/ diamond indicators from a stream sample in the S. Rocky Mtns.Calgary Mining Forum, Apr. 8-9, p. 57. poster abstractAlbertaGeochemistry - heavy minerals
DS202001-0040
2019
De Paoli, M.C.Smithies, R.H., Lu, Y., Johnson, T.E., Kirkland, C.L., Cassidy, K.F., Champion, D.C., Mole, D.R., Zibra, I., Gessner, K., Sapkota, J., De Paoli, M.C., Poujol, M.No evidence for high pressure melting of Earth's crust in the Archean.Nature Communicatons, Vol. 10, 555912p. PdfAustraliamelting

Abstract: Much of the present-day volume of Earth’s continental crust had formed by the end of the Archean Eon, 2.5 billion years ago, through the conversion of basaltic (mafic) crust into sodic granite of tonalite, trondhjemite and granodiorite (TTG) composition. Distinctive chemical signatures in a small proportion of these rocks, the so-called high-pressure TTG, are interpreted to indicate partial melting of hydrated crust at pressures above 1.5?GPa (>50?km depth), pressures typically not reached in post-Archean continental crust. These interpretations significantly influence views on early crustal evolution and the onset of plate tectonics. Here we show that high-pressure TTG did not form through melting of crust, but through fractionation of melts derived from metasomatically enriched lithospheric mantle. Although the remaining, and dominant, group of Archean TTG did form through melting of hydrated mafic crust, there is no evidence that this occurred at depths significantly greater than the ~40?km average thickness of modern continental crust.
DS1995-1061
1995
De Paolo, D.J.Lassiter, J.C., De Paolo, D.J., Mahoney, J.J.Geochemistry of Wrangellia flood basalt province: implications for the roleof continental lithosphere.Journal of Petrology, Vol. 96, No. 4, pp. 983-1009United States, Wrangellia TerraneBasalt, Flood basalt genesis
DS1998-0323
1998
De Paolo, D.J.De Paolo, D.J., Daley, E.E.Isotopic evidence for nonuniform thinning of lithospheric mantle during continental extension.Mineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 364-5.MantleBasalts - Basin and Range
DS2000-0214
2000
De Paolo, D.J.De Paolo, D.J., Daley, E.E.Neodynium isotopes in basalts of the southwest basin and range and lithospheric thinning .. cont. extensionChemical Geology, Vol. 169, No. 3-4, Sept. pp. 157-186.Colorado PlateauGeochronology, Continent - extension
DS2003-0325
2003
De Paolo, D.J.De Paolo, D.J., Manga, M.Deep origin of hotspots - the mantle plume modelScience, Vol. 300, 5621, May 9, p. 920.MantleSubduction, Hotspot
DS2003-0401
2003
De Paolo, D.J.Feineman, M.D., De Paolo, D.J.Steady state 226 Ra 230 Th disequilibrium in mantle minerals: implications for meltEarth and Planetary Science Letters, Vol. 215, 3-4, pp. 339-55.MantleMelting, geochronology
DS200412-0426
2003
De Paolo, D.J.De Paolo, D.J., Manga, M.Deep origin of hotspots - the mantle plume model.Science, Vol. 300, 5621, May 9, p. 920.MantleSubduction
DS200412-0543
2003
De Paolo, D.J.Feineman, M.D., De Paolo, D.J.Steady state 226 Ra 230 Th disequilibrium in mantle minerals: implications for melt transport rates in island arcs.Earth and Planetary Science Letters, Vol. 215, 3-4, pp. 339-55.MantleMelting, geochronology
DS1996-1527
1996
De Paolo D.J.Wendlandt, E., De Paolo D.J., Baldridge, W.S.Thermal history of Colorado Plateau lithosphere from samarium-neodymium (Sm-Nd) mineral geochronology of xenoliths.Geological Society of America (GSA) Bulletin., Vol. 108, No. 7, July pp. 757-767.ColoradoGeochronology, Xenoliths
DS1991-0942
1991
De Paor, D.G.Kusky, T.M., De Paor, D.G.Deformed sedimentary fabrics in metamorphic rocks: evidence from the Point Lake area, Slave Province, Northwest TerritoriesGeological Society of America (GSA) Bulletin, Vol. 103, No. 4, April pp. 486-503Northwest TerritoriesStructure -fabrics, Point Lake area
DS1994-0411
1994
De Paor, D.G.De Paor, D.G.The role of asymmetry in the formation of structuresJournal of Structural Geology, Vol. 16, No. 4, pp. 467-476GlobalStructure, Asymmetry role
DS1996-0350
1996
De Paor, D.G.De Paor, D.G.Structural geology and personal computersPergamon, Elsevier, approx. $ 50.00 United StatesGlobalBook - Table of contents, Computers - structural geology, applied technology
DS201709-1962
2017
De Parseval, P.Borisova, A.Y., Zagrtdenov, N.R., Toplis, M.J., Bohrson, W.A., Nedelec, A., Safonov, O.G., Pokrovski, G.S., Ceileneer, G., Melnik, O.E., Bychkov, A.Y., Gurenko, A.A., Shscheka, S., Terehin, A., Polukeev, V.M., Varlamov, D.A., Gouy, S., De Parseval, P.Making Earth's continental crust from serpentinite and basalt. Goldschmidt Conference, abstract 1p.Mantleperidotites

Abstract: How the Earth's continental crust was formed in the Hadean eon is a subject of considerable debates [1-4]. For example, shallow hydrous peridotites [2,5], in particular the Hadean Earth's serpentinites [6], are potentially important ingredients in the creation of the continental ptoto-crust, but the mechanisms of this formation remain elusive. In this work, experiments to explore serpentinite-basalt interaction under conditions of the Hadean Earth were conducted. Kinetic runs lasting 0.5 to 48 hours at 0.2 to 1.0 GPa and 1250 to 1300°C reveal dehydration of serpentinite and release of a Si-Al-Na-K-rich aqueous fluid. For the first time, generation of heterogeneous hydrous silicic melts (56 to 67 wt% SiO2) in response to the fluid-assisted fertilisation and the subsequent partial melting of the dehydrated serpentinite has been discovered. The melts produced at 0.2 GPa have compositions similar to those of the bulk continental crust [2,3]. These new findings imply that the Earth's sialic proto-crust may be generated via fluid-assisted melting of serpentinized peridotite at shallow depths (=7 km) that do not require plate subduction during the Hadean eon. Shallow serpentinite dehydration and melting may be the principal physico-chemical processes affecting the earliest lithosphere. Making Earth's continental crust from serpentinite and basalt.
DS201412-0724
2013
De Parseval, Ph.Rasoamalala, V., Salvi, S., Bexiat, D., Ursule, J-Ph., Cuney, M., De Parseval, Ph., Guillaume, D., Moine, B., Andriamampihantona, J.Geology of bastnaesite and monazite deposits in the Ambatofinandrahana area, central part of Madagascar: an overview.Journal of African Earth Sciences, Vol. 94, 14p.Africa, MadagascarBastanesite
DS1998-0324
1998
De Pinho, I.De Pinho, I., da Silva Filho, A.F.neodymium and Strontium isotopic and uranium-lead (U-Pb) geochronologic constraints for evolution of the shoshonitic Brasiliana Bom JardiM.International Geology Review, Vol. 40, No. 6, June pp. 500-527.Brazil, BorboremaTectonics, geochronology, Transamazonia enriched mantle
DS201212-0154
2012
De Plaen, R.S.M.De Plaen, R.S.M., Bastow, I.D.Mantle seismic anisotropy in Cameroon: implications for the break up of Gondwana and the development of the Cameroon Volcanic Line.Geochemistry, Geophysics, Geosystems: G3, in preparationAfrica, CameroonGeophysics - seismics
DS1989-0341
1989
De Pretto, R.De Pretto, R.Method and trace elements for monitoring the seperation of diamonds And diamond containing particles from gangue particles on the basis of RamanscatteringPatent: De Beers Ind. Diamond Division, Title cont'd.Laser radiation, British U.K.No. 2210686 A1, June 14, 1989. 9pGlobalDiamond recovery
DS201902-0261
2019
de Roever, E.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.
DS201812-2833
2016
de Roever, E.W.F.Kroonenberg, S.B., de Roever, E.W.F., Fraga, L.M., Faraco, T., Lafon, J-M., Cordani, U., Wong, T.E.Paleoproterzoic evolution of the Guiana Shield in Suriname: a revised model.Netherlands Journal of Geolsciences, Vol. 95, 4, pp. 491-522.South America, SurinameGuiana shield

Abstract: The Proterozoic basement of Suriname consists of a greenstone-tonalite-trondhjemite-granodiorite belt in the northeast of the country, two high-grade belts in the northwest and southwest, respectively, and a large granitoid-felsic volcanic terrain in the central part of the country, punctuated by numerous gabbroic intrusions. The basement is overlain by the subhorizontal Proterozoic Roraima sandstone formation and transected by two Proterozoic and one Jurassic dolerite dyke swarms. Late Proterozoic mylonitisation affected large parts of the basement. Almost 50 new U-Pb and Pb-Pb zircon ages and geochemical data have been obtained in Suriname, and much new data are also available from the neighbouring countries. This has led to a considerable revision of the geological evolution of the basement. The main orogenic event is the Trans-Amazonian Orogeny, resulting from southwards subduction and later collision between the Guiana Shield and the West African Craton. The first phase, between 2.18 and 2.09 Ga, shows ocean floor magmatism, volcanic arc development, sedimentation, metamorphism, anatexis and plutonism in the Marowijne Greenstone Belt and the adjacent older granites and gneisses. The second phase encompasses the evolution of the Bakhuis Granulite Belt and Coeroeni Gneiss Belt through rift-type basin formation, volcanism, sedimentation and, between 2.07 and 2.05 Ga, high-grade metamorphism. The third phase, between 1.99 and 1.95 Ga, is characterised by renewed high-grade metamorphism in the Bakhuis and Coeroeni belts along an anticlockwise cooling path, and ignimbritic volcanism and extensive and varied intrusive magmatism in the western half of the country. An alternative scenario is also discussed, implying an origin of the Coeroeni Gneiss Belt as an active continental margin, recording northwards subduction and finally collision between a magmatic arc in the south and an older northern continent. The Grenvillian collision between Laurentia and Amazonia around 1.2-1.0 Ga caused widespread mylonitisation and mica age resetting in the basement.
DS2001-1188
2001
De RondeVan Roermund, H.L., Drury, M.R., Barnhoorn, De RondeRelict majoritic garnet microstructures from ultra deep peridotites in western Norway.Journal of Petrology, Vol. 42, No. 1, Jan. pp. 117-58.NorwayPeridotites, Petrology
DS1994-0412
1994
De Ronde, C.E.J.De Ronde, C.E.J., De Wit, M.Tectonic history of the Barberton greenstone belt, South Africa: 490 myears of Archean crustal evolution.Tectonics, Vol. 13, No. 4, Aug. pp. 983-1005.South AfricaArchean, Crust - evolution tectonics
DS1994-0413
1994
De Ronde, C.E.J.De Ronde, C.E.J., de Wit, M.J.Tectonic history of the Barberton greenstone belt: 490 million years of Archean crustal evolutionTectonics, Vol. 13, No. 4, August pp. 983-1005South AfricaTectonics, Barberton greenstone belt
DS200812-0274
2007
De Rosemond, S.De Rosemond, S., Irving, E., Liber, K.Benthic invertebrate colonization of kimberlite tailings from the Ekati diamond mine.Canadian Technical Report of Fisheries and Aquatic Sciences, No. 2746, p.27, Ingenta art1075288601Canada, Northwest TerritoriesDeposit - Ekati environmental
DS1991-0311
1991
De Sa, E.F.J.Corsini, M., Vauchez, A., Archanjo, C., De Sa, E.F.J.Strain transfer at continental scale from a transcurrent shear zone to a transpressional fold belt: the Patos-Serido system, northeastern BrasilGeology, Vol. 19, No. 6, June pp. 586-589BrazilStructure -shear zone, Brasiliano-pan-African Orogeny
DS200512-0442
2005
De Sa, E.F.J.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
DS201112-0081
2010
de Sa Carneiro Chaves, M.L.Benitez, L., Cookenboo, H.O., de Sa Carneiro Chaves, M.L.Macro characteristics of diamonds from different regions of the Minas Gerais and Bahia states, Brazil.5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 36-37.South America, Brazil, Minas Gerais, BahiaDiamond morphology
DS201112-0082
2010
de Sa Carneiro Chaves, M.L.Benitez, L., de Sa Carneiro Chaves, M.L.Provincias diamantiferas de Minas Gerais: caracterizacao de suas populacoes de diamantes.5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 48-49.South America, Brazil, Minas GeraisOverview of areas
DS201112-0258
2010
De Sa Carneiro Chaves, M.L.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
DS201112-0259
2010
de Sa Carneiro Chaves, M.L.de Sa Carneiro Chaves, M.L., Wanderson Andrade, K., Borges, F.M.Preservando a pedra rica (Grao Mogol, MG): primeira jazida de diamante minerada em rocha no mundo.5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 25-26.South America, Brazil, Minas GeraisBrief - history
DS201603-0364
2011
de Sa Carneiro Chaves, M.L.Andrade, K.W., de Sa Carneiro Chaves, M.L.Geologia e mineralogia do kimberlito Grota do Cedro ( Coromandel, MG).Geonomos *** IN POR, Vol. 19, 1, pp. 39-45. *** In PortugueseSouth America, BrazilDeposit - Coromandel area

Abstract: Hundreds of kimberlite intrusions and related rocks are known in the Coromandel region (MG), in the "Alto Paranaiba Diamondiferous Province", although the knowledge of these rocks is still scarce. Among these intrusions, it emphasizes the Grota do Cedro kimberlite, which outcrops in the drainage of same name at south of Coromandel (MG), hosted in micaschists of the Araxá Group (Neoproterozoic). The body has a roughly elliptical surface shape with 350 and 300 m axis; its chemical composition is similar to others of the province, and mineral chemistry of Cr-pyrope shows a strong concentration in the "G9" and "G5" fields. These chemical fields generally characterize diamond-poor or infertile intrusions.
DS201603-0372
2014
de Sa Carneiro Chaves, M.L.Deus Borges, L.A., de Sa Carneiro Chaves, M.L., Karfunkel, J.Diamonds from Borrachudo River, Sao Francisco basin ( Tiros, MG): morphologic and dissolution aspects.REM: Revista Escola de Minas, Vol. 67, 2, pp. 159-165. *** in PortugueseSouth America, BrazilAlluvials, diamonds

Abstract: A representative set of diamonds from the Borrachudo River (114 stones) was described for the first time as to their physical characteristics, among them weight, morphology, dissolution figures, and abrasion. Most samples are low in weight (~51% less than 0.30 ct) and only ~3.5% are above 3.0 ct. However, considering the total weight, ~47% of it is concentrated in the range above 3 ct. On the other hand, there even occur diamonds with dozen of carats. The most common crystallographic forms are originated from the octahedral form by dissolution, although irregular shapes like chips and flats also occur. The diamonds show differences in form compared to their weight ranges; those up to 0.30 ct have various shapes; in the range of 0.31 to 1 ct the most common are octahedral forms and their descendants; and in stones larger than 1 ct chips and flats predominate. The general habitus of the crystals, identified by their final tetrahexahedroid shapes, chips and flats, corroborated by the dissolution figures, indicate that the diamond were submitted to strong dissolution in a magmatic environment. Residual hillocks and holes represent the final stage of dissolution. The study indicates that the abrasion by the fluvial transport was not expressive enough to cause mechanical wear, thus ca. 97% shows no sign of wear. This fact suggests a proximal source for most of these diamonds.
DS200512-1094
2005
De Schrijver, I.Tomlinson, E., De Schrijver, I., De Corte, K., Jones, A.P., Moens, L., Vanhaecke, F.Trace element compositions of submicroscopic inclusions in coated diamond: a tool for understanding diamond petrogenesis.Geochimica et Cosmochimica Acta, Vol. 69, 19, Oct. 1, pp. 4719-4732.Africa, Democratic Republic of CongoSilicate melt inclusions, Group 1, diamond inclusions
DS1985-0143
1985
De sena sobrinho, M.De sena sobrinho, M.Notes on Diamond Bearing Alluvium in Minas Gerais, Brasil.(in Portugese)Iheringia Ser. Geologia, (in Portugese)., Vol. 10, pp. 3-18BrazilProspecting Methods, Sopa Formation
DS2000-0215
2000
De Sigoyer, J.De Sigoyer, J., Chavagnac, Blichert-Toft, Villa, LuaisDating the Indian continental subduction and collisional thickening in northwest Himalaya: eclogitesGeology, Vol. 28, No. 6, June pp. 487-90.IndiaSubduction - multichronology, Geochronology - Tso Morari eclogites
DS2001-0705
2001
De Sigoyer, J.Luais, B., Duchene, S., De Sigoyer, J.Sm Nd disequilibrium in high pressure, low temperature Himalayan and Alpine rocksTectonophysics, Vol. 342, No. 1-2, Dec. pp. 1-22.AlpsGeochronology, UHP - high pressure
DS1997-0183
1997
De Silva, F.C. AlvesChavet, A., De Silva, F.C. Alves, Guerrot, C.Structural evolution of the Paleoproterozoic Rio Itapicuru granite greenstone belt, Role of synkinematicPrecambrian Research, Vol. 84, No. 3-4, Oct. pp. 139-162Brazil, BahiaTectonics - regional, Rio Itapicuru Belt
DS1989-0342
1989
De Silva, S.L.De Silva, S.L.Atiplano-Puna volcanic complex of the Central AndesGeology, Vol. 17, No. 12, December pp. 1102-1106Andes, Peru, Bolivia, Chile, ArgentinaVolcanics, Tectonics
DS1991-0355
1991
De Silva, S.L.De Silva, S.L.Volcanoes of the central AndesSpringer Verlag, 232p. $ approx. 95.00AndesBook-ad, Volcanoes
DS1991-0356
1991
De Silva, S.L.De Silva, S.L., Francis, P.W.Volcanoes of the central Andes.Section of the book -large silicic systemsxeroxed. Not well in black and white as the photographs are in colour in thebookSpringer-Verlag, pp. 158-178Andes, ChileVolcanoes, Silicia systems
DS1992-0339
1992
De Silva, S.L.Davidson, J.P., De Silva, S.L.Volcanic rocks from the Bolivian Altiplano: insights into crustalstructure, contamination, and magma genesis in the central AndesGeology, Vol. 20, No. 12, December pp. 1127-1130BoliviaStructure, Volcanics
DS1995-0389
1995
De Silva, S.L.Davidson, J.P., De Silva, S.L.Late Cenozoic magmatism of the Bolivian AltiplanoCont. Min. Petrol, Vol. 119, pp. 387-408BoliviaMagmatism
DS1995-0404
1995
De Silva, S.L.De Silva, S.L., Woolff, J.A.Zoned magma chambers: the influence of magma chamber geometry on sidewall convective fractionationJournal of Vol. Geothermal Research, Vol. 65, pp. 111-118GlobalZonation, Chamber shape
DS200712-0044
2007
De Silva, S.L.Bachmann, O., Miller, C.F., De Silva, S.L.The volcanic plutonic connection as a stage for understanding crustal magmatism.Journal of Volcanology and Geothermal Research, Vol. 167, 1-4, pp. 1-23.MantleMagmatism - not specific to diamonds
DS201212-0260
2012
De Silva, S.L.Gregg, P.M., De Silva, S.L., Grosfils, E.B., Parmigiani, J.P.Catastrophic caldera forming eruptions: thermomechanics and implications for eruption triggering and maximum caldera dimensions on Earth.Journal of Volcanology and Geothermal Research, Vol. 242-242, pp. 1-12.MantleCalderas
DS2000-0216
2000
De Smet, J.De Smet, J., Van den Berg, A.P., Vlaar, N.J.Early formation and long term stability of continents resulting from decompression melting convecting mantle.Tectonophysics, Vol. 322, No. 1-2, pp. 19-33.MantleMagmatism - convection
DS2000-0217
2000
De Smet, J.De Smet, J., Van den Berg, A.P., Vlaar, N.J.Early formation and long term stability of continents resulting decompression melting in convecting mantle.Tectonophysics, Vol.322, No.1-2, July10, pp.19-34.MantleMagmatism, Convection
DS1998-0325
1998
De Smet, J.H.De Smet, J.H., Van den Berg, A.P., Vlaar, N.J.Stability and growth of continental shields in mantle convection models including recurrent melt production.Tectonophysics, Vol. 296, No. 1-2, . Oct. 30, pp. 15-30.MantleCraton, Magmatism
DS1999-0161
1999
De Smet, J.H.De Smet, J.H., Van Den Berg, A.P., Vlaar, N.J.The evolution of continental roots in numerical thermo-chemical mantle convection models including ...Lithos, Vol. 48, No. 1-4, Sept. pp. 153-70.MantleGeothermometry - model, Melting - differentiation of partial
DS1990-1334
1990
de Smeth, J.B.Sengupta, S., Ray, K.K., Acharyya, S.K., de Smeth, J.B.Nature of ophiolite occurrences along the eastern margin of the Indian plate and their tectonicsignificanceGeology, Vol. 18, No. 5, May pp. 439-442IndiaOphiolites, Tectonics
DS201212-0155
2012
De Sousa, H.A.F.De Sousa, H.A.F., Fedikow, M.A.F., Ryder, J., Turner, N., Halliday, M.Application of weak leaches in kimberlite exploration.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractCanada, OntarioGeochemistry
DS201412-0176
2014
De Sousa, M.M.De Sousa, M.M.Geologia dos depositos secundarios de diamante em Roraima.6 Simposio Brasileiro de Geologia do Diamante, Aug. 3-7, 4p. AbstractSouth America, BrazilDeposit - Dachine
DS201812-2800
2018
de Sousa do Amaral Miranda, N.de Sousa do Amaral Miranda, N.Modernization introduced by the Kimberley Process Certification.7th Symposio Brasileiro de Geologia do Diamante , Title only South America, BrazilKP
DS1950-0380
1958
De sousa machado, F.J.De sousa machado, F.J.The Volcanic Belt of Angola and Its CarbonatitesComm. Tech. Coop. African South of The Sahara Reg. Comm. Geo, No. 44, PP. 309-317.AngolaGeology, Related Rocks
DS201112-0375
2010
De Sousa Rosa, A.Goes Passos, Jr.G., De Sousa Rosa, A.Perfil do diamante no estado de Mato Grosso.5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 30-31.South America, Brazil, Mato GrossoJuina, Paraguai, Paranatinga, Rio das Mortes
DS200412-0019
2002
De Souza, A.M.P.D.Allaoua Saadi, M.N., Machette,K.M., Haller,K.M., Dart, R.L., Bradley, L-A., De Souza, A.M.P.D.Map and database of Quaternary faults and lineaments in Brazil.U.S. Geological Survey, OF 02-0230 58p $ 76.South America, BrazilMap - structure
DS200512-0226
2004
De Souza, H.De Souza, H.Use of MMI geochemistry to detect kimberlites under glacial cover.32nd Yellowknife Geoscience Forum, Nov. 16-18, p.21. (talk)Geochemistry - Mobile Metal Ion
DS1991-0357
1991
De Souza, J.L.De Souza, J.L.Crustal and upper mantle structures of the Brazilian coastPure and Applied Geophysics, Vol. 136, No. 2/3, pp. 245-264BrazilAtlantic shield, Tectonics, Geophysics -mantle
DS200712-0227
2007
De Souza, Z.S.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
DS1986-0172
1986
De St. Jorre, L.De St. Jorre, L.Economic mineralogy of the North T zone, Thor Lake NorthwestSOURCE[ MSc. Thesis, University of AlbertaMsc. Thesis, University Of Alberta, 250pNorthwest TerritoriesAlkaline rocks, Rare Earths
DS200512-0565
2005
De Stefano, A.Kopylova, M.G., Lefebvre, N.S., De Stefano, A., Kivi, K.Archean lamprophyric rocks of Wawa: diamonds in a convergent margin.GAC Annual Meeting Halifax May 15-19, Abstract 1p.Canada, Ontario, WawaAlkaline rocks, subduction, breccia, cathodluminescence
DS200612-0321
2006
De Stefano, A.De Stefano, A., Lefebvre, N., Kopylova, M.Enigmatic diamonds in Archean calc-alkaline lamprophyres of Wawa, southern Ontario, Canada.Contributions to Mineralogy and Petrology, Vol. 151, 2, pp. 158-173.Canada, Ontario, WawaGeochemistry, FTIR spectroscopy, mineral inclusions
DS200712-0228
2007
De Stefano, A.De Stefano, A., Kopylova, M.G.Growth history of Jericho diamonds: evidence from CL imagery and mineral inclusions.Geological Association of Canada, Gac-Mac Yellowknife 2007, May 23-25, Volume 32, 1 pg. abstract p.20-21.Canada, NunavutJericho diamond inclusions
DS200912-0163
2009
De Stefano, A.De Stefano, A., Kopylova, M.C., Cartigny, P., Afanasiev, V.Diamonds and eclogites of the Jericho kimberlite ( Northern Canada).Contributions to Mineralogy and Petrology, Vol. 158, 3, Sept. pp. 295-315.Canada, NunavutDeposit - Jericho
DS200912-0403
2009
De Stefano, A.Kopylova, M.G., De Stefano, A.Magnesian eclogite as a source for websteritic diamonds.GAC/MAC/AGU Meeting held May 23-27 Toronto, Abstract onlyCanada, NunavutDeposit - Jericho
DS201112-0260
2011
De Stefano, A.De Stefano, A.Diamonds in cratonic and orogenic settings: a study of Jericho and Wawa diamonds.University of British Columbia, Phd Thesis, 180p.Canada, Nunavut, Ontario, WawaThesis - note availability based on request via author
DS201212-0517
2012
DE Stefano, A.Nestola, F., Merli, M., Nimis, P., Parisatto, M., Kopylova, M., DE Stefano, A., Longo, M., Ziberna, L., Manghnani, M.In situ analysis of garnet inclusion in diamond using single crystal X-ray diffraction and X-ray micro-tomography.European Journal of Mineralogy, Vol. 24, 4, pp. 599-606.TechnologyTomography
DS201906-1331
2019
de Stefano, A.Niyazova, S., Kopylova, M., de Stefano, A.Metamorphism and metasomatism of felsic xenoliths in kimberlitesGAC/MAC annual Meeting, 1p. Abstract p. 151.Canada, Quebecdeposit - Renard 65

Abstract: Kimberlites often entrain crustal felsic xenoliths, which show alteration and metamorphism as a result of interaction with the host kimberlite. We studied granite and gneiss xenoliths in the Renard 65 kimberlite pipe (Northern Québec, Canada). The study comprised a detailed petrographic examination of 45 thin sections, a scanning electron microscopy and an X-ray powder diffractometry of a sample sub-set. Two major units of the Renard 65 pipe (Unit A and Unit B/D) distinguished by abundance of crustal xenoliths along with the degree of their alteration, were investigated. Unit A is a volcaniclastic kimberlite with 40-90 % xenoliths, whereas Unit B/D is a hypabyssal kimberlite with textures transitional to pyroclastic, containing 15-40 % more intensely altered xenoliths. Both units carry xenoliths of coarse-grained leucogranite (K-feldspar, plagioclase, quartz, biotite with accessory garnet, apatite, and zircon) and medium-grained gneiss (plagioclase, quartz, biotite, orthopyroxene with accessory garnet, apatite and zircon). The Unit A xenoliths are partially replaced by chlorite, sericite, epidote, serpentine, richterite, actinolite and clinochlore vermiculite. In Unit B/D four distinct metamorphic and metasomatic mineral assemblages almost completely replace xenoliths. The assemblages include aegirine, pectolite, garnet, wollastonite, xonotlite, prehnite, calcite, K-feldspar and richterite in various proportions. Secondary K-feldspar and calcite may indicate the granite protolith, whereas wollastonite may be the signature of the gneiss protolith. The presence of secondary garnet and wollastonite, the hallmark skarn minerals, suggests the analogy between the classical skarn geological processes at the contact between felsic rocks and the host hot carbonate-rich melts. The observed mineralogy of the Renard 65 felsic xenoliths will be compared with the theoretically predicted mineralogy modelled using Theriak-Domino or Perplex software for the known bulk hybrid kimberlite compositions. The comparison will enable constraints on temperatures, volatile contents and thermal history of the kimberlite melt during emplacement.
DS1998-0326
1998
De Suman, K.De Suman, K., Chacko, T., Creaser, R.A., MuehlenbachsGeochemical and isotopic study of granites from Taltson Magmatic zone: implications Early Proterzoic tectonicsGeological Society of America (GSA) Annual Meeting, Vol. 30, No. 7, p. 159.abstract.AlbertaOrogeny - Laurentia, Tectonics
DS2000-0218
2000
De Suman, K.De Suman, K., Chacko, T., Creaser, R.A., Muehlenbachs, K.Geochemical and neodymium lead O isotope systematics of granites Taltson magmatic zone, implications for Proterozoic ...Precambrian Research, Vol. 102, No. 3-4, pp. 221-49.AlbertaOrogeny - Laurentia, Tectonics
DS200412-0427
2004
De Toledo, M.C.M.De Toledo, M.C.M., Lenharo, S.L.R., Ferrari, V.C., Fontan, F., Parseval, P.De, Leroy, G.The compositional evolution of apatite in the weathering profile of the Catalao 1 alkaline carbonatitic complex, Goias, Brazil.Canadian Mineralogist, Vol. 42, 4, August, pp. 1139-1158.South America, Brazil, GoiasCarbonatite, geomorphology
DS1997-0201
1997
De ToniColletta, B., Roure, F., De Toni, Loureir, D., PassalacquaTectonic inheritance, crustal architecture, and contrasting structural styles in the Venezuelan AndesTectonics, Vol. 16, No. 5, Oct. pp. 777-794Andes, VenezuelaMaracaibo Basin, Tectonics, Neogene transpressional, paleozoic, Jurassic
DS1993-0335
1993
De Toni, B.De Toni, B., Kellogg, J.Seismic evidence for blind thrusting of the northwestern flank of the Venezuelan AndesTectonics, Vol. 12, No. 6, December pp. 1393-1409VenezuelaGeophysics -seismics, foredeep basin, Andes
DS1996-0351
1996
De Urreiztieta, M.De Urreiztieta, M., Gapais, D., Rossello, E.Cenozoic dextral transpression and basin development at the southern edge of the Puna PlateauTectonophysics, Vol. 254, No. 1-2, March 30, pp. 17-40ArgentinaTectonics, Puna Plateau
DS1960-0138
1961
De Villiers, J.De Villiers, J.The Gariep SystemComm. Tech. Coop. In Africa South of The Sahara., Vol. 80, PP. 87-89.Southwest Africa, NamibiaRegional Geology
DS201711-2509
2017
De Villiers, J.P.R.De Villiers, J.P.R.How to sustain mineral resources: beneficiation and mineral engineering opportunities.Elements, Vol. 13, pp. 307-312.Globalresources, CSR

Abstract: The sustainability of a mineral resource depends, among other aspects, on what the mineral in question will be used for, price fluctuations, future resource requirements, and downstream manufacturing. A balance must be struck between the long-term commitment of developing a mineral deposit against the short-term threats of a changing commercial and social environment. Long-term resource sustainability is dependent both on increased efficiency, which improves profitability, and on revitalizing marginal mines. This is illustrated through breakthroughs in the processing of low-grade copper and refractory gold ores, as well as nickel laterite ores. Retreatment of mine wastes and tailings can also increase the sustainability of mining activity. Ongoing research and development is also helping to sustain mineral resource exploitation.
DS2000-0219
2000
De Villiers, S.De Villiers, S., Compton, J.S., Lavelle, M.The strontium isotope systematics of the Orange River, Southern AfricaSouth African Journal of Geology, Vol. 103, pp. 237-48.South Africa, southern AfricaWeathering - chemical, geochemistry
DS201804-0671
2018
De Vito, C.Aurisicchio, C., Conte, A.M., Medeghini, L., Ottolini, L., De Vito, C.Major and trace element geochemistry of emerald from several deposits: implications for genetic models and classification schemes.Ore Geology Reviews, Vol. 94, pp. 351-366.Globalemerald classification

Abstract: In the present work, we report the chemical composition of representative emerald crystals from some of the most important worldwide deposits. Major and trace elements were investigated using Electron Microprobe Analysis (EMPA) and Secondary Ion Mass Spectrometry (SIMS) techniques. Binary, ternary and spider diagrams along with statistical analysis, i.e., Principal Component Analysis (PCA), were used to discriminate each deposit with high reliability. PCA of SiO2, Al2O3, V, Sc, B, Li content identified distinct groups. The use of binary and ternary diagrams contributed to discriminate among emerald crystals from various deposits, which are included in the same clusters of the PCA analysis. In addition, the geochemical features of each group were linked to the geological environment and genetic processes which leaded to emerald formation. In particular, the emeralds related to granitic-pegmatitic intrusions (Type-1) or those occurring in environments controlled by tectonic events (Type-2) were distinguished using the concentrations of major and trace elements. The results of this study can contribute to improve the existing genetic models and classification schemes as well as to identify useful geochemical fingerprints for provenance purposes.-
DS2003-0326
2003
De Vivo, B.De Vivo, B., Bodnar, R.J.Melt inclusions in volcanic systemshttp://www.elsevier.com/inca/publications/store/6/7/2/8/0/7/672807.pub.htt, 272p. approx. $ 115.GlobalBook - liquid to glass, magma degassing, melt inclusion
DS2003-0327
2003
De Vivo, B.De Vivo, B., Bodnar, R.J.Melt inclusions in volcanic systemsElsevier Developments in Volcanology, 5, 272p. $ 115. www.elsevier.com/inca/publications/store/MantleBook
DS200412-0428
2003
De Vivo, B.De Vivo, B., Bodnar, R.J.Melt inclusions in volcanic systems.Elsevier, 272p. approx. $ 115.TechnologyBook - liquid to glass, magma degassing, melt inclusion
DS200512-0227
2004
De Vivo, B.De Vivo, B., Lima, A., Webster, J.D.Volatiles in magmatic volcanic systems.Elements, Vol. 1, 1, Jan. pp. 19-24.Melt inclusions, volatiles
DS1982-0460
1982
De voogd, B.Nelson, B.K., Lillie, R.J., De voogd, B., Brewer, J.A., Oliver.Cocorp Seismic Reflection Profiling in the Ouachita MountainTectonics, Vol. 1, No. 5, PP. 413-430.United States, Gulf Coast, ArkansasBlank
DS1983-0408
1983
De voogd, B.Lillie, R.J., Nelson, K.D., De voogd, B., Brewer, J.A., Oliver.Crustal Structure of Ouachita Mountains Arkansaw; a Model Based OnAmerican Association of Petroleum Geologists, Vol. 67, No. 6, PP. 907-931.GlobalMid-continent
DS200612-0226
2006
De Vries, D.F.Carswell, D.A., Van Roermund, H.L.M., De Vries, D.F., WiggersScandian ultrahigh pressure metamorphism of Protereozoic basement rocks on Fjortoft and Otroy, western Gneiss region, Norway.International Geology Review, Vol. 48, 11, pp. 957-977.Europe, NorwayUHP
DS201604-0600
2016
De Vries, J.De Vries, J., Nimmo, F., Melosh, H., Jacobson, S., Morbidelli, A., Rubie, D.Impact induced melting during accretion of the Earth.Progress in Earth and Planetary Science, Vol. 3, 7p.MantleMelting

Abstract: Because of the high energies involved, giant impacts that occur during planetary accretion cause large degrees of melting. The depth of melting in the target body after each collision determines the pressure and temperature conditions of metal-silicate equilibration and thus geochemical fractionation that results from core-mantle differentiation. The accretional collisions involved in forming the terrestrial planets of the inner Solar System have been calculated by previous studies using N-body accretion simulations. Here we use the output from such simulations to determine the volumes of melt produced and thus the pressure and temperature conditions of metal-silicate equilibration, after each impact, as Earth-like planets accrete. For these calculations a parameterised melting model is used that takes impact velocity, impact angle and the respective masses of the impacting bodies into account. The evolution of metal-silicate equilibration pressures (as defined by evolving magma ocean depths) during Earth’s accretion depends strongly on the lifetime of impact-generated magma oceans compared to the time interval between large impacts. In addition, such results depend on starting parameters in the N-body simulations, such as the number and initial mass of embryos. Thus, there is the potential for combining the results, such as those presented here, with multistage core formation models to better constrain the accretional history of the Earth.
DS201212-0756
2012
De Waal, D.Verster, A., De Waal, D., Schall, R., Prins, C.A truncated Pareto model to estimate the under recoveru of large diamonds.Mathematical Geosciences, Vol. 44, 1, pp. 91-100TechnologyRecovery
DS201606-1126
2012
de Waal, D.Verster, A., de Waal, D., Schall, R., Prins, C.A truncated Pareto model to estimate the under recovery of large diamonds. Bayesian approach.Mathematical Geosciences, Vol. 44, 1, pp. 91-100.TechnologyMetallurgy process

Abstract: The metallurgical recovery processes in diamond mining may, under certain circumstances, cause an under-recovery of large diamonds. In order to predict high quantiles or tail probabilities we use a Bayesian approach to fit a truncated Generalized Pareto Type distribution to the tail of the data consisting of the weights of individual diamonds. Based on the estimated tail probability, the expected number of diamonds larger than a specified weight can be estimated. The difference between the expected and observed frequencies of diamond weights above an upper threshold provides an estimate of the number of diamonds lost during the recovery process.
DS1995-1682
1995
De Waal, S.A.Schweitzer, J.K., Hatton, C.J., De Waal, S.A.Economic potential of the Rooiberg Group: volcanic rocks in the floor and roof of the Bushveld ComplexMineralium Deposita, Vol. 30, No. 2, pp. 168-177South AfricaGeochronology, granites, Bushveld Complex
DS1997-0260
1997
De Waal, S.A.De Waal, S.A., Gauert, C.D.K.The Basal Gabbro Unit and the identity of the parental magma of the Uitkomst Complex, Badplaas, South Africa.South African Journal of Geology, Vol. 100, 4, Dec. pp. 349-361.South AfricaLayered intrusion, Harzburgite
DS200712-0847
2006
De Waeel, B.Pisarevsky, S.A., Gladkochub, D.P., Donskaya, T.A., De Waeel, B., Mazukabzov, A.M.Paleomagnetism and geochronology of mafic dykes in south Siberia, Russia: the first precisely dated Permian paleomagnetic pole from the Siberian Craton.Geophysical Journal International, Vol. 167, 2, pp. 649-658.RussiaGeochronology
DS200512-0483
2005
De Waele, B.Johnson, S.P., Rivers, T., De Waele, B.A review of Mesoproterozoic to early Paleozooic magmatic and tectonothermal history of south central Africa: implications for Rodinia and Gondwana.Journal of the Geological Society, Vol. 162, 3, pp. 433-450.Africa, GondwanaMagmatism, geothermometry
DS200912-0147
2009
De Waele, B.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
DS201012-0612
2010
De Waele, B.Ratre, K., De Waele, B., Kumar, Biswal, T., Sinha, S.Shrimp geochronology for the 1450 Ma Lakhna dyke swarm: its implication for the presence of Eoarchean crust in the Bastar Craton and the 1450-517 Ma depositional ageJournal of Asian Earth Sciences, Vol. 39, 6, pp. 565-577.IndiaGeochronology
DS201312-0315
2013
De Waele, B.Gladkochub, D.P., Kostrovitskii, S.I., Donskaya, T.V., De Waele, B., Mazukabzov, A.M.Age of zircons from diamond bearing lamproites of the East Sayan as an indicator of known and unkonwn endogenous events in the south Siberian craton.Doklady Earth Sciences, Vol. 450, 2, June pp. 597-601.Russia, SayanLamproite
DS201709-1954
2017
De Waele, B.Armistead, S.E., Collins, A.S., Payne, J.L., Foden, J.D., De Waele, B., Shaji, E., Santosh, M.A re-evaluation of the Kumta Suture in western peninsular India and its extension into Madagascar,Journal of Asian Earth Sciences, in press available, 47p.India, Africa, Madagascartectonis

Abstract: It has long been recognised that Madagascar was contiguous with India until the Late Cretaceous. However, the timing and nature of the amalgamation of these two regions remain highly contentious as is the location of Madagascar against India in Gondwana. Here we address these issues with new U-Pb and Lu-Hf zircon data from five metasedimentary samples from the Karwar Block of India and new Lu-Hf data from eight previously dated igneous rocks from central Madagascar and the Antongil-Masora domains of eastern Madagascar. New U-Pb data from Karwar-region detrital zircon grains yield two dominant age peaks at c. 3100 Ma and c. 2500 Ma. The c. 3100 Ma population has relatively juvenile eHf(t) values that trend toward an evolved signature at c. 2500 Ma. The c. 2500 Ma population shows a wide range of eHf(t) values reflecting mixing of an evolved source with a juvenile source at that time. These data, and the new Lu-Hf data from Madagascar, are compared with our new compilation of over 7000 U-Pb and 1000 Lu-Hf analyses from Madagascar and India. We have used multidimensional scaling to assess similarities in these data in a statistically robust way. We propose that the Karwar Block of western peninsular India is an extension of the western Dharwar Craton and not part of the Antananarivo Domain of Madagascar as has been suggested in some models. Based on eHf(t) signatures we also suggest that India (and the Antongil-Masora domains of Madagascar) were palaeogeographically isolated from central Madagascar (the Antananarivo Domain) during the Palaeoproterozoic. This supports a model where central Madagascar and India amalgamated during the Neoproterozoic along the Betsimisaraka Suture.
DS200612-1466
2006
De Weedt, F.Van Royan, J., De Weedt, F., De Gryse, O.HPHT treatment of Type Ia brown diamonds.GIA Gemological Research Conference abstract volume, Held August 26-27, p. 37. 1/2p.TechnologyHPHT
DS1970-0899
1974
De Wet, J.J.De Wet, J.J.Carbonatites and Related Rocks at Saltpetre Kop, Sutherland, Cape Province.Msc. Thesis, University Stellenbosch, South Africa, SutherlandOlivine Melilite, Kimberlite, Melnoite
DS201412-0933
2014
De Wet, M.Toledo, V., Ward, J., De Wet, M., Spaggiari, R., Coopersmith, H.Developing a geological model to guide placer exploration in the Kishon catchment, northern Israel.Shefa Yamin Exploration & Mining, 2p. Poster and 1 page abstractEurope, IsraelKishon Placers
DS1989-0343
1989
De Wetterle Bonow, C.De Wetterle Bonow, C.Technical contribution in equating a problem at Brazilian ore prospectareasMin. Technology, Vol. 71, No. 830, December pp. 370-371BrazilDiamond mining, Garimpeiros
DS201012-0848
2010
De Winter, D.A.M.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
DS201112-0231
2011
de Winter, D.A.M.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
DS1991-0124
1991
De WitBizzi, L.A., Smith, C.B., Meyer, H.O.A., Armstrong, R., De WitMesozoic kimberlites and related alkalic rocks in south-western Sao Francisco craton, Brasil: a case of local mantle reservoirs and theirinteractionProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 17-19BrazilCraton -Sao Francisco, Monticellite, geothermometry, isotopes
DS1998-0172
1998
De WitBrown, R.W., Gallagher, Griffin, Ryan, De Wit, BeltonKimberlites, accelerated erosion and evolution of the lithospheric mantle beneath Kaapvaal - mid-Cretaceous..7th International Kimberlite Conference Abstract, pp. 105-107.South AfricaHeat flow data, uplift, Kaapvaal Craton
DS1998-1204
1998
De WitRakotosolofo, N.A., Torsvik, Ashwal, De Wit, EideMadagascar during the Late Paleozoic and MesozoicJournal of African Earth Sciences, Vol. 27, 1A, p. 148. AbstractMadagascarTectonics
DS1998-1477
1998
De WitTorsvik, T., Tucker, Ashwal, Eide, Rakotosolofo, De WitMadagascar: Cretaceous volcanism and the Marian hot spotJournal of African Earth Sciences, Vol. 27, 1A, p. 197. AbstractMadagascarvolcanism., Plume
DS201312-0201
2013
De WitDe Wit, MikeThe Xandiam kimberlite province straddling the southern margin of the Angolan craton. Nxau Nxau, Sikerti, Gura, Kaudom, Tsumkwe, OndatakoCAG 24 held in Addis Abada, Jan. 12, 41 slidesAfrica, Botswana, NamibiaOverview - geology
DS1987-0094
1987
de Wit, M.Cawthorn, R.G., Maske, S., de Wit, M., Groves, D.I., Cassidy, K.Mineralogical geochemical indicators of the formation conditions of apatite bearing carbonatites of the Arbarastakh Massif,Southern Yakutia (USSR).(Russian)Canadian Mineralogist, In pressSouth AfricaGenesis, Magma
DS1994-0166
1994
De Wit, M.Bizzi, L.A., Smith, C.B., De Wit, M., Macdonald, I., Armstrong, R.A.Isotopic characteristics of the lithospheric mantle underlying the southwest Sao Francisco craton margin, Brasil.International Symposium Upper Mantle, Aug. 14-19, 1994, pp. 227-255.BrazilGeochronology, Craton
DS1994-0412
1994
De Wit, M.De Ronde, C.E.J., De Wit, M.Tectonic history of the Barberton greenstone belt, South Africa: 490 myears of Archean crustal evolution.Tectonics, Vol. 13, No. 4, Aug. pp. 983-1005.South AfricaArchean, Crust - evolution tectonics
DS1996-0182
1996
De Wit, M.Brown, R., Gallagher, K., De Wit, M., Gleadow, A.The Cratonic conundrum: does old+cold+thick=stable?Australia Nat. University of Diamond Workshop July 29, 30. abstract, 1p.South Africa, BrazilCraton, Paleotemperatures
DS1997-0261
1997
De Wit, M.De Wit, M., Ashwal, L.D.Greenstone beltsOxford Press, 850p. $ 450.00Northwest Territories, Ontario, Wyoming, West AfricaBrasil, Zimbabwe, Amazon, South Africa, Tanzania, Zaire, Australia, Baltic
DS1999-0162
1999
De Wit, M.De Wit, M., Thiart, C., Doucoure, M., Wilsher, W.Scent of a supercontinent: Gondwana's ores as chemical tracers... tin, tungsten and Neoproterozoic...Journal of African Earth Sciences, Vol. 28, No. 1, pp. 35-51.Gondwana, RodiniaLaurentia - Gondwana connection, Tectonics - not specific to diamonds
DS2000-0808
2000
De Wit, M.Reeves, C., De Wit, M.Making ends meet in Gondwana: retracing the transforms of the Indian Ocean and reconnecting continental shearTerra Nova, Vol. 12, No. 6, Dec.pp. 272-80.India, Madagascar, GondwanaGeochronology, Gondwana, tectonics
DS2002-1323
2002
De Wit, M.Reeves, C.V., Sahu, B.K., De Wit, M.A re-examination of the paleo position of Africa's eastern neighbours in GondwanaJournal of African Earth Sciences, Vol.34, No.3-4,April-May pp. 101-8.Africa, GondwanaTectonics
DS2003-0328
2003
De Wit, M.De Wit, M.Madagascar: heads it's a continent, tails it's an islandAnnual Review of Earth and Planetary Sciences, Vol. 31, pp.MadagascarReview - geology, orogeny
DS200412-0429
2003
De Wit, M.De Wit, M.Madagascar: heads it's a continent, tails it's an island.Annual Review of Earth and Planetary Sciences, Vol. 31, pp.213-48.Africa, MadagascarReview - geology, orogeny
DS200412-0430
2004
De Wit, M.De Wit, M., Tinker, J.Crustal structure across the central Kaapvaal Craton from deep seismic reflection data.South African Journal of Geology, Vol. 107, 1/2, pp. 185-206.Africa, South AfricaGeophysics - seismics, tectonics, tomography
DS200712-0229
2007
De Wit, M.De Wit, M.Canteen Koppie at Barkly West: South Africa's first diamond mine. Fantastic historical presentation. 1869-1989Diamonds in Kimberley Symposium & Trade Show, Bristow and De Wit held August 23-24, Kimberley, South Africa, GSSA Diamond Workshop CD slides 95-131Africa, South AfricaHistory - Canteen Koppie
DS200812-0275
2007
De Wit, M.De Wit, M.The Kalahari epeirogeny and climate change: differentiating cause and effect from core to space.South African Journal of Geology, Vol. 110, 2-3, Sept. pp. 367-391.Africa, South AfricaTectonics
DS200812-0276
2008
De Wit, M.De Wit, M.Diamond 'Out of Africa': the world's leading source of revenue and knowledge about their origins.GSSA-SEG Meeting Held July, Johannesburg, 35 Power point slidesAfricaDiamond production - history, current
DS200812-0277
2007
De Wit, M.De Wit, M., Horsfield, B.Built on the shoulders of Alfred Wegener and Alex du Toit to apply German precision technology to the geological superlatives of South Africa.South African Journal of Geology, Vol. 110, 2-3, Sept. pp. 165-174.Africa, South AfricaTechnology
DS200812-1112
2007
De Wit, M.Stankiewicz, J., Ryberg, T., Schulze, A., Lindeque, A., Weber, M.H., De Wit, M.Initial results from wide angle seismic refraction lines in the southern Cape.South African Journal of Geology, Vol. 110, 2-3, Sept. pp. 407-418.Africa, South AfricaGeophysics - seismics
DS200912-0676
2009
De Wit, M.Schoene, B., Dudas, F.O.L., Bowring, S., De Wit, M.Sm Nd isotopic mapping of lithospheric growth and stabilization in the eastern Kaapvaal craton.Terra Nova, Vol. 21, 3, pp. 219-228.Africa, South AfricaGeochronology
DS201112-0669
2011
De Wit, M.Michael, W.R., Le Goff, M., De Wit, M.Anatomy of a pressure induced, ferromagnetic to paramagnetic transition in pyrrhotite: implications for formation pressure of diamonds.Journal of Geophysical Research, Vol. 116, B 10, B10101,MantleDiamond genesis
DS201212-0156
2012
De Wit, M.De Wit, M., Fumes, H.Earth's oldest preserved unconformity: prospect of a beginning in the tectono-sedimentary continental cycle?Gondwana Research, in pressEurope, GreenlandUnconformity
DS201212-0766
2012
de Wit, M.Weckmann, U., Ritter, O., Chen, X., Tietze, K., de Wit, M.Magnetotelluric image linked to surface geology across the Cape Fold Belt, South Africa.Terra Nova, Vol. 24, 3, pp. 207-212.Africa, South AfricaGeophysics
DS201412-0144
2014
De Wit, M.Coopersmith, H., Toledo, V., Fritsch, E., Ward, J., De Wit, M., Spaggiari, R.Geology and exploration of gem deposits at Mt. Carmel, northern Israel: natural moissanite, sapphire, ruby and diamond.Geological Society of America Conference Vancouver Oct. 19-22, 2p. AbstractEurope, IsraelMoissanite
DS201412-0177
2014
De Wit, M.De Wit, M.Setting the scene as to where diamond exploration is going!GSSA Kimberley Diamond Symposium and Trade Show provisional programme, Sept. 11, title onlyGlobalDiamond exploration
DS201412-0178
2014
De Wit, M.De Wit, M., Ward, J.The Proterozoic Marange alluvial diamond deposit in eastern Zimbabwe: is this a Mega-placer?Vancouver Kimberlite Cluster, March 7, 1p. AbtsractAfrica, ZimbabweDeposit - Marange
DS201505-0248
2015
de Wit, M.Toledo, V., Ward, J., de Wit, M., Spaggiari, R., Coopersmith, H., Wald, R.A transient fluvial placer in the mid reach of the Kishon Valley northern Israel: initial results of follow up exploration.Israel Geological Society, 1p.posterEurope, IsraelExploration results
DS201601-0012
2016
De Wit, M.De Wit, M.Southern Africa diamond producing projects - a summary.PDAC, 1p. AbstractAfrica, southern AfricaHistory- overview
DS201607-1343
2016
De Wit, M.De Wit, M.Dwyka age Diamondiferous eskers in the Lichtenburg/Ventersdorp diamond fields, North West Province, South AfricaIGC 35th., Session A Dynamic Earth 1p. AbstractAfrica, South AfricaAlluvials, diamonds
DS201609-1715
2010
De Wit, M.De Wit, M.Identification of global diamond metallogenic clusters to assist exploration.The 4th Colloquium on Diamonds - source to use held Gabarone March 1-3, 2010, 24p.GlobalDatabase, ages

Abstract: Of the approximately 6,500 kimberlites known to date, less than 3% are diamondiferous and less than half of those are economically viable. Admittedly, this is a global figure and varies from area to area much depending on geological, logistical, and political circumstances. The number of diarnond~bearing kimberlites is an important geobarometer, and an age-frequency profile has been compiled in order to identify diamond metallogenic epochs and provinces. Four primary diamond clusters have been recognised: Siberia (332-370Ma), Kaapvaal South(114-144Ma), Kaapvaal Southwest(84-95Ma), and Slave (52-55Ma). In addition, three secondary clusters are the Kaapvaal Central (S06-S38Ma), the Man Craton (139-lS3Ma) and the Kasai Craton (120- 130Ma). The Kaapvaal is the only area where kimberlites with diamonds were discovered between 1870 and 1925, except for the Prairie Creek discovery in North America in 1906 and Colossus in Zimbabwe in 1907. Between 1906 and 1940 no major diamondiferous kimbcrlites were discovered, but many of Africa's alluvial deposits were found and exploited in that period. Advances in scientific prospecting in the 1940's rapidly accelerated the discovery rate that peaked in the 1990's; 39 diamondiferous occurrences were found in the 1980's, of which 8 became mines and 5 are in feasibility, and nearly 450ha of kimberlite was added to the global resource base. Despite the accelerated exploration expenditure, the last decade (e.g. 2000-2009) has been the leanest since the 1940's. The most important reason for this decline in exploration success is that any undiscovered deposits are largely buried by younger cover. Understanding complex and geophysical noisy basement geology, as well as decomposition of path-finder minerals are major challenges to further exploration success. Major investments in basic geological expertise and field research will have to be made in order to secure future diamond resources. Integrated geophysical studies, geochemistry diamond forensics, and improved imaging of Earth's upper mantle are perhaps foremost in this requirement, but the costs of these activities are such that government support will be required if countries are to sustain their diamond mining industry.
DS201609-1716
2016
De Wit, M.De Wit, M., Bhebhe, Z., Davidson, J., Haggerty, S.E., Hundt, P., Jacob, J., Lynn, M., Marshall, T.R., Skinner, C., Smithson, K., Stiefenhofer, J., Robert, M., Revitt, A., Spaggiari, R., Ward, J.Overview of diamonds resources in Africa.Episodes, Vol. 9, 2, pp. 198-238.AfricaDiamond resources - overview

Abstract: From the discovery of diamonds in South Africa in 1866 until the end of 2013, Africa is estimated to have produced almost 3.2 Bct out of a total global production of 5.03 Bct, or 63.6% of all diamonds that have ever been mined. In 2013 African countries ranked 2nd (Botswana), 3rd (DRC), 6th (Zimbabwe), 7th (Angola), 8th (South Africa), and 9th (Namibia), in terms of carat production and 1st (Botswana), 4th (Namibia), 5th (Angola), 6th (South Africa), 7th (Zimbabwe), and 9th (DRC), in terms of value of the diamonds produced. In 2013 Africa produced 70.6 Mct out of a global total of 130.5 Mct or 54.1%, which was valued at US$ 8.7 billion representing 61.5% of the global value of US$ 14.1 billion.
DS201708-1624
2017
De Wit, M.De Wit, M.Prospecting history leading to the discovery of Botswana's diamond mines: from artifacts to Lesedi La Rona.11th. International Kimberlite Conference, OralAfrica, BotswanaHistory
DS201801-0070
2018
de Wit, M.Tappe, S., Smart, K., Torsvik, T., Massuyeau, M., de Wit, M.Geodynamics of kimberlites on a cooling Earth: clues to plate tectonic evolution and deep volatile cycles.Earth and Planetary Science Letters, Vol. 484, pp. 1-14.Mantlekimberlite, origin, magmatism

Abstract: Kimberlite magmatism has occurred in cratonic regions on every continent. The global age distribution suggests that this form of mantle melting has been more prominent after 1.2 Ga, and notably between 250-50 Ma, than during early Earth history before 2 Ga (i.e., the Paleoproterozoic and Archean). Although preservation bias has been discussed as a possible reason for the skewed kimberlite age distribution, new treatment of an updated global database suggests that the apparent secular evolution of kimberlite and related CO2-rich ultramafic magmatism is genuine and probably coupled to lowering temperatures of Earth's upper mantle through time. Incipient melting near the CO2- and H2O-bearing peridotite solidus at >200 km depth (1100-1400?°C) is the petrologically most feasible process that can produce high-MgO carbonated silicate melts with enriched trace element concentrations akin to kimberlites. These conditions occur within the convecting asthenospheric mantle directly beneath thick continental lithosphere. In this transient upper mantle source region, variable CHO volatile mixtures control melting of peridotite in the absence of heat anomalies so that low-degree carbonated silicate melts may be permanently present at ambient mantle temperatures below 1400?°C. However, extraction of low-volume melts to Earth's surface requires tectonic triggers. Abrupt changes in the speed and direction of plate motions, such as typified by the dynamics of supercontinent cycles, can be effective in the creation of lithospheric pathways aiding kimberlite magma ascent. Provided that CO2- and H2O-fluxed deep cratonic keels, which formed parts of larger drifting tectonic plates, existed by 3 Ga or even before, kimberlite volcanism could have been frequent during the Archean. However, we argue that frequent kimberlite magmatism had to await establishment of an incipient melting regime beneath the maturing continents, which only became significant after secular mantle cooling to below 1400?°C during post-Archean times, probably sometime shortly after 2 Ga. At around this time kimberlites replace komatiites as the hallmark mantle-derived magmatic feature of continental shields worldwide. The remarkable Mesozoic-Cenozoic ‘kimberlite bloom’ between 250-50 Ma may represent the ideal circumstance under which the relatively cool and volatile-fluxed cratonic roots of the Pangea supercontinent underwent significant tectonic disturbance. This created more than 60% of world's known kimberlites in a combination of redox- and decompression-related low-degree partial melting. Less than 2% of world's known kimberlites formed after 50 Ma, and the tectonic settings of rare ‘young’ kimberlites from eastern Africa and western North America demonstrate that far-field stresses on cratonic lithosphere enforced by either continental rifting or cold subduction play a crucial role in enabling kimberlite magma transfer to Earth's surface.
DS201807-1489
2018
de Wit, M.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; 2s) 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 (2s). 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.
DS201907-1540
2019
de Wit, M.de Wit, M.In the world of diamonds, the Big and Beautiful size does matter!Junior Indaba held Johannesburg June 4, 35 ppts. PdfGlobaldiamonds notable
DS202011-2038
2020
De Wit, M.De Wit, M.Botswana's World Class Diamond Mines.https://www.youtube.com /watch?v=GoqjOMoUw3I, 1hr long Africa, BotswanaHistory
DS202011-2065
2020
De Wit, M.Vainer, S., Matmon, A., Erel, A.J., Hidy, A.J., Crouvi, O., De Wit, M., Geller, Y.Landscape responses to intraplate deformation in the Kalahari constrained by sediment provenance and chronology in the Okavango Basin.Basin Research, in press available Africa, South Africageomorphology

Abstract: The structural depression that occupies the Okavango Basin in southern Africa comprises a depo-centre within the intracratonic Kalahari Basin where sediments of the Cenozoic Kalahari Group have accumulated. The Okavango Basin has been formed due to stretching and subsidence at an area of diffused deformation, southwestwards to the main East African Rift System (EARS). Sediments from two full Kalahari Group sequences, located on opposite sides of the Gumare Fault that forms a major fault within the Okavango Basin, were studied to determine their provenance and chronology. Terrestrial Cosmogenic Nuclide (TCN) 26Al/10Be burial dating was used to constrain a chronostratigraphical framework, and Pb, Sr, and Nd isotopic ratios combined with geochemical and sedimentological analyses were applied to track the source areas of the sediments.Results indicate the following sequence of basin filling: (a) Accumulation between ca. 4-3 Ma during which the currently downthrown (southern) block received a mixture of sediments mostly from the Choma-Kalomo, Ghanzi-Chobe, and Damara terranes, and possibly from the Lufilian Belt and/or Karoo basalts during earlier stages of deposition. Simultaneously, the upthrown (northern) block received sediments from more distant Archean sources in the Zimbabwe and/or Kasai cratons, (b) Hiatus in sedimentation occurred at both sites between ca. 3-2 Ma, (c) Sediments on both sides of the Gumare Fault share a similar source (Angolan Shield) with minor distinct contributions to the downthrown block from the Kasai Craton and local sources input to the upthrown block, and (d) Regional distribution of aeolian sand since at least 1 Ma. The change in source areas is attributed to rearrangements of the drainage systems that were probably linked to vertical crustal movements on the margins of the Okavango Basin. The tectonically induced morphodynamics controlled the landscape evolution of the endorheic basin where vast lakes, wetlands and salt pans have developed through time.
DS1994-1145
1994
De Wit, M..McDonald, I., Bizzi, L.A., De Wit, M..The geochemistry (platinum group elements (PGE)) in kimberlites and constraints of the nature platinum group elements (PGE) insubcratonic lithospheric mantle.International Symposium Upper Mantle, Aug. 14-19, 1994, Extended abstracts pp. 73-75.Brazil, South AfricaKimberlites, Geochemistry
DS1995-0405
1995
De Wit, M.C.De Wit, M.C.Alluvial diamond placers in South AfricaCentennial Geocongress (1995) Extended abstracts, Vol. 1, p. 63. abstractSouth AfricaAlluvials, Placers
DS1996-0352
1996
De Wit, M.C.De Wit, M.C.The distribution and stratigraphy of In land alluvial diamond deposits In south Africa.Africa Geoscience Review, Vol. 3, No. 2, pp. 175-189.South AfricaAlluvial diamonds, Distribution, stratigraphy
DS201312-0957
2013
De Wit, M.C.Ward, J.D., De Wit, M.C., Revitt, A.W., Abson, J.P.Geological and economic aspects of the Proterozoic Umkondo Group diamond placer near Marange, Zimbabwe.Geoforum , 32ppt. AvailableAfrica, ZimbabweDeposit - Marange area
DS201803-0440
2018
De Wit, M.C.De Wit, M.C.Prospecting history leading to the discovery of Botswana's diamond mines: from artefacts to Lesedi La Rona.Mineralogy and Petrology, in press available, 16p.Africa, Botswanadiamond exploration

Abstract: Bechuanaland/Botswana has a long and colourful history in exploration and mining. Here these activities are subdivided into three phases: pre-historic, historic and modern. Quarrying stone in Botswana was ongoing 500,000 years ago during the Early Stone Age (ESA). Actual mining of stones probably only started during the Middle Stone Age (MSA) i.e. post 250,000 BP, and the first prehistoric hard rock mining of specularite and limonite, likely started during the Late Stone Age (LSA) 20,000 to 2,000 BP. In east Botswana iron and copper were mined from AD 800 onwards; the mining of gold started in the thirteenth century. Historic mining started with the re-discovery of gold close to Francistown in 1865 and lasted until the 1950s. Rumours of diamonds in Bechuanaland had already surfaced in the 1880s, and it was Ngamiland, in the northwest, that was first explored systematically for diamonds and gold between 1896 and 1899. A joint initiative between Anglo American and De Beers started serious prospecting parts of eastern Bechuanaland between 1932 and 1938; and in 1938 the first diamond finds in Bechuanaland were reported. Modern mining and exploration started with the signing of an agreement in 1959, allowing Consolidated African Selection Trust Ltd. (CAST) into the Bamangwato Tribal Reserve. CAST found a few diamonds in the Motloutse River, but concluded that these were reworked and dropped the exploration rights. De Beers believed that these diamonds had come from west of the Motloutse headwaters, across the watershed in the Kalahari. This ultimately led to the discovery of the Orapa kimberlite field in 1967, a year after Botswana became independent. This discovery triggered a major exploration boom across Botswana adding important diamond-bearing kimberlites such as at Letlhakane (1968), Jwaneng (1973), Gope (1981) and Lerala (1991).
DS1999-0163
1999
De Wit, M.C. J.De Wit, M.C. J.Post Gondwana drainage and the development of diamond placers in western South Africa.Economic Geology, Vol. 94, No. 5, Aug. pp. 721-40.South AfricaDiamond - alluvials, Geomorphology
DS1988-0162
1988
De Wit, M.C.J.De Wit, M.C.J.The alluvial diggings of the Lower Vaal River-past and presentGeoBulletin, Vol. 31, No. 1, pp. 44-45South AfricaBlank
DS1998-0327
1998
De Wit, M.C.J.De Wit, M.C.J., Morelli, C., Skinner, C.P.A reinterpretation of the Lichtenburg diamond deposits7th International Kimberlite Conference Abstract, p. 195.South AfricaAlluvials, Deposit - Lichtenburg
DS1999-0697
1999
De Wit, M.C.J.Spaggiori, R.I., Ward, J.D., De Wit, M.C.J.Fluvial characteristics of the Diamondiferous Droogeveldt gravels, VaalValley, South Africa.Economic Geology, Vol. 94, No. 5, Aug. pp. 741-48.South AfricaDiamond alluvials, Droogeveldt area
DS2000-0220
2000
De Wit, M.C.J.De Wit, M.C.J.On the development of alluvial diamond deposits in central AfricaJournal of African Earth Sciences, p. 22. abstract.Africa, Central African Republic, Democratic Republic of CongoAlluvials - placers
DS2000-0221
2000
De Wit, M.C.J.De Wit, M.C.J., Marshall, T.R., Partridge, T.C.Fluvial deposits and drainage evolutionIn: The Cenozoic of Southern Africa, pp. 55-72.South AfricaGeomorphology - alluvials, tectonics, gravels
DS200512-0228
2004
De Wit, M.C.J.De Wit, M.C.J.The Diamondiferous sediments on the farm Nooitgedacht (66) Kimberley, South Africa.South African Journal of Geology, Vol. 107, 4, pp. 477-488.Africa, South AfricaDiamond sedimentology
DS200612-0141
2005
De Wit, M.C.J.Bluck, B.J., Ward, D.J., De Wit, M.C.J.Diamond megaplacers, southern Africa and the Kaapvaal Craton in a global context.Geological Society of London Special Paper, No. 248, pp. 213-246.Africa, South AfricaPlacers, alluvials
DS200712-0230
2007
De Wit, M.C.J.De Wit, M.C.J.Exploration for diamonds in the DRC.9th Biennial SGA Meeting held Dublin August 20-23, abstracts, Session 15,Africa, Democratic Republic of CongoNews item - exploration
DS200812-0278
2008
De Wit, M.C.J.De Wit, M.C.J.Canteen Koppie at Barkly West South Africa's first diamond mine.South African Journal of Geology, Vol. 11, 1, pp. 53-66.Africa, South AfricaDeposit - Canteen Koppie history
DS201012-0145
2009
De Wit, M.C.J.De Wit, M.C.J., Ward, J.D., Bamford, M.K., Roberts, M.J.The significance of the Cretaceous Diamondiferous gravel deposit at Mahura Mthla Northern Cape province, South Africa.South African Journal of Geology, Vol. 112, 2, pp. 89-108.Africa, South AfricaAlluvials
DS201503-0141
2015
De Wit, M.C.J.De Wit, M.C.J., Jelsma, H.A.A review of the kimberlites of the Democratic Republic of Congo.Geology and resource potential of the Congo Basin, Springer Regional Geology Reviews, Chapter 17, 9p.Africa, Democratic Republic of CongoOverview, history

Abstract: An overview is provided of the exploration history and geological setting of the kimberlites in the Democratic Republic of Congo (DRC). Exploration for diamonds, in what was then known as Congo Belge, started in 1900 and the first diamonds were found in 1903 in Shaba (now Katanga) Province, in 1907 in Kasai Occidental Province near Tshikapa Town and in 1918 in Kasai Oriental Province near Mbuji Mayi Town. While the Kundelungu kimberlites in Katanga Province were discovered in 1908, other kimberlite fields were discovered much later (Mbuji Mayi 1946; Tshibwe 1956; Bas-Congo 1974; Kasendou and Lukashi 2005), during exploration work by Forminière (Société Internationale Forestière et Minière du Congo-Tshikapa), MIBA (Societé Minière de Bakwanga-Mbuji Mayi), the De Beers Group and Bugeco S.A. Published age constraints on the kimberlites show Late Cretaceous ages for the Mbuji Mayi kimberlites (~70 Ma) and Eocene-Oligocene ages for the Kundelungu kimberlites (~32 Ma). Emplacement of the Late Cretaceous kimberlites (Mbuji Mayi, Tshibwe, Kasendou and Lukashi) was concomitant with the deposition of Cretaceous sedimentary sequences. The majority of the pipes show crater-facies preservation and some of the pipes are flared displaying so-called ‘champagne glass-shaped’ morphologies, suggesting emplacement into unconsolidated sediments overlying basement. The age of the Eocene-Oligocene Kundelungu kimberlites corresponds to lithospheric extension associated with the southward propagation of the East African Rift.
DS201503-0142
2015
De Wit, M.C.J.De Wit, M.C.J., Thorose, E.Diamond bearing gravels along the lower Kwango River, DRC.Geology and resource potential of the Congo Basin, Springer Regional Geology Reviews, Chapter 16, 20p.Africa, Democratic Republic of CongoOverview, history

Abstract: Since the mid-1950s the Kwango River has been a major target for alluvial diamonds which are and continue to be mined from its terraces, younger river flats and present-day river channel. The terraces have maximum ages of Early to Middle Pleistocene. Most of the diamonds have been recovered from large diamond placers in and along the Angolan section of this river—the Cuango River. Smaller deposits have been worked further downstream, where the Kwango River forms the international border between Angola and the Democratic Republic of Congo (DRC), also referred to as the ‘international’ Kwango. The prospecting history of this river goes back to 1906 but a systematic exploration program over the lower Kwango was only initiated in 2005. The application of geophysics to explore the terrace deposits and river flats has been very useful, but a programme of drilling and pitting was required to accurately define gravel and overburden thicknesses, and outline palaeo-channels. A diamond study used to glean information on diamond sizes and characteristics added significant value to the understanding of these alluvial deposits. For most of the international Kwango, terraces and river flats overly aeolian facies of Upper Kwango Group. Basement rocks, providing more favourable sites for diamond concentrations, are only exposed over a relatively short section, just upstream from Tembo. The basal part of the Cretaceous Kwango Group is locally composed of chemically mature gravels with diamonds in economic quantities only proximal to primary sources and no such settings were found in the project area. The size frequency of the diamonds from the international Kwango indicates that these form the distal head of the diamond trail that have been eroded out of the Cretaceous Kwango Group sediments and kimberlites in the Upper Cuango basin in Angola since the Pleistocene. The diamonds below the two major waterfalls along the international Kwango near Tembo, the Guiliame and Francois-Joseph Falls, show a high percentage of breakage and a decline in average diamond size from around 0.25 cts/stn above the falls to between 0.07 and 0.1 cts/stn in the Nzasi Muadi to Kitangu area between 20 km and 130 km below the Falls. However, local variations due to geomorphological influences affect diamond concentrations and sizes. A preliminary assessment of the terrace deposits suggests that these are uneconomic at present using modern mining methods. This is largely due to thick overburden (up to 12 m of sand) combined with thin and hence low-volume, medium-grade basal gravel, and the dominance of small diamonds of lower value.
DS201607-1292
2016
De Wit, M.C.J.De Wit, M.C.J.Dwyka-age Diamondiferous eskers in the Lichtenburg/Ventersdorp diamond fields, North West Province, South Africa.IGC 35th., 1p. AbstractAfrica, South AfricaDeposit - Lichtenburg Ventersdorp
DS201610-1856
2016
De Wit, M.C.J.De Wit, M.C.J., Dorkin, G., Morris, D.The alluvial diamonds deposits … of the north west province and the Lower Val-Middle Orange Basin.IGC 35th., Field Trip Guide pre-6 Aug. 22-27, 45p. PdfAfrica, South AfricaGuidebook - alluvials
DS201707-1318
2016
De Wit, M.C.J.De Wit, M.C.J.Early Permian diamond bearing proximal eskers in the Lichtenburg/Ventersdorp area of the north west province, South Africa.South African Journal of Geology, Vol. 119, 4, pp. 585-606.Africa, South Africadeposit - Lichtenburg Ventersdorp

Abstract: Diamond-bearing gravels of the Lichtenburg-Ventersdorp area of the North West Province are associated with north-south orientated sinuous ‘runs’ that occur almost entirely on a flat erosional surface of the Malmani dolomites (Transvaal Supergroup) at some 1,500 m elevation. East to west, this dolomite plain measures 150 km, and north-south it is on average 40 km wide. This unconformity, which first developed before the Pretoria Group sedimentation over a period of at least 80 Myr, is marked by siliceous breccias (palaeo-karst infill) and conglomerates (reworked breccias). It was exhumed in pre-Karoo and post-Gondwana times. Glacial pavements and remnants of thin Lower Karoo sediments are also found on this polyphase surface. The gravels that make up these ‘runs’ and sinkholes directly or indirectly linked to these runs, are coarse-grained, very poorly-sorted, and are best described as diamictites. The ‘runs’ are narrow, elongated, generally positive ridges that meander across the dolomite surface and are up to 30 km long and between 80 to 300 m wide. They have always been regarded as post-Cretaceous drainage features linked to southward-flowing river systems. Diamonds were discovered in these ‘runs’ and they have produced some 12 million carats. However, no Cainozoic fossils or artefacts have ever been found in almost 90 years of mining. From new field evidence, geomorphological studies, age dating from inclusions in diamond and zircon and clay analyses, it is proposed that these coarse-grained runs represent proximal palaeoeskers of the last deglaciation of the Dwyka continental ice sheet, that are preserved on this ancient ‘palimpsest’ surface. The age of the deposit is constrained by two populations of agate within the diamictites that are linked to two separate volcanic units of the Pretoria Group. In addition, the youngest crustal zircon ages from the gravels are 1 Ba, but mantle zircons from Lichtenburg suggest that these have been derived from Cambrian age kimberlites. Analysis of inclusions in diamond support a Neoproterozoic to Cambrian source for the diamonds, so the absence of diamonds from Mesozoic kimberlites and Cainozoic fossils within the gravels support the conclusion that the runs are of Karoo age.
DS201807-1523
2018
de Wit, M.C.J.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 (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.
DS201810-2366
2018
de Wit, M.C.J.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.
DS1990-0667
1990
De Wit, M.J.Hart, R.J., Andreoli, M.A.G., Tredoux, M., De Wit, M.J.Geochemistry across an exposed section of Archean crust at Vredefort, SouthAfrica: with implications for mid- crustal discontinuitiesChemical Geology, Vol. 82, No. 1/2, March 30, pp. 21-50South AfricaGeochemistry, Tectonics
DS1991-0358
1991
De Wit, M.J.De Wit, M.J., Roering, C.Formation of an Archean continent #2Terra Abstracts, Precambrian Sedimentary Basins of Southern Africa, ed., Vol. 3, suppl. 3 p. 8. AbstractSouth AfricaKaapval craton, Tectonics
DS1992-0352
1992
De Wit, M.J.De Wit, M.J., Roering, C., Hart, R.J., Armstrong, R.A., et al.Formation of an Archean continent #1Nature, Vol. 357, No. 6379, June 18, pp. 553-562South AfricaArchean continent, Structure
DS1992-1593
1992
De Wit, M.J.Van Reenen, D.D., Roering, C., Ashwal, L.D., De Wit, M.J.Regional geological setting of the Limpopo beltPrecambrian Research, Vol. 55, pp. 1-5South AfricaLimpopo Belt, Granulite terrane, craton
DS1993-0336
1993
De Wit, M.J.De Wit, M.J., Hart, R.A.Earth's earliest continental lithosphere, hydrothermal flux and crustalrecyclingLithos, Vol. 30, No. 3-4, September pp. 309-336MantleCrustal recycling, Thermometry, Lithosphere
DS1993-1649
1993
De Wit, M.J.Van Schalkwyk, J.F., De Wit, M.J., Roering, C., Van Reenen, D.D.Tectono-metamorphic evolution of the simatic basement of the Pietersburg greenstone belt relative to the Limpopo Orogeny: evidence from serpentinitePrecambrian Research, Vol. 61, No. 1-2, February pp. 67-88South AfricaTectonics, metamorphism, Greenstone belt
DS1994-0413
1994
de Wit, M.J.De Ronde, C.E.J., de Wit, M.J.Tectonic history of the Barberton greenstone belt: 490 million years of Archean crustal evolutionTectonics, Vol. 13, No. 4, August pp. 983-1005South AfricaTectonics, Barberton greenstone belt
DS1994-1146
1994
De Wit, M.J.McDonald, I., De Wit, M.J., Bizzi, L.A.The geochemistry of the Platinum group elements in kimberlites and the nature platinum group elements (PGE) in subcratonic mantle.Mineralogical Magazine, Vol. 58A, pp. 581-582. AbstractMantleGeochemistry, Platinum in kimberlites
DS1995-0154
1995
De Wit, M.J.Bizzi, L.A., De Wit, M.J., Smith, C.B.Isotope composition of the sub-continental lithosphere southwest Sao Francisco craton margin: clues to the mantle...Proceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 55-56.BrazilGeochronology, mantle reservoir source, Craton -Sao Francisco
DS1995-0406
1995
De Wit, M.J.De Wit, M.J.Gondwana GIS and supercontinental queriesEos, Abstracts, Vol. 76, No. 17, Apr 25, p. S 294.GondwanaTectonics
DS1995-0407
1995
De Wit, M.J.De Wit, M.J., Ashwal, L.D.Greenstone belts: what are they?South African Journal of Geology, Vol. 95, No. 4, pp. 505-520South Africa, GlobalGreenstone belts, Terminology, classification
DS1995-0762
1995
De Wit, M.J.Hart, R.J., De Wit, M.J., Tredoux, M.Refractory trace elements in diamonds: further clues to the origins of ancient cratons.Geological Society Africa 10th. Conference Oct. Nairobi, pp. 77-8. Abstract.South AfricaDiamond inclusions, Craton -Kaapvaal
DS1995-1208
1995
De Wit, M.J.McDonald, I., De Wit, M.J., Smith, C.B., Bizzi, L.A. etc.The geochemistry of platinum group elements in Brazilian and Southern african kimberlites.Geochimica et Cosmochimica Acta, Vol. 59, No. 14, July pp. 2883-2904.Brazil, South Africa, BotswanaGeochemistry -platinum group elements (PGE), Kimberlites
DS1996-0232
1996
De Wit, M.J.Carlson, R.W., Grove, T.L., De Wit, M.J., Gurney, J.J.Program to study crust and mantle of the Archean craton in southernAfrica.Eos, Vol. 77, No. 29, July 16, pp. 273, 277.South AfricaKaapvaal Craton, Chemistry, geochemistry, geochronology, geodynamics
DS1997-0482
1997
De Wit, M.J.Hart, R.J., Tredoux, M., De Wit, M.J.Refractory trace elements in diamond inclusions: further clues to the origins of the ancient cratons.Geology, Vol. 25, No. 12, Dec. pp. 1143-46.South Africa, BrazilEclogites, Peridotites, silicate, sulphide, Deposit - Finch, Premier
DS1998-0045
1998
De Wit, M.J.Armstrong, R., De Wit, M.J., et al.Cape Town's Table Mountain reveals rapid Pan-African uplift of its basementrocks.Journal of African Earth Sciences, Vol. 27, 1A, p. 10. AbstractSouth AfricaGondwana, tectonics, Pan-African rift
DS1998-0328
1998
De Wit, M.J.De Wit, M.J.Clues to Kennedy's Pan-African thermo-tectonismJournal of African Earth Sciences, Vol. 27, 1A, p. 55-7. AbstractAfrica, BrazilGondwana, Tectonics
DS1998-0329
1998
De Wit, M.J.De Wit, M.J.On Archean granites, greenstones, cratons and tectonics: does the evidence demand a verdict.Precambrian Research, Vol. 91, No. 1-2, Aug. 1, pp. 181-?MantleCraton, Magmatism - not specific to diamonds
DS1998-0330
1998
De Wit, M.J.De Wit, M.J., Ghosh, J.G., Bowring, S., Ashwal, L.Late Neoproterozoic shear zones in Madagascar and India: Gondwana"life-lines".Journal of African Earth Sciences, Vol. 27, 1A, p. 58. AbstractAfrica, Madagascar, IndiaGondwana, Tectonics
DS1998-0331
1998
De Wit, M.J.De Wit, M.J., Thiart, C., Doucoure, M.Gondwana mineralization and metallogenesisJournal of African Earth Sciences, Vol. 27, 1A, p. 58. AbstractGondwanaTectonics, Metallogeny - not specific to diamonds
DS1998-0361
1998
De Wit, M.J.Doucoure, C.M., De Wit, M.J., Reeves, C.V.Towards a gravity map of Gondwana #1Journal of African Earth Sciences, Vol. 27, 1A, p. 62. AbstractGondwanaGeophysics - gravity
DS1998-0504
1998
De Wit, M.J.Ghosh, J.G., Zartman, R.E., De Wit, M.J.Re-evaluation of tectonic framework of southern most India: new uranium-lead (U-Pb)geochronological and structural data.Journal of African Earth Sciences, Vol. 27, 1A, p. 86. AbstractIndia, southTectonics - not specific to diamonds, Geochronology
DS1998-1222
1998
De Wit, M.J.Reeves, C.V., De Wit, M.J.Gondwana re-assembly by retracing the transforms of the Indian OceanJournal of African Earth Sciences, Vol. 27, 1A, p. 156-7. AbstractGondwanaTectonics
DS1998-1485
1998
De Wit, M.J.Trouw, R.A.J., De Wit, M.J.Intracontinental deformation of Gondwana: fundamental shear zones and Gondwanide fold belts: links ...Journal of African Earth Sciences, Vol. 27, 1A, p. 200. AbstractGondwanaTectonics
DS1999-0164
1999
De Wit, M.J.De Wit, M.J.Gondwana - 10 Alex du Toit symposium event stratigraphy of GondwanaJournal of African Earth Sciences, Vol. 28, No. 1, pp. 11-15.Overview - brief of symposium specific papers list, Tectonics
DS1999-0744
1999
De Wit, M.J.Trouw, R.A., De Wit, M.J.Relation between the Gondwanide Orogen and contemporaneous intracratonicdeformation.Journal of African Earth Sciences, Vol. 28, No. 1, pp. 203-213.Lithosphere, Orogeny - craton
DS1999-0826
1999
De Wit, M.J.Zegers, T.E., De Wit, M.J., White, S.H.Vaalbara, Earth's oldest assembled continent? a combined structural, geochronological, paleomagnetic..Terra Nova, Vol. 10, No. 5, p. 250-259.Paleomagnetics, tectonics
DS2000-0244
2000
De Wit, M.J.Doucoure, C.M., De Wit, M.J., Reeves, C.V.Towards a gravity map of Gondwana #2Journal of African Earth Sciences, Vol.31, No.1, July, pp.195-204.GondwanaGeophysics - gravity, Map
DS2000-0809
2000
De Wit, M.J.Reeves, C.V., De Wit, M.J.Making ends meet in Gondwana: retracing the transforms of the Indian Ocean and reconnecting continental shear zones.Terra Nova, Vol. 12, pp. 272-280.Gondwana, Indian OceanTectonics, transcontinental
DS2002-0669
2002
De Wit, M.J.Harvey, J.D., De Wit, M.J., Stankiewicz, J., DoucoureStructural variations of the crust in the southwestern Cape, deduced from seismic receiver functions.South Africa Journal of Geology, Vol. 104, pp. 231-42.South AfricaKaapvaal Craton, Tectonics
DS2002-0777
2002
De Wit, M.J.Jelsma, H.A., Dirks, P.H.G.M., De Wit, M.J.Tectonics and metallogeny of Archean lithosphere in southern Africa11th. Quadrennial Iagod Symposium And Geocongress 2002 Held Windhoek, Abstract p. 28.South AfricaMagmatism
DS2002-1101
2002
De Wit, M.J.Moucoure, C.M., De Wit, M.J.Temporal variation in rigidity and mechanical behaviour of old thick continental lithosphere.Geological Society of South Africa, Vol. 105, No. 1, pp. 39-50.South AfricaMantle - tectonics
DS2002-1541
2002
De Wit, M.J.Stankiewicz, J., Chevrot, S., Van der Hilst, R.D., De Wit, M.J.Crustal thickness, discontinuity depth and upper mantle structure beneath southern Africa: constraints from body wave conversions.Physics of the Earth and Planetary Interiors, Vol. 130, No. 3-4, pp. 235-51.South AfricaGeophysics - seismics, Tectonics
DS2002-1596
2002
De Wit, M.J.Tinker, J., De Wit, M.J., Grotzinger, J.Seismic stratigraphic constraints on Neoarchean Paleoproterozoic evolution of the western margin of the Kaapvaal Craton, South Africa.Geological Society of South Africa, Vol. 105, No. 2, pp. 107-34.South AfricaGeophysics - seismics, craton - margin
DS2003-0120
2003
De Wit, M.J.Bluck, B.J., Ward, J.D., De Wit, M.J.The making of a diamond mega-placer on the margin of the Kalahari craton: guidelinesTransactions of the Institution of Mining and Metallurgy, Vol. 112, August p. 199. (1p.)South AfricaPlacers, alluvials
DS2003-0346
2003
De Wit, M.J.Doucoure, C.M., De Wit, M.J.Old inherited origin for the present near bimodal topography of AfricaJournal of African Earth Sciences, Vol. 36, 4, May pp. 371-88.AfricaTectonics, gravity, epirogeny, igneous magmatism
DS200412-0165
2003
De Wit, M.J.Bluck, B.J., Ward, J.D., De Wit, M.J.The making of a diamond mega-placer on the margin of the Kalahari craton: guidelines for future prospecting.Transactions of the Institution of Mining and Metallurgy, Vol. 112, August p. 199. (1p.)Africa, South AfricaPlacers, alluvials
DS200412-0431
2004
De Wit, M.J.De Wit, M.J., Richardson, S.H., Ashwal, L.D.Kaapvaal Craton special volume - an introduction.South African Journal of Geology, Vol. 107, 1/2, pp. 1-6.Africa, South AfricaHistory - Kaapvaal project
DS200412-0472
2003
De Wit, M.J.Doucoure, C.M., De Wit, M.J.Old inherited origin for the present near bimodal topography of Africa.Journal of African Earth Sciences, Vol. 36, 4, May pp. 371-88.AfricaTectonics, gravity, epirogeny, igneous magmatism
DS200412-0911
2004
De Wit, M.J.Jelsma, H.A., De Wit, M.J., Thiart, C., Dirks, P.H.G.M., Viola, G., Basson, U., Anckar, E.Preferential distribution along transcontinental corridors of kimberlites and related rocks of Southern Africa.South African Journal of Geology, Vol. 107, 1/2, pp. 302-324.Africa, South AfricaTectonics, structures, lineaments
DS200412-1504
2004
De Wit, M.J.Parman, S.W., Grove, T.L., Dann, J.C., De Wit, M.J.A subduction origin for komatiites and craton lithospheric mantle.South African Journal of Geology, Vol. 107, 1/2, pp. 107-118.Africa, South AfricaSubduction
DS200412-1645
2000
De Wit, M.J.Reeves, C.V., De Wit, M.J.Making ends meet in Gondwana: retracing the transforms of the Indian Ocean and reconnecting continental shear zones.Terra Nova, Vol. 12, pp. 272-280.Gondwana, Indian OceanTectonics, transcontinental
DS200412-1646
2004
De Wit, M.J.Reeves, C.V., De Wit, M.J., Sahu, B.K.Tight assembly of Gondwana exposes Phanerozoic shears in Africa as global tectonic players.Gondwana Research, Vol. 7, 1, pp. 7-20.AfricaTectonics
DS200412-1761
2004
De Wit, M.J.Schmitz, M.D., Bowring, S.A., De Wit, M.J., Gartz, V.Subduction and terrane collision stabilize the western Kaapvaal Craton tectosphere 2.9 billion years ago.Earth and Planetary Science Letters, Vol. 222, 2, pp. 363-376.Africa, South AfricaSubduction, tectonics, continental lithosphere
DS200412-1999
2004
De Wit, M.J.Tinker, J.H., De Wit, M.J., Royden, L.H.Old, strong continental lithosphere with weak Archean margin at 1.8 Ga, Kaapvaal Craton, South Africa.South African Journal of Geology, Vol. 107, 1/2, pp. 255-260.Africa, South AfricaGeochronology
DS200512-0229
2005
De Wit, M.J.De Wit, M.J.Helmstaedtian cratons and greenstone belts.GAC Annual Meeting Halifax May 15-19, Abstract 1p.Europe, IcelandArchean - craton
DS200512-1041
2005
De Wit, M.J.Stankiewicz, J., De Wit, M.J.River networks of southern Africa: scaling laws governing their geometry and deviations from scaling.Geochemistry, Geophysics, Geosystems: G3, In pressAfrica, South Africa, BotswanaGeomorphology, drainage
DS200712-0663
2007
De Wit, M.J.Mabidi, T., Thiart, C., De Wit, M.J.Secular changes recorded in mineralization in African crust.Journal of African Earth Sciences, Vol. 47, 2, Feb. pp. 88-94.AfricaMetallogeny - not specific to diamonds
DS200712-1048
2007
De Wit, M.J.Strik, G., De Wit, M.J., Langeris, C.G.Paleomagnetism of the NeoArchean Pongola and Ventersdorp Supergroups and an appriasal of the 3.0 - 1.9 Ga apparent polar wander path of Kaapvaal CratonPrecambrian Research, Vol. 153, 1-2, pp. 96-115.Africa, South AfricaPaleomagnetism
DS200812-0600
2007
De Wit, M.J.Kounov, A., Niedermann, S., De Wit, M.J., Andreoli, M., Erzinger, J.Present denudation rates at selected sections of the South African escarpment and the elevated continental interior based on cosmogenic 3He and 21Ne.South African Journal of Geology, Vol. 110, 2-3, Sept. pp. 235-248.Africa, South AfricaGeomorphology
DS200812-0668
2007
De Wit, M.J.Lindeque, A.S., Ryberg, T., Stankiewicz, J., Weber, M.H., De Wit, M.J.Deep crustal seismic reflection experiment across the Southern Karoo Basin, South Africa.South African Journal of Geology, Vol. 110, 2-3, Sept. pp. 419-438.Africa, South AfricaGeophysics - seismics
DS200812-1024
2008
De Wit, M.J.Schoene, B., De Wit, M.J., Bowring, S.Mesoarchean assembly and stabilization of the eastern Kaapvaal craton: a structural thermochronology perspective.Tectonics, Vol. 27, TC5010.Africa, South AfricaGeothermometry
DS201604-0601
2016
De Wit, M.J.De Wit, M.J., Furnes, H.3.5 Ga hydrothermal fields and diamictites in the Barberton greenstone belt - Paleoarchean crust in cold environments.Science Advance AEON and Earth Stewardship Science Research Institute, Nelson Mandela Metropolitan Univerisity, 13p.TechnologyGlacial remnants, exosphere, silica pipes

Abstract: Estimates of ocean temperatures on Earth 3.5 billion years ago (Ga) range between 26° and 85°C. We present new data from 3.47- to 3.43-Ga volcanic rocks and cherts in South Africa suggesting that these temperatures reflect mixing of hot hydrothermal fluids with cold marine and terrestrial waters. We describe fossil hydrothermal pipes that formed at ~200°C on the sea floor >2 km below sea level. This ocean floor was uplifted tectonically to sea level where a subaerial hydrothermal system was active at 30° to 270°C. We also describe shallow-water glacial diamictites and diagenetic sulfate mineral growth in abyssal muds. These new observations reveal that both hydrothermal systems operated in relatively cold environments and that Earth’s surface temperatures in the early Archean were similar to those in more recent times.
DS201611-2113
2016
de Wit, M.J.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.
DS201804-0707
2017
de Wit, M.J.Kidane, A.T., Koch-Muller, M., Wiedenbeck, M., de Wit, M.J.Tracking sources of selected diamonds from southern Africa based on carbon isotopic and chemical impurities. River Ranch, Swartruggens, Klipspringer, PremierSouth African Journal of Geology, Vol. 120, 3, pp. 371-384.Africa, Zimbabwe, South Africadiamond morphology

Abstract: The morphological, chemical impurities and carbon isotope properties of diamonds may reveal subtle details of their mantle source and growth characteristics, supporting efforts towards identifying their original place of harvesting. Here we investigate the mantle carbon and nitrogen sources and growth patterns from selected diamonds mined from four kimberlites: macro-sized diamonds from River Ranch kimberlite in Zimbabwe and the Swartruggens and Klipspringer kimberlitic deposits from South Africa, and micro-sized diamonds from the Klipspringer and Premier kimberlite intrusions in South Africa. Type IaAB diamonds are found in all the samples; Type IaB diamonds only occur in samples from the Swartruggens, River Ranch and Premier kimberlites. A single Type II diamond (nitrogen below the detection limit) was also observed in the River Ranch and Premier kimberlites. Both the micro- and macro-sized diamonds from Klipspringer have similar nitrogen contents. Based on the % B-defect, the diamonds from Klipspringer are grouped into low- and high-nitrogen aggregates (i.e. % of B-defect <40% and >56%, respectively) that likely represent two different diamond forming episodes. Time averaged mantle storage temperatures for Type IaAB diamonds are calculated to have been: 1060°C for Swartruggens; 1190°C for River Ranch; 1100°C (low aggregated); and 1170°C (highly aggregated) for Klipspringer, and 1210°C for Premier diamonds. The CL-images of the River Ranch, Klipspringer and Premier diamonds reveal multi-oscillatory growth zones. The carbon isotopic analyses on the diamonds reveal an average d13CVPDB value of: -4.5‰ for Swartruggens; -4.7‰ for River Ranch; -4.5‰ for Klipspringer; and -3‰ for Premier. With the exception of the diamond from Premier, the average d13C value of the diamonds are similar to the average d13C value of the mantle (-5‰), which is similar to the occurrence of diamonds in the other kimberlites. The internal carbon isotopic variation of individual diamonds from Swartruggens, Klipspringer and Premier are less than 4‰, which is similar to the variability of most other diamond occurrences reported from elsewhere in the world. Up to 6.7‰ internal carbon isotopic variation was observed in a single diamond from River Ranch. The internal carbon isotopic studies of the diamonds reveal that the primary carbon in the Swartruggens and Klipspringer was derived from an oxidation of CH4-bearing fluid, whereas in the River Ranch the primary carbon was derived from the reduction of carbonate-or CO2-bearing fluids. The Swartruggens diamonds also reveal a secondary carbon sourced from a reduction of CO2- or carbonate-rich fluid or melt. Diamonds from Klipspringer exhibit a cyclic change in d13C values that reflects fluctuation in a complex mantle perturbation system or periodic change in fugacity of the mantle. Based on this study, we conclude that, in principle, a selected range of diamond signatures might be used to fingerprint their origins; especially when linked to their other physical properties such as a low temperature magnetic signature.
DS200612-0322
2005
De Wit, M.J.C.De Wit, M.J.C., Thiart, C.Metallogenic fingerprints of Archean Cratons.Geological Society of London Special Paper, No. 248, pp. 59-70.GlobalMetallogeny
DS201509-0393
2015
De Wit, R.W.L.De Wit, R.W.L., Trampert, J.Robust constraints on average radial lower mantle anisotropy and consequences for composition and texture.Earth and Planetary Science Letters, Vol. 429, pp. 101-109.MantleSeismic -anisotropy

Abstract: The seismic structure of Earth’s inner core is highly complex, displaying strong anisotropy and further regional variations. However, few seismic waves are sensitive to the inner core and fundamental questions regarding the origin of the observed seismic features remain unanswered. Thus, newtechniques to observe different types of inner corewaves are imperative to improve data coverage. Here, we detail our method for detecting exotic inner core phases such as PKJKP and PKIIKP, using inner core compressional waves as proof of concept.We use phase weighted stacking on long period data from a global distribution of stations, and employ several synthetic methods, including normal mode summation and SPECFEM, to identify and confirm the inner core phases. We present evidence for two observations of exotic inner core compressional waves, and apply the technique to a previously detected inner core shear wave. A possible new inner core shear wave remains unconfirmed. Additionally, we show how our method is important for rejecting potential observations, and distinguishing between waves with similar traveltime and slowness. The method is most successful for detecting exotic inner core compressional waves, and will provide a new approach for studying the compressional wave structures in the upper inner core.
DS1995-0408
1995
De Witt, M.C.J.De Witt, M.C.J.On the relationship of post Gondwana River systems and alluvial diamonds in western South Africa.Exploration and Mining Geology, Vol. 4, No. 1, p. 85.South AfricaPlacers, alluvials, Paleogeomorphology
DS200412-0432
2004
De Zeeuw van Dalfsen, E.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
DS1996-0353
1996
Deacon, G.L.Deacon, G.L.Paleofluvial channels in the Joseph Bonaparte Gulf of interest to diamondexploration.Geological Society of Australia 13th. Convention held Feb., No. 41, abstracts p.108.AustraliaAlluvials, Joseph Bonaparte Gulf area
DS201511-1833
2014
Deacon, G.L.Downes, P.J., Bevan, A.W.R., Deacon, G.L.The Kimberley Diamond Company Ellendale diamond collection at the Western Australia Museum.Australian Gemmologist, Vol. 24, 12, pp. 289-293.AustraliaDeposit - Ellendale
DS1988-0163
1988
Deacon, J.Deacon, J., Lancaster, N.Late Quaternary Paleoenvironments of southern AfricaOxford University of Press, 236p. APPROX. $65.00USSouth AfricaPaleogeography
DS201709-1992
2017
Deady, E.Goodenough, K.M., Shaw, R., Deady, E.Interaction of alkaline magmatism and carbonatites: a recipe for REE enrichment?Goldschmidt Conference, abstract 1p.Mantlecarbonatites

Abstract: The rare earth elements (REE) are critical metals that have been the subject of considerable recent research. In the published literature, REE deposits are typically divided into classes, which commonly include ‘alkaline igneous rocks’ and ‘carbonatites’ [1]. However, our recent work, carried out as part of the EURARE and HiTech AlkCarb projects, suggests that many deposits of the REE and other critical metals may be formed where late-stage carbonatites and associated fluids interact with alkaline igneous rocks. A key question is whether these carbonatites are formed by liquid immiscibility from the host alkaline magmas, or whether they are introduced from other sources. A classic example of a mineral deposit formed in this way is at Ivigtut in Greenland, where late-stage F and CO2 rich fluids interacted with alkali granitic melts to form a cryolite (Na3AlF6) deposit, with associated metasomatism and REE mobilisation. Isotopic evidence indicates that these late-stage fluids may have been carbonatite-derived [2]. Our more recent work indicates that REE enrichment in many alkaline igneous complexes may be generated by a similar mechanism. In the alkaline igneous province of NW Scotland, late-stage metasomatism by CO2-rich fluids has generated metasomatised veins with TREO up to 2 wt% [3]. Similar features are observed in the Ditrau Alkaline Igneous complex in Romania, where REE mineralisation is represented by monazite- and carbonate-rich veins cutting syenitic host rocks [4]; and at the Kizilcaören REE deposit in Turkey. This talk will provide an overview of the formation of REE mineralisation in this type of magmatic-hydrothermal system and consider future research questions.
DS201802-0233
2018
Deady, E.Elliott, H.A.L., Wall, F., Chakmouradian, A.R., Siegfried, P.R., Dahlgren, S., Weatherley, S., Finch, A.A., Marks, M.A.W., Dowman, E., Deady, E.Fenites associated with carbonatite complexes: a review.Ore Geology Reviews, Vol. 92, pp. 38-59.Globalcarbonatites

Abstract: Carbonatites and alkaline-silicate rocks are the most important sources of rare earth elements (REE) and niobium (Nb), both of which are metals imperative to technological advancement and associated with high risks of supply interruption. Cooling and crystallizing carbonatitic and alkaline melts expel multiple pulses of alkali-rich aqueous fluids which metasomatize the surrounding country rocks, forming fenites during a process called fenitization. These alkalis and volatiles are original constituents of the magma that are not recorded in the carbonatite rock, and therefore fenites should not be dismissed during the description of a carbonatite system. This paper reviews the existing literature, focusing on 17 worldwide carbonatite complexes whose attributes are used to discuss the main features and processes of fenitization. Although many attempts have been made in the literature to categorize and name fenites, it is recommended that the IUGS metamorphic nomenclature be used to describe predominant mineralogy and textures. Complexing anions greatly enhance the solubility of REE and Nb in these fenitizing fluids, mobilizing them into the surrounding country rock, and precipitating REE- and Nb-enriched micro-mineral assemblages. As such, fenites have significant potential to be used as an exploration tool to find mineralized intrusions in a similar way alteration patterns are used in other ore systems, such as porphyry copper deposits. Strong trends have been identified between the presence of more complex veining textures, mineralogy and brecciation in fenites with intermediate stage Nb-enriched and later stage REE-enriched magmas. However, compiling this evidence has also highlighted large gaps in the literature relating to fenitization. These need to be addressed before fenite can be used as a comprehensive and effective exploration tool.
DS201906-1330
2019
Deady, E.Nex, P.A.M., Deady, E.Have the wheels fallen off your 'hype cycle'? A retrospective look at criticality: tantalum, rare earth elements and lithium.3rd International Critical Metals Meeting held Edinburgh, 1p.abstract p. 42.GlobalREE

Abstract: Link to presentation pdf.
DS201412-0305
2014
Deady, E.A.Goodenough, K.M., Deady, E.A., Shaw, R.A.The potential for REE deposits associated with alkaline and carbonatitic magmatism in Europe.30th. International Conference on Ore Potential of alkaline, kimberlite and carbonatite magmatism. Sept. 29-, http://alkaline2014.comEuropeCarbonatite
DS201809-2032
2018
Deady, E.A.Gunn, A.G., Dorbor, J.K., Mankelow, J.M., Lusty, P.A.J., Deady, E.A., Shaw, R.A.A review of the mineral potential of Liberia.Ore Geology Reviews, Vol. 101, pp. 413-431.Africa, Liberiadiamonds

Abstract: The Republic of Liberia in West Africa is underlain mostly by Precambrian rocks of Archaean (Liberian) age in the west and of Proterozoic (Eburnean) age in the east. By analogy with similar terranes elsewhere in the world, and in West Africa in particular, the geology of Liberia is favourable for the occurrence of deposits of a wide range of metals and industrial minerals, including gold, iron ore, diamonds, base metals, bauxite, manganese, fluorspar, kyanite and phosphate. Known gold deposits, mostly orogenic in style, occur widely and are commonly associated with north-east-trending regional shear zones. Gold mining commenced at the New Liberty deposit in western Liberia in 2015, while significant gold resources have also been identified at several other sites in both Archaean and Proterozoic terranes. Liberia has large resources of itabirite-type iron ores, most of which are located in the Liberian terrane, and was the largest producer in Africa prior to the onset of civil war in 1989. Production of iron ore is currently restricted to a single mine, Yekepa, in the Nimba Range. Other important deposits, some of them previously mined, include Bong, the Western Cluster, Putu and Goe Fantro. There is a long history of alluvial diamond production in western and central Liberia, together with more than 160 known occurrences of kimberlite. Most of the known kimberlites occur in three clusters of small pipes and abundant dykes, located at Kumgbor, Mano Godua and Weasua, close to the border with Sierra Leone. Many of these are considered to be part of a single province that includes Jurassic age diamondiferous kimberlites in Sierra Leone and Guinea. Deposits and occurrences of a wide range of other metals and industrial minerals are also known. Several of these have been worked on a small scale in the past, mainly by artisanal miners, but most are poorly known in detail with sub-surface information available at only a few localities. By comparison with most other countries in West Africa, the geology of Liberia is poorly known and there has been very little systematic exploration carried out for most commodities other than gold, iron ore and diamonds since the 1960s and 1970s. Further detailed field and laboratory investigations using modern techniques are required to properly evaluate the potential for the occurrence of economic deposits of many minerals and metals in a variety of geological settings. Digital geological, geochemical, geophysical and mineral occurrence datasets, including new national airborne geophysical survey data, provide a sound basis for the identification of new exploration targets, but in almost every part of the country there is a need for new and more detailed geological surveys to underpin mineral exploration.
DS201906-1270
2019
Deady, E.A.Barnett, M.J., Deady, E.A., Gregory, S.P., Palumbo-Roe, B.The role of biobased circular economy approach in sustainable critical metal extraction: the rare earth elements. Bioleaching3rd International Critical Metals Meeting held Edinburgh, Apr. 30-May 2.GlobalREE

Abstract: PDF link to presentation.
DS201906-1273
2019
Deady, E.A.Beard, C.D., Goodenough, K.M., Deady, E.A.Deposit scale geomodels for REE and HFSE exploration in carbonatite and alkaline silicate magmatic systems.3rd International Critical Metals Meeting held Edinburgh, 1p.abstract p. 39.GlobalREE

Abstract: PDF link to presentation.
DS201909-2021
2019
Deady, E.A.Beard, C.D., Goodenough, K.M., Broom-Findlay, S., Borst, A.M., Roberts, N.M.W., Finch, A.A., Deady, E.A.Subducted sediments as a source of REE in mineralized post - collisional alkaline carbonatite systems.Goldschmidt2019, 1p. AbstractChinasubduction

Abstract: Many of the world's largest known REE deposits are associated with post-collisional alkaline-carbonatite magmatic complexes (e.g., the Minanning-Dechang belt, China). These systems are potassic to ultrapotassic in composition and contain LREE-dominated mineralisation associated with F and Ba-rich carbonatite breccias, carbonatite dykes and carbo-hydrothermal veins. They are typically emplaced through major shear zones during a period of 'relaxation' that postdates continental collision by up to 75 Ma. The subduction of sediment during continental collision is potentially a key control on the 'fertility' of the mantle source, and understanding the role of sediment is a crucial step towards better exploration models. However, the identification of sediment source components to alkaline systems has not been straightforward because their petrological complexity precludes traditional methods such as trace-element ratios and major-element modelling of crystal fractionation. We use a global database of Sr, Nd and Hf isotope compositions for alkaline and carbonatite systems, alongside geodynamic reconstructions to identify favourable source components for mineralisation and to provide direct information about the origin of the metals of interest. Subduction of shale and carbonate sequences is likely to introduce REE + HFSE and potentially mineralising ligands (F-, CO3 2-) into the mantle source for post-collisional alkaline systems; clastic sediments are poorer in these vital components. This research provides a framework through which the mineral exploration industry can identify tectonic environments that are predisposed to form REE mineralisation, providing regional-scale (100-1000 km) guidance especially for systems hidden beneath sedimentary cover.
DS1986-0173
1986
Deakin, A.S.Deakin, A.S., Boxer, G.L.The Argyle AKl diamond size distribution: the use of fine diamonds to predict the occurrence of commercial size diamondsProceedings of the Fourth International Kimberlite Conference, Held Perth, Australia, No. 16, pp. 448-450AustraliaDiamond exploration
DS1986-0174
1986
Deakin, A.S.Deakin, A.S., Boxer, G.L., Meakins, A.E., Haebig, E., Lew, J.H.Geology of the Argyle alluvial diamond deposits #1Proceedings of the Fourth International Kimberlite Conference, Held, No. 16, pp. 451-453AustraliaDiamond exploration
DS1989-0344
1989
Deakin, A.S.Deakin, A.S., Boxer, G.L.Argyle AK1 diamond size distribution: the use of fine diamonds to predict the occurrence of commercial sizediamondsGeological Society of Australia Inc. Blackwell Scientific Publishing, Special, No. 14, Vol. 2, pp. 1117-1122AustraliaDiamond distribution, Deposit -Argyle
DS1989-0345
1989
Deakin, A.S.Deakin, A.S., Boxer, G.L., Meakins, A.E., Haebig, A.E., Lew, J.H.Geology of the Argyle alluvial diamond deposits #2Geological Society of Australia Inc. Blackwell Scientific Publishing, No. 14, Vol. 2, pp. 1108-1116AustraliaAlluvial-placers, Deposit -Argyle
DS1990-0231
1990
Deakin, A.S.Boxer, G.L., Deakin, A.S.Argyle alluvial depositsIn: Geology of the Mineral Deposits of Australia and Papua New Guinea ed., Vol. 2, pp. 1655-1658AustraliaAlluvials, Deposit -Argyle
DS1991-0359
1991
Deakin, A.S.Deakin, A.S., White, S.H.Shear zone control of alkali intrusives -examples from Argyle and WestAfricaProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 71-73Australia, Sierra LeoneArgyle, Yengema, Lissadell, Lineaments, tectonics
DS1994-0414
1994
Deakin, A.S.Deakin, A.S., White, S.H.Shear zone control of alkali intrusives: examples from Argyle, northwestern Australia and Yengema, Sierra Leone, West Africa.Proceedings of Fifth International Kimberlite Conference, Vol. 2, pp. 251-258.Sierra LeoneAlkaline rocks
DS1993-1791
1993
Deakin, S.Yates, D., Matthews, D., Deakin, S.Hard rock diamond mining at Argyle Diamond Mines Pty. LtdAustralia Min. Met. Mawby Memorial Volume, Mon. 19, pp. 1443-1448.AustraliaMining, Deposit -Argyle
DS1993-1792
1993
Deakin, S.Yates, D., Matthews, D., Deakin, S.Open pit mining at Argyle diamond mine, western AustraliaThe Canadian Mining and Metallurgical Bulletin (CIM Bulletin) , Annual Meeting Abstracts LESS than approximately 10, Vol. 86, No. 968, March ABSTRACT p. 75.AustraliaMining, Mineral processing, Deposit -Argyle
DS2002-0368
2002
Deakin, S.Deakin, S.The use of microdiamonds in grade estimationProspectors and Developers Association of Canada (PDAC) 2002, 1p. abstractGlobalMicrodiamonds
DS201902-0267
2019
Deales, J.Deales, J., Lenardic, A., Moore, W.Assessing the intrinsic uncertainty and structural stability of planetary models: 1) parameterized thermal/tectonic history models.Researchgate preprint, 21p. Pdf availableMantlegeothermometry

Abstract: Thermal history models, that have been used to understand the geological history of Earth, are now being coupled to climate models to map conditions that allow planets to maintain surface water over geologic time - a criteria considered crucial for life. However, the lack of intrinsic uncertainty assessment has blurred guidelines for how thermal history models can be used toward this end. A model, as a representation of something real, is not expected to be complete. Unmodeled effects are assumed to be small enough that the model maintains utility for the issue(s) it was designed to address. The degree to which this holds depends on how unmodeled factors affect the certainty of model predictions. We quantify this intrinsic uncertainty for several parameterized thermal history models (a widely used subclass of planetary models). Single perturbation analysis is used to determine the reactance time of different models. This provides a metric for how long it takes low amplitude, unmodeled effects to decay or grow. Reactance time is shown to scale inversely with the strength of the dominant feedback (negative or positive) within a model. A perturbed physics analysis is then used to determine uncertainty shadows for model outputs. This provides probability distributions for model predictions and tests the structural stability of a model. That is, do model predictions remain qualitatively similar, and within assumed model limits, in the face of intrinsic uncertainty. Once intrinsic uncertainty is accounted for, model outputs/predictions and comparisons to observational data should be treated in a probabilistic way.
DS201312-0270
2013
Dean, B.Flemming, R.L., Weiss, T.L.C., Dean, B.Quantifying strain related mosaicity in mantle olivine by uXRD: examples from kimberlites and mantle xenoliths.GAC-MAC 2013 SS4: from birth to the mantle emplacement in kimberlite., abstract onlyMantleOlivine
DS201212-0798
2012
Deane, J.A.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
DS201610-1868
2016
Deangelis, M.T.Harper, D.R., Deangelis, M.T.Examination of mica bearing rocks from the Magnet Cove alkaline intrusive complex, Arkansas.GSA Annual Meeting, 1/2p. abstractUnited States, ArkansasIjolite, carbonatite

Abstract: The Magnet Cove Alkaline Intrusive Complex contains several silica-undersaturated igneous rock types (e.g. nepheline syenite, ijolite, carbonatite) that form a concentric ring map pattern approximately 4.6 square miles in area. These rings, which are likely the result of several nearly contemporaneous magma injection events during the mid Cretaceous, become increasingly silica-undersaturated from rim to core, and have been previously mapped as separate geologic units. The outer ring contains nepheline syenite, the intermediate ring contains both garnet ijolite and garnet biotite ijolite, and the core contains carbonatite. Though the detailed modal mineralogy differs somewhat between the silicate (i.e. syenite and ijolite) rock types, they all have in common the presence of mica group minerals. The purpose of this study is to examine and characterize the diversity of mica group minerals found in the silica-undersaturated rocks of Magnet Cove. Syenite and ijolite rock samples were collected from several locations within the complex, and thin sections were prepared for petrographic and electron microscope analysis using facilities and equipment at the UALR Rock Preparation Laboratory. Overall mineralogy from these samples indicates the presence of potassium feldspar, plagioclase feldspar, several feldspathoid minerals (nepheline, sodalite, altered leucite), amphiboles, pyroxenes (primarily aegerine and aegerine-augite), black Ti-bearing garnets (melanite, schorlomite), and various opaque minerals (e.g. magnetite, pyrite). Previously, micas in these rocks have been labeled simply as “biotite”. However, the ranges of color (yellowish-brown to bluish-green), crystal size (millimeter to several centimeters in diameter), and crystal habit (clusters of euhedral grains) in hand sample and variable pleochroism, ranging interference colors, reaction coronas, and zoning in thin section indicate a more interesting and complex chemical history.
DS200812-1103
2008
DeAngelsi, M.Spetsius, Z.V., Taylor, L.A., Valley, J.W., DeAngelsi, M., Spicuzza, M., Ivanov, A.S., Banzeruk, V.I.Diamondiferous xenoliths from crustal subduction: garnet oxygen isotopes from the Nyurbinskaya pipe, Yakutia.European Journal of Mineralogy, Vol. 20, no. 3, pp. 375-385.Russia, YakutiaDeposit - Nyurbinskaya
DS1983-0195
1983
Deans, A.Deans, A.Diamonds; Alexander and Hattersley's Australian Mining, 1983In: Alexander And Hattersley's Australian Mining, Minerals A, PP. 31-32.Australia, Western AustraliaCurrent Activities, Kimberley
DS1960-0510
1965
Deans, T.Allen, J.B., Deans, T.Ultrabasic Eruptives with Alnoitic Kimberlitic Affinities from Malaita solomon Islands.Mineralogical Magazine., Vol. 34, TILLEY VOLUME, PP. 16-34.GlobalRelated Rocks, Indicator Minerals, Mineralogy
DS1960-0651
1966
Deans, T.Deans, T.Economic Mineralogy of African CarbonatitesIn: Carbonatites, Tuttle, O.f.; Gittins, J. Editors, PP. 385-413.Southwest Africa, NamibiaKimberley, Carbonatite
DS1984-0223
1984
Deans, T.Deans, T., Roberts, B.Carbonatite Tuffs and Lava Clasts of the Tinderet Foothills, Western Kenya: a Study of Calcified Natrocarbonatites.Geological Society of London Journal, Vol. 141, PP. 563-580.Central Africa, KenyaRelated Rocks, Petrography
DS1984-0292
1984
Deans, T.Garson, M.S., Coats, J.S., Rock, N.M.S., Deans, T.Fenites, Breccia Dykes, Albitites and Carbonatitic Veins Near the Great Glen Fault, Inverness, Scotland.Journal of the Geological Society of London., Vol. 141, PP. 711-732.ScotlandRelated Rocks
DS1990-1121
1990
Deans, T.Notholt, A.J.G., Highley, D.E., Deans, T.Economic minerals in carbonatites and associated alkaline rocksTransactions of the Institute of Mining and Metallurgy (IMM), Vol. 99, Section B, May-August pp. B59-B80GlobalCarbonatite, Good review-economics
DS1994-0579
1994
Dearaujo, D.P.Gaspar, J.C., Silva, A.J.C.C., Dearaujo, D.P.Composition of priderite in phlogopites from the Catalao I carbonatitecomplex, Brasil.Mineralogical Magazine, Vol. 58, No. 392, Sept. 409-415.BrazilCarbonatite
DS1997-0262
1997
Dearden, P.Dearden, P.Environmental change and challenge - a Canadian perspectiveOxford University of Press, CanadaBook - ad, Environmental challenge
DS1984-0224
1984
Dearlove, J.P.L.Dearlove, J.P.L.Geology of the alkaline rocks in the Kirkland-Lake TimminsDistrictOntarioMsc. Thesis, University of Waterloo, 176pOntarioAlkaline Rocks
DS1995-0682
1995
DearnGriffin, B.J., Rissanen, J., Pooley, G.D., Lee, DearnA new Diamondiferous eclogite bearing kimberlitic occurrence from FinlandProceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 198-200.FinlandEclogite
DS201212-0616
2012
Deas, S.K.Sahu, N., Gupta, T., Patel, S.C.,Khuntia, D.B.K., Thakur, S.S., Deas, S.K.Petrology of lamproites from the Nuapada lamproite field, Bastar Craton, India.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractIndiaDeposit - Nuapada
DS2002-0280
2002
DebChaudhuri, A.K., Saha, Deb, Mukherjee, GhoshThe Purana basins of southern cratonic province of India - a case for mesoproterozoic fossil rifts.Gondwana Research, Vol. 5, No. 1, pp. 23-34.IndiaCraton - rifting, tectonics
DS201809-2047
2018
Deb, G.K.Joy, S., Van der Linde, G., Choudbury, A.K., Deb, G.K., Tappe, S.Reassembly of the Dharwar and Bastar cratons at ca. 1 Ga: evidence from multiple tectonothermal events along the Karimnagar granulite belt and Khammam schist belt, southern India.Journal of Earth System Science, Vol. 127, 6, pp. 76- doi:10.1007/s12040-018-0988-2Indiacratons

Abstract: The northern part of the Nellore-Khammam schist belt and the Karimnagar granulite belt, which are juxtaposed at high angle to each other have unique U-Pb zircon age records suggesting distinctive tectonothermal histories. Plate accretion and rifting in the eastern part of the Dharwar craton and between the Dharwar and Bastar craton indicate multiple and complex events from 2600 to 500 Ma. The Khammam schist belt, the Dharwar and the Bastar craton were joined together by the end of the Archaean. The Khammam schist belt had experienced additional tectonic events at ~1900 and ~1600 Ma. The Dharwar and Bastar cratons separated during development of the Pranhita-Godavari (P-G) valley basin at ~1600 Ma, potentially linked to the breakup of the Columbia supercontinent and were reassembled during the Mesoproterozoic at about 1000 Ma. This amalgamation process in southern India could be associated with the formation of the Rodinia supercontinent. The Khammam schist belt and the Eastern Ghats mobile belt also show evidence for accretionary processes at around 500 Ma, which is interpreted as a record of Pan-African collisions during the Gondwana assembly. From then on, southern India, as is known today, formed an integral part of the Indian continent.
DS200812-0007
2008
Deb, M.Ahmad, T., Deb, M., Tarney, J., Raza, M.Proterozoic mafic volcanism in the Aravalli Delhi orogen, northwest India: geochemistry and tectonic framework.Journal of Geological Society of India, Vol. 72, 1, pp. 93-112.IndiaTectonics
DS201808-1738
2017
Deb, M.Deb, M., Sarkar, S.C.Minerals and allied natural resources and their sustainable development. Principles, perspectives with emphasis on the Indian scenario. Detailed Book reviewSpringer Nature , book review in Mineralium Deposita diamonds mentioned p. 6-7. of reviewIndiadiamonds

Abstract: Nonrenewable natural resources - metallic and non-metallic minerals, industrial rocks and energy resources (both organic and inorganic), have been treated in a holistic manner in this book, including two important resources (soil and water), not commonly covered in most books on this topic. For the uninitiated reader, an introductory chapter looks into some basic definitions as well as nature and characteristics of mineral deposits followed by a chapter on the different crustal processes that produce the various ore deposits in the endogenous and exogenous environments. The strength of the book lies in its critical treatment of the genetic processes of the mineral deposits, their classification and the geodynamic context of metallogeny, and coverage of sustainable development of mineral deposits with special reference to various socio-economic as well as regulatory and environmental issues that face the Indian mining industry today. The text is punctuated with examples of Indian deposits, balanced with classical deposits around the world, to cater to the interests of Indian students and the international readership. This is a book for advanced undergraduate and post-graduate students of Geology, Environmental Sciences and Natural Resource Management.
DS201012-0522
2009
Debaille, V.Murphy, D.T., Brandon, A.D., Debaille, V., Burgess, R., Ballentine, C.In search of a hidden long term isolated sub-chondritic 142 Nd 144Nd reservoir in the deep mantle: implications for the Nd isotope systematics of the Earth.Geochimica et Cosmochimica Acta, Vol. 74, 2, pp. 738-750.MantleGeochronology
DS201212-0558
2012
Debaille, V.Pivin, M., Debaille, V., Mattielli, N.,Demaiffe, D.Nd-Hf isotope systematics of megacrysts from the Mbuji-Mayi kimberlites, D.R. Congo: implications for the cratonic lithospheric mantle.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractAfrica, Democratic Republic of CongoDeposit - Mbuji-Mayi
DS201312-0202
2013
DeBaille, V.DeBaille, V., O'Neill, C., Brandon, A.D., Haenecour, P., Yin, Q-Z., Mattielli, N., Trieman, A.H.Stagnant lid tectonics in early Earth revealed bu 142 Nd variations in late Archean rocks.Earth and Planetary Science Letters, Vol. 373, pp. 83-92.MantleConvection
DS201312-0711
2013
Debaille, V.Pivin, M., Debaille, V., Mattielli, N.Nd-Hf isotope systematics of megacrysts from the Mbuji-Mayi kimberlites, D.R. Congo: evidence for a metasomatic origin related to kimberlite interaction with the cratonic lithosphere mantle.Proceedings of the 10th. International Kimberlite Conference, Vol. 1, Special Issue of the Journal of the Geological Society of India,, Vol. 1, pp. 123-136.Africa, Democratic Republic of CongoDeposit - Mbuji-Mayi
DS201412-0648
2013
Debaille, V.O'Neill, C., Debaille, V., Griffin, W.L.Deep earth recycling in the Hadean and constraints on surface tectonics.American Journal of Science, Vol. 313, Nov. pp. 912-932.MantleTectonics
DS201904-0727
2019
Debaille, V.Decree, S., Demaiffe, D., Tack, L., Nimpagaritse, G., De Paepe, P., Bouvais, P., Debaille, V.The Neoproterozoic Upper Ruvubu alkaline plutonic complex ( Burundi) revisited: large scale syntectonic emplacement, magmatic differentiation and late stage circulations of fluids.Precambrian Research, Vol. 325, pp. 150-171.Africa, Burundicarbonatite

Abstract: The Upper Ruvubu Alkaline Plutonic Complex (URAPC) in Burundi consists of three separate intrusions, each with a specific emplacement age and petrological composition. Three main units are recognized: an outer unit with silica-saturated plutonic rocks (from gabbro to granite), an inner unit with silica-undersaturated plutonic rocks (feldspathoidal syenite with subordinate feldspathoidal monzonite and ijolite) and a carbonatitic body in the subsoil, known by drilling. The URAPC is quite large in size (~24?km long and up to 10?km wide). It is considered to have been intruded syntectonically in an overall extensional context, thanks to the kilometric shear zones that accommodated its emplacement. Radiometric ages from literature range from 748 to 705?Ma and point to structurally-controlled magmatic differentiation followed by long-lived circulations of late-stage fluids postdating the emplacement of a part of the undersaturated rocks and the carbonatites. In the north-western part of the outer unit, gabbro likely has been emplaced at a deeper structural level than the granite, which represents a more apical structural level of emplacement. This petrological, geochemical and isotopic (Sr-Nd-Hf) study concentrates on the processes that generated the URAPC: (i) fractional crystallization, evidenced by the chemical evolution trends of the major and trace elements, and by marked P, Ti and Ba anomalies in the trace element patterns; (ii) crustal assimilation/contamination, as shown by the wide range of Nd isotope compositions and the general increase of the Sr isotope ratios with increasing SiO2 contents, and (iii) late-magmatic/hydrothermal alteration inducing an increase of the Sr isotope composition without changing significantly the Nd isotope composition. The isotopic data are consistent with an asthenospheric mantle source, though less depleted than the Depleted Mantle (DM), contaminated by the Subcontinental Lithospheric Mantle (SCLM). The silicate and carbonate magmatic series are cogenetic. The outer unit is clearly more contaminated than the inner unit, whereas the carbonatitic body could have evolved by liquid immiscibility. The URAPC lies within East Africa’s Western Rift Valley, which is marked by 23 alkaline plutonic complexes. Their emplacement has been ascribed to reactivation of Proterozoic lithospheric weakness zones resulting from the breakup of the Neoproterozoic supercontinent Rodinia supercontinent.
DS202101-0007
2020
Debaille, V.Decree, S., Savolainen, M., Mercadier, J., Debaille, V., Hohn, S., Frimmel, H., Baele, J-M.Geochemical and spectroscopic investigation of apatite in the Siilinjarvi carbonatite complex: keys to understanding apatite forming processes and assessing potential for rare earth elements.Applied Geochemistry, Vol. 123, 104778 17p. PdfEurope, Finlanddeposit - Siilinjarvi

Abstract: The Siilinjärvi phosphate deposit (Finland) is hosted by an Archean carbonatite complex. The main body is composed of glimmerite, carbonatite and combinations thereof. It is surrounded by a well-developed fenitization zone. Almost all the rocks pertaining to the glimmerite-carbonatite series are considered for exploitation of phosphate. New petrological and in-situ geochemical as well as spectroscopic data obtained by cathodoluminescence, Raman and laser-induced breakdown spectroscopy make it possible to constrain the genesis and evolution of apatite through time. Apatite in the glimmerite-carbonatite series formed by igneous processes. An increase in rare earth elements (REE) content during apatite deposition can be explained by re-equilibration of early apatite (via sub-solidus diffusion at the magmatic stage) with a fresh carbonatitic magma enriched in these elements. This late carbonatite emplacement has been known as a major contributor to the overall P and REE endowment of the system and is likely connected to fenitization and alkali-rich fluids. These fluids - enriched in REE - would have interacted with apatite in the fenite, resulting in an increase in REE content through coupled dissolution-reprecipitation processes. Finally, a marked decrease in LREE is observed in apatite hosted by fenite. It highlights the alteration of apatite by a REE-poor fluid during a late-magmatic/hydrothermal stage. Regarding the potential for REE exploitation, geochemical data combined with an estimation of the reserves indicate a sub-economic potential of REE to be exploited as by-products of phosphate mining. Spectroscopic analyses further provide helpful data for exploration, by determining the P and REE distribution and the enrichment in carbonatite and within apatite.
DS202001-0025
2019
Debajyoti, P.Kumari, S., Debajyoti, P., Stracke, A.Constraints on Archean crust formation from open system models of Earth evolution.Chemical Geology, doi.org/10.1016/ j.chemgeo.2019. 119307Mantlecraton

Abstract: Establishing the mode and rate of formation of the continental crust is crucial for quantifying mass exchange between Earth’s crust and mantle. The limited crustal rock record, particularly of early Archean rocks, has led to a variety of different models of continental growth. Here, we present an open-system model of silicate Earth evolution incorporating the Sm-Nd and Lu-Hf isotope systematics with the aim to constrain crustal growth during the Archean and its effect on the chemical and isotopic evolution of Earth’s crust-mantle system. Our model comprises four reservoirs: the bulk continental crust (CC), depleted upper mantle (UM), lower mantle (LM), and an isolated reservoir (IR) where recycled crust is stored transiently before being mixed with the LM. The changing abundance of isotope species in each reservoir is quantified using a series of first order linear differential equations that are solved numerically using the fourth order Runge-Kutta method at 1 Myr time steps for 4.56 Gyr (the age of the Earth). The model results show that only continuous and exponential crustal growth reproduces the present-day abundances and isotope ratios in the terrestrial reservoirs. Our preferred crustal growth model suggests that the mass of the CC by the end of Hadean (4.0 Ga) and end of Archean (2.5 Ga) was ~30% and ~75% of the present-day mass of the CC, respectively. Models proposing formation of most (~90%) of the present-day CC during the initial 1 Gyr or nearly 50-60% during the last 1 Gyr are least favorable. Significant mass exchange between crust and mantle, that is, both the formation and recycling of crust, started in the Hadean with Sm-Nd and Lu-Hf isotope evolution typical for mafic rocks. Depletion of the UM (in incompatible elements) during the early Archean is mitigated by the input of recycled crust, so that the UM maintained a near-primitive Hf-Nd isotope composition. The LM also retained a near-primitive Hf-Nd isotope composition during the Archean, but for different reasons. In contrast to the UM, the crustal return flux into the LM is transiently stored (~ 1 Gyr) in an isolated reservoir (IR), which limits the mass flux into and out of the LM. The IR in our model is distinct from other mantle reservoirs and possibly related to stable crustal blocks or, alternatively, to recycled crust in the mantle that remains temporarily isolated, perhaps at the core-mantle boundary (LLSVPs).
DS1997-0263
1997
DeBari, S.M.DeBari, S.M.Evolution of magmas in continental and oceanic arcs: the role of the lowercrust.Canadian Mineralogist, Vol. 35, No. 2, April pp. 501-520.Alaska, ArgentinaCrust, Mantle magma, Slab subduction
DS200812-0761
2007
DeBayleMontagner, 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
DS2000-0223
2000
Debayle, E.Debayle, E., Kennett, B.L.N.The Australian continental upper mantle: structure and deformation inferred from surface waves.Journal of Geophysical Research, Vol.105, No.11, Nov.10, pp.25423-50.AustraliaTectonics
DS2000-0224
2000
DeBayle, E.DeBayle, E., Kennett, B.L.N.Anisotropy in the Australasian upper mantle from Love and Rayleigh waveform inversion.Earth and Planetary Science Letters, Vol. 184, No.1, Dec.30, pp.339-51.AustraliaTomography - geophysics, seismics
DS2001-0240
2001
DeBayle, E.DeBayle, E., Leveque, J.J., Cara, M.Seismic evidence for deeply rooted low velocity anomaly in upper mantle beneath NE Afro Arabian continent.Earth and Planetary Science Letters, Vol. 193, No. 3-4, pp. 423-36.Mantle, ArabiaGeophysics - seismics, Plume - tomography, Afar Depression
DS200412-0434
2004
DeBayle, E.DeBayle, E., Kennett, B.L.N.Surface wave studies of the Australian region.Hillis, R.R., Muller, R.D. Evolution and dynamics of the Australian Plate, Geological Society America Memoir, No. 372, pp. 25-40.AustraliaGeophysics - seismics
DS200512-0859
2005
Debayle, E.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
DS200512-0860
2004
Debayle, E.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
DS200612-1110
2006
Debayle, E.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
DS200612-1112
2006
Debayle, E.Priestly, K., McKenzie, D., Debayle, E.The state of the upper mantle beneath southern Africa.Tectonophysics, Vol. 416, 1-4, April 5, pp. 101-112.Africa, South Africa, BotswanaGeophysics - seismics
DS200712-1072
2007
Debayle, E.Tauszin, B., Debayle, E., Wittlinger, G.Constraints on the mantle transition zone structure from P-to-Sv converted waves.mantleplumes.org, 13p.MantleGeophysics - seismics, geothermometry
DS200812-0924
2008
Debayle, E.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
DS200812-1156
2008
Debayle, E.Tauzin, B., Debayle, E., Wiitinger, G.The mantle transition zone as seen by global Pds phases: no clear evidence for a thin transition zone beneath hotspots.Journal of Geophysical Research, Vol. 113, B8309.MantleHotspots
DS201012-0780
2010
Debayle, E.Tauzin, B., Debayle, E., Wittlinger, G.Seismic evidence for a global low-velocity layer within the Earth's upper mantle.Nature Geoscience, Vol. 3, Oct. pp. 718-721.MantleGeophysics - seismics
DS201212-0157
2012
DeBayle, E.DeBayle, E., Ricard, Y.A global shear veolocity model of the upper mantle from fundamental and higher Rayleigh mode measurements.Journal of Geophysical Research, Vol. 117, B10, B 10308.MantleGeophysics - seismics
DS201801-0009
2017
Debayle, E.Coltice, N., Larrouturou, G., Debayle, E., Garnero, E.J.Interactions of scales of convection in the Earth's mantle.Tectonophysics, in press available, 9p.Mantleplate tectonics, geophysics - seismics

Abstract: The existence of undulations of the geoid, gravity and bathymetry in ocean basins, as well as anomalies in heat flow, point to the existence of small scale convection beneath tectonic plates. The instabilities that could develop at the base of the lithosphere are sufficiently small scale (< 500 km) that they remain mostly elusive from seismic detection. We take advantage of 3D spherical numerical geodynamic models displaying plate-like behavior to study the interaction between large-scale flow and small-scale convection. We find that finger-shaped instabilities develop at seafloor ages > 60 Ma. They form networks that are shaped by the plate evolution, slabs, plumes and the geometry of continental boundaries. Plumes impacting the boundary layer from below have a particular influence through rejuvenating the thermal lithosphere. They create a wake in which new instabilities form downstream. These wakes form channels that are about 1000 km wide, and thus are possibly detectable by seismic tomography. Beneath fast plates, cold sinking instabilities are tilted in the direction opposite to plate motion, while they sink vertically for slow plates. These instabilities are too small to be detected by usual seismic methods, since they are about 200 km in lateral scale. However, this preferred orientation of instabilities below fast plates could produce a pattern of large-scale azimuthal anisotropy consistent with both plate motions and the large scale organisation of azimuthal anisotropy obtained from recent surface wave models.
DS201901-0020
2018
Debayle, E.Coltice, N., Larrouturou, G., Debayle, E., Garnero, E.J.Interactions of scales of convection in the Earth's mantle.Tectonophysics, Vol. 746, pp. 669-677.Mantleconvection

Abstract: The existence of undulations of the geoid, gravity and bathymetry in ocean basins, as well as anomalies in heat flow, point to the existence of small scale convection beneath tectonic plates. The instabilities that could develop at the base of the lithosphere are sufficiently small scale (< 500 km) that they remain mostly elusive from seismic detection. We take advantage of 3D spherical numerical geodynamic models displaying plate-like behavior to study the interaction between large-scale flow and small-scale convection. We find that finger-shaped instabilities develop at seafloor ages > 60 Ma. They form networks that are shaped by the plate evolution, slabs, plumes and the geometry of continental boundaries. Plumes impacting the boundary layer from below have a particular influence through rejuvenating the thermal lithosphere. They create a wake in which new instabilities form downstream. These wakes form channels that are about 1000 km wide, and thus are possibly detectable by seismic tomography. Beneath fast plates, cold sinking instabilities are tilted in the direction opposite to plate motion, while they sink vertically for slow plates. These instabilities are too small to be detected by usual seismic methods, since they are about 200 km in lateral scale. However, this preferred orientation of instabilities below fast plates could produce a pattern of large-scale azimuthal anisotropy consistent with both plate motions and the large scale organisation of azimuthal anisotropy obtained from recent surface wave models.
DS1986-0175
1986
Debeaux, M.Debeaux, M., Durand-Wackenheim, C., Thiebaut, J.Cortlandite, monchiquite and ophites in the vicinity of the Job Springs, Haute-Garonne, France.(in French)Bulletin. de la Soc. d'Histoire Naturelle de Toulouse, Vol. 122, pp. 79-86FranceMonchiquite, Geochemistry
DS200612-0954
2006
Debecdelievre, A.Mungall, J.E., Hanley, J.J., Arndt, N.T., Debecdelievre, A.Evidence from meimechites and other low degree mantle melts for redox controls on mantle crust fractionation of platinum group elements.Proceedings of National Academy of Science USA, Vol. 103, 34, pp. 12695-12700.MantleMeimechite, PGE
DS201412-0671
2014
Debeuf, D.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
DS1996-0354
1996
Debicki, E.J.Debicki, E.J.MITEC's exploration technology Division: helping reverse the trend of declining mineral reserves in CanThe Canadian Mining and Metallurgical Bulletin (CIM Bulletin), Vol. 89, No. 997, Feb. pp. 53-59CanadaEconomics, MITEC.
DS2001-1146
2001
DeblondTack, L., Wingate, Liegeois, FernandesAlonzo, DeblondEarly Neoproterozoic magmatism ( 1000-910 Ma) of Zadinian and Mayumbian Groups.. onset Rodinia riftingPrecambrian Research, Vol. 110, No. ER1-4, pp. 277-306.East AfricaCraton - Congo, Magmatism
DS1988-0164
1988
Debon, F.Debon, F., Le Fort, P.A cationic classification of common plutonic rocks and theirmagmaticassociations: principles, method, applicationsBulletin de Mineralogie, No. 5, pp. 493-510. english Database # 17339GlobalRock Classification, Plutonic rocks
DS1980-0105
1980
Deboorder, H.Deboorder, H.Deep Reaching Fracture Zones in the Crystalline Basement Surrounding the West Congo System and Their Control of Mineralization in Angola and Gabon. #1Proceedings of the 26th International Geological Congress HELD French Geological Survey (BRGM), Proceedings Vol. 2, P. 713. (abstract.)Angola, Gabon, West AfricaTectonics
DS201610-1859
2016
Debouage, W.Doucet, L.S., Mattielli, N., Ionov, D.A., Debouage, W., Golovin A.V.Zn isotopic heterogeneity in the mantle: a melting control?Earth and Planetary Science Letters, Vol. 451, pp. 232-240.MantlePeridotite

Abstract: We present new Zn elemental and isotope data on seventeen fertile and refractory mantle peridotite xenoliths. Eleven fertile peridotites are garnet and spinel lherzolites from Vitim and Tariat (Siberia and Mongolia) and represent some of the most pristine fertile peridotites available. Six refractory peridotites are spinel harzburgites from the Udachnaya kimberlite (Siberian craton) that are nearly pristine residues of high-degree polybaric melting at high pressure (7-4 GPa). Geochemical data suggest that Zn isotopic compositions in the peridotites have not been affected by post-melting processes such as metasomatism, contamination by the host-magmas or alteration. The fertile peridotites have uniform Zn concentrations (59±2 ppm59±2 ppm) and Zn isotopic compositions with d66Zn (relative to JMC-Lyon-03-0749l)?=?+0.30?±?0.03‰ consistent with the Bulk Silicate Earth estimates of d66Zn?=?+0.28?±?0.05‰ (Chen et al., 2013). The refractory peridotites have Zn concentrations ranging from 30 to 48 ppm and d66Zn from +0.10±0.01‰+0.10±0.01‰ to +0.18±0.01‰+0.18±0.01‰ with an average of +0.14±0.03‰+0.14±0.03‰. Our data suggest that the lithospheric mantle has a heterogeneous Zn isotopic composition. Modeling of Zn isotope partitioning during partial melting of fertile mantle suggests that high degrees of melt extraction (>30%) may significantly fractionate Zn isotopes (up to 0.16‰) and that during mantle melting, Zn concentrations and isotopic compositions are mainly controlled by the stability of clinopyroxene and garnet within the melting residue. Because the stability of clinopyroxene and garnet is mainly pressure dependent we suggest that both the depth and the degrees of melt extraction may control Zn isotope fractionation during mantle melting.
DS201912-2790
2019
Debret, M.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?µm 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.
DS1991-0360
1991
Decaprona, G.C.Decaprona, G.C., Mascle, J.The Western Ivory Coast margin - result of an intra-continentalshearing.(in French)Comptes Rendus de l'Academie des Sciences Series II, (in French), Vol. 312, No. 13, June 20, pp. 1565-1572GlobalStructure, Tectonics
DS2002-0789
2002
DeCarli, P.S.Jones, A.P., Price, G.D., rice, N.J., DeCarli, P.S., Clegg, R.A.Impact induced melting and the development of large igneous provincesEarth and Planetary Science Letters, Vol. 202, 3-4, pp. 551-61.GlobalMagmatism - not specific to diamonds
DS201412-0460
2014
DeCarli, P.S.Kinzie, C.R., Que Hee, S.S., Stich, A., Tague, K.A., Mercer, C., Razink, J.J., Kennett, D.J., DeCarli, P.S., Bunch, T.E., Wittke, J.H., Israde-Alcantara, I., Bischoff, J.L., Goodyear, A.C., Tankersley, K.B., Kimbel, D.R., Culleton, B.J., Erlandson, J.M.Nanodiamond rich layer across three continents consistent with major cosmic impact at 12,800 Cal BP Journal of Geology, Vol 122, 5, pp. 475-506.Global, GreenlandNanodiamonds
DS201502-0069
2014
DeCarli, P.S.Kinzie, C.R., Que Hee, S.S., Stich, A., Tague, K.A., Mercer, C., Razink, J.J., Kennett, D.J., DeCarli, P.S., Bunch, T.E., Wittke, J.H., Israde-Alantara, I., Bischoff, J.L., Goodyear, A.C., Tankersley, K.B., Kimbel, D.R., Culleton, B.J., Erlandson, J.M.Nanodiamond-rich layer across three continents consistent with major cosmic impact at 12,800 Cal BP.Journal of Geology, Vol. 122, Sept. pp. 475-506.South America, BrazilNanodiamonds
DS1930-0135
1933
Decaters, C.Decaters, C.Champs et Mines de Diamant En Afrique du SudNature (paris), No. 2896, PP. 14-20.South AfricaDiamond Fields, Occurrences
DS1997-1234
1997
Dechen, S.Weipung, T., Dechen, S.Nonmetallic mineral deposits in ChinaProceedings 30th. IGC., Vol. 9, pp. 291-299ChinaIndustrial minerals
DS1981-0133
1981
Dechnow and Co. Pty. LtdDechnow and Co. Pty. LtdMc 04/6193 to Mc 04/6197 Diamond Exploration in the West Kimberley Lennard River and Noonkanbah Sheets.Western Australia Geological Survey, No. GSWA 1293 ROLL 417- M2868, 16P.Australia, Western AustraliaProspecting, Drilling
DS1989-1342
1989
DeckerSass, J.H., Blackwell, D.D., Chapman, D.S., Costain, J.K., DeckerHeat flow from the crust of the United StatesPhysical Properties of Rocks and Minerals, Ed. Y.S. Touloukian, W.R., ISBN 0-89116-883-4 $ 95.00 548p. pp. 503-GlobalHeat flow, Mantle
DS1991-0361
1991
Decker, .B.Decker, R., Decker, .B.Mountains of fire. The nature of volcanoesCambridge University Press, 226pGlobalVolcanoes, Book -ad
DS1996-0027
1996
Decker, D.T.Anderson, D.N., Decker, D.T., Valladares, C.E.Modeling boundary blobs using time varying invectionGeophys. Research Letters, Vol. 23, No. 5, March 1, pp 579-582MantleGeophysics -seismics, Boundary
DS1991-0361
1991
Decker, R.Decker, R., Decker, .B.Mountains of fire. The nature of volcanoesCambridge University Press, 226pGlobalVolcanoes, Book -ad
DS1997-0492
1997
DeConto, R.M.Hay, W.W., DeConto, R.M., Wold, Ch.M.Climate: is the past the key to the future?Geologische Rundschau, Vol. 86, No. 2, pp. 471-GlobalClimate
DS201312-0090
2013
Decree, S.Boulvais, P., Decree, S., Cobert, C., Midende, G., Tack, L., Gardien, V., Demaiffe, D.C and O isotope compositios of the Matongo carbonatite ( Burundi): new insights into alteration and REE mineralization processes.Goldschmidt 2013, AbstractAfrica, BurundiCarbonatite
DS201412-0575
2014
Decree, S.Midende, G., Boulais, P., Tack, L., Melcher, F., Gerdes,A., Dewaele, S., Demaiffe, D., Decree, S.Petrography, geochemistry and U Pb zircon age of the Matongo carbonatite Massif ( Burundi): implication for the Neoproterozoic geodynamic evolution of Central Africa.Journal of African Earth Sciences, Vol. 100, pp. 656-674.Africa, BurundiCarbonatite
DS201502-0078
2014
Decree, S.Midende, G., Boulvais, P., Tack, L., Melcher, F., Gerdes, A., Dewaele, S., Demaiffe, D., Decree, S.Petrography, geochemistry and U-Pb zircon age of the Matongo carbonatite Massif ( Burundi): implication for the Neoproterozoic geodynamic evolution of Central Africa.Journal of African Earth Sciences, Vol. 100, pp. 656-674.Africa, BurundiCarbonatite
DS201511-1830
2015
Decree, S.Decree, S., Boulvais, P., Tack, L., Andre, L., Baele, J-M.Fluorapatite in carbonatite-related phosphate deposits: the case of the Matongo carbonatite. ( Burundi)Mineralium Deposita, in press available 14p.Africa, BurundiCarbonatite

Abstract: The Matongo carbonatite intrusive body in the Neoproterozoic Upper Ruvubu alkaline plutonic complex (URAPC) in Burundi is overlain by an economic phosphate ore deposit that is present as breccia lenses. The ore exhibits evidence of supergene enrichment but also preserves textures related to the concentration of fluorapatite in the carbonatitic system. Magmatic fluorapatite is abundant in the ore and commonly occurs as millimeter-sized aggregates. It is enriched in light rare earth elements (LREE), which is especially apparent in the final generation of magmatic fluorapatite (up to 1.32 wt% LREE2O3). After an episode of metasomatism (fenitization), which led to the formation of K-feldspar and albite, the fluorapatite-rich rocks were partly brecciated. Oxygen and carbon isotope compositions obtained on the calcite forming the breccia matrix (d18O?=?22.1?- and d13C?=?-1.5?‰) are consistent with the involvement of a fluid resulting from the mixing of magmatic-derived fluids with a metamorphic fluid originating from the country rocks. In a subsequent postmagmatic event, the carbonates hosting fluorapatite were dissolved, leading to intense brecciation of the fluorapatite-rich rocks. Secondary carbonate-fluorapatite (less enriched in LREE with 0.07-0.24 wt% LREE2O3 but locally associated with monazite) and coeval siderite constitute the matrix of these breccias. Siderite has d18O values between 25.4 and 27.7?- and very low d13C values (from -12.4 to -9.2?, which are consistent with the contribution of organic-derived low d13C carbon from groundwater. These signatures emphasize supergene alteration. Finally, the remaining voids were filled with a LREE-poor fibrous fluorapatite (0.01 wt% LREE2O3), forming hardened phosphorite, still under supergene conditions. Pyrochlore and vanadiferous magnetite are other minerals accumulated in the eluvial horizons. As a consequence of the supergene processes and fluorapatite accumulation, the phosphate ore, which contains 0.72 to 38.01 wt% P2O5, is also enriched in LREE (LaN/YbN from 47.1 to 83.5; SREE between 165 and 5486 ppm), Nb (up to 656 ppm), and V (up to 1232 ppm). In the case of phosphate exploitation at Matongo, REE could prove to have a subeconomic potential to be exploited as by-products of phosphates.
DS201601-0013
2015
Decree, S.Decree, S., Boulvais, P., Tack, L., Andre, L., Baele, J-M.Fluorapatite in carbonatite related phosphate deposits: the case for the Matongo carbonatite ( Burundi).Mineralogy and Petrology, in press available, 17p.Africa, BurundiCarbonatite

Abstract: The Matongo carbonatite intrusive body in the Neoproterozoic Upper Ruvubu alkaline plutonic complex (URAPC) in Burundi is overlain by an economic phosphate ore deposit that is present as breccia lenses. The ore exhibits evidence of supergene enrichment but also preserves textures related to the concentration of fluorapatite in the carbonatitic system. Magmatic fluorapatite is abundant in the ore and commonly occurs as millimeter-sized aggregates. It is enriched in light rare earth elements (LREE), which is especially apparent in the final generation of magmatic fluorapatite (up to 1.32 wt% LREE2O3). After an episode of metasomatism (fenitization), which led to the formation of K-feldspar and albite, the fluorapatite-rich rocks were partly brecciated. Oxygen and carbon isotope compositions obtained on the calcite forming the breccia matrix (d18O?=?22.1?‰ and d13C?=?-1.5?‰) are consistent with the involvement of a fluid resulting from the mixing of magmatic-derived fluids with a metamorphic fluid originating from the country rocks. In a subsequent postmagmatic event, the carbonates hosting fluorapatite were dissolved, leading to intense brecciation of the fluorapatite-rich rocks. Secondary carbonate-fluorapatite (less enriched in LREE with 0.07-0.24 wt% LREE2O3 but locally associated with monazite) and coeval siderite constitute the matrix of these breccias. Siderite has d18O values between 25.4 and 27.7?‰ and very low d13C values (from -12.4 to -9.2?‰), which are consistent with the contribution of organic-derived low d13C carbon from groundwater. These signatures emphasize supergene alteration. Finally, the remaining voids were filled with a LREE-poor fibrous fluorapatite (0.01 wt% LREE2O3), forming hardened phosphorite, still under supergene conditions. Pyrochlore and vanadiferous magnetite are other minerals accumulated in the eluvial horizons. As a consequence of the supergene processes and fluorapatite accumulation, the phosphate ore, which contains 0.72 to 38.01 wt% P2O5, is also enriched in LREE (LaN/YbN from 47.1 to 83.5; SREE between 165 and 5486 ppm), Nb (up to 656 ppm), and V (up to 1232 ppm). In the case of phosphate exploitation at Matongo, REE could prove to have a subeconomic potential to be exploited as by-products of phosphates.
DS201904-0727
2019
Decree, S.Decree, S., Demaiffe, D., Tack, L., Nimpagaritse, G., De Paepe, P., Bouvais, P., Debaille, V.The Neoproterozoic Upper Ruvubu alkaline plutonic complex ( Burundi) revisited: large scale syntectonic emplacement, magmatic differentiation and late stage circulations of fluids.Precambrian Research, Vol. 325, pp. 150-171.Africa, Burundicarbonatite

Abstract: The Upper Ruvubu Alkaline Plutonic Complex (URAPC) in Burundi consists of three separate intrusions, each with a specific emplacement age and petrological composition. Three main units are recognized: an outer unit with silica-saturated plutonic rocks (from gabbro to granite), an inner unit with silica-undersaturated plutonic rocks (feldspathoidal syenite with subordinate feldspathoidal monzonite and ijolite) and a carbonatitic body in the subsoil, known by drilling. The URAPC is quite large in size (~24?km long and up to 10?km wide). It is considered to have been intruded syntectonically in an overall extensional context, thanks to the kilometric shear zones that accommodated its emplacement. Radiometric ages from literature range from 748 to 705?Ma and point to structurally-controlled magmatic differentiation followed by long-lived circulations of late-stage fluids postdating the emplacement of a part of the undersaturated rocks and the carbonatites. In the north-western part of the outer unit, gabbro likely has been emplaced at a deeper structural level than the granite, which represents a more apical structural level of emplacement. This petrological, geochemical and isotopic (Sr-Nd-Hf) study concentrates on the processes that generated the URAPC: (i) fractional crystallization, evidenced by the chemical evolution trends of the major and trace elements, and by marked P, Ti and Ba anomalies in the trace element patterns; (ii) crustal assimilation/contamination, as shown by the wide range of Nd isotope compositions and the general increase of the Sr isotope ratios with increasing SiO2 contents, and (iii) late-magmatic/hydrothermal alteration inducing an increase of the Sr isotope composition without changing significantly the Nd isotope composition. The isotopic data are consistent with an asthenospheric mantle source, though less depleted than the Depleted Mantle (DM), contaminated by the Subcontinental Lithospheric Mantle (SCLM). The silicate and carbonate magmatic series are cogenetic. The outer unit is clearly more contaminated than the inner unit, whereas the carbonatitic body could have evolved by liquid immiscibility. The URAPC lies within East Africa’s Western Rift Valley, which is marked by 23 alkaline plutonic complexes. Their emplacement has been ascribed to reactivation of Proterozoic lithospheric weakness zones resulting from the breakup of the Neoproterozoic supercontinent Rodinia supercontinent.
DS202005-0729
2020
Decree, S.Decree, S., Cawthorn, G., Deloule, E., Mercadier, J., Frimmel, H., Baele, J-M.Unravelling the processes controlling apatite formation in the Phalaborwa Complex ( South Africa) based on combined cathodluminescence, LA-ICPMS and in-situ O and Sr isotope analyses.Contributions to Mineralogy and Petrology, Vol. 175, 34 31p. PdfAfrica, South Africacarbonatite

Abstract: The Phalaborwa world-class phosphate deposit (South Africa) is hosted by a Paleoproterozoic alkaline complex mainly composed of phoscorite, carbonatite, pyroxenitic rocks, and subordinate fenite. In addition, syenite and trachyte occur in numerous satellite bodies. New petrological and in-situ geochemical data along with O and Sr isotope data obtained on apatite demonstrate that apatite is in the principal host rocks (pyroxenitic rocks, phoscorite and carbonatite) formed primarily by igneous processes from mantle-derived carbonatitic magmas. Early-formed magmatic apatite is particularly enriched in light rare earth elements (LREE), with a decrease in the REE content ascribed to magma differentiation and early apatite fractionation in isolated interstitial melt pockets. Rayleigh fractionation favored a slight increase in d18O (below 1%) at a constant Sr isotopic composition. Intrusion of fresh carbonatitic magma into earlier-formed carbonatite bodies locally induced re-equilibration of early apatite with REE enrichment but at constant O and Sr isotopic compositions. In fenite, syenite and trachyte, apatite displays alteration textures and LREE depletion, reflecting interaction with fluids. A marked decrease in d18O in apatite from syenite and trachyte indicates a contribution from d18O-depleted meteoric fluids. This is consistent with the epizonal emplacement of the satellite bodies. The general increase of the Sr isotope ratios in apatite in these rocks reflects progressive interaction with the country rocks over time. This study made it possible to decipher, with unmatched precision, the succession of geological processes that led to one of the most important phosphate deposits worldwide.
DS202008-1373
2020
Decree, S.Buyse, F., Dewaele, S., Decree, S., Mees, F.Mineralogical and geochemical study of the rare earth element mineralization at Gakara ( Burundi).Ore Geology Reviews, Vol. 124, 103659 10p. PdfAfrica, BurundiREE

Abstract: The rare earth element (REE) mineralization of Gakara (Burundi) has first been discovered in 1936 and has periodically been the subject of geological studies, at times when the exploitation of bastnäsite-(Ce) and monazite-(Ce) was economically interesting. This study focuses on the establishment of a mineral paragenesis for Gakara, with special attention to the REE-bearing phases, to understand the formation history of the deposit. The paragenesis can be subdivided into 3 stages: primary ore deposition, brecciation stage and supergene alteration. Evidence for fenitization processes (i.e. pinkish-red cathodoluminescence of K-feldpar, brecciation stage) and the strong enrichment of light REEs in bastnäsite and monazite substantiate the hypothesis of a structurally controlled hydrothermal mineralization with a strong carbonatitic affinity. This likely confirms the association of the Gakara REE deposit with the Neoproterozoic alignment of alkaline complexes and carbonatites along the present-day Western Rift. It suggests a direct link with a - currently unidentified - carbonatitic body at depth, possibly derived from a predominantly metasomatized lithospheric mantle.
DS202101-0007
2020
Decree, S.Decree, S., Savolainen, M., Mercadier, J., Debaille, V., Hohn, S., Frimmel, H., Baele, J-M.Geochemical and spectroscopic investigation of apatite in the Siilinjarvi carbonatite complex: keys to understanding apatite forming processes and assessing potential for rare earth elements.Applied Geochemistry, Vol. 123, 104778 17p. PdfEurope, Finlanddeposit - Siilinjarvi

Abstract: The Siilinjärvi phosphate deposit (Finland) is hosted by an Archean carbonatite complex. The main body is composed of glimmerite, carbonatite and combinations thereof. It is surrounded by a well-developed fenitization zone. Almost all the rocks pertaining to the glimmerite-carbonatite series are considered for exploitation of phosphate. New petrological and in-situ geochemical as well as spectroscopic data obtained by cathodoluminescence, Raman and laser-induced breakdown spectroscopy make it possible to constrain the genesis and evolution of apatite through time. Apatite in the glimmerite-carbonatite series formed by igneous processes. An increase in rare earth elements (REE) content during apatite deposition can be explained by re-equilibration of early apatite (via sub-solidus diffusion at the magmatic stage) with a fresh carbonatitic magma enriched in these elements. This late carbonatite emplacement has been known as a major contributor to the overall P and REE endowment of the system and is likely connected to fenitization and alkali-rich fluids. These fluids - enriched in REE - would have interacted with apatite in the fenite, resulting in an increase in REE content through coupled dissolution-reprecipitation processes. Finally, a marked decrease in LREE is observed in apatite hosted by fenite. It highlights the alteration of apatite by a REE-poor fluid during a late-magmatic/hydrothermal stage. Regarding the potential for REE exploitation, geochemical data combined with an estimation of the reserves indicate a sub-economic potential of REE to be exploited as by-products of phosphate mining. Spectroscopic analyses further provide helpful data for exploration, by determining the P and REE distribution and the enrichment in carbonatite and within apatite.
DS201112-1154
2011
Dedecek, P.Zavada, P., Dedecek, P., Mach, K., Lexa, O., Potuzak, M.Emplacement dynamics of phonolite magma into maar-diatreme structures - correlation of field, thermal modeling and AMS analogue modeling data.Journal of Volcanology and Geothermal Research, Vol. 201, 1-4, pp. 210-226.EuropeGeodynamics - not specific to diamonds
DS202008-1396
2020
Deditius, A.P.Gonzales-Jiminez, J.M., Tassara, S., Schettino, E., Roque-Rosell, J., Farre-de-Pablo, J., Saunders, J.E., Deditius, A.P., Colas, V., Rovira-Medina, J.J., Guadalupe Davalos, M., Schilling, M., Jiminez-Franco, A., Marchesi, C., Nieto, F., Proenza, J.A., GerMineralogy of the HSE in the subcontinental lithospheric mantle - an interpretive review.Lithos, in press available, 44p. PdfMantleHSE

Abstract: The highly siderophile elements (HSE: Os, Ir, Ru, Rh, Pt, Pd, Re, Au) exist in solid solution in accessory base-metal sulfides (BMS) as well as nano-to-micron scale minerals in rocks of the subcontinental lithospheric mantle (SCLM). The latter include platinum-group minerals (PGM) and gold minerals, which may vary widely in morphology, composition and distribution. The PGM form isolated grains often associated with larger BMS hosted in residual olivine, located at interstices in between peridotite-forming minerals or more commonly in association with metasomatic minerals (pyroxenes, carbonates, phosphates) and silicate glasses in some peridotite xenoliths. The PGM found inside residual olivine are mainly Os-, Ir- and Ru-rich sulfides and alloys. In contrast, those associated with metasomatic minerals or silicate glasses of peridotite xenoliths consist of Pt, Pd, and Rh bonded with semimetals like As, Te, Bi, and Sn. Nanoscale observations on natural samples along with the results of recent experiments indicate that nucleation of PGM is mainly related with the uptake of HSE by nanoparticles, nanominerals or nanomelts at high temperature (> 900?°C) in both silicate and/or sulfide melts, regardless of the residual or metasomatic origin of their host minerals. A similar interpretation can be assumed for gold minerals. Our observations highlight that nanoscale processes play an important role on the ore-forming potential of primitive mantle-derived magmas parental to magmatic-hydrothermal deposits enriched in noble metals. The metal inventory in these magmas could be related with the physical incorporation of HSE-bearing nanoparticles or nanomelts during processes of partial melting of mantle peridotite and melt migration from the mantle to overlying continental crust.
DS1984-0225
1984
Dedkov, G.V.Dedkov, G.V., Shidov, E.K.H.Channelling Radiation of Electrons and Positrons in diamond and Silicon at Intermediate Energies: Theory and Experiment.Radiation Effects Letters, Vol. 85, No. 3, PP. 111-116.GlobalDiamond Research
DS1981-0134
1981
Dedman, R.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
DS201701-0037
2016
Dee, M.W.Walker, R.T., Telfer, M., Kahle, R.L., Dee, M.W., Kahle, J-L., Schwenninger, J-L., Sloan, R.A., Watts, A.B.Rapid mantle driven uplift along the Angolan margin in the Quaternary.Nature Geoscience, Vol. 9, pp. 909-914.Africa, AngolaTectonics

Abstract: Mantle flow can cause the Earth’s surface to uplift and subside, but the rates and durations of these motions are, in general, poorly resolved due to the difficulties in making measurements of relatively small vertical movements (hundreds of metres) over sufficiently large distances (about 1,000?km). Here we examine the effect of mantle upwelling through a study of Quaternary uplift along the coast of Angola. Using both optically stimulated luminescence on sediment grains, and radiocarbon dating of fossil shells, we date a 25?m coastal terrace at about 45 thousand years old, when sea level was about 75?m lower than today, indicating a rapid uplift rate of 1.8-2.6?mm?yr-1 that is an order of magnitude higher than previously obtained rates averaged over longer time periods. Automated extraction and correlation of coastal terrace remnants from digital topography uncovers a symmetrical uplift with diameter of more than 1,000?km. The wavelength and relatively short timescale of the uplift suggest that it is associated with a mantle process, possibly convective upwelling, and that the topography may be modulated by rapid short-lived pulses of mantle-derived uplift. Our study shows that stable continental regions far from the effects of glacial rebound may experience rapid vertical displacements of several millimetres per year.
DS201909-2057
2019
Dee, S.Lee, C-T., Dee, S.Does volcanism cause warming or cooling?Geology , Vol. 47, pp. 687-688.Globalvolcanism

Abstract: On million-year time scales, Earth’s climate fluctuates between warm and cool baselines. For example, the past 40 m.y. has been relatively cool and characterized by a permanent ice sheet on Antarctica, while the interval between 150 and 50 m.y. ago was characterized by warm temperatures and no permanent ice sheets (Royer et al., 2004; Zachos et al., 2008). What controls these fluctuations is debated, but to first order, the average surface temperature of Earth reflects the balance of incoming solar insolation (energy in) versus planetary albedo and greenhouse gas concentrations (energy out). It is generally thought that over the past billion years, the most important control on long-term climate is variations in greenhouse gases in the atmosphere, namely CO2 (Berner, 1991). What controls long-term CO2 are variations in geologic inputs and the efficiency of CO2 sequestration, the former through volcanic and metamorphic degassing and oxidative weathering of organic carbon, and the latter through silicate weathering (and eventual carbonate precipitation) and organic carbon burial. Importantly, the efficiency of silicate weathering and organic carbon burial is widely thought to scale directly and indirectly with atmospheric pCO2; CO2’s impact on global temperature and the hydrologic cycle serves as a negative feedback, enhancing (mitigating) carbon sequestration mechanisms given increased (decreased) inputs of CO2. As the residence time of CO2 in the exogenic system (ocean-atmosphere-biosphere) is on the order of 10-100 k.y., exogenic carbon contents on million-year time scales are at steady state, where inputs equal outputs (Berner and Caldeira, 1997). Changes in exogenic cabon over greater than million-year time scales thus reflect secular changes in the steady-state baseline, driven by changes in inputs and/or the kinetics of carbon sequestration (Fig. 1).
DS201112-0228
2011
Dee DeeCunningham, Dee DeeThe diamond compendium. Illustrations covering origin, properties, crystallography, world distribution,grading, marketing, high techAmazon.com, 888p. 200 colour photos price approx. $300.00TechnologyBook
DS1994-0415
1994
Deeks, W.G.Deeks, W.G.A blueprint for the 21st Century - a Canadian mining counterattackCanadian Institute 1994 Canadian Mining Symposium, Preprint, 17pCanadaEconomics, Mining industry -overview
DS2002-0635
2002
Deemer, S.Hall, J., Louden, K.E., Funck, T., Deemer, S.Geophysical characteristics of the continental crust along the Lithoprobe Eastern Canadian Shield Onshore-Offshore Transect (ECSOOT): a review.Canadian Journal of Earth Science, Vol.39,5, May, pp.569-87.Quebec, Labrador, Baffin IslandGeophysics - ESCOOT, Tectonics
DS200912-0042
2009
DeenBegg, G.C., Griffin, W.L., Natapov, O'Reilly, Grand, O'Neill, Hronsky, Poudjom Djomeni, Swain, Deen, BowdenThe lithospheric architecture of Africa: seismic tomography, mantle petrology, and tectonic evolution.Geosphere, Vol. 5, pp. 23-50.AfricaGeophysics - seismic, tectonics
DS200612-0323
2006
Deen, T.Deen, T.Hot stuff: geotherms, density and seismic velocity.GEMOC Annual Report, 2005, p. 30-31.MantleXenoliths, tomography
DS1998-0333
1998
Deep Probe Working GroupDeep Probe Working GroupProbing the depths of western North America: contrasting Archean and Proterozoic lithosphere ...Geological Society of America (GSA) Today, Vol. 8, No. 7, pp. 1-5.Alberta, Western CanadaGeochronology, Tectonics
DS1998-0334
1998
Deep Probe Working GroupDeep Probe Working GroupProbing the Archean and Proterozoic lithosphere of western North AmericaGsa Today, Vol. 8, No. 7, July, pp. 1-6, 16-17.Wyoming, California, Colorado PlateauGeophysics - seismics, Mantle
DS1986-0176
1986
Deer, W.A.Deer, W.A., Howie, R.A., Zussman, J.Rock forming minerals volume 1B, disilicates and ring silicates. secondeditionLongman Scientific, 630pGlobalMelilite group
DS201805-0974
2018
Deetlefs, B.Sasman, F., Deetlefs, B., van der Westhuyzen, P.Application of diamond size frequency distribution and XRT technology at a large diamond producer. The Journal of the Southern African Institute of Mining and Metallurgy, Vol. 118, Jan. pp. 1-6.Africa, South Africadiamond size frequency

Abstract: Diamond size frequency distribution (SFD) curves, combined with the associated dollar per carat per size class, play an important role in the diamond industry. Value per size class is unique for each deposit and typically varies from less than a dollar per carat to several thousands of dollars per carat for special stones. Recovery of large stone therefore contributes significantly to the bottom line of a large diamond producer. While the design of the process plant should prevent damage and possible breakage of large stones, it should also ensure adequate liberation of the finer diamonds. Innovative solutions are required to protect and recover type I and II diamonds if prominent within the resource. X-ray transmission (XRT) sorting presents the opportunity to develop flow sheet designs that incorporate a balance between exploitation of the resource and process efficiency, as well as practical capital and operating costs. This paper serves to illustrate the role and application of SFD curves in determining optimum cut-off and re-crush sizes within the flow sheet of a large diamond producer. A thorough understanding of the unique technical and economic aspects of a deposit provides the basis from where new and innovative technologies can be proposed, allowing mining companies to maintain and improve profit margins. It highlights the results of various plant trials and newly commissioned XRT sorters for larger size fractions. It also provides recommendations for future applications of XRT machines in the diamond process flow sheet.
DS2001-0241
2001
Deev, E.V.Deev, E.V., Votakh, O.A., Belyaev, S.Y., Zinovev, S.V., Levchuk, M.A.Tectonics of the basement of the mid-Ob plate complex ( West Siberia)Russian Geology and Geophysics, Vol. 42, 6, pp. 920-9.Russia, SiberiaTectonics
DS1998-0738
1998
Defant, M.Kepezhinskas, P., Defant, M., Maury, R., Clague, A.Composition of Island arc mantle and its bearing on the origin of cratoniclithosphere.7th International Kimberlite Conference Abstract, pp. 417-9.GlobalCraton, Subduction
DS2003-1475
2003
Defant, M.Widom, E., Kepezhinskas, P., Defant, M.The nature of metasomatism in the sub-arc mantle wedge: evidence from Re OsChemical Geology, Vol. 196, 1-4, pp. 283-306.RussiaXenoliths
DS200412-2112
2003
Defant, M.Widom, E., Kepezhinskas, P., Defant, M.The nature of metasomatism in the sub-arc mantle wedge: evidence from Re Os isotopes in Kamchatka peridotite xenoliths.Chemical Geology, Vol. 196, 1-4, pp. 283-306.RussiaXenoliths
DS1990-0396
1990
Defant, M.J.Defant, M.J., Drummond, M.S.Derivation of some modern arc magmas by melting of young subductedlithosphereNature, Vol. 347, October 18, pp. 662-665GlobalMantle Subduction
DS1990-0429
1990
Defant, M.J.Drummond, M.S., Defant, M.J.A model for trondhjemite tonalite dacit genesis and crustal growth via slabmelting: archean to modern.Journal of Geophysical Research, Vol. 95, No. B 13, Dec. 10, pp. 21503-21.MantleTectonics, Melting, subduction
DS1991-1923
1991
Defant, M.J.Zeilinga de Boer, J., Defant, M.J., Stewart, R.H., Bellon, H.Evidence for active subduction below western PanamaGeology, Vol. 19, No. 6, June pp. 649-652GlobalGeochronology, Geophysics
DS1992-1014
1992
Defant, M.J.Maury, R.C., Defant, M.J., Joron, J-L.Metasomatism of the sub-arc mantle inferred from trace elements in Philippine xenolithsNature, Vol. 360, Dece, ber 17, pp. 661-663PhilippinesXenoliths, Mantle
DS1995-0939
1995
Defant, M.J.Kepezhinskas, P.K., Defant, M.J., Drummond, M.S.NA metasomatism in the Island Arc mantle by slab melt peridotite interaction -evidence north Kamchatka arcJournal of Petrology, Vol. 36, No. 6, Dec. pp. 1505-1527.RussiaSubduction, Sodium, Metasomatism
DS1996-0727
1996
Defant, M.J.Kepezhinkas, P., Defant, M.J., Drummond, M.S.Progressive enrichment of island arc mantle by melt peridotite interaction inferred - Kamchatka xenoliths.Geochimica et Cosmochimica Acta, Vol. 60, No. 7, April, pp. 1217-1229RussiaXenoliths, Geochemistry - peridotite, Kamchatka Arc, Kamchatka
DS2000-0484
2000
Defant, M.J.Kepezhinskas, P.K., Defant, M.J., Barron, L.M., BarronMeymechites - a new clan of diamond bearing ultramafic rocksIgc 30th. Brasil, Aug. abstract only 1p.Russia, Australia, New South WalesDiamond - genesis, Geochemistry - eclogite
DS2002-0829
2002
Defant, M.J.Kepezhinskas, P., Defant, M.J., Widon, E.Abundance and distribution of PGE and au in the Island arc mantle: implications for sub arc metasomatism.Lithos, Vol.60, pp. 113-28.MantleMetasomatism - platinum group elements, Kamchatka Arc
DS2003-1510
2003
Defant, M.J.Xu, J.F., Shinjo, R., Defant, M.J., Wang, Q., Rapp, R.P.Origin of Mesozoic adakitic intrusive rocks in the Nigzhen area of east China: partialGeology, Vol. 30, 12, Dec.pp. 111-1114.ChinaMelting, mantle, slab
DS2001-0242
2001
Degeling, H.Degeling, H., Eggins, S., Ellis, D.J.Zirconium budgets for metamorphic reactions and the formation of zircon from garnet breakdown.Mineralogical Magazine, Vol. 65, No. 6, pp. 749-58.GlobalMineralogy - garnet
DS201705-0853
2017
de'Gennaro, R.Melluso, L., Guarino, V., Lustrino, M., Morra, V., de'Gennaro, R.The REE- and HFSE-bearing phases in the Itatiaia alkaline complex ( Brazil) and geochemical evolution of feldspar-rich felsic melts.Mineralogical Magazine, Vol. 81, 2, pp. 217-250.South America, BrazilAlkaline rocks

Abstract: The Late Cretaceous Itatiaia complex is made up of nepheline syenite grading to peralkaline varieties, quartz syenite and granite, emplaced in the metamorphic rocks of the Serra do Mar, SE Brazil. The nepheline syenites are characterized by assemblages with alkali feldspar, nepheline, Fe-Ti oxides, clinopyroxene, amphibole, apatite and titanite, while the peralkaline nepheline syenites have F-disilicates (rinkite, wöhlerite, hiortdahlite, låvenite), britholite and pyrophanite as the accessory phases. The silica-oversaturated rocks have alkali feldspar, plagioclase, quartz, amphibole, clinopyroxene and Fe-Ti oxides; the chevkinite-group minerals are the featured accessory phases and are found with allanite, fluorapatite, fluorite, zircon, thorite, yttrialite, zirconolite, pyrochlore and yttrocolumbite. The major- and trace-element composition of the Itatiaia rocks have variations linked to the amount of accessory phases, have smooth, enriched chondrite-normalized rare-earth element (REE) distribution patterns in the least-evolved nepheline syenites and convex patterns in the most-evolved nepheline syenites. The REE distribution patterns of the quartz syenites and granites show a typical pattern caused by fractional crystallization of feldspar and amphibole, in an environment characterized by relatively high oxygen fugacity (>NiNiO buffer) and high concentrations of H2O and F, supporting the crystallization of hydrous phases, fluorite and F-disilicates. The removal of small amounts of titanite in the transition from the least-evolved to the most-evolved nepheline syenites stems from petrogenetic models involving REE, and is shown to be a common feature of the magmatic evolution of many other syenitic/ trachytic/ phonolitic complexes of the Serra do Mar and elsewhere.
DS1960-0881
1967
Degens, E.T.Taylor, H.P.JR. , Frechen, J., Degens, E.T.Oxygen and Carbon Isotope Studies of Carbonatites from the Laacher See District West Germany and the Alno District Sweden.Geochimica Et Cosmochimica Acta, Vol. 31, PP. 407-430.Norway, Germany, ScandinaviaAlnoite
DS202003-0364
2019
DeGhionno, D.Sun, Z., Palke, A. C., Muyal, J., DeGhionno, D., McClaure, S.F.Geographic origin determination of alexandrite.Gems & Gemology, Vol. 55, 4, pp. 660-681.Russia, South America, Brazil, Africa, Tanzania, Zimbabwe, India, Asia, Sri Lankaalexandrite

Abstract: The gem and jewelry trade has come to place increasing importance on the geographic origin of alexandrite, as it can have a significant impact on value. Alexandrites from Russia and Brazil are usually more highly valued than those from other countries. In 2016, GIA began researching geographic origin of alexandrite with the intent of offering origin determination as a laboratory service. Unfortunately, collecting reliable samples with known provenance can be very difficult. Alexandrite is often recovered as a byproduct of mining for other gemstones (e.g., emerald and corundum), so it can be difficult to secure reliable parcels of samples because production is typically erratic and unpredictable. The reference materials studied here were examined thoroughly for their trace element chemistry profiles, characteristic color-change ranges under daylight-equivalent and incandescent illumination, and inclusion scenes. The data obtained so far allow us to accurately determine geographic origin for alexandrites from Russia, Brazil, Sri Lanka, Tanzania, and India. Future work may help to differentiate alexandrites from other localities.
DS2002-0386
2002
Degroote, E.Doblas, M., Lopez-Ruiz, J., Cebria, J-M., Youbi, N., Degroote, E.Mantle insulation beneath the West African craton during Precambrian - Cambrian transition.Geology, Vol. 30,9,Sept. pp. 839-42.West Africa, BrazilGeothermometry, African Craton
DS201708-1573
2017
Degruyter, W.Karakas, O., Degruyter, W., Bachmann, O., Dufek, J.life time and size of shallow magma bodies controlled by crustal-scale magmatism.Nature Geoscience, Vol. 10, 6, p. 446.Mantlemagmatism

Abstract: Magmatic processes on Earth govern the mass, energy and chemical transfer between the mantle, crust and atmosphere. To understand magma storage conditions in the crust that ultimately control volcanic activity and growth of continents, an evaluation of the mass and heat budget of the entire crustal column during magmatic episodes is essential. Here we use a numerical model to constrain the physical conditions under which both lower and upper crustal magma bodies form. We find that over long durations of intrusions (greater than 105 to 106?yr), extensive lower crustal mush zones develop, which modify the thermal budget of the upper crust and reduce the flux of magma required to sustain upper crustal magma reservoirs. Our results reconcile physical models of magma reservoir construction and field-based estimates of intrusion rates in numerous volcanic and plutonic localities. Young igneous provinces (less than a few hundred thousand years old) are unlikely to support large upper crustal reservoirs, whereas longer-lived systems (active for longer than 1 million years) can accumulate magma and build reservoirs capable of producing super-eruptions, even with intrusion rates smaller than 10-3 to 10-2?km3?yr-1. Hence, total duration of magmatism should be combined with the magma intrusion rates to assess the capability of volcanic systems to form the largest explosive eruptions on Earth.
DS201910-2266
2019
Degruyter, W.Huber, C., Townsend, M., Degruyter, W., Bachmann, O.Optimal depth of subvolcanic magma chamber growth controlled by volatiles and crust rheology.Nature Geoscience, Vol. 12, pp. 762-768.Mantlemagmatism

Abstract: Storage pressures of magma chambers influence the style, frequency and magnitude of volcanic eruptions. Neutral buoyancy or rheological transitions are commonly assumed to control where magmas accumulate and form such chambers. However, the density of volatile-rich silicic magmas is typically lower than that of the surrounding crust, and the rheology of the crust alone does not define the depth of the brittle-ductile transition around a magma chamber. Yet, typical storage pressures inferred from geophysical inversions or petrological methods seem to cluster around 2?±?0.5?kbar in all tectonic settings and crustal compositions. Here, we use thermomechanical modelling to show that storage pressure is controlled by volatile exsolution and crustal rheology. At pressures ?1.5?kbar, and for geologically realistic water contents, chamber volumes and recharge rates, the presence of an exsolved magmatic volatile phase hinders chamber growth because eruptive volumes are typically larger than recharges feeding the system during periods of dormancy. At pressures >rsim2.5?kbar, the viscosity of the crust in long-lived magmatic provinces is sufficiently low to inhibit most eruptions. Sustainable eruptible magma reservoirs are able to develop only within a relatively narrow range of pressures around 2?±?0.5?kbar, where the amount of exsolved volatiles fosters growth while the high viscosity of the crust promotes the necessary overpressurization for eruption.
DS1994-0416
1994
Degtjareva, A.I.Degtjareva, A.I., et al.Morphogenetic pecularities of placer diamonds from Anabar river alluvial deposits and genesis.(Russian)Russian Mineralogical Society Proceedings, No. 1, pp. 71-80.Russia, AnabarAlluvials, Diamond morphology
DS201212-0158
2012
Degtyarev, K.E.Degtyarev, K.E., Tretyakov, Kotov, Salnikova, Shatagi, Yakovleva, Anismova, PlotkinaThe Chelkar peridotite-gabbronorite pluton ( Kokchetav massif, northern Kazakhstan): formation type and geochronology.Doklady Earth Sciences, Vol. 446, 2, pp. 1162-1166.Russia, KazakhstanGeochronlogy
DS2003-1455
2003
Deguchi, A.Watanabe, A., Deguchi, A., Kitabatake, M., Kono, S.Field emission from diamond particles studied by scanning field emmision microscopyUltramicroscopy, Vol. 95, pp. 145-51.GlobalTechniques
DS200912-0793
2009
Deguen, R.Venet, L., Duffar, T., Deguen, R.Grain structure of the Earth's inner core.Comptes Rendus Geoscience, In press available, 4p.MantleGeophysics - seismics
DS201112-0261
2011
Deguen, R.Deguen, R., Cardin, P.Thermochemical convection in Earth's inner core.Geophysical Journal International, In press availableMantleGeothermometry
DS201212-0008
2012
Deguen, R.Alboussiere, T., Deguen, R.Asymmetric dynamics of the inner core and impact on the outer core.Journal of Geodynamics, Vol. 61, pp. 172-182.MantleTectonics
DS201212-0159
2012
Deguen, R.Deguen, R.Structure and dynamics of Earth's inner core.Earth and Planetary Science Letters, Vol. 333-334, pp. 211-225.MantleGeodynamics
DS1992-1356
1992
DeHart, J.M.Sears, D.W.G., Lu Jie, Benoit, P.H., DeHart, J.M., Lofgren, G.E.A compositional classification scheme for meteoritic chondrulesNature, Vol. 357, No. 6376, May 21, pp. 207-210GlobalMeteorites, Classification
DS201504-0214
2010
Dehler, M.Reidel, F., Dehler, M.Recovery of unliberated diamonds by x-ray transmission sorting. Earlier paper with size range +8mmThe South African Institute of Mining and Metallurgy, pp. 193-201.TechnologyDiamond recovery
DS201609-1739
2010
Dehler, M.Reidel, F., Dehler, M.Recovery of unliberated diamonds by x-ray transmission sorting.The 4th Colloquium on Diamonds - source to use held Gabarone March 1-3, 2010, 8p.TechnologySorting - X-ray DE-XRT

Abstract: In May 2009 a test work programme was carried out at the sorting laboratory of CommodasUltrasort in Germany which was aimed at establishing the efficiency of Xray transmission sorting for the recovery of unliberated diamonds in a size range of +8mm. A PRO Tertiary XRT belt sorter with a working width of 600mm and a belt speed of - 3mJs was used for the test work. Dual energy X-ray transmission sorting is a type of sensor-based sorting which uses an X-ray scanning system, The attenuation of the transmitting X-rays is measured at two different energy levels, Thereby it is possible to eliminate the effect of the particle thickness on the measurement result. The effective measurement results in a classification by elemental order based on the periodic table. Diamonds are mostly composed of Carbon, which has an atomic number of 6. Compared to Silicon with an atomic number of 14, Diamonds show up much lighter on an XRT image than Silica-based gravels (typical DMS sinks material usually has more dense minerals such as Fe, and Mn which shows an even, darker X-ray image than Si). Tests were run with ele.ven Boarl Diamonds in a size range of -15+8mm mixed into 13kg alluvial DMS sinks gravel in a size range of -25+8mm. All liberated Boart Diamonds were recovered at feed rates of 15t/h at average yields of 7.6g per ejected Diamond. In a second test series the Boarl Diamonds were covered in 20% Gypsum by weight and run again at 15t/h. All unliberated Diamonds were recovered at an average yield of 12.2g per ejected Diamond. The paper outlines the test work results in detail.
DS1995-2063
1995
Dehler, S.A.Williamson, M.C., Courtney, R.C., Keen, C.E., Dehler, S.A.The volume and rare earth concentrations of magmas generated during finite stretching of the lithosphereJournal of Petrology, Vol. 36. No. 5, pp. 1433-1453MantleMagma, Melt, basalt, Rare earths
DS1997-0575
1997
Dehler, S.A.Keen, C.E., Dehler, S.A.Extensional styles and gravity anomalies at rifted continental margins:some North Atlantic examples.Tectonics, Vol. 16, No. 5, Oct. pp. 744-54.Quebec, Labrador, Ungava, GreenlandTectonics, Geophysics - gravity
DS201809-2113
2018
Dehler, S.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.
DS1997-0501
1997
DehlsHenderson, J.R., henderson, M.N., Kerswill, J.A., DehlsGeology of High Lake greenstone belt, District of MackenzieGeological Society of Canada (GSC) Open File, OF. 3401, approx. $ 20.00Northwest TerritoriesBook - ad, Greenstone belt
DS2002-0493
2002
Dehls, J.Gabirelsen, R.H., Braathen, A., Dehls, J., Roberts, D.Tectonic lineaments of NorwayNorsk Geologisk Tidsskrift, Vol. 82, No. 3, pp. 153-174.NorwayTectonics
DS1993-0137
1993
Dehls, J.F.Borradaile, G.J., erner, T., Dehls, J.F., Spark, R.N.Archean regional transpression and paleomagnetism in northwestern CanadaTectonophysics, Vol. 220, No. 1-4, April 15, pp. 117-126OntarioGeophysics, Paleomagnetism
DS1998-0335
1998
Dehls, J.F.Dehls, J.F., Cruden, A.R., Vigneresse, J.L.Fracture control of late Archean pluton emplacement in the northern SlaveProvince.Journal of Structural Geology, Vol. 20, No. 9/10, Sept. pp. 1145-54.Northwest TerritoriesTectonics, structure, Not specific to diamonds
DS1994-1982
1994
Dehuan, X.Zhang Andi, Dehuan, X., Xiling, X., Lihe, G., Jianzong Z., Wuyi W.The status and future of diamond exploration in ChinaProceedings of Fifth International Kimberlite Conference, Vol. 2, pp. 268-284.ChinaDiamond exploration, Review
DS201702-0210
2017
Deibe, D.Deibe, D., Amor, M., Doallo, R., Miranda, M., Cordero, M.GVLiDAR: an interactive web-based visualization frameowrk to support geospatial measures on lidar data.International Journal of Remote Sensing, Vol. 38, 3, pp. 827-849.TechnologyLIDAR

Abstract: In recent years lidar technology has experienced a noticeable increase in its relevance and usage in a number of scientific fields. Therefore, software capable of handling lidar data becomes a key point in those fields. In this article, we present GPU-based viewer lidar (GVLiDAR), a novel web framework for visualization and geospatial measurement of lidar data point sets. The design of the framework is focused on achieving three key objectives: performance in terms of real-time interaction, functionality, and online availability for the lidar datasets. All lidar files are pre-processed and stored in a lossless data structure, which minimizes transfer requirements and offers an on-demand lidar data web framework.
DS200812-0279
2008
Deijanin, B.Deijanin, B., Simic, D., Zaitsev, A., Chapman, J., Dobrinets, I., Widemann, A., Del Re, N., Middleton, T., Dijanin, E., Se Stefano, A.Characterization of pink diamonds of different origin: natural ( Argyle, non-Argyle), irradiated and annealed, treated with multi-process, coated and synthetic.Diamond and Related Materials, Vol. 17, 7-10, pp. 1169-1178.AustraliaPink diamonds
DS200612-0128
2006
Deily, M.E.Bergenstock, D.J., Deily, M.E., Taylor, L.W.A cartel's response to cheating: an empirical investigation of the De Beers diamond empire.Southern Economic Journal, Vol. 73, 1, pp. 173-189.GlobalHistory
DS2001-1069
2001
DeinesShirey, S.B., Harris, James, Deines, Richardson, et al.Geochemical and geophysical perspectives on diamond formation beneath southern Africa.Slave-Kaapvaal Workshop, Sept. Ottawa, 3p. abstractSouth AfricaGeochemistry - diamond inclusions, Diamond - genesis
DS1960-0821
1967
Deines, P.Deines, P.Stable Carbon and Oxygen Isotopes of Carbonatite, Carbonates and Their Interpretation.Ph.d. Thesis, Pennsylvania State University, 230P.United States, Appalachia, PennsylvaniaIsotope Chemistry, Kimberlite
DS1960-0941
1968
Deines, P.Deines, P.The Carbon and Oxygen Isotope Composition of Carbonates From a Mica Peridotite Dike Near Dixonville.Geochimica Et Cosmochimica Acta, Vol. 32, No. 6, PP. 613-625.United States, Appalachia, PennsylvaniaGeochronology
DS1960-0942
1968
Deines, P.Deines, P., Gold, D.P., Herzog, L.F.Variability of C 13 and O 18 in Carbonates from a Mica Peridotite Dike Near Dixonville.Geological Society of America (GSA) SPECIAL PAPER., No. 101, PP. 51-52.United States, Appalachia, PennsylvaniaGeochronology, Carbon
DS1970-0066
1970
Deines, P.Deines, P.The Carbon and Oxygen Isotopic Composition of Carbonates From the Oka Carbonatite Complex Quebec.Geochimica Et Cosmochimica Acta, Vol. 34, No. 11, PP. 1109-1125.Canada, QuebecGeochronology, Related Rocks
DS1970-0663
1973
Deines, P.Deines, P., Gold, D.P.The isotopic composition of carbonatite and kimberlite carbonates and their bearing on isotopic composition..Geochimica Et Cosmochimica Acta, Vol. 37, pp. 1709-33.Uganda, Kenya, East African RiftGeochronology, Composition Of Deep Seated Carbon
DS1975-1102
1979
Deines, P.Kobelski, B.J., Gold, D.P., Deines, P.Variations in Stable Isotope Compositions for Carbon and Oxygen in Some South African Kimberlites.Earth and Planetary Science Letters, Vol. 40, PP.South Africa, LesothoBenfontein, De Beers, Wesselton, Monastery, National, Premier
DS1980-0106
1980
Deines, P.Deines, P.The Carbon Isotopic Composition of Diamonds: Relationship To Diamond Shape, Color, Occurrence and Vapor Composition.Geochimica Et Cosmochimica Acta, Vol. 44, PP. 943-961.South AfricaPremier, Dan Carl, Isotope, Morphology
DS1980-0107
1980
Deines, P.Deines, P.The Carbon Isotope Composition of Diamonds: Relationship To diamond Shape Color, Occurrence and Vapor Composition.Geochimica Et Cosmochimica Acta., Vol. 44, PP. 943-961.South Africa, Premier, BellsbankDiamond, Genesis, Model, Analyses
DS1982-0173
1982
Deines, P.Deines, P.The Relationship between Inclusion Composition and Carbon Isotopic Composition of Host Diamond.Proceedings of Third International Kimberlite Conference, TERRA COGNITA, ABSTRACT VOLUME., Vol. 2, No. 3, P. 202, (abstract.).South AfricaKimberlite, Premier, Finsch, Eclogite
DS1983-0196
1983
Deines, P.Deines, P., Gurney, J.J., Harris, J.W.Associated Chemical and Carbon Isotopic Composition Variations in Diamonds from the Finsch and Premier Kimberlite, South Africa. #1Reprint., 46P. 9FIG.South AfricaGenesis, Diamonds, Kimberlite, Inclusions, Mineral Chemistry
DS1984-0226
1984
Deines, P.Deines, P.Evidence for a Systematic Depletion in 13 C in Parts of The mantle Underlying the Orapa Botswana Kimberlite.Geological Society of America (GSA), Vol. 16, No. 6, P. 485. (abstract.)BotswanaIsotope
DS1984-0227
1984
Deines, P.Deines, P., Gurney, J.J., Harris, J.W.Associated Chemical and Carbon Isotopic Composition Variations in Diamonds from the Finsch and Premier Kimberlite, South Africa. #2Geochimica Et Cosmochimica Acta, Vol. 48, No. 2, FEBRUARY, PP. 325-342.South AfricaMineral Chemistry, Isotope, Chronology
DS1985-0238
1985
Deines, P.Gold, D.P., Deines, P., Ulmer, G.C., Moats, M.A., Weiss, D.Types and Tectonic Settings of Diamond Bearing LamprophyresGeological Association of Canada (GAC)., Vol. 10, P. A21, (abstract.).GlobalReview
DS1986-0177
1986
Deines, P.Deines, P.Stable isotope variations in carbonatites #1Geological Association of Canada (GAC) Annual Meeting, Vol. 11, p. 62. (abstract.)South Africa, CanadaIsotope, Carbonatite
DS1986-0178
1986
Deines, P.Deines, P., Harris, J.W., Gurney, J.J.On the existence of C-13 depleted carbon in the mantle, evidence From diamond studiesProceedings of the Fourth International Kimberlite Conference, Held Perth, Australia, No. 16, pp. 383-385South AfricaRoberts Victor, Diamond morphology
DS1987-0145
1987
Deines, P.Deines, P., Harris, J.W.C13 and O18 and nitrogen content studies of graphite and diamond Eclogites and Orapa ,BotswanaGeological Society of America, Vol. 19, No. 7 annual meeting abstracts, p.639. abstracBotswanaOrapa, Isotope
DS1987-0146
1987
Deines, P.Deines, P., Harris, J.W., Gurney, J.J.Carbon isotope composition, nitrogen content and inclusion composition Of diamonds from the Roberts Victor kimberlite, South Africa- evidence for C 13depletion in tGeochem. Cosmochem.Acta, Vol. 51, No. 5, May pp. 1227-1243South AfricaRoberts Victor, Isotope
DS1988-0165
1988
Deines, P.Deines, P.Causes of correlated variations in the nitrogen content and carbon and nitrogen isotopic composition of diamondsV.m. Goldschmidt Conference, Program And Abstract Volume, Held May, p. 38. AbstractGlobalBlank
DS1988-0166
1988
Deines, P.Deines, P.On the 13 C content of mantle carbonTerra Cognita, 9th. Alfred Wegener Conference, Vol. 8, No. 3, Summer, p. 211. abstractSouthern AfricaMantle, Carbon
DS1989-0346
1989
Deines, P.Deines, P.Oxygen isotope fractionation between coexisting garnets and clinopyroxenes in mantle eclogitesEos, Vol. 70, No. 43, October 24, p. 1411. AbstractBotswanaOrapa, Eclogites
DS1989-0347
1989
Deines, P.Deines, P.Stable isotope variations in carbonatites #2Carbonatites -Genesis and Evolution, Ed. K. Bell Unwin Hyman Publ, pp. 301-359QuebecGeochronology, Oka, Oxygen, Carbon, Sulphur
DS1989-0348
1989
Deines, P.Deines, P.Regularities in the Carbon and nitrogen content of the mantle revealed through studies of diamonds And the chemistry of their inclusionsDiamond Workshop, International Geological Congress, July 15-16th., pp. 18-20. AbstractSouthern Africa, RussiaDiamond morphology, Diamond inclusions -C and
DS1989-0349
1989
Deines, P.Deines, P., Harris, J.W., Spear, P.M., Gurney, J.J.Nitrogen and C-13 content of Finsch and Premier diamonds and theirimplicationsGeochimica et Cosmochimica Acta, Vol. 53, No. 6, June pp. 1367-1378South AfricaDiamond morphology, Diamond inclusions
DS1990-0397
1990
Deines, P.Deines, P.Carbon isotope variabilities in South African mantle and its relationship to depth and peridotitic and eclogitic mineral inclusion chemistryEos, Vol. 71, No. 17, April 24, p. 644 Abstract onlySouth AfricaEclogite, Geochronology -carbon
DS1991-0362
1991
Deines, P.Deines, P.Model simulations of carbon isotope variability in the mantleProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 74-75Southern Africa, RussiaGeochronology -carbon isotope
DS1991-0363
1991
Deines, P.Deines, P., Harris, J.W., Gurney, J.J.The carbon isotopic composition and nitrogen content of lithospheric and asthenospheric diamonds from the Jagersfontein kimberlite, South AfricaGeochimica et Cosmochimica Acta, Vol. 55, pp. 2615-2625South AfricaGeochronology, CI, Nitrogen, Jagersfontein
DS1991-0364
1991
Deines, P.Deines, P., Harris, J.W., Robinson, D.N., Gurney, J.J., Shee, S.R.Carbon and isotope oxygen variations in diamond and graphite eclogites fromOrapa, Botswana and the nitrogen content of their diamondsGeochimica et Cosmochimica Acta, Vol. 55, No. 2, February pp. 515-524BotswanaEclogites, Geochronology, isotopes
DS1992-0353
1992
Deines, P.Deines, P.Carbon isotope studies of diamonds and their implications for the geodynamic cycle of carbon: dat a from the Orapa kimberlite, BotswanaV.m. Goldschmidt Conference Program And Abstracts, Held May 8-10th. Reston, p. A 27. abstractBotswanaGeochronology, Orapa
DS1993-0337
1993
Deines, P.Deines, P., Harris, J.W., Gurney, J.J.Depth related carbon isotope and nitrogen concentration variability in The mantle below the Orapa kimberlite, Botswana, AfricaGeochemica et Cosmochimica Acta, Vol. 57, No. 12, June pp. 2781-2796BotswanaMantle, Deposit -Orapa
DS1994-0417
1994
Deines, P.Deines, P., Harris, J.W.On the importance of fluids for diamond growthMineralogical Magazine, Vol. 58A, pp. 219-220. AbstractSouth AfricaGeochemistry, Sulphide inclusions
DS1995-0409
1995
Deines, P.Deines, P., Haggerty, S.Small scale oxygen isotope variation in ultradeep (>300 KM) and transition zone xenoliths.Proceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 126-8.South AfricaGeochronology, Deposit -Jagersfontein
DS1995-0410
1995
Deines, P.Deines, P., Harris, J.W.Sulfide inclusion chemistry and carbon isotopes of African diamondsGeochimica et Cosmochimica Acta, Vol. 59, No. 15, Aug, pp. 3173-3188.South AfricaGeochemistry, Diamond inclusions -sulphides
DS1995-1965
1995
Deines, P.Van Heerden, L.A., Gurney, J.J., Deines, P.The carbon isotopic composition of harzburgite, lherzolite, websterite, eclogite paragenetic diamondsSouth. African Journal of Geology, Vol. 98, No. 2, June pp. 119-125.South Africa, BotswanaGeochronology -diamonds, Models -genetic
DS1997-0264
1997
Deines, P.Deines, P., Harris, J.W., Gurney, J.J.Carbon isotope ratios, nitrogen content and aggregation state, and inclusion chemistry of diamonds from JwanengGeochimica et Cosmochimica Acta, Vol. 61, No. 18, Sept. pp. 3993-4006.BotswanaMineralogy - diamond inclusions, Deposit - Jwaneng
DS1998-0336
1998
Deines, P.Deines, P.Intra and inter mineral oxygen isoptope variations in kimberlitic zircons7th International Kimberlite Conference Abstract, pp. 187-9.BotswanaKimberlite - zircons, Deposit - Orapa
DS2001-0243
2001
Deines, P.Deines, P., Viljoen, F., Harris, J.W.Implications of the carbon isotope and mineral inclusion record for the formation of diamonds VenetiaGeochimica Et Cosmochimica Acta, Vol. 65, No. 5. Mar. 1, pp. 813-38.South AfricaMantle - underlying mobile belt, Deposit - Venetia
DS2002-0369
2002
Deines, P.Deines, P.The carbon isotope geochemistry of mantle xenolithsEarth Science Reviews, Vol. 58, 3-4, pp. 247-78.MantleGeochronology, Xenoliths - geochemistry - review
DS2002-0370
2002
Deines, P.Deines, P., Harris, J.W.Geochemical characteristics of Southern African diamondsEos, American Geophysical Union, Spring Abstract Volume, Vol.83,19, 1p.South Africa, BotswanaGeochemistry - diamond
DS2002-1536
2002
deines, P.Stachel, T., Haris, J.W., Aulbach, S., deines, P.Kankan diamonds III: delta 13 C and nitrogen characteristics of deep diamondsContributions to Mineralogy and Petrology, Vol. 142, No. 4, pp. 465-75.GuineaGeochronology, Deposit - Kankan
DS200412-0435
2004
Deines, P.Deines, P., Harris, J.W.New insights into the occurrence of 13 C depleted carbon in the mantle from two closely associated kimberlites: Letlhakane and OLithos, Vol. 77, 1-4, Sept. pp. 125-142.Africa, BotswanaDiamond inclusions, carbon isotope, websterite
DS200412-1806
2003
Deines, P.Shirey, S.B., Harris, J.W., Richardson, S.H.,Fouch, M., James, D.E., Cartigny, P.,Deines, P., Vijoen, F.Regional patterns in the paragenesis and age of inclusions in diamond, diamond composition and the lithospheric seismic structurLithos, Vol. 71, 2-4, pp. 243-258.Africa, South AfricaDiamond inclusions
DS201012-0146
2009
Deines, P.Deines, P., Stachel, T., Harris, J.W.Systematic regional variations in diamond carbon isotopic composition and inclusion chemistry beneath the Orapa kimberlite cluster, in Botswana.Lithos, Vol. 112 S pp. 776-784,Africa, BotswanaDeposit - Orapa
DS1985-0144
1985
Deines, R.Deines, R.Identification of 13 C Depleted Mantle Carbon in Diamonds from the roberts Victor Kimberlite, South Africa.Geological Society of America (GSA), Vol. 17, No. 7, P. 561. (abstract.).South AfricaEclogite, Geochronology, Inclusions, Carbon
DS201212-0271
2012
Deino, A.Guo, X., Encarnacion, J., Deino, A., Xu, X., Li, Z., Tian, X.Collision and rotation of the South Chin a block and their role in the formation and exhumation of ultrahigh pressure rocks in the Dabie Shan orogen.Terra Nova, in press availableChinaUHP
DS201212-0272
2012
Deino, A.Guo, X., Encarnacion, J., Xu, X., Deino, A., Li, Z.,Tian, X.Collision and rotation of the South Chin a block and their role in the formation and exhumation of ultrahigh pressure rocks in the Dabie Shan orogen.Terra Nova, Vol. 24, 5, pp. 339-350.ChinaUHP
DS201212-0795
2012
Deino, A.Xiaoyu, G., Encarnacion, J., Xiao, X., Deino, A., Li, Z., Xiabo, T.Collision and rotation of the South Chin a block and their role in the formation and exhumation of ultrahigh pressure rocks in the Dabie Shan orogen.Terra Nova, Vol. 24, 5, pp. 339-350.ChinaUHP
DS1985-0175
1985
Dejager, D.H.Eriksson, S.C., Fourie, P.J., Dejager, D.H.A Cumulate Origin for the Minerals in Clinopyroxenites of ThephalaborwacomplexTransactions Geological Society of South Africa, Vol. 88, pt. 2, May-August pp. 207-214South AfricaCarbonatite
DS201809-2008
2018
Dejanin, B.Chapman, J., Dejanin, B.An overview of synthetic diamond detection - methods and instruments.The Australian Gemmologist, Vol. 26, 9-10, pp. 209-216.Globalsynthetics
DS201212-0803
2012
DeJonge, M.D.Yaxley, G.M., Berry, A.J., Kamenetsky, V.S., Woodland, A.B., Paterson, D., DeJonge, M.D., Howard, D.Application of Fe K-edge xanes determinations of Fe3+/OFE in garnet to peridotite xenoliths from the Udachnaya kimberlite.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractRussia, YakutiaDeposit - Udachnaya
DS201212-0804
2012
DeJonge, M.D.Yaxley, G.M., Berry, A.J., Kamenetsky, V.S., Woodland, A.B., Paterson, D., DeJonge, M.D., Howard, D.Application of Fe K-edge xanes determinations of Fe3+/OFE in garnet to peridotite xenoliths from the Udachnaya kimberlite.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractRussia, YakutiaDeposit - Udachnaya
DS1970-0067
1970
Dejournett, J.D.Dejournett, J.D.Paleomagnetism of Peridotite Dikes Near Ithaca, New YorkBsc. Thesis, Cornell University, 59P.United States, Appalachia, New YorkGeophysics
DS201906-1287
2019
Dekkers, M.J.Dekkers, M.J.Extraordinary Polar wander during the Late Jurassic?EOS, Apr. 28, 3p.Globalgeophysics - gravity

Abstract: Knowing how much Earth’s rotation axis has moved in the geological past - the so-called "polar wander" - has important implications for understanding geological processes. For example, it exposes significant areas on Earth to rapidly changing climatic conditions. The polar shift is a consequence of the Earth responding to a changed center of gravity, caused by processes such as slab-break-off...(no abstract, good graphics)
DS2002-0371
2002
Deksissa, D.J.Deksissa, D.J., Koeberl, C.Geochemistry and petrography of gold quartz tourmaline veins of the Okote area: implications for gold exploreMineralogy and Petrology, Vol.75,1-2, pp. 101-22.Ethiopia, southernGold, geochemistry, Deposit - Okote
DS201911-2562
2019
Dektor, C.Siegrist, M., Yogodzinski, G., Bizimis, M., Fournelle, J., Churikova, T., Dektor, C., Mobley, R.Fragments of metasomatized forearc: origin and implications of mafic and ultramafic xenoliths from Kharchinsky volcano, Kamchatka.Geochemistry, Geophysics, Geosystems, Vol. 20, 9, pp. 4426-4456.Russiaxenoliths

Abstract: This paper presents the results of a study of rare rock fragments (xenoliths) that were transported from the Earth's deep interior to the surface during an eruption of Kharchinsky volcano, Kamchatka. The chemical compositions, mineralogy, and textures of the samples were studied with the goal of understanding the processes that affected rocks, which may play a role in the formation of magmas in the Kamchatka subduction zone. The key process that affected the xenoliths involved the addition of fluids and dissolved elements to the samples at temperatures of 500-700 °C. These fluids are derived from seawater that was transported to 30- to 50-km depths by subduction of the Pacific Plate beneath Kamchatka. Subsequent to the addition of fluid, there was a shift in the position of the Kamchatka-Pacific Plate boundary that led to an increase in temperature and the formation of small quantities of melt that crystallized to a distinctive group of secondary minerals that are present in the samples and that postdate (overprint) the initial effects of fluid addition. The final step in the evolution of the samples was infiltration by an Fe- and Mg-rich magma that crystallized principally amphibole-group minerals.
DS202005-0767
2020
Dekura, H.Tscuchiya, T., Tsuchiya, J., Dekura, H., Ritterbex, S.Ab initio study on the lower mantle minerals.Annual Review of Earth and Planetary Sciences, Vol. 48, 21p. pdfMantlemineralogy

Abstract: Recent progress in theoretical mineral physics based on the ab initio quantum mechanical computation method has been dramatic in conjunction with the rapid advancement of computer technologies. It is now possible to predict stability, elasticity, and transport properties of complex minerals quantitatively with uncertainties that are comparable to or even smaller than those attached in experimental data. These calculations under in situ high-pressure (P) and high-temperature conditions are of particular interest because they allow us to construct a priori mineralogical models of the deep Earth. In this article, we briefly review recent progress in studying high-P phase relations, elasticity, thermal conductivity, and rheological properties of lower mantle minerals including silicates, oxides, and some hydrous phases. Our analyses indicate that the pyrolitic composition can describe Earth's properties quite well in terms of density and P- and S-wave velocity. Computations also suggest some new hydrous compounds that could persist up to the deepest mantle and that the postperovskite phase boundary is the boundary of not only the mineralogy but also the thermal conductivity. 1) The ab initio method is a strong tool to investigate physical properties of minerals under high pressure and high temperature. 2) Calculated thermoelasticity indicates that the pyrolytic composition is representative to the chemistry of Earth's lower mantle. 3) Simulations predict new dense hydrous phases stable in the whole lower mantle pressure and temperature condition. 4) Calculated lattice thermal conductivity suggests a heat flow across the core mantle boundary no greater than 10 TW.
DS202007-1183
2020
Dekura, H.Tscuchiya, T., Tsuchiya, J., Dekura, H., Ritterbex, S.Ab initio study on the lower mantle minerals.Annual Review of Earth and Planetary Sciences, Vol. 48, 1, pp. 99-119.Mantlemineralogy

Abstract: Recent progress in theoretical mineral physics based on the ab initio quantummechanical computation method has been dramatic in conjunction with the rapid advancement of computer technologies. It is now possible to predict stability, elasticity, and transport properties of complex minerals quantitatively with uncertainties that are comparable to or even smaller than those attached in experimental data. These calculations under in situ high-pressure (P) and high-temperature conditions are of particular interest because they allow us to construct a priori mineralogical models of the deep Earth. In this article, we briefly review recent progress in studying high-P phase relations, elasticity, thermal conductivity, and rheological properties of lower mantle minerals including silicates, oxides, and some hydrous phases. Our analyses indicate that the pyrolitic composition can describe Earth’s properties quite well in terms of density and P- and S-wave velocity. Computations also suggest some new hydrous compounds that could persist up to the deepestmantle and that the postperovskite phase boundary is the boundary of not only the mineralogy but also the thermal conductivity.
DS202010-1869
2020
del Camp, A.Pujol-Sola, N., Garcia-Casco, A., Proenza, J.A., Gonzalez-Jiminez, J.M., del Camp, A., Colas, V., Canals, A., Sanchez-Navas, A., Roque-Rosell, J.Diamond forms during low pressure serpentinisation of oceanic lithosphere.Geochemical Perspectives Letters, 7p. PdfCentral America, Cubadiamond genesis

Abstract: Diamond is commonly regarded as an indicator of ultra-high pressure conditions in Earth System Science. This canonical view is challenged by recent data and interpretations that suggest metastable growth of diamond in low pressure environments. One such environment is serpentinisation of oceanic lithosphere, which produces highly reduced CH4-bearing fluids after olivine alteration by reaction with infiltrating fluids. Here we report the first ever observed in situ diamond within olivine-hosted, CH4-rich fluid inclusions from low pressure oceanic gabbro and chromitite samples from the Moa-Baracoa ophiolitic massif, eastern Cuba. Diamond is encapsulated in voids below the polished mineral surface forming a typical serpentinisation array, with methane, serpentine and magnetite, providing definitive evidence for its metastable growth upon low temperature and low pressure alteration of oceanic lithosphere and super-reduction of infiltrated fluids. Thermodynamic modelling of the observed solid and fluid assemblage at a reference P-T point appropriate for serpentinisation (350 °C and 100 MPa) is consistent with extreme reduction of the fluid to logfO2 (MPa) = -45.3 (?logfO2[Iron-Magnetite] = -6.5). These findings imply that the formation of metastable diamond at low pressure in serpentinised olivine is a widespread process in modern and ancient oceanic lithosphere, questioning a generalised ultra-high pressure origin for ophiolitic diamond.
DS1993-1241
1993
Del Moro, A.Pinarelli, L., Boriani, Del Moro, A.The lead isotope systematics during crustal contamination of subcrustalmagmas: the Hercynian magmatism in the Serie dei Laghi Southern Alps, ItalyLithos, Vol. 31, pp. 51-61ItalyDikes, Magmas
DS2003-0446
2003
Del Moro, A.Gasperini, D., Blichert Toft, J., Bosch, D., Del Moro, A., Macera, P., Albaraede, F.Upwelling of deep mantle material through a plate window: evidence from theJournal of Geophysical Research, Vol. 107, 12, Dec. 6, pp. DO1 10.1029/2001JB000418MantleGeophysics - seismics, Tectonics
DS200412-0614
2003
Del Moro, A.Gasperini, D., Blichert Toft, J., Bosch, D., Del Moro, A., Macera, P., Albaraede, F.Upwelling of deep mantle material through a plate window: evidence from the geochemistry of Italian basaltic volcanics.Journal of Geophysical Research, Vol. 107, 12, Dec. 6, pp. DO1 10.1029/2001 JB000418MantleGeophysics - seismics Tectonics
DS1984-0228
1984
Del negro, A.Del negro, A., Carbonin, S., Domeneghetti, C., Molin, G.M.Crystal Chemistry and Evolution of the Clinopyroxene in a SuContributions to Mineralogy and Petrology, Vol. 86, No. 3, PP. 221-229.AustraliaRelated Rocks
DS200612-0324
2006
Del Re, N.Del Re, N.Imaging spectroscopy: a developing frontier for gem analysis.GIA Gemological Research Conference abstract volume, Held August 26-27, p. 23-24. 1/2p.TechnologyUV-Vis-IR and Raman spectroscopy
DS200812-0279
2008
Del Re, N.Deijanin, B., Simic, D., Zaitsev, A., Chapman, J., Dobrinets, I., Widemann, A., Del Re, N., Middleton, T., Dijanin, E., Se Stefano, A.Characterization of pink diamonds of different origin: natural ( Argyle, non-Argyle), irradiated and annealed, treated with multi-process, coated and synthetic.Diamond and Related Materials, Vol. 17, 7-10, pp. 1169-1178.AustraliaPink diamonds
DS1988-0055
1988
Del Sole, T.M.Bernholc, J., Antonelli, A., Del Sole, T.M., Bar-Yam, Y.Mechanism of self-diffusion in diamondPhysical Review Letters, Vol. 61, No. 23, pp. 2689-2692GlobalDiamond morphology, Diamond crystallography -
DS1988-0056
1988
Del Sole, T.M.Bernholc, J., Antonelli, A., Del Sole, T.M., Bar-Yam, Y.Mechanism of self diffusion in diamondPhys. Rev. L., Vol. 61, No. 23, December 5, pp. 2689-2692GlobalDiamond morphology
DS1989-0350
1989
Delagrandville, O.Delagrandville, O.In quest of the Slutsky diamondAm. Econ. Rev, Vol. 79, No. 3, June pp. 468-481GlobalDiamond, Slutsky
DS2001-0458
2001
DelaneyHarvey, S.E., Zonnefeld, Kjarsgaard,Delaney, KelleyTargeted geoscience initiative (TGI) project - Diamondiferous kimberlites of central Sask. overviewSaskatchewan Open House abstracts, Nov. p. 24.SaskatchewanHistory - brief
DS2000-0382
2000
Delaney, G.Hamilton, M.A., Roddick, J.C., Delaney, G.New uranium-lead (U-Pb) geochronological constraints on the age of basement and cover in the eastern Wollaston Domain...Geological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) 2000 Conference, 4p. abstract.SaskatchewanGeochronology, Craton - Rae and Hearne
DS2001-0283
2001
Delaney, G.D.Durocher, K.E., Kyser, K., Delaney, G.D.Thermotectonic studies in the Paleoproterozoic Glennie Domain, Trans Hudson orogen.Precambrian Research, Vol. 109, No. 3-4. July, pp. 175-202.Manitoba, AlbertaTrans Hudson Orogeny, Tectonics, geothermometry
DS2002-0673
2002
Delaney, G.D.Harvey, S.E., Zonneveld, J.P., Delaney, G.D., Kelley, L.Targeted geoscience initiative (TGI) project - Diamondiferous kimberlites of central Sask. - overview.Saskatchewan Geological Survey, Summary Inv.,Vol.2,pp.144-6.SaskatchewanData storage, high resolution 3D, seismic, Stratigraphy
DS2002-0817
2002
Delaney, J.R.Kelley, D.S., Baross, J.A., Delaney, J.R.Volcanoes, fluids and life at mid-ocean ridge spreading centersAnnual Review of Earth and Planetary Sciences, Vol.30,pp. 385-491.MantleVolcanism
DS2002-0818
2002
Delaney, J.R.Kelley, D.S., Baross, J.A., Delaney, J.R.Volcanoes, fluids and life at mid-ocean ridge spreading centersAnnual Review of Earth Planetary Sciences, Vol.30,pp. 385-491.MantleVolcanism
DS1975-0992
1979
Delaney, J.S.Delaney, J.S., Smith, J.V., Dwson, J.B., Nixon, P.H.Manganese Thermometer for Mantle PeridotitesContributions to Mineralogy and Petrology, Vol. 71, pp. 157-69.South AfricaGeothermometry
DS1975-0993
1979
Delaney, J.S.Delaney, J.S., Smith, J.V., Nixon, P.H.Model for upper mantle below m\Malaita, Solomon Islands, deduced from chemistry of lherzolite and megacryst minerals.Contributions to Mineralogy and Petrology, Vol. 70, pp. 209-18.GlobalLherzolite Megacrysts
DS1980-0108
1980
Delaney, J.S.Delaney, J.S., Smith, J.V., Carswell, D.A., Dawson, J.B.Chemistry of Micas from Kimberlites and Xenoliths- Pt. Ii. Primary and Secondary Textured Micas from Peridotite Xenoliths.Geochimica Et Cosmochimica Acta, Vol. 44, PP. 857-872.South AfricaLherzolite, Harzburgite, Mineral Chemistry
DS1980-0109
1980
Delaney, P.T.Delaney, P.T.Magma Flow, Heat Transport and Brecciation of Host Rocks During Dike Emplacement.Ph.d. Thesis, Stanford University, United States, New Mexico, Colorado PlateauDiatreme Formation, Emplacement
DS1981-0135
1981
Delaney, P.T.Delaney, P.T., Pollard, D.D.Deformation of Host Rocks and Flow of Magma During Growth Of Minette Dikes and Breccia- Bearing Intrusions Near Ship Rock, New Mexico.United States Geological Survey (USGS) PROF. PAPER., No. 1202, 61P.United States, New Mexico, Colorado PlateauKimberlite, Diatreme, Colorado Plateau, Rocky Mountains
DS2000-0099
2000
Delaney, P.T.Borgia, A., Delaney, P.T., Denlinger, R.P.Spreading volcanoesAnnual Review Earth Plan. Sci., Vol. 28, pp.539-70.Mantlevolcanism - not specific to diamonds
DS1986-0504
1986
Delano, J.W.Loureiro, D., Delano, J.W.Oxidation states of magnesium ilmenites from South Africa, Algeria and MalaitaEos, Vol. 67, No. 16, April 22, p. 394. (abstract.)South Africa, Algeria, Solomon IslandsBlank
DS1950-0316
1957
Delany, F.Berthoumieux, G., Delany, F.Mission Diamant dans L'ouest OubanguiAef Dir. Mines Et Geol., SECT. B. No. 8, PP. 77-86.GlobalDiamond, Geology
DS1975-0724
1978
Delany, J.S.Dawson, J.B., Smith, J.V., Delany, J.S.Multiple Spinel Garnet Peridotite Transitions in Upper Mantle: Evidence from a Harzburgite Xenolith.Nature., Vol. 273, No. 5665, PP. 741-743.South AfricaPetrography
DS200512-0230
2005
DeLaughter, J.E.DeLaughter, J.E., Stein, C.A., Stein, S.Hotspots: a view from the swells.Plates, Plumes, and Paradigms, pp. 257-278. ( total book 861p. $ 144.00)MantleHotspots
DS201705-0823
2017
Delaunay, A.Delaunay, A., Fritsch, E.A zoned type 1aB/IIa diamond of probable 'Superdeep' origin.Journal of Gemmology, Vol. 35, 5, pp. 397-399.TechnologyDiamond morphology
DS201806-1220
2018
DeLaunay, A.DeLaunay, A., Fritsch, E.Type IIa diamond with extraordinary etch channels.Gems & Gemology, Vol. 54, 1, p. 66.Technologydiamond inclusions
DS201808-1743
2018
Delaunay, A.Fritsch, E., Delaunay, A.What truly characterises a Chameleon diamond? An example of an Atypical 25.85 ct stone. ( Diamondvision)Journal of Gemmology, Vol. 36, 2, pp. 142-151.Technologydiamond - morphology

Abstract: We document an exceptionally large, 25.85 ct diamond that shows a slight colour change but exhibits some atypical properties for chameleon diamonds, including white luminescence to long- and short-wave UV radiation, as well as a network-like pattern seen in most orientations with the DiamondView. In considering whether to call this a chameleon diamond, we undertook a review of available data to compile the properties that are commonly exhibited by these gems. We found that, in addition to their defining photochromic and thermochromic behaviour, nine characteristics all must be present: long-lasting yellow phosphorescence, a zoned DiamondView growth pattern showing yellow-green/blue/inert areas, the presence of dominant A aggregates and also some hydrogen in the infrared spectrum, a continuum of absorption in the visible range related to a very weak type Ib character, a 480 nm absorption band that is possibly related to trace amounts of oxygen, a 425 nm absorption band, a weaker absorption band in the red to near-infrared region consistent with hydrogen-related defects, and traces of nickel detected with photoluminescence spectroscopy.
DS201810-2334
2018
DeLaunay, A.Juncker, C., Herreweghe, A., DeLaunay, A.Les diamants de Golconde.Revue de Gemmologie A.F.G. IN: French, No. 202, pp. 22-26Indiahistory
DS1860-0983
1897
Delaunay, L.Delaunay, L.Les Diamants du CapParis: Baudry, 239P.Africa, South Africa, Cape ProvinceGeology
DS1860-0984
1897
Delaunay, L.Delaunay, L.Sur Les Roches Diamantiferes du Cap et Leurs Variation En Profondeur.Academy of Science (PARIS) C.R., Vol. 125, PP. 335-337. ALSO: Neues Jahrbuch fnr Mineralogie BD. 2, P. 254Africa, South Africa, Cape ProvinceMineralogy, Petrology
DS1900-0182
1903
Delaunay, L.Delaunay, L.Note sur la Theorie des Gites MinerauxAnnual Mines (PARIS), Vol. 10, Vol. 3, PP. 49-116.GlobalGenesis
DS1900-0183
1903
Delaunay, L.Delaunay, L.Les Richesses Minerales de L' AfriqueParis: Beranger., 426P.Africa, South AfricaDiamond Occurrence
DS1900-0546
1907
Delaunay, L.Delaunay, L.Sur la Rencontre du Granite dans le Cheminee Diamantifere De Beers.Academy of Science (PARIS) C.R., Vol. 145, PP. 1188-1189. ALSO: CHEM. abstract., Vol. 2, P.Africa, South AfricaPetrology
DS1910-0342
1913
Delaunay, L.Delaunay, L.Traite de MetallogenieUnknown, 858P.South Africa, GlobalMetallogeny, Genesis, Kimberley
DS201812-2801
2017
Delavault, H.Dhuime, B., Hawkesworth, C.J., Delavault, H., Cawood, P.A.Rates of generation and destruction of the continental crust: implications for continental growth.Philosphical Transactions of the Royal Society, http://dx.doi.org/ 10.1098/rsta .2017.0403 12p. AvailableMantleplate tectonics

Abstract: Less than 25% of the volume of the juvenile continental crust preserved today is older than 3?Ga, there are no known rocks older than approximately 4?Ga, and yet a number of recent models of continental growth suggest that at least 60-80% of the present volume of the continental crust had been generated by 3?Ga. Such models require that large volumes of pre-3?Ga crust were destroyed and replaced by younger crust since the late Archaean. To address this issue, we evaluate the influence on the rock record of changing the rates of generation and destruction of the continental crust at different times in Earth's history. We adopted a box model approach in a numerical model constrained by the estimated volumes of continental crust at 3?Ga and the present day, and by the distribution of crust formation ages in the present-day crust. The data generated by the model suggest that new continental crust was generated continuously, but with a marked decrease in the net growth rate at approximately 3?Ga resulting in a temporary reduction in the volume of continental crust at that time. Destruction rates increased dramatically around 3 billion years ago, which may be linked to the widespread development of subduction zones. The volume of continental crust may have exceeded its present value by the mid/late Proterozoic. In this model, about 2.6-2.3 times of the present volume of continental crust has been generated since Earth's formation, and approximately 1.6-1.3 times of this volume has been destroyed and recycled back into the mantle.
DS201603-0371
2016
Delcamp, A.Delcamp, A., Delvaux, D., Kwelwa, S., Macheyeki, A., Kervyn, M.Sector collapse events at volcanoes in the North Tanzanian divergence zone and their implications for regional tectonics. ( Oldoinyo Lengai)Geological Society of America Bulletin, Vol. 128, 1/2, pp. 169-186.Africa, TanzaniaLineaments

Abstract: The North Tanzanian divergence zone along the East African Rift is characterized by active faults and several large volcanoes such as Meru, Ol Doinyo Lengai, and Kilimanjaro. Based on systematic morphostructural analysis of the Shuttle Radar Topographic Mission digital elevation model and targeted field work, 14 debris avalanche deposits were identified and characterized, some of them being - to our knowledge - previously unknown. Our field survey around Mount Meru allowed previous "lahar" deposits to be reinterpreted as debris avalanche deposits and three major collapse events to be distinguished, with the two older ones being associated with eruptions. We used topographic lineaments and faults across the North Tanzanian divergence zone to derive the main tectonic trends and their spatial variations and highlight their control on volcano collapse orientation. Based on previous analogue models, the tectonic regime is inferred from the orientation of the collapse scars and/or debris avalanche deposits. We infer two types of regime: extensional and transtensional/strike-slip. The strike-slip regime dominates along the rift escarpment, but an extensional regime is inferred to have operated for the recent sector collapses. The proposed interpretation of sector collapse scars and debris avalanche deposits therefore provides constraints on the tectonic regime in the region. It is possible that, in some cases, movement on regional faults triggered sector collapse.
DS201904-0757
2019
Deldicque, C.Malavergegne, V., Bureau, H., Raepsaet, C., Gaillard, C., Poncet, F., Surble, M., Sifre, S., Shcheka, D., Fourdrin, S., Deldicque, C., Khodja, D., HichamExperimental constraints on the fate of H and C during planetary core-mantle differentiation. Implications for the Earth.Icarus - New York, Vol. 321, 1, pp. 473-485.Mantlecarbon

Abstract: Hydrogen (H) and carbon (C) have probably been delivered to the Earth mainly during accretion processes at High Temperature (HT) and High Pressure (HP) and at variable redox conditions. We performed HP (1-15?GPa) and HT (1600-2300°C) experiments, combined with state-of-the-art analytical techniques to better understand the behavior of H and C during planetary differentiation processes. We show that increasing pressure makes H slightly siderophile and slightly decreases the highly siderophile nature of C. This implies that the capacity of a growing core to retain significant amounts of H or C is mainly controlled by the size of the planet: small planetary bodies may retain C in their cores while H may have rather been lost in space; larger bodies may store both H and C in their cores. During the Earth's differentiation, both C and H might be sequestrated in the core. However, the H content of the core would remain one or two orders of magnitude lower than that of C since the (H/C)core ratio might range between 0.04 and 0.27.
DS200812-0280
2008
Delechat, C.Delechat, C., Gaertner, M.Exchange rate assessment in a resource - dependent economy: the case of Botswana.IMF Working Papers, April 1, no. 8083, 200, pp. 1-29. Avail from ingentaAfrica, BotswanaEconomics
DS1996-1502
1996
Dele-Duboi, M.L.Wang, A., Pasteris, J.D., Dele-Duboi, M.L.Magnesite bearing inclusion assemblage in natural diamondEarth and Planetary Science Letters, Vol. 141, No. 1-4, June 1, pp. 293-GlobalDiamond morphology, Magnesite inclusions
DS1994-1880
1994
Dele-Dubois, M.L.Wang, A., Meyer, H.O.A., Dele-Dubois, M.L.Magnesite: an inclusion in natural diamondGeological Society of America (GSA) Abstract Volume, Vol. 26, No. 7, ABSTRACT only p. A417.South AfricaDiamond inclusion -magnesite, Deposit - Finsch
DS2003-1428
2003
Delenitsin, A.A.Vetrin, V.R., Delenitsin, A.A.Proterozoic mantle crust interaction in the Archean basement of the Pechenga paleoriftDoklady Earth Sciences, Vol. 391, 5, pp.689-92.MantleTectonics - rifting not specific to diamonds
DS200412-2058
2003
Delenitsin, A.A.Vetrin, V.R., Delenitsin, A.A.Proterozoic mantle crust interaction in the Archean basement of the Pechenga paleorift.Doklady Earth Sciences, Vol. 391, 5, pp.689-92.MantleTectonics - rifting not specific to diamonds
DS200712-0231
2006
Deleplace, B.Deleplace, B., Cardin, P.Viscomagmatic torque at the core mantle boundary.Geophysical Journal International, Vol. 167, 2, Nov. 1, pp. 557-566.MantleGeodynamics
DS200712-0232
2007
Delescluse, M.Delescluse, M., Chamot-Rooke, N.Instantaneous deformation and kinematics of the India-Australia plate.Journal of Geophysics International, Vol. 168, 2, pp. 818-India, AustraliaTectonics
DS201312-0159
2012
Delfiner, P.Chiles, J-P., Delfiner, P.Geostatistics: modelling spacial uncertainty.Wiley Blackwell, ISBN 978-0-470 699p.TechnologyBook - ad
DS2000-0225
2000
Delgado Granados, H.Delgado Granados, H., Aguirre-Diaz, G.J., Stock, J.M.Cenozoic tectonics and volcanism of MexicoGeological Society of America Special paper, No. 334, 300p.MexicoBook - table of contents
DS201412-0424
2013
Delgaty, J.Januszczak, N., Seller, M.H., Kurzlaukis, S., Murphy, C., Delgaty, J., Tappe, S., Ali, K., Zhu, J., Ellemers, P.A multidisciplinary approach to the Attwapiskat kimberlite field, Canada: accelerating the discovery-to-production pipeline.Proceedings of the 10th. International Kimberlite Conference, Vol. 2, pp. 157-172.Canada, Ontario, AttawapiskatDeposit - Victor area
DS201708-1625
2017
Delgaty, J.Delgaty, J.Ontario's newest kimberlite cluster - the Pagwachuan cluster.11th. International Kimberlite Conference, PosterCanada, Ontariodeposit - Pagawachuan
DS201212-0338
2012
Delgaty, S.Januszcak, M.H., Seller, S., Kurzlaukis, C., Murphy, J., Delgaty, S., Tappe, K., Ali, J.Zhu, Ellemers, P.A multidisciplinary approach to the Attawapiskat kimberlite field, Canada Canada: accelerating the discovery to production pipeline.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractCanada, Ontario, AttawapiskatDeposit - Victor
DS200612-0325
2006
Delgnacio, C.Delgnacio, C., Muoz, M., Sagredo, J., Fernandez, Santan, S., JohanssonIsotope geochemistry and FOZO mantle component of the alkaline carbonatitic association of Fuerteventura, Canary Islands, Spain.Chemical Geology, Vol. 232, 3-4, pp. 99-113.Europe, Spain, Canary IslandsCarbonatite
DS1988-0060
1988
Delhai, J.Bingen, B., Demaiffe, D., Delhai, J.Aluminous granulites of the Archean craton of Kasai(Zaire): petrology and P-T conditionsJournal of Petrology, Vol. 29, No. 4, August pp. 899-920Democratic Republic of CongoPetrology, Craton
DS1984-0179
1984
Delhal, J.Cahen, L., Snelling, N.J., Delhal, J., Vail, J.R.The Geochronology and Evolution of AfricaOxford Clarendon Press, 512P.Africa, South Africa, West Africa, Central Africa, East AfricaKimberley, Tectonics, Structure, Regional Geology
DS200812-0066
2008
Delino, P.Austin-Erickson, A., Buttner, R., Delino, P., Ort, M.H., Zimanowski, B.Phreatomagmatic explosions of rhyolitic magma: experimental and field evidence.Journal of Geophysical Research, Vol. 113, B11201.TechnologyMagmatism
DS1991-0365
1991
Delisle, P.C.Delisle, P.C.Mineral occurrence investigations in Esquega and Corbiere Townships, WawaDistrictOntario Geological Survey Open File, Open File No. 5798, 122pOntarioMineral database, Wawa area
DS201312-0203
2013
Delitsky, M.L.Delitsky, M.L., Baines, K.H.Comment: Jupiter and Saturn could be diamond-rich.UniverseToday.com, 1p.TechnologyLiquid diamond idea
DS200412-0436
2004
Deljanin, B.Deljanin, B.Chameleon diamonds. Those rare stones can change colours when subjected to heat, or removed from light.Canadian Diamonds, Summer, p. 24-25.TechnologyNews item - colour diamonds
DS200512-0388
2005
Deljanin, B.Hainschwang, T., Simic, D., Fritsch, E., Deljanin, B., Woodring, S., DelRe, N.A gemological study of a collection of Chameleon diamonds.Gems & Gemology, Vol. 41, 1, Spring pp. 20-34.Diamond morphology - Chamelon - colour change
DS200712-0233
2006
Deljanin, B.Deljanin, B., Simic, D.Cross referencing identification system (CIS): database and tool for diamond research.Gems & Gemology, 4th International Symposium abstracts, Fall 2006, p.163-64. abstract onlyTechnologyCIS
DS200712-0234
2006
Deljanin, B.Deljanin, B., Simic, D., Epeloym, M., Zaitsev, A.M.Study of fancy color and near colorless HPHT grown synthetic diamonds from advanced optical technology Co. Canada.Gems & Gemology, 4th International Symposium abstracts, Fall 2006, p.154-5. abstract onlyTechnologySynthetic diamonds
DS201511-1831
2015
Deljanin, B.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).
DS201901-0025
2018
Deljanin, B.Deljanin, B., Chapman, J.Steps in screening and ID of laboratory-grown diamonds with synthetic diamond ID kit.Gems & Gemology, Sixth International Gemological Symposium Vol. 54, 3, 1p. Abstract p. 305-6.Globalsynthetics

Abstract: Laboratory-grown diamonds are created using either high-pressure, high-temperature (HPHT) or chemical vapor deposition (CVD). With the influx of manmade diamonds on the market over the past few years, instrument producers and labs have launched screening and detection instruments to help dealers and jewelers spot HPHTor CVD-grown specimens. Most standard instruments are inaccurate testers or just type I and type II screening devices that do not give a definite answer about diamond genesis. Over the last four annual Mediterranean Gemmological and Jewellery Conferences and more than 30 workshops given in 17 countries, we have assembled a portable new Synthetic Diamond Identification Kit. The kit comprises two portable instruments and two booklets: 1) A PL inspector (mini UV lamp with magnifier) to inspect laboratory-grown, treated, and natural diamonds using long- and short-wave fluorescence and phosphorescence 2) A 2017 handbook with images and explanation of longand short-wave reactions of diamonds of all types 3) A mini foldable polariscope with portable light to separate natural diamonds using characteristic birefringence patterns from HPHT and CVD diamonds 4) A 2010 handbook with images and explanations of crosspolarized filter reactions of diamonds of all types The combination of this kit with professional training could identify all HPHT-grown diamonds and most CVD-grown diamonds on the market, loose or mounted. Also available are melee and jewelry inspectors consisting of larger UV lamps with magnifiers designed for identification of small loose or mounted diamonds. Different diamond types and subtypes can exhibit different birefringence under cross-polarized filters. A clear majority of natural diamonds exhibit some degree of internal strain, with type II natural diamonds showing a weak “tatami” pattern. HPHTgrown diamonds are free of such strain, and CVD-grown diamonds show mostly coarse columnar patterns. Most natural diamonds have a strong reaction to long-wave UV; this reaction is usually weaker (mostly blue) at shorter wavelengths. Laboratory-grown diamonds generally exhibit more intense fluorescence with short-wave UV compared to long-wave UV, with a chalky coloring tinged with green or yellow. Most HPHT-grown diamonds also phosphoresce. If a diamond is free of inclusions, fluorescence is a reliable screening test to flag suspicious stones that should be further checked under cross-polarized filters (figure 1). In the case of some rare near-colorless clean CVD-grown diamonds that do not show fluorescence or have a birefringence pattern that is coarse but resembling tatami in type IIa and weak patterns in natural Ia diamonds, additional tests using advanced spectroscopy and strong short-wave UV light to observe growth patterns are needed to confirm diamond genesis.
DS1986-0160
1986
Della Gusta, A.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
DS1975-0252
1976
Della valle, R.S.Brookins, D.G., Della valle, R.S., Bolivar, S.L.Uranium Geochemistry of Some United States KimberlitesEos, Vol. 57, No. 10, P. 762, (abstract.).United States, Gulf Coast, Arkansas, Central States, Rocky Mountains, NebraskaBlank
DS1975-0963
1979
Della valle, R.S.Brookins, D.G., Della valle, R.S., Bolivar, S.L.Significance of Uranium Abundance in United States Kimberlites.International Kimberlite Conference SECOND Proceedings, Vol. 1, PP. 280-288.United States, Gulf Coast, Arkansas, Appalachia, Kentucky, Central StatesUranium
DS1991-0366
1991
Della Ventura, G.Della Ventura, G., Robert, J-L, Beny, J-M.Tetrahedrally coordinated Ti4+ in sythetic Ti-rich potassic richterite:evidence from XRD, FTIR, and Raman studiesAmerican Mineralogist, Vol. 76, pp. 1134-1140GlobalExperimental petrology, Potassic richterite
DS200712-0235
2007
Della Ventura, G.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
Della Ventura, G.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
DS201712-2669
2017
Della Ventura, G.Agrosi, G., Tempestra, G., Della Ventura, G., Guidi, M., Hutchison, M., Nimis, P., Nestola, F.Non-destructive in situ study of plastic deformations in diamonds: x-ray diffraction topography and micro-FTIR mapping of two super deep diamond crystals from Sao Luiz ( Juina, Brazil).Crystals, Vol. 7, #233South America, Brazildeposit - Juina

Abstract: Diamonds from Juina, Brazil, are well-known examples of superdeep diamond crystals formed under sublithospheric conditions and evidence would indicate their origins lie as deep as the Earth's mantle transition zone and the Lower Mantle. Detailed characterization of these minerals and of inclusions trapped within them may thus provide precious minero-petrogenetic information on their growth history in these inaccessible environments. With the aim of studying non-destructively the structural defects in the entire crystalline volume, two diamond samples from this locality, labelled JUc4 and BZ270, respectively, were studied in transmission mode by means of X-ray Diffraction Topography (XRDT) and micro Fourier Transform InfraRed Spectroscopy (µFTIR). The combined use of these methods shows a good fit between the mapping of spatial distribution of extended defects observed on the topographic images and the µFTIR maps corresponding to the concentration of N and H point defects. The results obtained show that both samples are affected by plastic deformation. In particular, BZ270 shows a lower content of nitrogen and higher deformation, and actually consists of different, slightly misoriented grains that contain sub-grains with a rounded-elongated shape. These features are commonly associated with deformation processes by solid-state diffusion creep under high pressure and high temperature.
DS201901-0001
2017
Della Ventura, G.Agrosi, G., Tempesta, G., Della Ventura, G., Cestelli Guidi, M., Hutchison, M., Nimis, P., Nestola, F.Non-destructive in situ study of plastic deformation in diamonds: X-ray diffraction topography and uFTIR mapping of two super deep diamond crystals from Sao Luiz ( Juina, Brazil).Crystals MDPI, Vol. 7, 8, 11p. Doi.org/10. 3390/cryst7080233South America, Brazildeposit - Juina

Abstract: Diamonds from Juina, Brazil, are well-known examples of superdeep diamond crystals formed under sublithospheric conditions and evidence would indicate their origins lie as deep as the Earth’s mantle transition zone and the Lower Mantle. Detailed characterization of these minerals and of inclusions trapped within them may thus provide precious minero-petrogenetic information on their growth history in these inaccessible environments. With the aim of studying non-destructively the structural defects in the entire crystalline volume, two diamond samples from this locality, labelled JUc4 and BZ270, respectively, were studied in transmission mode by means of X-ray Diffraction Topography (XRDT) and micro Fourier Transform InfraRed Spectroscopy (µFTIR). The combined use of these methods shows a good fit between the mapping of spatial distribution of extended defects observed on the topographic images and the µFTIR maps corresponding to the concentration of N and H point defects. The results obtained show that both samples are affected by plastic deformation. In particular, BZ270 shows a lower content of nitrogen and higher deformation, and actually consists of different, slightly misoriented grains that contain sub-grains with a rounded-elongated shape. These features are commonly associated with deformation processes by solid-state diffusion creep under high pressure and high temperature.
DS201905-1020
2019
Della Ventura, G.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.
DS201911-2514
2019
Della Ventura, G.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.
DS201912-2766
2019
Della Ventura, G.Agrosi, G., Tempesta, G., Mele, D., Caggiani, MC., Mangone, A., Della Ventura, G., Cestelli-Guidi, M., Allegretta, I., Hutchison, M.T., Nimis, P., Nestola, F.Multiphase inclusions associate with residual carbonate in a transition zone diamond from Juina, Brazil.Lithos, in press available, 31p. pdfSouth America, Brazildeposit - Juina

Abstract: Super-deep diamonds and their mineral inclusions preserve very precious information about Earth’s deep mantle. In this study, we examined multiphase inclusions entrapped within a diamond from the Rio Vinte e um de Abril, São Luiz area (Juina, Brazil), using a combination of non-destructive methods. Micro-Computed X-ray Tomography (µ-CXRT) was used to investigate the size, shape, distribution and X-Ray absorption of inclusions and mapping by micro X-ray Fluorescence (µ-XRF), µ-Raman Spectroscopy and micro-Fourier Transform Infrared Spectroscopy (µ-FTIR) were used to determine the chemical and mineralogical composition of the inclusions. Four large inclusions enclosed in the N-rich diamond core consist of dominant ferropericlase-magnesiowüstite and locally exsolved magnesioferrite. FTIR maps, obtained integrating the band at 1430 cm-1, show also the presence of carbonates. A fifth large inclusion (ca 100 µm) was remarkable because it showed a very unusual flask shape, resembling a fluid/melt inclusion. Based on µCXRT tomography and µ-Raman mapping, the flask-shaped inclusion is polyphase and consists of magnetite and hematite partly replacing a magnesiowüstite core and small-volume of gas/vacuum. µ-Raman spectra on the same inclusion revealed local features that are ascribed to post-spinel polymorphs, such as maohokite or xieite, which are stable at P = 18 GPa, and to huntite, a carbonate with formula CaMg3(CO3)4. This represents the first finding of maohokite and huntite in diamond. We interpret the composition of the inclusions as evidence of formation of ferropericlase-magnesiowüstite and diamond in a carbonate-rich environment at depths corresponding at least to the Transition Zone, followed by oxidation of ferropericlase-magnesiowüstite by reaction with relatively large-volume entrapped melt during diamond ascent.
DS1995-0411
1995
Dellapasqua, F.N.Dellapasqua, F.N., Kamentsy, V.S., Gasparon, CrawfordAl-spinels in primitive arc volcanicsMineralogy Petrology, Vol. 53, No. 1-3, pp. 1-26.AustraliaMineralogy -spinels
DS201609-1752
2010
Dellas, G.Valbom, D.M.C., Dellas, G.State of the art recovery plant design.The 4th Colloquium on Diamonds - source to use held Gabarone March 1-3, 2010, 10p.TechnologySorting

Abstract: The introduction of new diamond sorting technologies as well as additional manufacturers I vendors, has increased the equipment selection and combinations available for recovery flowsheet design. This paper describes the methodology used and the benefits realized in the design of recovery plants by ensuring a fundamental understanding of the advantages and limitations of the technology embodied in the equipment, a comprehensive knowledge of the ore body characteristics, and the effective matching of this information in combination with operational commercial requirements.
DS201807-1535
2018
Dellas, G.Voigt, A., Morrison, G., Hill, G., Dellas, G., Mangera, R.The application of XRT in the De Beers Group of Companies. Jwaneng, marineSAIMM Diamonds - source to use 2018 Conference 'thriving in changing times'. June 11-13., pp. 173-184.Africa, Botswana, NamibiaXRT sorters
DS201808-1795
2018
Dellas, G.Voight, A., Morrison, G., Hill, G., Dellas, G., Mangera, R.The application of XRT in the De Beers Group of Companies. PresentationSAIMM Diamonds - source to use 2018 Conference 'thriving in changing times'. June 11-13., 25 ppts.GlobalMining - XRT
DS201904-0797
2019
Dellas, G.Voigt, A., Morrison, G., Hikll, G., Dellas, G., Mngera, R.The application of XRT in the De Beers Group of Companies. The Southern African Institute of Mining and Metallurgy, Vol. 119, pp. 149-154.Africa, South Africamineral processing - XRT
DS200512-0209
2005
Dellas, N.Das Gupta, R., Hirschmann, M.M., Dellas, N.The effect of bulk composition on the solidus of carbonated eclogite from partial melting experiments at 3? GPAContributions to Mineralogy and Petrology, Vol. 149, 3, pp. 288-305.Eclogite, mineral chemistry
DS200512-0211
2005
Dellas, N.Dasgupta, R., Hirschmann, M.M., Dellas, N.The effect of bulk composition on the solidus of carbonated eclogite from partial melting experiments at 3 GPa.Contributions to Mineralogy and Petrology, Vol. 149, 3, May pp. 288-305.MantleExperimental petrology, eclogites, peridotites, carbonatites
DS200612-0202
2006
Dellino, P.Buttner, R., Dellino, P., Raue, H., Sonder, I., Zimanowski, B.Stress induced brittle fragmentation of magmatic melts: theory and experiments.Journal of Geophysical Research, Vol. 111, No. B8, B08204MantleMagmatism
DS201212-0168
2012
Dellino, P.Doronzo, D.M., Mart, J., Sulpizio, R., Dellino, P.Aerodynamics of stratovolcanoes during multiphase processes.Journal of Geophysical Research,, Vol. 117, B1, B01207.MantleVolcanoes
DS1970-0215
1970
Dellwig, L.F.Wing, R.S., Dellwig, L.F.Radar Expression of Virginia Dale Precambrian Ring Dike Complex, Wyoming Colorado.Geological Society of America (GSA) Bulletin., Vol.81, PP. 293-298.United States, State Line, Colorado, Wyoming, Rocky MountainsRemote Sensing, Related Rocks
DS200712-0237
2007
DeloiteDeloiteChin a & India. Comparing the world's hottest consumer markets.Deloite, June 8p.China, IndiaEconomics
DS1985-0145
1985
Delong, S.E.Delong, S.E.Systematics of intrinsic oxygen fugacity temperature relationships in multi phase assemblagesAmerican Mineralogist, Vol. 70, No. 11-12, pp. 1164-1168GlobalMineralogy
DS1997-0626
1997
Delor, C.Kouamelan, A.N., mPeucat, J.J., Delor, C.Pre-Leonian relics ( 3.15 Ga) involved in the juvenile Birmian terrains(2.1 Ga) of the Ivory CoastC.r. Acad. Sci, Vol. 324, 11a, pp. 719-727GlobalArchean, transition zone, Geochronology
DS2001-1154
2001
Delor, C.Thieblemont, D., Delor, C., Cocherle, A., Lafon et al.A 3.5 Ga granite-gneiss basement in Guinea: further evidence for early Archean accretion West Africa CratonPrecambrian Research, Vol. 108, No. 3, June 1, pp. 179-194.GuineaCraton - not specific to diamonds
DS200612-0302
2006
Delor, C.Da Rosa Costa, L., Lafon, J.M., Delor, C.Zircon geochronology and Sm Nd isotopic study: further constraints for the Archean and Paleoproterozoic geodynamical evolution of southe eastern Guiana Shield.Gondwana Research, Vol. 10, 3-4, pp. 277-300.South America, GuyanaGeochronology
DS201412-0934
2014
Delor, C.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
DS1991-0367
1991
Delor, C.P.Delor, C.P., Rock, N.M.S.Alkaline-ultramafic lamprophyre dykes from the Vestfold Hills, Princess Elizabeth Land (East Antarctica) -primitive magmas of deep mantle originAntarctic Science, Vol. 3, No. 4, December pp. 419-432. # GR092AntarcticaAlkaline, Lamprophyre dykes
DS202004-0506
2020
Delord, T.Delord, T., Huillery, P., Nicolas, L., Hetet, G.Spin-cooling of the motion of trapped diamond.Nature, March 23, in press available Globalnitrogen

Abstract: Observing and controlling macroscopic quantum systems has long been a driving force in quantum physics research. In particular, strong coupling between individual quantum systems and mechanical oscillators is being actively studied. Whereas both read-out of mechanical motion using coherent control of spin systems and single-spin read-out using pristine oscillators have been demonstrated, temperature control of the motion of a macroscopic object using long-lived electronic spins has not been reported. Here we observe a spin-dependent torque and spin-cooling of the motion of a trapped microdiamond. Using a combination of microwave and laser excitation enables the spins of nitrogen-vacancy centres to act on the diamond orientation and to cool the diamond libration via a dynamical back-action. Furthermore, by driving the system in the nonlinear regime, we demonstrate bistability and self-sustained coherent oscillations stimulated by spin-mechanical coupling, which offers the prospect of spin-driven generation of non-classical states of motion. Such a levitating diamond-held in position by electric field gradients under vacuum-can operate as a ‘compass’ with controlled dissipation and has potential use in high-precision torque sensing, emulation of the spin-boson problem15 and probing of quantum phase transitions. In the single-spin limit and using ultrapure nanoscale diamonds, it could allow quantum non-demolition read-out of the spin of nitrogen-vacancy centres at ambient conditions, deterministic entanglement between distant individual spins and matter-wave interferometry.
DS1986-0404
1986
Delorme, H.Javoy, M., Pineau, F., Delorme, H.Carbon and nitrogen isotopes in the mantleChem. Geol, Vol. 57, No. 1-2, pp. 41-62GlobalKimberlite, Mantle
DS1996-0355
1996
Delouis, B.Delouis, B., Cisternas, A., Kausel, E.The Andean subduction zone between 22 and 25 degrees (Northern Chile)precise geometry and state of stressTectonophysics, Vol. 259, No. 1-3, June 30, pp. 81-100ChileSubduction, Tectonics
DS1997-1112
1997
Deloule, E.Stone, W.E., Deloule, E., Larson, M.S., Lesher, C.M.Evidence for hydrous high MgO melts in the PrecambrianGeology, Vol. 25, No. 2, Feb. pp. 143-146Ontario, QuebecKomatiites, Abitibi belt
DS2003-0394
2003
Deloule, E.Faure, M., Lin, W., Monie, P., Le Breton, N., Pouissineau, S., Panis, D., Deloule, E.Exhumation tectonics of the ultrahigh pressure metamorphic rocks in the Qinling orogenTectonics, Vol. 22, 3, 10.1029/2002TC001450ChinaTectonics - subduction
DS2003-0395
2003
Deloule, E.Faure, M., Lin, W., Monie, P., Le Breton, N., Pouissineau, S., Panis, D., Deloule, E.Exhumation tectonics of the ultrahigh pressure metamorphic rocks in the Qinling orogenTectonics, Vol. 22, 3, 10.1029/2002TC001450China, ShandongUHP
DS2003-1436
2003
Deloule, E.Wagner, C., Mokhtari, A., Deloule, E., Chabaux, F.Carbonatite and alkaline magmatism in Taourirt: petrological, geochemical and Sr NdJournal of Petrology, Vol. 44, 5, pp. 937-65.MoroccoCarbonatite
DS200412-0537
2003
Deloule, E.Faure, M., Lin, W., Monie, P., Le Breton, N., Pouissineau, S., Panis, D., Deloule, E.Exhumation tectonics of the ultrahigh pressure metamorphic rocks in the Qinling orogen in east China: new petrological structuraTectonics, Vol. 22, 3, 10.1029/2002TC001450China, ShandongUHP
DS200412-2068
2003
Deloule, E.Wagner, C., Mokhtari, A., Deloule, E., Chabaux, F.Carbonatite and alkaline magmatism in Taourirt: petrological, geochemical and Sr Nd isotope characteristics.Journal of Petrology, Vol. 44, 5, pp. 937-65.Africa, MoroccoCarbonatite
DS200612-0246
2006
Deloule, E.Chen, D., Ni, T., Deloule, E., Li, B.Zircon Lu Hf and U Pb isotopic compositions in ultrahigh pressure eclogite from Dabie orogen eastern central China.Geochimica et Cosmochimica Acta, Vol. 70, 18, 1, p. 19, abstract only.ChinaUHP
DS200612-0305
2006
Deloule, E.Daogong, C., Deloule, E., Tao, Ni.Metamorphic zircon from Xindian eclogite, Dabie Terrain: U Pb age and oxygen isotope composition.Science China Earth Sciences, Vol. 49, 1, Jan. pp. 66-76.ChinaUHP - eclogite, Dabie Shan
DS200712-0172
2007
Deloule, E.Chen, D., Deloule, E., Li, B., Ni, T.Zircon Lu-Hf isotope and its significance to ultra high pressure metamorphic rocks from Dabie Terrain, Eastern China.Plates, Plumes, and Paradigms, 1p. abstract p. A164.ChinaUHP
DS200712-1126
2007
Deloule, E.Wagner, C., Deloule, E.Behaviour of Li and its isotopes during metasomatism of French Massif Central lherzolites.Geochimica et Cosmochimica Acta, Vol. 71, 17 Sept. 1, pp. 4279-4296.Europe, FranceMetasomatism
DS201312-0204
2013
Deloule, E.<