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SDLRC - Region: Tibet - All


The Sheahan Diamond Literature Reference Compilation - Technical, Media and Corporate Articles based on Major Region - Tibet
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 announcements called 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 Region Index
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
Each article reference in the SDLRC is tagged with one or more key words assigned by Pat Sheahan to highlight the main topics of the article. In addition most references have been tagged with one or more region words. In an effort to make it easier for users to track down articles related to a specific region, KRO has extracted these region words and developed a list of major region words presented in the Major Region Index to which individual region words used in the article reference have been assigned. Each individual Region Report contains in chronological order all the references with a region word associated with the Major Region word. Depending on the total for each reference type - technical, media and corporate - the references will be either in their own technical, media or corporate Region Report, or combined in a single report. Where there is a significant number of technical references there will be a technical report dedicated to the technical articles while the media and corporate references are combined in a separate region report. References that were added in the most recent monthly update are highlighted in yellow within the Region Report. The Major Region words have been defined by a scale system of "general", "continent", "country", "state or province" and "regional". Major Region words at the smaller scales have been created only when there are enough references to make isolating them worthwhile. References not tagged with a Region are excluded, and articles with a region word not matched with a Major Region show up in the "Unknown" report.
Kimberlite - diamondiferous Lamproite - diamondiferous Lamprophyre - diamondiferous Other - diamondiferous
Kimberlite - non diamondiferous Lamproite - non diamondiferous Lamprophyre - non diamondiferous Other - non diamondiferous
Kimberlite - unknown Lamproite - unknown Lamprophyre - unknown Other - unknown
Future Mine Current Mine Former Mine Click on icon for details about each occurrence. Works best with Google Chrome.
CITATION: Faure, S, 2010, World Kimberlites CONSOREM Database (Version 3), Consortium de Recherche en Exploration Minérale CONSOREM, Université du Québec à Montréal, Numerical Database on consorem.ca. NOTE: This publicly available database results of a compilation of other public databases, scientific and governmental publications and maps, and various data from exploration companies reports or Web sites, If you notice errors, have additional kimberlite localizations that should be included in this database, or have any comments and suggestions, please contact the author specifying the ID of the kimberlite: [email protected]
Tibet - Technical, Media and Corporate
Posted/
Published
AuthorTitleSourceRegionKeywords
DS1980-0028
1980
Anon.Natural Diamond Discovered in Ultrabasic Rock in TibetXinhua News Bulletin., MAY 29TH. ALSO: LONDON MINING JOURNAL, JUNE 13TH. P. 483 198China, TibetDiamond Occurrences, Ultramafic Rocks, Chromiferous Peridotite
DS1982-0648
1982
Yan binggang, SUN DESHO.The Character of Diamonds in Ultrabasic Rocks in Xizang (tibet).Bulletin. Institute GEOL. (CHINESE ACAD. GEOL. SCI.), No. 5, P. 64.China, TibetDiamond Morphology
DS1989-1044
1989
Molnar, P.The geologic evolution of the Tibetan Plateau. What processes have builtsuch a high region with so little topographical relief?Phil. Transactions Royal Soc. London, Vol. 328, No. 1599, July 4, pp. 350-360TibetTectonics, Plateau
DS1990-0580
1990
Global Geoscience transectsGlobal geoscience transectsA.g.u, Syria, China, Tibet, Brazil, Australia, Andes, Chile, ArgentinaGeophysics, Remote sensing
DS1992-0355
1992
Deng Wanminghigh pressureotassium volcanic rocks and its origins at North TibetInternational Symposium Cenozoic Volcanic Rocks Deep seated xenoliths China and its, Abstracts pp. 114-116China, TibetLatites, shoshonites, Alkalic rocks
DS1993-0064
1993
Bai, W.J., Robinson, P.T., Zhou, M.Diamond -bearing peridotites from Tibetan ophiolites: implications for a subduction related origin of diamondsMid-continent diamonds Geological Association of Canada (GAC)-Mineralogical Association of Canada (MAC) Symposium ABSTRACT volume, held Edmonton May, pp. 77-84China, TibetOphiolites
DS1993-1708
1993
Wen-Ji Bai, Mei-Fu Zhou, Robinson, P.T.Possible diamond bearing mantle peridotites and podiform chromitites in the Luobusa and Donqiao ophiolites, Tibet.Canadian Journal of Earth Sciences, Vol. 30, No. 8, August pp. 1650-1659.TibetDiamond bearing, Peridotites, ophiolites
DS1994-1387
1994
Platt, J.P., England, P.C.Convective removal of lithosphere beneath mountain belts: thermal and mechanical consequenesAmerican Journal of Science, Vol. March pp. 307-336Cordillera, Basin and Range, TibetTectonics, Mountain belts
DS1995-1457
1995
Pearson, D.G., Davies, G.R., Nixon, P.H.Orogenic ultramafic rocks of ultra high pressure (UHP) (diamond facies) originCambridge University of Press, pp. 456-510.Morocco, Spain, British Columbia, Russia, Tibet, Burkina FasoPeridotite - Beni Bousera, Ronda, Ophiolites - diamondiferous
DS1995-1889
1995
Taylor, W.R., Milledge, H.J., Griffen, W.L., Nixon, P.h.Characteristics of microdiamonds from ultramafic massifs in Tibet:authentic ophiolitic diamonds.....Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 623-624.China, TibetMicrodiamonds, Metamorphic
DS1996-0322
1996
Daizhi, L.Study on the dynamic mechanism of the Qinghai-Xizang (Tibet) PlateauupliftGlobal Tectonics and Metallogeny, Vol. 6, No. 1, pp. 9-17China, TibetGeodynamics, Plateau uplift
DS1996-0813
1996
Lave, J., Avouac, J.P., Montagner, J.P.Seismic anisotropy beneath Tibet: evidence for eastward extrusion of the Tibetan lithosphere.Earth and Planetary Science Letters, Vol. 140, No. 1-4, May 1, pp. 83-96.China, TibetGeophysics -seismics, Lithosphere
DS1996-1555
1996
Wittlinger, G., Masson, F., et al.Seismic tomography of north Tibet and Kunlun: evidence for crustal blocksand mantle velocity contrastsEarth and Planetary Science Letters, Vol. 139, pp. 2630279.China, TibetTomography, Mantle tectonics, blocks
DS1998-0645
1998
Hu, Xu-Feng, Robinson, P.T.Mineralogy, of diamond bearing chromitites, Luobusa ophiolite, southernTibet.Geological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) Abstract Volume, p. A81. abstract.China, TibetOphiolite - Luobusa, Mineralogy
DS1998-1581
1998
Willett, S.D.Geodynamic modelling and insight into deep crustal processesGeological Society of America (GSA) Annual Meeting, abstract. only, p.A243.Europe, Tibet, AndesStructure, tectonics
DS1999-0379
1999
Kosarev, G., Kind, R., Oreshin, S.Seismic evidence for a detached Indian lithospheric mantle beneath TibetScience, Vol. 285, No. 5406, Feb. 26, pp. 1306-9.China, Tibet, IndiaGeophysics - seismics, Lithosphere
DS2000-0417
2000
Hoke, L., Lamb, S., Poreda, R.J.Southern limit of mantle derived geothermal helium emissions in Tibet: implications for lithospheric ...Earth and Planetary Science Letters, Vol. 180, No. 3-4, pp.297-308.Tibet, MantleGeothermometry
DS2000-0863
2000
Schaefer, B.F., Turner, S.P., Rogers, Hawkesworth et al.Rhenium- Osmium (Re-Os) isotope characteristics of postorogenic lavas: implications for nature of young lithospheric mantle...Geology, Vol. 28, No. 6, June pp. 563-6.Colorado Plateau, Tibet, SpainGeochronology - potassic lavas, Mantle depletion - basaltic magmas
DS2000-1035
2000
Xu-Feng, H., Robinson, P.T., Wenji Bai, ZhouDiamonds in ophiolites - fact or fictionGeological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) Calgary May 2000, 3p.China, TibetOphiolite - Luobusa, podiforM.
DS2001-0072
2001
Bai, W. Yang, Robinson, Febg, Zhang, Yan, HuStudy of diamonds from chromitites in the Luobusa ophiolite, TibetActa Geologica Sinica, Vol. 75, No. 3, pp. 409-17.China, TibetChromitites - diamond
DS2001-0569
2001
Kao, H., et al.Seismic imaging of the Tarim basin and its collision with TibetGeology, Vol. 19, No. 7, July pp. 575-8.China, TibetGeophysics - seismics
DS2001-1240
2001
Williams, H., Turner, S., Kelley, S., Harris, N.Age and composition of dikes in Southern Tibet: new constraints on the timing of east west extension ...Geology, Vol. 29, No. 4, Apr. pp.339-42.Tibetvolcanism - post collisional, Geodynamics
DS2001-1273
2001
Xu, Y.G., Menzies, M.A., Thirwall, M.F., Xie, G.H.Exotic lithosphere mantle beneath the western Yangtze craton: petrogenetic links to Tibet using ultrapotassicGeology, Vol. 29, No. 9, Sept. pp. 863-866.China, Tibet, Asiaultra high pressure (UHP), ultrapotassic highly magnesian, Metasomatism
DS2002-0755
2002
Jackson, J.Faulting, flow and the strength of the continental lithosphereInternational Geology Review, Vol. 44, 1, pp. 39-61.India, China, TibetTectonics - structure
DS2002-0756
2002
Jackson, J.Strength of the continental lithosphere: time to abandon the jelly sandwich?Gsa Today, Sept. pp. 4-9.India, China, TibetTectonics, geodynamics, lithosphere
DS2002-0782
2002
Jingsui, Y., Zhiqin, X., Jianxin, Z., Shugang, S.Early Paleozoic North Qaidam UHP metamorphic belt on the north eastern Tibetan plateau and a paired subduction model.Terra Nova, Vol. 14, 5, Oct. pp. 397-404.China, TibetUHP - Ultrahigh pressure, subduction
DS2002-0943
2002
Li, X.H., Zhou, H., Chung, S.L., Lo, Ch., Wei, G., Liu, Y., Lee, C.Geochemical and Sr Nd isotopic characteristics of Late Paleogene ultrapotassic magmatism in southeast Tibet.International Geology Review, Vol. 44, 6, pp. 559-74.TibetGeochemistry, geochronology, magmatism
DS2002-1745
2002
Xiao, W.J., Windley, B.F., Chen, H.L.,Zhang, G.C., LiCarboniferous Triassic subduction and accretion in the western Kunln: implications for collisional tectonics..Geology, Vol. 30,4,Apr.pp.295-8.China, TibetTectonics - accretionary
DS2003-0351
2003
Dricker, I.G., Roecker, S.W.Lateral heterogeneity in the upper mantle beneath the Tibetan plateau and itsJournal of Geophysical Research, Vol. 107, 11, Nov. 6, pp. DO1 10.1029/2001JB000797China, TibetGeophysics - seismics
DS2003-1382
2003
Tilmann, F., Ni, J.Seismic imaging of the downwelling Indian lithosphere beneath central TibetScience, No. 5624, Nay 30, pp. 1424-26.China, Tibet, Asia, IndiaGeophysics - seismics
DS200412-0484
2003
Dricker, I.G., Roecker, S.W.Lateral heterogeneity in the upper mantle beneath the Tibetan plateau and its surroundings from SS-S travel time residuals.Journal of Geophysical Research, Vol. 107, 11, Nov. 6, pp. DO1 10.1029/2001 JB000797China, TibetGeophysics - seismics
DS200412-1634
2002
Ravikant, V.Ultrapotassic post collisional dyke from the Laddakh Batholith, Northwest Himalaya.Journal Geological Society of India, Vol. 59, 5, pp. 473-476.India, TibetShoshonite petrography, tectonic, reactivation
DS200412-1879
2004
Song, S., Zhang, L., Niu, Y.Ultra deep origin of garnet peridotite from north Qaidam ultrahigh pressure belt, northern Tibetan Plateau, NW China.American Mineralogist, Vol. 89, 7, pp. 1330-36.China, TibetUHP
DS200412-1996
2003
Tilmann, F., Ni, J.Seismic imaging of the downwelling Indian lithosphere beneath central Tibet.Science, No. 5624, Nay 30, pp. 1424-26.China, Tibet, Asia, IndiaGeophysics - seismics
DS200412-2023
2004
Unsworth, M., Wenbo, W., Jones, A.G., Li, S., Bedrosian, P., Booker, J., Sheng, J., Ming, D., Handong, T.Crustal and upper mantle structure of northern Tibet imaged with magnetotelluric data.Journal of Geophysical Research, Vol. 109, B2, Feb. 13, 10.1029/2002 JB002305Asia, TibetTectonics, geophysics - seismics
DS200412-2096
2003
Wei, Q., Wang, J., Xie, G.The chemical composition characteristics of clinopyroxenes from spinel lherzolite xenoliths in Maguan area, Eastern Tibet and itEarth Science Frontiers, Vol. 10, 3, pp. 87-92. Ingenta 1035303170China, TibetXenoliths - not specific to diamonds
DS200512-0381
2004
Guo, Z., Hertogen, J., Liu, J., Pasteels, P., Vocen, A.Potassic magmatism in western Sichuan and Yunnan Provinces, SE Tibet, China: petrological and geochemical constraints on petrogenesis.Journal of Petrology, Vol. 46, 1-2, pp. 33-78.China, TibetMagmatism
DS200512-0479
2005
Jiang, X., Jin, Y.Mapping the deep lithospheric structure beneath the eastern margin of the Tibetan Plateau from gravity anomalies.Journal of Geophysical Research, Vol. 110, B7, B07407 10.1029/2004 JB003394Asia, TibetGeophysics - gravity
DS200512-0814
2005
Ozacar, A.A., Zandt, G.Crustal seismic anisotropy in central Tibet: implications for deformational style and flow in the crust.Geophysical Research Letters, Vol. 31, 23, Dec. 16, DOI 10.1029/2004 GLO21096Asia, TibetGeophysics - seismics
DS200512-1027
2005
Song, S., Zhang, L., Niu, Y., Su, L., Jian, P., Liu, D.Geochronology of diamond bearing zircons from garnet peridotite in the North Qaidam UHPM belt, Northern Tibetan Plateau: a record of lithospheric subduction.Earth and Planetary Science Letters, Vol. 234, 1-2, pp. 99-118.Asia, TibetGeochronology
DS200512-1034
2005
Spratt, J.E., Jones, A.G., Nelson, K.D., Unsworth, M.J., INDEPTH MT TeamCrustal structure of the India - Asia collision zone, southern Tibet, from INDEPTH MT investigations.Physics of the Earth and Planetary Interiors, India, Asia, TibetGeophysics, EM and magnetotelluric
DS200512-1210
2004
Xu, Z., Jiang, M., Yang, J.Mantle structure of Qinghai Tibet Plateau: mantle plume, mantle shear zone and delamination of lithospheric slab.Earth Science Frontiers, Vol. 11, 4, pp. 329-344. Ingenta 1045384775China, TibetSubduction
DS200512-1258
2005
Zheng Fu, G., Hertogen, J., Liu, J., Pasteels, A., Boven, L., Punzalan, H., Xiangiun, L., Zhang, W.Potassic magmatism in western Sichuan and Yunnan Provinces, SE Tibet, China: petrological and geochemical constraints on petrogenesis.Journal of Petrology, Vol. 46, 1, pp. 33-78.China, TibetMagmatism
DS200612-0207
2006
Cai, L., Qingguo, Z., Yonsheng, D., Xiaopeng, H.Discovery of eclogite and its geological significance in Qiantang central Tibet.Chinese Science Bulletin, Vol. 51, 9, May pp. 1095-1100.China, TibetEclogite, tectonics
DS200612-0513
2006
Guo, Z., Wilson, M., Liu, J., Mao, Q.Post collisional, potassic and ultrapotassic magmatism of the northern Tibetan Plateau: constraints on characteristics of the mantle source, geodynamic upliftJournal of Petrology, Vol. 47, 6, pp. 1177-1220.Asia, TibetMagmatism - not specific to diamonds
DS200712-1198
2007
Yang, J-S., Dobrzhinetskaya, L.Diamond and coesite bearing chromitites from the Luobusa ophiolite, Tibet.Geology, Vol. 35, 10, Oct. pp. 875-878.Asia, TibetUHP
DS200812-0482
2008
Holbig, E.S., Grove, T.L.Mantle melting beneath the Tibetan Plateau: experimental constraints on ultrapotassic magmatism.Journal of Geophysical Research, Vol. 113, B4, B04210Asia, TibetMelting
DS200812-0557
2008
Kerr, R.Pumping up the Tibetan Plateau from the far Pacific Ocean.Science, Vol. 321 no. 5892 pp. 1028-1029.Asia, TibetTectonics
DS200812-0661
2008
Li,C., Vander Hilst, R., Meltzer, A.S., Engdahl, E.R.Subduction of the Indian lithosphere beneath the Tibetan Plateau and Burma.Earth and Planetary Science Letters, Vol. 274, 1-2, pp. 157-168.Asia, Tibet, MyanmarSubduction
DS200812-0977
2008
Royden, L.H., Burchfiel, B.C., Van der Hilst, R.D.The geological evolution of Tibetan Plateau.Science, Vol. 321, no. 5892, August 22, pp. 1054-1058.Asia, TibetTectonics
DS200812-1053
2008
Shi, R.D., Ding, B.H., Zhi, X.C., Zhao, G.C.Re Os isotope constraints on the genesis of the Luliangshan garnet peridotites in the North Qaidam UHP belt, Tibet.Goldschmidt Conference 2008, Abstract p.A857.Asia, TibetUHP
DS200812-1300
2008
Yu, X., Zhao, Z., Mo, X., Dong, G.Cenozoic alkaline and carbonatitic magmatism in northeastern Tibetan Plateau: implications for mantle plume.Goldschmidt Conference 2008, Abstract p.A1065.Asia, TibetCarbonatite
DS200912-0106
2009
Chan, G.H.N., Waters, D.J., Searle, M.P., Aitchison, J.C., Horstwood, M.S.A., Crowley, Q., Lo, C.H., Chan J.Probing the basement of southern Tibet: evidence from crustal xenoliths entrained in a Miocene ultrapotassic dyke.Journal of the Geological Society, Vol. 166, 1, pp. 45-52.Asia, TibetAlkalic
DS201012-0643
2010
Ruskov, T., Spirov, I., Georgieva, M., Yamamoto, S., Green, H.W., McCammon, C.A., Dobrzhinetskaya, L.F.Mossbauer spectroscopy studies of the valence state of iron in chromite from the Luobusa Massif of Tibet: implications for a highly reduced mantle.Journal of Metamorphic Geology, Vol. 28, 5, pp. 551-560.Asia, TibetMetasomatism
DS201012-0872
2010
Yang, J., Zhang, Z., Xu, X., Li, Y., Li, J., Jia, Y., Liu, Z., Ba, D.Diamond in the Purang peridotite Massif, west of the Yarlung Zangbu Suture, Tibet: a new discovery.Goldschmidt 2010 abstracts, abstractAsia, TibetPurang Massif
DS201112-0024
2011
Arai, S., Ahmed, A.H., Miura, M.Ultrahigh pressure podiform chromitites as a possible deep recycled material.Goldschmidt Conference 2011, abstract p.447.Asia, Tibet, OmanUHP
DS201112-0871
2004
Robinson, P.T., Bai, W-J., Malpas, J., Yang, J-S., Zhou, M-F., Fang, Q-S., Hu, X-F., Cameron, StaudigelUltra high pressure minerals in the Loubasa ophiolite, Tibet and their tectonic implications.Aspects of the Tectonic evolution of China, Editors Fletcher, Ali, Aitchison, Geological Society Of America, Spec. Pub.226, pp.247-71China, TibetUHP
DS201112-1132
2011
Yang, J.S., Robinson, P.T.In situ diamonds and moissanite in podiform chromitites of the Loubusa and Ray-Iz ophiolites, Tibet and Russia.Goldschmidt Conference 2011, abstract p.2209.Russia, Asia, TibetDiamonds
DS201212-0801
2012
Yang, J., Wirth, R., Xu, X., Robinson, P.T., Rong, H.Mineral inclusions in diamonds from ophiolitic peridotite and chromites.GSA Annual Meeting, Paper no. 74-4, abstractChina, TibetDiamond inclusions
DM201309-2255
2013
MinewebNew mineral, Qingsongite, only inferior to diamonds in hardness.Mineweb.com, August 5, 1p.China, TibetNews item - Qingsongite
DS201312-0337
2013
Griffin, W.L., Yang, J.S., Robinson, P., Howell, D., Shi, R., O'Reilly, S.Y., Pearson, D.J.Diamonds and super reducing UHP assemblages in ophiolitic mantle, Tibet: where are the eclogites?X International Eclogite Conference, 1p. abstractAsia, TibetDiamond genesis
DS201312-0810
2013
Shi, R.D., Griffin, W.L., O'Reilly, S.Y., Zhang, X.R., Huang, Q.S., Gong, X.H., Ding, L.Geodynamic constraints on the recycling of ancient SCLM and genesis of Tibetan Diamondiferous ophiolites.Goldschmidt 2013, 1p. AbstractAsia, TibetOphiolites
DS201312-0811
2013
Shi, R.D., Griffin, W.L., O'Reilly, S.Y., Zhang, X.R., Huang, Q.S., Gong, X.H., Ding, L.Recycling of ancient SCLM and genesis of Tibetan Diamondiferous ophiolites.Goldschmidt 2013, AbstractAsia, TibetOphiolites
DS201412-0092
2014
Campbell, I., Stepanov, A., Liang, H-Y., Allen, C., Norman, M., Zhang, Y-Q, Xie, Y-W.The origin of shoshonites: new insights from the Tertiary high-potassium intrusions of eastern Tibet.Contributions to Mineralogy and Petrology, Vol. 167, 3, pp. 1-22.Asia, TibetShoshonite
DS201412-0382
2014
Huang, M-X., Yang, J-J., Powell, R., Mo, X.High pressure metamorphism of serpentinzed chromitite at Luobusha ( southern Tibet).American Journal of Science, Vol. 314, pp. 400-433.Asia, TibetDiamond and coesite
DS201412-0512
2014
Liang, F., Xu, Z., Zhao, J.In-situ moissanite in dunite: deep mantle Luobusa ophiolite, Tibet.Acta Geologica Sinica, Vol. 88, 2, pp. 517-529.Asia, TibetMoissanite
DS201412-0517
2014
Liu, D., Zhao, Z., Zhu, D-C., DePaolo, D.J., Harrison, T.M., Mo, X., Dong, G., Zhou, S., Sun, C., Zhang, Z., Liu, J.Post collisional potassic and ultrapotassic rocks in southern Tibet: mantle and crustal origins in response to India-Asia collision and convergence.Geochimica et Cosmochimica Acta, Vol. 143, pp. 207-231.Asia, TibetAlkalic
DS201412-0518
2014
Liu, D., Zhao, Z., Zhu, D-C., Niu, Y., Harrison, T.M.Zircon xenocrysts in Tibetan ultrapotassic magmas: imaging the deep crust through time.Geology, Vol. 42, pp. 43-46.Asia, TibetGeochronology
DS201412-0999
2014
Yang, J., Meng, F., Xu, X., Robinson, P.T., Dilek, Y., Makeyev, A.B., Wirth, R., Wiedenbeck, M., Cliff, J.Diamonds, native elements and metal alloys from chromitites of the Ray-Iz ophiolite of the Polar Urals.Gondwana Research, Vol. 27, 2, pp. 459-485.Asia, TibetUHP ophiolite diamonds
DS201504-0231
2015
Xiong, Q., Griffin, W.L., Zheng, J-P., O'Reilly, S.Y., Pearson, N.J.Episodic refertilization and metasomatism of Archean mantle: evidence from an orogenic peridotite in North Qaidam ( NE Tibet) China.Contributions to Mineralogy and Petrology, Vol. 169, 24p.China, TibetPeridotite
DS201601-0049
2015
Xiong, F., et al.Diamond discovered in Dangqiong ophiolite, western Yarlung-Zangbu suture zone, Tibet.Acta Geologica Sinica, Vol. 89, 2, pp. 99-100.Asia, TibetOphiolite
DS201603-0382
2016
Griffin, W.L., Gain, S.E.M., Adams, D., Toledo, V., Pearson, N.J., O'Reilly, S.Y.Deep-Earth methane, mantle dynamics and mineral exploration: insights from northern Israel, southern Tibet and Kamchatka.Israel Geological Society, pp. 87-88. abstractEurope, Israel, TibetMoissanite
DS201605-0922
2016
Xiong, F., Yang, J., Robinson, P.T., Xu, X., Ba, D., Li, Y., Zhang, Z., Rong, H.Diamonds ad other exotic minerals recovered from peridotites of the Dangqiong ophiolite, western Yarlung-Zangbo suture zone, Tibet.Acta Geologica Sinica, Vol. 90, 2, pp. 425-439.Asia, TibetPeridotite

Abstract: Various combinations of diamond, moissanite, zircon, quartz, corundum, rutile, titanite, almandine garnet, kyanite, and andalusite have been recovered from the Dangqiong peridotites. More than 80 grains of diamond have been recovered, most of which are pale yellow to reddish-orange to colorless. The grains are all 100-200 µm in size and mostly anhedral, but with a range of morphologies including elongated, octahedral and subhedral varieties. Their identification was confirmed by a characteristic shift in the Raman spectra between 1325 cm?1 and 1333 cm?1, mostly at 1331.51 cm?1 or 1326.96 cm?1. Integration of the mineralogical, petrological and geochemical data for the Dongqiong peridotites suggests a multi-stage formation for this body and similar ophiolites in the Yarlung-Zangbo suture zone. Chromian spinel grains and perhaps small bodies of chromitite crystallized at various depths in the upper mantle, and encapsulated the UHP, highly reduced and crustal minerals. Some oceanic crustal slabs containing the chromian spinel and their inclusion were later trapped in suprasubduction zones (SSZ), where they were modified by island arc tholeiitic and boninitic magmas, thus changing the chromian spinel compositions and depositing chromitite ores in melt channels.
DS201606-1090
2016
Griffin, W.L., Afonso, J.C., Belousova, E.A., Gain, S.E., Gong, X-H., Gonzalez-Jiminez, J.M., Howell, D., Huang, J-X., McGowan, N., Pearson, N.J., Satsukawa, T., Shi R., Williams, P., Xiong, Q., Yang, J-S., Zhang, M., O'Reilly, S.Y.Mantle recycling: transition zone metamorphism of Tibetan ophiolitic peridotites and its tectonic implications.Journal of Petrology, in press available, 30p.Asia, China, TibetPeridotite

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

Abstract: For more than 20 years, the reported occurrence of diamonds in the chromites and peridotites of the Luobusa massif in Tibet (a complex described as an ophiolite) has been widely ignored by the diamond research community. This skepticism has persisted because the diamonds are similar in many respects to high-pressure high-temperature (HPHT) synthetic/industrial diamonds (grown from metal solvents), and the finding previously has not been independently replicated. We present a detailed examination of the Luobusa diamonds (recovered from both peridotites and chromitites), including morphology, size, color, impurity characteristics (by infrared spectroscopy), internal growth structures, trace-element patterns, and C and N isotopes. A detailed comparison with synthetic industrial diamonds shows many similarities. Cubo-octahedral morphology, yellow color due to unaggregated nitrogen (C centres only, Type Ib), metal-alloy inclusions and highly negative View the MathML source?C13 values are present in both sets of diamonds. The Tibetan diamonds (n=3n=3) show an exceptionally large range in View the MathML source?N15 (?5.6 to +28.7‰+28.7‰) within individual crystals, and inconsistent fractionation between {111} and {100} growth sectors. This in contrast to large synthetic HPHT diamonds grown by the temperature gradient method, which have with View the MathML source?N15=0‰ in {111} sectors and +30‰+30‰ in {100} sectors, as reported in the literature. This comparison is limited by the small sample set combined with the fact the diamonds probably grew by different processes. However, the Tibetan diamonds do have generally higher concentrations and different ratios of trace elements; most inclusions are a NiMnCo alloy, but there are also some small REE-rich phases never seen in HPHT synthetics. These characteristics indicate that the Tibetan diamonds grew in contact with a C-saturated Ni-Mn-Co-rich melt in a highly reduced environment. The stable isotopes indicate a major subduction-related contribution to the chemical environment. The unaggregated nitrogen, combined with the lack of evidence for resorption or plastic deformation, suggests a short (geologically speaking) residence in the mantle. Previously published models to explain the occurrence of the diamonds, and other phases indicative of highly reduced conditions and very high pressures, have failed to take into account the characteristics of the diamonds and the implications for their formation. For these diamonds to be seriously considered as the result of a natural growth environment requires a new understanding of mantle conditions that could produce them.
DS201608-1450
2016
Wang, R., Collins, W.J., Weinberg, R.F., Li, J-X., Li, Q-Y., He, W-Y., Richards, J.P., Hou, Z., Zhou, Li-M., Stern, R.A.Xenoliths in ultrapotassic volcanic rocks in the Lhasa block: direct evidence for crust mantle mixing and metamorphism in the deep crust.Contributions to Mineralogy and Petrology, in press available 19p.Asia, TibetMelting

Abstract: Felsic granulite xenoliths entrained in Miocene (~13 Ma) isotopically evolved, mantle-derived ultrapotassic volcanic (UPV) dykes in southern Tibet are refractory meta-granitoids with garnet and rutile in a near-anhydrous quartzo-feldspathic assemblage. High F-Ti (~4 wt.% TiO2 and ~3 wt.% F) phlogopite occurs as small inclusions in garnet, except for one sample where it occurs as flakes in a quartz-plagioclase-rich rock. High Si (~3.45) phengite is found as flakes in another xenolith sample. The refractory mineralogy suggests that the xenoliths underwent high-T and high-P metamorphism (800-850 °C, >15 kbar). Zircons show four main age groupings: 1.0-0.5 Ga, 50-45, 35-20, and 16-13 Ma. The oldest group is similar to common inherited zircons in the Gangdese belt, whereas the 50-45 Ma zircons match the crystallization age and juvenile character (?Hfi +0.5 to +6.5) of Eocene Gangdese arc magmas. Together these two age groups indicate that a component of the xenolith was sourced from Gangdese arc rocks. The 35-20 Ma Miocene ages are derived from zircons with similar Hf-O isotopic composition as the Eocene Gangdese magmatic zircons. They also have similar steep REE curves, suggesting they grew in the absence of garnet. These zircons mark a period of early Miocene remelting of the Eocene Gangdese arc. By contrast, the youngest zircons (13.0 ± 4.9 Ma, MSWD = 1.3) are not zoned, have much lower HREE contents than the previous group, and flat HREE patterns. They also have distinctive high Th/U ratios, high zircon ?18O (+8.73-8.97 ‰) values, and extremely low ?Hfi (?12.7 to ?9.4) values. Such evolved Hf-O isotopic compositions are similar to values of zircons from the UPV lavas that host the xenolith, and the flat REE pattern suggests that the 13 Ma zircons formed in equilibrium with garnet. Garnets from a strongly peraluminous meta-tonalite xenolith are weakly zoned or unzoned and fall into four groups, three of which are almandine-pyrope solid solutions and have low ?18O (+6 to 7.5 ‰), intermediate (?18O +8.5 to 9.0 ‰), and high ?18O (+11.0 to 12.0 ‰). The fourth is almost pure andradite with ?18O 10-12 ‰. Both the low and intermediate ?18O groups show significant variation in Fe content, whereas the two high ?18O groups are compositionally homogeneous. We interpret these features to indicate that the low and intermediate ?18O group garnets grew in separate fractionating magmas that were brought together through magma mixing, whereas the high ?18O groups formed under high-grade metamorphic conditions accompanied by metasomatic exchange. The garnets record complex, open-system magmatic and metamorphic processes in a single rock. Based on these features, we consider that ultrapotassic magmas interacted with juvenile 35-20 Ma crust after they intruded in the deep crust (>50 km) at ~13 Ma to form hybridized Miocene granitoid magmas, leaving a refractory residue. The ~13 Ma zircons retain the original, evolved isotopic character of the ultrapotassic magmas, and the garnets record successive stages of the melting and mixing process, along with subsequent high-grade metamorphism followed by low-temperature alteration and brecciation during entrainment and ascent in a late UPV dyke. This is an excellent example of in situ crust-mantle hybridization in the deep Tibetan crust.
DS201702-0225
2017
Liu, Y., Hou, Z.A synthesis of mineralization styles with an integrated genetic model of carbonatite syenite hosted REE deposits in the Cenozoic Mianning Dechang REE Metalogenetic belt, the eastern Tibetan Plateau, southwestern China.Journal of Asian Earth Sciences, in press available, 134p.China, TibetCarbonatite

Abstract: The Cenozoic Mianning-Dechang (MD) rare earth element (REE) belt in eastern Tibet is an important source of light REE in southwest China. The belt is 270 km long and 15 km wide. The total REE resources are >3 Mt of light rare earth oxides (REO), including 3.17 Mt of REO at Maoniuping (average grade = 2.95 wt.%), 81,556 t at Dalucao (average grade = 5.21 wt.%), 0.1 Mt at Muluozhai (average grade = 3.97 wt.%), and 5764 t of REO at Lizhuang (average grade = 2.38 wt.%). Recent results from detailed geological surveys, and studies of petrographic features, ore-forming ages, ore forming conditions, and wallrock alteration are synthesized in this paper. REE mineralization within this belt is associated with carbonatite-syenite complexes, with syenites occurring as stocks intruded by carbonatitic sills or dikes. The mineralization is present as complex vein systems that contain veinlet, stringer, stockwork, and brecciated pipe type mineralization. Carbonatites in these carbonatite-related REE deposits (CARDs) are extremely rich in light REEs, Sr (>5000 ppm), and Ba (>1000 ppm), and have low Sr/Ba and high Ba/Th ratios, and radiogenic Sr-Nd isotopic compositions. These fertile magmas, which may lead to the formation of REE deposits, were generated by the partial melting of sub-continental lithospheric mantle (SCLM) that was metasomatized by REE- and CO2-rich fluids derived from subducted marine sediments. We suggest that this refertilization occurred along cratonic margins and, in particular, at a convergent margin where small-volume carbonatitic melts ascended along trans-lithospheric faults and transported REEs into the overlying crust, leading to the formation of the CARDs. The formation of fertile carbonatites requires a thick lithosphere and/or high pressures (>25 kbar), a metasomatized and enriched mantle source, and favorable pathways for magma to ascend into the overlying crust where REE-rich fluids exsolve from cooling magma. The optimal combination of these three factors only occurs along the margins of a craton with a continental root, rather than in modern subduction zones where the lithosphere is relatively thin. U-Pb zircon dating indicates that the Maoniuping, Lizhuang, and Muluozhai alkali igneous complexes in the northern part of the belt formed at 27-22 Ma, whereas the Dalucao complex in the southern part of the belt formed at 12-11 Ma. Biotite and arfvedsonite in Lizhuang and Maoniuping REE deposit have 40Ar/39Ar ages of 30.8 ± 0.4 Ma (MSWD = 0.98) and 27.6 ± 2.0 Ma (MSWD = 0.06), respectively. Biotitaion alteration in syenite and fenitization caused by the relatively amount of carbonatite on syenite and host rocks is the main alteration along the whole belt. Initial Sr (0.7059-0.7079), 143Nd/144Nd (0.5123-0.5127), and 207Pb/204Pb (15.601-15.628) and 208Pb/204Pb (38.422-38.604) isotopic compositions of fluorite, barite, celestite, and calcite in the MD belt are similar to those of the associated syenite and carbonatite. Given the relatively high contents of Cl, F, SO42-, and CO2 in the rocks of the complexes, it is likely that the REEs were transported by these ligands within hydrothermal fluids, and the presence of bastnäsite indicates that the REEs were precipitated as fluorocarbonates. Petrographic, fluid inclusion, and field studies of the ores indicate that bastnäsite and other REE minerals formed during the final stages (<300°C) of the evolution of magmatic-hydrothermal systems in the belt. The mineralization formed from magmatic and meteoric fluids containing CO2 derived from the decarbonation of carbonatite, as indicated by C-O isotopic values of hydrothermal calcite and bastnäsite (?13C= -4.8 to -8.7 and ?18O = 5.8 to 12.5 ‰) and O-H isotopic values of quartz (330°C) and arfvedsonite (260°C), which correspond to fluid isotope compositions of ?18O = 0.3 to 9.8‰ and ?D = -70.0 to -152.8‰ in the belt. This study indicates that formation the largest REE deposits are related to voluminous carbonatite-syenite complexes, compositionally similar ore-forming fluids, extensive alteration, multiple stages of REE mineralization, and tectonic setting.
DS201702-0254
2017
Xu, B., Griffin, W.L., Xiong, Q., Hou, Z-Q, O'Reilly, S.Y., Guo, Z., Pearson, N.J., Greau, Y., Yang, Z-M., Zheng, Y-C.Ultrapotassic rocks and xenoliths from South Tibet: contrasting styles of interaction between lithospheric mantle and asthenosphere during continental collision.Geology, Vol. 45, 1, pp. 51-54.China, TibetUPR - metasomatism

Abstract: Widespread Miocene (24-8 Ma) ultrapotassic rocks and their entrained xenoliths provide information on the composition, structure, and thermal state of the sub-continental lithospheric mantle in southern Tibet during the India-Asia continental collision. The ultrapotassic rocks along the Lhasa block delineate two distinct lithospheric domains with different histories of depletion and enrichment. The eastern ultrapotassic rocks (89°E-92°E) reveal a depleted, young, and fertile lithospheric mantle (87Sr/86Srt = 0.704-0.707 [t is eruption time]; Hf depleted-mantle model age [TDM] = 377-653 Ma). The western ultrapotassic rocks (79°E-89°E) and their peridotite xenoliths (81°E) reflect a refractory harzburgitic mantle refertilized by ancient metasomatism (lavas: 87Sr/86Srt = 0.714-0.734; peridotites: 87Sr/86Srt = 0.709-0.716). These data integrated with seismic tomography suggest that upwelling asthenosphere was diverted away from the deep continental root beneath the western Lhasa block, but rose to shallower depths beneath a thinner lithosphere in the eastern part. Heating of the lithospheric mantle by the rising asthenosphere ultimately generated the ultrapotassic rocks with regionally distinct geochemical signatures reflecting the different nature of the lithospheric mantle.
DS201704-0636
2017
Liu, Y., Hou, Z.A synthesis of minerlization styles with an integrated genetic model of carbonatite syenite hosted REE deposits in the Cenozoic Mianning Dechang REE metallogenic belt, the eastern Tibetan Plateau, southwestern China.Journal of Asian Earth Sciences, Vol. 137, pp. 35-79.China, TibetCarbonatite

Abstract: he Cenozoic Mianning-Dechang (MD) rare earth element (REE) belt in eastern Tibet is an important source of light REE in southwest China. The belt is 270 km long and 15 km wide. The total REE resources are >3 Mt of light rare earth oxides (REO), including 3.17 Mt of REO at Maoniuping (average grade = 2.95 wt.%), 81,556 t at Dalucao (average grade = 5.21 wt.%), 0.1 Mt at Muluozhai (average grade = 3.97 wt.%), and 5764 t of REO at Lizhuang (average grade = 2.38 wt.%). Recent results from detailed geological surveys, and studies of petrographic features, ore-forming ages, ore forming conditions, and wallrock alteration are synthesized in this paper. REE mineralization within this belt is associated with carbonatite-syenite complexes, with syenites occurring as stocks intruded by carbonatitic sills or dikes. The mineralization is present as complex vein systems that contain veinlet, stringer, stockwork, and brecciated pipe type mineralization. Carbonatites in these carbonatite-related REE deposits (CARDs) are extremely rich in light REEs, Sr (>5000 ppm), and Ba (>1000 ppm), and have low Sr/Ba and high Ba/Th ratios, and radiogenic Sr-Nd isotopic compositions. These fertile magmas, which may lead to the formation of REE deposits, were generated by the partial melting of sub-continental lithospheric mantle (SCLM) that was metasomatized by REE- and CO2-rich fluids derived from subducted marine sediments. We suggest that this refertilization occurred along cratonic margins and, in particular, at a convergent margin where small-volume carbonatitic melts ascended along trans-lithospheric faults and transported REEs into the overlying crust, leading to the formation of the CARDs. The formation of fertile carbonatites requires a thick lithosphere and/or high pressures (>25 kbar), a metasomatized and enriched mantle source, and favorable pathways for magma to ascend into the overlying crust where REE-rich fluids exsolve from cooling magma. The optimal combination of these three factors only occurs along the margins of a craton with a continental root, rather than in modern subduction zones where the lithosphere is relatively thin.
DS201705-0858
2017
Moe, K., Yang, J-S., Johnson, P., Wang, W.Spectroscopic analysis of microdiamonds in ophiolitic chromitite and peridotite.Lithosphere, 9p.Asia, Tibet, Russia, UralsMicrodiamonds

Abstract: Microdiamonds ?200 ?m in size, occurring in ophiolitic chromitites and peridotites, have been reported in recent years. Owing to their unusual geological formation, there are several debates about their origin. We studied 30 microdiamonds from 3 sources: (1) chromitite ore in Luobusa, Tibet; (2) peridotite in Luobusa, Tibet; and (3) chromitite ore in Ray-Iz, polar Ural Mountains, Russia. They are translucent, yellow to greenish-yellow diamonds with a cubo-octahedral polycrystalline or single crystal with partial cubo-octahedral form. Infrared (IR) spectra revealed that these diamonds are type Ib (i.e., diamonds containing neutrally charged single substitutional nitrogen atoms, Ns0, known as the C center) with unknown broad bands observed in the one-phonon region. They contain fluid inclusions, such as water, carbonates, silicates, hydrocarbons, and solid CO2. We also identified additional microinclusions, such as chromite, magnetite, feldspar (albite), moissanite, hematite, and magnesiochromite, using a Raman microscope. Photoluminescence (PL) spectra measured at liquid nitrogen temperature suggest that these diamonds contain nitrogen-vacancy, nickel, and H2 center defects. We compare them with high-pressure-high-temperature (HPHT) synthetic industrial diamond grits. Although there are similarities between microdiamonds and HPHT synthetic diamonds, major differences in the IR, Raman, and PL spectra confirm that these microdiamonds are of natural origin. Spectral characteristics suggest that their geological formation is different but unique compared to that of natural gem-quality diamonds. Although these microdiamonds are not commercially important, they are geologically important in that they provide an understanding of a new diamond genesis.
DS201708-1705
2017
Liu, F.Ocean-continent transition to supersubduction zone origin of the western Yarlung Zangbo ophiolites in southwest Tibet, China: constraints from the petrology, mineralogy and geochemistry of the peridotites.11th. International Kimberlite Conference, PosterChina, Tibetsubduction

Abstract: The ophiolites that crop out discontinuously along the ?2000 km Yarlung Zangbo Suture zone (YZSZ) between the Nanga Parbat and Namche Barwa syntaxes in southern Tibet represent the remnants of Neotethyan oceanic lithosphere (Fig. 1a). We have investigated the internal structure and the geochemical makeup of mafic-ultramafic rock assemblages that are exposed in the westernmost segment of the YZSZ where the suture zone architecture displays two distinct sub-belts of ophiolitic and mélange units separated by a continental Zhongba terrane (Fig. 1b). These two sub-belts include the Daba – Xiugugabu in the south (Southern sub-belt, SSB) and the Dajiweng – Saga in the north (Northern sub-belt, NSB). We present new structural, geochemical, geochronological data from upper mantle peridotites and mafic dike intrusions occurring in these two sub-belts and discuss their tectonomagmatic origin. In-situ analysis of zircon grains obtained from mafic dikes within the Baer, Cuobuzha and Jianabeng massifs in the NSB, and within the Dongbo, Purang, Xiugugabu, Zhaga and Zhongba in the SSB have yielded crystallization ages ranging between130 and 122 Ma. Dike rocks in both sub-belts show N-MORB REE patterns and negative Nb, Ta and Ti anomalies, reminiscent of those documented from SSZ ophiolites. Harzburgitic host rocks of the mafic dike intrusions mainly display geochemical compositions of abyssal peridotites (Fig. 2), with the exception of the Dajiweng harzburgites, which show the geochemical signatures of forearc peridotites (Lian et al., 2016). Extrusive rocks that are spatially associated with these peridotite massifs in both sub-belts also have varying compositional and geochemical features. Tithonian to Valanginian (150 – 135 Ma) basaltic rocks in the Dongbo massif have OIB-like geochemistry and 138 Ma basaltic lavas in the Purang massif have EMORB-like geochemistry (Liu et al., 2015). Tuffaceous rocks in the Dajiweng massif are 140 Ma in age and show OIB-like geochemistry. We interpret these age and geochemical data to reflect a rifted continental margin origin of the extrusive rock units in both sub-belts. These data and structural observations show that the western Yarluang Zangbo ophiolites represent fragments of an Ocean-Continent Transition (OCT) peridotites altered by fluids in an initial supersubduction setting. We infer that mafic-ultramafic rock assemblages exposed in the SSB and NSB initially formed in an ocean – continent transition zone (OCTZ) during the late Jurassic, and that they were subsequently emplaced in the forearc setting of an intraoceanic subduction zone within a Neotethyan seaway during 130 to 122 Ma. The NSB and SSB are hence part of a single, S-directed nappe sheet derived from a Neotethyan seaway located north of the Zhongba terrane.
DS201805-0993
2018
Xiong, F., Yang, J., Xu, X., Kapsiotis, A., Hao, X., Liu, Z.Compositional and isotopic heterogeneities in the Neo-Tethyan upper mantle recorded by coexisting Al rich and Cr rich chromitites in the Purang massif, SW Tibet (China).Journal of Asian Earth Sciences, Vol. 159, pp. 109-129.China, Tibetchromitites

Abstract: The Purang harzburgite massif in SW Tibet (China) hosts abundant chrome ore deposits. Ores consist of 20 to >95% modal chromian spinel (Cr-spinel) with mylonitic fabric in imbricate shaped pods. The composition of Cr-spinel in these ores ranges from Al-rich [Cr#Sp or Cr/(Cr?+?Al)?×?100?=?47.60-57.56] to Cr-rich (Cr#Sp: 62.55-79.57). Bulk platinum-group element (PGE) contents of chromitites are also highly variable ranging from 17.5?ppb to ?2.5?ppm. Both metallurgical and refractory chromitites show a general enrichment in the IPGE (Os, Ir and Ru) with respect to the PPGE (Rh, Pt and Pd), resulting mostly in right-sloping primitive mantle (PM)-normalized PGE profiles. The platinum-group mineral (PGM) assemblages of both chromitite types are dominated by heterogeneously distributed, euhedral Os-bearing laurite inclusions in Cr-spinel. The Purang chromitites have quite inhomogeneous 187Os/188Os ratios (0.12289-0.13194) that are within the range of those reported for mantle-hosted chromitites from other peridotite massifs. Geochemical calculations demonstrate that the parental melts of high-Cr chromitites were boninitic, whereas those of high-Al chromitites had an arc-type tholeiitic affinity. Chromite crystallization was most likely stimulated by changes in magma compositions due to melt-peridotite interaction, leading to the establishment of a heterogeneous physicochemical environment during the early crystallization of the PGM. The highly variable PGE contents, inhomogeneous Os-isotopic compositions and varying Cr#Sp ratios of these chromitites imply a polygenetic origin for them from spatially distinct melt inputs. The generally low ?Os values (<1) of chromitites indicate that their parental melts originated within different sections of a heterogeneously depleted mantle source region. These melts were most likely produced in the mantle wedge above a downgoing lithospheric slab.
DS201807-1538
2015
Yang, J., Robinson, P.T., Dilek, Y.Diamond bearing ophiolites and their geological occurrence. ** note dateEpisodes, Vol. 38, 4, pp. 344-364.China, Tibet, Russiaophiolites

Abstract: We document in this study the geological occurrence of diamonds and other ultrahigh-pressure (UHP) minerals in ophiolitic mantle peridotites and podiform chromitites from different orogenic belts. These minerals exist in both high-Cr and high-Al chromitites. Most ophiolite-hosted diamonds are small (? 200-500 ?m across), and some contain distinctive inclusions (i.e., coesite, Ni-Mn-Co alloys, spessartite, tephroite). All of the analyzed diamonds have extremely light carbon isotope compositions (?13C = -28.7 to -18.3‰) and variable trace element contents that distinguish them from most kimberlitic and UHP metamorphic varieties. A wide range of highly reduced minerals, such as native elements, Ni-Mn-Co alloys, Fe-Si and Fe-C phases and moissanite (SiC) also occuras accompanying mineral separates confirming the super-reducing conditions of their environment of formation. The presence of exsolution lamellae of diopside and coesite in some chromite grains suggests chromite crystallization depths around >380 km, near the mantle transition zone. Carbon and other recycled crustal materials at these depths are likely to have been derived from previously subducted material. The peridotites encapsulating the podiform chromitites and diamonds were transported to shallow mantle by convection cells beneath oceanic spreading centers. The chromitites may have formed in the deep mantle or in shallow suprasubduction zone environments. Our observations suggest that diamonds, UHP minerals and recycled crustal material are likely to be ubiquitous in the oceanic mantle.
DS201812-2840
2018
Li, Y., Zhang, J., Mustofa, K.M.G., Wang, Y., Yu, S., Cai, Z., Li, P., Zhou, G., Fu, C., Mao, X.Petrogenesis of carbonatites in the Luliangshan region, North Qaidam, northern Tibet, China: evidence for recycling of sedimentary carbonate and mantle metasomatism within a subduction zone.Lithos, Vol. 322, pp. 148-165.China, Tibetcarbonatite

Abstract: Carbonatitic magmatism in subduction zones provides extremely valuable information on the cycling, behavior and storage of deep carbon within the Earth. It may also shed light on insights into crust-mantle interaction and mantle metasomatism within subduction zones. Origin of carbonatite has long been debated: all hypotheses need to reflect the different mineral assemblages and geochemical compositions of carbonatites and their diverse tectonic settings. Here we present a petrological, geochronological, geochemical and isotopic study of carbonatite bodies associated with orogenic peridotites, which occur as stocks or dykes with widths of tens to hundreds of meters in the Luliangshan region, North Qaidam, northern Tibet, China. On the basis of modal olivine (Ol) content, the studied samples were subdivided into two groups: Ol-poor carbonatite and Ol-rich carbonatite. Zircon grains from the Ol-poor carbonatite show detrital features, and yield a wide age spectrum between 400?Ma and 1000?Ma with a pronounced peak at ca. 410-430?Ma. By contrast, oscillatory zoned zircons and inherited cores show two relatively small Neoproterozoic age peaks at ca. 920 and 830?Ma. Zircon grains from the Ol-rich carbonatite sample are also distributed in a wide spectrum between 400 and 1000?Ma, with a pronounced peak at ca. 440?Ma and a slightly inferior peak at ca. 410?Ma. The oscillatory zoned zircons and inherited cores exhibit a smaller Neoproterozoic age peak at ca. 740?Ma. The pronounced peaks ranging from 430 to 410?Ma are consistent with the deep subduction and mantle metasomatic events recorded in associated ultramafic rocks. Both groups of carbonatites are characterized by enrichment of light rare earth elements (LREEs) with high (La/Yb)N values and pronounced negative Eu anomalies. They show high 87Sr/86Sr values (0.708156-0.709004), low 143Nd/144Nd values (0.511932-0.512013) and high ?18OV-SMOW values (+17.9 to +21.3‰). This geochemical and isotopic evidence suggests that these carbonatites were derived from remobilized sedimentary carbonate rocks. We propose that the primary carbonatite magma was formed by partial melting of sedimentary carbonates with mantle contributions. Sedimentary carbonates were subducted into the shallow upper mantle where they melted and formed diapirs that moved upwards through the hot mantle wedge. The case presented provides a rare example of carbonatite originating from sedimentary carbonates with mantle contributions and relevant information on the mantle metasomatism within a subduction zone.
DS201905-1080
2019
Tang, M., Lee, C-T.A., Rudnick, R.L., Condie, K.C.Rapid mantle convection drove massive crustal thickening in the late Archean. ( excluded kimberlites)Geochimica et Cosmochimica Acta, in press available, 32p.Asia, Tibet, Andesmelting

Abstract: The lithospheric mantle beneath Archean cratons is conspicuously refractory and thick compared to younger continental lithosphere (Jordan, 1988, Boyd, 1989; Lee and Chin, 2014), but how such thick lithospheres formed is unclear. Using a large global geochemical database of Archean igneous crustal rocks overlying these thick cratonic roots, we show from Gd/Yb- and MnO/FeOT-SiO2 trends that crustal differentiation required continuous garnet fractionation. Today, these signatures are only found where crust is anomalously thick (60-70?km), as in the Northern and Central Andes and Southern Tibet. The widespread garnet signature in Archean igneous suites suggests that thickening occurred not only in the lithospheric mantle but also in the crust during continent formation in the late Archean. Building thick crust requires tectonic thickening or magmatic inflation rates that can compete against gravitational collapse through lower crustal flow, which would have been enhanced in the Archean when geotherms were hotter and crustal rocks weaker. We propose that Archean crust and mantle lithosphere formed by thickening over mantle downwelling sites with minimum strain rates on the order of 10?13-10?12 s?1, requiring mantle flow rates associated with late Archean crust formation to be 10-100 times faster than today.
DS201906-1315
2019
Litasov, K.D., Kagi, H., Voropaev, S.A., Hirata, T., Ohfuji, H., Ishibashi., Makino, Y., Bekker, T.B., Sevastyanov, V.S., Afanasiev,V.P., Pokhilenko, N.P.Comparison of enigmatic diamonds from the Tolbachik arc volcano ( Kamchatka) and Tibetan ophiolites: assessing the role of contamination by synthetic materials. Gondwana Research, in press available 38p.Russia, Asia, Tibetdeposit - Tolbachik

Abstract: The enigmatic appearance of cuboctahedral diamonds in ophiolitic and arc volcanic rocks with morphology and infrared characteristics similar to synthetic diamonds that were grown from metal solvent requires a critical reappraisal. We have studied 15 diamond crystals and fragments from Tolbachik volcano lava flows, using Fourier transform infrared spectrometry (FTIR), transmission electron microscopy (TEM), synchrotron X-ray fluorescence (SRXRF) and laser ablation inductively coupled plasma mass-spectrometry (LA-ICP-MS). FTIR spectra of Tolbachik diamonds correspond to typical type Ib patterns of synthetic diamonds. In TEM films prepared using focused ion beam technique, we find Mn-Ni and Mn-Si inclusions in Tolbachik diamonds. SRXRF spectra indicate the presence of Fe-Ni and Fe-Ni-Mn inclusions with Cr, Ti, Cu, and Zn impurities. LA-ICP-MS data show variable but significantly elevated concentrations of Mn, Fe, Ni, and Cu reaching up to 70?ppm. These transition metal concentration levels are comparable with those determined by LA-ICP-MS for similar diamonds from Tibetan ophiolites. Mn-Ni (+Fe) solvent was widely used to produce industrial synthetic diamonds in the former USSR and Russia with very similar proportions of these metals. Hence, it appears highly probable that the cuboctahedral diamonds recovered from Kamchatka arc volcanic rocks represent contamination and are likely derived from drilling tools or other hard instruments. Kinetic data on diamond dissolution in basaltic magma or in fluid phase demonstrate that diamond does not form under the pressures and temperature conditions prevalent within the magmatic system beneath the modern-day Klyuchevskoy group of arc volcanoes. We also considered reference data for inclusions in ophiolitic diamonds and compared them with the composition of solvent used in industrial diamond synthesis in China. The similar inclusion chemistry close to Ni70Mn25Co5 for ophiolitic and synthetic Chinese diamonds scrutinized here suggests that most diamonds recovered from Tibetan and other ophiolites are not natural but instead have a synthetic origin. In order to mitigate further dubious reports of diamonds from unconventional tectonic settings and source rocks, we propose a set of discrimination criteria to better distinguish natural cuboctahedral diamonds from those produced synthetically in industrial environments and found as contaminants in mantle- and crust-derived rocks.
DS202007-1159
2020
Li, W, Yang, Z., Chiaradia, M., Yong, L., Caho, Yu., Zhang, J.Redox state of southern Tibetan mantle and ultrapotassic magmas. Lhasa TerraneGeology, Vol. 48, 7, pp. 733-736. pdfAsia, Tibetalkaline rocks

Abstract: The redox state of Earth’s upper mantle in several tectonic settings, such as cratonic mantle, oceanic mantle, and mantle wedges beneath magmatic arcs, has been well documented. In contrast, oxygen fugacity (graphic) data of upper mantle under orogens worldwide are rare, and the mechanism responsible for the mantle graphic condition under orogens is not well constrained. In this study, we investigated the graphic of mantle xenoliths derived from the southern Tibetan lithospheric mantle beneath the Himalayan orogen, and that of postcollisional ultrapotassic volcanic rocks hosting the xenoliths. The graphic of mantle xenoliths ranges from ?FMQ = +0.5 to +1.2 (where ?FMQ is the deviation of log graphic from the fayalite-magnetite-quartz buffer), indicating that the southern Tibetan lithospheric mantle is more oxidized than cratonic and oceanic mantle, and it falls within the typical range of mantle wedge graphic values. Mineralogical evidence suggests that water-rich fluids and sediment melts liberated from both the subducting Neo-Tethyan oceanic slab and perhaps the Indian continental plate could have oxidized the southern Tibetan lithospheric mantle. The graphic conditions of ultrapotassic magmas show a shift toward more oxidized conditions during ascent (from ?FMQ = +0.8 to +3.0). Crustal evolution processes (e.g., fractionation) could influence magmatic graphic, and thus the redox state of mantle-derived magma may not simply represent its mantle source.
DS202101-0044
2021
Zhang, M., Wang, C., Zhang, Qi., Qin, Y., Shen, J., Hu, X., Zhou, G., Li, S.Temporal-spatial analysis of alkaline rocks based in GEOROC. Not specific to diamondsApplied Geochemistry, Vol. 124, 104853 8p. PdfAsia, TibetGEOROC
DS202102-0226
2021
Tang, M., Ji, W-Q., Chu, X., Wu, A., Chen, C.Reconstructing crustal thickness evolution from europium anomalies in detrital zircons.Geology, Vol. 49, pp. 76-80. pdfAsia, Tibetzircons

Abstract: A new data compilation shows that in intermediate to felsic rocks, zircon Eu/Eu* [chondrite normalized Eu/ graphic] correlates with whole rock La/Yb, which has been be used to infer crustal thickness. The resultant positive correlation between zircon Eu/Eu* and crustal thickness can be explained by two processes favored during high-pressure differentiation: (1) supression of plagioclase and (2) endogenic oxidation of Eu2+ due to garnet fractionation. Here we calibrate a crustal thickness proxy based on Eu anomalies in zircons. The Eu/Eu*-in-zircon proxy makes it possible to reconstruct crustal thickness evolution in magmatic arcs and orogens using detrital zircons. To evaluate this new proxy, we analyzed detrital zircons separated from modern river sands in the Gangdese belt, southern Tibet. Our results reveal two episodes of crustal thickening (to 60-70 km) since the Cretaceous. The first thickening event occurred at 90-70 Ma, and the second at 50-30 Ma following Eurasia-India collision. These findings are temporally consistent with contractional deformation of sedimentary strata in southern Tibet.
 
 

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