Jump to ContentJump to Main Navigation
Show Summary Details
More options …

American Mineralogist

Journal of Earth and Planetary Materials

Ed. by Baker, Don / Xu, Hongwu / Swainson, Ian

IMPACT FACTOR 2018: 2.631

CiteScore 2018: 2.55

SCImago Journal Rank (SJR) 2018: 1.355
Source Normalized Impact per Paper (SNIP) 2018: 1.103

See all formats and pricing
More options …
Volume 101, Issue 6


Discovery of in situ super-reducing, ultrahigh-pressure phases in the Luobusa ophiolitic chromitites, Tibet: new insights into the deep upper mantle and mantle transition zone

Ru Y. Zhang
  • Corresponding author
  • CARMA, State Key Laboratory of Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing, 100037, China
  • Department of Geosciences, National Taiwan University, Taipei 106, Taiwan, ROC
  • Department of Geological Science, Stanford University, Stanford, California 94305-2115, U.S.A
  • Email
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Jing-Sui Yang / W.G. Ernst / Bor-Ming Jahn / Yoshiyuki Iizuka / Guo-Lin Guo
  • CARMA, State Key Laboratory of Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing, 100037, China
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
Published Online: 2016-06-03 | DOI: https://doi.org/10.2138/am-2016-5436


Previous research on super-reducing ultrahigh-pressure (SuR UHP) phases from the Tibetan ophiolitic chromitites were mainly conducted on isolated grains extracted from extremely large samples. This approach has been questioned because of possible contamination. To elucidate the occurrence and origin of these SuR UHP minerals, we studied 33 thin sections and rock chips of three ophiolitic chromitites from the Yarlung Zangbo suture zone. Here we report and analyze unambiguously in situ SuR UHP assemblages from the ophiolitic chromitites by electron probe micro-analyzer, scanning microscope and Laser Raman spectroscope. The SuR UHP and associated phases include: (1) blue moissanite as inclusions in olivine (Fo96–98), and in olivine domains between disseminated chromite grains; (2) multiple inclusions of moissanite + wüstite + native Fe in olivine; (3) FeNi and FeCr alloys in olivine and chromite; and (4) native Fe and Si in chromite. Crustal asphaltum and h-BN also occur as inclusions in chromite. Our documented in situ SuR UHP phases, combined with the previously inferred existence of ringwoodite + stishovite, all indicate that these assemblages formed under a highly reducing environment (oxygen fugacities several orders of magnitude lower than that of the iron-wüstite buffer) in the mantle transition zone (MTZ) and in the deep upper mantle. Diamond + moissanite with distinct 13C-depleted compositions from chromitites have a metasedimentary carbon source. Associations with existing crustal minerals in chromitites demonstrate that carbon-bearing metasedimentary rocks were recycled into the mantle through subduction, and locally modified its composition. Finally we propose a three-stage model to explain the formation of SuR UHP phase-bearing chromitite. Discoveries of SuR UHP phases in Luobusa and other ophiolitic podiform chromitites from the polar Ural Mountains and from Myanmar imply existence of a new type of ophiolitic chromitite. Such occurrences provide an additional window to explore the physical-chemical conditions of the MTZ, mantle dynamics, and the profound recycling of crustal materials.

Key words: Ophiolitic chromitite; in situ; super-reducing UHP phases; deep upper mantle; mantle transition zone; Tibet; moissanite; wüstite; Invited Centennial article

References Cited

  • Arai, S. (2013) Conversion of low-pressure chromitites to ultrahigh-pressure chromitites by deep recycling: A good inference. Earth and Planetary Science Letters, 379, 81–87.Google Scholar

  • Bai, W.J., Zhou, M.F., and Robinson, P.T. (1993) Possible diamond-bearing mantle peridotites and chromitites in the Luobusa and Dongiao ophiolites, Tibet. Canadian Journal of Earth Sciences, 30, 1650–1659.Google Scholar

  • Bai, W.J., Robinson, P.T., Fang, Q.S., Yang, J.S., Yan, B., Zhang, Z., Hu, X.-F. Zhou, M.-F., and Malpas, J. (2000) The PGE and base-metal alloys in the podiform chromitites of the Luobusha ophiolite, southern Tibet. Canadian Mineralogist, 38, 585–598.Google Scholar

  • Bai, W.J., Yang, J.S., Fang, Q.S., Yan, B.G., and Shi, R.D. (2003) An unusual mantle mineral group in ophiolites of Tibet. Chinese Geology, 30, 144–150 (in Chinese with English abstract).Google Scholar

  • Ballhaus, C. (1995) Is the upper mantle metal-saturated? Earth and Planetary Science Letters, 132, 75–86.Google Scholar

  • Birch, F. (1952) Elastical and constitution of the Earth’s interior. Journal of Geophysics Research, 57, 227–286.Google Scholar

  • Cartigny, P. (2005) Stable isotopes and the origin of diamond. Elements, 1, 79–84.Google Scholar

  • Cartigny, P. (2009) Volatile composition of microinclusions in diamonds from the Panda kimberlite, Canada: Implications for chemical and isotopic heterogeneity in the mantle. Geochimica et Cosmochimca Acta, 73, 1779–1794.Google Scholar

  • Coleman, R.G. (1977) Ophiolites-Ancient Oceanic Lithosphere? Springer-Verlag, Berlin.Google Scholar

  • Dilek, Y., and Furnes, H. (2014) Ophiolites and their origins. Elements, 10, 2–9.Google Scholar

  • Dobrzhinetskaya, L.F., and Green, H.W. (2007) Diamond synthesis from graphite in the presence of water and SiO2: Implications fro diamond formation in quartzites from Kazakhstan. International Geology Review, 49, 389–400.Google Scholar

  • Dobrzhinetskaya, L.F., Wirth, R., Yang, Y.J., Hutcheon, I.D., Weber, P.K., and Green, H.W. (2009) High-pressure highly reduced nitrides and oxides from chromitite of a Tibetan ophiolite. Proceedings of the National Academy of Sciences, 106, 19233–19238.Google Scholar

  • Dobrzhinetskaya, L.F., Wirth, R., Yang, Y.J., Green, H.W., Hutcheon, I.D., Weber, P.K., and Grew, E.S. (2014) Qingsongite, natural cubic boron nitride: the first boron mineral from the Earth’s mantle. American Mineralogist, 99, 764–772.Google Scholar

  • Essene, E.J., and Fisher, D.C. (1986) Lightning strike fusion: extreme reduction and metalsilicate liquid immiscibility. Science 234, 189–193.Google Scholar

  • Frost, D.J., and McCammon, C.A. (2008) The Redoc state of Earth’s mantle. Annual Review of Earth Planet Sciences, 36, 389–420.Google Scholar

  • Frost, D.J., Liebske, C., Langenhorst, F., McCammon, C.A., Trønnes, R., and Rubie, D.C. (2004) Experimental evidence for the existence of iron-rich metal in the Earth’s lower mantle. Nature, 428, 409–411.Google Scholar

  • Fukao, Y., Widiyantoro, S., and Obayashi, M. (2001) Stagnant slabs in the upper and lower mantle transition region. Reviews of Geophysics, 39, 291–323.Google Scholar

  • Haggerty, S.E., and Sautter, V. (1990) Ultradeep (greater than 300 kilometers), ultramafic upper mantle xenoliths. Science, 248, 993–996.Google Scholar

  • Hazen, R.M., Downs, R.T., Jones, A.P., and Kah, L. (2013) Carbon mineralogy and crystal chemistry. Reviews of Mineralogy and Geochemistry, 75, 7–46.Google Scholar

  • Hirsch, L.M. (1991) The Fe-FeO buffer at low mantle pressures and temperatures. Geophysical Research Letters, 18, 1309–1312.Google Scholar

  • Ishii, T., Kojitani, H., Fujino, K., Yusa, H., Mori, D., Inaguma, Y., Matsushita, Y., Yamaura, K., and Akaogi, M. (2015) High-pressure high-temperature transitions in MgCr2O4 and crystal structures of new MgCr2O5 and post-spinel MgCr2O4 phases with implications for ultrahigh-pressure chromitites in ophiolites. American Mineralogist, 100, 59–65.Google Scholar

  • Lauterbach, S., McCammon, C.A., Aken, P. van., Langenhorst, F., and Seifert, F. (2000) Mössbauer and ELNES spectroscopy of (Mg,Fe)(Si,Al)O3 prerovskite: A highly oxidized component of the lower mantle. Contributions to Mineralogy and Petrology, 138, 17–26.Google Scholar

  • Liou, J.G., Tsujimori, T., Yang, J.S., Zhang, R.Y., and Ernst, W.G. (2014) Recycling of crustal material through study of ultrahigh-pressure minerals in collisional orogens, ophiolites, and mantle xenoliths: A review. Journal of Asian Earth Sciences, 96, 386–420.Google Scholar

  • Malpas, J., Zhou, M.F., Robinson, P.T., and Reynolds, P.H. (2003) Geochemical and geochronological constraints on the origin and emplacement of the Yarlung-Zangbo ophiolites, southern Tibet. Geological Society, London, Special Publications, 218, 191–206.Google Scholar

  • Mathez, R.A., Fogel, E.A., Hutcheon, I.D., and Marshintsev, V.K. (1995) Carbon isotope composition and origin of SiC from kimberlites of Yakutia, Russia. Geochimica et Cosmochimica Acta, 59, 781–791.Google Scholar

  • McCammon, C.A. (2005) Mantle Oxidation State and Oxygen Fugacity: Constraints on mantle chemistry, structure, and Dynamics. Earth’s deep mantle: structure, composition, and evolution. Geophysical Monograph Series, 160, 219–240.Google Scholar

  • McDonough, W.F., and Sun, S.S. (1995) The composition of the Earth. Chemical Geology, 120, 223–253.Google Scholar

  • McGowan, N.M., Griffin, W.L., González-Jiménez, J.M., Belousova, E., Afonso, J.C., Shi, R., McCammon, C.A., Pearson, N.J., and O’Reilly, S.Y. (2015) Tibetan chromitites: Excavating the slab graveyard. Geology, 43, 179–182.Google Scholar

  • Quintiliani, M., Andreozzi, G.B., and Graziani, G. (2006) Fe2+ and Fe3+ quantification by different approaches and fO2 estimation for Albanian Cr-spinel. American Mineralogist, 91, 907–916.Google Scholar

  • Robinson, P.T., Bai, W.J., Malpas, J., Yang, J.S., Zhou, M.F., Fang, Q.S., Hu, X.F., Cameron, S., and Staudigel, H. (2004) Ultra-high pressure minerals in the Luobusa ophiolite, Tibet, and their tectonic implications. Geological Society, London, Special Publications, 226, 247–271.Google Scholar

  • Robinson, P.T., Trumbull, R.B., Schmitt, A., Yang, J.S., Li, J.W., Zhou, M-F., Erzinger, J., Dare, S., and Xiong, F-H. (2015) The origin and significance of crustal minerals in ophiolitic chromitites and peridotites. Gondwana Research, 27, 487–506.Google Scholar

  • Ruskov, T., Spirov, I., Georgieva, M., Yamamoto, S., Green, H.W., McCammon, C.A., and Dobrzhinetskaya, L.F. (2010) Mossbauer spectroscopy studies of the valence state of iron in chromite from the Luobusa massif of Tibet: implications for a highly reduced deep mantle. Journal of Metamorphic Geology, 28, 551–560.Google Scholar

  • Schmidt, M.W., Gao, C., Golubkova, A., Rohrbach, A., and Connolly, J.A.D. (2014) Natural moissanite (SiC)—a low temperature mineral formed from highly fractionated ultra-reducing COH-fluids. Progress in Earth and Planetary Science, 127, 279–307.Google Scholar

  • Shiryaev, A.A., Griffin, W.L., and Stoyanov, E. (2011) Moissanite (SiC) from kimberlites: polytypes, trace elements, inclusions and speculation on origin. Lithos, 122, 152–164.Google Scholar

  • Sobolev, N.V., and Shatsky, V.S. (1990) Diamond inclusions in garnets from metamorphic rocks: a new environment for diamond formation. Nature, 343, 742–746.Google Scholar

  • Stachel, T., Brey, G.P., and Harris, J.W. (2000) Kankan diamonds (Guinea) I: from the lithosphere down to the transition zone. Contributions to Petrology and Mineralogy, 140, 1–15.Google Scholar

  • Stachel, T., Brey, G.P., and Harris, J.W. (2005) Inclusions in sublithospheric diamonds: Glimpses of deep Earth. Elements, 1, 73–78.Google Scholar

  • Trumbull, R.B., Yang, J.S., Robinson, P.T., Di Pierro, S., Vennemann, T., and Wiedenbeck, M. (2009) The carbon isotope composition of natural SiC (moissanite) from the Earth’s mantle: New discoveries from ophiolites. Lithos, 113, 612–620.Google Scholar

  • Ulmer, G., Grandstaff, D.E., Woermann, E., Göbbels, M., Schönitz, M., and Woodland, A.B. (1998) The redox stability of moissanite (SiC) compared with metal-metal oxide buffers at 1773 K and at pressures up to 90 kbar. Neues Jahrbuch für Mineralogie-Abhandlungen, 172, 279–307.Google Scholar

  • Walter, M.J., Kohn, S.C., Araujo, D., Bulanova, G.P., Smith, C.B., Gillou, E., Wang, J., Steele, A., and Shirey, S.B. (2011) Deep mantle cycling of oceanic crust: evidence from diamonds and their mineral inclusions. Science, 334, 54–57.Google Scholar

  • Whitney, D.L., and Evans, B. (2010) Abbreviations for names of rock-forming minerals. American Mineralogist, 95, 185–187.Google Scholar

  • Wirth, R., Kamincky, F., Matsuk, S., and Schreiber, A. (2009) Unusual micro- and nano-inclusions in diamond from the Juina area, Brazil. Earth and Planetary Science Letters, 286, 292–303.Google Scholar

  • Woermann, E., and Rosenhauer, M. (1985) Fluid phases and the redox state of the Earth’s mantle: Extrapolation based on experimental, phase-theoretical and petrological data. Fortschritte der Mineralogie, 63, 263–349.Google Scholar

  • Woodland, A.B., and Koch, M. (2003) Variation in oxygen fugacity with depth in the upper mantle beneath the Kaapvaal craton, Southern Africa. Earth and Planetary Science Letters, 214, 295–310.Google Scholar

  • Xiong, F.H., Yang, J.S., Robinson, P.T., Xu, X.Z., Liu, Z., Li, Y., Li, J.Y., and Chen, S.Y. (2015) Origin of podiform chromitite, a new model based on the Luobusa ophiolite, Tibet. Gondwana Research, 27, 525–542.Google Scholar

  • Xu, X.Z., Yang, J.S., Chen, S.Y., Fang, Q.S., Bai, W.J., and Ba, D.Z. (2009) Unusual mantle mineral group from chromitite ore body Cr-11 in Luobusa ophiolite of the Yarlung-Zangbo suture zone, Tibet. Journal of Earth Sciences, 20, 284–302.Google Scholar

  • Xu, X.Z., Yang, J.S., Robinson, P.T., Xiong, F.H., Ba, D.Z., and Guo, G.L. (2015) Origin of ultrahigh pressure and highly reduced minerals in podiform chromitites and associated mantle peridotites of the Luobusa ophiolite, Tibet. Gondwana Research, 27, 507–524.Google Scholar

  • Yamamoto, S., Komiya, T., Hirose, H., and Maruyama, S. (2009) Coesite and clinopyroxene exsolution lamellae in chromites: In-situ ultrahigh-pressure evidence from podiform chromitites in the Luobusa ophiolite, southern Tibet. Lithos, 109, 314–322.Google Scholar

  • Yamamoto, S., Komiya, T., Yamamoto, H., Kaneko, Y., Terabayashi, M., Katayama, I., Iizuka, T., Maruyama, S., Yang, J.S., Kon, Y., and Hirata, T. (2013) Recycled crustal zircons from podiform chromitites in the Luobusa ophiolite, southern Tibet. The Island Arc, 22, 89–103.Google Scholar

  • Yang, J.S., Dobrzhinetskaya, L., Bai, W.J., Fang, Q.S., Robinson, P.T., Zhang, J.F., and Green, H.W. II (2007) Diamond- and coesite-bearing chromitites from the Luobusa ophiolite, Tibet. Geology, 35, 875–878.Google Scholar

  • Yang, J.S., Robinson, P.T., and Dilek, I. (2014) Diamonds in ophiolite. Element, 10, 127–130.Google Scholar

  • Yang, J.S., Meng, F.C., Xu, X.Z., Robinson, P.T., Dilek, Y., Makeyev, A.B., Wirth, R., Wiedenbeck, M., Griffin, W.L., and Cliff, J. (2015) Diamonds, native elements and metal alloys from chromitites of the Ray-Iz ophiolite of the Polar Urals. Gondwana Research, 27, 459–485.Google Scholar

  • Zhang, R.Y., Liou, J.G., Ernst, W.G., Coleman, R.G., Sobolev, N.V., and Shatsky, V.S. (1997) Metamorphic evolution of diamond-bearing and associated rocks from the Kokchetav Massif, northern Kazakhstan. Journal of Metamorphic Geology, 15, 479–496.Google Scholar

  • Zhang, R.Y., Liou, J.G., Omori, S., Sobolev, N.V., Shatsky, V.S., Iizuka, Y., Lo, C-H., and Ogasawara, Y. (2012) Tale of the Kulet eclogite from the Kokchetav Massive, Kazakhstan: Initial tectonic setting and transition from amphibolite to eclogite. Journal of Metamorphic Geology, 30, 537–559.Google Scholar

  • Zhong, L.F., Xia, B., Zhang, Y.Q., Wang, R., Wei, D.L., and Yang, Z.Q. (2006) SHRIMP age determination of the diabase in Luobusha ophiolite, southern Xizang (Tibet). Geological Review, 52, 224–229 (in Chinese with English abstract).Google Scholar

  • Zhou, M.F., Robinson, P.T., Malpas, J., and Li, Z. (1996) Podiform chromitites in the Luobusa ophiolite (southern Tibet): Implications for melt-rock interaction and chromite segregation in the upper mantle. Journal of Petrology, 37, 3–21.Google Scholar

  • Zhou, M.F., Robinson, P.T., Malpas, J., Edwards, S.J., and Qi, L. (2005) REE and PGE geochemical constraints on the formation of dunites in the Luobusa ophiolite, southern Tibet. Journal of Petrology, 46, 615–639.Google Scholar

  • Zhou, M.F., Robinson, P.T., Su, B-X., Gao, J., Li, W., Yang, J-S., and Malpas, J. (2014) Compositions of chromite, associated minerals, and parental magmas of podiform chromite deposits: The role of slab contamination of asthenospheric melts in suprasubduction zone environments. Gondwana Research, 26, 262–283.Google Scholar

About the article

Received: 2015-05-24

Accepted: 2016-01-22

Published Online: 2016-06-03

Published in Print: 2016-06-01

Citation Information: American Mineralogist, Volume 101, Issue 6, Pages 1245–1251, ISSN (Online) 1945-3027, ISSN (Print) 0003-004X, DOI: https://doi.org/10.2138/am-2016-5436.

Export Citation

© 2016 by Walter de Gruyter Berlin/Boston.

Comments (0)

Please log in or register to comment.
Log in