Origin of Chromitites in the Songshugou Peridotite Massif, Qinling Orogen (Central China): Mineralogical and Geochemical Evidence

Abstract

The Songshugou peridotite massif is located in the north of Shangdan suture zone, North Qinling orogenic belt of Central China. The massif is mainly composed of fine-grained mylonitic dunites, coarse-grained dunites, fine- and coarse-grained harzburgites, and minor clinopyroxenites. The coarsegrained dunites as well as parts of the harzburgites host small-scale chromitites. Chromite grains from various textural types of chromitites and dunites pervasively contain primary and secondary silicate inclusions. Primary inclusions are dominated by monophase olivine, with minor clinopyroxene and a few multiphase mineral assemblages consisting of olivine and clinopyroxene. Secondary inclusions, mainly Cr-chlorite and tremolite, show irregular crystal shapes. Besides, Cr₂O₃ contents (0.08 wt.%–0.71 wt.%) of primary olivine inclusions are remarkably higher than those of interstitial olivine (<0.1 wt.%). Chromites in the Songshugou peridotite massif are high-Cr type, with Cr^# and Mg^# values ranging of 67.5–87.6, and 23.4–41.2, respectively. The Cr-chlorite, formed by reactions between olivine and chromite in the presence of fluid under middle temperature, indicates the Songshugou peridotite massif has undergone alteration/metamorphism process during emplacement. Chromite grains are modified by these processes, resulting in the various degrees of enrichment of Fe₂O₃, Cr₂O₃, Zn, Co and Mn, depletion of MgO, Al₂O₃, Ga, Ti and Ni. Due to low silicate/chromite ratios in the massive ores, chromites from them are slightly influenced by alteration/metamorphism and thus preserve the pristine magmatic compositions. The parental magma calculated based on them has 11.17 wt.%–13.57 wt.% A1₂O₃ and 0.15 wt.%–0.27 wt.% TiO₂, which is similar to the parental melts of high-Cr chromitites from elsewhere and comparable with those of boninites. Combined with informations from previous studies, major and trace elements geochemistry of chromite, as well as the nature of the parental magma, it can be revealed that the Songshugou chromitities formed in a supra-subduction zone environment.

Keywords

peridotite / chromitite / chromite trace element / parental magma / Songshugou / Qinling Orogen

References

Akbulut M, González-Jiménez J M, Griffin W L, . Tracing Ancient Events in the Lithospheric Mantle: A Case Study from Ophiolitic Chromitites of SW Turkey. Journal of Asian Earth Sciences, 2016, 119: 1-19.

Arai S, Matsukage K. Petrology of a Chromitite Micropod from Hess Deep, Equatorial Pacific: A Comparison between Abyssal and Alpine-Type Podiform Chromitites. Lithos, 1998, 43(1): 1-14.

Ballhaus C, Wirth R, Fonseca R O C, . Ultra-High Pressure and Ultra-Reduced Minerals in Ophiolites may Form by Lightning Strikes. Geochemical Perspectives Letters, 2017, 5: 42-46.

Barnes S J. Chromite in Komatiites, II. Modification during Green-schist to Mid-Amphibolite Facies Metamorphism. Journal of Petrology, 2000, 41(3): 387-409.

Barnes S J, Roeder P L. The Range of Spinel Compositions in Terrestrial Mafic and Ultramafic Rocks. Journal of Petrology, 2001, 42(12): 2279-2302.

Bonatti E, Michael P J. Mantle Peridotites from Continental Rifts to Ocean Basins to Subduction Zones. Earth and Planetary Science Letters, 1989, 91(3/4): 297-311.

Burkhard D J M. Accessory Chromium Spinels: Their Coexistence and Alteration in Serpentinites. Geochimica et Cosmochimica Acta, 1993, 57(6): 1297-1306.

Cao Y, Song S G, Su L, . Highly Refractory Peridotites in Songshugou, Qinling Orogen: Insights into Partial Melting and Melt/Fluid-Rock Reactions in Forearc Mantle. Lithos, 2016, 234-254.

Cao Y, Jung H, Song S G. Olivine Fabrics and Tectonic Evolution of Fore-Arc Mantles: A Natural Perspective from the Songshugou Dunite and Harzburgite in the Qinling Orogenic Belt, Central China. Geochemistry, Geophysics, Geosystems, 2017, 18(3): 907-934.

Cathelineau M, Nieva D. A Chlorite Solid Solution Geothermometer. The Los Azufres (Mexico) Geothermal System. Contributions to Mineralogy and Petrology, 1985, 91(3): 235-244.

Cathelineau M. Cation Site Occupancy in Chlorites and Illites as a Function of Temperature. Clay Minerals, 1988, 23(4): 471-485.

Chen D L, Ren Y F, Gong X K, . Identification and Its Geological Significance of Eclogite in Songshugou, the North Qinling. Acta Petrologica Sinica, 2015, 31(7): 1841-1854.

Colas V, González-Jiménez J M, Griffin W L, . Fingerprints of Metamorphism in Chromite: New Insights from Minor and Trace Elements. Chemical Geology, 2014, 389: 137-152.

Dong Y P, Santosh M. Tectonic Architecture and Multiple Orogeny of the Qinling Orogenic Belt, Central China. Gondwana Research, 2016, 29(1): 1-40.

Dong Y P, Zhang G W, Neubauer F, . Tectonic Evolution of the Qinling Orogen, China: Review and Synthesis. Journal of Asian Earth Sciences, 2011, 41(3): 213-237.

Dong Y P, Zhou M F, Zhang G W, . The Grenvillian Songshugou Ophiolite in the Qinling Mountains, Central China: Implications for the Tectonic Evolution of the Qinling Orogenic Belt. Journal of Asian Earth Sciences, 2008, 32(5/6): 325-335.

Evans B W, Hattori K, Baronnet A. Serpentinite: What, Why, Where?. Elements, 2013, 9(2): 99-106.

Gervilla F, Padrón-Navarta J A, Kerestedjian T, . Formation of Ferrian Chromite in Podiform Chromitites from the Golyamo Kamenyane Serpentinite, Eastern Rhodopes, SE Bulgaria: A Two-Stage Process. Contributions to Mineralogy and Petrology, 2012, 164(4): 643-657.

González-Jiménez J M, Locmelis M, Belousova E, . Genesis and Tectonic Implications of Podiform Chromitites in the Metamorphosed Ultramafic Massif of Dobromirtsi (Bulgaria). Gondwana Research, 2015, 27(2): 555-574.

González-Jiménez J M, Griffin W L, Proenza J A, . Chromitites in Ophiolites: How, Where, When, Why? Part II. The Crystallization of Chromitites. Lithos, 2014, 189: 140-158.

González-Jiménez J M, Barra F, Garrido L N F, . A Secondary Precious and Base Metal Mineralization in Chromitites Linked to the Development of a Paleozoic Accretionary Complex in Central Chile. Ore Geology Reviews, 2016, 78: 14-40.

González-Jiménez J M, Camprubi A, Colás V, . The Recycling of Chromitites in Ophiolites from Southwestern North America. Lithos, 2017, 53-72.

Graham I T, Franklin B J, Marshall B. Chemistry and Mineralogy of Podiform Chromitite Deposits, Southern NSW, Australia: A Guide to Their Origin and Evolution. Mineralogy and Petrology, 1996, 57(3/4): 129-150.

Griffin W L, Afonso J C, Belousova E A, . Mantle Recycling: Transition Zone Metamorphism of Tibetan Ophiolitic Peridotites and Its Tectonic Implications. Journal of Petrology, 2016, 57(4): 655-684.

Guo G L, Yang J S, Liu X D, . Mid-Ocean Ridge (MOR) and Suprasubduction Zone (SSZ) Geological Events in the Yarlung Zangbo Suture Zone: Evidence from the Mineral Record of Mantle Peridotites. Journal of Asian Earth Sciences, 2015, 110: 33-54.

Hey M H. ANew Review of the Chlorites. Mineralogical Magazine and Journal of the Mineralogical Society, 1954, 30(224): 277-292.

Irvine T N. Chromian Spinel as a Petrogenetic Indictor: Part 2. Petrologic Applications. Canadian Journal of Earth Sciences, 1967, 4(1): 71-103.

Jollands M C O H S C V O J, . Substitution and Diffusion of Cr²⁺ and Cr³⁺ in Synthetic Forsterite and Natural Olivine at 1 200–1 500 °C and 1 bar. Geochimica et Cosmochimica Acta, 2018, 220: 407-428.

Kamenetsky V S, Crawford A J, Meffre S. Factors Controlling Chemistry of Magmatic Spinel: An Empirical Study of Associated Olivine, Cr-Spinel and Melt Inclusions from Primitive Rocks. Journal of Petrology, 2001, 42(4): 655-671.

Kelemen P B, Hirth G, Shimizu N, . A Review of Melt Migration Processes in the Adiabatically Upwelling Mantle beneath Oceanic Spreading Ridges. Philosophical Transactions of the Royal Society of London Series A: Mathematical, Physical and Engineering Sciences, 1997, 355(1723): 283-318.

Klein E L, Koppe J C. Chlorite Geothermometry and Physicochemical Conditions of Gold Mineralization in the Paleoproterozoic Caixas Deposit, São Luis Craton, Northern Brazil. Geochimica Brasiliensis, 2000, 14(2): 219-232.

Kranidiotis P, MacLean W H. Systematics of Chlorite Alteration at the Phelps Dodge Massive Sulfide Deposit, Matagami, Quebec. Economic Geology, 1987, 82(7): 1898-1911.

Lee B, Zhu L M, Gong H J, . Genetic Relationship between Peridotites and Chromite Deposit from Songshugou Area of North Qinling. Acta Petrologica Sinica, 2010, 26: 1487-1502.

Li H Y, Liu J F, Yang L. Characteristics of Zircons from a Meta-morphic Contact Zone of the Songshugou Ultramafic Pluton in North Qinling and Their Geological Significance. Acta Petrologica Sinica, 2009, 28: 225-234.

Lian D, Yang J, Yildirim D, . Deep Mantle Origin and Ultra-Reducing Conditions in Podiform Chromitite: Diamond, Moissanite, and other Unusual Minerals in Podiform Chromitites from the Pozanti-Karsanti Ophiolite, Southern Turkey. American Mineralogist, 2017, 102(5): 1101-1113.

Liang F H, Yang J S, Xu Z Q, . Chromium in the Olivine Lattice: Chromium-Rich Olivines and Their Implication of Deep Mantle Origin in the Luobusa Mantle Peridotite and Chromitite, Tibet. Acta Petrologica Sinica, 2014, 30(8): 2125-2136.

Liu J F, Li C, Sun Y, . Melt Percolation in the Songshugou Ultramafic Massif of the Qinling Orogenic Belt, Central China. International Geology Review, 2014, 57(9/10): 1326-1339.

Liu J F, Sun Y, Tong L X, . Emplacement Age of the Songshugou Ultramafic Massif in the Qinling Orogenic Belt, and Geologic Implications. International Geology Review, 2009, 51(1): 58-76.

Liu J G, Hattori K, Wang J. Mineral Inclusions in Chromite from the Chromite Deposit in the Kudi Ophiolite, Tibet, Proto-Tethys. Acta Geologica Sinica, 2017, 91(2): 469-485.

Liu L, Zhou D W, Dong Y P, . High Pressure Metabasites and Their Retrograde Metamorphic P-T-t Path from Songshugou Area, Eastern Qinling Mountain. Acta Petrologica Sinica, 1995, 11: 127-136.

Liu Y S, Hu Z C, Gao S, . In situ Analysis of Major and Trace Elements of Anhydrous Minerals by LA-ICP-MS without Applying an Internal Standard. Chemical Geology, 2008, 257(1/2): 34-43.

Journal of Earth Science, 2018, 13 5

Malpas J, Robinson P T, Zhou M F. Chromitite and Ultramafic Rock Compositional Zoning through a Paleotransform Fault, Poum, New Caledonia: Discussion. Economic Geology, 1997, 92(4): 502-503.

Maurel C, Maurel P. Etude Experimentale de la Distribution de l’Aluminium Entre Bain Silicate Basique et Spinelle Chromifere. Implications Petrogenetiques: Teneur en Chrome des Spinelles. Bulletin de Mineralogie, 1982, 105: 197-202.

McElduff B, Stumpfl E F. The Chromite Deposits of the Troodos Complex, Cyprus-Evidence for the Role of a Fluid Phase Accompanying Chromite Formation. Mineralium Deposita, 1991, 26(4): 307-318.

Merlini A, Grieco G, Diella V. Ferritchromite and Chromian-Chlorite Formation in Melange-Hosted Kalkan Chromitite (Southern Urals, Russia). American Mineralogist, 2009, 94(10): 1459-1467.

Merlini A, Grieco G, Ottolini L, . Probe and SIMS Investigation of Clinopyroxene Inclusions in Chromites from the Troodos Chromitites (Cyprus): Implications for Dunite-Chromitite Genesis. Ore Geology Reviews, 2011, 41(1): 22-34.

Mukherjee R, Mondai S K, González-Jiménez J M, . Trace-Element Fingerprints of Chromite, Magnetite and Sulfides from the 3.1 Ga Uftramafic-mafic Rocks of the Nuggihalli Greenstone Belt, Western Dharwar Craton (India). Contributions to Mineralogy and Petrology, 2015, 169 6 59

Nie H, Yang J Z, Zhou G Y, . Geochemical and Re-Os Isotope Constraints on the Origin and Age of the Songshugou Peridotite Massif in the Qinling Orogen, Central China. Lithos, 2017, 307-319.

Ozawa K. Melting and Melt Segregation in the Mantle Wedge above a Subduction Zone: Evidence from the Chromite-Bearing Peridotites of the Miyamori Ophiolite Complex, Northeastern Japan. Journal of Petrology, 1994, 35(3): 647-678.

Pagé P, Barnes S J. Using Trace Elements in Chromites to Constrain the Origin of Podiform Chromitites in the Thetford Mines Ophiolite, Quebec, Canada. Economic Geology, 2009, 104(7): 997-1018.

Pagé P B J H, Schroetter J M, . Mantle Petrology and Mineralogy of the Thetford Mines Ophiolite Complex. Lithos, 2008, 100(1-4): 255-292.

Ratschbacher L, Hacker B R, Calvert A, . Tectonics of the Qinling (Central China): Tectonostratigraphy, Geochronology, and Deformation History. Tectonophysics, 2003, 366(1/2): 1-53.

Ren Y F, Chen F Y, Yang J S, . Exsolutions of Diopside and Magnetite in Olivine from Mantle Dunite, Luobusa Ophiolite, Tibet, China. Acta Geologica Sinica, 2008, 82(2): 377-384.

Sack R O, Ghiorso M S. Chromian Spinels as Petrogenetic Indicators: Thermodynamics and Petrological Applications. American Mineralogist, 1991, 76: 827-847.

Satsukawa T, Griffin W L, Piazolo S, . Messengers from the Deep: Fossil Wadsleyite-Chromite Microstructures from the Mantle Transition Zone. Scientific Reports, 2015, 5(1): 1-8.

Shabani T A A. Mineral Chemistry of Chlorite Replacing Biotite from Granitic Rocks of the Canadian Appalachians. Journal of Sciences, Islamic Republic of Iran, 2009, 20(3): 265-275.

Smith S E, Elthon D. Mineral Compositions of Plutonic Rocks from the Lewis Hills Massif, Bay of Islands Ophiolite. Journal of Geophysical Research, 1988, 93(B4): 3450-3468.

Song S G, Su L, Yang H Q, . Petrogenesis and Emplacement of the Songshugou Peridotite in Shangnan, Shaanxi. Acta Petrologica Sinica, 1998, 14: 212-221.

Su L, Song S G, Song B, . SHRIMP Zircon U-Pb Ages of garnet Pyroxenite and Fushui Gabbroic Complex in Songshugou Region and Constraints on Tectonic Evolution of Qinling Orogenic Belt. Chinese Science Bulletin, 2004, 49(12): 1146-1157.

Su L, Song S G, Zhou D W. Petrogenesis of Songshugou Dunite Body in the Qinling Orogenic Belt, Central China: Constraints from Geochemistry and Melt Inclusions. Science in China Series D: Earth Sciences, 2005, 48(8): 1146-1157.

Tang L, Santosh M, Dong Y P, . Early Paleozoic Tectonic Evolution of the North Qinling Orogenic Belt: Evidence from Geochemistry, Phase Equilibrium Modeling and Geochronology of Metamorphosed Mafic Rocks from the Songshugou Ophiolite. Gondwana Research, 2016, 30: 48-64.

Uysal, Tarkian M, Sadiklar M B, . Petrology of Al- and Cr-Rich Ophiolitic Chromitites from the Muğla, SW Turkey: Implications from Composition of Chromite, Solid Inclusions of Platinum-Group Mineral, Silicate, and Base-Metal Mineral, and Os-Isotope Geochemistry. Contributions to Mineralogy and Petrology, 2009, 158(5): 659-674.

Varfalvy V, Hébert R, Bédard J H. Interactions between Melt and Upper-Mantle Peridotites in the Norm Arm Mountain Massif, Bay of Islands Ophiolite, Newfoundland, Canada: Implications for the Genesis of Boninitic and Related Magmas. Chemical Geology, 1996, 129(1/2): 71-90.

Varfalvy V, Hébert R, Bédard J H. Interactions between Melt and Upper-Mantle Peridotites in the Norm Arm Mountain Massif, Bay of Islands Ophiolite, Newfoundland, Canada: Implications for the Genesis of Boninitic and Related Magmas. Chemical Geology, 1997, 129(1/2): 71-90.

Wang X B, Yang J S, Shi R D, . The Songshugou Rock Body from Qinling—A Example of Ultramafic Cumulate Undergone Amphibole Facies Metamorphism. Acta Geologica Sinica, 2005, 79: 174-189.

Wu W W, Yang J S, Dilek Y, . Multiple Episodes of Melting, Depletion, and Enrichment of the Tethyan Mantle: Petrogenesis of the Peridotites and Chromitites in the Jurassic Skenderbeu Massif, Mirdita Ophiolite, Albania. Lithosphere, 2018, 10(1): 54-78.

Xiao Y, Teng F Z, Su B X, . Iron and Magnesium Isotopic Constraints on the Origin of Chemical Heterogeneity in Podiform Chromitite from the Luobusa Ophiolite, Tibet. Geochemistry, Geophysics, Geosystems, 2016, 17(3): 940-953.

Xiong F H, Yang J S, Robinson P T, . Origin of Podiform Chromitite, a New Model Based on the Luobusa Ophiolite, Tibet. Gondwana Research, 2015, 27(2): 525-542.

Xiong F H, Yang J S, Robinson P T, . Petrology and Geochemistry of Peridotites and Podiform Chromitite in the Xigaze Ophiolite, Tibet: Implications for a Suprasubduction Zone Origin. Journal of Asian Earth Sciences, 2017, 146: 56-75.

Xiong F H, Yang J S, Dilek Y, . Origin and Significance of Diamonds and other Exotic Minerals in the Dingqing Ophiolite Peridotites, Eastern Bangong-Nujiang Suture Zone, Tibet. Lithosphere, 2017.

Xiong Q, Griffin W L, Zheng J P, . Southward Trench Migration at ~130-120 Ma Caused Accretion of the Neo-Tethyan Forearc Lithosphere in Tibetan Ophiolites. Earth and Planetary Science Letters, 2016, 438: 57-65.

Xiong Q, Henry H, Griffin W L, . High- and Low-Cr Chromitite and Dunite in a Tibetan Ophiolite: Evolution from Mature Subduction System to Incipient Forearc in the Neo-Tethyan Ocean. Contributions to Mineralogy and Petrology, 2017, 172 6 45

Yang J S, Bai W J, Fang Q S, . Discovery of Diamond and an Unusual Mineral Group from the Podiform Chromite, Polar Ural. Geology in China, 2007, 34(5): 950-952.

Yang J S, Meng F C, Xu X Z, . Diamonds, Native Elements and Metal Alloys from Chromitites of the Ray-Iz Ophiolite of the Polar Urals. Gondwana Research, 2015, 27(2): 459-485.

Yang J S, Robinson P T, Dilek Y. Diamonds in Ophiolites. Elements, 2014, 10(2): 127-130.

Yu H, Zhang H F, Li X H, . Tectonic Evolution of the North Qinling Orogen from Subduction to Collision and Exhumation: Evidence from Zircons in Metamorphic Rocks of the Qinling Group. Gondwana Research, 2016, 30(1): 65-78.

Yu H, Zhang H F, Santosh M. Mylonitized Peridotites of Songshugou in the Qinling Orogen, Central China: A Fragment of Fossil Oceanic Lithosphere Mantle. Gondwana Research, 2017, 52: 1-17.

Zaccarini F, Garuti G, Proenza J A, . Chromite and Platinum-Group-Elements Mineralization in the Santa Elena Ophiolitic Ultramafïc Nappe (Costa Rica): Geodynamic Implications. Geologica Acta, 2011, 9: 407-423.

Zanetti A, Giovanardi T, Langone A, . Origin and Age of Zircon-Bearing Chromitite Layers from the Finero Phlogopite Peridotite (Ivrea-Verbano Zone, Western Alps) and Geodynamic Consequences. Lithos, 2016, 262: 58-74.

Zang W, Fyfe W S. Chloritization of the Hydrothermally Altered Bedrock at the Igarapé Bahia Gold Deposit, Carajás, Brazil. Mineralium Deposita, 1995, 30(1): 30-38.

Zhang G W, Zhang Z Q, Dong Y P. Nature of the Main Tectono-Lithostratigraphic Units of the Qinling Orogen: Implications for the Tectonic Evolution. Acta Petrologica Sinica, 1995, 11: 101-114.

Zhang Z J. The Genesis of Dunites in the Songshugou Ultramafïc Rock Body, North Qinling. Acta Petrologica Sinica, 1995, 11: 178-189.

Zhou M F, Robinson P T M J, . Podiform Chromitites in the Luobusa Ophiolite (Southern Tibet): Implications for Melt-Rock Interaction and Chromite Segregation in the Upper Mantle. Journal of Petrology, 1996, 37(1): 3-21.

Zhou M F, Robinson P T, Malpas J, . REE and PGE Geochemical Constraints on the Formation of Dunites in the Luobusa Ophiolite, Southern Tibet. Journal of Petrology, 2005, 46(3): 615-639.

Zhou M F, Robinson P T, Su B X, . 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, 2014, 26(1): 262-283.