Abstract
Although the involvement of hydrous fluids has been widely invoked in formation of podiform chromitites in ophiolites, there is lack of natural evidence to signify the role and mechanism of fluids. In this study, a new model for the genesis of podiform chromitite is proposed on basis of revisits of comprehensive petrological, mineralogical and geochemical results of the well-preserved Kızıldağ ophiolite and the well-characterized Luobusa chromite deposit. In this model, ascending magmas intruding oceanic lithospheric mantle would presumably form a series of small magma chambers continuously connected by conduits. Tiny chromite nuclei would collect fluids dispersed in such magmas to form nascent droplets. They tend to float upward in the magma chamber and would be easily transported upward by flowing magmas. Chromite-rich droplets would be enlarged via coalescence of dispersed droplets during mingling and circulation in the magma chamber and/or transport in magma conduits. Crystallization of the chromite-rich liquid droplets would proceed from the margin of the droplet inward, leaving liquid entrapped within grains as precursor of mineral inclusions. With preferential upward transportation, immiscible chromite-rich liquids would coalesce to a large pool in a magma chamber. Large volumes of chromite would crystallize in situ, forming podiform chromitite and resulting in fluid enrichment in the chamber. The fluids would penetrate and compositionally modify ambient dunite and harzburgite, leading to significant fractionations of elemental and isotopic compositions between melts and fluids from which dunite and chromitite respectively formed. Therefore, fluid immiscibility during basaltic magma ascent plays a vital role in chromitite formation.
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References
Arai S, Miura M. 2016. Formation and modification of chromitites in the mantle. Lithos, 264: 277–295
Arai S, Yurimoto H. 1994. Podiform chromitites of the Tari-Misaka ultramafic complex, southwestern Japan, as mantle-melt interaction products. Econ Geol, 89: 1279–1288
Ballhaus C. 1998. Origin of podiform chromite deposits by magma mingling. Earth Planet Sci Lett, 156: 185–193
Bao P S, Wang X B, Peng G Y, Chen F Y. 1999. Chromite Deposit in China (in Chinese). Beijing: Science Press
Borisova A Y, Ceuleneer G, Kamenetsky V S, Arai S, Béjina F, Abily B, Bindeman I N, Polvé M, De Parseval P, Aigouy T, Pokrovski G S. 2012. A new view on the petrogenesis of the Oman ophiolite chromitites from microanalyses of chromite-hosted inclusions. J Petrol, 53: 2411–2440
Charlier B, Grove T L. 2012. Experiments on liquid immiscibility along tholeiitic liquid lines of descent. Contrib Mineral Petrol, 164: 27–44
Chen C, Su B X, Uysal I, Avcı E, Zhang P F, Xiao Y, He Y S. 2015. Iron isotopic constraints on the origin of peridotite and chromitite in the Kızıldağ ophiolite, southern Turkey. Chem Geol, 417: 115–124
Chen C, Su B X, Xiao Y, Pang K N, Robinson P T, Uysal I, Lin W, Qin K Z, Avcı E, Kapsiotis A. 2019. Intermediate chromitite in Kızıldağ ophiolite (SE Turkey) formed during subduction initiation in Neo-Tethys. Ore Geol Rev, 104: 88–100
Chen C, Su B X, Xiao Y, Uysal İ, Lin W, Chu Y, Jing J J, Sakyi P A. 2020. Highly siderophile elements and Os isotope constraints on the genesis of peridotites from the Kızıldağ ophiolite, southern Turkey. Lithos, 368–369: 105583
Chen Y, Yang J. 2018. Formation of podiform chromitite deposits: Review and prospects (in Chinese with English abstract). Earth Sci, 43: 991–1010
Dilek Y, Delaloye M. 1992. Structure of the Kızıldağ ophiolite, a slow-spread Cretaceous ridge segment north of the Arabian promontory. Geology, 20: 19–22
Dilek Y, Furnes H. 2009. Structure and geochemistry of Tethyan ophiolites and their petrogenesis in subduction rollback systems. Lithos, 113: 1–20
Fisher L W. 1929. Origin of chromite deposits. Econ Geol, 24: 691–721
Garuti G, Pushkarev E V, Zaccarini F, Cabella R, Anikina E. 2003. Chromite composition and platinum-group mineral assemblage in the Uktus Uralian-Alaskan-type complex (Central Urals, Russia). Miner Deposita, 38: 312–326
González-Jiménez J M, Griffin W L, Proenza J A, Gervilla F, O’Reilly S Y, Akbulut M, Pearson N J, Arai S. 2014. Chromitites in ophiolites: How, where, when, why? Part II. The crystallization of chromitites. Lithos, 189: 140–158
Irvine T N. 1977. Chromite crystallization in the join Mg2SiO4-CaMgSi2 O6-CaAl2Si2O8-MgCr2O4-SiO2. Carnegie Institution of Washington Yearbook, 76: 465–472
Jannessary M R, Melcher F, Lodziak J, Meisel T C. 2012. Review of platinum-group element distribution and mineralogy in chromitite ores from southern Iran. Ore Geol Rev, 48: 278–305
Johan Z, Martin R F, Ettler V. 2017. Fluids are bound to be involved in the formation of ophiolitic chromite deposits. Euro J Mineral, 29: 543–555
Kamenetsky V S, Crawford A J, Meffre S. 2001. Factors controlling chemistry of magmatic spinel: An empirical study of associated olivine, Cr-spinel and melt inclusions from primitive rocks. J Petrol, 42: 655–671
Lago B L, Rabinowicz M, Nicolas A. 1982. Podiform chromite ore bodies: A genetic model. J Petrol, 23: 103–125
Liu P P, Zhou M F, Chen W T, Boone M, Cnudde V. 2014. Using multiphase solid inclusions to constrain the origin of the baima Fe-Ti-(V) oxide deposit, SW China. J Petrol, 55: 951–976
Liu X, Su B X, Bai Y, Chen C, Xiao Y, Liang Z, Yang S H, Peng Q S, Su B C, Liu B. 2018. Ca-enrichment characteristics of parental magmas of chromitite in ophiolite: Inference from mineral inclusions (in Chinese with English abstract). Earth Sci, 43: 1038–1050
Liu X, Su B X, Bai Y, Robinson P T, Tang X, Xiao Y, Xue D S, Cui M M. 2020. Genesis of “silicate exsolution lamellae” in chromite of the Stillwater Complex: A challenge to the high-pressure crystallization of ophiolitic chromitite. Lithos, 378–379, 105796
Lorand J P, Ceuleneer G. 1989. Silicate and base-metal sulfide inclusions in chromites from the Maqsad area (Oman ophiolite, Gulf of Oman): A model for entrapment. Lithos, 22: 173–190
Macris C A, Manning C E, Young E D. 2015. Crystal chemical constraints on inter-mineral Fe isotope fractionation and implications for Fe isotope disequilibrium in San Carlos mantle xenoliths. Geochim Cosmochim Acta, 154: 168–185
Matveev S, Ballhaus C. 2002. Role of water in the origin of podiform chromitite deposits. Earth Planet Sci Lett, 203: 235–243
McDonald J A. 1965. Liquid immiscibility as one factor in chromitite seam formation in the Bushveld Igneous Complex. Econ Geol, 60: 1674–1685
Melcher F, Grum W, Simon G, Thalhammer T V, Stumpfl E F. 1997. Petrogenesis of the ophiolitic giant chromite deposits of Kempirsai, Kazakhstan: A study of solid and fluid inclusions in chromite. J Petrol, 38: 1419–1458
Menzies M A, Hawkesworth C J. 1987. Mantle Metasomatism. London: Academic Press
Pagé P, Barnes S J. 2009. Using trace elements in chromites to constrain the origin of podiform chromitites in the Thetford Mines ophiolite, Quebec, Canada. Econ Geol, 104: 997–1018
Prichard H M, Barnes S J, Godel B, Reddy S M, Vukmanovic Z, Halfpenny A, Neary C R, Fisher P C. 2015. The structure of and origin of nodular chromite from the Troodos ophiolite, Cyprus, revealed using highresolution X-ray computed tomography and electron backscatter diffraction. Lithos, 218–219: 87–98
Robinson P T, Bai W J, Malpas J, Yang J S, Zhou M F, Fang Q S, Hu X F, Cameron S, Staudigel H. 2004. Ultra-high pressure minerals in the Luobusa ophiolite, Tibet, and their tectonic implications. Geol Soc London Spec Publ, 226: 247–271
Robinson P T, Trumbull R B, Schmitt A, Yang J S, Li J W, Zhou M F, Erzinger J, Dare S, Xiong F. 2015. The origin and significance of crustal minerals in ophiolitic chromitites and peridotites. Gondwana Res, 27: 486–506
Rollinson H, Mameri L, Barry T. 2018. Polymineralic inclusions in mantle chromitites from the Oman ophiolite indicate a highly magnesian parental melt. Lithos, 310–311: 381–391
Roskosz M, Sio C K I, Dauphas N, Bi W, Tissot F L H, Hu M Y, Zhao J, Alp E E. 2015. Spinel-olivine-pyroxene equilibrium iron isotopic fractionation and applications to natural peridotites. Geochim Cosmochim Acta, 169: 184–199
Sachan H K, Mukherjee B K, Bodnar R J. 2007. Preservation of methane generated during serpentinization of upper mantle rocks: Evidence from fluid inclusions in the Nidar ophiolite, Indus suture zone, Ladakh (India). Earth Planet Sci Lett, 257: 47–59
Saka S, Uysal I, Kapsiotis A, Bağcı U, Ersoy E Y, Su B X, Seitz H M, Hegner E. 2019. Petrological characteristics and geochemical compositions of the Neotethyan Mersin ophiolite (southern Turkey): Processes of melt depletion, refertilization, chromitite formation and oceanic crust generation. J Asian Earth Sci, 176: 281–299
Smith D R, Leeman W P. 2005. Chromian spinel-olivine phase chemistry and the origin of primitive basalts of the southern Washington Cascades. J Volcanol Geotherm Res, 140: 49–66
Su B X, Bai Y, Chen C, Liu X, Xiao Y, Tang D M, Liang Z, Cui M M, Peng Q S. 2018a. Petrological and mineralogical investigations on hydrous property of parental magmas of chromite deposits (in Chinese with English abstract). Bull Mineral Petrol Geochem, 37: 1035–1046
Su B X, Chen C, Pang K N, Sakyi P A, Uysal I, Avci E, Liu X, Zhang P F. 2018b. Melt penetration in oceanic lithosphere: Li isotope records from the Pozantı-Karsantı ophiolite in southern Turkey. J Petrol, 59: 191–205
Su B X, Zhou M F, Jing J J, Robinson P T, Chen C, Xiao Y, Liu X, Shi R D, Lenaz D, Hu Y. 2019. Distinctive melt activity and chromite mineralization in Luobusa and Purang ophiolites, southern Tibet: Constraints from trace element compositions of chromite and olivine. Sci Bull, 64: 108–121
Su B X, Zhou M F, Robinson P T. 2016. Extremely large fractionation of Li isotopes in a chromitite-bearing mantle sequence. Sci Rep, 6: 22370
Su B X, Robinson P T, Chen C, Xiao Y, Melcher F, Bai Y, Gu X Y, Uysal I, Lenaz D. 2020. The occurrence, origin, and fate of water in chromitites in ophiolites. Am Miner, 105: 894–903
Uysal I, Tarkian M, Sadiklar M B, Zaccarini F, Meisel T, Garuti G, Heidrich S. 2009. 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. Contrib Mineral Petrol, 158: 659–674
Xiao Y, Teng F Z, Su B X, Hu Y, Zhou M F, Zhu B, Shi R D, Huang Q S, Gong X H, He Y S. 2016. Iron and magnesium isotopic constraints on the origin of chemical heterogeneity in podiform chromitite from the Luobusa ophiolite, Tibet. Geochem Geophys Geosyst, 17: 940–953
Xiao Y, Zhang H F, Fan W M, Ying J F, Zhang J, Zhao X M, Su B X. 2010. Evolution of lithospheric mantle beneath the Tan-Lu fault zone, eastern North China Craton: Evidence from petrology and geochemistry of peridotite xenoliths. Lithos, 117: 229–246
Xiong F, Yang J, Robinson P T, Xu X, Liu Z, Li Y, Li J, Chen S. 2015. Origin of podiform chromitite, a new model based on the Luobusa ophiolite, Tibet. Gondwana Res, 27: 525–542
Xiong F H, Yang J S, Robinson P T, Xu X Z, Ba D Z, Li Y, Zhang Z M, Rong H. 2016. Diamonds and other exotic minerals recovered from peridotites of the Dangqiong ophiolite, western Yarlung-Zangbo suture zone, Tibet. Acta Geol Sin, 90: 425–439
Yang J S, Dobrzhinetskaya L, Bai W J, Fang Q S, Robinson P T, Zhang J, Green H W. 2007. Diamond- and coesite-bearing chromitites from the Luobusa ophiolite, Tibet. Geology, 35: 875–878
Yang J S, Robinson P T, Dilek Y. 2015. Diamond-bearing ophiolites and their geological occurrence. Episodes, 38: 344–364
Zhang P F, Zhou M F, Su B X, Uysal I, Robinson P T, Avcı E, He Y S. 2017. Iron isotopic fractionation and origin of chromitites in the paleo-Moho transition zone of the Kop ophiolite, NE Turkey. Lithos, 268–271: 65–75
Zhao X, Zhang H, Zhu X, Tang S, Yan B. 2012. Iron isotope evidence for multistage melt-peridotite interactions in the lithospheric mantle of eastern China. Chem Geol, 292–293: 127–139
Zhou M F, Robinson P T, Bai W J. 1994. Formation of podiform chromitites by melt/rock interaction in the upper mantle. Mineral Deposita, 29: 98–101
Zhou M F, Robinson P T, Malpas J, Edwards S J, Qi L. 2005. REE and PGE geochemical constraints on the formation of dunites in the Luobusa ophiolite, southern Tibet. J Petrol, 46: 615–639
Zhou M F, Robinson P T, Malpas J, Li Z. 1996. Podiform Chromitites in the Luobusa Ophiolite (Southern Tibet): Implications for melt-rock interaction and chromite segregation in the upper mantle. J Petrol, 37: 3–21
Zhou M F, Robinson P T, Su B X, Gao J F, Li J W, Yang J S, 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 Res, 26: 262–283
Acknowledgements
We appreciate Davide Lenaz and another anonymous reviewer for their constructive comments, which significantly improved the manuscript. This work was supported by the National Natural Science Foundation of China (Grant Nos. 91755205, 41973012, and 41772055).
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Su, B., Liu, X., Chen, C. et al. A new model for chromitite formation in ophiolites: Fluid immiscibility. Sci. China Earth Sci. 64, 220–230 (2021). https://doi.org/10.1007/s11430-020-9690-4
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DOI: https://doi.org/10.1007/s11430-020-9690-4