FTIR study of H2O in silicate minerals and mineral inclusions in chromite from the peridotite zone of the Stillwater complex (Montana, USA): Evidence for chromitite formation in an H2O-rich environment
Bai, Yang; Cui, Meng-Meng; Su, Ben-Xunet al.
2024 • In Geological Society of America Bulletin, 136 (3-4), p. 1661 - 1674
Chromitites; Clinopyroxenes; Hydrous fluids; Interstitials; Layered intrusions; Magma differentiation; Mineral inclusions; Montana; Orthopyroxene; Stratiforms; Geology
Abstract :
[en] Although the involvement of hydrous fluids has been frequently invoked in the formation of stratiform chromitites in layered intrusions, there is a lack of natural evidence to signify their presence and mechanism. Here, Fourier-transform infrared spectroscopy (FTIR) of H2O in silicate minerals in the lowermost layer and G chromitite layer of the Stillwater complex, Montana, USA, shows that olivine grains have 20–55 ppm H2O, orthopyroxene has 30–45 ppm H2O, and clinopyroxene has 144–489 ppm H2O. The jointly increasing H2O contents of olivine and orthopyroxene in silicate cumulates along with magma differentiation record a negative correlation in chromitites. On the basis of poikilitic clinopyroxene, we calculated that the interstitial melts had averages of 1.3 wt% and 2.3 wt% H2O in dunite and chromitite, respectively, showing significant differences between chromitites and silicate cumulates. More than 10% of the chromite grains contained polymineralic inclusions up to 100 μm in size that were composed mainly of orthopyroxene, hornblende, plagioclase, and phlogopite. Most of these minerals were characterized by higher MgO and fluid-mobile element contents, such as Na and K, than minerals in associated silicates. Based on the mineral modes of the hydrous phases and their compositions, the trapped fluids contained ∼2.6 wt% H2O, consistent with the FTIR estimates, indicating the inclusion compositions represent interstitial melts instead of parental magmas. These observations indicate that the chromite microlites collected fluids during early crystallization, leading to a heterogeneous fluid redistribution in the melt. The fluids were collected on the surface of chromite grains during crystallization and then dissolved into poikilitic pyroxene. Chromite grains could also be efficiently floated by these fluids, causing them to migrate away from the silicate minerals in the magma channel and leading to the formation of nearly monomineralic chromitite seams. This process serves as a kinetic model indicating that chromite could be completely separated from silicates during mechanical sorting in layered intrusions.
Disciplines :
Earth sciences & physical geography
Author, co-author :
Bai, Yang ; Department of Earth Science and Engineering, Taiyuan University of Technology, Taiyuan, China ; Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China ; Department of Geology, University of Liege, Liege, Belgium
Cui, Meng-Meng; Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
Su, Ben-Xun ; Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China ; University of Chinese Academy of Sciences, Beijing, China
Liu, Xia; Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China ; University of Chinese Academy of Sciences, Beijing, China
Xiao, Yan; State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
Robinson, Paul T.; Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
Gu, Xiao-Yan; School of Earth Sciences, Zhejiang University, Hangzhou, China
Language :
English
Title :
FTIR study of H2O in silicate minerals and mineral inclusions in chromite from the peridotite zone of the Stillwater complex (Montana, USA): Evidence for chromitite formation in an H2O-rich environment
Publication date :
2024
Journal title :
Geological Society of America Bulletin
ISSN :
0016-7606
eISSN :
1943-2674
Publisher :
Geological Society of America
Volume :
136
Issue :
3-4
Pages :
1661 - 1674
Peer reviewed :
Peer Reviewed verified by ORBi
Funding text :
We thank Bernard Charlier for comments on the original manuscript, two anonymous reviewers for providing insightful and constructive reviewer comments that significantly improved our manuscript, and the associate editor for handling the paper and providing very helpful additional comments. This study was financially supported by the Second Tibetan Plateau Scientific Expedition and Research Program (STEP) (2019QZKK0802), the National Natural Science Foundation of China (91755205 and 41772055), and the Youth Innovation Promotion Association, Chinese Academy of Sciences (2016067).
Alapieti, T.T., Kujanpaa, J., Lahtinen, J.J., and Papunen, H., 1989, The Kemi stratiform chromitite deposit, northern Finland: Economic Geology, v. 84, p. 1057–1077, https://doi.org/10.2113/gsecongeo.84.5.1057.
Asimow, P.D., Stein, L.C., Mosenfelder, J.L., and Rossman, G.R., 2006, Quantitative polarized infrared analysis of trace OH in populations of randomly oriented mineral grains: The American Mineralogist, v. 91, p. 278–284, https://doi.org/10.2138/am.2006.1937.
Bai, Y., Su, B.X., Chen, C., Yang, S.H., Liang, Z., Xiao, Y., Qin, K.Z., and Malaviarachchi, S.P., 2017, Base metal mineral segregation and Fe-Mg exchange inducing extreme compositions of olivine and chromite from the Xiadong Alaskan-type complex in the southern part of the Central Asian orogenic belt: Ore Geology Reviews, v. 90, p. 184–192, https://doi.org/10.1016/j.oregeorev.2017.01.023.
Bai, Y., Su, B.X., Xiao, Y., Lenaz, D., Asamoah Sakyi, P., Liang, Z., Chen, C., and Yang, S.H., 2018, Origin of reverse zoned Cr-spinels from the Paleoproterozoic Yanmenguan mafic-ultramafic complex in the North China craton: Minerals (Basel), v. 8, p. 62–77, https://doi.org/10.3390/min8020062.
Bai, Y., Su, B.X., Xiao, Y., Chen, C., Cui, M.M., He, X.Q., Qin, L.P., and Charlier, B., 2019, Chromium inter-mineral diffusion in ultramafic cumulates: Elemental and isotopic evidence from the Stillwater complex: Geochimica et Cosmochimica Acta, v. 263, p. 167–181, https://doi.org/10.1016/j.gca.2019.07.052.
Bai, Y., Su, B.X., Xiao, Y., Cui, M.M., and Charlier, B., 2021, Magnesium and iron isotopic evidence of inter-mineral diffusion in ultramafic cumulates of the peridotite zone, Stillwater complex: Geochimica et Cosmochimica Acta, v. 292, p. 152–169, https://doi.org/10.1016/j.gca.2020.09.023.
Ballhaus, C., 1998, Origin of podiform chromite deposits by magma mingling: Earth and Planetary Science Letters, v. 156, p. 185–193, https://doi.org/10.1016/S0012 -821X(98)00005-3.
Ballhaus, C., Fonseca, R.O., Münker, C., Kirchenbaur, M., and Zirner, A., 2015, Spheroidal textures in igneous rocks—Textural consequences of H2O saturation in basaltic melts: Geochimica et Cosmochimica Acta, v. 167, p. 241–252, https://doi.org/10.1016/j.gca.2015.07.029.
Barnes, S.J., 1998, Chromite in komatiites: 1. Magmatic controls on crystallization and composition: Journal of Petrology, v. 39, p. 1689–1720, https://doi.org/10.1093/petroj/39.10.1689.
Barnes, S.J., and Naldrett, A.J., 1985, Geochemistry of the J-M (Howland) Reef of the Stillwater complex, Minneapolis Adit area; I. Sulfide chemistry and sulfide-olivine equilibrium: Economic Geology, v. 80, p. 627–645, https://doi.org/10.2113/gsecongeo.80.3.627.
Barnes, S.J., and Naldrett, A.J., 1986, Geochemistry of the J-M Reef of the Stillwater complex, Minneapolis Adit area II. Silicate mineral chemistry and petrogenesis: Journal of Petrology, v. 27, p. 791–825, https://doi.org/10.1093/petrology/27.4.791.
Barnes, S.J., Pagé, P., Prichard, H.M., Zientek, M.L., and Fisher, P.C., 2016, Chalcophile and platinum-group element distribution in the ultramafic series of the Stillwater complex, MT, USA—Implications for processes enriching chromite layers in Os, Ir, Ru, and Rh: Mineralium Deposita, v. 51, p. 25–47, https://doi.org/10.1007/s00126-015-0587-y.
Bell, D.R., and Rossman, G.R., 1992, Water in Earth’s mantle: The role of nominally anhydrous minerals: Science, v. 255, p. 1391–1397, https://doi.org/10.1126/science.255.5050.1391.
Bell, D.R., Ihinger, P.D., and Rossman, G.R., 1995, Quantitative analysis of hydroxyl in garnet and pyroxene: The American Mineralogist, v. 80, p. 465–474, https://doi.org/10.2138/am-1995-5-607.
Botcharnikov, R.E., Almeev, R.R., Koepke, J., and Holtz, F., 2008, Phase relations and liquid lines of descent in hydrous ferrobasalt—Implications for the Skaergaard intrusion and Columbia River flood basalts: Journal of Petrology, v. 49, p. 1687–1727, https://doi.org/10.1093/petrology/egn043.
Bottinga, Y., and Javoy, M., 1990, MORB degassing: Bubble growth and ascent: Chemical Geology, v. 81, p. 255–270, https://doi.org/10.1016/0009-2541(90)90050-H.
Boudreau, A.E., 2011, The evolution of texture and layering in layered intrusions: International Geology Review, v. 53, p. 330–353, https://doi.org/10.1080/00206814.2010.496163.
Boudreau, A.E., 2016, The Stillwater complex, Montana—Overview and the significance of volatiles: Mineralogical Magazine, v. 80, p. 585–637, https://doi.org/10.1180/minmag.2016.080.063.
Boudreau, A.E., 2019, Hydromagmatic Processes and Platinum-Group Element Deposits in Layered Intrusions: Cambridge, UK, Cambridge University Press, 275 p., https://doi.org/10.1017/9781108235617.
Boudreau, A.E., and McCallum, I.S., 1992, Concentration of platinum-group elements by magmatic fluids in layered intrusions: Economic Geology, v. 87, p. 1830–1848, https://doi.org/10.2113/gsecongeo.87.7.1830.
Boudreau, A.E., Mathez, E.A., and McCallum, I.S., 1986, Halogen geochemistry of the Stillwater and Bushveld complexes: Evidence for transport of the platinum-group elements by Cl-rich fluids: Journal of Petrology, v. 27, p. 967–986, https://doi.org/10.1093/petrology/27.4.967.
Boudreau, A.E., Stewart, M.A., and Spivack, A.J., 1997, Stable Cl isotopes and origin of high-Cl magmas of the Stillwater complex, Montana: Geology, v. 25, p. 791–794, https://doi.org/10.1130/0091-7613(1997)025<0791:SCIAOO>2.3.CO;2.
Butcher, A.R., 1985, Channeled metasomatism in Rhum layered cumulates—Evidence from late-stage veins: Geological Magazine, v. 122, p. 503–518, https://doi.org/10.1017/S0016756800035421.
Campbell, I.H., and Murck, B.W., 1993, Petrology of the G and H chromitite zones in the Mountain View area of the Stillwater complex, Montana: Journal of Petrology, v. 34, p. 291–316, https://doi.org/10.1093/petrology/34.2.291.
Carman, J.H., 1974, Synthetic sodium phlogopite and its two hydrates: The American Mineralogist, v. 59, p. 261–273.
Cawthorn, R.G., and O’Hara, M.J., 1976, Amphibole fractionation in calc-alkaline magma genesis: American Journal of Science, v. 276, p. 309–329, https://doi.org/10.2475/ajs.276.3.309.
Cawthorn, R.G., Barnes, S.J., Ballhaus, C., and Malitch, K.N., 2005, Platinum group element, chromium, and vanadium deposits in mafic and ultramafic rocks, in Raeside, R., ed., Exploration for Platinum-Group Elements: Mineralogical Society of Canada Short Course 35, p. 215–249, https://doi.org/10.5382/AV100.09.
Chalmers, B., 1964, Principles of Solidification: New York, John Wiley and Sons., 319 p.
Chistyakova, S.Y., Latypov, R.M., and Zaccarini, F., 2015, Chromitite dykes in the Monchegorsk layered intrusion, Russia: In situ crystallization from chromite-saturated magma flowing in conduits: Journal of Petrology, v. 56, p. 2395–2424, https://doi.org/10.1093/petrology/egv079.
Cichy, S.B., Botcharnikov, R.E., Holtz, F., and Behrens, H., 2011, Vesiculation and microlite crystallization induced by decompression: A case study of the 1991–1995 Mt Unzen eruption (Japan): Journal of Petrology, v. 52, p. 1469–1492, https://doi.org/10.1093/petrology/egq072.
Cooper, R.W.L., 1997, Magmatic unconformities and stratigraphic relations in the peridotite zone, Stillwater complex, Montana: Canadian Journal of Earth Sciences, v. 34, p. 407–425, https://doi.org/10.1139/e17-035.
Czamanske, G.K., and Zientek, M.L., 1985, The Stillwater Complex, Montana: Geology and Guide: Montana Bureau of Mines and Geology Special Publication 92, 396 p.
Deer, W.A., Howie, R.A., and Zussman, J., 1992, An Introduction to the Rock-Forming Minerals (2nd ed.): New York, Longman, 696 p.
Dixon, J.E., Stolper, E.M., and Holloway, J.R., 1995, An experimental study of water and carbon dioxide solubilities in mid-ocean ridge basaltic liquids. Part I: Calibration and solubility models: Journal of Petrology, v. 36, p. 1607–1631, https://doi.org/10.1093/oxfordjournals.petrology.a037267.
Dixon, J.E., Clague, D.A., Wallace, P., and Poreda, R., 1997, Volatiles in alkalic basalts from the North Arch volcanic field, Hawaii: Extensive degassing of deep submarine-erupted alkalic series lavas: Journal of Petrology, v. 38, p. 911–939, https://doi.org/10.1093/petroj/38.7.911.
Dixon, J.E., Dixon, T.H., Bell, D.R., and Malservisi, R., 2004, Lateral variation in upper mantle viscosity: Role of water: Earth and Planetary Science Letters, v. 222, p. 451–467, https://doi.org/10.1016/j.epsl.2004.03.022.
Donaldson, C.H., 1975, Ultrabasic breccias in layered intrusions—The Rhum complex: The Journal of Geology, v. 83, p. 33–45, https://doi.org/10.1086/628043.
Eales, H.V., 1987, Upper critical zone chromitite layers at RPM Union section mine, western Bushveld complex, in Stowe, C.W., ed., Evolution of Chromium Ore Fields: New York, Van Nostrand Reinhold, p. 144–168.
Eales, H.V., and Costin, G., 2012, Crustally contaminated komatiite: Primary source of the chromitites and marginal, lower, and critical zone magmas in a staging chamber beneath the Bushveld complex: Economic Geology, v. 107, p. 645–665, https://doi.org/10.2113/econgeo.107.4.645.
Edmonds, M., Brett, A., Herd, R.A., Humphreys, M.C.S., and Woods, A., 2015, Magnetite-bubble aggregates at mixing interfaces in andesite magma bodies, in Zellmer, G.F., Edmonds, M., and Straub, S.M., eds., The Role of Volatiles in the Genesis, Evolution and Eruption of Arc Magmas: Geological Society, London, Special Publication 410, p. 95–121, https://doi.org/10.1144/SP410.7.
Edwards, S.J., Pearce, J.A., and Freeman, J., 2000, New insights concerning the influence of water during the formation of podiform chromite, in Dilek, Y., Moores, E.M., Elthon, D., and Nicolas, A., eds., Ophiolites and Oceanic Crust: New Insights from Field Studies and the Ocean Drilling Program: Geological Society of America Special Paper 349, p. 139–147, https://doi.org/10.1130/0-8137-2349-3.139.
Emeleus, C.H., Cheadle, M.J., Hunter, R.H., Upton, B.G.J., and Wadsworth, W.J., 1996, The Rum layered suite, in Cawthorn, R.G., ed., Layered Intrusions: Amsterdam, Netherlands, Elsevier, Developments in Petrology 15, p. 403–439, https://doi.org/10.1016/S0167-2894(96) 80014–5.
Feig, S.T., Koepke, J., and Snow, J.E., 2010, Effect of oxygen fugacity and water on phase equilibria of a hydrous tholeiitic basalt: Contributions to Mineralogy and Petrology, v. 160, p. 551–568, https://doi.org/10.1007/s00410-010-0493-3.
Fiege, A., Holtz, F., and Cichy, S.B., 2014, Bubble formation during decompression of andesitic melts: The American Mineralogist, v. 99, p. 1052–1062, https://doi.org/10.2138/am.2014.4719.
Ford, C.E., Biggar, G.M., Humphries, D.J., Wilson, G., Dixon, D., and O’Hara, M.J., 1972, Role of water in the evolution of the lunar crust: An indication of lunar calc-alkaline volcanism: Proceedings of the Third Lunar Science Conference: Geochimica et Cosmochimica Acta, v. 1, Supplement 3, p. 207–229.
Forien, M., Tremblay, J., Barnes, S.J., Burgisser, A., and Page, P., 2015, The role of viscous particle segregation in forming chromite layers from slumped crystal slurries: Insights from analogue experiments: Journal of Petrology, v. 56, p. 2425–2444, https://doi.org/10.1093/petrology/egv060.
Friedrich, B.M., Marques, J.C., Olivo, G.R., Frantz, J.C., Joy, B., and Waldemir, J.A.Q., 2019, Petrogenesis of the massive chromitite layer from the Jacurici complex, Brazil: Evidence from inclusions in chromite: Mineralium Deposita, v. 4, p. 1–22, https://doi.org/10.1007/s00126-019-00917-0.
Gaetani, G.A., and Grove, T.L., 1998, The influence of water on melting of mantle peridotite: Contributions to Mineralogy and Petrology, v. 131, p. 323–346, https://doi.org/10.1007/s004100050396.
Ghiorso, M.S, and Gualda, G.A., 2013, A method for estimating the activity of titania in magmatic liquids from the compositions of coexisting rhombohedral and cubic iron–titanium oxides: Contributions to Mineralogy and Petrology, v. 165, p. 73–81, https://doi.org/10.1007/s00410-012-0792-y.
Giachetti, T., Gonnermann, H.M., Gardner, J.E., Burgisser, A., Hajimirza, S., Earley, T.C., Truong, N., and Toledo, P., 2019, Bubble coalescence and percolation threshold in expanding rhyolitic magma: Geochemistry, Geophysics, Geosystems, v. 20, p. 1054–1074, https://doi.org/10.1029/2018GC008006.
Grant, K.J., Ingrin, J., Lorland, J.P., and Dumas, P., 2007, Water partition between mantle minerals from peridotite xenoliths: Contributions to Mineralogy and Petrology, v. 154, p. 15–34, https://doi.org/10.1007/s00410-006-0177-1.
Greenbaum, D., 1977, The chromitiferous rocks of the Troodos ophiolite, Cyprus: Economic Geology, v. 72, p. 1175–1194, https://doi.org/10.2113/gsecongeo.72.7.1175.
Gualda, G.A., and Ghiorso, M.S., 2007, Magnetite scavenging and the buoyancy of bubbles in magmas. Part II: Energetics of crystal-bubble attachment in magmas: Contributions to Mineralogy and Petrology, v. 154, p. 479–490, https://doi.org/10.1007/s00410-007 -0206-8.
Hamlyn, P.R., and Keays, R.R., 1986, Sulfur saturation and second-stage Melts: Application to the Bushveld platinum metal deposits: Economic Geology, v. 81, p. 1431–1445, https://doi.org/10.2113/gsecongeo.81.6.1431.
Hao, Y., Xia, Q., Li, Q., Chen, H., and Feng, M., 2014, Partial melting control of water contents in the Cenozoic lithospheric mantle of the Cathaysia block of South China: Chemical Geology, v. 380, p. 7–19, https://doi.org/10.1016/j.chemgeo.2014.04.017.
He, L.F., Hu, X.M., Zha, Y.B., Xu, L.G., and Wang, Y.H., 2014, Distribution and origin of high magnetic anomalies at Luobusa ophiolite in southern Tibet: Science Bulletin, v. 59, p. 2898–2908, https://doi.org/10.1007/s11434-014-0330-6.
He, L.F., Chen, L., Dorji, He, Z.X., Wang, X.B., Xiao, B.Y., Xu, L.G., Zhao, X.F., Xi, X.L., Yao, H.C., and Chen, R.J., 2018, Mapping chromite deposits with audio mag-netotellurics in the Luobusa ophiolite of southern Tibet: Geophysics, v. 83, p. B47–B57, https://doi.org/10.1190/geo2017-0110.1.
Helz, R.T., 1995, The Stillwater complex, Montana: A subvolcanic magma chamber: The American Mineralogist, v. 80, p. 1343–1346, https://doi.org/10.2138/am-1995-11-1225.
Hess, H.H., 1960, Stillwater Igneous Complex, Montana: A Quantitative Mineralogical Study: Geological Society of America Memoir 80, 230 p., https://doi.org/10.1130/MEM80-p1.
Horan, M.F., Morgan, J.W., Walker, R.J., and Cooper, R.W., 2001, Re-Os isotopic constraints on magma mixing in the peridotite zone of the Stillwater complex, Montana, USA: Contributions to Mineralogy and Petrology, v. 141, p. 446–457, https://doi.org/10.1007/s004100100251.
Howland, A.L., Garrels, E.M., and Jones, W.R., 1949, Chromite Deposits of Boulder River Area, Sweetgrass County, Montana: U.S. Geological Survey Bulletin 948-C, 24 p., https://pubs.usgs.gov/bul/0948c/report.pdf.
Hurwitz, S., and Navon, O., 1994, Bubble nucleation in rhyolitic melts: Experiments at high pressure, temperature, and water content: Earth and Planetary Science Letters, v. 122, p. 267–280, https://doi.org/10.1016/0012 -821X(94)90001-9.
Irvine, T.N., 1975, Crystallization sequences in the Muskox intrusion and other layered intrusions: II. Origin of chromitite layers and similar deposits of other magmatic ores: Geochimica et Cosmochimica Acta, v. 39, p. 991–1020, https://doi.org/10.1016/0016 -7037(75)90043-5.
Irvine, T.N., 1977, Origin of chromitite layers in the Muskox intrusion and other stratiform intrusions: A new interpretation: Geology, v. 5, p. 273–277, https://doi.org/10.1130/0091-7613(1977)5<273:OOCLIT>2.0.CO;2.
Irvine, T.N., 1982, Terminology for layered intrusions: Journal of Petrology, v. 23, p. 127–162, https://doi.org/10.1093/petrology/23.2.127-a.
Jackson, E.D., 1961, Primary Textures and Mineral Associations in the Ultramafic Zone of the Stillwater Complex, Montana: U.S. Geological Survey Professional Paper 358, 106 p., https://doi.org/10.3133/pp358.
Jenkins, M.C., and Mungall, J.E., 2018, Genesis of the peridotite zone, Stillwater complex, Montana, USA: Journal of Petrology, v. 59, p. 2157–2189, https://doi.org/10.1093/petrology/egy093.
Johan, Z., Martin, R.F., and Ettler, V., 2017, Fluids are bound to be involved in the formation of ophiolitic chromite deposits: European Journal of Mineralogy, v. 29, p. 543–555, https://doi.org/10.1127/ejm/2017/0029-2648.
Jones, W.R., Peoples, J.W., and Howland, A.L., 1960, Igneous and Tectonic Structures of the Stillwater Complex, Montana: U.S. Geological Survey Bulletin 1071-H, p. 281–340, https://pubs.usgs.gov/bul/1071 h/report.pdf.
Kaufmann, F.E.D., Vukmanovic, Z., Holness, M.B., and Hecht, L., 2018, Orthopyroxene oikocrysts in the MG1 chromitite layer of the Bushveld complex: Implications for cumulate formation and recrystallization: Contributions to Mineralogy and Petrology, v. 173, 17, https:// doi.org/10.1007/s00410-018-1441-x.
Knipping, J.L., Bilenker, L.D., Simon, A.C., Reich, M., Barra, F., Deditius, A.P., Lundstrom, C., Bindeman, I., and Munizaga, R., 2015, Giant Kiruna-type deposits form by efficient flotation of magmatic magnetite suspensions: Geology, v. 43, p. 591–594, https://doi.org/10.1130/G36650.1.
Knipping, J.L., Webster, J.D., Simon, A.C., and Holtz, F., 2019, Accumulation of magnetite by flotation on bubbles during decompression of silicate magma: Scientific Reports, v. 9, 3852, https://doi.org/10.1038/s41598 -019-40376-1.
Kovács, I., O’Neill, H.S.C., Hermann, J., and Hauri, E.H., 2010, Site-specific infrared OH absorption coefficients for water substitution into olivine: The American Mineralogist, v. 95, p. 292–299, https://doi.org/10.2138/am.2010.3313.
Labotka, T.C., and Kath, R.L., 2001, Petrogenesis of the contact-metamorphic rocks beneath the Stillwater complex, Montana: Geological Society of America Bulletin, v. 113, p. 1312–1323, https://doi.org/10.1130/0016-7606(2001)113<1312:POTCMR>2.0.CO;2.
Latypov, R., and Chistyakova, S., 2020, Origin of non-cotectic cumulates: A novel approach: Geology, v. 48, p. 604–608, https://doi.org/10.1130/G47082.1.
Latypov, R., Chistyakova, S., Barnes, S.J., and Hunt, M., 2017, Origin of platinum deposits in layered intrusions by in situ crystallization: Evidence from undercutting Merensky Reef of the Bushveld complex: Journal of Petrology, v. 58, p. 715–761, https://doi.org/10.1093/petrology/egx032.
Latypov, R., Costin, G., Chistyakova, S., Hunt, E.J., Mukherjee, R., and Naldrett, T., 2018, Platinum-bearing chromite layers are caused by pressure reduction during magma ascent: Nature Communications, v. 9, 462, https://doi.org/10.1038/s41467-017-02773-w.
Leroy, L.W., 1985, Troctolite-anorthosite zone I and the J-M reef: Frog Pond Adit to Graham Creek area, in Czamanske, G.K., and Zientek, M.L., eds., Stillwater Complex: Montana Bureau of Mines and Geology Special Publication 92, p. 325–333.
Lesher, C.M., Carson, H.J.E., and Houlé, M.G., 2019, Genesis of chromite deposits by dynamic upgrading of Fe ± Ti oxide xenocrysts: Geology, v. 47, p. 207–210, https://doi.org/10.1130/G45448.1.
Li, C., Ripley, E.M., Sarkar, A., Shin, D., and Maier, W.D., 2005, Origin of phlogopite-orthopyroxene inclusions in chromites from the Merensky Reef of the Bushveld complex, South Africa: Contributions to Mineralogy and Petrology, v. 150, p. 119–130, https://doi.org/10.1007/s00410-005-0013-z.
Li, P., Scott, J.M., Liu, J., and Xia, Q.K., 2018, Lateral H2O variation in the Zealandia lithospheric mantle controls orogen width: Earth and Planetary Science Letters, v. 502, p. 200–209, https://doi.org/10.1016/j.epsl.2018.09.004.
Liang, Z., Xiao, Y., Thakurta, J., Su, B.X., Chen, C., Bai, Y., and Sakyi, P.A., 2018, Exsolution lamellae in olivine grains of dunite units from different types of mafic-ultramafic complexes: Acta Geologica Sinica, v. 92, p. 586–599, https://doi.org/10.1111/1755-6724.13544.
Libowitzky, E., and Rossman, G.R., 1996, Principles of quantitative absorbance measurements in anisotropic crystals: Physics and Chemistry of Minerals, v. 23, p. 319–327, https://doi.org/10.1007/BF00199497.
Libowitzky, E., and Rossman, G.R., 1997, An IR absorption calibration for water in minerals: The American Mineralogist, v. 82, p. 1111–1115, https://doi.org/10.2138/am-1997-11-1208.
Lipin, B.R., 1993, Pressure increases, the formation of chromite seams, and the development of the ultramafic series in the Stillwater complex, Montana: Journal of Petrology, v. 34, p. 955–976, https://doi.org/10.1093/petrology/34.5.955.
Liu, X., Su, B.X., Xiao, Y., Chen, C., Uysal, I., Jing, J.J., Zhang, P.F., Chu, Y., Lin, W., and Sakyi, P.A., 2019, Initial subduction of Neo-Tethyan ocean: Geochemical records in chromite and mineral inclusions in the Pozantı-Karsantı ophiolite, southern Turkey: Ore Geology Reviews, v. 110, 102926, https://doi.org/10.1016/j.oregeorev.2019.05.012.
Lorand, J.P., and 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, v. 22, p. 173–190, https://doi.org/10.1016/0024-4937(89)90054-6.
Luth, W.C., 1967, Studies in the system KAlSiO4-Mg2SiO4SiO2-H2O, inferred phase relations and petrologic implications: Journal of Petrology, v. 8, p. 372–416, https://doi.org/10.1093/petrology/8.3.372.
Maier, W.D., Barnes, S.J., and Groves, D.I., 2013, The Bushveld complex, South Africa: Formation of platinum-palladium, chrome- and vanadium-rich layers via hydrodynamic sorting of a mobilized cumulate slurry in a large, relatively slowly cooling, subsiding magma chamber: Mineralium Deposita, v. 48, p. 1–56, https://doi.org/10.1007/s00126-012-0436-1.
Mathez, E.A., Hunter, R.H., and Kinzler, R., 1997, Petrologic evolution of partially molten cumulate: The Atok section of the Bushveld complex: Contributions to Mineralogy and Petrology, v. 129, p. 20–34, https://doi.org/10.1007/s004100050320.
Mattsson, T., 2014, The Roots of a Magma Chamber, the Central Intrusion, Rum, NW-Scotland [Master’s thesis]: Uppsala, Sweden, Uppsala University, 107 p.
Matveev, S., and Ballhaus, C., 2002, Role of water in the origin of podiform chromitite deposits: Earth and Planetary Science Letters, v. 203, p. 235–243, https://doi.org/10.1016/S0012-821X(02)00860-9.
McCallum, I.S., 1996, The Stillwater complex, in Cawthorn, R.G., ed., Layered Intrusions: Amsterdam, Netherlands, Elsevier, Developments in Petrology 15, p. 441–483, https://doi.org/10.1016/S0167-2894(96)80015-7.
McCallum, I.S., Thurber, D.W., O’Brien, H.E., and Nelson, B.K., 1999, Lead isotopes in sulfides from the Stillwater complex, Montana: Evidence for subsolidus remobilization: Contributions to Mineralogy and Petrology, v. 137, p. 206–219, https://doi.org/10.1007/s004100050546.
McDonald, J.A., 1965, Liquid immiscibility as one factor in chromitite seam formation in the Bushveld igneous complex: Economic Geology, v. 60, p. 1674–1685, https://doi.org/10.2113/gsecongeo.60.8.1674.
McNeil, A.M., and Edgar, A.D., 1987, Sodium-rich metasomatism in the upper mantle: Implications of experiments on the pyrolite-Na2O-rich fluid system at 950 °C, 20 kbar: Geochimica et Cosmochimica Acta, v. 51, p. 2285–2294, https://doi.org/10.1016/0016 -7037(87)90281-X.
Melcher, F., Grum, W., Simon, G., Thalhammer, T.V., and Stumpfl, E.F., 1997, Petrogenesis of the ophiolitic giant chromite deposits of Kempirsai, Kazakhstan: A study of solid and fluid inclusions in chromite: Journal of Petrology, v. 38, p. 1419–1458, https://doi.org/10.1093/petroj/38.10.1419.
Mondal, S.K., and Mathez, E.A., 2007, Origin of the UG2 chromitite layer: Bushveld complex: Journal of Petrology, v. 48, p. 495–510, https://doi.org/10.1093/petrology/egl069.
Morse, S.A., 1979, Reaction constants for En-Fo-Sil equilibria: An adjustment and some applications: American Journal of Science, v. 279, p. 1060–1069, https://doi.org/10.2475/ajs.279.9.1060.
Mukherjee, R., Latypov, R., and Balakrishnan, A., 2017, An intrusive origin of some UG-1 chromitite layers in the Bushveld igneous complex, South Africa: Insights from field relationships: Ore Geology Reviews, v. 90, p. 94–109, https://doi.org/10.1016/j.oregeorev.2017.03.008.
Mungall, J.E., Brenan, J.M., Godel, B., and Gaillard, F., 2015, Transport of metals and sulphur in magmas by flotation of sulphide melt on vapour bubbles: Nature Geoscience, v. 8, p. 216–219, https://doi.org/10.1038/ngeo2373.
Nandedkar, R.H., Ulmer, P., and Müntener, O., 2014, Fractional crystallization of primitive, hydrous arc magmas: An experimental study at 0.7 GPa: Contributions to Mineralogy and Petrology, v. 167, 1015, https://doi.org/10.1007/s00410-014-1015-5.
Naumov, V.B., Kovalenko, V.I., Dorofeeva, V.A., Girnis, A.V., and Yarmolyuk, V.V., 2010, Average compositions of igneous melts from main geodynamic settings according to the investigation of melt inclusions in minerals and quenched glasses of rocks: Geochemistry International, v. 48, p. 1185–1207, https://doi.org/10.1134/S0016702910120049.
Nicholson, D.M., and Mathez, E.A., 1991, Petrogenesis of the Merensky Reef in the Rustenburg section of the Bushveld complex: Contributions to Mineralogy and Petrology, v. 107, p. 293–309, https://doi.org/10.1007/BF00325100.
Novella, D., Frost, D.J., Hauri, E.H., Bureau, H., Raepsaet, C., and Roberge, M., 2014, The distribution of H2O between silicate melt and nominally anhydrous peridotite and the onset of hydrous melting in the deep upper mantle: Earth and Planetary Science Letters, v. 400, p. 1–13, https://doi.org/10.1016/j.epsl.2014.05.006.
O’Driscoll, B., Day, J.M.D., Daly, J.S., Walker, R.J., and McDonough, M.F., 2009, Rhenium-osmium isotopes and platinum-group elements in the Rum layered suite, Scotland: Implications for Cr-spinel seam formation and the composition of the Iceland mantle anomaly: Earth and Planetary Science Letters, v. 286, p. 41–51, https://doi.org/10.1016/j.epsl.2009.06.013.
Page, N.J., 1977, Stillwater Complex, Montana: Rock Succession, Metamorphism and Structure of the Complex and Adjacent Rocks: U.S. Geological Survey Professional Paper 999, 79 p., https://doi.org/10.3133/pp999.
Page, N.J., 1979, Stillwater Complex, Montana: Structure, Mineralogy, and Petrology of the Basal Zone with Emphasis on the Occurrence of Sulfides: U.S. Geological Survey Professional Paper 1038, 78 p., https://pubs.usgs.gov/pp/1038/report.pdf.
Page, N.J., and Zientek, M.L., 1987, Composition of Primary Postcumulus Amphibole and Phlogopite within an Olivine Cumulate in the Stillwater Complex, Montana: U.S. Geological Survey Bulletin 1674A, 35 p., https://pubs.usgs.gov/bul/1674a/report.pdf.
Papike, J.J., Spilde, M.N., Fowler, G.W., and McCallum, I.S., 1995, SIMS studies of planetary cumulates: Orthopyroxene from the Stillwater complex, Montana: The American Mineralogist, v. 80, p. 1208–1221, https://doi.org/10.2138/am-1995-11-1211.
Pebane, M., and Latypov, R., 2017, The significance of magmatic erosion for bifurcation of UG-1 chromitite layers in the Bushveld complex: Ore Geology Reviews, v. 90, p. 65–93, https://doi.org/10.1016/j.oregeorev.2017.02.026.
Peoples, J.W., 1932, The Geology of the Stillwater Igneous Complex, Beartooth Mountains, Montana [Ph.D. thesis]: Princeton, New Jersey, Princeton University, 180 p.
Plank, T., Kelley, K.A., Zimmer, M.M., Hauri, E.H., and Wallace, P.J., 2013, Why do mafic arc magmas contain 4 wt.% water on average?: Earth and Planetary Science Letters, v. 364, p. 168–179, https://doi.org/10.1016/j.epsl.2012.11.044.
Pleše, P., Higgins, M.D., Baker, D.R., Lanzafame, G., Kudrna-Prašek, M., Mancini, L., and Rooyakkers, S.M., 2019, Production and detachment of oxide crystal shells on bubble walls during experimental vesiculation of andesitic magmas: Contributions to Mineralogy and Petrology, v. 174, 21, https://doi.org/10.1007/s00410 -019-1556-8.
Raedeke, L.D., and McCallum, I.S., 1984, Investigations in the Stillwater complex: Part II. Petrology and petrogenesis of the ultramafic series: Journal of Petrology, v. 25, p. 395–420, https://doi.org/10.1093/petrology/25.2.395.
Rollinson, H., Mameri, L., and Barry, T., 2018, Polymineralic inclusions in mantle chromitites from the Oman ophiolite indicate a highly magnesian parental melt: Lithos, v. 310–311, p. 381–391, https://doi.org/10.1016/j.lithos.2018.04.024.
Scowen, P.A.H., Roeder, P.L., and Helz, R.T., 1991, Re-equilibration of chromite within Kilauea Iki lava lake, Hawaii: Contributions to Mineralogy and Petrology, v. 107, p. 8–20, https://doi.org/10.1007/BF00311181.
Sisson, T.W., and Grove, T.L., 1993, Experimental investigations of the role of H2O in calc-alkaline differentiation and subduction zone magmatism: Contributions to Mineralogy and Petrology, v. 113, p. 143–166, https://doi.org/10.1007/BF00283225.
Spandler, C., Mavrogenes, J.A., and Arculus, R., 2005, Origin of chromitites in layered intrusions: Evidence from chromite-hosted melt inclusions from the Stillwater complex: Geology, v. 33, p. 893–896, https://doi.org/10.1130/G21912.1.
Spandler, C., O’Neill, H.S.C., and Kamenetsky, V.S., 2007, Survival times of anomalous melt inclusions from element diffusion in olivine and chromite: Nature, v. 447, no. 7142, p. 303–306, https://doi.org/10.1038/nature05759.
Sparks, R.S.J., Barclay, J., Jaupart, C.P.M.A., Mader, H.M., and Phillips, J.C., 1994, Physical aspects of magma degassing: 1. Experimental and theoretical constraints on vesiculation, in Carroll, M.R., and Holloway, J.R., eds., Volatiles in Magma: Mineralogical Society of America Reviews in Mineralogy and Geochemistry 30, p. 413–445, https://doi.org/10.1515/9781501509674-017.
Stalder, R., and Skogby, H., 2002, Hydrogen incorporation in enstatite: European Journal of Mineralogy, v. 14, p. 1139–1144, https://doi.org/10.1127/0935-1221/2002/0014-1139.
Su, B.X., Robinson, P.T., Chen, C., Xiao, Y., Melcher, F., Bai, Y., Gu, X.Y., Uysal, I., and Lenaz, D., 2020a, The occurrence, origin, and fate of water in chromitites in ophiolites: The American Mineralogist, v. 105, p. 894–903, https://doi.org/10.2138/am-2020-7270.
Su, B.X., Bai, Y., Cui, M.M., Wang, J., Xiao, Y., Lenaz, D., Sakyi, P.A., and Robinson, P.T., 2020b, Petrogenesis of the ultramafic zone of the Stillwater complex in North America: Constraints from mineral chemistry and stable isotopes of Li and O: Contributions to Mineralogy and Petrology, v. 175, 68, https://doi.org/10.1007/s00410-020-01707-y.
Su, B.X., Chen, C., Xiao, Y., Robinson, P.T., Liu, X., Wang, J., Uysal, I., Bai, Y., and Sun, Y., 2021, The critical role of fluid-mediated diffusion in anomalous Fe-Mg-O isotope fractionations in ultramafic rocks of ophiolites: Journal of Geophysical Research: Solid Earth, v. 126, https://doi.org/10.1029/2020JB020632.
Thomson, J.A., 2008, Beneath the Stillwater complex: Petrology and geochemistry of quartz-plagioclase-cordierite (or garnet)-orthopyroxene-biotite ± spinel hornfels, Mountain View area, Montana: The American Mineralogist, v. 93, p. 438–450, https://doi.org/10.2138/am.2008.2572.
Todd, S.G., Keith, D.W., Le Roy, L.W., Schissel, D.J., Mann, E.L., and Irvine, T.N., 1982, The J-M platinum-palladium reef of the Stillwater complex, Montana: I. Stratigraphy and petrology: Economic Geology, v. 77, p. 1454–1480, https://doi.org/10.2113/gsecongeo.77.6.1454.
Turner, A.R., Wolfgram, D., and Barnes, S.J., 1985, Geology of the Stillwater County sector of the J-M reef, including the Minneapolis Adit, in Czamanske, G.K., and Zientek, M.L., eds., Stillwater Complex: Montana Bureau of Mines and Geology Special Publication 92, p. 210–230.
Ulmer, G.C., 1969. Experimental investigations of chromite spinels, in Wilson, H.D.B., ed., Magmatic Ore Deposits: Society of Economic Geologists Monograph 4, pp. 114–131, https://doi.org/10.5382/Mono.04.09.
Veksler, I.V., and Hou, T., 2020, Experimental study on the effects of H2O upon crystallization in the lower and critical zones of the Bushveld complex with an emphasis on chromitite formation: Contributions to Mineralogy and Petrology, v. 175, 85, https://doi.org/10.1007/s00410-020-01733-w.
Wall, C.J., Scoates, J.S., Weis, D., Friedman, R.M., Amini, M., and Meurer, W.P., 2018, The Stillwater complex: Integrating zircon geochronological and geochemical constraints on the age, emplacement history and crystallization of a large, open-system layered intrusion: Journal of Petrology, v. 59, p. 153–190, https://doi.org /10.1093/petrology/egy024.
Wang, C., Liang, Y., and Xu, W., 2021, Formation of amphibole-bearing peridotite and amphibole-bearing pyroxenite through hydrous melt peridotite reaction and in situ crystallization: An experimental study: Journal of Geophysical Research: Solid Earth, v. 126, https://doi.org/10.1029/2020JB019382.
Wang, Z., and Zhang, J., 2015, On the origin of rhythmic layering in layered gabbros: San Francisco, California, American Geophysical Union, Fall Meeting supplement, abstract T43B-2995.
Weis, F.A., Skogby, H., Troll, V.R., Deegan, F.M., and Dahren, B., 2015, Magmatic water contents determined through clinopyroxene: Examples from the Western Canary Islands, Spain: Geochemistry, Geophysics, Geosystems, v. 16, p. 2127–2146, https://doi.org/10.1002/2015GC005800.
Weis, F.A., Lazor, P., and Skogby, H., 2018, Hydrogen analysis in nominally anhydrous minerals by transmission Raman spectroscopy: Physics and Chemistry of Minerals, v. 45, p. 597–607, https://doi.org/10.1007/s00269 -018-0945-2.
Witham, F., Blundy, J., Kohn, S.C., Lesne, P., Dixon, J., Churakov, S.V., and Botcharnikov, R., 2012, SolEx: A model for mixed C-OH-S-Cl-volatile solubilities and exsolved gas compositions in basalt: Computers & Geosciences, v. 45, p. 87–97, https://doi.org/10.1016/j.cageo.2011.09.021.
Xiao, Y., Teng, F.Z., Su, B.X., Hu, Y., Zhou, M.F., Zhu, B., Shi, R.D., Huang, Q.S., Gong, X.H., and He, Y.S., 2016, Iron and magnesium isotopic constraints on the origin of chemical heterogeneity in podiform chromitite from the Luobusa ophiolite, Tibet: Geochemistry, Geophysics, Geosystems, v. 17, p. 940–953, https://doi.org/10.1002/2015GC006223.
Xiong, F., Yang, J., Dilek, Y., and Wang, C., 2017, Nanoscale diopside and spinel exsolution in olivine from dunite of the Tethyan ophiolites, southwestern Turkey: Implications for the multi-stage process: Journal of Nanoscience and Nanotechnology, v. 17, p. 6587–6596, https://doi.org/10.1166/jnn.2017.14506.
Zellmer, G.F., Sakamoto, N., Matsuda, N., Iizuka, Y., Moe-bis, A., and Yurimoto, H., 2016, On progress and rate of the peritectic reaction Fo + SiO2 = En in natural andesitic arc magmas: Geochimica et Cosmochimica Acta, v. 185, p. 383–393, https://doi.org/10.1016/j.gca.2016.01.005.
Zhang, J., Wang, F., Wang, Z., and Song, S., 2014, Water content and deformation microstructure of layered Panzhihua gabbro: Implications for the origin of rhythmic layering: San Francisco, California, American Geophysical Union, Fall Meeting supplement, abstract T31A-4572.
Zhou, M.F., Robinson, P.T., Su, B.X., Gao, J.F., Li, J.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, v. 26, p. 262–283, https://doi.org/10.1016/j.gr.2013.12.011.
Zientek, M.L., 1983, Petrogenesis of the Basal Zone of the Stillwater Complex, Montana [Ph.D. thesis]: Stanford, California, Stanford University, 246 p.
