Abstract
All of the rocks from the Ultramafic series of the Stillwater Complex are enriched in PGE relative to most mafic magmas. Furthermore, the chromite layers are particularly enriched in IPGE (Os, Ir, and Ru) and Rh. This enrichment appears to be a common characteristic of ultramafic rocks from many types of settings, layered intrusions, ophiolites, and zoned complexes. We have carried out a petrological, mineralogical, and geochemical study to assess how the enrichment occurred in the case of the Stillwater Complex and applied our results to the chromite layers of the Bushveld and Great Dyke complexes. The minerals that now host the PGE are laurite and fine-grained intergrowths of pentlandite, millerite, and chalcopyrite. The laurite occurs as inclusions in chromite, and mass balance calculations indicate that it hosts most of the Os, Ir, and Ru. The sulfide minerals occur both as inclusions in chromite and as interstitial grains. The sulfides host much of the Pd and Rh. The IPGE and Rh correlate with Cr but not with S or Se, indicating that these elements were not collected by a sulfide liquid. Palladium, Cu, and Se correlate with each other, but not with S. The low S/Se (<1500) of the whole rock and magnetite rims around the sulfides indicate some S has been lost from the rocks. We conclude that to account for all observations, the IPGE and Rh were originally collected by chromite, and subsequently, small quantities of base metal sulfide liquid was added to the chromite layers from the overlying magma. The IPGE and Rh in the chromite diffused from the chromite into the base metal sulfides and converted some of the sulfides to laurite.
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References
Aird HM, Boudreau AE (2013) High-temperature carbonate minerals in the Stillwater Complex, Montana, USA. Contrib Mineral Petrol 166:1143–1160
Ballhaus C, Ryan CG, Mernagh TP, Green DH (1994) The partitioning of Fe, Ni, Cu, Pt and Au between sulfide, metal, and fluid phases: a pilot study. Geochim Cosmochim Acta 57:811–826
Barnes S-J, Maier WD (2002) Platinum-group element distributions in the Rustenberg Layered Suite of the Bushveld Complex, South Africa. In: Cabri LJ (ed) The geology, geochemistry, mineralogy and mineral beneficiation of platinum-group elements. Can Institute of Mining, Metallurgy and Petroleum Spec. vol. 54. p. 553–580
Barnes S-J, Boyd R, Kornelliussen A, Nilssen L-P, Often M, Pedersen R-B, Robins B (1988) The use of mantle normalization and metal ratios in discriminating the effects of partial melting, crystal fractionation and segregation on platinum group elements, gold, nickel and copper: examples from Norway. In: Prichard HM, Potts PJ, Bowles JFW, Cribb SJ (eds) Geoplatinum 87. Elsevier, London, pp 113–143
Barnes S-J, Savard D, Bédard LP, Maier WD (2009) Selenium and sulfur concentrations in the Bushveld Complex of South Africa and implications for formation of the platinum-group element deposits. Miner Deposita 44:647–663
Barnes S-J, Maier WD, Curl EA (2010) Composition of the marginal rocks and sills of the Rustenburg Layered Suite, Bushveld Complex, South Africa: implications for the formation of the platinum-group element deposits. Econ Geol 105:1491–1511
Bazarkina EF, Pokrovski GS, Hazemann J-L (2014) Structure, stability and geochemical role of palladium chloride complexes in hydrothermal fluids. Geochim Cosmochim Acta 146:107–131
Bédard LP, Barnes S-J (2002) A comparison of N-type semi-planar and coaxial INAA detectors for 33 geochemical reference samples. J Radioanal Nucl Chem 254:485–497
Bédard LP, Savard D, Barnes S-J (2008) Total sulfur concentrations in geological reference materials by elemental infrared analyser. Geostand Geoanal Res 32:203–208
Blaine FA, Linnen RL, Holtz F, Brügmann GE (2005) Platinum solubility in a haplobasaltic melt at 1250 C and 0.2 GPa: the effect of water content and oxygen fugacity. Geochim Cosmochim Acta 69:1265–1273
Borisov A (2005) Crystallization and stability of noble metal alloys in the magmatic process. Geol Ore Deposits 47:469–475
Boudreau A, McCallum I (1989) Investigations of the Stillwater Complex: part V. Apatites as indicators of evolving fluid composition. Contrib Mineral Petrol 102:138–153
Boudreau AE, Mathez EA, McCallum IS (1986) Halogen geochemistry of the Stillwater and Bushveld Complexes: evidence for transport of the platinum-group elements by Cl-rich fluids. J Petrol 27:967–986
Brenan JM, Andrews D (2001) High temperature stability of laurite and Ru-Os-Ir alloy and their role in PGE fractionation in mafic magmas. Can Mineral 39:341–360
Brenan JM, Finnigan CF, McDonough WF, Homolova V (2012) Experimental constraints on the partitioning of Ru, Rh, Ir, Pt and Pd between chromite and silicate melt: the importance of ferric iron. Chem Geol 302:16–32
Butler JR (1966) Geologic evolution of the Beartooth Mountains, Montana and Wyoming. Part 6. Cathedral Peak Area, Montana. Geol Soc Am Bull 77:45–64
Cooper RW (1997) Magmatic unconformities and stratigraphic relations in the Peridotite zone, Stillwater Complex, Montana. Can J Earth Sci 34:407–425
Cooper R, Garuti G, Zaccarini F (2005) Platinum group minerals distribution in chromite layers of the Stillwater complex (Montana, USA). In: Törmänen T, Alapieti TT (eds) 10th International Platinum Symposium. Geological Survey Finland, Oulu, pp 58–61
Crocket JH, Fleet ME (1997) Implications of composition for experimental partitioning of platinum-group elements and gold between sulfide liquid and basalt melt: the significance of nickel content. Geochim Cosmochim Acta 61:4139–4149
Djon MLN, Barnes S-J (2012) Changes in sulfides and platinum-group minerals with the degree of alteration in the Roby, Twilight, and High Grade Zones of the Lac des Iles Complex, Ontario, Canada. Miner Deposita 47:1–22
Ertel W, O’Neill HSC, Sylvester P, Dingwell D (1999) Solubilities of Pt and Rh in a haplobasaltic silicate melt at 1300 C. Geochim Cosmochim Acta 63:2439–2449
Finnigan CS, Brenan JM, Mungall JE, McDonough WF (2008) Experiments and models bearing on the role of chromite as a collector of platinum group minerals by local reduction. J Petrol 49:1647–1665
Fortenfant SS, Günther D, Dingwell DB, Rubie DC (2003) Temperature dependence of Pt and Rh solubilities in a haplobasaltic melt. Geochim Cosmochim Acta 67:123–131
Garuti G, Proenza J, Zaccarini F (2007) Distribution and mineralogy of platinum-group elements in altered chromitites of the Campo Formoso layered intrusion (Bahia State, Brazil): control by magmatic and hydrothermal processes. Mineral Petrol 89:159–188
Godel B (2013) High-resolution X-ray computed tomography and its application to ore deposits: from data acquisition to quantitative three-dimensional measurements with case studies from Ni-Cu-PGE deposits. Econ Geol 108:2005–2019
Godel B, Barnes S-J (2008) Platinum-group elements in sulfide minerals and the whole rock of the J-M Reef (Stillwater complex): implication for the formation of the reef. Chem Geol 248:272–294
González-Jiménez JM, Griffin WL, Gervilla F, Proenza JA, O'Reilly SY, Pearson NJ (2013) Chromitites in ophiolites: How, where, when, why? Part I. A review and new ideas on the origin and significance of platinum-group minerals. Lithos 189:127–139
Gornostayev SS, Laajoki K, Leinonen O (2000) The platinum-group minerals in the Kemi chromite deposit, Finland: a case study of the Elijärvi ore body. In: GEODE-Fennoscandian Shield Workshop, Gällivare-Kiruna, Sweden, vol 6. p 16–22
Hanley JJ, Mungall JE, Pettke T, Spooner ETC, Bray CJ (2008) Fluid and halide melt inclusions of magmatic origin in the Ultramafic and Lower Banded Series, Stillwater Complex, Montana, USA. J Petrol 49:1133–1160
Hiemstra S (1979) The role of collectors in the formation of the platinum deposits in the Bushveld Complex. Can Mineral 17:469–482
Junge M, Oberthür T, Melcher F (2014) Cryptic variation of chromite chemistry, platinum group element and platinum group mineral distribution in the UG-2 chromite: an example from the Karee Mine, Western Bushveld Complex, South Africa. Econ Geol 109:795–810
Kanitpanyacharoen W, Boudreau A (2013) Sulfide-associated mineral assemblages in the Bushveld Complex, South Africa: platinum-group element enrichment by vapor refining by chloride–carbonate fluids. Miner Deposita 48:193–210
Keays RR, Lightfoot PC, Hamlyn PR (2012) Sulfide saturation history of the Stillwater Complex, Montana: chemostratigraphic variation in platinum group elements. Miner Deposita 47:151–173
Kinloch ED (1982) Regional trends in the platinum-group mineralogy of the Critical Zone of the Bushveld Complex, South Africa. Econ Geol 77:1328–1347
Laurenz V, Fonseca RO, Ballhaus C, Jochum KP, Heuser A, Sylvester PJ (2013) The solubility of palladium and ruthenium in picritic melts: 2. The effect of sulfur. Geochim Cosmochim Acta 108:172–183
Li C, Ripley EM, Merino E, Maier WD (2004) Replacement of base metal sulfides by actinolite, epidote, calcite and magnetite in the UG2 and Merensky Reef of the Bushveld Complex, South Africa. Econ Geol 99:173–184
Locmelis M, Pearson NJ, Barnes SJ, Fiorentini ML (2011) Ruthenium in komatiitic chromite. Geochim Cosmochim Acta 75:3645–3661
Maier WD, Prichard HM, Barnes SJ, Fisher PC (1999) Compositional variation of laurite at Union Section in the Western Bushveld Complex. S Afr J Geol 102:286–292
Maier WD, Barnes S-J, Groves D (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. Miner Deposita 48:1–56
McCallum IS (2002). The Stillwater Complex: a review of the geology. In: 9th International Platinum Symposium, Geology and Guide Stillwater Complex, Montana, USA, Billings. p 21–25
McCallum IS, Raedeke LD, Mathez ED (1980) Investigations of the Stillwater Complex: Part I. Stratigraphy and structure of the Banded zone. Am J Sci 280:59–87
McDonough WF, Sun S-S (1995) The composition of the Earth. Chem Geol 120:223–253
Merkle RKW (1992) Platinum-group minerals in the middle group of chromitite layers at Marikana, western Bushveld Complex: indications for collection mechanisms and postmagmatic modification. Can J Earth Sci 29:209–221
Mungall J, Brenan J (2014) Partitioning of platinum-group elements and Au between sulfide liquid and basalt and the origins of mantle-crust fractionation of the chalcophile elements. Geochim Cosmochim Acta 125:265–289
Naldrett AJ (2011) Fundamentals of magmatic sulfide deposit. In: Li C, Ripley EM (eds) Magmatic Ni-Cu and PGE deposits: geology, geochemistry, and genesis, reviews in economic geology, vol 17. Society of Economic Geologists, Lillteton, pp 1–50
Naldrett A, Lehmann J (1988) Spinel non-stoichiometry as the explanation for Ni-, Cu-and PGE-enriched sulphides in chromitites. In: Prichard HM, Potts PJ, Bowles JFW, Cribb SJ (eds) Geoplatinum 87. Elsevier, London, pp 93–109
Naldrett AJ, Kinnaird J, Wilson A, Yudovskaya M, McQuade S, Chunnett G, Stanley C (2009) Chromite composition and PGE content of Bushveld chromitites: part 1—the Lower and Middle Groups. Appl Earth Sci: Trans Inst Min Metall Sect B 118:131–161
Oberthür T (2002). Platinum-group element mineralization of the Great Dyke, Zimbabwe. In: Cabri LJ (ed) The geology, geochemistry, mineralogy and mineral beneficiation of platinum-group elements. Can Inst Min, Metall Petrol Special vol 54. p 483-506
Ohnenstetter D, Watkinson DH, Jones PC, Talkington RW (1986) Cryptic compositional variation in laurite and enclosing chromite from the Bird River Sill, Manitoba. Econ Geol 81:1159–1168
Page NJ (1971) Sulfide minerals in the G and H chromitite zones of the Stillwater Complex, Montana. U.S Geological Survey Professional Paper 694: 20 p
Page NJ (1977) Stillwater Complex, Montana: rock succession, metamorphism and structure of the complex and adjacent rocks. U.S Geological Survey Professional Paper 999: 79 p
Pagé P, Barnes S-J (2013) Improved in-situ determination of PGE concentration of chromite by LA-ICP-MS: Towards a better understanding. In: Mineral Deposit research for a high-tech world, 12th Biennial SGA Meeting, Uppsala, p 1050–1053
Pagé P, Barnes S-J, Bédard JH, Zientek ML (2012) In situ determination of Os, Ir, and Ru in chromites formed from komatiite, tholeiite and boninite magmas: implications for chromite control of Os, Ir and Ru during partial melting and crystal fractionation. Chem Geol 302:3–15
Park J-W, Campbell IH, Eggins SM (2012) Enrichment of Rh, Ru, Ir and Os in Cr spinels from oxidized magmas: evidence from the Ambae volcano, Vanuatu. Geochim Cosmochim Acta 78:28–50
Patten C, Barnes S-J, Mathez EA (2012) Textural variations in MORB sulfide droplets due to differences in crystallization history. Can Mineral 50:675–692
Patten C, Barnes S-J, Mathez EA, Jenner FE (2013) Partition coefficients of chalcophile elements between sulfide and silicate melts and the early crystallization history of sulfide liquid: LA-ICP-MS analysis of MORB sulfide droplets. Chem Geol 358:170–188
Peach CL, Mathez EA, Keays RR (1990) Sulfide melt-silicate melt distribution coefficients for noble metals and other chalcophile elements as deduced from MORB: implications for partial melting. Geochim Cosmochim Acta 54:3379–3389
Peregoedova A, Barnes S-J, Baker DR (2006) An experimental study of mass transfer of platinum-group elements, gold, nickel and copper in sulfur-dominated vapor at magmatic temperatures. Chem Geol 235:59–75
Potts PJ (1987) A handbook of silicate rock analysis. Blackie Glasgow
Prichard HM, Neary C, Fisher PC, O’Hara M (2008) PGE-rich podiform chromitites in the Al ‘Ays Ophiolite Complex, Saudi Arabia: an example of critical mantle melting to extract and concentrate PGE. Econ Geol 103:1507–1529
Prichard H M, Barnes S-J, Fisher P C, Pagé P, Zientek M (2014) PGM in the Stillwater chromitites and implications for the magmatic processes that formed the ultramafic part of the Stillwater Complex. XII International Pt Symposium, Yekaterinburg, Russia
Righter K, Campbell AJ, Humayun M, Hervig RL (2004) Partitioning of Ru, Rh, Pd, Ir and Au between Cr-bearing spinel, olivine, pyroxene and silicate melts. Geochim Cosmochim Acta 68:867–880
Savard D, Bédard LP, Barnes S-J (2006) TCF selenium preconcentration in geological materials for determination at sub micro-gm with INAA (Se TCF/INAA). Talanta 70:566–571
Savard D, Barnes SJ, Meisel T (2010) Comparison between nickel-sulfur fire assay Te co-precipitation and isotope dilution with high-pressure asher acid digestion for the determination of platinum-group elements, rhenium and gold. Geostand Geoanal Res 34:281–291
Scoon RN, Teigler B (1994) Platinum-group element mineralization in the critical zone of the Western Bushveld Complex: 1. Sulfide poor chromitites below the UG2. Econ Geol 89:1094–1121
Smith JW, Holwell DA, McDonald I (2014) Precious and base metal geochemistry and mineralogy of the Grasvally Norite–Pyroxenite–Anorthosite (GNPA) member, northern Bushveld Complex, South Africa: implications for a multistage emplacement. Miner Deposita 49:667–692
Tagirov BR, Baranova NN, Zotov AV, Akinfiev NN, Polotnyanko NA, Shikina ND, Koroleva LA, Shvarov YV, Bastrakov EN (2013) The speciation and transport of palladium in hydrothermal fluids. Experimental modeling and thermodynamic constraints. Geochim Cosmochim Acta 117:348–373
Talkington RW, Lipin BR (1986) Platinum-group minerals in chromite seams of the Stillwater Complex, Montana. Econ Geol 81:1179–1186
Thomson JA (2008) Beneath the Stillwater Complex: Petrology and geochemistry of quartz-plagioclase-cordierite (or garnet)-orthopyroxene-biotite ± spinel hornfels, Mountain View area, Montana. Am Mineral 93:438–450
Todd SG, Keith DW, LeRoy LW, Shissel DJ, Mann EL, Irvine TN (1982) The J-M platinum-palladium Reef of the Stillwater Complex, Montana: I. Stratigraphy and petrology. Econ Geol 77:1454–1480
Von Gruenewaldt G, Hatton CJ, Merkle RKW, Gain SB (1986) Platinum-group element-chromite associations in the Bushveld Complex. Econ Geol 81:1067–1079
Wall CJ, Scoates JS, Friedman RM, Weis DA, Meurer W (2010) Baddeleyite-Zircon Relationships in cumulates of the Archean Stillwater Complex: evidence from U-Pb geochronology and Hf isotope systematics. AGU Fall Meeting Abstracts p 2309
Waters C, Boudreau AE (1996) A re-evaluation of crystal-size distributions in chromite cumulates. Am Minerol 81:1452–1459
Webb PC, Thompson M, Potts PJ, Bédard LP (2006) GEOPT18—an international proficiency test for analytical geochemistry laboratories—report on round 18/Jan 2006 (Quartz diorite, KPT-1). International Association of Geoanalysts. www.geoanalyst.org/geopt/GeoPT18Report.pdf accessed 12 June 2014
Wooden JL, Czamanske GK, Zientek ML (1991) A lead isotopic study of the Stillwater Complex Montana; constraints on crustal contamination and source regions. Contrib Mineral Petrol 107:80–93
Zientek ML (2012) Magmatic ore deposits in layered intrusions—descriptive model for reef-type PGE and contact-type Cu-Ni-PGE deposits. U.S Geological Survey Open File 2012–1010. p 48
Zientek ML, Foose MP, Mei L (1986) Palladium, platinum, and rhodium contents of rocks near the lower margin of the Stillwater Complex, Montana. Econ Geol 81:1169–1178
Zientek ML, Cooper RW, Corson SR, Geraghty EP (2002) Platinum-group element mineralization in the Stillwater Complex, Montana. In: Cabri, LJ (ed) Geology, geochemistry, mineralogy and mineral beneficiation of platinum group element. Can Inst Min Metall Petrol Spec vol 54. p 459–481
Acknowledgments
We would like to thank Mr. Dany Savard and Ms. Sahdi Mehdi for their careful analytical work. The reviewers, Prof. Alan Boudreau Dr. Steve Barnes and Dr. M. Fiorentini are thanked for their detailed reviews. This work was funded by a Canadian Natural Science and Engineering Research Council Discovery Grant to SJB (17313) and a Canada Research Chair program grant to SJB (215503).
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Barnes, SJ., Pagé, P., Prichard, H.M. et al. 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. Miner Deposita 51, 25–47 (2016). https://doi.org/10.1007/s00126-015-0587-y
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DOI: https://doi.org/10.1007/s00126-015-0587-y