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Platinum-group element remobilization and concentration in the Cliff chromitites of the Shetland Ophiolite Complex, Scotland

Published online by Cambridge University Press:  12 April 2018

Brian O'Driscoll ,
Russell Garwood ,
James M. D. Day  and
Roy Wogelius
Brian O'Driscoll*
Affiliation:
School of Earth and Environmental Sciences, Oxford Road, University of Manchester M13 9PL, UK
Russell Garwood
Affiliation:
School of Earth and Environmental Sciences, Oxford Road, University of Manchester M13 9PL, UK Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK
James M. D. Day
Affiliation:
Geosciences Research Division, Scripps Institution of Oceanography, UCSD, La Jolla, CA 92093-0244, USA
Roy Wogelius
Affiliation:
School of Earth and Environmental Sciences, Oxford Road, University of Manchester M13 9PL, UK
*
*E-mail: [email protected]
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Abstract

The ~492 Ma Shetland Ophiolite Complex contains an extensive mantle section, within which numerous podiform chromitite bodies formed during melt percolation in a supra-subduction zone setting. One of the Shetland ophiolite chromitite localities has an unusual style of platinum-group element (PGE) mineralization. Specifically, the Cliff chromitite suite has relatively high (>250 ppm) Pt plus Pd, compared to other chromitites in the Shetland Ophiolite Complex. In this study, we apply petrographic observation, mineral chemistry and novel X-ray microtomography data to elucidate the petrogenesis of PGE-bearing phases at Cliff. The combined datasets reveal that the PGE at Cliff have probably been fractionated by an As-rich fluid, concentrating Pt and Ir into visible (0.1–1 µm) platinum-group minerals (PGM) such as sperrylite and irarsite, respectively. The high (>1 ppm) bulk-rock concentrations of the other PGE (e.g. Os) in the Cliff chromitites suggests the presence of abundant fine-grained unidentified PGM in the serpentinized groundmass. The spatial association of arsenide phases and PGM with alteration rims on Cr-spinel grains suggests that the high Pt and Pd abundances at Cliff result from a late-stage low-temperature (e.g. 200–300°C) hydrothermal event. This conclusion highlights the potential effects that secondary alteration processes can have on modifying and upgrading the tenor of PGE deposits.

Keywords

platinum-group elementschromititesShetland Ophiolite Complex
Type
Article
Information
Mineralogical Magazine , Volume 82 , Special Issue 3: Special Issue dedicated to the work and memory of Professor Hazel M. Prichard (1954–2017) , June 2018 , pp. 471 - 490
Copyright
Copyright © Mineralogical Society of Great Britain and Ireland 2018 

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Footnotes

This paper is published as part of a thematic set in memory of Professor Hazel M. Prichard

Associate Editor: John Bowles

References

Ahmed, A.H. and Arai, S. (2002) Unexpectedly high-PGE chromitite from the deeper mantle section of the northern Oman ophiolite and its tectonic implications. Contributions to Mineralogy and Petrology, 143, 263–278.Google Scholar
Ahmed, A.H., Arai, S., Abdel-Aziz, Y.M., Ikenne, M. and Rahimi, A. (2009 a) Platinum-group elements distribution and spinel composition in podiform chromitites and associated rocks from the upper mantle section of the Neoproterozoic Bou Azzer ophiolite, Anti-Atlas, Morocco. Journal of African Earth Sciences, 55, 92–104.CrossRefGoogle Scholar
Ahmed, A.H., Arai, S. and Ikenne, M. (2009 b) Mineralogy and Paragenesis of the Co-Ni arsenide ores of Bou Azzer, Anti-Atlas, Morocco. Economic Geology, 104, 249–266.Google Scholar
Barnes, S.J. (2000) Chromite in Komatiites II. Modification during greenschist to mid-amphibolite facies metamorphism. Journal of Petrology, 41, 387–409.Google Scholar
Barnes, S.J. and Roeder, P.L. (2001) The range of spinel compositions in terrestrial mafic and ultramafic rocks. Journal of Petrology, 42, 2279–2302.Google Scholar
Brenan, J.M. and Rose, L.A. (2002) Experimental constraints on the wetting of chromite by sulfide liquid. The Canadian Mineralogist, 40, 1113–1126.Google Scholar
Büchl, A., Brügmann, G.E. and Batanova, V.G (2004) Formation of podiform chromitite deposits: implications from PGE abundances and Os isotopic compositions of chromites from the Troodos complex, Cyprus. Chemical Geology, 208, 217–232.Google Scholar
Chew, D.M., Daly, J.S., Magna, T., Pagé, L.M., Kirkland, C.L., Whitehouse, M.J. and Lam, R. (2010) Timing of ophiolite obduction in the Grampian orogen. Geological Society of America Bulletin, 122, 1787–1799.Google Scholar
Coggon, J.A., Nowell, G.M., Pearson, D.G., Lorand, J.-P., Oberthür, T. and Parman, S.W. (2011) The 190Pt-186Os decay system applied to dating platinum-group element mineralization of the Bushveld Complex, South Africa. Chemical Geology, 302–303, 48–60.Google Scholar
Crowley, Q.G. and Strachan, R.A. (2015) U-Pb constraints on obduction initiation of the Unst Ophiolite: an oceanic core complex in the Scottish Caledonides? Journal of the Geological Society, London, 172, 279–282.Google Scholar
Cutts, K.A., Hand, M., Kelsey, D.E. and Strachan, R.A. (2011) P-T constraints and timing of Barrovian metamorphism in the Shetland Islands, Scottish Caledonides: implications for the structural setting of the Unst ophiolite. Journal of the Geological Society, London, 168, 1265–1284.Google Scholar
Dare, S.A.S., Barnes, S.-J., Prichard, H.M. and Fisher, P.C. (2010) The timing and formation of platinum-group minerals from the Creighton Ni-Cu-platinum-group element sulfide deposit, Sudbury, Canada: Early crystallization of PGE-rich sulfarsenides. Economic Geology, 105, 1071–1096.Google Scholar
Day, J.M.D., O'Driscoll, B., Strachan, R.A., Daly, J.S. and Walker, R.J. (2017) Identification of mantle peridotite as a possible Iapetan ophiolite sliver in south Shetland, Scottish Caledonides. Journal of the Geological Society, London, 174(1), 88–92.Google Scholar
Derbyshire, E.J., O'Driscoll, B., Lenaz, D., Gertisser, R. and Kronz, A. (2013) Compositionally heterogeneous podiform chromitite in the Shetland Ophiolite Complex (Scotland): implications for chromitite petrogenesis and late-stage alteration in the upper mantle portion of a supra-subduction zone ophiolite. Lithos, 162–163, 279–300.Google Scholar
Fleet, M.E., Chryssoulis, S.L., Stone, W.E. and Weisener, G. (1993) Partitioning of platinum-group elements and Au in the Fe-Ni-Cu-S system: Experiments on the fractional crystallization of sulfide melt. Contributions to Mineralogy and Petrology, 115, 36–44.CrossRefGoogle Scholar
Flinn, D. (2001) The basic rocks of the Shetland Ophiolite Complex and their bearing on its genesis. Scottish Journal of Geology, 37, 79–96.CrossRefGoogle Scholar
Flinn, D., Miller, J.A. and Roddom, D. (1991) The age of the Norwick hornblendic schists of Unst and Fetlar and the obduction of the Shetland ophiolite. Scottish Journal of Geology, 27, 11–19.CrossRefGoogle Scholar
Garwood, R.J. and Dunlop, J.A. (2014) The walking dead: Blender as a tool for palaeontologists with a case study on extinct arachnids. Journal of Palaeontology, 88(4), 735–746.Google Scholar
Garwood, R.J. and Sutton, M.D. (2010) X-ray micro-tomography of Carboniferous stem-Dictyoptera: New insights into early insects. Biology Letters, 6, 699–702.CrossRefGoogle ScholarPubMed
Gauthier, M., Corrivaux, L., Trottier, L.J., Cabri, J., Gilles Laflamme, J.H. and Bergeron, M. (1990) Mineralium Deposita, 25, 169–178.Google Scholar
Godel, B. (2013) High resolution X-ray computed tomography and its application to ore deposits: case studies from Ni-Cu-PGE deposits. Economic Geology, 108, 2005–2019.Google Scholar
Godel, B. (2015) Platinum-group element deposits in layered intrusions: recent advances in the understanding of the ore forming processes. Pp. 379–432 in: Layered Intrusions (Charlier, B., Namur, O., Latypov, R. and Tegner, C., editors). Springer, The Netherlands.Google Scholar
Godel, B. and Barnes, S.-J. (2008) Image analysis and composition of platinum-group minerals in the J-M Reef, Stillwater Complex. Economic Geology, 103, 637–651.CrossRefGoogle Scholar
Godel, B., Barnes, S.J., Barnes, S.-J. and Maier, W.D. (2010) Platinum ore in 3D: Insights from high-resolution X-ray computed tomography. Geology, 38(12), 1127–1130.Google Scholar
Godel, B., Gonzalez-Alvarez, I., Barnes, S.J., Barnes, S.-J., Parker, P. and Day, J. (2012) Sulfides and sulfarsenides from the Rosie Nickel Prospect, Duketon Greenstone Belt, Western Australia. Economic Geology, 107, 275–294.Google Scholar
González-Jiménez, J.M., Kerestedjian, T., Proenza, J.A. and Gervilla, F. (2009) Metamorphism of chromite ores from the Dobromirtsi Ultramafic Massif, Rhodope Mountains (SE Bulgaria). Geologica Acta, 7, 413–429.Google Scholar
González-Jiménez, J.M., Griffin, W.L., Gervilla, F., Proenza, J.A., O'Reilly, S.Y. and Pearson, N.J. (2014 a) Chromitites in ophiolites: how, where, when, why? Part I. Origin and significance of platinum-group minerals. Lithos, 189, 127–139.CrossRefGoogle Scholar
González-Jiménez, J.M., Griffin, W.L., Proenza, J.A., Gervilla, F., O'Reilly, S.Y., Akbulut, M., Pearson, N.J. and Arai, S. (2014 b) Chromitites in ophiolites: how, where, when, why? Part II. The crystallisation of chromitites. Lithos, 189, 140–158.Google Scholar
Hanley, J.J. (2005) The aqueous geochemistry of the platinum-group elements (PGE) in surficial, low-T hydrothermal and high-T magmatic hydrothermal environments. Pp. 35–56 in: Exploration for Platinum-Group Element Deposits (Mungall, J.E., editor). Mineral Association of Canada, Quebec, Canada.Google Scholar
Hanley, J.J. (2007) The role of arsenic-rich melts and mineral phases in the development of high grade Pt-Pd mineralization within komatiite-associated magmatic Ni–Cu sulfide horizons at Dundonald Beach South, Abitibi Subprovince, Ontario, Canada. Economic Geology, 102, 305–317.Google Scholar
Helmy, H.M. and Bragagini, A. (2017) Platinum-group elements fractionation by selective complexing, the Os, Ir, Ru, Rh-arsenide-sulfide systems above 1020°C. Geochimica et Cosmochimica Acta, 216, 169–183.CrossRefGoogle Scholar
Helmy, H.M., Ballhaus, C., Fonseca, R.O.C. and Nagel, T.J. (2013) Fractionation of platinum, palladium, nickel, and copper in sulfide-arsenide systems at magmatic temperature. Contributions to Mineralogy and Petrology, 166, 1725–1737.Google Scholar
Holwell, D.A. and McDonald, I. (2010) A review of the behaviour of platinum group elements within natural magmatic sulfide ore systems. Platinum Metals Review, 54, 26–36.Google Scholar
Irvine, T.N. (1977) Origin of chromitite layers in the Muskox intrusion and other stratiform intrusions: A new interpretation. Geology, 5, 273–277.Google Scholar
Karup-Møller, S., Mackovicky, E. and Barnes, S.-J. (2008) The metal-rich portions of the phase system Cu–Fe–Pd–S at 1000°C, 900°C and 725°C: implications for mineralization in the Skaergaard intrusion. Mineralogical Magazine, 72, 941–951.CrossRefGoogle Scholar
Ketcham, R.A. and Carlson, W.D. (2001) Acquisition, optimization and interpretation of X-ray computed tomographic imagery: applications to the geosciences. Computers and Geosciences, 27, 381–400.Google Scholar
Kiefer, S., Majzlan, J., Chovan, M. and Števko, M. (2017) Mineral compositions and phase relations of the complex sulfarsenides and arsenides from Dobšiná (Western Carpathians, Slovakia). Ore Geology Reviews, 89, 894–908.CrossRefGoogle Scholar
Kimball, K. (1990) Effects of hydrothermal alteration on the composition of chromian spinels. Contributions to Mineral Petrology, 105, 337–346.CrossRefGoogle Scholar
Latypov, R., O'Driscoll, B. and Lavrenchuk, A. (2013) Towards a model for an in situ origin for PGE reefs in layered intrusions: insights from the chromitite seams of the Rum Eastern Layered Intrusion, Scotland. Contributions to Mineral Petrology, 166, 309–327.Google Scholar
Le Vaillant, M., Barnes, S.J., Fiorentini, M.L., Miller, J., McCuaig, T.C. and Muccilli, P. (2015) A hydrothermal Ni-As-PGE geochemical halo around the Miitel komatiite-hosted nickel sulfide deposit, Yilgarn Craton, Western Australia. Economic Geology, 110, 505–530.CrossRefGoogle Scholar
Limaye, A. (2012) Drishti: a volume exploration and presentation tool. Developments in X-Ray Tomography VIII, SPIE Proceedings, 8506. International Society for Optics and Photonics, pp. 85060X–85060X.Google Scholar
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, 38, 1419–1458.CrossRefGoogle Scholar
Mellini, M., Rumori, C. and Viti, C. (2005) Hydrothermally reset magmatic spinels in retrograde serpentinites: formation of ‘ferritchromit’ rims and chlorite aureoles. Contributions to Mineralogy and Petrology, 149, 266–275.CrossRefGoogle Scholar
Merlini, A., Grieco, G. and Diella, V. (2009) Ferritchromit and chromium-chlorite formation in melange-hosted Kalkan chromitite (Southern Urals, Russia). American Mineralogist, 94, 1459–1467.Google Scholar
Mungall, J.E. and Brenan, J.M. (2014) Partitioning of platinum-group elements and Au between sulfide liquid and basalt and the origins of mantle–crust fractionation of the chalcophile elements. Geochimica et Cosmochimica Acta, 125, 265–289.Google Scholar
Naldrett, A.J. and Duke, J.M. (1980) Platinum metals in magmatic sulfide ores. Science, 208, 1417–1424.Google Scholar
O'Driscoll, B. and González-Jiménez, J.M. (2016) Petrogenesis of the platinum-group minerals. Pp. 489–578 in: Highly Siderophile and Strongly Chalcophile Elements in High-Temperature Geochemistry and Cosmochemistry, (Harvey, J. and Day, J.M.D., editors). Reviews in Mineralogy & Geochemistry, 81. Mineralogical Society of America and the Geochemical Society, Chantilly, Virginia, USA.Google Scholar
O'Driscoll, B., Day, J.M.D., Daly, J.S., Walker, R.J. and McDonough, W.F. (2009) Rhenium-osmium isotope 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, 286, 41–51.CrossRefGoogle Scholar
O'Driscoll, B., Day, J.M.D., Walker, R.J., Daly, J.S., McDonough, W.F. and Piccoli, P.M. (2012) Chemical heterogeneity in the upper mantle recorded by peridotites and chromitites from the Shetland Ophiolite Complex, Scotland. Earth and Planetary Science Letters, 333–334, 226–237.Google Scholar
O'Driscoll, B., Walker, R.J., Day, J.M.D., Ash, R.D. and Daly, J.S. (2015) Generations of melt extraction, melt-rock interaction and high-temperature metasomatism preserved in peridotites of the ~497 Ma Leka Ophiolite Complex, Norway. Journal of Petrology, 56(9), 1797–1828.Google Scholar
Oshin, I.O. and Crocket, J.H. (1986) Noble metals in the Thetford Mines ophiolites, Quebec, Canada. II. Distribution of gold, silver, iridium, platinum and palladium in the Lac de l'Est volcano-sedimentary section. Economic Geology, 81, 931–945.Google Scholar
Page, N.J. and Talkington, R.W. (1984) Palladium, platinum, rhodium, ruthenium, and iridium in peridotites and chromites from ophiolite complexes in Newfoundland. Canadian Mineralogist, 22, 137–149.Google Scholar
Pina, R., Gervilla, F., Barnes, S.-J., Ortega, L. and Lunar, R. (2013) Partition coefficients of platinum group and chalcophile elements between arsenide and sulfide phases as determined in the Beni Bousera Cr-Ni mineralization (North Morocco). Economic Geology, 108, 935–951.Google Scholar
Prichard, H.M. (1985) The Shetland Ophiolite. Pp. 1173–1184 in: The Caledonide Orogen – Scandinavia and Related Areas (Gee, D.G. and Sturt, B.A., editors). Wiley, New York.Google Scholar
Prichard, H.M. and Lord, R. (1993) An overview of the PGE concentrations in the Shetland Ophiolite Complex. Pp. 273–294 in: Magmatic Processes and Plate Tectonics (Prichard, H.M., Alabaster, T., Harris, N.B.W. and Neary, C.R., editors). Geological Society of London Special Publications, 76.Google Scholar
Prichard, H. and Tarkian, M. (1988) Platinum and palladium minerals from two PGE-rich localities in the Shetland Ophiolite Complex. The Canadian Mineralogist, 26, 979–990.Google Scholar
Prichard, H.M., Ixer, R., Lord, R.A., Maynard, J. and Williams, N. (1994) Assemblages of platinum-group minerals and sulfides in silicate lithologies and chromite-rich rocks within the Shetland Ophiolite. The Canadian Mineralogist, 32, 271–294.Google Scholar
Prichard, H.M., Fisher, P.C., McDonald, I., Knight, R.D., Sharp, D.R. and Williams, J.P. (2013) The distribution of PGE and the role of Arsenic as a collector of PGE in the Spotted Quoll nickel ore deposit in the Forrestania Greenstone Belt, Western Australia. Economic Geology, 108, 1903–1921.Google Scholar
Prichard, H.M., Barnes, S.J., Godel, B., Halfpenny, A., Neary, C.R. and Fisher, P.C. (2015) The structure of and origin of nodular chromite from the Troodos ophiolite, Cyprus, revealed using high-resolution X-ray computed tomography and electron backscatter diffraction. Lithos, 218–219, 87–98.Google Scholar
Prichard, H.M., Barnes, S.J., Dale, C.W., Godel, B., Fisher, P.C. and Nowell, G.M. (2017) Paragenesis of multiple platinum-group mineral populations in Shetland ophiolite chromitite: 3D X-ray tomography and in situ Os isotopes. Geochimica et Cosmochimica Acta, 216, 314–334.Google Scholar
Schouwstra, R.P., Kinloch, E.D. and Lee, C.A. (2000) A short geological review of the Bushveld Complex. Platinum Metals Review, 44, 33–39.Google Scholar
Spray, J.G. and Dunning, G.R. (1991) A U/Pb age for the Shetland Islands oceanic fragment, Scottish Caledonides: evidence from anatectic plagiogranites in ‘layer 3’ shear zones. Geological Magazine, 128, 667–671.Google Scholar
Sutton, M.D., Garwood, R.J., Siveter, D.J. and Siveter, D.J. (2012) Spiers and VAXML; A software toolkit for tomographic visualisation, and a format for virtual specimen interchange. Palaeontologia Electronica, 15(2), T4, 14 pp.Google Scholar
Tarkian, M. and Prichard, H.M. (1987) Irarsite-hollingworthite solid-solution series and other associated Ru-, Os-, Ir- and Rh-bearing PGM's from the Shetland ophiolite complex. Mineralium Deposita, 22, 178–184.Google Scholar
Titarenko, V., Bradley, R., Martin, C., Withers, P.J. and Titarenko, S. (2010) Regularization methods for inverse problems in x-ray tomography. Developments in X-Ray Tomography VII, Proceedings, 7804, 40Z.Google Scholar
Wood, M. (2003) Arsenic in Igneous Systems: An Experimental Investigation. Unpublished BASc thesis, University of Toronto, Ontario, Canada.Google Scholar
Yund, R.A. (1961) Phase relations in the system Ni-As. Economic Geology, 56, 1273–1296.Google Scholar