Abstract
Magmatic differentiation and/or assimilation and related segregation of immiscible sulfide liquid are generally believed to be critical processes in the formation of the majority of orthomagmatic Ni sulfide deposits. In recent years, a new class of Ni sulfide deposits formed by metasomatic and/or hydrothermal modification of peridotites has been recognized. The serpentinite-hosted Avebury Ni sulfide deposit (Tasmania, Australia), the largest known non-magmatic sulfide deposit, provides an unprecedented opportunity to understand sources of metals and fluids responsible for this style of economic mineralization. Our study shows that serpentinization of the Ni-bearing olivine in the Cambrian peridotites of the McIvor Hill complex was followed by metasomatic transformation assisted by heat and fluids supplied by the nearby Late Devonian granite intrusion. The role of the above in the formation of an economic concentration of Ni sulfides is supported by (1) abundant Ni-Fe alloys and sulfides associated with serpentinization of peridotitic olivine, (2) metasomatic olivine containing inclusions of serpentine and metalliferous brines, and (3) the Late Devonian age of the Ni sulfide deposit. The Avebury meta-somatic olivine is Ni-depleted and enriched in Mn relative to olivine of similar Fo content in nearby unmineralized peridotites, and to olivine in subduction-related mafic magmas generally. The unusual minor element chemistry of olivine is matched by a unique set of olivine-hosted multiphase inclusions composed of fibrous Mg-silicates and various Na-, K-, Fe-, Ca-, Mn-, and Ba-bearing chlorides/ hydrochlorides, sulfides, arsenides magnetite, REE minerals, and Fe-Ni alloys.
Peridotite whole-rock Sr-Nd-Pb isotope data and U-Pb dating of metasomatic titanite support earlier suggestions that Ni mineralization is temporally and genetically related with the intrusion of the nearby 360 Ma Heemskirk Granite. It appears that the multiphase inclusions in metasomatic olivine demonstrate chemical signatures of both in situ serpentinites (entrapped alloys, sulfides, arsenides, and magnetite) and distal fluids (enrichment in Pb, Bi, Sn, Sb, Sr, Ba, Rb, Cs, and Ce).
We propose that magmatic olivine in large ultramafic bodies provides almost infinite Ni to replacive serpentinites and constitutes a major reservoir of disseminated Ni mineralization. In the case of Ave-bury Ni was locally redistributed from olivine in the Cambrian peridotites to mainly Fe-Ni alloys and sulfides during serpentinization in the early Paleozoic. In the Devonian reheating and interaction with a granitic fluid in the contact aureole of the Heemskirk Granite led to de-serpentinization and formation of metasomatic high-Mn, low-Ni olivine with inclusions of serpentine and entrapped alloys, sulfides, arsenides, and magnetite, and metalliferous brines rich in “granitic” elements. Nickel released from serpentinite in this process was re-deposited near the margins of the peridotite to form the Avebury Ni orebody. Our model of serpentinization-related release of Ni from magmatic olivine, in situ precipitation of metallic, sulfide, and arsenide Ni-minerals, and their redistribution and recrystallization in hydrothermal conditions represents an alternative to Ni remobilization from magmatic sulfides.
Special collection papers can be found online at http://www.minsocam.org/MSA/AmMin/special-collections.html.
Acknowledgments
Marcel Guillong and Sarah Gilbert are thanked for assistance with laser ablation ICP-MS analyses. MMG (Minerals and Metals Group) provided access to drill-core and geological materials and supported this publication. Constructive comments by an anonymous reviewer and Jim Webster and editorial handling by Julie Roberge are greatly appreciated. This study was funded by the ARC Centre of Excellence in Ore Deposits to A.V.L. and J.G.F. and the ARC Discovery Grant to V.S.K.
References
Auclair, M., Gauthier, M., Trottier, J., Jebrak, M., and Chartrand, F. (1993) Mineralogy, geochemistry, and paragenesis of the Eastern Metals serpentinite-associated Ni-CuZn deposit, Quebec Appalachians. Economic Geology, 88, 123–138.10.2113/gsecongeo.88.1.123Search in Google Scholar
Berry, R.F., and Crawford, A.J. (1988) The tectonic significance of Cambrian allochthonous mafic-ultramafic complexes in Tasmania. Australian Journal of Earth Sciences, 35, 523–533.10.1080/08120098808729467Search in Google Scholar
Black, L.P., McClenaghan, M.P., Korsch, R.J., Everard, J.L., and Foudoulis, C. (2005) Significance of Devonian-Carboniferous igneous activity in Tasmania as derived from U-Pb SHRIMP dating of zircon. Australian Journal of Earth Sciences, 52, 807–829.10.1080/08120090500304232Search in Google Scholar
Black, L.P., Everard, J.L., McClenaghan, M.P., Korsch, R.J., Calver, C.R., Fioretti, A.M., Brown, A.V., and Foudoulis, C. (2010) Controls on Devonian-Carboniferous magmatism in Tasmania, based on inherited zircon age patterns, Sr, Nd and Pb isotopes, and major and trace element geochemistry. Australian Journal of Earth Sciences, 57, 933–968.10.1080/08120099.2010.509407Search in Google Scholar
Butt, C.R.M., and Cluzel, D. (2013) Nickel laterite ore deposits: Weathered serpentinites. Elements, 9, 123–128.10.2113/gselements.9.2.123Search in Google Scholar
Callaghan, T., and Green, G.R. (2014) Avebury nickel deposits. In K.D. Corbett, P.G. Quilty, and C.R. Calver, Eds., Geological Evolution of Tasmania, Special Publication 24, p. 357–361. Geological Society of Australia.Search in Google Scholar
Chamberlain, J.A. (1966) Heazlewoodite and awaruite in serpentinites of the Eastern Townships, Quebec. Canadian Mineralogist, 8, 519–522.Search in Google Scholar
Crawford, A.J., and Berry, R.F. (1992) Tectonic implications of Late Proterozoic-Early Palaeozoic igneous rock associations in western Tasmania. Tectonophysics, 214, 37–56.10.1016/0040-1951(92)90189-DSearch in Google Scholar
Davidson, G.J., Paterson, H., Meffre, S., and Berry, R.F. (2007) Characteristics and origin of the oak dam East Breccia-hosted, iron oxide Cu-U-(Au) deposit: Olympic Dam region, Gawler Craton, South Australia. Economic Geology, 102, 1471–1498.10.2113/gsecongeo.102.8.1471Search in Google Scholar
Dill, H.G. (2010) The “chessboard” classification scheme of mineral deposits: Mineral-ogy and geology from aluminum to zirconium. Earth-Science Reviews, 100, 1–420.10.1016/j.earscirev.2009.10.011Search in Google Scholar
Early, J.W. (1958) On chlorine in serpentinized dunite. American Mineralogist, 43, 148–155.Search in Google Scholar
Eckstrand, O.R. (1975) The Dumont serpentinite: A model for control of nickeliferous opaque mineral assemblages by alteration reactions in ultramafic rocks. Economic Geology, 70, 183–201.10.2113/gsecongeo.70.1.183Search in Google Scholar
Elias, M. (2002) Nickel laterite deposits—a geological overview, resources and exploitation. Centre for Ore Deposit Research Special Publication 4, 205–220. University of Tasmania, Hobart.Search in Google Scholar
Frost, B.R. (1975) Contact metamorphism of serpentinite, chloritic blackwall and rodingite at paddy-go-easy pass, central cascades, Washington. Journal of Petrology, 16, 272–313.10.1093/petrology/16.1.272Search in Google Scholar
González-Álvarez, I., Pirajno, F., and Kerrich, R. (2013) Hydrothermal nickel deposits: Secular variation and diversity. Ore Geology Reviews, 52, 1–3.10.1016/j.oregeorev.2012.11.006Search in Google Scholar
Guillon, J.H., and Lawrence, L.J. (1973) The opaque minerals of the ultramafic rocks of New Caledonia. Mineralium Deposita, 8, 115–126.10.1007/BF00206122Search in Google Scholar
Gulson, B.L., and Porritt, P.M. (1987) Base metal exploration of the Mount Read volcanics, western Tasmania: II. Lead isotope signatures and genetic implications. Economic Geology, 82, 291–307.10.2113/gsecongeo.82.2.291Search in Google Scholar
Gulson, B.L., Large, R.R., and Porritt, P.M. (1987) Base metal exploration of the Mount Read volcanics, western Tasmania: III. Application of lead isotopes at Elliott Bay. Economic Geology, 82, 308–327.10.2113/gsecongeo.82.2.308Search in Google Scholar
Hoatson, D.M., Jaireth, S., and Jaques, A.L. (2006) Nickel sulfide deposits in Australia: Characteristics, resources, and potential. Ore Geology Reviews, 29, 177–241.10.1016/j.oregeorev.2006.05.002Search in Google Scholar
Jarosewich, E.J., Nelen, J.A., and Norberg, J.A. (1980) Reference samples for electron microprobe analysis. Geostandards Newsletter, 4, 43–47.10.1111/j.1751-908X.1980.tb00273.xSearch in Google Scholar
Kamenetsky, V.S., Crawford, A.J., Eggins, S.M., and Mühe, R. (1997) Phenocrysts and melt inclusion chemistry of near-axis seamounts, Valu Fa Ridge, Lau Basin: Insight into mantle wedge melting and the addition of subduction components. Earth and Planetary Science Letters, 151, 205–223.10.1016/S0012-821X(97)81849-3Search in Google Scholar
Kamenetsky, V.S., Binns, R.A., Gemmell, J.B., Crawford, A.J., Mernagh, T.P., Maas, R., and Steele, D. (2001a) Parental basaltic melts and fluids in eastern Manus backarc basin: Implications for hydrothermal mineralisation. Earth and Planetary Science Letters, 184, 685–702.10.1016/S0012-821X(00)00352-6Search in Google Scholar
Kamenetsky, V.S., Crawford, A.J., and Meffre, S. (2001b) Factors controlling chemistry of magmatic spinel: an empirical study of associated olivine, Cr-spinel and melt inclusions from primitive rocks. Journal of Petrology, 42, 655–671.10.1093/petrology/42.4.655Search in Google Scholar
Kamenetsky, V.S., Sobolev, A.V., Eggins, S.M., Crawford, A.J., and Arculus, R.J. (2002) Olivine-enriched melt inclusions in chromites from a low-Ca boninite, Cape Vogel, Papua New Guinea: Evidence for ultramafic primary magma, refractory mantle source and enriched components. Chemical Geology, 183, 287–303.10.1016/S0009-2541(01)00380-1Search in Google Scholar
Keays, R.R., and Jowitt, S.M. (2013) The Avebury Ni deposit, Tasmania: A case study of an unconventional nickel deposit. Ore Geology Reviews, 52, 4–17.10.1016/j.oregeorev.2012.07.001Search in Google Scholar
Keays, R.R., Jowitt, S.M., and Callaghan, T. (2009) The Avebury Ni deposit, Tasmania: a case study of an unconventional nickel deposit. In P. J. Williams, Ed., Smart Science for Exploration and Mining, Proceedings of the Tenth Biennial SGA Meeting, p. 173–175, Townsville, Australia.Search in Google Scholar
Lygin, A.V., Foster, J.G., and Hutchinson, D. (2010a) A new style of Ni-mineralization resulting from the interaction of ultramafic rocks with hydrothermal fluids derived from granites: Avebury Ni-deposit, Western Tasmania. 11th International Platinum Symposium, Miscellaneous Release-Data, vol. 269. Ontario Geological Survey, Sudbury, Ontario.Search in Google Scholar
Lygin, A.V., Foster, J.G., Hutchinson, D., and Callaghan, T. (2010b) The mineralogy and geochemistry of the Avebury Ni-deposit, Western Tasmania. 13th Quadrennial IAGOD Symposium, p. 96–97, Adelaide, Australia.Search in Google Scholar
Maas, R., Kamenetsky, M.B., Sobolev, A.V., Kamenetsky, V.S., and Sobolev, N.V. (2005) Sr, Nd, and Pb isotope evidence for a mantle origin of alkali chlorides and carbonates in the Udachnaya kimberlite, Siberia. Geology, 33, 549–552.10.1130/G21257.1Search in Google Scholar
McClenaghan, M.P. (2006) The geochemistry of Tasmanian Devonian–Carboniferous granites and implications for the composition of their source rocks, Record 2006/06, 31. Tasmanian Geological Survey, Australia.Search in Google Scholar
Miura, Y., Rucklidge, J., and Nord, G.L. (1981) The occurrence of chlorine in serpentine minerals. Contributions to Mineralogy and Petrology, 76, 17–23.10.1007/BF00373679Search in Google Scholar
Mortensen, J.K., Gemmell, J.B., McNeill, A.W., and Friedman, R.M. (2015) High-precision U-Pb zircon chronostratigraphy of the Mount Read Volcanic belt in Western Tasmania, Australia: Implications for VHMS deposit formation. Economic Geology, 110, 445–468.10.2113/econgeo.110.2.445Search in Google Scholar
Münker, C. (2000) Pb-Nd isotopes indicate the origin of Island Arc Terranes in the early Paleozoic Pacific. Journal of Geology, 108, 233–242.10.1086/314398Search in Google Scholar
Naldrett, A.J. (1999) World-class Ni-Cu-PGE deposits: Key factors in their genesis. Mineralium Deposita, 34, 227–240.10.1007/s001260050200Search in Google Scholar
Neumann, E.R., Abu El-Rus, M.A., Tiepolo, M., Ottolini, L., Vannucci, R., and Whitehouse, M. (2015) Serpentinization and deserpentinization reactions in the upper mantle beneath Fuerteventura revealed by peridotite xenoliths with fibrous orthopyroxene and mottled olivine. Journal of Petrology, 56, 3–31.10.1093/petrology/egu069Search in Google Scholar
Nickel, E.H. (1959) The occurrence of native nickel-iron in the serpentine rock of the Eastern Townships of Quebec Province. Canadian Mineralogist, 6, 307–319.10.4095/306673Search in Google Scholar
O’Hanley, D.S. (1996) Serpentinites: Records of tectonic and petrological history. Oxford University Press, U.K.Search in Google Scholar
Orberger, B., Metrich, N., Mosbah, M., Mevel, C., and Fouquet, Y. (1999) Nuclear microprobe analysis of serpentine from the Mid-Atlantic Ridge. Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms, 158, 575–581.10.1016/S0168-583X(99)00342-0Search in Google Scholar
Peck, D.C. (1990) The platinum-group element geochemistry and petrogenesis of the Heazlewood River mafic-ultramafic complex, Tasmania, 566 p. Ph.D. thesis, University of Melbourne.Search in Google Scholar
Petrus, J.A., and Kamber, B.S. (2012) VizualAge: A novel approach to laser ablation ICP-MS U-Pb geochronology data reduction. Geostandards and Geoanalytical Research, 36, 247–270.10.1111/j.1751-908X.2012.00158.xSearch in Google Scholar
Pinsent, R.H., and Hirst, D.M. (1977) The metamorphism of the Blue River ultramafic body, Cassiar, British Columbia, Canada. Journal of Petrology, 18, 567–594.10.1093/petrology/18.4.567Search in Google Scholar
Ramdohr, P. (1967) A widespread mineral association, connected with serpentinization. Neues Jahrbuch Mineralogie Abhandlungen, 107, 241–265.Search in Google Scholar
Rubenach, M.J. (1973) The Tasmanian ultramafic-gabbro and ophiolite complexes, 213 p. Ph.D. thesis, University of Tasmania, Australia.Search in Google Scholar
Rucklidge, J.C., and Patterson, G.C. (1977) The role of chlorine in serpentinization. Contributions to Mineralogy and Petrology, 65, 39–44.10.1007/BF00373568Search in Google Scholar
Scambelluri, M., Piccardo, G.B., Philippot, P., Robbiano, A., and Negretti, L. (1997) High salinity fluid inclusions formed from recycled seawater in deeply subducted alpine serpentinite. Earth and Planetary Science Letters, 148, 485–499.10.1016/S0012-821X(97)00043-5Search in Google Scholar
Sciortino, M., Mungall, J.E., and Muinonen, J. (2015) Generation of High-Ni sulfide and alloy phases during serpentinization of dunite in the Dumont sill, Quebec. Economic Geology, 110, 733–761.10.2113/econgeo.110.3.733Search in Google Scholar
Sigurdsson, I.A., Kamenetsky, V.S., Crawford, A.J., Eggins, S.M., and Zlobin, S.K. (1993) Primitive island arc and oceanic lavas from the Hunter ridge-Hunter fracture zone. Evidence from glass, olivine and spinel compositions. Mineralogy and Petrology, 47, 149–169.10.1007/BF01161564Search in Google Scholar
Solomon, M., Gemmell, J.B., and Zaw, K. (2004) Nature and origin of the fluids responsible for forming the Hellyer Zn-Pb-Cu, volcanic-hosted massive sulphide deposit, Tasmania, using fluid inclusions, and stable and radiogenic isotopes. Ore Geology Reviews, 25, 89–124.10.1016/j.oregeorev.2003.11.001Search in Google Scholar
Stacey, J.S., and Kramers, J.D. (1975) Approximation of terrestrial lead isotope evolution by a two-stage model. Earth and Planetary Science Letters, 26, 207–221.10.1016/0012-821X(75)90088-6Search in Google Scholar
Tian, Y., Etschmann, B., Liu, W., Borg, S., Mei, Y., Testemale, D., O’Neill, B., Rae, N., Sherman, D.M., Ngothai, Y., Johannessen, B., Glover, C., and Brugger, J. (2013) Speciation of nickel (II) chloride complexes in hydrothermal fluids: In situ XAS study. Chemical Geology, 334, 345–363.10.1016/j.chemgeo.2012.10.010Search in Google Scholar
Vance, J.A., and Dungan, M.A. (1977) Formation of peridotites by deserpentinization in Darrington and Sultan areas, Cascade Mountains, Washington. Geological Society of America Bulletin, 88, 1497–1508.10.1130/0016-7606(1977)88<1497:FOPBDI>2.0.CO;2Search in Google Scholar
© 2016 by Walter de Gruyter Berlin/Boston
