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The role of fluids in the metamorphism of komatiites, Agnew nickel deposit, western Australia

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Abstract

The Agnew nickel sulfide deposit is spatially associated with a lenticular body of ultramafic rocks which shows a concentric zonation in metamorphic mineralogy. Olivine + tremolite + chlorite + cummingtonite ±enstatite assemblages occur at the margin of the ultramafic lens, giving way to olivine + anthophyllite, olivine + talc and olivine + antigorite assemblages successively inwards. These rocks are interpreted as having crystallized from komatiitic lavas, and exhibit a spectrum of compositions from those of original flow tops to pure olivine adcumulates. The relative modal abundances of metamorphic olivine, tremolite and chlorite reflect original proportions of cumulus olivine and komatiite liquid in the protolith. Peak metamorphic conditions are estimated at 550° C, based on garnet-biotite thermometry, at a maximum pressure of 3 kb. This temperature falls within the narrow range over which metamorphic olivine may co-exist with enstatite, anthophyllite, talc or antigorite depending upon the fugacity of water in the metamorphic fluid. The observed mineralogical zonation is therefore attributed to infiltration by CO2-rich fluids, generated by decarbonation of talc-carbonate rocks formed during pre-metamorphic marginal alteration of the ultramafic lens. Metamorphic fluids were essentially binary mixtures of water and CO2, with minor H2S having a maximum partial pressure less than 1 percent of total pressure. Enstatite-bearing assemblages formed in the presence of CO2-rich fluids at fluid: rock volume ratios close to one, while anthophyllite, talc and antigorite bearing assemblages formed in the presence of progressively more water-rich fluids at progressively lower fluid-rock ratios.

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References

  • Archibald NJ, Bettenay LF, Binns RA, Groves DI, Gunthorpe RJ (1978) The evolution of Archean greenstone terrains, Eastern Goldfields Province, Western Australia. Precamb Res 6:103–131

    Google Scholar 

  • Billington LG (1984) Geological review of the Agnew nickel deposit, Western Australia. In: Buchanan DL, Jones MJ (eds) Sulphide deposits in mafic and ultramafic rocks. Inst Mining Metall, London, pp 43–54

    Google Scholar 

  • Binns RA, Champness PE (1985) Analytical electron microscope study of red-brown olivines in ultramafic rocks from the Yilgarn Block, W.A. CSIRO Division of Mineralogy and Geochemistry Research Review 1985, CSIRO, Canberra, pp 32–33

    Google Scholar 

  • Binns RA, Groves DI (1976) Iron-nickel partition in metamorphosed olivine-sulfide assemblages from Perseverance, Western Australia. Am Mineral 61:782–787

    Google Scholar 

  • Binns RA, Gunthorpe RJ, Groves DI (1976) Metamorphic patterns and development of greenstone belts in the Eastern Yilgarn Block, Western Australia. In: Windley BF (ed) The Early History of the Earth. Wiley, London, pp 303–313

    Google Scholar 

  • Burt DRL, Sheppey NR (1975) Mount Keith nickel sulfide deposit. In: Knight CL (ed) Economic Geology of Australia and Papua New Guinea, vol I. Metals: Melbourne, Australian. Inst Mining Metall Mon 5:159–168

  • Chernosky JV, Day HW, Caruso LJ (1985) Equilibria in the system MgO-SiO2-H2O: experimental determination of the stability of Mg-anthophyllite. Am Mineral 70:223–236

    Google Scholar 

  • Day HW, Chernosky JV, Kumin HJ (1985) Equilibria in the system MgO-SiO2-H2O: a thermodynamic analysis. Am Mineral 70:237–248

    Google Scholar 

  • Eckstrand OR (1975) The Dumont serpentinite — A model for control of nickeliferous opaque mineral assemblages by alteration reactions in ultramafic rock. Econ Geol 70:183–201

    Google Scholar 

  • Evans BW, Tromsdorff V (1974) Stability of enstatite + talc, and CO2 metasomatism of metaperidotite, Val d'Efra, Lepontine Alps. Am J Sci 274:274–296

    Google Scholar 

  • Evans BW, Tromsdorff V (1974a) On elongate olivine of metamorphic origin. Geology 1:131–132

    Google Scholar 

  • Ferry JM, Spear FS (1978) Experimental calibration of the partitioning of Fe and Mg between biotite and garnet. Contrib Mineral Petrol 66:113–117

    Google Scholar 

  • Frost BR (1974) Contact metamorphism of serpentinite, chloritic blackwall and rodingite at Paddy-Go-Easy Pass, Central Cascades, Washington. J Petrol 16:272–313

    Google Scholar 

  • Frost BR (1979) Mineral equilibria involving mixed volatiles in a C-O-H fluid phase: the stabilities of graphite and siderite. Am J Sci 279:1033–1059

    Google Scholar 

  • Gole MJ, Hill RET, Barnes SJ (1986) Komatiite flows and lava lakes — environments of formation of spinifex and adcumulate textures. Int Volcanol Cong, New Zealand, p 352

    Google Scholar 

  • Hill RET, Gole MJ, Thompson JFH (1985) Characteristics of centres of Archean komatiitic volcanism, exemplified by lithologies in the Agnew area, Yilgarn Block, Western Australia. Can Mineral 23:327

    Google Scholar 

  • Holdaway MJ (1971) Stability of andalusite and the aluminium silicate phase diagram. Am J Sci 271:97–131

    Google Scholar 

  • Holdaway MJ, Lee SM (1977) Fe-Mg cordierite stability in high grade pelitic rocks based on experimental, theoretical and natural observations. Contrib Mineral Petrol 63:175–193

    Google Scholar 

  • Jenkins DM (1983) Stability and composition relations of calcic amphiboles in ultramafic rocks. Contrib Mineral Petrol 83:375–384

    Google Scholar 

  • Johannes W (1969) An experimental investigation of the system MgO-SiO2-H2O-CO2. Am J Sci 267:1083–1104

    Google Scholar 

  • Kerrick DM, Jacobs GK (1981) A modified Redlich-Kwong equation for H2O, CO2 and H2O-CO2 mixtures at elevated pressures and temperatures. Am J Sci 281:735–767

    Google Scholar 

  • Martin JE, Allchurch PD (1975) Perseverance nickel deposit, Agnew. In: Knight CL (ed) Economic geology of Australia and Papua New Guinea. I. Metals. Australian Inst Mining Metall Monogr 5:149–155

  • Morse SA (1979) Reaction constants for En-Fo-Si equilibrium: an adjustment and applications. Am J Sci 279:1060–1069

    Google Scholar 

  • Mueller RF (1973) System CaO-MgO-FeO-SiO2-C-H2-O2: some correlations from nature and experiment. Am J Sci 273:152–170

    Google Scholar 

  • Myers J, Eugster HP (1983) The system Fe-Si-O: oxygen buffer calibrations to 1,500 K. Contrib Mineral Petrol 82:75–90

    Google Scholar 

  • Naldrett AJ (1973) Nickel sulphide deposits — Their classification and genesis, with special emphasis on deposits of volcanic association. CIM Bull 66:45–63

    Google Scholar 

  • Naldrett AJ, Turner AR (1977) The geology & petrogenesis of a greenstone belt & related nickel sulphide mineralisation at Yakabindie, Western Australia. Precamb Res 3:43–103

    Google Scholar 

  • Newton RC, Haselton HT (1981) Thermodynamics of the garnet-plagioclase-Al2SiO5-quartz geobarometer. In: Newton RC, Navrotsky A, Wood BJ (eds) Thermodynamics of minerals and melts. Springer, Berlin Heidelberg New York, pp 131–147

    Google Scholar 

  • Porter DJ, McKay KG (1981) The nickel sulfide mineralization and metamorphic setting of the Forrestania Area, Western Australia. Econ Geol 76:1524–1549

    Google Scholar 

  • Rice JM, Ferry JM (1982) Buffering, infiltration and control of intensive variables during metamorphism. In: Ferry JM (ed) Characterization of metamorphism through mineral equilibria. Rev Mineral 10:263–324

    Google Scholar 

  • Rice JM, Evans BW, Tromsdorff V (1974) Widespread occurrence of magnesiocummingtonite in ultramafic schists, Cina di Gagnone, Ticino, Switzerland. Contrib Mineral Petrol 43:245–251

    Google Scholar 

  • Robinson P, Spear FS, Schumacher JC, Laird J, Klein C, Evans BW, Doolan BL (1982) Phase relations of metamorphic amphiboles: natural occurrence and theory. In: Veblen DR, Ribbe PH (eds) Amphiboles, petrology and experimental phase relations. Rev Mineral 9B: 1–211

  • Sack RO (1980) Some constraints on the thermodynamic mixing properties of Fe-Mg orthopyroxenes and olivines. Contrib Mineral Petrol 71:257–269

    Google Scholar 

  • Scotford DM, Williams JR (1983) Petrology and geochemistry of metamorphosed ultramafic bodies in a portion of the Blue Ridge of North Carolina and Virginia. Am Mineral 68:78–94

    Google Scholar 

  • Shmonov VM, Shmulovich KI (1974) Molar volumes and the equation of state for CO2 at 100–1000° C and 2000–10000 bar. Akad Nauk SSSR Dokl 217:205–209

    Google Scholar 

  • Skippen G (1974) An experimental model for low pressure metamorphism of siliceous dolomitic marble. Am J Sci 274:487–509

    Google Scholar 

  • Skippen G, McKinstry BW (1985) Synthetic and natural tremolite in equilibrium with forsterite, enstatite, diopside and fluid. Contrib Mineral Petrol 89:256–262

    Google Scholar 

  • Slaughter J, Kerrick DM, Wall VJ (1974) Experimental and thermodynamic study of equilibria in the system CaO-MgO- SiO2-CO2-H2O. Am J Sci 275:143–162

    Google Scholar 

  • Toulmin III P, Barton PB Jr (1964) A thermodynamic study of pyrite and pyrrhotite. Geochim Cosmochim Acta 28:641–671

    Google Scholar 

  • Tromsdorff V, Evans BW (1972) Progressive metamorphism of antigorite schist in the Bergell Tonalite aureole, Italy. Am J Sci 272:423–437

    Google Scholar 

  • Whitney JA (1984a) Fugacities of sulfurous gases in pyrrhotite-bearing silicic magmas. Am Mineral 78:69–78

    Google Scholar 

  • Whitney JA (1984b) Volatiles in magmatic systems. In: Fluid-mineral equilibria in hydrothermal systems. Rev Econ Geol 1:155–176

    Google Scholar 

  • Zeuch DH, Green II HW (1984) Experimental deformation of a synthetic dunite at high temperature and pressure. I. Mechanical behaviour, optical microstructure and deformation mechanism. Tectonophysics 110:233–262

    Google Scholar 

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Authors and Affiliations

  1. Division of Minerals and Geochemistry, C.S.I.R.O., Private Bag, 6014, Wembley, Western Australia

    Martin J. Gole, Stephen J. Barnes & Robin E. T. Hill

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  1. Martin J. Gole
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  2. Stephen J. Barnes
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  3. Robin E. T. Hill
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Gole, M.J., Barnes, S.J. & Hill, R.E.T. The role of fluids in the metamorphism of komatiites, Agnew nickel deposit, western Australia. Contr. Mineral. and Petrol. 96, 151–162 (1987). https://doi.org/10.1007/BF00375229

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  • DOI: https://doi.org/10.1007/BF00375229

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