Hostname: page-component-78c5997874-j824f Total loading time: 0 Render date: 2024-11-06T06:17:23.776Z Has data issue: false hasContentIssue false
  • English
  • Français

Apparent pyrrhotite-chalcopyrite solid solutions in charnockites: the Shevaroy Hills Massif, Tamil Nadu, S India and the Bamble Sector, SE Norway

Published online by Cambridge University Press:  05 July 2018

D. E. Harlov
D. E. Harlov*
Affiliation:
GeoForschungsZentrum Potsdam, Telegrafenberg, D-14473 Potsdam, Germany
*
*E-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

Examples of apparent exsolution lamellae and lenticular blebs of chalcopyrite in pyrrhotite are described in orthopyroxene-bearing granulite facies rocks from two, oxidized (log10fO2 = −14 to −11), widely separated, well characterized high grade terranes: the Bamble Sector, SE Norway (795°C, 7.5 kbar) and the Shevaroy Hills Massif, Tamil Nadu, S India (750°C, 7.5 kbar). These exsolution features only occur in isolated pyrrhotite grains and not in integral pyrrhotite-pyrite-chalcopyrite-magnetite grain clusters which essentially represent an oxidation equilibrium. Reintegration of these chalcopyrite exsolution features back into the pyrrhotite host indicate Cu contents ranging from 1 to 5 wt.% in good agreement with experimental observations which indicate that pyrrhotite can take up to 7 wt.% Cu at temperatures above 800°C at pressures of ∼1 bar. This suggests that under high grade conditions these chalcopyrite exsolution features were in solid solution with pyrrhotite. Whether Cu stabilizes pyrrhotite at higher oxygen fugacities or these chalcopyrite-pyrrhotite grains represent a metastable phase is uncertain. One possibility is that the isolated pyrrhotite grains with chalcopyrite lamellae could represent grains that were preferentially not exposed to infiltrating fluids, which oxidized the pyrrhotites in other areas of the sample. A second possibility is that either these grains had enough Cu to stabilize them during pervasive infiltration of oxidizing fluids or that they represent a metastable phase with respect to the overall oxygen fugacity of the sample. The two conclusions that can be drawn from these observations are, firstly, that it is possible for pyrrhotite and chalcopyrite to form a limited solid solution at granulite facies temperatures and pressures under relatively high oxidizing conditions, i.e. 1.5 log units above fayalite-magnetite-quartz, at 800°C and 8 kbar. Secondly, this limited solid solution should have some bearing on the stability of pyrrhotite with respect to co-existing magnetite and pyrite as a function of the oxidation state of the rock, be it inherited or fluid induced.

Keywords

pyrrhotite-chalcopyritesolid solutioncharnockiteIndiaNorway
Type
Research Article
Information
Mineralogical Magazine , Volume 64 , Issue 5 , October 2000 , pp. 853 - 865
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2000

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Åhall, K.I., Cornell, D.H. and Armstrong, R. (1998) Ion probe zircon dating of metasedimentary units across Skagerrak, new constraints for early Mesoproterozoic growth of the Baltic Shield. Precamb. Res., 87, 117–35.CrossRefGoogle Scholar
Amcoff, O. (1981) Heating experiments of chalcopyrite-pyrrhotite ores: studies on the stability of the intermediate solid solution. Neues Jahrb. Mineral. Mh., 553-68.Google Scholar
Bohlen, S.R. and Essene, E.J. (1977) Feldspar and oxide thermometry of granulites in the Adirondack Highlands. Contrib. Mineral. Petrol, 62, 153–69.CrossRefGoogle Scholar
Buddington, A.F. and Lindsley, D.H. (1964) Iron-titanium oxide minerals and synthetic equivalents. J. Petrol., 5, 310–57.CrossRefGoogle Scholar
Cabri, L.J. (1973) New data on phase relations in the Cu-Fe-S system. Econ. Geol., 68, 443–54.CrossRefGoogle Scholar
Cameron, E.M., Cogulu, E.H. and Stirling, J. (1993) Mobilization of gold in the deep crust: evidence from mafic intrusions in the Bamble belt, Norway. Lithos, 30, 151–66.CrossRefGoogle Scholar
Craig, J.R. and Scott, S.D. (1974) Sulphide phase equilibria. Pp. CS1–109 in: Sulphide Mineralogy (Ribbe, P.H., editor). Reviews in Mineralogy, 1. Mineralogical Society of America, Washington, D. C. Google Scholar
Edwards, A.B. (1954) Textures of the Ore Minerals and their Significance. Brown, Prior, Anderson Pty Ltd., London.Google Scholar
Field, D., Drury, S.A. and Cooper, D.C. (1980) Rare-earth and LIL fractionation in high-grade charnockitic gneisses, South Norway. Lithos, 13, 281–9.CrossRefGoogle Scholar
Field, D, Smalley, P.C., Lamb, R.C. and Raheim, A. (1985) Geochemical evolution of the 1.6–1.5 Ga old amphibolite-granulite facies terrain, Bamble Sector, Norway: dispelling the myth of Grenvillian high-grade reworking. Pp. 567–78 in: The Proterozoic Crust in the North Atlantic Provinces (Tobi, A.C. and Touret, J.L.R., editors). Reidel, Berlin.CrossRefGoogle Scholar
Franz, L. and Harlov, D.E. (1998) High-grade K-feldspar veining in granulites from the Ivrea-Verbano Zone, northern Italy: fluid flow in the lower crust and implications for granulite facies genesis. J. Geol., 106, 455–72.CrossRefGoogle Scholar
Frost, B.R. (1991) Magnetic petrology: factors that control the occurrence of magnetite in crustal rocks. Pp. 489–509 in: Oxide Minerals: Petrologic and Magnetic Significance (Lindsley, D.H., editor). Reviews in Mineralogy, 25. Mineralogical Society of America, Washington, D.C. CrossRefGoogle Scholar
Frost, B.R., Lindsley, D.H. and Andersen, D.J. (1988) Fe-Ti oxide-silicate equilibria: assemblages with fayalitic olivine. Amer. Mineral., 73, 727–40.Google Scholar
Ghiorso, M.S. (1990) Thermodynamic properties of hematite-ilmenite-geikielite solid solutions. Contrib. Mineral. Petrol., 104, 645–67.CrossRefGoogle Scholar
Ghiorso, M.S. and Sack, R.O. (1991) Fe-Ti oxide geothermometry: thermodynamic formulation and the estimation of intensive variables in silicic magmas. Contrib. Mineral. Petrol., 108, 485–510.CrossRefGoogle Scholar
Hagelia, P. (1995) Rb-Sr-systematics of the Proterozoic Bamble and Telemark sectors, south Norway: myths and reality. Geonytt, 22, 33–4.Google Scholar
Hansen, E.C., Newton, R.C., Janardhan, A.S. and Lindenberg, S. (1995) Differentiation of Late Archean crust in the Eastern Dharwar Craton, South India. J. Geol., 103, 629–51.CrossRefGoogle Scholar
Harlov, D.E. (1992) Comparative oxygen barometry in granulites, Bamble Sector, S.E. Norway. J. Geol., 100, 447–64.CrossRefGoogle Scholar
Harlov, D.E. (2000 a) Pressure-temperature estimation in orthopyroxene-garnet bearing granulite facies rocks, Bamble Sector, Norway. Mineral. Petrol., 69, 11–33.CrossRefGoogle Scholar
Harlov, D.E. (2000 b) Titaniferous magnetite-ilmenite thermometry and titaniferous magnetite-ilmenite-orthopyroxene-quartz oxygen barometry in granulite fades gneisses, Bamble sector, SE Norway: constraints on the role of high grade CO2-rich fluids during granulite genesis. Contrib. Mineral. Petrol., 139, 180–97.CrossRefGoogle Scholar
Harlov, D.E. and Sack, R.O. (1995) Thermochemistry of Ag2S-Cu2S sulphide solutions: constraints derived from coexisting Sb2S3- and As2S3-bearing sulpho-salts. Geochim. Cosmochim. Acta, 59, 4351–65.CrossRefGoogle Scholar
Harlov, D.E., Newton, R.C., Hansen, E.C. and Janardhan, A.S. (1997) Oxide and sulphide minerals in highly oxidised, Rb-depleted, Archean granulites of the Shevaroy Hills Massif, South India: oxidation states and the role of metamorphic fluids. J. Metam. Geol., 15, 701–17.CrossRefGoogle Scholar
Harlov, D.E., Hansen, E.C. and Bigler, C. (1998) Petrologic evidence for K-feldspar metasomatism in granulite facies rocks. Chem. Geol., 151, 373–86.CrossRefGoogle Scholar
Klein, C. and Hurlbut, C.S. (1993) Manual of Mineralogy - 21st Edition. John Wiley & Sons, Inc., New York.Google Scholar
Knudsen, T.L., Andersen, T., Whitehouse, M.J. and Veston, J. (1997) Detrital zircon ages from Southern Norway – implications for the Proterozoic evolution of the Southwestern part of the Baltic Shield. Contrib. Mineral. Petrol., 130, 47–58.CrossRefGoogle Scholar
Kojima, S. and Sugaki, A. (1984) Phase relations in the central portion of the Cu-Fe-Zn-S system between 800°C and 500°C. Mineral. J., 12, 15–28.CrossRefGoogle Scholar
Kullerud, L. and Dahlgren, S. (1993) Sm-Nd geochronology of Sveconorwegian granulite facies mineral assemblages in the Bamble shear belt, South Norway. Precamb. Res., 64, 389–402.CrossRefGoogle Scholar
Kullerud, G., Yund, R.A. and Moh, G.H. (1969) Phase relations in the Cu-Fe-S, Cu-Ni-S, and Fe-Ni-S systems. Pp. 323–43 in: Magmatic Ore Deposits, A Symposium. Economic Geology Monographs, 4.Google Scholar
Lamb, R.C., Smalley, P.C. and Field, D. (1986) P-T conditions for the Arendal granulites, Southern S.E. Norway: implications for the roles of P, T, and CO2 in deep crustal LILE-depletion. J. Metam. Geol., 4, 143–60.CrossRefGoogle Scholar
Moine, B., de la Roche, H. and Touret, J. (1972) Structures géochimique et zonéographie métamorphique dans le Précambrien catazonal du sud de la Norvège. Science de la Terre, 17, 131–64.Google Scholar
Morikiyo, T., Inaba, M. and Sugai, H. (1993) Coexisting pyrrhotite and chalcopyrite in the Ryoke metamorphic rocks, northern Kiso-Ina district. J. Mineral., Petrol. Econ. Geol., 88, 307–12.CrossRefGoogle Scholar
Mukaiyama, H. and Izawa, E. (1970) Phase relations in the Cu-Fe-S system: the copper-deficient part. Pp. 339–55 in: Volcanism and Ore Genesis. University of Tokyo Press, Tokyo.Google Scholar
Nijland, T.G. and Maijer, C. (1993) The regional amphibolite to granulite facies transition at Arendal, Norway: evidence for a thermal dome. Neues Jahrb. Min. Ab., 165, 191–221.Google Scholar
Smalley, P.C., Field, D., Lamb, R.C. and Clough, P.W.L. (1983) Rare earth, Th-Hf-Ta and large-ion lithophile element variations in metabasites from the Proterozoic amphibolite-granulite transition zone at Arendal, South Norway. Earth Planet. Sci. Lett., 63, 446–58.CrossRefGoogle Scholar
Starmer, I.C. (1985) The evolution of the South Norwegian Proterozoic as revealed by the major and mega-tectonics of the Kongsberg and Bamble Sectors. Pp. 259–90 in: The Deep Proterozoic Crust in the North Atlantic Provinces (Tobi, A.C. and Touret, J. L.R., editors). Reidel, Berlin.CrossRefGoogle Scholar
Starmer, I.C. (1986) Geological Map of the Bamble Sector, South Norway 1:100,000): 3 Sheets. NATO Advanced Study Institute 1984 Excursion Guide. In: The Geology of Southernmost Norway: An Excursion Guide (Maijer, C. and Padget, P., editors). Norges Geologiske Undersokelse, Spec. Publ. 1.Google Scholar
Starmer, I.C. (1990) Mid-Proterozoic evolution of the Kongsberg-Bamble belt and adjacent areas, Southern Norway. Pp. 279–305 in: Mid-Proterozoic Laurentia-Baltica (Gower, C.F., Rivers, C.F. and Ryan, B., editors). Geological Association of Canada, Spec. Paper, 38.Google Scholar
Starmer, I.C. (1996) Oblique terrain assembly in the late Paleo-Proterozoic during the Labradorian-Gothian orogeny in Southern Scandinavia. J. Geol., 104, 341–50.CrossRefGoogle Scholar
Todd, C.S. and Evans, B.W. (1994) Properties of CO2-induced dehydration of amphibolite. J. Petrol., 35, 1213–40.CrossRefGoogle Scholar
Touret, J.L.R. (1985) Fluid regime in Southern Norway: the record of fluid inclusions. Pp. 517–49 in: The Deep Proterozoic Crust in the North Atlantic Provinces (Tobi, A.C. and Touret, J. L.R., editors). Reidel, Berlin.CrossRefGoogle Scholar
Wiggins, L.B. and Craig, J.R. (1980) Reconnaissance of the Cu-Fe-Zn-S system: sphalerite phase relationships. Econ. Geol, 75, 742–51.CrossRefGoogle Scholar
Yund, R.A. and Kullerud, G. (1966) Thermal stability of assemblages in the Cu-Fe-S system. J. Petrol., 7, 454–88.CrossRefGoogle Scholar