Hostname: page-component-cd9895bd7-lnqnp Total loading time: 0 Render date: 2024-12-25T07:13:26.563Z Has data issue: false hasContentIssue false
  • English
  • Français

Nature and evolution of metamorphic fluids associated with turbidite-hosted gold deposits: Hill End goldfield, NSW, Australia

Published online by Cambridge University Press:  05 July 2018

P. K. Seccombe ,
J. Ju ,
A. S. Andrew ,
B. L. Gulson  and
K. J. Mizon
P. K. Seccombe
Affiliation:
Department of Geology, The University of Newcastle, Callaghan NSW 2308, Australia
J. Ju
Affiliation:
Department of Geology, The University of Newcastle, Callaghan NSW 2308, Australia
A. S. Andrew
Affiliation:
Division of Exploration Geoscience, CSIRO, PO Box 136, North Ryde, NSW 2113, Australia
B. L. Gulson
Affiliation:
Division of Exploration Geoscience, CSIRO, PO Box 136, North Ryde, NSW 2113, Australia
K. J. Mizon
Affiliation:
Division of Exploration Geoscience, CSIRO, PO Box 136, North Ryde, NSW 2113, Australia
Get access Rights & Permissions [Opens in a new window]

Abstract

The Hill goldfield, NSW, Australia, is an example of a syntectonic, slate-belt gold deposit formed in a multiply deformed, Late Silurian slate-metagreywacke turbidite sequence. Gold is confined to bedding-parallel veins and discordant leader veins composed of as many as four generations of quartz, accompanied by phyllosilicates, carbonates and minor sulphides. Vein formation and gold deposition was apparently synchronous with Early Carboniferous metamorphism and deformation. Homogenisation temperatures (Th) for fluid inclusions in vein quartz demonstrate five groupings in the temperature intervals 350-280°C 280-250°C 250-190°C 190-150°C and 150-110°C corresponding to a variety of primary and secondary inclusions developed during four periods of vein quartz deposition under a generally declining temperature regime. Inclusion fluids are characterised by a low salinity of around 0.1 to 3.6 wt. % NaCl equivalent. The dominant gas phase present in the inclusion fluids varies from N2 in the early stages of the paragenesis, through CH 4 during the main episode of gold deposition, to CO2- rich fluids associated with late-stage mineralisation. δ18O values for vein quartz (range 15.1-17.1‰) and vein carbonate (range 11.3-13.4‰) are typical of metamorphic mineralisation. δD composition of hydrous minerals and inclusion fluids (range −53 to −138‰) suggest an influx of meteoric water in the later mineralising fluids. This conclusion is supported by δ13C data for vein calcite (range −2.5 to −9.7%0). δ34S composition of vein pyrrhotite and pyrite ranges from 6.9 to 7.8‰ early in the paragenesis, to lighter values (around 4.2 to 5.8%0) accompanying late gold deposition from more oxidising fluids. Sulphur isotope data imply a sulphur source from underlying turbidites and an increase in fluid oxidation state during mineralisation . Lead isotope measurements on vein pyrite, arseno py rite, galena and gold are characterised by two isotope populations with 207Pb/206Pb ratios of 0.862 and 0.860, which define two discrete mineralising events during vein formation. Consistency between data from vein minerals and lead isotope signatures for potential source rocks indicate that lead was derived from the sedimentary pile.

Keywords

fluid inclusionsstable isotopeslead isotopesgoldmetamorphic fluidsAustralia
Type
Research Article
Information
Mineralogical Magazine , Volume 57 , Issue 388 , September 1993 , pp. 423 - 436
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1993

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

Bigeleisen, J., Pearlman, M. L., and Prosser, H. C. (1952) Conversion of hydrogenic materials to hydrogen for isotopic analysis. Analyt. Chem., 24, 1356–7.Google Scholar
Bottinga, Y. (1969) Calculation of fractionation factors for carbon and hydrogen isotope exchange in the system calcite-CO2—graphite-methane and water vapor. Geochim. Cosmochim. Acta, 33, 49–64.Google Scholar
Bowers, T. S. and Helgeson, H. C. (1983) Calculations of the thermodynamic and geochemical consequences of nonideal mixing in the system H2O-CO2-NaCl on phase relations in geological systems: Equation of state for H2O-CO2-NaCI fluids at high pressures and temperatures. Ibid. 47, 1247-75.Google Scholar
Brand, N. W., Bottrell, S. H., and Miller, M. F. (1989) Concentrations of reduced sulphur in inclusion fluids associated with black shale hosted quartz vein gold deposits: implications for mechanisms of transport and deposition of gold and a possible exploration tool. Appl. Geochem., 4, 483–91.Google Scholar
Clayton, R. N. and Mayeda, T. K. (1963) The use of bromine pentafluoride in the extraction of oxygen from oxides and silicates for isotopic analysis. Geochim. Cosmochim. Acta, 27, 43–52.Google Scholar
Clayton, R. N., O'Neil, J. R., and Mayeda, T. K. (1972) Oxygen isotope exchange between quartz and water. J. Geophys. Res., 77, 3057–67.Google Scholar
Collins, A. G. (1971) The morphology of slaty cleavage in the Hill End Trough. PhD thesis (unpubl.) Univ. Sydney, Australia.Google Scholar
Cox, S. F., Wall, V. J., Etheridge, M. A., and Potter, T. F. (1991) Deformational and metamorphic pro-cesses in the formation of mesothermal vein-hosted gold deposits—examples from the Lachlan Fold Belt in central Victoria, Australia. Ore Geol. Rev., 6, 391–423.Google Scholar
Cumming, G. L. and Richards, J. R. (1975) Ore lead isotope ratios in a continuously changing Earth. Earth Planet. Sci. Lett., 28, 155–71.Google Scholar
Fyfe, W. S., Price, N. J., and Thompson, A. B. (1978) Fluids in the Earth's Crust. Elsevier, Amsterdam, 383 pp.Google Scholar
Goldfarb, R. J., Leach, D. L., Pickthorn, W. J., and Paterson, C. J. (1988) Origin of lode-gold deposits of the Juneau gold belt, southeastern Alaska. Geology, 16, 440–3.Google Scholar
Hicks, M. N. (1977) The geology and quartz vein genesis of the Hawkins Hill area, Hill end, New South Wales. BSe.(hons.) thesis (unpubl.) Univ. Newcastle, Australia.Google Scholar
Ho, S. E. (1987) Fluid inclusions: their potential as an exploration tool for Archaean gold deposits. In Recent Advances in Understanding Precambrian Gold Deposits (Ho, S. E. and Groves, D. I., eds.). Geol. Dept. Univ. Western Australia, 11, 239-63.Google Scholar
Kerrich, R. (1986) Fluid infiltration into fault zones: Chemical, isotopic and mechanical effects. Pure Appl. Geophys., 124, 225–68.Google Scholar
Lu, J. and Seccombe, P. K. (1993, in press) Fluid evolution in a slate-belt gold deposit: A fluid inclusion study of the Hill End goldfield, NSW, Australia. Mineral. Deposita. Google Scholar
Lu, J. Seccombe, P. K., Walshe, J. L., Gulson, B. L., and Mizon, K. J. (1993, in press) Source of components and conditions of mineralisation in the Hill End goldfield, NSW: Evidence from S, C, O, H and Pb isotopes, fluid inclusions and the composition of chlorite. Econ. Geol. Google Scholar
McCrea, J. M. (1950) On tile isotope chemistry of carbonates and paleotemperature scale. J. Chem. Phys., 18, 849–57.Google Scholar
Mawer, C. K. (1986) The bedding-concordant gold-quartz veins of the Meguma Group, Nova Scotia. In Turbidite-hosted Gold Deposits (Keppie, J. D. et at., eds.). Geol. Assoc. Canada Special Paper, 32, 135-48.Google Scholar
Offler, R. and Prendergast, E. (1985) Significance of illite crystallinity and b0 values of K-white mica in low grade metamorphic rocks, North Hill End Synclinor-ium, New South Wales. Mineral. Mag., 49, 357–64.Google Scholar
Ohmoto, H. (1972) Systematics of sulfur and carbon isotopes in hydrothermal ore deposits. Econ. Geol., 67, 551–78.Google Scholar
Ohmoto, H. and Rye, R. O. (1979) Isotopes of sulfur and carbon. In Geochemistry of Hydrothermal Ore Deposits (Barnes, H. L., ed.). Wiley Interscience, New York, 509-67.Google Scholar
O'Neil, J. R. and Taylor, H. P. Jr., (1969) Oxygen isotope equilibrium between muscovite and water. J. Geophys. Res., 74, 6012–22.Google Scholar
Powell, C. McA. and Edgecombe, D. R. (1978) Mid-Devonian movements in the north eastern Lachlan Fold Belt. J. Geol. Soc. Austral., 25, 165–84.Google Scholar
Powell, C. McA. Edgecombe, D. R., Henry, N. M., and Jones, J. G. (1976) Timing of the regional deformation of the Hill End Trough: A reassessment. Ibid., 23, 407-21.Google Scholar
Powell, R., Will, T. M., and Phillips, G. N. (1991) Metamorphism in Archaean greenstone belts: calculated fluid compositions for gold mineralization. J. Metam. Geol., 9, 141–50.Google Scholar
Ramsay, J. G. (1980) The crack-seal mechanism of rock deformation. Nature, 284, 135–9.Google Scholar
Roedder, E. (1984) Fluid Inclusions. Reviews in Mineralogy, 12, Mineralogical Society of America, Washington, 644 pp.Google Scholar
Robinson, B. W. and Kusakabe, M. (1975) Quantita-tive preparation of sulfur dioxide for34S/3zs analyses form sulfides by combustion with cuprous oxide. Anal. Chem., 47, 1179–81.Google Scholar
Sakai, H. and Tsutsumi, M. (1978) D/H fractionation factors between serpentine and water at 100°C to 500°C and 200 bar water pressure and the D/H ratios of natural serpentines. Earth Planet. Sci. Lett., 40, 231–42.Google Scholar
Seccombe, P. K. and Hicks, M. N. (1989) The Hill End goldfield, NSW, Australia—Early metamorphic deposition of auriferous quartz veins. Mineral. Petrol., 40, 257–73.Google Scholar
Seward, T. M. (1984) The transport and deposition of gold in hydrothermal systems. In Gold ‘82: The Geology, Geochemistry and Genesis of Gold Deposits (Foster, R. P., ed.). A. A. Balkema, Rotterdam, 165-81.Google Scholar
Shepherd, T. J., Bottrell, S. H. and Miller, M. F. (1991) Fluid inclusion volatiles as an exploration guide to black shale hosted gold deposits, Dolgellau gold belt, North Wales, UK. J. Geochem. Explor., 42, 5–24.Google Scholar
Sterner, S. M. and Bodnar, R. J. (1989) Synthetic fluid inclusions-VlI. Re-equilibration of fluid inclusions in quartz during laboratory-simulated metamorphic burial and uplift. J. Met. Geol., 7, 243–450.Google Scholar
Stevens, B. P. J. (1974) Hill End synclinorial zone. In The Mineral Deposits of New South Wales (Markham, N. L. and Basden, H., eds.). Geol. Surv. New South Wales, Dept. Mines, Sydney, 276-93.Google Scholar
Suzuoki, T. and Epstein, S. (1976) Hydrogen isotope fractionation between OH-bearing minerals and water. Geochim. Cosmochim. Acta, 40, 1229–40.Google Scholar
Taylor, H. P. Jr., (1979) Oxygen and hydrogen isotope relationships in hydrothermal ore deposits. In Geochemistry of Hydrothermal Ore Deposits (Barnes, H. L., ed.). Wiley Interscience, New York, 236-77.Google Scholar
Walshe, J. L. (1986) A six-component chlorite solid solution model and the conditions of chlorite formation in hydrothermal and geothermal systems. Econ. Geol., 81, 681–703.Google Scholar
Windh, J. (1993, in press) Saddle-reef and related gold mineralization, Hill End Goldfield, Australia: Evolution of an auriferous vein system during progresive deformation. Ibid.Google Scholar