Abstract
Further support for the view that mineralization at Mount Isa comprises two separate events is provided by 34S/32S measurement. Isotopic exchange between sulphides in lead-zinc-silver ores appears to have been promoted locally during metamorphism, whereas isotopic disequilibrium persists in the copper ores. These isotopic data are explained by a model in which sedimentary deposition of lead, zinc and silver was succeeded by the post-metamorphic emplacement of copper. Past biological activity is inferred from the occurrence of low concentrations of organic carbon with δ13C values ranging from −21 to −26‰ PDB. Carbonate contents, expressed as carbon, vary from <0.1% to 10.9%. The δ13C and δ18O values for the carbonates are relatively constant at −4.4±1.1‰ and −17.6±1.1‰ PDB respectively. These values are interpreted as reflecting isotopic changes induced in original marine carbonates by isotopic exchange during lower greenschist metamorphism.
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Smith, J.W., Burns, M.S. & Croxford, N.J.W. Stable isotope studies of the origins of mineralization at Mount Isa. I.. Mineral. Deposita 13, 369–381 (1978). https://doi.org/10.1007/BF00206570
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DOI: https://doi.org/10.1007/BF00206570