Genesis of upper proterozoic stratabound copper mineralization,Kapunda, South Australia

Chalcopyrite-rich bedded and vein mineralization at Kapunda occurs in two locally developed dolosiltstone units within a sequence of generally darker-coloured, finer-grained calcmudstones and siltstones. The Mine Series accumulated in shallow water to supratidal, sabkha-like environments; there is no evidence for igneous activity in the region. Isotope data for bedded sulphides are characteristic of biological sulphate reduction in a restricted basin. It is likely that iron sulphides were produced initially, and that copper was introduced subsequently in mildly oxidizing, highly saline groundwaters, the influence of which is seen in the ¹³C-¹⁸O correlation for dolomite in the mineralized siltstones. Isotopic data support derivation of the veins from their host sediments, and this appears to have occurred before lithification.