Fluid inclusion geochemistry of cloncurry (Fe)-Cu-Au deposits

摘要

High salinity fluid inclusions from Mesoproterozoic (Fe)-Cu-Au deposits in the Cloncurry district (NW Queensland) preserve evidence of different fluid types including various complex very high salinity Na-K-Ca-Fe-Mn+-Ba and lower salinity Na-Ca brines. Ore deposition occurred from spectrum of oxidized (hematite-stable, H_2O-CO_2) and reduced (pyrrhotite-stable, H_2O-CH_4+-CO_2) fluids. Cu- and Fe-rich primary magmatic brine inclusions have been identified at the Lightning Creek magnetite deposit and Br/Cl ratios in inclusions from the Cu-Au deposits are consistent with the dominantly magmatic fluid origin indicated from stable isotope evidence. Cu-contents of pre- to synmineralization inclusions vary from ca 100 ppm to ca 1.5