A Fluid Inclusion and Isotopic Study of the Mineralization in the Zinc-Rich Burketown Mineral Field, Northern Australia

Abstract

The ca. 1575 Ma Century Zn-Pb deposit and the 47 near-by discordant Zn-Pb lode deposits of the Burketown Mineral Field, northern Australia host ore and gangue minerals that have not been overprinted by deformation associated with the the 1610?1520 Ma Isan Orogeny (Page and Bell, 1986; Blake, 1987), which obliterated many of the primary textural features at the Mt Isa, Hilton and George Fisher deposits. The Burketown Mineral Field deposits, which are hosted in shales and siltstones belonging to the Isa Superbasin, comprise sphalerite, pyrite, carbonate, quartz, galena, chalcopyrite and minor illite that lend themselves to isotopic and fluid inclusion studies that cannot be performed on the deposits to the south. For instance, there are no published O-H isotopic data from any of the known Zn-Pb deposits in the Mt Isa Basin and very limited, pre-Isan 40Ar/39Ar and fluid inclusion data (Rohrlach et al., 1998). A paragenetic and isotopic study of Century and 14 of the discordant lode deposits combined with published Pb/Pb model ages reveal that multiple fluid events spanning a period lasting ca. 400 million years since the initial formation of the Century deposit are preserved in this area.