A lead-isotope study of the Pb-Zn-Cu deposit at Woodlawn, New South Wales

In the massive sulphide ore of the Woodlawn Pb-Zn-Cu deposit, lead isotopic ratios of pyrite, galena, sphalerite, and chalcopyrite are uniform (206Pb/204Pb 18.089, 207+Pb/204Pb 15.605, 208Pb/Pb204 38.106) and are the same as the initial lead ratios in pyrite from the host volcanics. Pyrite from the footwall appears to be more radiogenic in 206Pb and 208Pb, and to have lower Pb concentrations than those in the hanging wall. Initial lead ratios in the whole rock volcanics are the same as those in the ore, thus suggesting a common source for the lead. Lead isotopic data for the gossan minerals are the same as for the primary sulphides; this demonstrates that no isotopic fractionation or contamination by radiogenic lead occurred during oxidation of the primary ore.