Zinc, sulfur and cadmium isotopes and Zn/Cd ratios as indicators of the origin of the supergiant Broken Hill Pb–Zn–Ag deposit and other Broken Hill-type deposits, New South Wales, Australia

Abstract Various genetic models have been proposed for the supergiant Proterozoic Broken Hill Pb–Zn–Ag deposit largely based on geological and geochronological evidence. Here we present Zn, Cd S isotope compositions as well Zn/Cd ratios of sphalerite from minor Hill-type deposits (Australia) to help constrain these but focus syngenetic magmatic–hydrothermal processes, since epigenetic can be rejected because orebodies were deformed metamorphosed by Olarian Orogeny. Values δ 34 VCDT , 66 Zn AA-ETH 114 NIST SRM 3108 range +0.27 +4.73 ‰, −1.15 +0.46 ‰ −0.48 +0.01 respectively, while those smaller −5.11 +1.28 −0.97 +0.10 −1.02 +2.59 respectively. By combining published data sulfides district with obtained here, sources sulfur via thermochemical sulfate reduction, bacterial reduction a magmatic origin cannot distinguished. However, when are considered along broad sphalerite, which among lightest heaviest yet reported sulfide deposit, isotopic datasets consistent low-temperature biogenic processes associated deposition sulfides. Cadmium coupled previously used classify Pb–Zn deposits, including low-temperature, high-temperature exhalative ores. such classification purposes.