Sulfur and lead isotope geochemistry of the Liushutang lead-zinc deposit in Hu'nan Province and its significance

The discovery of the Liushutang lead-zinc deposit is one of the major breakthroughs of prospecting in the Nanling metal-logenic belt in recent years.The lead-zinc lodes are strictly controlled by the shattered fracture zones along the western margin of Hengyang basin.Field observation shows that the related mineralization can be divided into three stages of quartz-pyrite, quartzsphalerite-galena and barite.In this paper, systematic research on S, Pb isotopes based on different stages of ores were conducted to explain the origin of ore-forming materials and ore genesis.The result shows that sulfur isotopes of 17 sulfide samples vary in a wide range (δ³⁴S value being-12.8‰~4.6‰) with a dynamic evolution of gradual increasing of δ³⁴S values from early to late.This can be probably explained by a mixing process of organic sulfur (~-13‰) and magmatic sulfur (~5‰).Sulfur of latest barite ore (δ³⁴S is 14.7‰~24.4‰) might have been provided by the strata sulfate.²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, ²⁰⁸Pb/²⁰⁴Pb ratios of 13 sulfide ore samples vary in the range of 18.627~18.942, 15.670~15.804 and 38.366~38.912, with the average value being 18.747, 15.705 and 38.614, respec-tively.These values are very similar to values of Pb isotopes of magmatic feldspar in southern Hu'nan and also have weak linear rela-tion with Pb isotopes of regional Cambrian strata, suggesting that ore materials might have mainly originated from magmatic pluton in the depth, and subordinately from the Cambrian strata.Based on the above results and geological evidence, the authors put forward a model of magma-related hydrothermal mineralization with multiple sources of ore-forming materials, which may be suitable for explaining the ore genesis of the Liushutang deposit.