云南会泽铅锌矿田硫同位素研究

Sulfur Isotopic Geochemistry of the Huize Pb-Zn Ore Field in Yunnan Province

为探讨会泽铅锌矿田成矿流体总硫同位素组成、成矿温度、硫源及还原硫的形成机制,在分析前人的硫同位素数据基础上对麒麟厂矿床上部原生矿体硫化物（黄铁矿、闪锌矿和方铅矿）及麒麟厂和矿山厂矿床外围新发现的硫酸盐矿物（重晶石）进行了硫同位素研究。结果显示,原生矿体中的硫化物的δ34S变化为8.0‰-17.68‰,成矿流体中硫同位素已达分馏平衡;矿床外围的硫酸盐δ34S变化为17.95‰-24.30‰。利用共生矿物对Pinckney法,估算获得成矿流体的δ34SΣS为14.44‰,与海相硫酸盐的δ34S相近;通过同位素地质温度计,估算获得成矿温度为134-388℃;包裹体测温发现,重晶石为热液成因,暗示成矿流体中的硫可能来自矿区及矿区外围各个地层的海相硫酸盐或是矿区发现的热液重晶石。硫酸盐的还原机制应为热化学还原作用（TSR）。

In order to constrain sulfur isotope compositions of ore-forming fluids,ore-forming temperature,source of sulfur and mechanism of sulfur reduction in the Huize lead-zinc ore field,based on sulfur isotope compositions from previous studies,new data of sulfur isotopic composition of primary sulfide of upper ore-bodies in Qilinchang and newly-found sul-fate outside the deposits were utilized in this study.It show thatδ^34Svalues of primary sulfide vary from 8.0‰ to 17.68‰, and sulfur isotopes in ore-forming fluid have reached equilibrium;δ^34Svalues of sulfur out side the deposits vary from 17.95‰ to 24.30‰ with average value of 20. 14‰,yielding sulfur isotopic composition of ore-for ming fluids as14. 14‰by the Pinckney method for mineral association.The value is close to δ^34Sof marine sulfate.Ore-forming temperature is calculated as 134-388℃ by isotope geological thermometer.The results of fluid inclusion thermometer indicate that barites were crystallized from hydrothermal fluid,which is suggested that sulfur in ore-forming fluid probably originates from ma-rine sulfate of stratum in and outside the deposits or hydrothermal barites found in ore district.Reduction mechanism of sulfate is likely to be thermo-chemical sulfate reduction.