滇西笔架山锑矿床地质特征与流体包裹体研究

Geology and fluid inclusion of the Bijiashan Sb deposit in western Yunnan Province

滇西巍山笔架山锑矿床位于三江复合造山带之兰坪-思茅盆地中段，属于巍山-永平多金属成矿带的重要组成部分。矿体主要赋存在黑惠江背斜上三叠统碳酸盐岩-泥页岩建造中，矿体严格顺层产出。热液成矿期可进一步分为两阶段，Ⅰ阶段以发育辉锑矿与萤石为标志，此阶段为矿化主阶段；Ⅱ阶段发育萤石-石英-碳酸盐，无锑矿化；表生期发育次生氧化物锑华等。笔架山锑矿床脉石矿物中流体包裹体类型单一，以发育气液两相水溶液包裹体为主。Ⅰ阶段流体包裹体均一温度集中在145～185℃，Ⅱ阶段集中在125～155℃；各阶段流体显示中低盐度特征（多〈6% NaCleqv）。矿床地质特征、流体包裹体及同位素综合分析表明，笔架山锑矿床显示层控沉积-改造型热液矿床的特征，硫、锑成矿物质主要来自研究区上三叠统三合洞组和挖鲁八组地层，而与萤石沉淀有关的流体可能来源于地层建造水或盆地卤水与大气降水的混合。

The Bijiashan Sb deposit in the Weishan County, Yunnan Province, is located in the middle section of the Lanping-Simao basin in Sanjiang Orogeny, which belongs to the Weishan-Yongping polymetallic ore belt. The Sb orebodies are hosted in the Upper Triassic carbonate-shale formation of the Heihuijiang anticline and are strictly controlled by the strata occurrence. The hydrothermal ore-forming process can be divided into two stages, which are characterized by the fluorite-stibnite （stage Ⅰ） and fluorite-quartz-carbonate （stage Ⅱ） respectively, and the stage Ⅰ is the main mineralization stage. The valentinite is widely formed in supergene process. The fluid inclusions in fluorite and calcite are simple and dominated by NaCl-H2O solution. The homogenization temperatures of fluid inclusions in stage-Ⅰ and Ⅱ gangue minerals are concentrated at 145~185℃ and 125~155℃ respectively. The salinities of each stage are mainly less than 6%NaCleqv, showing it belongs to a medium-to-low temperature and salinity fluid system. The comprehensive researches on ore geological characteristics, fluid inclusion and isotope analysis show that the Bijiashan antimony deposit owns characteristics of stratabound sedimentary transformation type hydrothermal deposit. The sulfur, antimony metallogenic elements were mainly sourced from the Upper Triassic Sanhedong and Waluba formations, and the hydrothermal fluid related to the fluorite in stages Ⅰ and Ⅱ was probably a formation water or a mixture fluid system of basin brine water and atmospheric precipitation.