青海湟中县三岔金矿流体包裹体特征及矿床成因  

Fluid Inclusions Characteristecs and Ore Genesis of Sancha Gold Deposit in Huangzhong County,Qinghai Province

作　　者：张延军[1] 孙丰月[1] 李碧乐[1] 李良[1] 陈扬[1] 

机构地区：[1]吉林大学地球科学学院,长春130061

出　　处：《吉林大学学报（地球科学版）》2016年第5期1342-1353,共12页Journal of Jilin University：Earth Science Edition

基　　金：国家自然科学基金项目(41272093);中国地质调查局地质大调查项目(12120110860202)~~

摘　　要：三岔金矿位于中祁连新元古代-早古生代中晚期岩浆弧带，是一个陆块与岩浆弧叠置的构造单元。本文在详细的野外矿床地质研究的基础上，开展了与金成矿密切相关的各期流体包裹体岩相学、显微测温、包裹体成分的LRM、碳-氢-氧同位素等方面的分析对比研究工作。结果表明：早期成矿阶段的隐爆石英角砾岩流体包裹体发育气液两相、含子矿物三相和富液相CO2包裹体，均一温度集中于200～280℃，盐度（w（NaCl））集中于6.00%～18.00%，密度集中于0.64～0.73 g/cm^3；主成矿阶段的黄铁绢英岩主要发育气液两相包裹体，均一温度集中于160～240℃，盐度为2.00%～6.00%，密度为0.80～0.95 g/cm^3；晚期的石英脉阶段主要发育气液两相包裹体，均一温度主要集中在120～190℃，盐度为2.00%～6.00%，密度为0.76～0.86 g/cm^3。碳-氢-氧同位素组成揭示三岔矿床的成矿流体早期主要以岩浆水为主，至演化后期，成矿流体有大气水加入；硫同位素研究反映了成矿物质深源性特征。因此，认为三岔矿床属中温热液脉型矿床。Sancha mining area located Qilian landmass among Qilian orogenic belt, which is a landmass and magmatic arc stacked construction units. It is Neoproterozoic-Early Paleozoic of middle-late stage magmatic arc, sandwiched between North Qilian suture zone and Shulenan Mountain-Laji Mountain suture zone. Based on detailed studies of field deposit geology, through petrography, microthermometry analysis, inclusions constituents LRM analysis, carbon-hydrogen-oxygen isotope analysis and comparison research on the fluid inclusions of each stage closely associated with ore-forming fluids, the results showed that： cryptoexplosive quartz breccia of early mineralization stages has three types fluid inclusions, i.e. gas-liquid two-phase inclusions, daughter minerals-bearing three-phase inclusions and liquid-rich CO2 inclusions. Its homogenization temperatures concentrates in the range of 200-280℃, salinity in the range of 6.00%-18.00% NaCleqv, density in the range of 0.64-0.73 g/cm^3. Pyrite phyllic of the main mineralization stage and Quartz veins of late stage mainly has one type fluid inclusions, i.e. gas-liquid two-phase inclusions. The main mineralization stage homogeneous temperature varies from 160 to 240℃, salinity from 2.00% to 6.00% NaCleqv, density from 0.80 g/cm^3 to 0.95 g /cm^3. Late stage homogenization temperatures concentrates in the range of 120-190℃, salinity in the range of 2.00%-6.00% NaCleqv, density in the range of 0.76-0.86 g/cm^3. Carbon-hydrogen-oxygen isotopic composition reveals early ore-forming fluid of Sancha deposits is mainly magmatic water. In the late stage of the evolution, ore-forming fluid is obviously involved the meteoricwater, and sulfur isotope studies reflect that ore-forming material has characteristics of deep source. Therefore, Sancha gold deposit genetic type is mesothermal vein-type deposit.

关 键 词：三岔金矿 热液脉型 地质构造 流体包裹体 青海 

分 类 号：P618.51[天文地球—矿床学]