藏南扎西康矿集区姐纳各普金矿床地质与流体包裹体特征  

A Study on Ore Geological Characteristics and Fluid Inclusions of Jienagepu Gold Deposit in Zhaxikang Ore Concentration District, Southern Tibet, China

作　　者：李洪梁[1,2] 李光明[1,2] 李应栩[2] 董随亮[2] 卿成实[2] 付建刚[2,3] 刘洪[2] 黄瀚霄[2] 

机构地区：[1]成都理工大学地球科学学院,四川成都610059 [2]中国地质调查局成都地质调查中心,四川成都610081 [3]中国地质大学(北京)地球科学与资源学院,北京10083

出　　处：《矿物学报》2017年第6期684-696,共13页Acta Mineralogica Sinica

基　　金：科技部深地资源勘查开采项目;冈底斯-喜马拉雅铜矿资源基地调查项目(编号:DD20160015);中国地质调查局地质调查项目(编号:1212010918033;12120115022801;12120113036000;12120114068501)

摘　　要：姐纳各普金矿床位于藏南金锑成矿带东段,是近年来在扎西康矿集区内新发现的岩金矿床。矿床产于蚀变辉绿岩中,矿体受北西-南东向韧脆性断裂及层间破碎带控制。矿石类型有蚀变岩型和石英脉型2种,呈网脉状、角砾状及定向构造,土状、结晶、碎裂、糜棱结构;矿石中金属矿物主要为黄铁矿、毒砂、辉锑矿、方铅矿、闪锌矿及自然金,脉石矿物以石英、绢云母及绿泥石为主;围岩蚀变主要为黄铁绢英岩化和绿泥石化;据脉体穿插和矿物共生组合,将原生热液成矿期分为石英-黄铁矿(早)、石英-金-贱金属硫化物(中)和石英-碳酸盐矿物(晚)3个阶段。对矿石中石英流体包裹体研究显示,矿床主成矿阶段(中)流体包裹体主要为由纯CO_2、水溶液和富CO_2-水溶液流体包裹体3种所构成的非均一捕获流体包裹体组合(F.I.A.),均一温度为221.7~279.4℃,盐度为1.57%~6.74%,流体密度为0.58~0.88 g/cm^3,属中低温、低盐度、低密度、富CO_2的H_2O-Na Cl-CO_2±CH_4±N_2体系。主成矿阶段内见均一温度相近的不同类型包裹体和同类型具不同气液比的包裹体共存于同一视域,显示成矿流体的不混溶性,成矿温度为218.6~280.4℃,成矿压力为73~93 MPa。据成矿压力估算得成矿深度为5.8~7.9 km,成矿时的地温梯度为35~45℃/km。矿床地质特征及成矿流体性质表明,姐纳各普金矿床为与岩浆或岩浆热液活动有关的造山型金矿床,成矿与中新世印度—欧亚大陆碰撞挤压向伸展作用的转换有关。Jienagepu gold deposit, a newly discovered gold deposit in Zhaxikang Ore Concentration District in recent years, is located in the eastern part of Southern Tibetan gold-antimony metallogenic belt. Jienagepu gold deposit is hosted in altered diabase. The ore bodies are mainly controlled by ductile-brittle faults and interlayer fracture zones with northwest-southeast stretch. Two different kinds of ore types are identified as altered rock type and quartz vein type, characterized by mesh-vein, brecciated and oriented structure, amorphous, crystal, cataclastic and mylonitic texture. Ore minerals are dominantly comprised of pyrite, arsenopyrite, stibnite, galena, sphalerite and native gold, while the gangue minerals are mainly quartz, sericite and chlorite. Wall rock alterations mainly include beresitization and chloritization. According to the intercalation relationships of different veins and paragenetic associations of minerals, primary hydrothermal ore-forming period can be divided into 3 stages, namely, quartz-pyrite stage（early）, quartz-gold-base metal sulfides stage（middle） and quartz-carbonate minerals（late）. Primarily study on the fluid inclusions of quartz in ore shows that the main fluid inclusions of Jienagepu gold deposit in main metallogenic（middle） stage are pure CO2, aqueous and rich CO2-aqueous fluid inclusions, which constitute a fluid inclusion association（F.I.A） trapped in non-homogenized condition. The homogenization temperatures, salinities and densities of fluid inclusions range from 221.7 to 279.4 ℃, 1.57% to 6.74%, and 0.58 to 0.88 g/cm^3, respectively, belonging to the H2 O-Na Cl-CO2±CH4±N2 system, and are characterized by the medium-low temperature, low salinity, low density and rich CO2. There are always many different types of inclusions and same types of inclusions with different gas/liquid ratios in a vision in middle stage, and the homogenization temperatures of those inclusions are similar, which shows that the ore-forming fluid is immiscible. The metallogenic t

关 键 词：造山型金矿 矿床地质 流体包裹体 扎西康矿集区 藏南 

分 类 号：P579[天文地球—矿物学] P618.51[天文地球—地质学]