青海什多龙热液脉型钼铅锌矿床流体包裹体研究及矿床成因  

Fluids inclusion constraints on the origin of the Shiduolong hydrothermal vein-type Mo-Pb-Zn deposit, Qinghai Province

作　　者：李龚健[1,2] 王庆飞[1,2] 朱和平[3] 袁万明[1,2] 龚庆杰[1,2] 

机构地区：[1]中国地质大学,地质过程与矿产资源国家重点实验室,北京100083 [2]中国地质大学,岩石圈构造,深部过程及探测技术教育部重点实验室,北京100083 [3]中国科学院地质与地球物理研究所矿产资源研究重点实验室

出　　处：《岩石学报》2013年第4期1377-1391,共15页Acta Petrologica Sinica

基　　金：国家重点基础研究发展计划(2009CB421008);北京市优秀博士学位论文指导教师科技项目(20111141501);教育部长江学者和创新团队支持计划(PCSIRT);111计划(B07011)联合资助

摘　　要：什多龙热液脉型钼铅锌矿床受印支期成生的NNW向断裂构造控制,与该期构造运动导致的花岗岩类岩体的侵入活动紧密关联。热液成矿过程包括四个阶段,依次以石英-辉钼矿化(Ⅰ)、石英-黄铁矿-闪锌矿化(Ⅱ)、石英-多金属硫化物化(Ⅲ)及石英-碳酸盐化(Ⅳ)为特征。矿石石英中主要发育两类流体包裹体:富水的CO2-H2O两相包裹体与H2O溶液包裹体(包括富气相、富液相与纯液相三类)。Ⅰ阶段包裹体均一温度为317～397℃,盐度为9.98%～12.28%NaCleqv;Ⅱ阶段包裹体均一温度为226～342℃,盐度为4.34%～10.98%NaCleqv;Ⅲ阶段包裹体均一温度为131～247℃,盐度为2.07%～5.41%NaCleqv。流体叠加作用强烈,早阶段矿石石英中常见沿微裂隙捕获的晚阶段包裹体。流体包裹体气液相组分的分阶段热爆研究表明,成矿流体主要属于K+-Na+-SO42-型,从Ⅰ阶段至Ⅱ、Ⅲ阶段,阴阳离子总量急剧降低;气相组分除H2O与CO2外,还含有相对较多的N2、CH4等气体。Ⅰ阶段流体为混入了大气降水的岩浆水,Ⅱ阶段发生流体混合作用,大量大气降水与部分地层水混入流体系统中,Ⅲ阶段流体以大气降水及地层水为主。流体混合作用及伴随的温压条件的降低是导致铅锌等成矿元素沉淀与富集的重要机制。The Shiduolong hydrothermal Mo-Pb-Zn deposit is located in the Xinghai County, northeast of the Qinghai Province. Mineralization is controlled by NNW faults formed in the Indosinian, and closely associated with simultaneous granitoid intrusions. Four stages of hydrothermal ore-forming process are recognized, characterized by mineral assemblages of quartz-molybdenite （Ⅰ）, quartz-pyrite-sphalerite （Ⅱ）, quartz-polymetallic sulfides （Ⅲ） and quartz-carbonate （Ⅳ）, respectively. Two main types of fluid inclusions are distinguished in the hydrothermal quartz, aqueous-rich CO2-H2O inclusions and aqueous inclusions. The later can be further divided into vapor-rich, liquid-rich and pure liquid inclusions. Microthermometic data show that the homogenization temperatures of the fluid inclusions from the stage Ⅰto the Ⅲ are gradually decreased, from 317～397℃, through 226～342℃, to 131～247℃, and the corresponding salinities followed by 9.98%～12.28% NaCleqv, 4.34%～10.98% NaCleqv and 2.07%～5.41% NaCleqv. Plenty of secondary fluid inclusions could be observed in the quartz from the Ⅰand the Ⅱ stage, implying intensive fluid superposition subsequently. Study of gas-liquid components of fluid inclusions from different mineralization stages indicates that the ore-forming fluid belongs to K＋-Na＋-SO42- type, and the content of total ions reduced rapidly from early to late. The gas component contains a relatively high N2, CH4 and other gases in addition to H2O and CO2. The stage Ⅰ ore-forming fluid is mainly of magmatic water, hybrid with certain amount of meteoric water. Fluid mixing occurs in the stage Ⅱ, abundant meteoric water with some formation water mixed into the early stage fluid. Ore-forming fluid of the stage Ⅲ is mainly of meteoric water and/or formation water. Influence by surface water system is more and more obvious as the evolution of ore-forming fluid. The mixing of fluids and accompanying decrease of temperature and pressure are the dominant mechanisms for depos

关 键 词：什多龙铅锌矿区 热液脉型钼铅锌矿床 流体包裹体 气液相成分 成矿模式 

分 类 号：P611[天文地球—矿床学] P618.65[天文地球—地质学]