四川乌斯河铅锌矿床成矿流体特征及TSR作用初探  

Ore-Forming Fluid and Thermochemical Sulfate Reduction in the Wusihe Lead-Zinc Deposit,Sichuan Province,China

作　　者：熊索菲[1,2] 姚书振[1] 宫勇军[1] 谭满堂[3] 曾国平[1] 王伟[1] 

机构地区：[1]中国地质大学资源学院,湖北武汉430074 [2]中国地质大学紧缺矿产资源勘查协同创新中心,湖北武汉430074 [3]中国地质调查局武汉地质调查中心,湖北武汉430200

出　　处：《地球科学（中国地质大学学报）》2016年第1期105-120,共16页Earth Science-Journal of China University of Geosciences

基　　金：中国地质调查局项目(No.12120113094200)

摘　　要：四川乌斯河铅锌矿床是赋存于震旦系灯影组白云岩中的大型铅锌矿床.本次研究结合最新的野外地质现象发现该矿床除存在前人所强调的沉积成矿作用以外,热液成矿作用非常明显.对该矿床流体包裹体进行细致的岩相学、显微测温和激光拉曼研究,揭示成矿流体特征,并探讨成矿机制.研究结果显示该矿床包裹体类型较为单一,以气液两相为主,均一温度主要集中于120~260℃,平均盐度为10.0%NaCl eqv,压力为32~68MPa,成矿流体为中-低温、中等盐度.激光拉曼测试显示包裹体气相成分含有CH_4、H_2S、C_2H_6、C_2H_2、N_2和NH_3,为多元共存的流体体系.在热驱动力下(120~260℃),流体混合作用提供了物质基础(SO_4^(2-))、催化剂(Mg^(2+))和还原剂(有机质、CH_4和H_2S)促使硫酸盐热化学还原反应(TSR)启动.TSR反应过程中流体pH发生变化,进一步促进了金属硫化物沉淀.The Wusihe lead-zinc deposit, hosted in the Dengying Formation, is a large lead-zinc deposit in the Sichuan Province, China. The previous research noted the Wusihe deposit was classified as a sediment-hosted stratiform lead-zinc deposit. However, our field survey result suggests that hydrothermal ore-forming processes are crucial to lead-zinc mineralization. In this pa- per, we present a detailed petrographic, microthermometric and laser Raman spectroscopy study of fluid inclusions from the Wusihe deposit reveals the characteristics of ore-forming fluids and mineralization mechanism. Primary fluid inclusions （FIs） in dolomite, quartz, calcite, fluorite and sphalerite are mainly two phases （L＋V type）. Microthermometric data show the hom- ogenization temperatures range from 120 ℃ to 260 ℃, and the average of salinity is 10.0%NaCl eqv. The estimated trapping pressures are 32 MPa to 68 MPa. The laser Raman spectroscopy shows that the gas components have a certain amount of CH4, H2S, C2H6, C2H2, N2 and NH3. The mixed ore-forming fluids offer heat, SO4^2- , and Mg^2＋ to provoke the thermochemical sulfate reduction （TSR）. The TSR could be a key factor for sulfur source and H^＋. The change of pH value leads to the precipitation of metallogenic elements.

关 键 词：成矿流体 流体包裹体 铅锌矿 TSR作用 地球化学 

分 类 号：P588.12[天文地球—岩石学] P595[天文地球—地质学]