湖南锡田钨锡多金属矿床流体包裹体研究  

Fluid inclusion studies of Xintian tin-tungsten polymetallic deposit in Hunan Province

作　　者：刘曼[1,2] 邱华宁[1] 白秀娟[3] 肖明[1,2] 何立言[1,2] 

机构地区：[1]中国科学院广州地球化学研究所,广东广州510640 [2]中国科学院大学,北京100049 [3]中国地质大学(武汉),湖北武汉430074

出　　处：《矿床地质》2015年第5期981-998,共18页Mineral Deposits

基　　金："973"项目"华夏地块中生代陆壳再造与巨量金属成矿(编号:2012CB416706)";国家自然科学基金创新群体项目"岩浆过程中元素的地球化学性质与成矿(编号:41421062)"的联合资助

摘　　要：锡田钨锡多金属矿床是南岭钨锡成矿带的重要组成部分。文章主要针对石英脉型钨锡矿和云英岩型钨矿中的石英流体包裹体进行了显微测温和激光拉曼光谱分析，流体包裹体分为4类：富液相两相水溶液包裹体（L型）、富气相两相水溶液包裹体（V型）、Vco2-Lco2-LH2O三相包裹体（C型）和含子晶三相包裹体（S型）。石英脉型钨锡矿均一温度为240～440℃，w（NaCLm）为1．4％～9．5％，云英岩型钨矿均一温度为370～470℃，且富锡石样品均一温度（th：310～420℃，w（NaCleq）为4．3％～9．5％）略高于富黑钨矿样品（th：240～340℃，w（NaCleq）为1．4％～7．7％）。流体包裹体气相成分主要为C02、C地、№。结合流体包裹体显微测温、激光拉曼光谱分析结果和野外矿床地质特征，探讨了成矿流体中N2、CH4的源区、w和Sn的赋存状态以及其成矿机制。W以一系列钨酸、钨酸根离子、碱金属钨酸盐赋存于流体中，Sn主要赋存状态为Sn（＋2价）-Cl络合物。石英脉型钨锡矿因流体上升至花岗岩体或围岩的构造裂隙中，成矿流体与围岩相互反应以及与地壳流体与大气水混合，其小t急剧下降以及流体pH值变化，导致黑钨矿沉淀，成矿流体从还原环境转为氧化环境致使锡石沉淀成矿。云英岩型钨矿有效成矿机制是流体沸腾或不混溶。The Xitian tin-tungsten polymetallic deposit is an important deposit in the Naling metallogenic belt. In this study, the authors analyzed the fluid inclusions in quartz and fluorites from the tin-tungsten quartz veins and wolframitebearing greisen orebodies by using such techniques as microthermometry and laser Raman spec- troscopy. Fluid inclusions can be mainly divided into four types： ① liquid-rich two-phase aqueous inclusions （Type L）; ② gas-rich two-phase aqueous inclusions （Type V）;③ CO2-bearing three-phase inclusions （Type C） and ④ daughter-mineral-bearing three-phase inclusions （Type S）. Microthermometric analyses indicate that the homogenization temperatures of quartz-vein type tungsten-tin ore vary from 240 to 440℃, and those of the greisen type wolframite ore from 370 to 470℃. The laser Raman analyses show that the main gas components of the ore-forming fluids consist of CO2, CH4, N2. Based on these data, the authors probed into the source region of N2, CH4 and the modes of occurrence of W and Sn in the ore-forming fluids, and discussed the metallogenic mechanism. Tungsten transport in ore-forming solutions occurred in the forms of tungstate ions, sodium tungstate, tungstic aeid, or heteronuelear acid. However, tin transport was affected by a complex series of stan- nous chloride-bearing species （Sn （ ＋ 2）-（21）. Ore-forming fluid moved upward into structural fractures in granitic masses or wall rocks due to the interaction of the ore-forming fluid with wall rocks and the mixture of crust-derived fluids or meteoric water, and then the pressure and temperature of ore-forming fluid sharply de- creased, accompanied by the change of pH values, which led to the formation of quartz-vein type tungsten-tin deposits. Effective metallogenic mechanism of greisen-type tungsten deposits might be fluid boiling or fluid im-miscibility.

关 键 词：地球化学 流体包裹体 显微测温 激光拉曼光谱分析 石英脉型钨锡矿 云英岩型钨矿 锡田钨锡多金属矿床 

分 类 号：P618.67[天文地球—矿床学] P618.44[天文地球—地质学]