西拉沐伦钼矿带车户沟斑岩型钼-铜矿床成矿流体特征及其地质意义  

Characteristics and its geological significance of fluid inclusions in Chehugou porphyry Mo-Cu deposit,Xilamulun molybdenum metallogenic belt

作　　者：褚少雄[1,2] 曾庆栋[1] 刘建明[1] 张伟庆 张作伦[1,3] 张松 汪在聪[1,2] 

机构地区：[1]中国科学院地质与地球物理研究所矿产资源重点实验室,北京100029 [2]中国科学院研究生院,北京100039 [3]中铁资源集团有限公司,北京100039

出　　处：《岩石学报》2010年第8期2465-2481,共17页Acta Petrologica Sinica

基　　金：国家自然科学基金面上项目(40972065);国家危机矿山项目(20089931);国家"973"项目(2006CB403507)联合资助

摘　　要：车户沟钼-铜矿床是华北克拉通北缘西拉沐伦钼矿带上典型的斑岩型Mo-Cu矿床,位于华北克拉通北缘断裂南侧。矿床赋存于成矿母岩花岗斑岩及其围岩中,矿化类型以细脉浸染状矿化为主,还存在隐爆角砾岩型矿化和石英脉型矿化。根据脉体类型和矿物组合将车户沟钼-铜矿床划分为四个成矿阶段,分别为(1)辉钼矿-黄铁矿-石英阶段、(2)黄铜矿+黄铁矿±辉钼矿+石英阶段、(3)黄铁矿+石英阶段、(4)石英+碳酸盐±萤石阶段。成矿流体寄主矿物石英中发育Ⅰ型含CO2三相包裹体(LCO2+VCO2+LH2O)、Ⅱ型含子晶三相(V-L+S)包裹体、Ⅲ型富气相(V-L)包裹体、Ⅳ型富液相(L-V)包裹体、Ⅴ型纯气相(V)包裹体和Ⅵ型纯液相(L)六种类型。流体包裹体类型从早到晚具有规律性演化特征,表现为阶段(1)、(2)以发育Ⅰ型含CO2三相包裹体(LCO2+VCO2+LH2O)和Ⅱ型含子晶三相(V-L+S)包裹体为特征,成矿晚期阶段(3)、(4)以发育Ⅲ型富气相(V-L)包裹体、Ⅳ型富液相(L-V)水溶液包裹体为特征。从早阶段到晚阶段成矿流体温度及盐度具有规律性演化特征。均一温度峰值分别为270～400℃、230～370℃、160～290℃、120～230℃,成矿温度逐渐降低;流体盐度,阶段(1)流体盐度分两组:3.39%～14.25%NaCleqv和31.01%～>66.75%NaCleqv、阶段(2)流体盐度分两组:1.23%～12.85%NaCleqv和31.14%～64.33%NaCleqv、阶段(3)、(4)盐度分别介于1.05%～21.47%NaCleqv和2.07%～10.73%NaCleqv,盐度逐渐降低。激光拉曼显微探针(LRM)及群体包裹体成分分析结果表明,流体体系成分以H2O、CO2、Cl-、SO42-、Na+为主,贫F-、Ca2+、Mg2+为特征,特征离子比值暗示流体来源于岩浆流体。包裹体岩相学及包裹体测温表明,流体由早期的高温、高盐度、含二氧化碳NaCl-H2O-CO2体系岩浆流体在主成矿阶段(1)、(2)发生流体包裹体的沸腾作用和相分离,伴随流体沸腾、CO2逸失、温度降低等过程导致大量�Chehugou Mo-Cu deposit is a typical porphyry Mo-Cu deposit in the Xilamulun molybdenum metallogenic belt on the northern margin of North China Craton ( MNCC) . It locates to the south of the MNCC fault. The orebodies are mainly hosted in granite porphyry. The Mo mineralization is characterized by veinlet-disseminated mineralization as well as breccia type and quartz vein type mineralization. According to crosscutting relationships of different veins and mineral parageneses,ore-forming process can be divided into four stages: ( 1) the pyrite-molybdenite-quartz stage; ( 2) the pyrite -chalcopyrite-quartz ± molybdenite stage; ( 3) the pyrite- quartz stage; and ( 4) the quartz-carbonate ± fluorite stage. Petrographic study of fluid inclusions suggests that six dominant types of fluid inclusions related to metallogensis are present in the deposit: Ⅰ-Type CO2-bearing three-phase ( LCO2 + VCO2 + LH2O) ,Ⅱ-Type daughter-minerals bearing three-phase ( V-L + S) ,Ⅲ-Type gas-rich ( V-L) ,Ⅳ-Type liquid-rich ( L-V) ,Ⅴ-Type pure gas ( V) and Ⅵ-Type pure liquid ( L) phase inclusions. Types of fluid inclusions regulary evolves from the early stage to the late stage. Fluid inclusions in the first and the second stage are characterized with Ⅰ-Type CO2-bearing three-phase ( LCO2 + VCO2 + LH2O) and Ⅱ-Type daughter-minerals bearing three-phase ( V-L + S) inclusion. But in the later the third and the fourth stage which are characterized with Ⅲ-Type gas-rich ( V-L) and Ⅳ-Type liquid-rich ( L-V) inclusion. Homogenization temperatures and salinities of ore-forming fluid also regularly evolves from the early stage to the late stage. The peak value of Homogenization temperatures of different stages are separately 270 ～ 400℃,230 ～ 370℃,160 ～ 290℃,120 ～ 230℃,showing a reducing tendency from the early stage to the late stage; Fluid salinities of the first stage could subdivide into two groups: 3. 39% ～ 14. 25% NaCleqv and 31. 01% ～ > 66. 75% NaCleqv. Fluid salinities of the second stage also could be su

关 键 词：西拉沐伦钼矿带 斑岩型钼-铜矿 流体包裹体 车户沟 内蒙古 

分 类 号：P618.41[天文地球—矿床学]