内蒙古阿扎哈达铜铋矿床流体包裹体和碳-氧-硫-铅同位素地球化学研究  

Fluid inclusion and C-O-S-Pb isotopic studies of the Azhahada Cu-Bi deposit in Inner Mongolia,China

作　　者：王银宏[1] 刘家军[1] 张梅[2] 张方方[1] 王康 咸雪辰 郭灵俊[2] WANG Yinhong;LIU Jiajun;ZHANG Mei;ZHANG Fangfang;WANG Kang;XIAN Xuechen;GUO Lingjun(State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Beijing 100083,China;Institute of Geological Survey of Inner Mongolia Autonomous Region,Huhhot 010020,Chin)

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]内蒙古自治区地质调查院,内蒙古呼和浩特010020

出　　处：《地学前缘》2020年第2期391-404,共14页Earth Science Frontiers

基　　金：国家重点研发计划项目(2017YFC0601202);国家自然科学基金项目(41772073,41572066,41702079);高等学校创新引智计划项目(BP0719021);内蒙古自治区地质勘查基金项目(2014-01-YS01)。

摘　　要：阿扎哈达石英脉型铜铋矿床位于二连-东乌旗多金属成矿带中段。铜铋热液矿化过程从早到晚可以分为3个阶段,分别为石英-黄铁矿-黄铜矿阶段(Ⅰ)、石英-黄铁矿-黄铜矿-辉铜矿-辉铋矿-自然铋-萤石阶段(Ⅱ)和晚期石英-方解石阶段(Ⅲ)。铜铋矿化主要产于Ⅱ阶段石英脉中。流体包裹体类型主要为气液两相包裹体。测温结果显示I阶段富气相包裹体均-温度变化范围为224~427℃,盐度(w(NaCleq)为16.0%~22.4%;富液相包裹体均-温度为229~410℃,盐度为9.2%~22.2%。Ⅱ阶段富气相包裹体均-温度为245~343℃,盐度为17.8%~20.5%;富液相包裹体均-温度为180~361℃,盐度为10.5%~21.3%。Ⅲ阶段富液相包裹体均-温度为132~262℃,盐度为3.4%~19.4%。成矿热液整体上属于中温、中等盐度流体。单个包裹体激光拉曼分析表明气液相成分主要是H2O,含少量CH4,指示成矿流体属于NaCl-H2O±CH4体系。C-O同位素数据(δ13CV-PDB值范围为-6.7‰^-1.4‰,δ18 OV-SMQW值为-2.4‰^+11.5‰)表明成矿流体主要来源于岩浆水,晚阶段有大气降水的混入。黄铁矿S同位素组成(1.3‰~9.5‰)指示成矿物质主要来源于岩浆热液,并有部分地层物质加入。黄铁矿Pb同位素组成208 Pb/204Pb、207Pb/204Pb和206 Pb/204Pb值变化范围分别为38.081~38.229、15.561~15.602和18.270~18.383,所有数据点均落在造山带铅范围内,表明成矿物质主要来源于侵位的花岗岩,同时地层提供了部分成矿物质。结合流体包裹体和同位素地球化学研究,文章认为温度下降及水岩反应是导致矿质沉淀的重要机制。The Azhahada quartz vein type copper-bismuth deposit is located in the middle segment of the Erlian-East Ujimqin polymetallic belt.Based on the fieldwork and microscope observations,as well as the mineral assemblages and crosscutting relationships of different veins,the hydrothermal mineralization of copper and bismuth at Azhahada has been divided into three stages from early to late:the quartz-pyritechalcopyrite early-stage I,the quartz-pyrite-chalcopyrite-chalcocite-bismuthinite-native bismuth-fluorite mainore stage Ⅱ,and the quartz-calcite late-stage Ⅲ.The copper and bismuth mineralization is mainly hosted in the stage Ⅱ quartz veins.The fluid inclusions at Azhahada are mainly composed of vapor-liquid two-phase inclusions.Microthermometric measurement results demonstrate that the vapor-rich inclusions in quartz of stage Ⅰ are homogenized at temperatures of 224-427℃,with salinities of 16.0%-22.4% NaCleq,whereas the liquid-rich inclusions are homogenized at 229-410℃,with salinities of 9.2%-22.2% NaCleq.In main ore stage Ⅱ,the vapor-rich and liquid-rich inclusions yield homogenization temperatures of 245-343 ℃,and 180-361℃,corresponding to salinities of 17.8%-20.5% NaCleq,and 10.5%-21.3% NaCleq,respectively.The liquid-rich inclusions in the quartz-calcite stage are homogenized at 132-262 ℃,with salinities of 3.4%-19.4% NaCleq.The ore-forming fluids are characterized by moderate temperature and moderate salinity.Laser Raman analyses of some individual representative inclusions suggest that their gaseous and liquid compositions are mainly H2 O,with trace amount of CH4;thus,the fluids are dominated by the NaCl-H2 O±CH4 system.The δ13CV-PDB values of calcite are in the range of-6.7‰ to-1.4‰,withδ18 OV-SMOW values from-2.4‰ to+11.5‰.Combined with the δ18O-δ13C plots,it is suggested that the ore-forming fluids were mainly derived from magmatic water,with the addition of meteoric water in the late stage.The δ38 SV-CDT values of pyrite are between 1.3‰ and 9.5‰,suggesting that the su

关 键 词：流体包裹体 C-O-S-Pb同位素 阿扎哈达铜铋矿床 内蒙古 

分 类 号：P618.41[天文地球—矿床学] P618.69[天文地球—地质学]