青海省曲麻莱县大场金矿床成矿流体演化:来自流体包裹体研究和毒砂地温计的证据  

Ore-forming fluid evolution of Dachang gold deposit in Qumalai County, Qinghai Province: Evidence from fluid inclusion study and arsenopyrite geothermometer

作　　者：丁清峰[1,2] 王冠[1] 孙丰月[1] 张本龙[1] 金圣凯[1] 

机构地区：[1]吉林大学地球科学学院,长春130061 [2]南京大学地球科学与工程学院,内生金属矿床成矿机制研究国家重点实验室,南京210093

出　　处：《岩石学报》2010年第12期3709-3719,共11页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(40802021);吉林大学基本科研业务费专项(421030454422);中国科学院地球化学研究所矿床地球化学国家重点实验室开放研究基金(200906)联合资助

摘　　要：通过详尽的野外调研和室内研究,本文简要总结了大场金矿床的矿床地质特征。结合流体包裹体显微测温和毒砂地温计,认为大场金矿成矿阶段由早到晚可划分为贫矿化石英阶段、石英硫化物阶段、石英辉锑矿阶段、含明金石英阶段和石英方解石阶段共五个阶段,其中前四个阶段分别形成贫矿化石英脉(成矿温度350℃左右,均一温度为280~360℃)、金-石英-硫化物碎裂岩型矿石(成矿温度301℃左右,均一温度为220~280℃)、金-石英-辉锑矿型矿石(均一温度为160~220℃)和明金-石英脉型矿石(均一温度为160~220℃),最晚的石英方解石阶段则使先前形成的四类岩/矿石发生轻微硅化和方解石化蚀变(均一温度小于160℃)。结合流体包裹体激光拉曼光谱分析,认为大场金矿成矿流体经历了早阶段静岩压力系统(成矿压力为215MPa,成矿深度8.1km)下的低盐度H2O-CO2-NaCl体系,中阶段静岩向静水压力过度系统(成矿压力为49~108MPa,成矿深度5.5~8.6km)下的低盐度H2O-NaCl体系,以及晚阶段静水压力系统(估计成矿压力小于40MPa)下的低盐度H2O-NaCl体系。最后认为,大场金矿床的成因类型属于中浅成造山型金矿床。Local geology of Dachang gold deposit was summarized simply according to detailed fieldworks and indoor researches Based on microthermometic analyses of fluid inclusion, it was considered that metallogenic stages could be divided into poor mineralized quartz, quartz sulfide, quartz stibnite, visible-gold-bearing quartz and quartz calcite ones early and late Poor mineralized quartz veins (metallogenic temperatures are about 350℃, and homogenization temperatures are 280~360℃), native-gold-quartz-sulfide cataclastic ores (metallogenic temperatures are about 301℃, and homogenization temperatures are 220~280℃), gold-quartz-stibnite ores (homogenization temperatures are 160~220℃), and native-gold-quartz veins (homogenization temperatures are 160~220℃), formed respectively in the former four stages, and little silicification and carbonification (homogenization temperature is lower than 160℃) could happen in the above four types of rocks or ores during the latest quartz calcite stage Accompany with Laser Raman spectrum analyses, it was concluded that the metallogenic fluids underwent low salinity H2O-CO2-NaCl fluid system in lithostatic pressure system (metallogenic pressure is 215MPa, metallogenic depth is 81km) in the early stage, low salinity H2O-NaCl fluid system in lithostatic to hydrostatic pressure system (metallogenic pressures are 49~108MPa, metallogenic depths are 55~86km) in the middle stage and low salinity H2O-NaCl fluid system under hydrostatic pressure system (metallogenic pressures may be low than 40MPa) in the latest stage, respectively Finally, the author thought the genetic type of Dachang gold deposit belongs to epizonal to mesozonal orogenic gold deposit

关 键 词：流体包裹体 毒砂地温计 中浅成造山型金矿床 大场金矿 青海 

分 类 号：P618.51[天文地球—矿床学]