柴北缘双口山金-银-铅矿床赋矿围岩及含金石英脉热液锆石U-Pb定年对成矿时代的限定及其成因启示  

LA-ICP-MS zircon U-Pb age of the host rock and hydrothermal zircon in gold-bearing quartz vein of Shuangkoushan Au-Ag-Pb deposit,North Qaidam:limitation for the mineralization age and implication for the genesis of the deposit

作　　者：俞军真 郑有业[1,2] 许荣科 YU Junzhen;ZHENG Youye;XU Rongke(Faculty of Earth Resource,China University of Geosciences,Wuhan,430074;State Key Laboratory of Geological Processes and Mineral Resource,China University of Geosciences,Wuhan,430074;Geological Survey Institute,China University of Geosciences,Wuhan,430074)

机构地区：[1]中国地质大学(武汉)资源学院,武汉430074 [2]中国地质大学(武汉)国家重点实验室,武汉430074 [3]中国地质大学(武汉)地质调查研究院,武汉430074

出　　处：《地质学报》2020年第11期3361-3375,共15页Acta Geologica Sinica

基　　金：教育部长江学者和创新团队发展计划(编号IRT14R54);中央公益性基础地质调查项目(编号DD20190069)资助成果。

摘　　要：双口山金-银-铅矿床地处柴北缘西段,赋存在滩间山变基性-超基性变火山岩中。矿体由金矿体和银铅矿体组成,成矿作用与热液活动密切相关。本文通过对双口山含金矿体赋矿围岩及含金石英脉进行LA-ICP-MS锆石U-Pb年代学分析和研究。结果表明,赋矿围岩形成时代为443±2.9Ma,与区域滩间山群火山岩形成年代一致(440~490Ma)。含金石英脉热液锆石U-Pb年代为402.8±4.2Ma,与区域金矿床成矿年龄以及韧性剪切带年龄相接近(~400Ma),代表了金矿体热液作用及成矿时代。结合地质特征及前人研究,表明双口山金银铅矿床是柴北缘造山带在不同造山带演化阶段,由不同成矿作用,在不同时期,相互叠加形成的复合型多金属矿床。金矿体具有典型造山型金矿床特征的变质热液型金矿,其成因主要与造山运动过程中的变质和变形作用有关,成矿物质和流体来源于绿片岩相的滩间山群变基性-超基性变火山岩。银铅矿体为岩浆热液型,成矿与后碰撞造山作用伸展-构造转换有关的岩浆作用有关,成矿物质和流体来源于晚泥盆世深部含矿岩浆作用。The Shuangkoushan gold-silver-lead deposit is located in the western part of the North Qaidam,which is hosted in metamorphic basic-ultrabasic volcanic rocks of Tanjianshan Group.The deposit were composed of gold ore body and silver-lead ore body,and the mineralization is closely related to hydrothermal activity.In this study,we reported the age of the host rock and gold-bearing quartz veins in the gold-bearing ore body through the LA-ICP-MS zircon U-Pb geochronology analysis.It indicates that the formation age of host rock is 443±2.9 Ma,which is consistent with theVolcanic rocks of Tanjianshan group with an age range from 440 Ma to 490 Ma.The hydrothermal zircon U-Pb age of gold-bearing quartz vein is 402.8±4.2 Ma,which is close to the metallogenic age of gold deposits and ductile shear zone(~400 Ma)in local area,representing the hydrothermal action and mineralization age of the Shuangkoushan gold ore body.Together with the geological characters and previous researches,indicate that the gold ore body and silver-lead ore body are the products of different mineralization stage associated with different orogenic processes.The gold ore body can be classified as metamorphic-hydrothermal type and is genetically associated with orogenic metamorphism and deformation during the North Qaidam orogeny,with the gold and ore-forming fluids being sourced from greenschist facies metamorphic basic-ultrabasic volcanic rocks.The silver-lead ore body can be classified as intrusion-related magmatic-hydrothermal type and is genetically associated with magmatic activity at extensional faults in the post-orogeny period,with the silver,lead and ore-forming fluids being sourced from deep magmatism in late Devonian.

关 键 词：双口山 柴北缘 热液锆石 造山型金矿床 后碰撞造山 

分 类 号：P618.2[天文地球—矿床学]