江南造山带中段井冲钴铜矿床成矿时代、流体性质与成矿模式  

Mineralization Age,Fluid Properties,and Metallogenic Model of the Jingchong Co-Cu Deposit in the Central Jiangnan Orogen,South China

作　　者：陕亮 王川[3] 康博 姜军胜 王力 张鲲 李艳军 SHAN Liang;WANG Chuan;KANG Bo;JIANG Junsheng;WANG Li;ZHANG Kun;LI Yanjun(Wuhan Center,China Geological Survey/South China Innovation Center for Geosciences,Wuhan 430205,Hubei,China;Research Center of Granitic Digenesis and Mineralization,China Geological Survey,Wuhan 430205,Hubei,China;School of Earth Resources,China University of Geosciences(Wuhan),Wuhan 430074,Hubei,China;Institute of Geological Hazard Investigation and Monitoring,Hunan Geological Academy,Changsha 410027,Hunan,China;Survey Institute of Resources and Environment of Hainan Province,Haikou 570206,Hainan,China)

机构地区：[1]中国地质调查局武汉地质调查中心(中南地质科技创新中心),湖北武汉430205 [2]中国地质调查局花岗岩成岩成矿地质研究中心,湖北武汉430205 [3]中国地质大学(武汉)资源学院,湖北武汉430074 [4]湖南省地质院地质灾害调查监测所,湖南长沙410027 [5]海南省资源环境调查院,海南海口570206

出　　处：《大地构造与成矿学》2024年第6期1299-1314,共16页Geotectonica et Metallogenia

基　　金：中国地质调查局花岗岩成岩成矿地质研究中心开放基金重点项目(PM202301);湖北省自然科学基金项目(2020CFB725);中央高校基本科研业务费项目(CUGCJ1817)联合资助。

摘　　要：江南造山带中段井冲钴铜矿床是我国少见的以钴为主的矿床之一,但其成矿时代、流体性质与成矿模式研究相对薄弱。本文基于井冲钴铜矿床地质特征,通过与钴铜共生的黄铁矿Rb-Sr等时线法厘定钴铜成矿阶段成矿年龄为128.3±2.7 Ma。流体包裹体测温、流体成分及H-O同位素等研究确定主成矿阶段石英中成矿流体主要为中温、中低盐度、低密度的NaCl-H_(2)O体系,为岩浆水与大气降水混合。流体混合及温度降低是成矿物质沉淀的重要因素。结合成岩时代、成矿流体来源等相关研究成果,综合确定井冲钴铜矿床为与连云山岩体晚期侵位(129 Ma±)有关的中温岩浆热液型矿床,并构建了该矿床早白垩世时期(125~130 Ma)岩浆-构造-流体“三位一体”耦合成矿模式。The Jingchong cobalt-copper deposit is located in the central Jiangnan Orogen,South China.It is one of the cobalt-dominated magmatic-hydrothermal vein deposits in China.However,its mineralization age,fluid properties,and metallogenic model are poorly defined.In this study,we present the results of pyrite Rb-Sr dating,fluid inclusions,and H-O isotopic compositions and propose a metallogenic model for the Jingchong Co-Cu deposit.Five fine-grained pyrite separates from the main mineralization stage of the deposit yielded a Rb-Sr isochron age of 128.3±2.7 Ma(MSWD=2.0),indicating that the Co-Cu mineralization occurred during the Early Cretaceous.This age is coeval with the previously reported U-Pb age of the late stage of the Lianyunshan granite,suggesting a close link between the Co-Cu mineralization and the magmatism.Fluid inclusions within quartz associated with Co-Cu mineralization are dominated by liquid-rich phase with homogenization temperatures of 134-305℃(dominated by 200-225℃)and salinities of 0.35%-11.70%NaCl_(eqv).The compositions of the fluid inclusions suggest that the ore-fluid fluids are dominated by the NaCl-H_(2)O system with less Na_(2)SO4-CaSO_(4)-NaCl-H_(2)O system.H-O isotopic compositions of the quartz samples indicate that the ore-forming fluids were dominated by magmatic fluids,with the involvement of meteoric water in the late stage of Co-Cu mineralization.Therefore,the decrease in temperature and fluid mixing might have led to the precipitation of ore-forming metals such as Co,Cu,and Zn.We,therefore,propose that the formation of the Jingchong Co-Cu deposit was associated with magmatic-hydrothermal activities of the late-stage magmatism(129 Ma±)of the Lianyunshan granitic complex.

关 键 词：钴铜矿床 早白垩世 岩浆热液型 成矿模式 井冲 

分 类 号：P611[天文地球—矿床学]