湘东北万古金矿田江东金矿床成因——流体包裹体和H-O同位素制约  

Genesis of Jiangdong Gold Deposit in Wangu Gold Field,Northeast Hunan:Constraints from Fluid Inclusions and H-O Isotope

作　　者：袁梓焜 邵拥军 刘清泉[1,2,3] 张毓策[1,2,3] 王智琳 YUAN Zikun;SHAO Yongjun;LIU Qingquan;ZHANG Yuce;WANG Zhilin(Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring(Central South University),Ministry of Education,Changsha 410083,Hunan,China;Key Laboratory of Non-ferrous and Geological Hazard Detection,Changsha 410083,Hunan,China;School of Geosciences and Info-Physics,Central South University,Changsha 410083,Hunan,China)

机构地区：[1]有色金属成矿预测与地质环境监测教育部重点实验室(中南大学),湖南长沙410083 [2]有色资源与地质灾害探测湖南省重点实验室,湖南长沙410083 [3]中南大学地球科学与信息物理学院,湖南长沙410083

出　　处：《黄金科学技术》2024年第4期559-578,共20页Gold Science and Technology

基　　金：湖南省科技创新计划项目“关键金属资源勘查创新团队”(编号:2021RC4055);湖南黄金集团项目“湘东北万古金矿田构造控矿体系、成矿规律及找矿预测研究”联合资助。

摘　　要：万古地区金矿床成矿流体的性质、来源和演化以及矿床成因类型尚存在争议。本次选择万古地区的江东金矿床,系统开展了不同阶段石英的SEM-CL分析、流体包裹体显微测温、激光拉曼光谱分析以及H-O同位素测试。流体包裹体测试结果表明,成矿流体由中温、中—低盐度的H_(2)O-NaCl-CO_(2)体系逐渐演化为中—低温、中—低盐度的H_(2)O-NaCl体系。H-O同位素测试结果表明:岩浆流体是主要的成矿流体来源,可能来源于燕山期的岩浆活动。金在成矿流体中主要以Au(HS)_(2)^(-)形式运移,流体不混溶作用和水—岩反应可能是金沉淀的主要机制。综合江东金矿床地质特征、流体包裹体特征和H-O同位素研究结果,认为其属于与岩浆活动有关的岩浆热液型金矿床。The debate surrounding the source,properties and evolution of ore-forming fluids and the genesis of gold deposits in the Wangu area are still remains unresolved.To address this issue,the present study focuses on the Jiangdong gold deposit within the Wangu area,conducting a comprehensive analysis of quartz samples from different stages of the deposit.This analysis includes SEM-CL observation,microtemperature measurement of fluid inclusions,laser Raman spectroscopy,and H-O isotopic compositional analysis.Through examination of the relationship between the veins and the symbiotic combination between the minerals,four distinct mineralization stages have been identified.The mineralization stages at the study site are prioritized as follows:(1)quartz-scheelite stage,(2)quartz-pyrite stage,(3)quartz-pyrite-arsenopyrite-polymetallic sulfide stage,and(4)quartz-calcite stage,and the main mineralization stages are the second and third stages.Fluid inclusions within the quartz at each stage were categorized into three types,namely aqueous inclusions(TypeⅠ),aqueous and CO_(2)three-phase inclusions(TypeⅡ),and pure CO_(2)inclusions(TypeⅢ).The homogeneous temperatures of the four phases of fluid inclusions range from 264℃to 347℃,255℃to 329℃,194℃to 271℃,and 157℃to 235℃respectively,aand the salinities range from 2.82%to 8.56%NaCl_(eqv),from 1.84%to 9.04%NaCleqv,from 2.24%to 11.23%NaCl_(eqv),and from 1.87%to 8.71%NaCl_(eqv).The H-O isotope analysis indicates that the ore-forming fluids in the Jiangdong gold deposit are predominantly sourced from magmatic fluids,likely associated with magmatic activities during the Yanshanian period.Fluid-rock interactions may have resulted in the early ore-forming fluids being influenced by partially metamorphic fluids.Over the course of mineralization from early to late stages,the composition of the ore-forming fluid transitioned from a mediumtemperature and medium-low salinity H_(2)O-NaCl-CO_(2)system to a medium-low temperature and medium-low salinity H_(2)O-NaCl system.Gol

关 键 词：流体包裹体 H⁃O同位素 成矿流体 江东金矿床 万古金矿田 湘东北 

分 类 号：P618.51[天文地球—矿床学]