湘西沃溪金锑钨矿床白钨矿、黑钨矿与磷灰石U-Pb定年及其地质意义  

U-Pb dating of scheelite,wolframite and apatite from the Woxi Au-Sb-W deposit,western Hunan Province and their geological significance

作　　者：祝亚男 彭建堂[3] 邢朗彰[3] 唐燕文 ZHU YaNan;PENG JianTang;XING LangZhang;TANG YanWen(College of Resources and Environmental Engineering,Guizhou University,Guiyang 550025,China;MOE Key Laboratory of Karst Geological Resources and Environment,Guizhou University,Guiyang 550025,China;State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China)

机构地区：[1]贵州大学资源与环境工程学院,贵阳550025 [2]贵州大学喀斯特地质资源与环境教育部重点实验室,贵阳550025 [3]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,贵阳550081

出　　处：《岩石学报》2023年第6期1829-1846,共18页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41702089、41972090);贵州省科技厅基础研究计划项目(黔科合基础1056)联合资助。

摘　　要：沃溪矿床位于湘西雪峰隆起区的转折部位,是该区金锑钨矿床的典型代表。该矿床成矿元素及成矿期次较为复杂,各成矿阶段的形成时代长期存在争议。本次研究在对沃溪矿床详细野外调查及岩相学观察的基础上,对深部中段矿体中的白钨矿、磷灰石及浅部中段矿体中的黑钨矿开展了U-Pb同位素分析。依据本次所获年龄数据,结合观察到的矿脉交切关系、矿物共生组合等特征,本文认为沃溪矿床除了加里东期成矿作用之外,还存在燕山期成矿作用。其中,白钨矿形成相对较早,成矿年龄为149.0±12Ma、144.8±1.7Ma、139.8±6.1Ma;黑钨矿与白钨矿同时生成(或稍晚),成矿年龄为137.8±3.9Ma、134.8±5.1Ma;自然金、辉锑矿主要在白钨矿、黑钨矿形成以后通过沉淀而成,且自然金在晚阶段(125.8±5.6Ma、123.8±4.6Ma)石英-碳酸盐脉中仍有少量产出。综合已有年代学资料推测,沃溪矿床可能在经历了加里东期陆内造山成矿作用之后,还经受了燕山期伸展构造背景下深部流体不同程度的叠加改造作用。而该矿床发现的矿脉原地破裂后被后期矿物胶结等现象,则指示其矿脉的形成与液压致裂作用有关,这种作用导致矿脉反复裂开-愈合,有利于成矿元素(尤其是金)的活化迁移和再富集沉淀。The Xuefeng Uplift in western Hunan is an important Au-Sb-W mineralization belt in South China,while the Woxi deposit is the largest gold deposit with a unique element association of Au-Sb-W in this region.As the ore-forming elements and mineralization stages of the deposit are relatively complex,there has been a long dispute about its mineralization ages.In this study,geological characteristics of scheelite,wolframite and pyrite(the most important gold-bearing mineral)and stibnite in the Woxi deposit were observed in details,and U-Pb dating of scheelite,wolframite and apatite were conducted with a LA-ICP-MS method.The results show that the Woxi deposit was genetically related to several hydrothermal events happened during the Late Jurassic to Early Cretaceous.Among the dated minerals,the scheelite is the earliest,which has the intercept ages of 149.0±12Ma,144.8±1.7Ma and 139.8±6.1Ma;and the wolframite was formed slightly later than the scheelite,with the intercept ages of 137.8±3.9Ma,134.8±5.1Ma.Native gold and stibnite were mainly precipitated after the formation of scheelite and wolframite,and there was still a small amount of native gold occurred in the late quartz carbonate vein(125.8±5.6Ma,123.8±4.6Ma).Combined with the published geochronological data,two periods of mineralization are revealed in the Woxi deposit,i.e.,the Caledonian intracontinental orogenesis and the Yanshanian extensional tectonic event,respectively.The fragments of earlier W-bearing quartz veins are usually in good collage and cemented by later Au-,Sb-bearing quartz veins,indicating that there was a succession of crack-seal processes which bring about hydraulic fracturing in the Woxi deposit.Such processes were conductive to the activation,migration,accumulation and precipitation of the ore-forming elements(especially gold)in the deposit.

关 键 词：白钨矿 黑钨矿 雪峰隆起区 沃溪 LA-ICP-MS U-Pb定年 

分 类 号：P618.2[天文地球—矿床学]