苗儿山中段向阳坪铀矿床绿泥石特征及其成岩成矿意义  

Characteristics of chlorite in Xiangyangping uranium ore deposit, middle segment of Miaoershan and its petrogenetic and metallogenic significance

作　　者：谭双[1,2,3] 陈琪 万建军[1] 高翔 吴昆明[2,3] 欧阳平宁[2,3] 张涛 TAN Shuang;CHEN Qi;WAN Jian-jun;GAO Xiang;WU Kun-ming;OUYANG Ping-ning;ZHANG Tao(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;Changsha Uranium Geology Research Institute,CNNC,Changsha 410007,China;Hunan Engineering and Technology Research Center for Evaluation and Comprehensive Utilization of Associated Radioactive Mineral Resources,Changsha 410007,China)

机构地区：[1]东华理工大学核资源与环境国家重点实验室,江西南昌330013 [2]核工业二三〇研究所,湖南长沙410007 [3]湖南省伴生放射性矿产资源评价与综合利用工程技术研究中心,湖南长沙410007

出　　处：《岩石矿物学杂志》2022年第6期1097-1108,共12页Acta Petrologica et Mineralogica

基　　金：中核集团青年英才项目(CNNC2021-230);“十四五”国防预先研究项目;中国核工业地质局地勘项目(202222);核资源与环境国家重点实验室开放基金(2020NRE04);放射性地质与勘探技术国防重点学科实验室开放基金项目(2022RGET05)。

摘　　要：向阳坪铀矿床是近年在苗儿山地区发现的重要矿床,绿泥石化是向阳坪铀矿床重要的蚀变类型和找矿标志。本文对向阳坪矿床发现的铀-绿泥石型矿石的蚀变矿物学特征进行了系统地观察,结合电子探针原位微区分析,查明了绿泥石相关矿物的共生组合关系,获得了其化学定量分析结果,划分了绿泥石的种类及其形成条件,在此基础上探讨了绿泥石性质及其对铀成矿的启示。结果显示,向阳坪铀矿床绿泥石可分为黑云母蚀变型、裂隙充填型、铀矿物相关型和黏土矿物吸附铁镁质转变型4种。铁硅协变图解表明向阳坪矿床主体为铁镁绿泥石,部分为蠕绿泥石,含少量的密绿泥石。据经验公式计算所得绿泥石形成温度变化范围为190~265℃,平均239℃,属中低温热液蚀变,其形成机制包括溶蚀-结晶和溶蚀-迁移-结晶2种。绿泥石化为铀成矿过程提供了所需的环境,促进了铀的活化、迁移并最终沉淀成矿。The Xiangyangping uranium ore deposit is a new-found deposit in Miaoershan ore field for the past few years. Chloritization is one of the most important alteration types and prospecting indicators in the Xiangyangping uranium deposit. Based on the detailed field and interior petrographic observation for the ore samples in the Xiang-yangping uranium deposit, electron probe microanalyzer(EPMA) is employed to study paragenetic association characteristics and morphological features of chlorites. Chemical compositions of chlorites could help to confirm the chemical types of chlorites and formation condition of chlorites, and finally to discuss their formation mechanism and the relationship with uranium mineralization. The chlorites in the Xiangyangping uranium ore deposit could be divided into four types, including biotite-alteration type, fracture-filling type, uranium-associated types and clay minerals transformed types. The Fe-Si diagram has revealed that the chlorites are mainly brunsvigite area, partly ripidolite and few pycnochlorite, respectively. The formation temperature range of chlorite is 190~265℃( averagely239℃), which belong to the mesothermal epithermal alteration. The formation mechanism is dissolution-crystallization and dissolution-migration-crystallization. The chloritization provided the environment for uranium mineralization, and promoted the activation, migration and deposition of uranium.

关 键 词：绿泥石 电子探针 形成温度 铀成矿 向阳坪铀矿床 

分 类 号：P578[天文地球—矿物学] P616[天文地球—地质学]