黔东铜仁地区磷块岩型铀矿床岩石地球化学特征  

Geochemical Characteristics of Phosphorite-type Uranium Deposits in Tongren Area,Eastern Guizhou

作　　者：王琼 徐进鸿 吴林锋 吴承泉[3] 彭松 李溪遥 靳子茹 范云飞 卢平 WANG Qiong;XU Jinhong;WU Linfeng;WU Chengquan;PENG Song;LI Xiyao;JIN Ziru;FAN Yunfei;LU Ping(Geological Survey Institute for Nuclear Resources,Non-Ferrous Metals and Nuclear Industry Geological Exploration Bureau of Guizhou,Guiyang,Guizhou 550005,China;School of Economics and Management,Tongren University,Tongren,Guizhou 554300,China;State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang,Guizhou 550081,China;University of Chinese Academy of Sciences,Sciences,Beijing 100049,China)

机构地区：[1]贵州省有色金属和核工业地质勘查局核资源地质调查院,贵州贵阳550005 [2]铜仁学院经济管理学院,贵州铜仁554300 [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,贵州贵阳550081 [4]中国科学院大学,北京100049

出　　处：《铀矿地质》2022年第6期1137-1151,共15页Uranium Geology

基　　金：铜仁学院博士科研启动基金项目(编号:trxyDH2106);国家自然科学基金项目(编号:U1603245);贵州省地质勘查基金项目(编号:MCHC-ZG20212206-2)联合资助。

摘　　要：黔东铜仁地区广泛发育早寒武世黑色岩系,已发现多个中小型含铀磷块岩型矿床,为探究其成因,文章选取矿化现象较好的大坳、牛角冲、溪门口和新冲等地出露的老堡组-牛蹄塘组剖面开展系统采样,进行岩石地球化学特征研究。分析结果显示老堡组硅质岩、磷块岩和牛蹄塘组碳质页岩具有介于陆源物质和海底热液之间的Fe_(2)O_(3)/TiO_(2)、Al_(2)O_(3)/(Al_(2)O_(3)+Fe_(2)O_(3)+MnO)、Zr/Hf、Y/Ho值,以及相对平坦的稀土元素配分模式,揭示铜仁地区磷块岩型铀矿形成于受陆源物质输入影响的正常海相沉积环境,部分受到海底热液影响;硅质岩、磷块岩和碳质页岩具有高δU值(>1)、低Th/U值(<2)、高V/(V+Ni)值(>0.6)和明显的Ce负异常,进一步表明这些含铀磷块岩型形成于贫氧-缺氧的还原环境。综合分析认为由于Rodinia超大陆裂解,受大陆风化和海底热液共同作用,在还原条件下形成了具有正常海水沉积和海底热液作用混合成因的含铀磷块岩。Tongren area in eastern Guizhou is characterized by widely distributed Early Cambrian black rock series,and well endowed with numerous small and medium-sized deposits of uranium-bearing phosphorite.In order to explore the genesis of these deposits,this paper chose the rich deposit in Da’ao,Niujiaochong,Ximenkou and Xinchong strata sections and made systematic sampling from Laobao-Niutitang Formation to carried out geochemical study.The analysis results showed that the siliceous rocks and the phosphorites of Laobao Formation,and the carbonaceous shale of the Niutitang Formation bear the Fe_(2)O_(3)/TiO_(2)、Al_(2)O_(3)/(Al_(2)O_(3)+Fe_(2)O_(3)+MnO)、Zr/Hf、Y/Ho values between terrigenous materials and seafloor hydrothermal fluids,and relatively flat distribution pattern of REE,revealing that the phosphorite-type uranium deposits in Tongren area were formed in a normal marine sedimentary environment influenced by the input of terrigenous materials,and partly influenced by seafloor hydrothermal fluids.The siliceous rocks,phosphorites and carbonaceous shale have highδU value(>1),low Th/U value(<2),high V/(V+Ni)value(>0.6)and obvious negative Ce anomaly,further indicating that these uranium-rich phosphorite rock were formed under an oxygen-poor-hypoxic reducing environment.Comprehensive analysis showed that the uranium-rich phosphorite was formed under normal seawater deposition mixed by seafloor hydrothermal action under reducing conditions due to the disintegration of the Rodinia supercontinent and continental weathering.

关 键 词：铀矿床 磷块岩 老堡组 铜仁 

分 类 号：P595[天文地球—地球化学] P619.14[天文地球—地质学]