贵州三穗龙湾大型铀矿床铀的赋存状态和地球化学研究  

A study on the occurrence status of uranium and geochemistry of the large-scale Longwan uranium deposit in Sansui County,Guizhou Province

作　　者：黄启琳 吴承泉[1,2] 徐进鸿 王琼 李溪遥 彭松 范云飞 卢平 靳子茹 HUANG QiLin;WU Chengquan;XU Jinhong;WANG Qiong;LI Xiyao;PENG Song;FAN Yunfei;LU Ping;JIN Ziru(State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang Guizhou 550081,China;University of Chinese Academy of Sciences,Beijing 100049,China;Tongren University,School of Economics and Management,Tongren Guizhou 554300,China;Non-Ferrous Metals and Nuclear Industry Geological Exploration Bureau of Guizhou,Nuclear Resources Geological Survey Institute,Guiyang Guizhou 550005,China)

机构地区：[1]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 [2]中国科学院大学,北京100049 [3]铜仁学院经济管理学院,贵州铜仁554300 [4]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

出　　处：《矿物学报》2024年第4期508-525,共18页Acta Mineralogica Sinica

基　　金：国家自然科学基金项目(编号:2018U1812402);国家重点研发计划项目(编号:2022YFC2903403);贵州省教育厅高等学校科学研究项目青年项目(编号:黔教技[2022]349号);贵州省地质勘查基金项目(编号:MCHC-ZG20212206-2)。

摘　　要：贵州三穗县龙湾铀矿床是近年勘查发现的大型铀矿床,矿体呈层状、似层状产于震旦-寒武系老堡组黑色岩系中。前人对该矿床开展了矿床地质和地球化学研究,但铀的赋存状态、成矿物质来源和成矿环境尚不明确。本文选取龙湾矿床南部的老棚剖面为研究对象,开展矿物学和全岩元素地球化学研究。研究结果表明铀主要以沥青铀矿和钛铀矿等的独立铀矿物形式存在于磷灰石矿物边缘、裂隙及孔洞处,部分以类质同象形式赋存于磷灰石的晶格中。全岩地球化学分析结果显示样品Y/Ho值为16.3~63.2(均值为40.3),Zr/Hf值为33.6~79.3(均值为42.3),靠近上地壳的值;样品具有相对平坦的稀土元素配分模式,显示无-弱Eu正异常(δEu为0.27~1.19,均值为0.82);硅质岩Ge/Si值为1.23×10^(-6)~0.15×10^(-6)(均值为0.47×10^(-6)),均接近现代海水平均值,表明龙湾铀矿床成岩成矿物质来源主要为陆源风化碎屑物质,受到海底热水作用的影响小。样品V/(V+Ni)值为0.43~0.98(均值为0.80),Ni/Co值为1.80~58.0(均值为12.7),具有明显Ce负异常(δCe值为0.31~0.81,均值为0.60),表明龙湾铀矿床形成于还原沉积环境中。综合研究表明,在新元古代晚期-晚古生代早期,黔东地区大陆风化作用为海洋提供了铀,在还原条件下形成龙湾黑色岩系型铀矿床。The Longwan uranium deposit in Sansui County,Guizhou Province,is a large-scale uranium deposit discovered by exploration in recent years.Its orebodies occurred in layered and quasi-layered forms in the black rock series of the Sinian-Cambrian Laobao Formation.Previous studies on the geology and geochemistry of the deposit were conducted.However,the occurrence status of uranium,the source of ore-forming materials,and the metallogenic environment of the deposit are still unclear.In this study,the Laopeng profile located in the southern part of the Longwan deposit has been selected as the research object for studying its mineralogy and whole-rock elemental geochemistry.The results reveal that uranium occurred mainly in the form of independent uranium minerals such as pitchblende and brannerite in edges,fissures and holes of apatite grains,or partly in the form of isomorphism in the crystal lattice of apatite.The results of whole-rock geochemical analyses reveal that samples from the Laobao Formation have Y/Ho values ranging from 16.3 to 63.2(with an average of 40.3),Zr/Hf values ranging from 33.6 to 79.3(with an average of 42.3),which are similar to those of the upper crust.These samples have relatively flat REE distribution patterns,with no or weak Eu positive anomalies(δEu values ranging from 0.27 to 1.19,at an average of 0.82).The siliceous rocks have Ge/Si values ranging from 1.23×10^(-6) to 0.15×10^(-6)(with an average of 0.47×10^(-6)),which are similar to those of the modern seawater,suggesting that the lithogenous and ore-forming materials of the Longwan deposit were mainly sourced from the continental weathering clastic materials which were limitedly affected by the seafloor hydrothermal fluid.The samples from the Laobao Formation have V/(V+Ni)values ranging from 0.43 to 0.98(with an average of 0.80),and Ni/Co values ranging from 1.80 to 58.0(with an average of 12.7),with significantly negative Ce anomalies(δCe values ranging from 0.31 to 0.81,at an average of 0.60)on their REE distribution patterns,sug

关 键 词：黑色岩系型铀矿床 赋存状态 地球化学 矿床成因 贵州三穗 

分 类 号：P61[天文地球—矿床学] P595[天文地球—地质学]