塔里木盆地巴什布拉克铀矿床黑色泥岩成因及其对铀成矿的指示  

The Genesis of Black Mudstone in Bashibulake Uranium Deposit in Tarim Basin and Its Indication for Uranium Mineralization

作　　者：张成勇[1] 张明正[2] 夏菲[1] 刘旭 邓薇[3] 傅钰坤 李海啸 石贝贝 黎海东 ZHANG Chengyong;ZHANG Mingzheng;XIA Fei;LIU Xu;DENG Wei;FU Yukun;LI Haixiao;SHI Beibei;LI Haidong(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang,Jiangxi 330013,China;Geologic Party No.216,CNNC,Urumqi,Xinjiang 830011,China;Jiangxi Engineering Laboratory on Radioactive Geoscience and Big Data Technology,East China University of Technology,Nanchang,Jiangxi 330013,China)

机构地区：[1]东华理工大学地球科学学院,江西南昌330013 [2]核工业二一六大队,新疆乌鲁木齐830011 [3]东华理工大学江西省放射性地学大数据技术工程实验室,江西南昌330013

出　　处：《铀矿地质》2024年第5期823-836,共14页Uranium Geology

基　　金：国家自然科学基金项目(编号:42062008、42272097);东华理工大学江西省放射性地学大数据技术工程实验室开放基金项目(编号:JELRGBDT202104)联合资助。

摘　　要：巴什布拉克矿床是塔里木盆地重要的铀矿床,具有蚀变类型多样、矿石品位高、矿体呈多层板状等特点。铀矿化的分布与地沥青关系紧密,但地沥青的形成时间及其与铀成矿的关系仍不清楚,影响了矿床成因的认识和勘查方向的选择。文章选择以灰黑色泥岩和泥砾为研究对象,通过野外观察、岩石矿物学和X荧光光谱仪测量等,查明黑色泥岩的特征,厘定地沥青的发育时间及其与铀成矿的关系。结果表明,黑色泥岩产于砂砾岩层内部,呈薄夹层状产出,主要由泥晶白云石、半自形黄铁矿和大量团块状地沥青组成;铀矿物以铀石-细晶黄铁矿和UO_(2)/TiO_(2)混合物-地沥青矿物组合赋存在黑色泥岩矿石中,且U与Pb、Zn、Cu等同步富集。地沥青为下部油气逸散运移至近浅表地层中氧化分解的产物,形成于克孜勒苏群沉积-早成岩阶段,其形成与早白垩世的末期(115~113 Ma)塔西南地区岩浆活动造成的区域热事件有关。克孜勒苏群沉积-早成岩阶段的富U烃类流体是形成该矿床的关键因素,富U烃类还原性盆地流体与盆浅层地层水的流体混合作用导致U和Pb、Zn、Cu、Se等矿质的大规模沉淀,也为后期地表的氧化改造提供基础。Bashibrak deposit is an important uranium deposit in Tarim Basin,which is characterized by diverse alteration types,high ore grade,and multi-layer tabular orebody.The distribution of uranium mineralization is closely related to the asphalt,but the age of asphalt and its relationship to uranium mineralization are still unclear,which restricts the interpretation of ore genesis and the next exploration direction.In this paper,gray black mudstone and gravel were selected as the research objects to determine the formation time of asphalt and its relationship with uranium mineralization,through field observation,rock mineralogy,and X-ray fluorescence spectroscopy measurements.The results show that black mudstone occurs in a thin layer inside the gravel layer,mainly composed of mud crystal dolomite,semi self shaped pyrite,and a large amount of block land-bitumen.Uranium minerals occur in black mudstone ores as a combination of coffinite,fine-grained pyrite and UO_(2)/TiO_(2)mixture-asphalt minerals,and U is enriched synchronously with Pb,Zn,Cu,etc.The asphalt is the result of the oxidation and decomposition of the lower oil and gas migrated to the near shallow strata,formed during the early sedimentary diagenesis stage of the Kizilsu Group.Its formation is related to regional thermal events caused by magmatic activity in the southwestern region of Tarim during the late Early Cretaceous period(115~113 Ma).The key to the formation of this deposit is the rich U hydrocarbon fluid deposited in the early diagenetic stage.The mixing of the reductant basin fluid of the rich U hydrocarbon with the shallow formation water of the basin resulted in the large-scale precipitation of minerals such as U and Pb,Zn,Cu,Se,etc.,which also provided a foundation for the later surface oxidation transformation.

关 键 词：黑色泥岩 地沥青 铀矿物学 克孜勒苏群 巴什布拉克 

分 类 号：P619.14[天文地球—矿床学]