巴音戈壁盆地塔木素铀矿床紫红色铀矿石矿化特征  

Mineralization characteristics of the purplish red uranium ore in the Tamusu uranium deposit within the Bayan Gobi basin

作　　者：刘旭 夏菲[1] 张成勇[1] 张群喜[1] 刘波[2] 侯树仁[2] LIU Xu;XIA Fei;ZHANG Cheng-yong;ZHANG Qun-xi;LIU Bo;HOU Shu-ren(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;Geological Party No.208,China National Nuclear Corporation,Baotou 014010,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208大队,内蒙古包头014010

出　　处：《矿物学报》2023年第3期325-336,共12页Acta Mineralogica Sinica

基　　金：国家自然科学基金项目(编号:42062008,42172098);中国铀业与东华理工大学核资源与环境国家重点实验室联合创新基金项目(编号:NRE2021-15);东华理工大学研究生创新专项资金(编号:DHYC-202213)。

摘　　要：巴音戈壁盆地塔木素铀矿床是我国北方特大型砂岩型铀矿床,但矿化特征特殊,具有品位高、矿层多等特征,其矿床成因一直存在争议,亟需新的证据来破解铀矿化成因机制。项目组野外地质调查中,发现产于氧化带内的紫红色铀矿石,具有明显的热液改造的痕迹,是一种新类型的铀矿化。笔者通过岩矿鉴定、蚀刻径迹、电子探针等实验,系统分析了该地区紫红色铀矿石的矿物蚀变特征,并探讨了铀的富集成因。研究认为,塔木素紫红色铀矿石与热液蚀变关系密切,其蚀变带可划分为萤石脉带,紫红色含萤石胶结物带和灰白色高岭石化带;铀矿物主要呈分散吸附状与胶磷矿范围分布一致。该类型铀矿石是深部还原性富U、P热流体上移进入含矿目的层与氧化带弱碱性流体相互作用的产物,pH、Eh条件的改变造成U、P同时沉淀和富集。结合矿体地质特征分析,认为塔木素矿床为表生氧化流体和深部热流体相互作用下形成的具复合成因砂岩型铀矿床,表生氧化流体造成蚀源区和地层中的铀迁移并在氧化还原过渡界面富集沉淀,而热流体携带了深部铀源进入氧化带内形成富磷型铀矿石,这是造成塔木素矿床铀品位高且矿体多层的主要原因。The Tamusu uranium deposit in the Bayan Gobi Basin is a super-large sandstone-type uranium deposit in northern China.However,it has special mineralization characteristics,with high grade and many ore layers.Its genesis has been controversial.New evidences are urgently needed to solve its mechanism of uranium mineralization.In the field geological survey of the project team,it was found that the purplish red uranium ore occurred in the oxidation zone had obvious reworking traces of hydrothermal fluid.This is a new type of uranium mineralization.Through rock and mineral identification,etching track,electron probe and other experiments,we have systematically analyzed mineral alteration characteristics of the purple uranium ore in this area,and discussed the genesis of uranium enrichment of the deposit.It is believed that the purple-red uranium ore of the Tamusu deposit is closely related to the hydrothermal alteration,and its alteration zone can be classified into fluorite vein subzone,purple-red fluorite cement subzone and grayish white kaolinite subzone.Uranium minerals occurred mainly in dispersed and adsorbed states whose distribution is consistent with that of collophane.This type of uranium ore is the product of the interaction between the deep reductive U-and P-rich hydrothermal fluid moved into the ore-targeting layer and the weak alkaline fluid in the oxidation zone.The change of pH and Eh conditions caused the simultaneous precipitation and enrichment of U and P.Combined with the analysis of geological characteristics of the ore body,it is considered that the Tamusu deposit is a sandstone-type uranium deposit with composite genesis formed by the interaction of supergene oxidation fluid and deep hydrothermal fluid.The supergene oxidation fluid caused the migration of uranium from the erosion source area and the stratum,and the enrichment and precipitation of uranium at the redox transition interface,while the hydrothermal fluid which carried the deep sourced uranium into the oxidation zone had formed the ph

关 键 词：砂岩型铀矿 铀磷矿化 热流体活动 层间氧化作用 塔木素 

分 类 号：P611[天文地球—矿床学] P614[天文地球—地质学]