东胜砂岩型铀矿氧化酸性流体与还原碱性热液流体过渡界面蚀变带成矿作用研究  

Alteration and Metallogeny on the Oxic-Acid/Anoxic-Alkali Interface of the Dongsheng Uranium Deposit in Northern Ordos Basin

作　　者：李荣西[1,2] 段立志[1,2] 陈宝赟[1,2] 张少妮[1,2] 

机构地区：[1]长安大学西部矿产资源与工程地质教育部重点实验室,陕西西安710054 [2]长安大学国土资源部成矿作用及其动力学开放研究实验室,陕西西安710054

出　　处：《大地构造与成矿学》2011年第4期525-532,共8页Geotectonica et Metallogenia

基　　金：国家重点基础研究发展计划项目(编号:2003CB2146000)资助

摘　　要：位于鄂尔多斯盆地北部地区的东胜砂岩型铀矿在平面上和垂向上具有明显的岩石学和地球化学分带性,矿物学和岩相学特征研究表明其分带性是不同性质流体蚀变作用造成的。根据氧化/还原过渡界面蚀变矿物特征及其相互交代关系,识别出早、晚两个世代蚀变矿物组合,分别反映出早期蚀变流体为氧化环境下的酸性流体,晚期蚀变流体为还原环境下的碱性热液流体。早期氧化环境的酸性流体蚀变作用基础上叠加了晚期还原环境下的碱性热液流体蚀变作用,导致了铀在氧化/还原过渡界面的富集成矿。分析认为,东胜铀矿热液蚀变与鄂尔多斯盆地乃至华北地区燕山期构造活动和岩浆活动产生的区域性热异常事件具有一定联系。The Dongsheng uranium deposit,located at northern Ordos Basin in north-central China,is the largest sandstone type uranium deposit discovered in recent years in China.The uranium deposit developed in braided fluvial sandstone of middle Jurassic Zhiluo Formation.The Dongsheng uranium deposit has the basic characteristics of sandstone-type uranium of interlayer oxic zone but also displays the basic characteristics of hydrothermal alteration.Petrology and geochemistry studies indicate that the uranium deposit has obvious geochemical and mineralized alteration zones both horizontally and vertically.The sandstone in oxic zone is characterized by mottled color and oxide minerals such as carbonate,sericite,illite,kaolinite and limonite.The sandstone in anoxic zone is characterized by gray coarse sandstone with low temperature hydrothermal altered minerals like albite,carbonate,chlorite,pyrite and epidote.Uranium ores mainly developed in sandstone along the oxic/anoxic interface.The uranium minerals are mainly coffinite with minor brannerite and uraninite.Homogenization temperature of fluid inclusions in cements of uranium sandstone is 150~160 ℃.It indicates that hydrothermal alteration of the Dongsheng uranium deposit and even in north Ordos Basin was related to the Mesozoic regional magmatic events in Northern China.

关 键 词：氧化/还原过渡界面 热液蚀变作用 成矿流体 东胜铀矿 鄂尔多斯盆地 

分 类 号：P611[天文地球—矿床学] P619.14[天文地球—地质学]