鄂尔多斯盆地南部镇原地区环河组下段赋矿砂岩基本特征与铀成矿作用  

Basic Feature of Mineralization Host Rocks and Its Relation to Uranium Metallogenesis in Zhenyuan,Southern Ordos Basin

作　　者：武正乾 胡永兴[2] 刘坤鹏 王晓鹏 刘持恒 王凯 张良 毛宁 王奇辉 WU Zhengqian;HU Yongxing;LIU Kunpeng;WANG Xiaopeng;LIU Chiheng;WANG Kai;ZHANG Liang;MAO Ning;WANG Qihui(Research Institute No.203,CNNC,Xi'an,Shaanxi 710086,China;Geology survey of Gansu province,Lanzhou,Gansu 730000,China;CNNC Key Laboratory of Uranium Resources Exploration and Evaluation Technology,Beijing Research Institute of Uranium Geology,Beijing 100029,China)

机构地区：[1]核工业二〇三研究所,陕西西安710086 [2]甘肃省地质调查院,甘肃兰州730000 [3]核工业北京地质研究院中核集团铀资源勘查与评价技术重点实验室,北京100029

出　　处：《铀矿地质》2023年第6期960-969,共10页Uranium Geology

基　　金：中国核工业地勘基金项目“鄂尔多斯盆地南部旬邑-盐池地区铀矿资源评价与勘查”(编号:2022-17);中核集团集中研发项目“砂岩型铀矿多重耦合地质成矿作用与时空定位(编号:中核科发2021-143)”联合资助。

摘　　要：文章通过分析鄂尔多斯盆地南部镇原地区赋矿砂岩下白垩统环河组下段的沉积学、岩石学、地球化学等基本特征,分析了赋矿砂岩与铀矿形成的关系,旨在促进该地区找矿工作。通过地表调查、钻孔岩心观察、电子显微镜对赋矿砂岩进行观察和鉴定,环河组下段是该区主要的含矿层位,发育冲积扇-辫状河-辫状河三角洲相-湖泊相沉积体系,主要发育棕红色、浅黄色、灰色中细砂岩和灰绿色中砂岩,填隙物主要为碳酸盐和少量高岭石和绿泥石等黏土矿物,见有少量褐铁矿、黄铁矿等;灰色岩系具有较好的还原能力,有利于铀矿的还原成矿。环河组下段NWW—SEE向氧化—还原过渡带控制铀矿化分布,与NE—SW向断裂关系密切。晚白垩世以来,伴随盆地西缘及周缘岩石中的铀顺层向盆地中心发生层间渗入作用,深部油气藏的大规模排烃沿断裂上涌发生油气渗出作用,富氧含铀流体中的铀离子与油气中的还原剂发生强烈的氧化还原作用,导致铀沉淀成矿。Based on the analysis of the sedimentology,petrology and geochemistry of the lower Cretaceous Huanhe formation of the mineralization host sandstone in Zhenyuan area,southern Ordos basin,the relationship between the host sandstone and the formation of uranium metalogenis was analyzed with the aim of promoting the exploration in the region.Through ground investigation,drilling core observation and electron microscope observation and identification of ore-hosting sandstone,the lower member of Huanhe formation was regarded as the main ore-hosting horizon in this area,which developed alluvial fan-braided,river-braided river delta,facies-lacustrine facies sedimentary system,and maily consist of brownish-red,light-yellow,and grayish medium-small grain sandstone and grayish-green medium grain sandstone.,gray-green medium-fine sandstone.The filler of rocks is mainly carbonate and a small amount of kaolinite,chlorite and other clay minerals,limonite,pyrite,etc.;The gray rock system has a better reducing ability,which is conducive to the reduction of uranium ore formation.The NWW—SEE Extending oxidation-reduction transition zone in the lower member of the Huanhe Formation controls the distribution of uranium mineralization,and is closely related to the NE—SW striking fracture.Since the Late Cretaceous,uranium of source rocks around the western margin of the basin infiltrated into the host rocks downward the dirp of the strata,the large-scale hydrocarbon expulsed from the deep oil and gas reservoirs upwell along the fault and occurs oil and gas seepage at the surface,and uranium in the down-drip oxygen-rich fluids was acted precipitated by the strong redox action with the oil and gas,leading to uranium enrichment and mineralization.

关 键 词：赋矿砂岩 环河组下段 砂岩型铀矿 成矿关系 鄂尔多斯盆地 

分 类 号：P619.14[天文地球—矿床学]