地质通报2026，Vol.45Issue(5)：795-817,23.DOI:10.12097/gbc.2025.04.060
二连盆地乌兰察布坳陷中部上白垩统赛汉组层间氧化带地球化学特征、形成机理及其找矿潜力分析
Geochemical characteristics,formation mechanism,and exploration potential analysis of the interlayer oxidation zone of the Upper Cretaceous Saihan Formation in the central Ulanqab Depression of the Erlian Basin
摘要
Abstract
[Objective]The characteristics of interlayer oxidation zone restrict sandstone-type uranium mineralization.Therefore,it is of great significance to study the geochemical characteristics and genesis of interlayer oxidation zone for evaluating the potential of sandstone-type uranium mineralization.[Methods]According to the drilling information,combined with sand dispersion system mapping,sediment debris composition,environmental sensitive parameters and elemental geochemical characteristics,the key information of interlayer oxidation zone was analyzed.[Results]The research reveals that the sand bodies in the study area are mainly composed of red sandstone,yellow sandstone,grey ore-bearing sandstone and primary grey sandstone,which correspond to the strongly oxidized zone,weakly oxidized zone,transitional zone and reducing zone,respectively.The average values of environmentally sensitive parameters including Th/U,TOC,Fe2+/Fe3+,S2-and total sulfur content are as follows:2.56,0.1%,0.35,4.62×10-6 and 0.03%for the strongly oxidized zone;1.89,0.1%,0.15,5.68×10-6 and 0.03%for the weakly oxidized zone;1.05,0.17%,0.42,6.03×10-6 and 0.04%for the transitional zone;1.02,0.2%,0.72,16.49×10-6 and 0.09%for the reducing zone;and 0.03,0.58%,0.93,29.22×10-6 and 0.41%for the ore-bearing zone.Trace elements including Y,Co,Ni,Zn,Sm,Gd,Dy and Er exhibit the highest average contents in the ore-bearing zone,with the respective values of 21.67×10-6,32.72×10-6,20.84×10-6,47.63×10-6,3.95×10-6,3.11×10-6,3.12×10-6 and 1.81×10-6.[Conclusions]The results indicate that all environmentally sensitive parameters show a gradually increasing trend from the strongly oxidized zone to the ore-bearing zone.Elements including Y,Co,Ni,Zn,Sm,Gd,Dy and Er are enriched in the mineralization areas of the transitional zone.When the oxygen-containing uranium-containing fluid enters the uranium reservoir,the oxygen in the fluid reacts with the reducing substances in the sand body,Fe2+is oxidized to Fe3+,U(Ⅳ)is oxidized to U(Ⅵ),and migrates with the fluid in the form of uranyl complex ions.When the oxygen in the fluid is gradually depleted,Fe3+is reduced to Fe2+and combined with S2-to form pyrite.Uranyl complex ions are reduced to form pitchblende and precipitated,and some U(Ⅳ)reacts with SiO42-to form uraninite.When the mineralization occurs,the complexation degree of different complex anions in the fluid with trace elements and rare earth elements is different,which makes the four trace elements such as Y,Co,Ni and Zn and the four rare earth elements such as Sm,Gd,Dy and Er enriched at the same time.Uranium mineralization is mainly developed in the transition zone near the weak oxidation zone,indicating that the transition zone and near the oxidation zone is a favorable uranium prospecting area in the study area.关键词
二连盆地/乌兰察布坳陷/上白垩统/层间氧化带/地球化学/铀矿Key words
Erlian Basin/Ulanqab Depression/Upper Cretaceous/interlayer oxidation zones/geochemistry/uranium deposit分类
天文与地球科学引用本文复制引用
刘阳,罗宁,余小林,臧永亮,李名,俞礽安,陈璐璐..二连盆地乌兰察布坳陷中部上白垩统赛汉组层间氧化带地球化学特征、形成机理及其找矿潜力分析[J].地质通报,2026,45(5):795-817,23.基金项目
中国地质调查局项目《二连盆地红格尔等铀矿调查区钻探、测井》(编号:DD20240116-3)、中国石油华北油田分公司项目《二连盆地脑木更北次洼精准评价及周边有利区带部署研究》(编号:HBYT-EL-2022-JS-179)、《2024 年脑木更等凹陷 BSK1 地质调查钻孔》(编号:HBYT-ZBZX-FWTP-2024-0598)和中陕核工业集团有限公司《油铀兼探勘查技术系统集成及三维地质编录数字化应用研究项目》(编号:61250101) Supported by China Geological Survey Project(No.DD20240116-3),China Petroleum North China Oilfield Branch Projects(Nos.HBYT-EL-2022-JS-179,HBYT-ZBZX-FWTP-2024-0598)and ZSH Industry Group Co.LTD.Project(No.61250101) （编号:DD20240116-3）
