鄂尔多斯盆地西南部下白垩统铀成矿关键控矿因素与找矿方向OA
Key Ore-controlling Factors and Exploration Directions of Uranium Mineralization in Lower Cretaceous of Southwestern Ordos Basin
近年来,在鄂尔多斯盆地西南部发现了新庄大型砂岩铀矿产地,赋矿主要层位为下白垩统环河组和洛河组,厘定其关键控矿因素对下一步扩大找矿工作具有重要意义.文章通过路线地质调查、钻孔岩心编录、地球化学测试、电子显微镜观察和鉴定、图件编制等手段,开展了铀成矿关键控矿因素研究,指出铀成矿受下白垩统基底古隆起及隆起带上发育的北西—南东向断裂、辫状河三角洲平原相砂体、氧化-还原蚀变带和环河组与洛河组之间的层序界面联合控制.天环向斜西翼斜坡带上发育的下白垩统基底古隆起带,既控制着赋矿层沉积体系类型和砂体规模,又控制着深部油气排泄,是区域铀成矿最关键的控矿因素;隆起带上发育的北西—南东向断裂构造,为深部渗出还原流体上升运移提供通道并形成铀成矿过程中必要的还原障,也是渗入含氧富铀流体的排泄区;铀矿化集中分布于辫状河三角洲平原北西西—南东东向主河道及两侧的相变过渡部位、灰色砂体占比在20%～60%区间及环河组和洛河组之间的层序界面,岩性-岩相-氧化还原界面控矿明显.基于铀成矿关键控矿要素的分析与厘定,提出镇原(开边—新庄—三岔镇)—环县地区、北石窟寺地区、盐池地区为下一步重点找矿有利地区.
In recent years,Xinzhuang large-scale sandstone-type uranium deposit has been discovered in southwestern Ordos Basin.The main ore-hosting horizons are Huanhe Formation and Luohe Formation of Lower Cretaceous.Therefore,the clarification of the key ore-controlling factors is of great significance for the next step of expanding prospecting work.This study analyzed key ore-controlling factors by traverse geological surveys,drilling core logging,geochemical testing,electron microscope observation and identification,map compilation,etc..It was found that uranium mineralization is jointly controlled by the paleo-uplift of Lower Cretaceous basement and NE-SW trending faults developed on the uplift zone,sandstone bodies of braided river delta plain,oxidation-reduction alteration zones,and the sequence boundary between Huanhe Formation and Luohe Formation.The paleo-uplift zone of the Lower Cretaceous basement developed on the slope zone of the western limb of Tianhuan syncline controled both the sedimentary system type and sandstone body size of the mineralization horizon and the deep oil and gas expulsion,making it the most critical ore-controlling factor for regional uranium mineralization.NE-SW trending fault structures developed on the uplift zone provided channels for the ascending migration of deep exudative reducing fluids and form necessary reducing barriers during the uranium mineralization process.They were also the discharge areas for infiltrating oxygen-rich uranium-bearing fluids.Uranium mineralization is concentrated in NWW-SEE trending main channel of the braided river delta plain and the phase transition zones on both sides,with the percentage of gray sandstone bodies ranging from 20%to 60%,as well as the sequence boundary between Huanhe Formation and Luohe Formation,indicating significant lithology-lithofacies-redox interface ore control.Based on the analysis and determination of the key ore-controlling factors of uranium mineralization,Zhenyuan(Kaibian-Xinzhuang-Sancha Town)-Huanxian area,Beishikusi area,and Yanchi area were proposed as the key favorable areas for the next step prospecting.
武正乾;贺峰;冯博;刘持恒;毛宁
核工业二〇三研究所,陕西 西安 710086铀资源探采与核遥感全国重点实验室,北京 100029||核工业北京地质研究院,北京 100029核工业二〇三研究所,陕西 西安 710086铀资源探采与核遥感全国重点实验室,北京 100029||核工业北京地质研究院,北京 100029核工业二〇三研究所,陕西 西安 710086
天文与地球科学
控矿因素找矿方向砂岩型铀矿鄂尔多斯盆地西南部
ore-controlling factorsexploration directionssandstone-type uranium depositsouthwestern Ordos Basin
《铀矿地质》 2026 (1)
31-46,16
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)资助.
评论