鄂尔多斯盆地西南缘中下侏罗统地层物源及构造演化对铀成矿的制约  

Provenance and Tectonic Evolution of the Middle and Lower Jurassic Strata Constraints on the Uranium Mineralization in Southwest Margin of Ordos Basin

作　　者：俞礽安 李彤 杨桐旭 赵华雷 涂家润 胡永兴[4] 唐永香[5] Yu Reng’an;Li Tong;Yang Tongxu;Zhao Hualei;Tu Jiarun;Hu Yongxing;Tang Yongxiang(Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China;Tianjin Center of Geological Survey,China Geological Survey,Tianjin 300170,China;Key Laboratory of Uranium Geology,China Geological Survey,Tianjin 300170,China;Geological Survey Institute of Gansu Province,Lanzhou 730000,China;Tianjin Geothermal Exploration Institute,Tianjin 300250,China)

机构地区：[1]中国地质科学院矿产资源研究所,北京100037 [2]中国地质调查局天津地质调查中心,天津300170 [3]中国地质调查局铀矿地质重点实验室,天津300170 [4]甘肃省地质调查院,甘肃兰州730000 [5]天津地热勘查开发设计院,天津300250

出　　处：《地球科学》2024年第5期1793-1809,共17页Earth Science

基　　金：国家自然科学基金委重点支持项目(No.92162212);中国地质调查局地质调查项目(No.DD20221678-05)。

摘　　要：鄂尔多斯盆地西南缘位于阿拉善地块、秦岭造山带与祁连造山带3个构造单元的交汇部位,给含铀岩系地层的物源体系和铀成矿作用研究带来一定困难.通过选取泾川研究区的直罗组和延安组砂岩进行碎屑锆石U-Pb测年和微量元素研究,分析结果显示:泾川地区直罗组砂岩的碎屑锆石年龄呈215~767Ma和1501~1905Ma;延安组砂岩的碎屑锆石年龄呈215~453Ma、1506~1918Ma和2136~2579Ma.与源区同位素年代学对比认为直罗组和延安组砂岩的物源成分较为复杂,主要来自于阿拉善地块,其次来自于华北板块北缘和北祁连地区.从延安组到直罗组沉积期,祁连山和阿拉善陆块发生了快速隆升和剥蚀,为直罗组提供了物源,并且古生代和中生代侵入岩体提供物源的占比逐渐增大.研究西部靠近盆缘地区以中侏罗统砂岩层为找矿目的层,靠近盆内含矿层位逐渐变年轻.The southwest margin of the Ordos basin is located at the intersection of the Alxa massif,the Qinling orogenic belt and the Qilian orogenic belt,which is challenging to the study of the provenance and uranium mineralization of the uranium bearing rock.This paper selects the Zhiluo Formation and Yan’an Formation sandstones in the Jingchuan area to conduct clastic zircon U-Pb dating and trace element research.The analysis results show that the clastic zircon ages of the Zhiluo Formation sandstones in Jingchuan area are 215-767 Ma and 1501-1905 Ma;The clastic zircon ages of Yan’an Formation sandstones are 215-453 Ma,1506-1918 Ma and 2136-2579 Ma,respectively.Compared with the isotopic chronology of the source area,it is believed that the provenance components of the Zhiluo and Yan’an Formation sandstones are relatively complex,mainly from the Alxa block,followed by the northern margin of the North China plate and the North Qilian area.During the sedimentary period from Yan’an Formation to Zhiluo Formation,Qilian Mountain and Alxa landmass were rapidly uplifted and denuded,providing provenance for Zhiluo Formation,and the proportion of provenance provided by Paleozoic and Mesozoic intrusive rocks gradually increased.The study shows that the strata of middle Jurassic can be taken as the prospecting target strata in the west margin of basin,and the ore bearing strata near the basin gradually become younger.

关 键 词：鄂尔多斯盆地 泾川 中下侏罗统 碎屑锆石U-PB年龄 物源 矿床 构造地质 

分 类 号：P611[天文地球—矿床学]