松辽盆地南部余粮堡地区砂岩型铀矿含矿层碎屑岩地球化学特征及物源分析  

Geochemical Characteristics and Provenance Analysis of Clastic Rocks for Sandstone-type Uranium Deposit in Yuliangbao Area,Southern Songliao Basin

作　　者：严张磊 郭强 肖菁[1,2,3] YAN Zhanglei;GUO Qiang;XIAO Jing(National Key Laboratory of Uranium Resource Exploration-Mining and Nuclear Remote Sensing,Beijing 100029,China;Beijing Research Institute of Uranium Geology,Beijing 100029,China;CNNC Key Laboratory of Uranium Resource Exploration and Evaluation Techniques,Beijing 100029,China)

机构地区：[1]铀资源探采与核遥感全国重点实验室,北京100029 [2]核工业北京地质研究院,北京100029 [3]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》2024年第5期864-880,共17页Uranium Geology

基　　金：中核集团青年英才项目“大型陆相沉积盆地找矿目标层砂体精准预测”(编号:地QNYC2022)资助。

摘　　要：随着砂岩型铀矿勘查工作的不断深入,在松辽盆地南部余粮堡地区虽已发现多处铀矿化,但至今找矿工作尚未取得突破性进展。而对于可地浸砂岩型铀矿找矿和评价而言,明确赋铀砂体的物源是关键。文章对区内典型钻孔的矿化段进行系统取样,通过对其主、微量元素的测试结果分析,借助相关地球化学特征指数对研究区物源进行剖析:岩石化学蚀变指数(CIA)为46.38~69.69,平均值为57.08,指示研究区碎屑岩处于弱风化作用,干旱古气候条件,元素组成变化不大,较好地保留了源区的地球化学性质;La-Th-Sc、Th-Co-Zr/10、Th-Sc-Zr/10及(Fe_(2)O_(3)总+MgO)-Al2O3/SiO_(2)等图解以及稀土元素特征均指示物源区的构造背景以大陆岛弧为主,兼有大陆边缘的性质;通过与上地壳特征参数对比,Th/Sc-Zr/Sc、La/Th-Hf、ΣREE与La/Yb等散点图以及δEu的异常可以证明物源区成分以上地壳的长英质岩石为主,结合盆地南部物源供给体系进一步分析,认为盆地西缘和南缘发育的中-新生代火山岩和海西期、燕山期的花岗岩是主要的物质来源。With the more exploration for sandstone-type uranium deposits in Yuliangbao area,southern Songliao Basin,uranium mineralization has been found in several sector,but no breakthrough has been made in the deposit prospecting so far.Therefore,the provenance identification of uranium hosing sand bodies become important for the prospecting and evaluation of in-situ leachable sandstone uranium deposits.In this paper,the mineralized section of typical boreholes in the area was systematically sampled,and the test results of main and trace elements were analyzed.The provenance properties of the study area were analyzed by means of the relevant geochemical characteristic index system.The rock chemical alteration index(CIA)was found ranging from 46.38 to 69.69,with an average value of 57.08,indicating that the clastic rocks in the study area were under weak weathering,arid paleoclimate conditions,and little change in element composition,which better preserved the geochemical properties of the source area.The diagrams of La-Th-Sc,Th-Co-Zr/10,Th-Sc-Zr/10 and(Fe_(2)O_(3)+MgO)-Al2O3/SiO_(2)as well as the characteristics of rare earth elements indicated that the tectonic background of the source area was dominated by continental island arc with the nature of continental margin.The scatterplot of Th/Sc-Zr/Sc,La/Th-Hf,ΣREE and La/Yb,as well as theδEu anomaly,proved that the composition of the provenance region was mainly feldspathic rocks in the upper crust.Further analysis of the provenance supply system in the southern basin suggested that Mesozoic and Cenozoic volcanic rocks and Hercynian and Yanshanian granites developed in the western and southern margins of the basin were the main material sources.

关 键 词：松辽盆地 砂岩型铀矿 物源 地球化学 风化作用 构造背景 

分 类 号：P619.14[天文地球—矿床学]