甘肃龙首山铀成矿带青井地区钍矿化特征和成因研究  

Characteristics and Genesis of Thorium Mineralization in Qingjing Area,Longshoushan Uranium Metallogenic Belt,Gansu

作　　者：王伟 耿海军 李涛 刘涛 戴鹏飞 WANG Wei;GENG Haijun;LI Tao;LIU Tao;DAI Pengfei(Research Institute No.203,CNNC,Xianyang,Shaanxi 712000,China)

机构地区：[1]核工业二〇三研究所,陕西咸阳712000

出　　处：《铀矿地质》2024年第4期680-694,共15页Uranium Geology

基　　金：中国核工业地质局铀矿勘查项目(编号:202220)资助。

摘　　要：钍资源是一种重要的潜在核能资源,对其开展调查研究具有重要的理论研究价值和勘查实践意义。近年来,核工业二〇三研究所在龙首山青井地区新发现了钍矿产地,矿体赋存于青井凹陷上侏罗统砾岩中,钍矿化明显受到F1断裂和辉绿岩脉的共同控制,矿化产于Ⅰ号和Ⅱ号辉绿岩脉夹持区内部的蚀变带内。蚀变和矿化砾岩呈灰白色、紫红色,成矿作用中大部分元素经历了活化、迁移和再富集的过程。矿石为紫红色砾岩,钍矿物主要为钍石,伴随钾长石化、赤铁矿化和碳酸盐化。结合钍石及围岩形成年龄,认为在晚侏罗世砾岩沉积期,本区沉积的大量碱性岩等砾石中具有较高钍含量,可能为本区钍矿化提供了初始钍源;在白垩纪之后,成矿热液沿F1断裂以及不同辉绿岩脉的夹持区运移,从砾岩中汲取大量成矿元素,使得含矿热液中Th含量进一步富集,然后在Ⅰ号和Ⅱ号辉绿岩脉夹持区富集沉淀,形成钍矿体。综上分析认为,青井地区钍矿化为形成于白垩纪之后的脉状热液型钍成矿作用。In recent years,a new thorium ore deposit was discovered in Qingjing area of Longshoushan metallogenic belt by the Research Institute No.203,CNNC.The ore body occurs in Upper Jurassic conglomerate in Qingjing Sag.The thorium mineralization is obviously controlled by F1 fault and diabase dikes.The thorium mineralization is obviously controlled by the F1 fault and the diabase dike,and the mineralization is strictly enclosed in the alteration zone between the No.I and No.II diabase dikes.The altered and mineralized conglomerates are flesh red and purplish red in color,and most elements in the mineralization have undergone the process of activation,migration and re-enrichment.The ore is purplish red conglomerate,and the thorium mineral is mainly thorite,accompanied by potassium feldspathization,hematite mineralization and carbonatization.Combined with the formation ages of thorium and wall rocks,it was considered that during the Jurassic conglomerate deposition period,a large number of alkaline rocks and other gravels deposited in this area with high thorium content,which may provide the initial thorium source for thorium mineralization in this area;after Cretaceous,the ore-forming hydrothermal fluid migrated along fault F1 and the pinches of diabase veins,and extracted a large number of ore-forming elements from the conglomerate,which further enriched the content of Th in the ore-bearing hydrothermal fluid,and then enriched and precipitated in the pinches of No.I and No.II diabase veins to form thorium ore bodies.Based on the above analysis,it was considered that the thorium mineralization in Qingjing area is a vein hydrothermal thorium mineralization formed after the Cretaceous.

关 键 词：钍矿 砾岩 钾交代 青井 龙首山 

分 类 号：P619.14[天文地球—矿床学]