甘肃龙首山铀成矿带青井地区钍矿化特征和成因研究OACSTPCD

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.