CHARACTERISTICS OF URANIUM MINERALIZATION OF THE SANDSTONE OF THE FIRST MEMBER, QUANTOU FORMATION, IN XIERSU DEPRESSION, SONGLIAO BASIN

The first member of Quantou Formation in Xiersu Depression, Songliao Basin, is divided into two parts. The lower part is dominated by alluvial fan facies; while the upper consists of alluvial fan-braided river facies. Analysis shows that the lower part is composed of mixed mud and gravels with coarse grains, which is adverse to mineralization. The upper part contains two layers of sandstone extending stably, with thickness ranging from 5 to 40 m, which is favorable for uranium mineralization. Because of the epigenetic reduction in deep organic fluid and the guidance of base-cap linked faults, the CBM in the lower layer moved upward, making the Quantou Formation changed to a reducing geochemical environment. By analysis of the contents of uranium and thorium and the characters of uranium mineralization, it is suggested that the amount of uranium is high in the sandstone of the first member of Quantou Formation in Daguanwujiazi and Talinbuduntu, with obvious activation and migration of uranium and epigenetic enrichment. The uranium exists mainly in adsorbent as clay minerals and organic matter. The main uranium mineral is pitchblende. It is concluded that the study area has a good potential for uranium mineralization.