GEOCHEMISTRY AND SEDIMENT PROVENANCE OF SANDSTONE FROM YAOJIA FORMATION IN CENTRAL DEPRESSION, SOUTHERN SONGLIAO BASIN

The sediment provenance is of indicative significance to study the distribution of uranium sand body and migration channel of uranium fluid. Taking the Yaojia Formation in Central Depression of southern Songliao Basin as object, based on the systematic geochemical testing of sandstone samples and collected data of neighboring Qianjiadian uranium deposit, the paper discusses the geochemistry, formation environment and sediment provenance of sandstone of Yaojia Formation and compares with those in Qianjiadian area. The results show that the sandstone detrital of Yaojia Formation is relatively rich in Si and Al, with the main rock types of lithic sandstone and arkose. The REE content is 160.12×10^-6-253.74×10^-6, characterized by enriched LREEs (La, Ce, Pr, etc.), flat HREEs (Ho, Er, Tm, Yb and Lu) and moderate negative Eu anomaly. The analysis of major, trace and rare earth elements reveal that the sandstone was formed in arid-semiarid climate, without high degree of chemical alteration, and the tectonic setting of provenance is active continental margin. Combined with the regional tectonic background, it is considered that the provenance component of the study area is similar to that of Qianjiadian area, but the source directions are different. The parent material for sandstone detrital of Yaojia Formation in the study area is derived from the northeast or southwest provenance, with the main source rocks of granodiorite and granite.