Geochemical characteristics of epigenetic alteration and its constraints on mineralization in lower segment of Zhiluo Formation, Shuanglong area, southern Ordos Basin

Abstract

Green-color sandstone illustrates close association to the deposition of sandstone-type uranium via field exploration, which is similar to the Dongsheng area. Geochemical research on acidolysis hydrocarbon, Th/U, Fe3+/Fe2+ and organic carbon content in Zhiluo Formation were conducted, aiming to decipher the uranium mineralization in the green color sandstone.The result shows that: (1) Primary gray sandstone hold the higher content of hydrocarbon than the green altered and oxidized ones, and then the green altered sandstone.(2)Both oxidized sandstone and green alteration sandstone were chartererised by high Th/U (0.37-1.82) and low organic content (0.01%-1.24%).Green alteration was probably triggered by intensive reduced material, that is, the secondary reduction of reducing fluid.The early interlayer oxidation provided the material basis for uranium mineralization, and the later secondary reduction preserved the integrity of the ore body.This study has an important indication for the discrimination and division of interlayer oxidation zone in this area, and provides an important basis for the study of metallogenic regularity of sandstone type uranium deposits.

Keywords

• shuanglong area
• zhiluo formation
• sandstone-type uranium deposit
• geochemistry