四川盆地北部砂岩型铀矿岩石学特征及矿床成因研究OA北大核心CSTPCD

[Objective]Uranium resources are China's important strategic resources and energy minerals.The thorough understanding of geological characteristics and metallogenic models of sandstone-type uranium deposits in the northern Sichuan Basin is to the benefit of exploration and development.[Methods]The petrological characteristics of sandstone-type uranium deposits are studied through field investigation,rock and mineral identification and geochemical analysis,and the mineralization process is analyzed.[Results]The ore-bearing rocks are mainly the calcareous cementation medium-fine-grained sandstone and conglomerate of the Lower Cretaceous Cangxi Formation.Uranium exists in the form of authigenic uranium minerals.Uranium minerals are mainly coffinite,which are in xenomorphic,euhedral and hypautomorphic granular.[Conclusions]The metamorphic acidic volcanic rocks and granites of the Tiechuanshan Formation in Micangshan provided the initial uranium source for the formation of sandstone-type uranium deposits in the basin.Uranium migrates in the form of carbonic acid containing uranyl ions in the aqueous solution.The reductive environment of swamps and stagnant water rich in organic matter and pyrite destroys the carbonic acid containing uranyl ions,causing uranium to precipitate and accumulate in the primary diagenesis stage and secondary epigenesis stage.