Uranium metallogenic model of the Lower Cretaceous in the northern Ordos Basin

Abstract

Since 2019, major breakthroughs have been made in the prospecting of the Lower Cretaceous sandstone-type uranium deposits in the northern Ordos Basin. The Lower Cretaceous sandstone layer is expected to become another important sandstone-type uranium prospecting target after the Middle Jurassic. Establishing the metallogenic model of the Lower Cretaceous provides a better guide for prospecting work. Based on previous regional geological, drilling cores, and analytical data, the authors systematically summarized the basic geological characteristics of uranium mineralization in the Lower Cretaceous in this area and preliminarily established the uranium metallogenic model of the Lower Cretaceous.The results suggest the six Lower Cretaceous rock types can be divided into three geochemical types. Uranium mineralization mainly occurs in the brown-gray sandstone, which is the transition zone from brown-red sandstone to green sandstone. The green sandstone is formed by oxidation first and then reduction.The metallogenic type is dominated by interlayer oxidation, supplemented by phreatic oxidation in the Late Cretaceous. The Lower Cretaceous "secondary oxidation" uranium metallogenic model can be divided into three stages: first oxidation mineralization stage, large-scale reduction mineralization stage, and second oxidation mineralization stage.These research results can provide a new idea for uranium exploration in new strata of Ordos Basin.

Keywords

• metallogenic model
• sandstone-type uranium deposit
• lower cretaceous
• northern ordos basin