New discovery in the study of remote sensing image characteristics in sandstone-type uranium districts in China and its significance

Sandstone-type uranium deposits are now one of the main targets for uranium prospecting in China. Prospecting commonly emphasizes lithology, stratigraphy, lithofacies, and ore-controlling factors, while the influence of faulting is usually neglected. Systematic research of features from remote sensing images of sandstone-type uranium deposits shows fault-controlled commercial mineralization occurs in most major sandstone-type uranium ore districts. This paper discusses characteristics of faults and their roles in controlling mineralisation, particularly faults penetrating the basin and basement rocks. Based on the above research, a new ore-controlling model-“structure-geochemical barrier model” is put forward. It is pointed out that the “structure-geochemical barrier model” is a metallogenic model that differs from the traditional interlayer oxidation zone model. The new metallogenetic model proposes that gases, water and oil migrate upward along faults as a result of fault mobilization and form a geochemical variation zone where uranium is precipitated. These are distinct from uranium-bearing and oxygen-bearing water migrating along ore-hosting horizons from oxidizing to reducing environments, with uranium precipitated in redox transition zone. This is an important model for non-typical geosyncline platform environments. It is of significance for uranium reconnaissance and prospecting in China. Attention should be paid not only to lithology and lithofacies research but also to the roles of ore-controlling faults.