The influence of fluid mixing on the mineralization of sandstone type uranium deposits

The influence of different sources, compositions and properties of fluid mixing in different types of basins on the sandstone type uranium deposits was discussed in this paper. Fluid mixing changes physical and chemical conditions of the fluid and, what is more important, changes the chemical composition of the fluid, leading to the destruction of fluid chemical equilibrium and causing unloading mineralization of the fluid. In basins formed in different tectonic backgrounds, the impacts of fluid characteristics on the sandstone type uranium mineralization are different. In the uranium-oil-coal coexistent basin, the interaction between the uranium-bearing oxidizing fluid in the shallow layer and the organic reducing fluids associated with oil and gas plays an important controlling role in uranium mineralization, whereas in the basin under the tectonic environment, the mixing of orogenic belt fluid and basin deep source fluid exerts great influence on mineralization. However，in the rift basin under the extension environment, there often occur deep magmatic and hydrothermal fluid activities, and hence attention should be paid to the transformation and superposition enrichment role of the thermal fluid on sandstone type uranium deposits.