Abstract:

The in-situ leaching sandstonetype uranium deposit is one of the uranium deposits with important industrial values, and the main target of exploration in Chinese nuclear geologyWith the development of oil and natural gas exploration in the Ordos basin, a breakthrough in exploration of insitu leaching sandstonetype uranium deposit in the northern part of the basin has been achievedAfter a brief introduction to the metallogenic geological conditions of this type of uranium deposit in Ordos basin, we provide the temperature and salinity conditions as well as the isotopic geochemical parameters of the oreforming fluid, which are obtained by the comprehensive geochemical analysesThe hydrogen and oxygen isotopic analyses of fluid inclusions indicate that the fluid as the formation water was derived from the mixture of magmatic water and meteoric waterThe carbon and oxygen stable isotopic analyses of cements of Ubearing sandstones show that the genesis of carbonate cements was the mixtures of mantle carbon, organic carbon and sedimentary carbonThis information presents the evidence that the organic material did come into the oreforming process, which is of significance to the formation of insitu leaching sandstonetype uranium depositThe oreforming geochemical model for this type of uranium deposit has been establishedThe uranium oreforming processes include oxidizing and reducing processes, during which some elements are enriched and some are depleted, accompanied with the uranium migrationThis study is of significance for understanding the enrichment and sedimentation of uranium as well as for finding the similar types of uranium deposits in other related basins.

Key words:  sandstone-type uranium deposit; fluid inclusion; stable isotope; geochemistry; metallogenic models; the Ordos Basin