Potential for Unconformity-Related Uranium Deposits in the Northern Part of the Cuddapah Basin, Telangana and Andhra Pradesh, India

The intra-cratonic, Mesoproterozoic Cuddapah Basin in the Dharwar Craton hosts several types of uranium deposit in various stratigraphic levels. Uranium mineralization is recorded in the lower part of the Gulcheru and Vempalle Formations and along the unconformity between the granitic basement and the overlying sediments of the Srisailam/Banganapalle Formation in the upper part of the Cuddapah sequence. The Srisailam and Palnad sub-basins, located in the northern part of the Cuddapah Basin, host Proterozoic unconformity-related uranium mineralization. Mineralization in these sub-basins occurs close to the unconformity between the basement complex containing granitoids, basic dykes of Palaeoproterozoic age, greenstone belts of Archaean age and arenaceous, argillaceous and calcareous sediments of Mesoproterozoic-Neoproterozoic age. Sub-surface exploration over two decades has established the presence of three small to medium tonnage uranium deposits at Lambapur (~1200 tU), Peddagattu (~6400 tU) and Chitrial (~8000 tU) which are located along the unconformity between the basement Mahabubnagar granite and the overlying Srisailam Formation in the Srisailam sub-basin; and one small deposit at Koppunuru (~2300 tU) close to the unconformity contact between basement granite and the Banganapalle Formation of the Kurnool Group in the Palnad sub-basin. In all these deposits, uranium mineralization is concealed and lies below the cover rocks at a depth of <5-150 m. Uranium mineralization located in these sub-basins show dissimilarities with those unconformity-type uranium deposits known in Australia and Canada, especially in respect of their geometry, basement composition and the absence of palaeosol (regolith).