Tummalapalle Group Uranium Deposits, Cuddapah Basin: Their Significance for Proterozoic Glaciation and Supercontinent Cycle in the Eastern Dharwar Craton, India - A Review

ABSTRACT The Vempalle Formation of Papaghni sub-basin in the southwestern margin of Cuddapah Basin (CB) hosts low-grade, large tonnage uranium deposits collectively called ‘Tummalapalle Group Uranium Deposits’ and has been recognised as a major uranium province in India. These uranium deposits are hosted by uraniferous phosphatic siliceous dolostone (UPSD). UPSD has several enigmatic characters, such as regional dolomicrite blanketing, laminated structure, signatures of gas seep structures, negative δ13C values (~0 to −2.9‰), contrasting primary sedimentary structures indicating shallow and deep marine conditions, contrasting marine and continental sediments like alternate carbonate-rich and phosphate-rich layers mixed with quartz and felspar clasts. Geochemically, it has higher SiO2 (22.62%), Al2O3 (2.64 %), FeO (0.74%), and P2O5 (0.75%) with lesser CaO (22.58%) than common dolostones. Interestingly, UPSD sediments are unusually enriched in redox-sensitive elements like Mo, Cu and V. Signatures of the Supercontinent cycle are observed across the Archaean-Proterozoic boundary in the Papaghni sub-basin at the base of the Cuddapah basin, in the Eastern Dharwar Craton. Glaciation is inferred to be associated with the Supercontinent cycle. UPSD is identified as a Cap Carbonate Rock (CCR), deposited during glacial melting. Methane released during the glacial melting appears to have reduced uranium derived from the surrounding provenance. This new perspective is proposed for the uranium mineralisation.