Geochemical characterization of basement granite and their implication on uranium mineralization in Eastern margin of Chhattisgarh Basin, Bargarh District, Western Odisha

The Precambrian Sambalpur granitoid batholith (2380 Ma) occupying a major part in the western Odisha form the basement for younger supracrustal cover sequence of Meso- to Neoproterozoic age. The batholith consists of different varieties of granites and gneisses. Significant uranium mineralisation has been located along the unconformable contact between basement granitoid and Chhattisgarh Supergroup, and is hosted by the granite and the basal unit of Singhora and Chandrapur Groups. The granite hosted mineralisation is primarily controlled by fractures (NE-SW to NNE-SSW), sympathetic to regional structural grain of Eastern Ghat Mobile Belt (EGMB) and occur close to eastern margin of the basin. Uranium ore minerals are uraninite, pitchblende, coffinite, kasolite and uranophane. The basement granites are two mica bearing and analysed high silica and potash contents. These granitoid belong to granodiorite - adamellite - granite suite and exhibit metaluminous to peraluminous, differentiated nature and their development of volcanic arc tectonic setup. High U/Th ratio suggesting the labile nature of uranium and its enrichment over Th. Hence, these granites and overlying Chhattisgarh sediments hold potential for unconformity proximal / fracture controlled uranium mineralisation. (author)