Rb-Sr Geochronology and Petrochemistry of the Granitoids Hosting Rare Element Pegmatites, Jharsuguda District, Orissa

Whole-Rock isochron dating of granite gneiss, hosting rare element-Bearing pegmatites from Jharsuguda district, Orissa defines an isochron age of 2762±±200Ma with initial ⁸⁷Sr/⁸⁶Sr ratio of 0.7082 ± 0.0027 (MSWD = 36.8). High ⁸⁷Sr/⁸⁶Sr ratio indicates involvement of crustal source for its formation. Petrography of the granitoids characterizes them as 'hornblende granite gneiss'. The ASI of the granite gneiss reveals its meta-Aluminous nature. It is a significant host to the zoned and complex type of 'Rare Elements-Bearing Pegmatites' , containing columbite-Tantalite (oxide of Nb + Ta) and beryl. Based on the whole-Rock isochron data, the granite gneiss of the Jharsuguda area can be equated with the Bamra and Tamparkola granite and phase III of the Singhbhum granite. Further, it postdates the Bonai and Kaptipada granite but is older to the Nilgiri and Ramapahari granite, with all these forming part of the Singhbhum North Orissa Craton.