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Authors
Affiliations
1 Geological Survey of India, 29, J. L. Nehru Road, Calcutta 700016, IN
2 Department of Geology, The University of Western Australia, Nedlands WA 6009, AU
3 School of Physics and Geosciences, Curtin University of Technology, Bentley WA 6102, AU
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 35, No 5 (1990), Pagination: 480-496
Abstract
Preliminary Pb-Pb and Rb-Sr geochronology of granitic and gneissic rocks from the Sukma area of the Bastar craton, Central India, provides important constraints on crustal evolution, Much of the craton is made up of felsic orthogneisses and younger granitic intrusives, compositionally ranging from tonalite to granite. Pb-Pb isotopic data suggest the presence of ca. 3.0 Ga old gneisses. Younger granitic intrusives have been dated at ca. 2.6 Ga which represents a widespread resetting and/or emplacement event. Comparison of the Pb-Pb and Rb-Sr whole rock ages suggests that the latter were more perturbed after the gneiss-forming or emplacement events. All rock suites show significant geological scatter of isotopic data probably because of sampling on a regional scale, and reflect multi-stage isotopic evolution in a complex terrain.
The present isotopic data indicate the presence of Archaean rocks in the Bastar craton and suggest temporal similarity with the oldest crustal rocks in the Singhbhum and Dharwar cratons.
Keywords
Bastar Craton, Geochemistry, Geochronology, Isotope Geology, Madhya Pradesh.
