Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

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2.9 b.y. Rb-Sr Age of the Granulite Facies Rocks of Satnur-Halagur and Sivasamudram Areas, Karnataka, South India


Affiliations
1 Department of Geology, Bangalore University, Bangalore-560056, India
2 Centre Armoricain d'Etudes Structurales des Socles, CNRS, Laboratoire de geochronologie et geochimie isotopique, 35042 Rennes, France
     

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Preliminary Rh-Sr isotopic studies of the granulites occurring SW of Kabbaldurga were undertaken to verify the possibility of an earlier granulite facies event. The Rb-Sr data obtained gives an imperfect isochron age of 2950 ± 234 m.y. with an initial ratio of 0.7032 ± 22 (MSWD = 52). The age obtained may correspond to subconcomitant protolith-metamorphism age or metamorphism alone. The high error may be due to non-cogenetic nature of the rocks analysed or a small disturbance of the Rb-Sr system during the 2500 m.y. high-grade event. The present study indicates probability of the occurrence of an early granulite facies event prior to 2500 m.y.
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  • 2.9 b.y. Rb-Sr Age of the Granulite Facies Rocks of Satnur-Halagur and Sivasamudram Areas, Karnataka, South India

Abstract Views: 237  |  PDF Views: 2

Authors

B. Mahabaleswar
Department of Geology, Bangalore University, Bangalore-560056, India
J. J. Peucat
Centre Armoricain d'Etudes Structurales des Socles, CNRS, Laboratoire de geochronologie et geochimie isotopique, 35042 Rennes, France

Abstract


Preliminary Rh-Sr isotopic studies of the granulites occurring SW of Kabbaldurga were undertaken to verify the possibility of an earlier granulite facies event. The Rb-Sr data obtained gives an imperfect isochron age of 2950 ± 234 m.y. with an initial ratio of 0.7032 ± 22 (MSWD = 52). The age obtained may correspond to subconcomitant protolith-metamorphism age or metamorphism alone. The high error may be due to non-cogenetic nature of the rocks analysed or a small disturbance of the Rb-Sr system during the 2500 m.y. high-grade event. The present study indicates probability of the occurrence of an early granulite facies event prior to 2500 m.y.