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Granite-migmatite; Grenvillian event; zircon population; remnant charnockite

Spectacular exposures of granulite-migmatite occur in the Chilka Lake area of the Eastern Ghats belt. The garnetiferous granite gneiss of peraluminous granitic composition, often contains restitic metapelite inclusions and is demonstrably a product of biotite-dehydration melting in pelitic rocks. On the other hand, older layers and bands of charnockitic rocks frequently occur as dismembered patches within the peraluminous granite, thus imparting a measled appearance of the granite exposures.

The partial melting and emplacement of the peraluminous granite represent the Grenvillian thermal event, as evidenced by Rb-Sr whole rock and Pb-Pb zircon dating. On the other hand, minor patches of charnockite represent migmatized relict, as evidenced by some older zircons, in addition to those of Grenvillian age.

S Bhattacharya¹ M P Deomurari² W Teixeira³

1. Indian Statistical Institute, 203 B.T. Road, Calcutta - 700 035, India
2. Physical Research Laboratory, Ahmedabad, India
3. Institute of Geosciences, Sao Paulo University, Brazil

Published

December 2002

Manuscript received

2 April 2002

Manuscript revised

30 July 2002