A Pan-African thermal event in southern India

UPb zircon data from five igneous suites confirm previous studies that demonstrated widespread Pan-African magmatism in the Granulite Terrain of southern India. Ages determined here are ∼560 Ma for the Peralimala Granite and ∼555 Ma for the Kalpatta Granite, both north of the Palghat-Cauvery lineament, and ∼585 Ma for a charnockite in the Cardamom massif south of the lineament. Zircon from a pegmatite in the Kerala khondalite belt at Melankode yields an age of 512 Ma. Resetting of zircons in the 2500-Ma Arsikere Granite of the western Dharwar craton probably occurred at ∼450 Ma. These ages and the concentration of Pan-African granitic magmatism around the Indian portion of a broad region of granulite-facies metamorphism in East Gondwana demostrates generation of a restricted area of high temperature either above a rising plume or a zone of rifting. Mantle-derived fluids continued to move upward through the crust of southern India for at least 100 m.y. after the peak of magmatism, and the entire region was still cooling at 400 Ma.