Multiple convergences along an Archean craton margin: Clues from Proterozoic ophiolite remnants, granites and granulite domains along the SE margin of India

Abstract

A collage of disparate tectonostratigraphic units intermittently stitched together in the Paleoproterozoic to Neoproterozoic constitutes the southeastern margin of the Archean Eastern Dharwar Craton (EDC). Two small ophiolitic slivers namely the 1.9 Ga Kandra Ophiolite Complex and the 1.33 Ga Kanigiri Ophiolitic Mélange (KOM) indicate two separate subduction-related intra-oceanic arcs outboard of the EDC margin in the Paleoproterozoic and the Mesoproterozoic, respectively. Post-tectonic granites intrusive into the KOM, adjoining domains of the Nellore Schist Belt and the Nallamalai Fold Belt add to the bulk of the collage which also includes the Ongole domain of the southern Eastern Ghats Belt. Generation of UHT granulite and migmatitic granite during 1.68-1.54 Ga probably indicating collision related tectonothermal activity, relate the Ongole domain to the Rayner complex of East Antarctica, which have similar isotopic signatures. The tectonic collage was welded with the EDC margin only in the Neoproterozoic as the intracratonic to cratonic marginal basins namely the Cuddapah Basin and the Kurnool Basin had open sea connections from the Paleoproterozoic to the Neoproterozoic. We re-examine the geological, structural and geochronological data in order to understand the applicability of a plate tectonic paradigm toward the growth of the EDC margin in the Proterozoic, and possible global connections.