Proterozoic to Mesozoic East Gondwana: The juxtaposition of India, Sri Lanka, and Antarctica

Abstract

Jurassic and Cambro‐Ordovician paleomagnetic pole positions deduced from rocks of Sri Lanka and Antarctica generally conform when Sri Lanka is juxtaposed with the coast of Lützow‐Holm Bay, East Antarctica, in a manner similar to a current Gondwana reassembly. The Highland and Southwest groups (mostly Proterozoic) of Sri Lanka are correlated with the Ongul and Skallen groups of East Antarctica on the basis of similar lithology, structural characteristics, structural trend, tectonothermal history (ranging from early Proterozoic to Mesozoic), and the pressure‐temperature‐time path of the main metamorphism. Some neighboring lithotectonic units are also comparable between the two areas. Fracture‐lineament systems of Sri Lanka and Antarctica formed after the latest Silurian and during or before the Jurassic conform in this reconstruction. An improved fit of the 2000 m isobaths of India‐Sri Lanka‐Antarctica and continuation of the latest Archaean mobile belt from Enderby Land to peninsular India is obtained by fitting Sri Lanka into Lützow‐Holm Bay, and Enderby Land into the embayment in the east coast of peninsular India. This juxtaposition of peninsular India to East Antarctica involves about 80 km northward movement and about 30° clock‐wise rotation of Sri Lanka relative to India. The reassembly thus obtained accords well with data, supporting the idea that East Gondwana existed from the earliest Proterozoic to middle Mesozoic, although some disruption‐collision events of limited scale are considered possible. Copyright 1992 by the American Geophysical Union.