A Mesoproterozoic Supercontinent: Evidence from the Indian Shield

Abstract

Geophysical signatures of late Paleoproterozoic collisional sutures/fold belts between the Deccan Protocontinent and Bundelkhand craton, and between the Bundelkhand and Mewar cratons of the north Indian shield are presented. The Aravalli and Satpura orogenies evolved during these continent-continent collision episodes. Both the orogenic episodes are associated with granulite facies metamorphism and metallogeny. Serpentinised ultramafic breccia in ophiolitic melange is present in both regions. Structural discontinuities and oppositely dipping reflection fabrics with high conductivity anomalies are the characteristic features of these collision zones. A major gravity high is also observed all along the strike of these fold belts to a distance of 700-1000 km. Paleoproterozoic (1.8-2.1 Ma) ages corresponding to compressional activity have also been observed in the Southern Granulite Terrain and other Gondwana fragments. Extensive granites and gneisses of ∼1900 Ma age are observed in the lower Himalayas and Nanga Parbat ranges. Late Paleoproterozoic orogenic activity is also observed in all of the earth's shields. Intense orogenic activity of this period observed in various widely separated cratonic blocks is related to global plate tectonic processes and supercontinental episodes. The available geophysical evidences in various parts of the globe suggest the presence of a supercontinent, referred to as ‘Columbia’ during the early Mesoproterozoic period.