Evolution of Proterozoic Aravalli Delhi Fold Belt in the northwestern Indian Shield from seismic studies

A deep seismic reflection study across the Aravalli Delhi Fold Belt, situat ed in the northwestern part of the Indian Shield, has revealed a deep penet rating 25-km-wide crustal-scale thrust fault, dipping reflections from the upper crust to the Moho and a divergent reflection fabric. Paleo-subduction zones and island-are signatures are identified from the present study. Sei smic images of the crust reveal tectonics of the region with two distinct e pisodes of rifting, sedimentation, collision and suturing corresponding to the Aravalli and Delhi orogenies. Plate tectonic processes were responsible for the evolution of the Paleoproterozoic Aravalli and Mesoproterozoic Del hi Fold Belts with the juxtaposition of the Bundelkhand craton in the east and the Marwar craton in the west. A 50-Omega m electrical conductor, exten ding to a depth of 25 km, and a steep gradient gravity anomaly of 70 mGal, extending all along the strike of the fold belt with conspicuous lows on ei ther side, correlate well with the deep-seated dipping reflections/sutures inferred from the seismic reflection data. The present study suggests that a high-velocity, thick crust was produced in the Proterozoic orogens of the region. (C) 2000 Elsevier Science B.V. All rights reserved.