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

Abstract

A deep seismic reflection study across the Aravalli Delhi Fold Belt, situated in the northwestern part of the Indian Shield, has revealed a deep penetrating 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-arc signatures are identified from the present study. Seismic images of the crust reveal tectonics of the region with two distinct episodes 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 Delhi Fold Belts with the juxtaposition of the Bundelkhand craton in the east and the Marwar craton in the west. A 50-Ωm electrical conductor, extending to a depth of 25km, and a steep gradient gravity anomaly of 70mGal, extending all along the strike of the fold belt with conspicuous lows on either 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.