Tracing the Proterozoic continental collision in NW India: a geophysical approach


K. Naganjaneyulu, Electrical and Electromagnetic Lab, National Geophysical Research Institute, Council of Scientific and Industrial Research (CSIR), Hyderabad 500007, India. E-mail:


The 800 km-long Aravalli–Delhi Fold Belt (ADFB) in the Aravalli Mountains of Rajasthan defines the largest tectonic feature in the northwestern (NW) Indian shield, situated between the late Proterozoic Marwar Basin in the west and the Vindhyan Basin in the east. The final collision between the Aravalli and Delhi domains defining ocean closure and continental amalgamation is critical in understanding the culmination of the Proterozoic Wilson Cycle in NW India. We present for the first time a regional three-dimensional (3-D) gravity model to evaluate the architecture of the continental collision signature of this region. The deep seismic reflection data along a 400 km-long profile across the ADFB highlights two sets of reflection bands with opposite dips. The prominent west-dipping reflections observed in the central domain, towards the western margin of the Mangalwar Complex could be related to the Palaeoproterozoic subduction of an oceanic lithosphere, and suggest a clear northwestward subduction polarity. The data showing gravity highs, the high elevation features, and the models proposed in the present study, together with the presence of high-density bodies in the deep crust, is interpreted as a signature of magmatic underplating and/or mafic-ultramafic intrusives. The high elevations and corresponding high-density anomalies at depth can also be explained by domal uplift, following the extrusion of metamorphic orogens into the mid crust, as well as the presence of eclogitized material at depth associated with the subduction–collision tectonics and continental amalgamation. Copyright © 2011 John Wiley & Sons, Ltd.