A geotransect in the central Indian shield, across the Narmada-Son lineament and the central Indian suture

This paper reports on a geotransect in the central Indian shield along a 10 0 km wide NW-SE corridor between Hirapur and Rajnandgaon. This corridor has been selected based on two seismic profiles-a 235 km long seismic-refracti on/wide-angle-reflection profile between Hirapur and Mandla and a 130 km lo ng coincident deep-reflection/refraction profile between Seoni and Kalimati . Since the geologic, gravity, magnetic, and heat-flow data are available u p to Rajnandgaon, the second part of the corridor has been extended by anot her 80 km in the absence of seismic data. From northwest to southeast, the transect corridor covers different tectonic units of the Late Archean to Me soproterozoic Bundelkhand craton, the Paleoproterozoic to Mesoproterozoic S atpura mobile belt, the Middle Archean to Mesoproterozoic Kotri-Dongargarh mobile belt, and the Neoproterozoic Bastar craton. The seismic results in the Bundelkhand craton show lower crustal velocity v alues at a very shallow depth; these data have now been interpreted as a lo wer-crustal intrusive body that is present throughout the Bundelkhand crato n in the lower crust at depths of 23 to 25 km. Combined interpretation of s eismic travel times with the gravity data indicate the presence of a local magmatic body at mid-crustal depth in the Satpura mobile belt. The crust-ma ntle boundary is at depths varying between 40 and 44 km. The seismic-reflection data set identifies the presence of a suture at the Satpura mobile belt/Kotri-Dongargarh mobile belt boundary. A well-defined M oho offset and a pattern of adjacent fabrics, each characterized by dips to ward each other, mark tectonically imbricated crust on opposite sides of th e suture.