An integrated crustal model along Nagaur - Jhalawar geotransect

Abstract

An integrated crustal density model along Nagaur-Jhalawar geotransect across the Aravalli fold belt is constructed based on the modelling of gravity data using the constraints from deep seismic reflection profiling results and near-surface geology. The observed gravity field along the transect shows high Bouguer and Free-air anomalies over the fold belt and lows on its flanks over the Marwar and Vindhyan basins. Results of 21/2 dimensional gravity modelling indicate that the gravity high in the central part of the profile is partly due to a prismatic shaped high density body (3.09 g/cm 3 ) in the lower crust extending from 18 km upto 45 km and partly due to the exposed high density metasediments of Delhi and Aravalli fold belt. The lows on the flanks have been attributed mainly to the presence of low density granites and sediments. The resultant crustal density model shows high density basement and lower crust underlying the adjoining Marwar basin in the west and Vindhyan basin on the east of fold belt. The large-scale thrusting of rocks along shear and fault zones from east to west might have resulted from continental collision during Proterozoic period.