Upper crustal structure in the Torni-Purnad region, Central India using magnetotelluric studies

Abstract

Magnetotelluric studies were conducted over a 100 km long NS profile in the Satpura range and Tapti basin. Data were collected at 18 stations in this region with an interstation spacing of 3-10 km. The geoelectric substructure was obtained using a two dimensional modelling technique and has indicated the presence of Deccan traps and Gondwana sediments overlying a rather complex granitic basement. Two distinct layers of Deccan basalts were delineated with a total thickness varying from 2000 m in the central part to about 300-1000 m on either sides of this NS trending profile. The thickness of the Gondwana sediments below the traps was observed to vary rather strongly in the range, 300-2000 m. Two vertical conductive zones were delineated corresponding to the Khandwa lineament and the Burhanpur tear but the sensitivity studies indicated a large degree of nonuniquness associated regarding the shape and vertical extent of these conductors. An interesting finding of these studies is the presence of a prism shaped body in the central part of the survey profile in the Satpura horst region at depths between 3.5 and 14 km with a resistivity of 20 ohm-m. The body had a lateral extent of 8 km at the top and 40 km at the bottom in the NS direction. This observation is discussed along with the other geophysical results in the Satpura and Tapti regions.