Insight into the structures below the Deccan Trap-covered region of Maharashtra, India from geopotential data

Abstract

Ground magnetic data collected at an average data spacing of 5 km over the Deccan Traps in Maharashtra, India are studied. In conjunction with a magnetic anomaly map generated from ground, aero and marine magnetic data, seven lineaments are identified below the Deccan Traps: six NW–SE-trending lineaments (Ln1 to Ln6) and a NE–SW-oriented lineament, Ln7. From the filtered Bouguer gravity data the sources at different depths are studied. From combined analysis we find that Ln1 coincides with the continuation of Bababudan Nallur Shear zone. The boundary between the Western and Eastern Dharwar cratons, the Chitradurg Boundary Shear, merges with Ln2. Ln3 is part of the Peninsular Lineament identified earlier. Ln4 coincides in part with the Bhima River, while Ln5 and Ln6 are possibly related to Godavari rifting. The region between Ln4 and Ln5 relates to the Kurudwadi Lineament Zone. The Kaladgi and Bhima sediments and the schist belts continue northwards below the Deccan Traps and are constrained to lie to the south of NE–SW-oriented Ln7. With the exception of Ln3 (the Peninsular Lineament) the other six lineaments below the Deccan Traps are identified for the first time. The crustal structure below the Deccan Traps that we derive from 2D modelling of combined gravity and magnetic data supports the presence of the identified lineaments.