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.
