Insight into the structures below the Deccan Trap-covered region of Maharashtra, India from geopotential data
Mita Rajaram, S. P. Anand, V. C. Erram, B. N. Shinde, 2017. "Insight into the structures below the Deccan Trap-covered region of Maharashtra, India from geopotential data", Tectonics of the Deccan Large Igneous Province, S. Mukherjee, A. A. Misra, G. Calvès, M. Nemčok
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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.
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Understanding the Deccan Trap Large Igneous Province in western India is important for deciphering the India–Seychelles rifting mechanism. This book presents 13 studies that address the development of this province from diverse perspectives including field structural geology, geochemistry, analytical modelling, geomorphology and geophysics (e.g., palaeomagnetism, gravity and magnetic anomalies, and seismic imaging). Together, these papers indicate that the tectonics of Deccan is much more complicated than previously thought. Key findings include: the Deccan province can be divided into several blocks; the existence of a rift-induced palaeo-slope; constraints on the eruption period; rift–drift transition mechanisms determined for magma-rich systems; the tectonic role of the Deccan or Réunion plumes; sub-surface structures reported from boreholes; the delineation of the crust–mantle structure; the documentation of sub-surface tectonic boundaries; post-Deccan-Trap basin inversion; deformed dykes around Mumbai, and also from the eastern part of the Deccan Traps, documented in the field.