Anomalous crustal and lithospheric mantle structure of southern part of the Vindhyan Basin and its geodynamic implications |
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| Institution: | 1. Geosciences Division, Physical Research Laboratory, Navarangpura, Ahmedabad 380009, India;2. Department of Earth and Climate Sciences, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune 411008, India;1. School of Earth Science and Resources, China University of Geosciences Beijing, 29 Xueyuan Road, Haidian district, Beijing 100083, China;2. CSIC-Spanish National Research Council, Barcelona, Spain;3. IGG, University of Copenhagen, Oester Voldgade 10, Copenhagen 1350, Denmark;4. Physics of the Earth, University of Zaragoza (Sciences B), Pedro Cerbuna, 12, 50009 Zaragoza, Spain |
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| Abstract: | Tectonically active Vindhyan intracratonic basin situated in central India, forms one of the largest Proterozoic sedimentary basins of the world. Possibility of hydrocarbon occurrences in thick sediments of the southern part of this basin, has led to surge in geological and geophysical investigations by various agencies. An attempt to synthesize such multiparametric data in an integrated manner, has provided a new understanding to the prevailing crustal configuration, thermal regime and nature of its geodynamic evolution. Apparently, this region has been subjected to sustained uplift, erosion and magmatism followed by crustal extension, rifting and subsidence due to episodic thermal interaction of the crust with the hot underlying mantle. Almost 5–6 km thick sedimentation took place in the deep faulted Jabera Basin, either directly over the Bijawar/Mahakoshal group of mafic rocks or high velocity-high density exhumed middle part of the crust. Detailed gravity observations indicate further extension of the basin probably beyond NSL rift in the south. A high heat flow of about 78 mW/m2 has also been estimated for this basin, which is characterized by extremely high Moho temperatures (exceeding 1000 °C) and mantle heat flow (56 mW/m2) besides a very thin lithospheric lid of only about 50 km. Many areas of this terrain are thickly underplated by infused magmas and from some segments, granitic–gneissic upper crust has either been completely eroded or now only a thin veneer of such rocks exists due to sustained exhumation of deep seated rocks. A 5–8 km thick retrogressed metasomatized zone, with significantly reduced velocities, has also been identified around mid to lower crustal transition. |
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| Keywords: | Vindhyan Basin Crustal evolution Geodynamics Heat flow Lithospheric thickness Gravity data inversion Seismic velocities |
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