Crustal density model across West Bengal basin,India: An integrated interpretation of seismic and gravity data |
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| Authors: | P R Reddy N Venkateswarlu A S S S R S Prasad P Koteswara Rao |
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| Institution: | (1) National Geophysical Research Institute, Uppal Road, 500 007 Hyderabad, India |
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| Abstract: | An integrated interpretation of the seismic refraction and wide-angle reflection data, geological and structural details,
bore-hole litholog information and gravity particulars along Beliator-Burdwan-Bangaon deep seismic sounding (DSS) profile
in West Bengal basin has helped in getting a crustal density model. This model is consistent with all available surface and
bore-hole geophysical data that can realistically explain the trend, shape and magnitude of gravity data across the West Bengal
basin.
The present exercise pointed out that the thick sedimentary column (with thickening trend towards east), conspicuous lateral
variations in the Moho configuration (with a prominent 40 km wide domal feature covering the eastern part of the stable shelf
and trie western segment of the deep basinal part) coupled with the structural trends in the basement, mid and lower crustal
columns have combinedly contributed to the gravity effect and as such the prominent lateral variations in the Bouguer gravity
anomalies could be mainly attributed to regionally extending causative factors.
The synthesis clearly points out the need to take proper care in selecting the density values as direct conversion of velocities
into densities, adapting well-known conversion formulae, does not always hold good specially in the eastern part of the West
Bengal basin where a huge thickness of sediments (velocities ranging between 4 to 5 km/sec) of high density 2.6 to 2.8 g/cm3 are sandwiched between younger sediments and the crystalline basement. |
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| Keywords: | Bengal basin scarp zone middle shelf Calcutta gravity high hinge zone |
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