Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

Indra Bir Singh ¹, V. N. Bajpai ², A. Kumar ¹, M. Singh ¹

Affiliations
1 Department of Geology, Lucknow University, Lucknow 226 007, IN
2 Department of Geology, Delhi University, Delhi 110 007, IN

Abstract

Gangetic plain shows distinct geomorphic surfaces formed in response to the climatic and base-level changes related to the sea-level fluctuations during Quaternary. Within the major river valleys, a distinct geomorphic surface (T₁) is developed, located about 5-10 m above the present-day flood plain (T₀). Study of these surfaces in the Ganga River valley near Kanpur demonstrates that T₁ -surface channel deposits assigned tentatively the date of the last interglacial (25-30 Ka) show meandering scars and coarser sediments (M₁ = 1.9 φ) than the present-day channel sands. The T₀-surface shows braided channels and finer sediments (M₁ = 3.4 φ). The Ganga River has undergone a river metamorphosis from meandering to braided-type during the last 25,000 years, accompanied by decrease in grain-size, and probable decrease in water budget and increase in sediment load. All the major rivers of the Gangetic Plain, many of them braided-type today, show evidence of having been meandering rivers during last interglacial (25-Ka).

Keywords

Geomorphology, Indo-Gangetic Plain, Ganga Pleistocene-Holocene, Quaternary Geology.

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C. L. Singh ¹, T. Lal ¹, A. Kumar ¹, S. K. Prajapati ²

Affiliations
1 Department of Geophysics, Banaras Hindu University, Varanasi - 221 005, IN
2 National Geophysical Research Institute, Hyderabad - 560 007, IN

Abstract

Gravity survey was conducted in an area of about 13000 sq km covering northeastern part of Chhattisgarh Basin, Bilaspur-Raigarh gneissic belt and the central part of Mahanadi graben. Analysis of gravity anomalies has helped in the demarcation of the boundary of Chhattisgarh Basin and Mahanadi graben as well as in the determination of extent of basins and associated structures. The thickness of sediments in Chhattisgarh Basin and Mahanadi graben is estimated to be 3 5 km and 2 5 km respectively above the crystalline basement. Two prominent gravity high closures in the vicinity of Bilaspur and Akaltra are new findings and are attributed to presence of high density metamorphic schist belt below the Chhattisgarh Basin.

Keywords

Gravity Method, Graben, Schist, Gneissic Belt, Chhattisgarh Basin.

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