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

P. V. L. P. Babu ¹

Affiliations
1 Oil & Natural Gas Commission, Dehra Dun, IN

Abstract

Geomorphological studies south of 13th parallel in peninsular India have indicated four base levels of erosion at elevations of 900, 600, 300 and 150 metres above mean sea level. Adopting' comparative' dating method they represent the last stages of Mesozoic, Early Tertiary, Late Tertiary and Pleistocene cycles of denudation. These are correlated with the sediments deposited in the adjoining basin.

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P. V. L. P. Babu ¹

Affiliations
1 218, Lakshmi Apts ,6- 1 - 1 Padmaraonagar, Secunderabad - 500 025, IN

Abstract

The sedimentary basins of India have been geologically, geophysically and geochemically surveyed for a long time. In the course of these studies several deltaic sedimentary units are identified in the surface and subsurface areas of these sedimentary basins.

Ancient deltas are recognized in the subsurface by the presence of thick clastic sequences showing repeated cycles of upward coarsening glain size, each cycle should begin at the base with a marine shale which passes up through silts into coarser freshwater channel sands at the top. Deltaic sequence from land to sea is represented by fluviatile coastal plan, lagoonal and tidal flat complex, battier island and offshore marine shelf.

Ancient Deltas are identified in several sedimentary basins of India Jurassic to Cietaceous, Paleocene to Miocene times witnessed deltaic conditions of deposition in Jaisalmer, Kutch, Saurashtra, Cambay basins on the western part of India and Cauvery, Krishna, Godavari, Mahanadi and lower Ganga basins on the eastern part of India.

Marine shales (potential source rocks) which interfinger upslope with sandstones (potential reservoirs) in deltaic sequences (cyclically repeated) are significant in oil exploration.

Keywords

Sedimentary basins, Ancient delta, Lagoons, India.

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