Indexed on: 28 Jun '15Published on: 28 Jun '15Published in: Journal of the Geological Society of India
The early to upper Cretaceous period, after Gondwana period, was the turning point, which continued up to middle Miocene and/or Pliocene epoch in the stratigraphic history of Peninsular India, covering the Indian shield as well as its margins. Due to creation of new low marine basins in graben-and-horst structures, the preservation of the in-situ as well as continental organisms along with rocks of petroliferous basins with their rich fossil fuel, in this country could be possible.The marine organisms flourished on the palaeocoastal river, distributor and braided channels, whereas the terrestrial plants related to angiosperms, gymnosperms and pterodophytes flourished on the swampy uplands banks, point bars and delta front areas. Over geological time, all these areas which fell within area of the low marine basin were converted into prospecting areas for oil and gas.The oil must have generated, over great length of geological time by biological conversions and chemical reactions induced by high pressure and optimum temperature. The gas must have generated from humic palynofacies and minor sapropelic components by thermal cracking. Any oil buried deeper is converted into gas by thermal cracking.The petroleum deposits marked on the basis of this theoretical model are making identical pattern of occurrences with those marked on the basis of detailed investigations by ONGC, and OIL. They are falling more-or-less on three lines drawn from the palaeo mouth of the river in the triangular area of all petroliferous basins. The new petroleum deposits, marked by cross-points on the geological maps of all available palaeocoastal river low marine basins and marginal area of palaeocontinental shelf of India, based in this theoretical model, can be investigated and explored.This picture of petroleum deposits that were generated from marine and terrestrial organisms in marine sedimentary basins is in agreement with all the observational evidence that we have today.