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

A. T. R. Raju ¹, M. R. Rao ¹

Affiliations
1 Institute of Petroleum Exploration, Dehra Dun, IN

Abstract

The depositional environments of Eocene oil and gas productive sands in Anklesvar field, which are referred to as middle and upper sands, have been studied from three main Jines of investigation, namely litho-associations, petrography and textural attributes. The middle and upper sands show subtle differences in their associational characters, petrographic features and size distributions. The middle sands, appear to have been deposited along distributory channels, over inter channel tidal flats and along tidal inlets in a tidal estuary. The upper sands, belonging to Upper Eocene, were probably deposited along a barrier beach in a transgressive open marine environment.

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M. R. Rao ¹

Affiliations
1 Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow - 226 007, IN

Abstract

Palynological study of the Miocene sediments exposed along Kullur-Kavur Road section, Mangalore, Karnataka revealed the occurrence of 11 genera and 16 species of reworked palynofossils. Of these, Permian palynotaxa (8 genera and 11 species) are better represented than the Cretaceous ones (3 genera and 5 species). The important reworked palynotaxa are Parasaccites, Striatopodocarpites, Rhizomaspora, Scheuringipollenites, Callialasporites and Alisporites and these palynomorphs usually occur in Palaeozoic and Cretaceous rocks and do not extend to Tertiary. Based on the reworked palynofossils, occurrence of Permian and Cretaceous deposits in Mangalore basin has been postulated. The occurrence of reworked palynofossils might have been derived by the erosion of some Palaeozoic and Mesozoic sediments existing at the time of sedimentation. Presence of huge Permian sediments in western India, which could have been the other source for the reworked palynomorphs. The other possibility is that these fossils might have also come from Middle East Countries. Permian and particularly the Mesozoic rocks are well developed in these countries and of the Mesozoic rocks are abundantly rich in oil Sediments. These sediments could have eroded and redeposited in the eastern coast of the Arabian sea.

Keywords

Reworked Permian and Cretaceous Palynofossils, Miocene, Mangalore, Karnataka.

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D. V. Reddy ¹, P. Nagabhushanam ¹, M. R. Rao ², D. S. Mitra ³, B. M. Tripati ³, S. K. Sinha ³, B. Bhadu ³

Affiliations
1 National Geophysical Research Institute (Council of Scientific and Industrial Research), Uppal Road, Hyderabad - 500 606, IN
2 Oil and Natural Gas Corp. Ltd., 9 Kaulagarh Road, Dehra Dune- 248 195, IN
3 Oil and Natural Gas Corp. Ltd., 9 Kaulagarh Road, Dehra Dune - 248 195, IN

Abstract

The Oil and Natural Gas Corporation Limited (ONGC), India, embarked upon exploration and exploitation of deep groundwater under the project named as "Saraswati" in arid Thar desert, Rajasthan, with a societal mission of providing water to the local people and cattle. A 555 m deep well drilled by the ONGC near Jaisalmer town in 2006 encountered a potential aquifer at a depth of 450-500 m. Radiocarbon dating of this well water indicated paleorecharge to be >40,000 yr BP (uncorrected) (Before Present with respect to 1950 AD), while the medium depth (∼200 m) well waters around that area showed an age range of ∼9,000 to 17,000 yr BP (uncorrected). These waters represent pre-Saraswati era recharge, because the mighty Saraswati flowed in this region between 7000-4000 yr BP. The stable isotope (δD and δ¹⁸O) and Total Dissolved Solids (TDS) data of these waters clearly indicated absence of communication between the two aquifers (deep and medium depth). However, the extension of this deep aquifer needs to be determined.

Keywords

Groundwater, Paleo-Recharge, Radiocarbon, Aquifer, Rajasthan.

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