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

Abir Gupta ¹

Affiliations
1 Publication and Information Division, CHQ, Geological Survey of India, Calcutta - 700 016, IN

Abstract

Sequence of moderately sorted siltstone to coarse grained sandstone containing abundant hummocky cross-stratified and swaley cross-stratified bedding has been described from five stratigraphic levels in a part of Barakar Formation, along the Damodar river, Ramgarh coalfield, Bihar. Scour and drape type and non-erosional based growing bed-forms, both types of hummocky crossstratification have been observed. The large dimension of hummocks, upsweeping of laminae, sigmoidal nature, broadly undulating erosive and flat base, draping and also the presence of tide influenced associated sedimentary structures, high sulphur and phosphorous content in the coal seams, high vitrinite content in the coal, absence of fining upward sequence, clay mineralogy, high concentration of chromium, similarities in trace element content with that of Assam coalfieds and presence of marine microfossils probably indicate that the observed part of Barakar Formation were deposited in an estuarine to marginal marine environment, Water depth was probably of the order of 1-30 m.

Keywords

Sedimentology, Coalfield, Barakar, Bihar.

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D. P. Das ¹, Abir Gupta ²

Affiliations
1 Geological Survey of India, Op : Orissa, Nayapalli, Unit VIII, Bhubaneswar, IN
2 Palaeontology Division - I, Geological Survey of India, 15 A & B Kyd Street, Kolkata - 700 016, IN

Abstract

This paper reports the find of a new non-mammalian cynodont from the Lower Triassic Panchet Formation of the Damodar valley, West Bengal, India. The fossil, recovered from a clay pellet rich calcareous sandstone bed, is a part of left lower jaw having five post canines that are damaged to various extents. A combination of mammal-like advanced characters such as much enlarged dentary, reduced post dentary bones, high coronoid process, large masseteric fossa, each post canine with a large central cusp flanked by a distal and a mesial accessory cusps with two additional lingually positioned cingular cusps, incipient ischolar_main division and clearly demarcated crown-ischolar_main juncture prompted to erect a new taxon Panchetocynodon damodarensis gen. et sp. nov.

Keywords

Cynodont, Lower Triassic, Panchet, Damodar Valley, India.

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