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Authors
Affiliations
1 Department of Botany, University of Calcutta, Kolkata - 700 019, IN
2 Department of Botany, City College, Kolkata - 700 009, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 65, No 4 (2005), Pagination: 411-427
Abstract
Palynostratigraphic analyses of the Lower Gondwana sediments in the Saharjuri basin, Deoghar group of coalfields, Jharkhand recognize fifteen palynostratigraphic zones (PNSJ T, PNSJ 1 - XIV).The palynostratigraphic zones have been compared with the known lithostratigraphic zones of the basin and suggest upper Karharbari Formation for the Saharjuri coal seam nos. CH. I - II and Barakar Formation for the rest of the coalseams viz., Colony to Damagara CH.III- CH.XIV.
Each of the palynostratigraphic zone represents a characteristic ecological phase of deposition. The palynostratigraphic zones have been identified on the basis of the stratigraphically restricted occul-rence of quantitatively dominant and qualitatively significant taxa in the palynoassemblages. Altogether fifteen such zones are recognised viz., Ecol. Ph. PNSJ T and I-XIV. These fifteen Eco- palynostratigraphic zones were deposited under the influence of major climatic phases viz. cool climatic phase (C1. Ph. I), temperate climatic phase (C1. Ph. II) and warm climatic phase (C1. Ph. III). The temperate climatic phase C1. Ph. II is the most prolonged phase of deposition in the Saharjuri basin; this phase however has record of three minor but distinct sub-phases of climatic fluctuations. The sub-phases are stratigraphically restricted and represent characteristic palynoassemblages. One of the ecological phases viz., Ecol. Ph, PNSJ XII is distinct from the other ecoassemblages in the qualitative and quantitative abundance of taxa of brackish to marine environment. This minor phase of deposition is identified as Marine Transgression in the essentially continental facies of deposition. The stratigraphic horizons with characteristic assemblage of clearly distinguishable minor Eco-Climatic zones are identified as 'Marker Horizons'.
The major and minor climatic phases, sub-phases, ecological phases of Marine Transgression, identified as the Marker Horizons in the Saharjuri basin closely correspond with the similar sequential changes of climatic and ecological phases of Marker Horizons in the adjoining Rajmahal basin and other basins of India and Early Permian of Bhutan in the eastern Indian subcontinent.
Keywords
Palynostratigraphy, Major-Minor Climatic- Ecological phases, Marine influence, Marker Horizon, Barakar Formation, Late Early Permian, Indian Lower Gondwana, Saharjuri basin, Jharkhand.
