Palynofloral changes in the Upper Paleozoic and Mesozoic of the Deocha-Pachami area,Birbhum Coalfield,West Bengal,India |
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Authors: | Vijaya |
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Institution: | (1) Environmental Impact & Risk Assessment Division, National Environmental Engineering Research Institute, Nehru Marg, Nagpur, Maharashtra, 440 020, India;(2) R & D Planning Unit, National Environmental Engineering Research Institute, Nehru Marg, Nagpur, Maharashtra, 440 020, India |
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Abstract: | The study of Upper Paleozoic and Mesozoic palynomorphs in three boreholes from the Deocha-Pachami area, Birbhum Coalfield,
West Bengal, India, has allowed dating of the Talchir, Barakar, Dubrajpur, and Rajmahal formations, and revealed many hiatuses.
The lowermost unit, the Talchir Formation, yielded earliest Permian palynomorphs. The Barakar Formation, which includes coal-bearing
strata, was previously dated as Early Permian. However, data presented herein indicate an Early Permian to earliest Triassic
age for this unit-containing actually the Karharbari, Barakar s.s., Kulti, and Ranigang formations as well as the basal part
of the Panchet Formation. The overlying Dubrajpur Formation is Jurassic (Callovian to Tithonian), with an unconformity at
its base. The uppermost Dubrajpur Formation is Tithonian-Berriasian. The palynomorphs from the intertrappeans within the Rajmahal
Formation suggest an Early Cretaceous age. The revised ages of the Barakar and Dubrajpur formations are of major regional
significance. The distribution patterns of spore-pollen may provide a broad spectrum of paleoclimate during Permian, Late
Jurassic, and Early Cretaceous times, as there is no record of marine signatures in the study area. |
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