Palynological dating of a subsurface coal bearing horizon in East Bokaro Coalfield, Damodar Basin, Jharkhand, India
Vijaya; Murthy, Srikanta; Chakraborty, B.; Roy, Joyti Shanker
published: Mar 2, 2012
The first stratigraphic borehole EBM-1 in the Muditoli block in the eastern part of the East Bokaro Coalfield, Damodar Basin, is worked out for its spore-pollen content. Gondwana sediments, approximately 1185.00m thick, comprising green shales, carbonaceous shales, sandstones and coal seams have shown many levels of changing patterns in the spore-pollen groups in the Barren Measures and Barakar formations. Between 1198.301095.25m the specimens are very dark brown and show a distorted exinal surface. The presence of radial monosaccate pollen taxa proves that this stratum is referable to the Talchir Formation, Early Permian. In the up-section, an abundance of Faunipollenites, Scheuringipollenites, Densipollenites and Striatopodocarpites is observed. The relative abundance of these taxa delimits varied levels in the palynosequence of the studied strata from 1086.95 to 13.00 m. Hence, it is inferred that these deposits contain representative palynoassemblages of Early to Late Permian age. The FADs of Lundbladispora microconata, Playfordiaspora cancellosa and Arcuatipollenites pellucidus observed at 13.00, 51.50, and 66.70m depth enhance the end of the Permian level, as these elements are the key species to mark the transition from the Permian into the Lower Triassic. Non-productive strata at varied depths in this complete succession contain an abundance of woody shreds, vegetal matter, and less of palynomorphs, maybe due to the depositional set-up within the sediments during Permian time.