ORGANIC MATURATION STUDY OF PERMIAN COAL SEAMS, RAJMAHAL BASIN, BIHAR

The coals are sub-bituminous to high volatile bituminous in rank and s how evidences of ''bituminization'' stage of. maturation. They have di stinctive petrographic characteristics being rich in secondary liptini tes such as exsudatinite (nil to 7.66%), bituminite (0.94 to 28.88%) a nd fluorinite (nil to 0.99%). The rock-eval data suggest that they are hydrogen-rich and have immature organic matter-kerogen type III. The study corroborates the earlier contention regarding the onset of 'oil window' at Rom of 0.5% and suggests that the paleodepth of burial of t he coal bearing horizon in the Rajmahal basin was from 1890 to 2970m. The loss of cover has been estimated to range from 1440 to 1720m.