A study of geochemical and petrographic characteristics of Eocene coal from Bapung coalfield, East Jaintia Hills, Meghalaya, North East India

The Bapung coalfield in the East Jaintia Hills of Meghalaya was studied in order to know the physicochemical character and depositional environment of the coal-based on geochemical and petrographic analysis. The Bureau of Indian Standards procedure followed for proximate and ultimate analysis. Whereas for petrographic analysis, polished blocks were studied under reflected light with an oil immersion lens using a Leitz microscope (magnification × 200) following the ICCP system. The study reveals that the coal has low ash (1.1 to 4.2%), low moisture (1.5 to 2.1%), high volatile matter (40.02 to 45.25%), high carbon (74.30 to 79.65%), high hydrogen content (more than 5%), and high sulphur above 3%. In reflected light, the dominant maceral identified is vitrinite (75.5 to 82.6%), while inertinite occurs in subordinate amounts, and liptinite concentration is low. This coal is sub-bituminous A to high volatile bituminous C in rank. The petrography-based ternary facies model used to decipher the paleodepositional environment suggests that anoxic condition dominantly prevailed in the paleomire, and there was an association of peat with brackish water condition that allowed the sulphate-reducing bacteria to thrive.