Paleo-history of Sohagpur coal deposits in Burhar-Amalai sub-basin of Madhya Pradesh (India) through petrographic and geochemical analyses

This paper is based on the results of petrological and geochemical studies carried out on coal samples taken from Lower Gondwana coal-bearing horizons (Barakar Formation) of Sohagpur coalfield of Burhar-Amalai sub-basin of Madhya Pradesh (India). The study also shows that the coals of this basin are striated in nature and are dominated by ‘striated, striated dim’ and ‘striated bright’ components. Moreover, vitrinite (mean 33.1 vol%) and inertinite (mean 37.6 vol%) are the major maceral groups, while macerals of the liptinite (mean 5.8 vol%) group are found in relatively low content and the vitrinite reflectance (VRr) is (mean 0.48 vol%). The content of naturally associated organic components, i.e. microlithotypes, averages 76.0 vol% and inorganic i.e. carbominerite averages 24.0 vol% in this coals. Geochemically, these coals have moderately high volatile matter (mean 40.4% dry ash free basis) and ash (mean 23.7% air dry basis) content. The study also shows that the concentration of eroded macerals is particularly high in this coal of the Barakar Formation. Moreover, these coals developed in a fluvial-lacustrine environment, mainly forest swamps, where alternating oxic to mildly anoxic swamp conditions existed.