Some aspects of the physical constitution of certain lower Gondwana coal seams of India

The vast majority of Lower Gondwana Barakar coal seams investigated reveal microfragmental character of organic matter rich in durain and duroclarain lithotypes with few thin vitrain bands. They are characterized by fine state of maceral division with significant proportion of sedimentary mineral matter. Inertinite (fusinite, semifusinite and micrinite) is predominant in the coal seams forming 50 to 60 percent of the maceral composition. The distribution pattern of the physical constituents of the coal shows characteristic petrographic assemblages or types indicating many features, which deserve attention during rehabilitation of the material. Predominant fusinization of fossil material and finely dispersed clay minerals suggest decay and decomposition of swamps in addition to peatification. The differing degrees of exposure of organic material may be due to lower ground water level than swamps, indicating drier conditions during the initial phase of coal formation. Subsequent coalification and regional variation in coal types may be explained on the basis of stratigraphic depth and certain igneous rocks commonly seen in the coal seams.