Liptinite macerals in Singrauli coals, India: their characterization and assessment

Abstract

The record of liptinite macerals in Indian Permian coals has been uniformly quite low under normal reflected light. In fact, high inherent clastic minerals intimately associated with liptinite macerals in these coals tends to mask them, at times, completely, obstructing identification and for this reason they are considered to be poor in liptinite content. Petrographic investigations carried out on Early Permian Turra coal seam and Late Permian Jhingurdah coal seam of Singrauli Coalfield, under blue light excitation, recorded appreciably high amounts of liptinite macerals (13-57% on mineral matter-free basis) as against maximum up to 19 per cent (m.m.f basis) under normal reflected light. The liptinite macerals in these coals are formed chiefly by sporinite (7-40%) and liptodetrinite (1-16%). Cutinite, suberinite, resinite, alginate, exsudatinite and fluorinate are the other macerals of liptinite group together occurring in only subordinate amounts.

The coals of the Turra seam associated with Barakar Formation have relatively higher liptinite content than that of the Jhingurdah seam of Raniganj Formation. Such high concentration of sporinite has not been reported so far from the Indian Permian coals. The increase in liptinite/sporinite content coincides with increase in mineral matter content in many instances, i.e., dull bands normally have high liptinite content. The sporinite concentration in dull coal bands of the Permian coal seams mark the presence of semi-cannel or cannel coal bands.