Effect of igneous intrusive on coal microconstituents: Study from an Indian Gondwana coalfield

Petrological and palynological analyses of coals from two bore-holes, intruded by an igneous body (dolerite dyke), reveal characteristic changes due to thermal alteration. The unaffected coals are high volatile bituminous (Rr: 0.50-0.61%). The coals recovered from samples located close to the dyke had vitrinite with devolatization microvacuoles, higher reflectance ranging from 0.9% to 3.0% and liptinite with none to very low fluorescence. There is an increasing trend in reflectance and a decreasing trend in fluorescence in the samples occurring closer to the dyke. Presence of injected mineral matter and pyrite in the macerals further indicate the impact of thermal metamorphism on the coals occurring near the igneous body. The palynological investigation of unaffected coals shows the presence of a number of well-identified spores and pollen. However, very few palynomorphs could be recovered from coals located close to the intrusive as the pollen/spores were found to be charred beyond recognition. (C) 2010 Elsevier B.V. All rights reserved.