Hydrocarbon Potential and Source Vegetation of Early Paleogene Lignite-bearing Sequences from Western India

Equatorial position of Indian subcontinent during Early Paleogene time supported the proliferation of thick vegetation that caused the formation of several lignite sequences in the entire western India. In the present study we integrate organic geochemical investigation with palynofloral findings to unveil the history of the source of these lignite-bearing sequences along with their capacity of hydrocarbon generation. Organic geochemistry includes Rock Eval pyrolysis, in order to reveal the thermal maturity as well as characterization of kerogen type and the identification of biomarkers by GC-MS technique for tracing the source of these lignite horizons. Lignites, shales and fossilized resins from the two mines of Rajasthan and Cambay Basin, western India have been analysed. Rock Eval pyrolysis data shows that the organic matters are thermally immature and the sediments are capable to produce mix oil and gas whereas fossilized resins can generate oil upon maturation. The deposition of these lignite formations took place in the marginal marine setting which is confirmed by the dominance of mangrove pollen. Biomarker and palynological investigation together reveals that the source of the lignites of Cambay Basin are dominated by angiosperm family whereas both angiosperm and gymnosperm signatures have been encountered from Rajasthan Basin.