Reworked Carboniferous palynofossils from Panna Formation, Bombay offshorebasin: Clue to a hidden target for hydrocarbon exploration

A reworked Carboniferous palynofossil assemblage from the subsurface sectio ns of the Early Eocene basal clastics of Panna Formation, Bombay offshore b asin has been discovered. This assemblage is recorded at various stratigrap hic levels of the studied well sections along with the indigenous Early Eoc ene dinoflagellate cysts and spore-pollen taxa. Initial studies have sugges ted more than one possibility of explaining the provenance of reworked sedi ments containing the Carboniferous palynofossils. One possibility is that t hese might have been derived from the erosion of Early Palaeozoic sediments present in the Deccan volcanic province. Alternatively, these sediments co uld result from long distance transport of reworked material from Saudi Ara bia-Africa region in the west which were deposited in the Bombay offshore r egion during Early Eocene. Available evidences, for and against these two p ossibilities are discussed. Our studies show that the Carboniferous reworke d assemblage is confined to the Heera-Bassein block. The reworking in the P anna Formation might have taken place by palaeorivulets cutting through the thin Deccan Trap flows, exposed in the faulted blocks. A model explaining the mechanism of reworking has been presented. Organic matter studies indic ate the presence of mature sediments below the Deccan Trap, which suggest a possible hidden basin to be a new exploration target for hydrocarbon.