Facies characteristics and depositional environments of the Paleocene–Eocene strata of the Jaisalmer basin, western India

Abstract

The Paleocene–Eocene succession of the Jaisalmer area has hydrocarbon potential. This succession is dominantly represented by calcareous and argillaceous rocks with a subordinate proportion of arenites in the basal part. This succession is subjected for facies analysis using field characteristics coupled with petrography and we attempt to establish depositional environments based on facies analysis. A total of eight lithofacies are identified; those are cross-bedded sandstone, thinly bedded sandstone, laminated sandstone, yellow calcareous shale, chalky limestone, fossiliferous shale, fossiliferous limestone and nodular limestone. The upper Paleocene sandstones were deposited in shoreface to foreshore zones on barrier margins of a ramp/platform. The overlying lower Eocene to middle Eocene sequences containing limestone–shale alternation suggests their deposition in lagoons and tidal flats. The occurrence of ooids and peloids and diverse genera of larger foraminifera demonstrates that the deposition of carbonates took place in a tropical climatic condition. The facies associations suggest a complete 2nd order cycle of transgression–regression of the sea from shoreface to tidal flat in the Jaisalmer pericartonic basin.