Palynostratigraphy and palynofacies of the early Eocene Gurha lignite mine, Rajasthan, India

•Palynomorphs date a 105 m section in the Gurha mine, NW India, as early Eocene.•Four palynozones document near-coastal mire and lake margin equatorial vegetation.•Abundant charcoal shows frequent wildfires in a strongly seasonal rainfall regime.•Palms, ferns, Proteaceae, Gunneraceae, Bombacaceae, and algae are represented.•Palynofacies analysis suggests fluctuating salinity and degrees of anoxia.

A 105 m early Eocene section exposed in the Gurha mine in the Nagaur-Ganganagar Basin, Rajasthan, India, archiving remains of equatorial vegetation at a time of extreme global warmth and close to the onset of the India-Eurasia collision, is investigated using palynostratigraphic and palynofacies analyses. Four palynozones e.g., Palmidites plicatus Singh, Botryococcus braunii Kützing, Triangulorites bellus Kar and Ovoidites ligneolus are identified stratigraphically on the basis of abundance of these pollen taxa over others. The occurrence of taxonomically highly diverse angiosperm pollen in all the four palynozones attests to an extremely rich near-coastal tropical flora subject to frequent wildfires under a strongly seasonal precipitation regime. Palynotaxa characteristic of these palynozones are widely distributed in other early Paleogene sediments of India. Sedimentary organic matter (structured terrestrial, biodegraded, amorphous, grey amorphous, resins, charcoal/black-brown debris and algal remains) recovered from mire and lacustrine sediments are of terrestrial origin, recording fluctuations in burial anoxia and salinity. Episodes of elevated salinity are due either to seepage of marine waters and/or a periodic excess of evaporation over precipitation at times when the depositional system was closed.