Oligocene-Miocene palynomorphs from subsurface sediments,West Bengal,India

Palynological studies of Cenozoic sediments from borehole PGD-1A in the easternmost extension of the Damodar Basin, West Bengal, India, provide important new palynological data from this basin, where previous data are rare. The palynoassemblage includes Striatriletes, Crassoretitriletes, Bacutriporites, Cauveripollis, Cheilanthoidspora, Palaeomalvaceaepollis, Tricollareporites, Pinuspollenites and Tsugaepollenites which suggest a late Oligocene - early Miocene age. Dinocyst genera such as Selenopemphix, Tuberculodinium, Hystrichokoipoma and Thalasiphora, recorded from the borehole, also support this age assignment. The assemblage indicates a tropical to subtropical humid climate with high rainfall. Deposition of the studied strata took place in a delta under shallow marine influence; this is the first evidence that a marine transgression extended into the Damodar Basin and that mangrove forest developed in the area.