Palynology of Upper Cretaceous-Early Paleocene Deccan Volcanic Associated Sediments: Implication in Understanding Age, Climate and Depositional Environments

The Upper Cretaceous (Maastrichtian) infratrappean (Lameta Formation) and the Upper Cretaceous-early Paleocene intertrappean sedimentary beds associated with Deccan volcanic flows are windows to understand floral biodiversity, age, and paleoclimate during Deccan volcanic activity. Palynological studies of these geographically separated sedimentary beds at different stratigraphic levels show that the initiation of Deccan volcanism in the area brought climatic changes that consequently affected the biota and the depositional environments. The fluvio-lacustrine infratrappean (Lameta Formation) sediments which were deposited in a semiarid-arid climate, were having a mixture of gymnosperm and angiosperm plants. The onset of Deccan volcanic activity changed the climate and depositional environments. During the repose in Deccan volcanic activity, many small closed lakes were formed over the lava surface between the two volcanic flows. The sediments associated with these ponds have a pteridophyte-angiosperm rich flora. This vegetation is distinctly different from that of Lameta sediments. The Late Cretaceous intertrappean sediments shows dominance of palynotaxa such as Azolla cretacea, Gabonisporis vigourouxii, Aquilapollenites bengalensis, Ariadnaesporites, Farabeipollis spp. Jiangsupollis spp., Scollardia conferta, and Triporoletes reticulatus. The presence of epiphyllous fungi, algal remains (Ovoidites), pteridophytes (Azolla, Crybelosporites, Gabonisporis) and mega-plant fossils, collectively suggest the prevalence of warm, humid tropical climatic conditions. Intermittent dry spells are also indicated at many places. In the Deccan volcanic province, the Paleocene is marked by disappearance/scarcity of Maastrichtian taxa. The Paleocene vegetation is distinctly different and it shows some similarity with the Paleocene-Eocene palynoflora of western India.