Nannofossil Imprints of Paleogene Transgressive Events in India

The transition from super hot Cretaceous to transient Palaeogene climate and therein reasonably fast northward movement of island Indian plate from equatorial tropics to buckling with Tibetan plate after subducting and engulfing the Tethys Sea and giving rise to lofty Himalayas, affected the oceanic current patterns and both fanua and flora drastically. These rapid tectonic processes from 65 to 50 Ma led to eustatic rise and in its response imprints could be seen in several areas of the Indian subcontinent. The calcareous nannoplankton being marine, tiny (2–10 μm), photosynthetic golden brown algae, and its fossil counterpart the calcareous nannofossils having fast turnover rate during Cenozoic are ideal as biostratigraphic markers. The Palaeogene statotypes are demarcated in Europe and biostratigraphy on varied biotic parameters were erected there but these can be well utilized in India also wherever the imprints of Palaeogene transgressions on Indian craton are recorded. After the global catastrophic late Cretaceous mass extinction around 65 Ma in which over ninetynine percent nannofossil species after gigantism died out. With the dawn of Palaeocene, new Lilliputian species evolved which grew exponentially in number and size during early Palaeogene. Massive release of greenhouse gasses at the beginning of the PETM (Paleocene Eocene Thermal Maximum) occurred and the end of PETM was met with a very large sequestration of carbon dioxide in the form of methane clathrate, coal, and crude oil which reduced the atmospheric carbon dioxide. The beginning of the Eocene Epoch indicated increased amount of oxygen in the earth’s atmosphere. At the end of the Middle Eocene Climatic Optimum, cooling and the carbon dioxide drawdown continued through the late Eocene and into the Eocene-Oligocene transition.