Indian Contributions to Marine Micropaleontology (2010-2015)

Abstract

An overview of the research contributions made during the last five years by the Indian scientists in the field of marine
micropaleontology is presented. Large scale micropaleontological studies employing assemblages of various microfossil
groups (mainly foraminifera, pteropods, ostracodes and nannoplanktons) and their geochemical proxies have been carried
out on deep sea sediment cores from the Indian Ocean. These integrated studies provided better insights to our understanding
of past changes in surface and deep ocean circulations on different time scales and their relationships to seasonal variations
of monsoon climate. It was observed that the foraminiferal abundances and diversity in the Arabian Sea are mainly driven
by the variation in monsoonal intensity. Within the present day oxygen minimum zone (OMZ), benthic diversity increased
during the cold stadials when the monsoon circulation was weak, the productivity was low resulting to a weak OMZ. The
enhanced inflow of Antarctic Intermediate Water (AAIW) ventilated the deep water column during this period. In the
southern Bay of Bengal, the contribution of southern ocean deep water increased during the last glacial maximum, as
compared to the Holocene with greater influence of North Atlantic Deep Water (NADW). For the first time boron isotopebased
pCO2 of seawater was reconstructed from the eastern Arabian Sea. The results obtained have major implications in
understanding the effect of monsoon on the efficiency of carbon pump in geological records. Numerous studies have
reconstructed the variability of the Indian monsoon by using several parameters suggest a significant spatial variability of
the Indian monsoon rainfall triggered by natural and anthropogenic perturbations over different time scales.