DIVERSITY OF PLANKTONIC FORAMINIFERAL ASSEMBLAGES FROM QUATERNARY SEQUENCES AT DSDP SITES 219, 220 AND 241 IN NORTHERN INDIAN-OCEAN

The Quaternary planktonic foraminiferal assemblages from DSDP Sites 21 9, 220 and 241 in Northern Indian Ocean have been analysed in terms of diversity changes along the depth of each core. For an understanding of the population dynamics in the region and its relation to the paleo climatic events (Ericson zones), relative abundance at family and spec ies levels have been studied. Different indices of diversity viz., S, D, (H) over bar and E have been worked out and correlated with that of the oscillation in paleoclimatic record, which is based on the fluctu ation in abundance of Globorotalia menardii along the depth of the cor e. It has been noted that during the Quaternary, relative abundance of different species and changes in diversity indices match well with th at of the Ericson paleoclimatic zonation, enabling recognition of diff erent stages of glacial and interglacial episodes in Northern Indian O cean.