Some aspects of Plio/Pleistocene boundary - A case history from DSDP Site 217, southern Bay of Bengal

Abstract

The planktonic foraminiferal change during Pliocene/Pleistocene transition at DSDP Site 217 (Hole A) have been recorded with reference to relative family abundance; relative species abundance and frequency distribution of total planktonic foraminifera, Globorotalia menardii, Pulleniatina obliquiloculata, Sphaeroidinella dehiscens and Orbulina universa. These, along with the temporal variation in coiling direction of Gr. menardii, Globigerinoides sacculifer, Neogloboquadrina dutertrei and Pre. obliquiloculata; morphometric variation of Gr. menardii and O. universa; and changes in diversity indices viz., S, D, (H) over bar and E along the depth justify the placement of Plio/Pleistocene boundary at a depth between 23 and 22 m at Site 217 in the southern Bay of Bengal.