SOME ASPECTS OF PLIO PLEISTOCENE BOUNDARY - A CASE-HISTORY FROM DSDP SITE-217, SOUTHERN BAY OF BENGAL/

The planktonic foraminiferal change during Pliocene/Pleistocene transi tion at DSDP Site 217 (Hole A) have been recorded with reference to re lative family abundance; relative species abundance and frequency dist ribution of total planktonic foraminifera, Globorotalia menardii, Pull eniatina obliquiloculata, Sphaeroidinella dehiscens and Orbulina unive rsa. These, along with the temporal variation in coiling direction of Gr. menardii, Globigerinoides sacculifer, Neogloboquadrina dutertrei a nd Pre. obliquiloculata; morphometric variation of Gr. menardii and O. universa; and changes in diversity indices viz., S, D, (H) over bar a nd E along the depth justify the placement of Plio/Pleistocene boundar y at a depth between 23 and 22 m at Site 217 in the southern Bay of Be ngal.