Radiolarian Biostratigraphy of Early Pliocene Sequences, Car Nicobar Island, Northeast Indian Ocean

A study of the radiolarian assemblage from the Sawai Bay Formation (Early Pliocene) exposed in Car Nicobar bland shows the presence of age diagnostic radiolarian taxa. Based on the radiolarian zonation applicable for the tropical Indian Ocean, three radiolarian zones are identified in this formation. These, in ascending order, are: Phormostichoartus doliolum zone, P. fistula zone and Stichocorys peregrina Zone. The radiolarian events (first and last appearances) recognised in the Car Nicobar sequences are discussed in relation to those in the Central Indian Ocean Basin. The proposed radiolarian zones are correlated with the previously proposed planktonic foraminiferal zone in the study area, and an htegrated biostratigraphic scheme is presented.