Biostratigraphy and Events of Pleistocene Radiolaria in the Core ABP-06, Central Indian Ocean

Four radiolarian zones are established, viz. Buccinosphaera invaginata (NR1), Collosphaera tuberosa (NR2/3), Amphirhopalum ypsilon (NR4) and Anthocyrtidium angulare (NR5) in the core ABP-06, central Indian Ocean. The radiolarian events within the biozones are also marked. Three reworked species are noted like Spongaster pentas, Acrosphaera spinosa echinoides and Collosphaera glebulenta. In the older part of the sequence, reworking is on minor scale but more pronounced in the younger part. In the sequence studied, the base of Buccinosphaera invaginata is marked at 0.18 Ma and that of Collosphaera tuberosa at 0.5 Ma in the central Indian Ocean region. Further, it is observed that radiolarian zones NR1 and NR2/NR3 are equivalent to planktonic foraminiferal Zone N23 in the Indian Ocean.