Early Miocene Planktonic Foraminiferal and Radiolarian Zonation, Colebrook Island, Andaman Sea

Abstract

This contribution is the first of the series of investigations on integrated radiolarian and planktonic foraminiferal biostratigraphy of the Andaman-Nicobar region. Fifty species of radiolaria and thirty-one species of planktonic foraminifera have been recorded from the Early Miocene sequence exposed at Piu Bay, Colebrook Island, Andaman Sea (Northern Indian Ocean). The planktonic foraminiferal assemblage is referable to the Upper Catapsydrax dissimilis Zone and Lower Catapsydrax stainforthi Zone representing the interval from the Upper Andamanian to Lower Jarawaian Stages (Lower Archipelago Series). The radiolarian assemblage is referable to the Stichocorys wolffii Zone which corresponds with Paleomagnetic Epoch 18 with an estimated age of 18.5 to 19.5 Ma. Comparison of radiolarian and planktonic foraminiferal assemblage in the Piu Bay section with Deep Sea Drilling Project data indicate an Early Miocene age of 18.5 to 19.5 Ma.