Planktonic Foraminifera from the Neogene Volcaniclastic Sediments of South Andaman Island: Implication on Stratigraphy

The Neogene volcaniclastic sediments of South Andaman are inter-bedded with shale and siltstone; and occur as a linear band in South Andaman. Planktonic foraminiferal assemblage comprising Globigerinoides quadrilobatus triloba Reuss 1850, G. quadrilobatus altiapertura Bolli 1957, G. quadrilobatus primodius Blow and Banner 1962, G. quadrilobatus sacculifer Brady 1877, G. subquadratus Brönninman & Bermùdez, 1960, G. sicanus de Stefani 1952, Globorotalia foshi peripheroronda Blow & Banner 1966, G. scitula, G. siakensis Leroy 1939, Globorotalia sp.cf. G. opima nana Bolli 1957, G. kugleri Bolli 1957, G. sp. cf. G. scitula Brady, 1882, Globoquadrina cf. lermeuri Akers, 1955, G. altispira globosa Cushman & Jervis, G. dehiscens Chapman, Parr & Collins, 1934 and Globoquadrina sp. from the inter-bedded shale and claystone indicate early Miocene age. Neogene Archipelago Group conformably overlies the Oligocene Andaman Flysch Group without any break in sedimentation. Planktonic foraminiferal assemblage in the lower part of the sequence indicates a level near to Oligo-Miocene boundary. The thick interlayered tuff sequence of South Andaman indicates rejuvenation of arc volcanism in this region during early Miocene.