NEOGENE PLANKTIC FORAMINIFERAL BIOCHRONOLOGY OF THE CENTRAL INDIAN-OCEAN DSDP SITE-237 AND SITE-238

Qualitative and quantitative planktic foraminiferal analyses of the Ce ntral Indian Ocean DSDP Sites 237 and 238 provided 34 important events during the Neogene. A comparison of the chronological succession of t hese planktic foraminiferal events, with the other tropical Indian Oce an and Southwest Pacific DSDP Sites reveals remarkable similarity. The refore, these Neogene foraminiferal events [First Appearance (FA) and Last Appearance (LA)] are considered as synchronous within the tropica l Indo-Pacific except Gq. dehiscens LAD, Gr. margaritae FAD, range of Gr. tumida flexuosa, Gr. crassaformis FAD, Gr. truncatulinoides FAD, a nd Gs. obliquus LAD, which are diachronous reflecting their paleobioge ographic control. Stratigraphic ranges of planktic foraminifera enable d recognition of 20 zones from the late Early Miocene to Pleistocene. Two hiatuses (NH3 at Site 238 and NH4 at Site 237) associated with sev ere carbonate dissolution were identified. These hiatuses have also be en recorded at abo ut the same stratigraphic intervals in several deep sea sections in the Pacific and represent an important oceanographic event, useful for interoceanic correlation.