Distribution of calcareous nannofossils in Oligocene to Pleistocene sediments of the Southern Ocean

Calcareous nannofossils are generally low in abundance in Pliocene-Pleistocene sediments, whereas they are very abundant throughout the Miocene and Oligocene. Species diversity, however, is low compared with assemblages in the lower latitudes.

Nannofossil reworking is extensive in the middle Miocene at Site 751, less extensive in the lower Miocene at Site 748, and negligible for the entire Neogene at Site 747. Six nannofossil datums, which have previously been correlated with magnetostratigraphy in the Southern Ocean, were recognized in the upper Oligocene-Pleistocene sequence at Site 747. Three such nannofossil datums are available for the Neogene at Sites 748 and 751.