Antarctic Paleogene planktonic foraminifera

ODP Leg 113 drilled the first nearly continuous pre-Neogene calcareous biogenic sequence from the Antarctic Ocean at Sites 689 and 690. At 65∞S, these are probably the highest latitude calcareous sequences available in the Southern Hemisphere deep oceans. Together these two sites provide a nearly complete planktonic foraminifer history for the Late Cretaceous through late Oligocene. Planktonic foraminifers are abundant and generally well preserved from the Upper Cretaceous to the Eocene. Abundances and the quality of preservation are reduced during the Oligocene as calcareous microfossil groups are progressively replaced by siliceous groups. The Neogene is marked by only rare, isolated occurrences of planktonic foraminifers, the most conspicuous of which are of Quaternary age. […]