Paleogene Paleoceanography : Early Cenozoic Oceans Revisited

This paper is a review of the emerging unified view of the history of ocean circulation and climates during the Paleogene (65-24 Ma) based on evidence from many disciplines. Major threshold events at the Cretaceous/Tertiary boundary (65 Ma), in the latest Paleocene-early Eocene (53-49 Ma) and near the Eocene/Oligocene boundary (38 Ma), that profoundly affected the oceanographic/climatic history of the world ocean, are reviewed with special emphasis. Inferred global surface circulation maps are presented on paleogeographic reconstructions of the early Paleocene, middle Eocene and late Oligocene intervals. Paleogene planktonic biogeographic data (shifts of assemblages through latitudes) and oxygen-isotopic data show cooling events in middle Paleocene, middle Eocene and near the Eocene/Oligocene boundary, and a major warming event that culminated in peak warming during the early Eocene. Biogeographic data show additional cooling events in the earliest Paleocene and middle Oligocene, and a warming event in the later middle Eocene. Plankton migration data indicate that the middle Oligocene cooling episode may have been as severe as that near the Eocene/Oligocene boundary