PLANKTIC FORAMINIFERAL FAUNAL TURNOVERS IN THE SUBTROPICAL PACIFIC DURING THE LATE PALEOCENE TO EARLY EOCENE

Planktic foraminiferal analysis of sedimentary samples at 25-cm intervals (81 k.y.) at DSDP Site 577 provides a high resolution data base for deep-sea biostratigraphy and faunal changes during the late Paleocene to early Eocene. There are three major faunal turnovers, each of which occurred over a time period of 200 to 400 k.y., near the P3a/P3b, P6a/P6b and P8/P9 boundaries. These turnovers are characterized by rapid changes in species richness, large numbers of first and last appearances, and significant changes in the relative abundances of species. A chronological sequence of datum levels and faunal events of foraminifera tied to magnetostratigraphy provides biostratigraphic control at 1 m.y. intervals for the late Paleocene to early Eocene, with faunal and isotopic events near the Paleocene/Eocene boundary providing isochronous stratigraphic markers.