Information from Diatom Analysis Concerning the Eocene — Oligocene Boundary

Abstract

Publisher Summary This chapter presents information from analysis of diatom concerning the Eocene–Oligocene boundary. Diatom analysis of Eocene and Oligocene deep sea drilling project sites (DSDP) in the Atlantic and Pacific Oceans showed basic differences in the response of planktic diatom assemblages in the high southern and in the low latitudes to the tectonic, oceanographic, and climatic changes near the Eocene–Oligocene boundary. It seems that the changes in abundance, diversity, and assemblage composition of the planktic diatoms in the Late Eocene to Early Oligocene are not so much controlled by surface water temperature that changes least in the low latitudes and strongest in the high southern latitudes, but rather by the intensity of the surface water currents and the availability of nutrients. It is probable that nutrients were not a limiting factor in the high southern latitudes but that they were in the low latitudes, where regression, increased aridity, and stratification of the water column all worked toward restricting the input of nutrients into the surface water of the oceans.