Plankton biostratigraphy and paleoecology of the Eastern North Pacific Ocean: Introduction

Abstract

A symposium on “Eastern North Pacific Plankton Biostratigraphy and Paleoecology” was organized in order to assess the current status of plankton studies in this large region, to reconcile differing viewpoints, and to indicate areas in need of study. A review of the literature to date indicates that Upper Cretaceous strata can be zoned and correlated to the European stages by means of planktonic Foraminifera, and potentially by radiolarians and calcareous nannoplankton. The Cenozoic also could be zoned biostratigraphically using plankton, but zones have not been designated formally, although correlation between the eastern Pacific and the European Cenozoic stages is possible now. Modern oceanography and plankton biogeography in the eastern Pacific is characterized by the Transitional water mass and province, dominated chiefly by subarctic water and plankton but with admixed warmer water types. The region is biotically variable because of variable oceanographic conditions. By comparison of the modern and fossil distributional patterns, the eastern Pacific is inferred to have been influenced at least since near the end of the Cretaceous by a southward flowing current with characteristics intermediate from those of more northerly and more southerly regions.