Neogene Radiolarian Biostratigraphy and Paleo-Oceanography of North Boundary Currents: ABSTRACT

Abstract

Deep Sea Drilling Project (DSDP) cores from offshore Japan and California, land-based sections from California, and Holocene sediment samples from surrounding areas have been used to develop radiolarian biostratigraphies and to interpret paleo-oceanographic conditions for the Neogene of the Japan Current (a western boundary current) and the California Current (an eastern boundary current). Our studies suggest that (1) the present-day characteristics of boundary currents (western being deeper, narrower, swifter, and less productive than eastern boundary currents) have varied greatly throughout the Neogene, but are tied one to another; and (2) both mid-latitude regions can be correlated biostratigraphically to low latitudes. The Japan region is most correlative to low-latit de radiolarian biostratigraphic zones. The developed biostratigraphy of the region and inferred paleo-oceanographic trends aid in correlation of the California region to low-latitude radiolarian biostratigraphies. Comparison of material from boundary-current regions with equatorial and subpolar North Pacific DSDP material suggests that tectonic events such as the uplift of Panama may be tied to the observed Neogene changes in these boundary-current regions. These studies have also been instrumental in indicating radiolarian taxa that may be used to suggest relative paleodepth of deposition and eutrophic conditions in these boundary-current regions. End_of_Article - Last_Page 514------------