Upper Oligocene-Lower Miocene diatom assemblages of the submarine Vityaz Ridge (Island slope of the Kuril-Kamchatka trench)

Abstract

The diatom assemblages of the Upper Oligocene-Lower Miocene Rocella gelida (28.2-24.0 Ma, Thalassiosira praefraga (24.0-20.3 Ma), and Thalassiosira fraga (20.3-18.4 Ma) zones established in the sed� imentary section of the southern plateau in the submarine Vityaz Ridge of the Northwest Pacific include 123 species and intraspecific taxa belonging to 55 genera. The assemblages are correlated with their coeval analogs from sections of the Northwest Pacific. Taking into consideration the fact that Lower Oligocene dia� tom assemblages were previously documented in the Vityaz Ridge area, it is assumed that the sedimentary section with wellpreserved siliceous microfossils observ able in the southern plateau of the ridge corresponds to the continuous Oligocene-Lower Miocene interval.