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

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 sedimentary 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 diatom assemblages were previously documented in the Vityaz Ridge area, it is assumed that the sedimentary section with well-preserved siliceous microfossils observable in the southern plateau of the ridge corresponds to the continuous Oligocene-Lower Miocene interval.