OLIGOCENE AND LOWER MIOCENE DIATOM ZONATION IN THE NORTH PACIFIC

Abstract

This article presents the Oligocene and lower Miocene diatom zonation for the North Pacific. The data obtained in Leg 145 of the Oceanic Drilling Program (ODP) allowed a subdivision of Oligocene and lower Miocene deposits of the subarctic Pacific into seven zones. In addition, the correlation between diatom assemblages from the Komandorskie and Japanese Islands and the high southern latitudes enabled the first recognition of a lower Oligocene zone in the North Pacific (the Rhizosolenia oligocaenica Zone with the lower and upper boundaries at the levels of 33.7 and 30.2 Ma, respectively). Diatom assemblages from more than 20 sections of middle-high latitudes of the Pacific region (Kamchatka, Sakhalin, Japan, and other areas) are correlated with the suggested zonation.