Diatom biochronology of the Kuromatsunai Formation at type locality in western Hokkaido, northern Japan

Abstract

Updated chronology is presented based on diatom biostratigraphy of the upper Cenozoic Kuromatsunai Formation at the type locality, western Hokkaido, northern Japan. Two diatom zones (Neodenticula koizumii - N. kamtschatica (3.7-2.7 Ma) and Neodenticula koizumii (2.7-2.0 Ma) zones) were recognized, suggesting the Pliocene-Pleistocene boundary was strongly suggested on the outcropped depositionary site, providing a new insight into the further investigation of local responses by the global environmental change, specifically the onset of Northern Hemisphere Glaciation.