Microfossil age of the Miocene sequence exposed along the Kinugawa River, Utsunomiya City, Tochigi Prefecture, central Honshu, Japan.

Abstract

An upper Miocene sequence is newly discovered at the western part of the Kinugawa Lowland, Tochigi Prefecture, central Honshu, Japan. We examined microfossil biostratigraphy of the Miocene siltstone exposed at the small outcrop along the Kinugawa River. Planktonic foraminifera and calcareous nannofossils were detected from the siltstone. The present sequence corresponds to the planktonic foraminiferal zone N.16 and calcareous nannofossil zones CN6-CN7b, and should be correlated with the upper part of the Arakawa Group distributed at the eastern part of the Kinugawa Lowland.