We present a micropaleontological re-examination of the depositional environment of the Kojyakui-sho sediments of the Middle Miocene Obata Formation, part of the Tomioka Group, located along the Kabura-gawa River near Tajima, Tomioka City, western Gunma Prefecture, central Japan. These sediments contain sublittoral and bathyal ostracods, and were deposited in the bathyal zone on a quartz-porphyry bedrock seafloor during the late Early to early Middle Miocene. Planktonic foraminifera and ostracods within these samples indicate that the Kojyakui-sho sediments formed during the Miocene Climatic Optimum; this is the second reported occurrence of these Miocene Climatic Optimum bathyal ostracod species in Japan.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.