Carboniferous Foraminifers of the Lower Part of the Ichinotani Formation, Hida Marginal Terrane, Japan

Abstract

Abstract. The Ichinotani Formation distributed in the Fukuji area, Hida Marginal Terrane, central Japan, consists of fossiliferous bedded limestone intercalating reddish mudstone and sharpstone conglomerate with a continental margin affinity. The lower part of the formation in the studied area is subdivided into five fusuline zones from lower to upper, Eostaffella kanmerai, Pseudostaffella antiqua, Pseudostaffella kanumai, Profusulinella fukujiensis, and Profusulinella dagmarae. These five zones are probably correlated to the Visean/Serpukhovian (Venevian/Tarusian), middle part of the Bashkirian (Akavasian), middle to upper part of the Bashkirian (Askynbashian to Tashatinian), upper part of the Bashkirian (Tashatinian to Asatausian), and uppermost Bashkirian (Asatausian), respectively, of the stratotypes of the Russian Platform and the South Urals based on the biostratigraphy, faunal composition and correlation of foraminifers. There are remarkable faunal transitions between the Eostaffella kanmerai and Pseudostaffella antiqua zones. Almost coeval Pseudostaffella–Profusulinella assemblages are recognized between the upper part of the Lower Member and the lower part of the Middle Member in the type section of the Ichinotani Formation. Thirty-three species of foraminifers are paleontologically noted and compared to those mainly of the type materials and the taxa to have been described from the Ichinotani Formation.