PERMIAN AMMONOIDS PROSTACHEOCERS AND PERRINITES FROM THE SOUTHERN KITAKAMI MASSIF, NORTHEAST JAPAN

• Published in: Journal of paleontology Vol. 79; no. 6; pp. 1222 - 1228
• Main Authors: EHIRO, MASAYUKI, HASEGAWA, HITOSHI, MISAKI, AKIHIRO
• Format: Journal Article
• Language: English
• Published: New York, USA Cambridge University Press 01.11.2005; Paleontological Society
• Subjects: Ammonoidea; Asia; biostratigraphy; Cephalopoda; Far East; Fauna; Fossils; Genera; Geological time; Geology; Honshu; Invertebrata; invertebrate; Iwate Japan; Japan; Kitakami Mountains; Kungurian; Limestones; lithostratigraphy; Massifs; Mollusca; morphology; Mudstone; paleogeography; PALEONTOLOGICAL NOTES; Paleontology; Paleozoic; Permian; Perrinites vidriensis; Prostacheoceras; Sandstones; shells; Social evolution; Sotokawame Formation; Stratigraphy; sutures; Synonyms; Tassobe Japan; Tethys; Tetrabranchiata; Japan, Honshu, Iwate Prefect., Kitakami
• ISSN: 0022-3360; 1937-2337
• DOI: 10.1666/0022-3360(2005)079[1222:PAPAPF]2.0.CO;2

Permian shallow marine strata are widely distributed in the Southern Kitakami Massif, Northeast Japan. They yield many marine fossils and have been well studied both stratigraphically and biostratigraphically. However, the geological age of the upper part of the Permian in the Tassobe district, located in the northern part of the Southern Kitakami Massif (Fig. 1), is still an unsettled question. The Permian is divided into the lower Tassobe and upper Sotokawame Formations (Okuyama, 1980; Yoshida et al., 1992). Early Permian (Sakmarian–Artinskian) fusulinoideans have been known from the middle to lower-upper part of the Tassobe Formation (Hirokawa and Yoshida, 1956; Saito, 1968; Yoshida et al., 1992), whereas no age-diagnostic fossils have been found from the overlying Sotokawame Formation. In the course of the geologic survey of the Permian, we collected two ammonoid fossils from the lower part of the Sotokawame Formation, which can provide us a basis for stratigraphic correlation. This paper describes these ammonoids and discusses their stratigraphic and biogeographic significance.