Fusuline foraminifera from the basal part of the Sakamotozawa Formation, South Kitakami Belt, Northeast Japan

概要

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A small fusuline fauna, composed of Schubertella sp., Quasifusulina? sp., Rugosofusulina sp., Eoparafusulina aff. perplexa (Grozdilova and Lebedeva), and Nipponitella explicata Hanzawa, is described for the first time from the basal part (Sa member) of the Sakamotozawa Formation in the type (Nagaiwa) area, South Kitakami Belt, Northeast Japan. The fauna is somewhat similar to that from the lower part of the overlying Sb member with a Sakmarian age, but lacks Robustoschwagerinanunosei (Hanzawa), which is biostratigraphically the most significant fusuline species of the latter. This faunal similarity, together with conformable stratigraphic relationship between the Sa and Sb members, suggests that the present Sa fauna is also highly probably referable to the Sakmarian. It is further concluded that the base of the Sakamotozawan Stage widely used in the regional Permian chronostratigraphic subdivisions of Japan broadly coincides with that of the Sakmarian in the standard international chronostratigraphic scale of the Permian System.
新潟大学の論文
2007-03-31