Middle Permian fusulines from the Hoso-o Formation in Kamiyasse area, southern Kitakami Mountains, Northeast Japan: Their biostratigraphic implications.

Abstract

A fusulinid fauna, newly distinguished from the calcareous conglomerate of the Middle Permian Hoso-o Formation in Kamiyasse area, southern Kitakami Mountain, Northeast Japan, consists of Sumatrina cf. annae, Pseudodoliolina pseudolepida, Chusenella sinensis, and others. An early Midian age (late Wordian) is strongly suggestive for this fauna by the presence of Sumatrina cf. annae and the absence of both primitive forms of Neoschwagerina and Afghanella indicating an early-middle Murgabian age, and advanced forms of Lepidolina and Yabeina referable to the middle-late Midian. This age assignment of the formation by fusulinids is consistent with the previous ones by ammonoids.