Early Permian (Artinskian and Kungurian) Fusulines from the Nakadaira Formation in the Kamiyasse Area, Southern Kitakami Mountains, Japan

Abstract

Fourteen species of early Permian (Artinskian and Kungurian) fusulines are described from the upper part of the Nakadaira Formation in the Kamiyasse area, South Kitakami, Japan, correlatable to the upper part of the Sakamotozawa Formation in the type area. Among them, Praeparafusulina pseudojaponica, Juresanella juresanensis, and Juresanella uralensis diagnostic in the Nakadaira Formation are uncommon or absent in seamount-originated limestones of the Permian and Jurassic terranes of Japan, and important paleobiogeographically. Darvasella kitakamiensis sp. nov. is distinguished from the known species of the genus by its more regularly folded septa and the presence of axial fillings. Based on these fusulines, the uppermost part of the Nakadaira Formation is correlated to the Artinskian/Kungurian of Cisuralian, suggesting that the carbonate facies having early and most middle Guadalupian fusulines is not developed in the Kamiyasse area, as well as probably throughout the southern Kitakami.