Limestone-dominated Middle Permian in the northern part of the Maiya district, Southern Kitakami Massif, Northeast Japan

Abstract

Middle Permian fusulinaceans were discovered from the limestones, which have been believed to be a part of the Lower Permian Nishikori Formation, distributed in the northern part of the Maiya district, Southern Kitakami Massif. The stratigraphic unit Hatanosawa Formation is newly proposed for this Middle Permian limestone-dominated unit. The lower and upper parts of the Hatanosawa Formation are composed of massive limestone and alternating beds of limestone and calcareous shale, and the middle part consists of sandy shale and sandstone. The lower limestone contains fusulinaceans, such as Codonofusiella sp. and primitive neoschwagerinids, and the upper limestone yields Parafusulina cf. guatemalaensis, P. cf. lutugini, P. cf. motoyoshiensis, Colania cf. douvillei, and Lepidolina ? sp. Based on these fusulinaceans, the lower and upper parts of the formation are correlatable with the lower Kanokuran Series (Monodiexodina matsubaishi Zone) and upper part of the lower Kanokuran (Colania kotsuboensis Zone) to lower part of the upper Kanokuran (lower part of the Lepidolina multiseptata Zone), respectively.