On the Geology of the Environs of Kozai-mura, Igu-gori, Miyagi Prefecture

Abstract

In the present article is abridged the writer's observation on the Neogene geology of the environs of Kozai-mura, northwestern slope of the Abukuma mountain range ; with particular reference to the stratigraphical position and faunal content of the shell-beds., The order of succession of the different rocks, as observed by the writer, is as follows, in descending order., Yosigazawa shell-bed {Sandstone with fossil molluscs Conglomerate ···unconformity···Kozai shell-bed···Alternation oftuffaceous sandstone and tuffaceous shale with fossil molluscs···slight unconformity···Kanayama bed ···Shale Alternation of sandstone, shale and tuff with lignite seams and plant fossils It is now recognized that, following the deposition of the Kozai shell-bed in the shallow syncline of the Kanayama bed, the younger Yosigazawa shell-bed then was deposited over the eroded surface of the first mentioned two beds., From the molluscan assemblanges of the Kozai shell-bed and the Yosigazawa shell-bed, it appears that the former can be correlated with the Lower Sawoyama series (Moniwa beds) and the latter with the Upper Sawoyama series, in the environs of Sendai., In the northern part of Sendai, the Kozai shell-bed is probably equivalent to the Otutumi beds and the Yosigazawa shell-bed corresponds to the Aoso beds., The geological age of the Kozai and the Yosigazawa shell-bed may be Lower Miocene, in a two-fold division of the Miocene, or Lower and Middle Miocene respectively, in a three-fold division., Further the writer intends to undertaken mor advanced studies, to make clear the relationships of the different beds mentioned in this article.,