Pliocene (Upper Mizuho) Foraminifera from Japan (Preliminary Report)

Abstract

In the present article, the writer has attempted to give an account of a preliminary survey of the Pliocene Foraminifera from Japan., The materials examined are derived from many geographically isolated localities, and are classified into the following 18 faunal associations., (A) Foraminifera-Province of the Japan sea (Ura-Nippon) type., Of many different species of Foraminifera distinguished up to the present time from the Japanese Pliocene, some species are found to be short-lived and distributed only in the northern Japan (Ura-Nippon), and are not known from the Pacific side of Japan., These characteristic species are listed in Table 3., In the present province, 9 faunal associations are included., 1., Anden association., A study of Foraminifera collected from the Pliocene of the Oga Peninsula has led the writer to the recognition of three foraminiferal associations., Anden association comprises the fauna of the Sibikawa beds as defined by OHASI and TOYAMA., 2., association is for the Foraminifera fauna of the Wakimoto sandy shale defined by OHASI and TOYAMA., 3., association comprises the fauna from the Kitaura beds as defined by OHASI and TOYAMA in Oga Peninsula and Taya beds of K., HATAI in Iwami-Sannai-mura, Kawabe-gun, Akita prefecture., 4., Setana association is divided into three subassociations-Kuromatunai, Hanaisi and Setana ; the faunule from the districts of Hanaisi and Setana, composed of several characteristic forms of the Cassidulinidae and Polymorphinidae, should be considered to mark the northern limits of the Cassidulina province of the Japan Sea type, and may be correlated to the and Daisyaka associations, while that from Kuromatunai is related to both the Japan Sea and Pacific types, and may be comparable with the Anden association in Oga Peninsula or Naganuma association in the Miura Peninsura., 5., Daisyaka association is from a comparatively coarse grained sandstone exposed in the region of Utimanbegawa, Higasi-Turuga-gun, Aomori prefecture; the fauna seems to be closely related to that of association on one hand and that of the or on the other., 6., The materials of the association are derived from Natukawadani and Simotaka-mati, Kitadyo-mura, Kariha-gun, Niigata prefecture, both belonging to the Natukawa beds as defined by OMURA and CHITANI., 7., Sawane association from the Pliocene of Sawane, Sado Island, may be correlated to the association., 8., association comprises the fauna of the Tagawa beds as defined by T., ONOYAMA., It may be slightly younger than the or which are widely distributed in the Provinces of Kaga, Noto, Etizen and Etigo, and should be correlated to that of Anden in Oga Peninsula., 9., association is for the Foraminifera fauna of the Onma beds defined by T., ONOYAMA., It is closely related to that of and also to those of Kakegawa in Sizuoka prefecture., (B) Foraminifera-Province of the Pacific (Omote-Nippon) type., The fossils of the Nodosariidae found in the Neogene of Japan mostly belong to recent species, but there are many forms not hitherto recorded from the surrounding seas., Of them, 18 species ; namely Robulus costatus (F., & M., ), R., costatus subdecoratus (CUSHMAN), R., costatus multicostus (CUSHMAN), R., abensis ASANO, R., papillosus (CUSHMAN), R., tumidus ASANO, R., surugaensis ASANO, R., calcarioides ASANO, R., bicostatus ASANO, Pianularia japonica (ASANO), P., kakegawaensis (ASANO), P., boso ASANO, P., yabei ASANO, Lenticulina kamakuraensis ASANO, Vaginulina boso ASANO, V., miuraensis ASANO, V., awaensis ASANO, V., tibaensis striata ASANO are distributed only in the Pliocene of the Pacific side and not known from the Japan Sea side. [the rest omitted]