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Koshitomaezawa Formation Murai, 1962
Invalid synonym: Koshitomae Formation, Upper Takinoueonsen Formation
- Type locality: middle reaches of Koshitomae creek, Shizukuishi city, Iwate county, Iwate prefecture
- Coherent formation
- Miocene (ca. 8 - 6 Ma, K-Ar)
- Sedimentary facies: Marine (Shellfishes)
- Sedimentary facies: Continental shelf, Mud floor (Shellfishes)
- Lithofacies: Interbedded sandstone, siltstone and tuff
- Lithofacies (Minor): Conglomerate
- Sedimentary structures: Cross stratification
------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown
- Distribution: Koshitomae creek - Ryukawa river - Arakawa river - Sakamoto river - Shitomae river, Shizukuishi city, Iwate county, Iwate pref.; Azumai creek - Kakkonda river, Shizukuishi city, Iwate county, Iwate pref.; Obukazawa, Senboku city, Akita pref.; Sendatsu river - Akakura creek, Tazawako, Senboku city, Akita pref.
- Fossils: Fish scales, Echinoids, Bernacles (Lepas sp.), Plants, Trace fossils (Burrows)
- Fossils (Shellfishes): Lucinoma? sp., Macoma (Macoma) praetexta, Neptunea (Neptunea) cf. modesta, Nuculana (Thestyleda) nidatoriensis, Periploma sp., Portlandia (Portlandella) japonica, Serripes sp.
- Suto and Ishii (1987) Geology of the Shizukuishi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 142p. (in Japanese with English abstract 5p.)
- Kawano and Uemura (1964) Hachimantai, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 36p. (in Japanese with English abstract 8p.)