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Yoshinoya Formation Tokunaga, 1927

Invalid synonym: Yoshinoya Conglomerate and Sandstone Member of Nakayama Formation

• Type locality: Yoshinoya, Iwaki city, Fukushima prefecture
• Coherent formation
• southern Yezo Forearc basin (Jobanoki basin)
• early Miocene

• Sedimentary facies: Fluvial
• Lithofacies (Upper): Interbedded rhyolitic tuffaceous siltstone and sandstone
• Lithofacies (Upper, Minor): Lignite
• Lithofacies (Lower): Andesitic conglomerate, Andesitic volcaniclastic rocks, Tuffaceous mudstone
• Lithofacies (Minor): Silicified woods
• Sedimentary structures (Upper): Cross stratification
• Sedimentary structures (Lower): Imbrication, Cross stratification
• Sedimentary structures (Lower, Minor): Slump structure

• Thickness: ca. 56 - 70 m
• Upper limit: Conformity (Minamishirado Formation), Unconformity (Minamishirado Formation, Dainenji Formation)
• Lower limit (East): Conformity (Misawa Formation)
• Lower limit (West): Unconformity (Misawa Formation, Honya Formation, Kamenoo Formation, Mizunoya Formation, Goyasu Formation)

------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown

• Distribution: Yoshinoya - Kamitono - Izumi, Iwaki city, Fukushima pref.; Suetsugi - Cape Denjo, Hisanohama town, Iwaki city, Fukushima pref.; Yusuji seashore, Hirono city, Futaba county, Fukushima pref.; Mount Ishimori, Iwaki city, Fukushima pref.
• Fossils: Wood

• Ando et al. (2011) Jour. Geol. Soc. Japan, vol.117, Supplement, pp.49-67 DOI
• Kubo et al. (2002) Geology of the Kawamae and Ide District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 136p. (in Japanese with English abstract 6p.)
• Iwao and Matsui (1961) Taira and Kawamae, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 103p. (in Japanese with English abstract 17p.)