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Ogaya Formation Yoneyama Research Group, 1973

• Type locality: Yoneyama river - Kurokawa river, Ogaya, Kakizaki, Joetsu city, Niigata prefecture
• Coherent formation
• middle - late Miocene
• Contemporaneous heterotopic facies (Upper): Oshimizu Formation
• Correlation: Teradomari Formation
• Intruded by: Chojanotebako Intrusive Rock, Hatamochiyama Intrusive Rock

• Sedimentary facies: Marine
• Lithofacies: Interbedded mudstone and sandstone, Mudstone
• Lithofacies (Minor): Acidic tuff, Andesite lapilli tuff, Limestone

• Thickness (Upper): 300 - 600 m
• Thickness (Lower): 1,000 m or thicker
• Upper limit: Conformity, partly interfingered (Oshimizu Formation), Conformity (Takegahana Formation), Unconformity (Yoneyama Formation)
• Lower limit: Conformity (Nambayama Formation)

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

• Distribution: Yoneyama river - Kurokawa river, Ogaya, Kakizaki ward, Joetsu city, Niigata pref.; Kuroiwa, Kakizaki ward, Joetsu city, Niigata pref.; Saruge river - Manzo river, Joetsu city, Niigata pref.; Tanne, Kashiwazaki city, Niigata pref.
• Tephra: Shellfishes, Calyptogena sp., Sponges (Spicules), Foraminifera
• Tephra: Nakayama Tuff, Matsudome Tuff, Kuroiwa Tuff

• Takeuchi et al. (1996) Geology of the Kakizaki District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 48p. (in Japanese with English abstract 5p.)
• Kobayashi et al. (1989) Geology of the Okanomachi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 112p. (in Japanese with English abstract 5p.)