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Oishi Formation Ijiri, 1941

• Type locality: Waga river, Oishi, Nishiwaga city, Iwate prefecture
• Coherent formation
• Half-graben associated with rifting of the back-arc basin (Japan sea)
• early - middle Miocene (16.0 - 13.6 Ma)
• Correlation: Kaneyama Formation

• Sedimentary facies: Marine

• Thickness: 450 - 1,100 m
• Upper limit: Conformity (Kotsunagizawa Formation), Unconformity, partly conformity (Suzukamogawa Formation)
• Upper limit: Unconformity (Oarasawa Formation), previous interpretation has been conformity or interfingered.

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

• Distribution: Waga river, Oishi, Nishiwaga city, Iwate pref.

• Hosoi et al. (2018) Jour. Geol. Soc. Japan, vol.124, no.10, pp.819-835 DOI
• Hosoi and Amano (2013) Jour. Geol. Soc. Japan, vol.119, no.9, pp.630-646 DOI
• Hosoi and Amano (2012) Jour. Geol. Soc. Japan, vol.118, no.8, pp.493-498 DOI
• Ozawa et al. (1971) Geology of the Kawashiri District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 40p. (in Japanese with English abstract 5p.)