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Shibusan Formation

Synonym: Uppermost Ikeda Group (Takashimizu and Oka, 2007)

• Coherent formation
• Pleistocene
• Contemporaneous heterotopic facies: Nakazato Formation

• Upper limit: Unconformity (Kamishikaribetsu Pyroclastic Flow Deposit)
• Upper limit: Unconformity? (Kamiasahigaoka Pyroclastic Flow Deposit, Biman Gravel Bed)
• Lower limit: Unconformity (Tokachimitsumata Pyroclastic Flow Deposit), Partly unconformity (Osarushinai Formation, Oribeyama Formation)
• Lower limit: Unconformity? (Ikeda Formation)

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

• Distribution: Oribe, Kamishihoro city - Osarushinai hills, Otofuke city, Kato county, Hokkaido; Upper stream of Tokachi river, Hokkaido

• Ishii et al. (2008) Jour. Geol. Soc. Japan, vol.114, no.7, pp.348-365 DOI
• Takashimizu and Oka (2007) Jour. Geol. Soc. Japan, vol.113, Supplement, pp.65-79 DOI