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Saku Formation Matsumoto, 1942

Invalid synonym: Takinosawa Formation

It had been included in upper part of Middle Yezo Group.

• Type locality: Abeshinai river, Nakagawa city, Nakagawa county, Hokkaido
• Coherent formation
• Yezo forearc basin
• Late Cretaceous, Cenomanian - Turonian (Ammonoids, Inoceramus sp., Foraminifera)
• KY-4: Late Cretaceous (95.9, 93.1 Ma, K-Ar)
• Contemporaneous heterotopic facies (West): Mikasa

• Sedimentary facies: Marine
• Depth of water: Continental slope
• Depth of water: 300 - 600 m
• Depth of water (North): Upper bathypelagic
• Depth of water (South): Middle bathypelagic
• Lithofacies: Turbidite
• Lithofacies: Mudstone-dominant interbedded sandstone and mudstone
• Lithofacies (Minor): Turbidite sandstone, Tuffaceous gravelly sandstone, Felsic tuff, Sandy siltstone, Muddy sandstone (KY-4)
• Sedimentary structures: Slump structures

• Thickness: 2,300 m
• Upper limit: The boundary between the sandstone bed of Saku Formation and the overlying sandy mudstone of Kashima Formation

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

• Distribution: Teshio-Nakagawa, Tomamae, Oyubari, northern Hobetsu, Hokkaido
• Distribution: northern Hobetsu - Tosano creek, Mukawa city, Yufutsu county, Hokkaido; Mayachi creek, Mayachi - Oyubari - Shirogane river, Yubari city, Hokkaido
• Fossils: Ammonoids, Inoceramus sp., Foraminifera, Radiolarians
• Fossils (Trace fossils): Planolites
• Key beds: KY-4

• Takashima et al. (2018) Jour. Geol. Soc. Japan, vol.124, no.6, pp.381-398 DOI
• Honda et al. (2011) Jour. Geol. Soc. Japan, vol.117, no.11, pp.599-616 DOI
• Hayashi et al. (2011) Jour. Geol. Soc. Japan, vol.117, no.1, pp.14-34 DOI
• Takahashi (2010) Jour. Geol. Soc. Japan, vol.116, no.8, pp.412-417 DOI
• Ando et al. (2007) Jour. Geol. Soc. Japan, vol.113, Supplement, pp.185-203 DOI