[ Top ] [ Japanese ]

Kashima Formation Motoyama et al., 1991

Invalid synonym: Isojirozawa Shale Formation, Kosenzawa Tuffaceous Sandstone and Shale Formation, Shirogane Formation

It had been included in Upper Yezo Group.

• Type locality: Kashima, Yubari city, Hokkaito
• Coherent formation
• Yezo forearc basin
• Late Cretaceous, Turonian - Santonian (Ammonoids)
• Late Cretaceous, Coniacian - Campanian (Foraminifera)
• Late Cretaceous (82.2 Ma, K-Ar)
• Contemporaneous heterotopic facies (West): Haborogawa Formation

• Sedimentary facies: Marine
• Depth of water: lower part of Outer continental shelf
• Depth of water: Middle - Upper bathypelagic (Foraminifera)
• Lithofacies: Massive mudstone
• Lithofacies (Minor): Sandy mudstone, Sandstone, Tuffaceous sandstone (KY-5), Felsic tuff (KY-6)

• Thickness: 2,500 m or thicker
• Upper limit: Transitional (The boundary between the sandy musdstone bed of Unit 3 and the overlying medium sandstone bed of Hakobuchi Formation)
• Upper limit: Unconformity (Hakobuchi Formation)
• Lower 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: Kashima - Mayachi creek, Mayachi, Yubari city, Hokkaito; Hobetsu river - Nutapomanai river - Bannosawa creek, Hobetsu, Mukawa city, Yufutsu county , Hokkaido
• Fossils (Ammonoids): Hypophylloceras (Neophylloceras) subramosum, Anagaudryceras sp., Gaudryceras denseplicatum, Gaudryceras tenuiliratum, Tetragonites popetensis, Mesopuzosia pacifica, Tragodesmoceroides subcostatus, Damesites damesi, Damesites semicostatus, Yokoyamaoceras jimboi, Romaniceras sp., Neomphaloceras sp., Anapachydiscus sp., Eupachydiscus haradai, Neocrioceras sp., Pachydiscidae gen. et sp. indet, Polyptychoceras yubarense, Scaphites yokoyamai
• Fossils (Inoceramus): Inoceramus teshioensis, Inoceramus tenuistriatus, Inoceramus hobetsensis, Inoceramus uwajimensis, Inoceramus pedalionoides, Inoceramus amakusensis, Sphenoceramus naumanni, Cremnoceramus mihoensis, Mytiloides cf. incertus, Magadiceramus cf. subquadratus
• Key beds: KY-5 (Tuffaceous sandstone), KY-6 (= Tomiuchibashi Tuff Member)

• 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
• Ando et al. (2007) Jour. Geol. Soc. Japan, vol.113, Supplement, pp.185-203 DOI