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Odoji Formation Yagi, 1942

Invalid synonym: lower part of Ajigasawa Formation

The host of bedded Mn deposits

• Type locality: Odoji river, Fukaura city, Nishitsugaru county, Aomori prefecture
• Coherent formation
• middle - late Miocene (11.9 - 11.3 Ma, Diatoms)
• Correlation: Onnagawa Formation
• Intruded by: Rhyolite dike

• Sedimentary facies: Marine
• Sedimentary facies: Open sea (Diatoms)
• Lithofacies: Siliceous mudstone
• Lithofacies (Minor): Acidic tuff
• Lithofacies (Bottom): Glauconite sandstone

• Thickness: 30 - 200 m
• Upper limit: Transitional (Akaishi Formation)
• Lower limit: Conformity, partly unconformity (Tanosawa Formation)

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

• Distribution: Odojiyama - Isurugi - Hitotsumori, Fukaura city, Nishitsugaru county, Aomori pref.; Kurosaki - Hiroto, Fukaura city, Nishitsugaru county, Aomori pref.; Shinyu - Terasawa, Iwasaki, Fukaura city, Nishitsugaru county, Aomori pref.
• Fossils: Shellfishes (Limatula sp.), Sponges (Makiyama chitanii = Sagarites chitanii)
• Fossils (Foraminifera): Martinottiella communis, Bathysiphon sp., Cyclammina japonica, Goesella sp., Haplophragmoides trullissatum, Haplophragmoides renzi, Massilina sp., Spirosigmoilinella compressa, Martinottiella sp., Sigmoilina sp.
• Fossils (Diatoms): Actinocyclus ingens, Actinoptychus senarius, Asteromphalus sp., Coscinodiscus oculus-iridis, Coscinodiscus radiatus, Coscinodiscus stellaris, Coscinodiscus yabei (= Thalassiosira yabei), Denticulopsis hustedtii, Melosira sol, Rhizosolenia barboi, Rhizosolenia praebarboi, Rhizosolenia spp., Rutilaria epsilon, Stephanogonia hanzawae, Stephanopyxis spp., Thalassionema nitzschioides
• Fossils (Radiolarians): Eucyrtidium inflatum, Eucyrtidium asanoi, Lychnocanoma magnacornuta, Cycladophora sakaii

• Sakai et al. (2019) Jour. Geol. Soc. Japan, vol.125, no.4, pp.297-305 DOI
• Hirayama and Uemura (1985) Geology of the Ajigasawa District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 86p. (in Japanese with English abstract 6p.)
• Ozawa and Hirayama (1970) Geology of the Goshogawara District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 25p. (in Japanese with English abstract 3p.)
• Moritani (1968) Geology of the Fukaura District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 57p. (in Japanese with English abstract 5p.)