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Otori Unit (Sugimoto, 1974)

Invalid synonym: Otori Formation, Osakamoto Formation

P/T boundary (Permian/Triassic boundary) is included.

Some researchers include Kassenba Formation.

• Type locality: Akka river, Otori-Sakamoto, Akka, Iwaizumi city, Shimohei county, Iwate prefecture
• Accretionary complex
• Deposition (Chert): lateCarboniferous - early Permian, Triassic (Conodonts), late Permian (Radiolarians)
• Deposition (Siliceous mudstone): early Permian (Radiolarians)
• Deposition (Mudstone): Middle Jurassic, Bajocian - Bathonian (Radiolarians)
• Accretion: Middle Jurassic, Bajocian - Bathonian (Radiolarians)

• Sedimentary facies: Marine
• Lithofacies: Coherent facies (Chert-clastic sequence)
• Lithofacies (Upper): Sandstone
• Lithofacies (Lower, Main): Mudstone
• Lithofacies (Lower, Minor): Chert (Red chert), Red siliceous mudstone

• Thickness: 2,700 m
• Upper limit: Unknown
• Lower limit: Thrust fault

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

• Distribution: Akka river, Akka, Iwaizumi city, Shimohei county, Iwate pref.
• Fossils (Conodonts, Chert): Gondolella clarki, Gondolella gymna, Idiognathodus delicatus, Idiognathoides sinuatus, Diplognathodus atetsuensis, Diplognathodus coloradoensis, Grathodus sp. Streptognathodus elongatus, Gondolella cf. bella, Neogondolella bisselli, Sweetognathus cf. whitei
• Fossils (Radiolarians, Mudstone): Striatojaponocapsa cf. plicarum, Eucyrtidiellum sp., Eucyrtidiellum disparile, Eucyrtidiellum pustulatum, Eucyrtidiellum semifactum, Eucyrtidiellum ptyctum, Trillus cf. elkhornensis, Archicapsa pachyderma, Japonocapsa fusiformis, Striatojaponocapsa tegiminis, Striatojaponocapsa plicarum, Unuma latusicostatus, Acanthocircus suboblognus suboblongus, Diacanthocapsa? operculi, Dictyomitrella? kamoensis, Eucyrtidiellum circumpeforatum, Eucyrtidiellum disparile, Ducyrtidiellum quinatum, Eucyrtidiellum unumaense, Haliodictya hojnosi, Hexasaturnalis tetraspinus, Mirifusus cf. fragilis, Parvicingula dhimenaensis, Stichomitra? takanoensis, Striatojaponocapsa cf. plicarum

• Takahashi et al. (2016) Jour. Geol. Soc. Japan, vol.122, no.1, pp.1-22, DOI
• Ehiro et al. (2008) Jour. Geol. Soc. Japan, vol.114, Supplement, pp.121-139 DOI
• Suzuki et al. (2007) Jour. Geol. Soc. Japan, vol.113, no.6, pp.274-277 DOI