Otakidani Formation

[ Top ] [ Japanese ]

Otakidani Formation Sato and Hayami, 1956

Type locality: Otaki valley, Itoigawa city, Niigata prefecture
Coherent formation
Early Jurassic, Toarcian (Ammonoids)

Sedimentary facies: Marine
Sedimentary facies (Lower): Channel deposit
Lithofacies (Upper): Mudstone
Lithofacies (Upper, Minor): Sandstone, Conglomerate
Lithofacies (Lower): Conglomerate, Sandstone
Lithofacies (Lower, Minor): Sandy mudstone
Sedimentary structures (Upper): Parallel stratification, Cross stratification
Sedimentary structures (Lower): Parallel stratification

Thickness: ca. 1,500 m
Upper limit: Unconformity (Mizukamidani Formation)
Lower limit: Conformity (Shinatani Formation)

Kuruma Group (Mount Inugatake, Toyama pref.)
[ Upper ]
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Otakidani Formation
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Shinatani Formation
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Teradani Formation
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Negoya Formation
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Kitamatadani Formation
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Jogodani Formation
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[ Lower ]

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

Distribution: Otaki valley - Mount Shiratoriyama, Itoigawa city, Niigata pref.
Fossils: Ammonoids (Grammoceras sp., Hammatoceras sp.), Shellfishes (Bakevellia sp.), Plant fragments

Takeuchi et al. (2017) Geology of the Tomari District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 121p. (in Japanese with English abstract 4p.)
Takeuchi et al. (2015) Jour. Geol. Soc. Japan, vol.121, no.7, pp.193-216, DOI