Uryuzaka Formation

Invalid synonym: Aihama Formation

Type locality: Uryuzaka, Saku city - Mimakigahara, Komoro city, Nagano prefecture
Coherent formation
Inland basin-fill deposit
Pleistocene

Sedimentary facies: Lacustrine
Lithofacies: Mud, Sands, Gravels, Volcanic conglomerate, Diatomite
Lithofacies (Minor): Volcanic breccia, Scoria, Pumice
Sedimentary structures: Parallel stratification, Cross stratification

Thickness: 32 - 60 m
Upper limit: Conformity (Oishigawa Scoria), Unconformity (Iwao Formation)
Lower limit: Conformity (Nunobiki Formation)

Komoro Group
[ Upper ]
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Uryuzaka Formation
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Nunobiki Formation
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Okui Formation
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Nashidaira Formation
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[ Lower ]

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

Distribution: Uryuzaka - Aihama - Omayose, Saku city, Nagano pref.; Otome - Mimakigahara, Komoro city, Nagano pref.; Toragozen, Tateshina city, Kitasaku county, Nagano pref.
Fossils (Plants): Metasequoia disticha, Picea maximowizii
Fossils (Diatoms): Caloneis silicula, Cocconeis diminuta, Cocconeis lineata, Cocconeis placentula, Cyclotella operulata, Cymbella ehrenbergii, Cymbella lacustris, Enuotia ocellata, Epithemia alpestris, Epithemia hyndmanii, Epithemia sorex, Epithemia zebra, Gomphonema dichotomum, Melosila granulata, Navicula menisculus, Navicula pupuls, Navicula reirhardtii, Odontidium harrisonii, Odontidium mutabile, Pinnularia distinguends, Pinnularia stauroneiformis, Pleurosigma lacustre, Stauroneis phaenicenteron, Stephanodiscus aegypticus, Stephanodiscus astraea, Surirella splendida, Tabellaria fenestrata, Tetracyclus emarginatus

Kawachi and Aramaki (1979) Geology of the Komoro District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 39p. (in Japanese with English abstract 2p.)