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Aoni Tuff (Imaizumi, 1949) Muraoka and Hase, 1981
Synonym: Aoni Formation, Kenashiyama Volcanic Rocks
- Type locality (Outside of caldera): Todesawa creek, Araya, Hirakawa city, Aomori prefecture
- Type locality (Inside of caldera): Aoni river - Nishonai river, Kuroishi city, Aomori prefecture
- Tephra
- Pleistocene (1.7 - 1.1 Ma, K-Ar)
- Sedimentary facies (Outside of caldera): Shallow marine -Beach, Lacustrine
- Sedimentary facies (Inside of caldera): Lacustrine
- Sedimentary facies: Pyroclastic flow deposit (6 large scale sheets and 4 small scale sheets), Debris flow deposit (a sheet)
- Sedimentary facies (Inside of caldera): Underwater pyroclastic flow deposit
- Lithofacies: Tholeiite series
- Lithofacies (Outside of caldera): Interbedded pumice tuff, sandy tuff and silt, Interbedded pumice tuff, sandstone and conglomerate
- Lithofacies (Intside of caldera): Dacitic pumice tuff
- Lithofacies (Intside of caldera, Minor): Sandy tuff, Silty tuff, Diatomaceous tuff, Conglomerate, Basalt lava
- Thickness (Outside of caldera): 40 - 200 m
- Thickness (Inside of caldera): 700 - 800 m or thinner
- Source: Okiura caldera
- Upper limit: Interfingered (Okiura Dacite), Unconformity (Oguni Lacustrine Formation, Hakkoda 1st-stage Pyroclastic Flow Deposit, Hakkoda 2nd-stage Pyroclastic Flow Deposit, Minami-Hakkoda 1st-stage Lava and Pyroclastic Rocks, Rokumantai Formation, Owani Lacustrine Deposit, Okogawazawa Debris Flow Deposit)
- Lower limit: Conformity (Ikarigaseki Formation, Tazawamoriyama Formation), Unconformity (Obirakiyama Pyroclastic Flow Deposit, Nijikai Tuff)
------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown
- Distribution: Todesawa creek, Araya, Hirakawa city, Aomori pref.; Komanodai - Kroji - Teshiromori, Owani city, Minamitsugaru county, Aomori pref.; Takadate - Hanamaki - Rokumantai, Kuroishi city, Aomori pref.; Karatake - Kasesawa, Hirofune, Hirakawa city, Aomori pref.; Aoni river - Nishonai river, Kuroishi city, Aomori pref.; Takinomata river, Hirakawa city, Aomori pref.; Okogawa creek, Kuroishi city, Aomori pref.
- Fossils (Freshwater diatoms): Stephanodiscus niagarae, Stephanodiscus astraca, Stephanodiscus hantaschii, Cyclotella ocellata, Cyclotella Kützingiana, Cyclotella striata, Epithemia turgida, Fragilaria construens, Fragilaria orevistriata, Fragilaria intermedia, Achnanthes lanceolata, Rhoicospenia curvata, Cymbella lanceolata, Melosira granulata, Navicula lanceolata
- Takarada and Muraoka (2004) Geology of the Hakkoda San District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 86p. (in Japanese with English abstract 4p.)
- Muraoka and Hase (1990) Geology of the Kuroishi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 124p. (in Japanese with English abstract 8p.)