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Obirakiyama Pyroclastic Flow Deposit (Iwai, 1965) Nagamori et al., 2013
Invalid synonym: Obirakiyama Tuff, Obirakiyama Rhyolite Member, Takedate Formation, Orakumaigawa Formation‘ĺ
- Sedimentary facies (North): Marine
- Sedimentary facies (South): Terrestrial
- Sedimentary facies: A marine embayment
- Lithofacies: Rhyolite
- Lithofacies: Pyroclastic flow deposit, Rheoigmmbrite
- Lithofacies (North): Pumiceous tuff breccia
- Lithofacies (South): Rhyolitic welded tuff (2 cooling unit)
- Lithofacies (Top): Tuff
- Thickness: 350 - 500 m
- Source: Yunosawa caldera
- Host: Lower Isodayama Formation
- Upper limit: Unconformity (Mitsumori Andesite, Nijikai Tuff, Tazawamoriyama Formation, Fujisawamori Lava, Aoni Tuff)
- Lower limit: Unconformity (Nyunai Formation, Genpachimori Formation, Origamizawa Formation, Itadome Formation, Nuruyu Formation, Kaifukiyama Dacite, Jogakura Dacite, Aseishigawa Basalt)
- Yunosawa caldera
- [ Upper ]
- ~~~~~~~~~~~~~~
- Obirakiyama Pyroclastic Flow Deposit
- ~~~~~~~~~~~~~~
- [ Lower ]
------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown
- Distribution: Mount Obiraki, Owani city, Minamitsugaru county, Aomori pref.; Takizawa creek - Magonai river, Aomori city, Aomori pref.; Takinomata river, Hirakawa city, Aomori pref.; Jogakura valley, Aomori city, Aomori pref.; Aseishi river - Aoni river, Kuroishi city, Aomori pref.
- Nagamori et al. (2013) Geology of the Aomori-Seibu District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 67p. (in Japanese with English abstract 4p.)
- 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.)