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Iwaine Formation (Imamura, 1937) Nakajima et al., 2019
Invalid synonym: Iwaine Group
- Type locality: Jinzu river, Iwaine, Osawano town, Toyama city, Toyama prefecture
- Submarine volcano in a rift zone
- Volcanic rocks
- Miocene (17.6 Ma, U-Pb; 17.3, 16.4 Ma, K-Ar, 13.6 Ma, FT)
- Correlation: Anamizu Formation, Uryu Formation
- Intruded by: Andesite dykes
- Sedimentary facies: Submarine volcano
- Sedimentary facies: Submarine volcaniclastic rocks
- Lithofacies (Upper): Andesite lava
- Lithofacies: Basaltic andesite lava, Tuff breccia, Tuff, Lapilli tuff, Volcanic conglomerate
- Lithofacies (Minor): Felsic pumice tuff, Welded tuff, Tuffaceous interbedded sandstone and mudstone
- Lithofacies (Basal): Biotite rhyolite, Hornblende rhyolite, Hornblende dacite
- Thickness: ca. 300 - 1,000 m
- Upper limit: Conformity (Iozen Formation, Kurosedani Formation, Zasunbo Alternation of Conglomerate, Sandstone and Mudstone Member), Unconformity (Orido Tuff Member, Kashinoki Conglomerate Member, Muromaki Conglomerate Member)
- Lower limit: Unconformity (Ashiu Sandstone Member, Tazo Sandstone Member, Jinzu Group, Futomiyama Group, Funatsu Granitic Rocks, Shimaji Formation)
------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown
- Distribution: Iwaine - Jinzugawa river - Shogawa river - Kubusugawa river - Joganjigawa river - Kumanogawa river, Toyama city, Toyama pref.; Shogawa town, Tonami city, Toyama pref.; Shiraiwagawa river - Mount Togariyama, Tateyama town, Nakaniikawa county, Toyama pref.
- Fossils (Upper Shellfishes): Calliostome (Tristichotrochus) sp., Calyptrea sp., Cerithedea miofluviatilis sp., Clementia vatheleti, Nassarius sp., Phaxus sp., Soletollina sp., Tellina? sp.
- Fossils (Upper, Plants): Fagus antipofi
- Nakajima et al. (2019) Jour. Geol. Soc. Japan, vol.125, no.7, pp.483-516 DOI
- Kunugiza et al. (2010) Jour. Geol. Soc. Japan, vol.116, Supplement, pp.83-101 DOI
- Nozawa et al. (1981) Geology of the Shirokimine District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 85p. (in Japanese with English abstract 10p.)
- Sumi and Nozawa (1973) Geology of the Uozu District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 104p. (in Japanese with English abstract 5p.)
- Inoue et al. (1964) Johana, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 32p. (in Japanese with English abstract 5p.)
- Sakamoto and Nozawa (1960) Yatsuo, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 69p. (in Japanese with English abstract 8p.)
- Nozawa and Sakamoto (1960) Gohyakkoku, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 68p. (in Japanese with English abstract 10p.)