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Itoo Formation Tsukano and Miura, 1954

• Type locality: Kaburaki, Minamiechizen city, Nanjo county, Fukui prefecture
• Volcanic rocks
• early Miocene (ca. 20 Ma; 17.1 Ma, K-Ar; 20.2, 18.7 Ma, FT)
• Intruded by: Suizu Granodiorite, Nogohakusan Granodiorite, Basalt - Andesite - Diorite dykes, Sills
• Correlation (Lower): Arashimadake Volcanic Rocks

• Sedimentary facies: Terrestrial, Freshwater
• Sedimentary facies: Freshwater lake, River channel, Natural levee, Flood plain
• Sedimentary facies (Middle): Turbidite
• Sedimentary facies (Middle, Minor): Pyroclastic fall deposit, Pyroclastic surge deposit
• Sedimentary facies (Lower): Scoria flow deposit
• Lithofacies (Upper): Dacite pumiceous lapilli tuff, Tuff
• Lithofacies (Upper, Minor): Volcanic conglomerate
• Lithofacies (Middle): Basalt - Andesite aa lava, Block lava, Tuffaceous sandstone Siltstone
• Lithofacies (Middle, Minor): Reworked volcanic conglomerate, Volcanic sandstone, Tuffaceous conglomerate, Dacite pumiceous lapilli tuff, Tuff
• Lithofacies (Lower): Basalt - Andesite scoriaceous lapilli tuff
• Lithofacies (Lower, Minor): Agglutinates, Lava
• Sedimentary structures (Upper, Minor): Graded bedding
• Sedimentary structures (Middle): Graded bedding, Parallel stratification, Low angle cross-stratification

• Mode of eruption (Middle, Minor): Phreatomagmatic
• Thickness: ca. 120 - 1,000 m
• Thickness (Upper): 10 m or thicker
• Thickness (Middle): Several - 30 m
• Thickness (Lower): 2 - 6 m or thicker
• Upper limit: top of dacite pumiceous lapilli tuff and tuff
• Upper limit: Conformity (Kunimi Formation), Unconformity (Kunimidake Volcanic Rocks, Higher Fluvial Terrace Deposits, Middle Fluvial Terrace Deposits)
• Lower limit: Unconformity (Nishitani Formation, Omodani Formation, Nyu Granite, Higashimata Complex)

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

• Distribution: Yokoyama - Itoo - Umeura - So - Nunogataki fall - Mount Ochisan, Echizen city, Nyu county, Fukui pref.; Kaburaki, Minamiechizen city, Nanjo county, Fukui pref.; Bushu town - Hondo town - Omi town - Betsubata town - Mount Asuwayama, Fukui city, Fukui pref.; Suizu, Tsuruga city, Fukui pref.; Mount Kuranomatayama - Kumanokogawa river - Nukumi, Ono city, Fukui pref.
• Fossils: Fish (Cyprinidae), Freshwater diatoms
• Fossils (Plants): Acer trilabatum productum, Alnus cf. firma, Betula grossa, Betula mioluminifera, Betula uzenensis, Carpinus subcordata, Celcis sp., Ficus? sp., Juglans japonica, Magnolia miocenica, Ostrya shiragiana, Platycarya miocenica, Poplunus? sp., Prunus? sp., Pterocarya cf. asymmetrosa, Pterocarya ezoana, Quercus sp., Ulmus longifolia, Zelkova ungeri

• Nakae et al. (2015) Geology of the Kanmuri Yama District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 107p. (in Japanese with English abstract 3p.)
• Nakae et al. (2013) Geology of the Imajo and Takenami District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 110p. (in Japanese with English abstract 4p.)
• Kano et al. (2007) Geology of the Fukui District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 68p.