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Iketsuki Tuff Ishida, 1978 ex Kitamura et al., 1981

Invalid synonym: Ikezuki Tuff, Onikobe-Ikezuki Tephra, Kitagawa Dacite

• Type locality: Eai river, Iketsuki, Iwadeyama - Kawatabi, Narukoonsen, Osaki city, Miyagi prefecture
• Tephra
• Pleistocene (0.3 - 0.2 Ma; 1.7 Ma, K-Ar; 2.4 - 2.2, 0.3 - 0.15 Ma, FT; 0.26, 0.15 Ma, ESR)
• Contemporaneous heterotopic facies: Higashihara Formation

• Lithofacies: Dacite pyroclastic flow deposit (Several flow units)
• Lithofacies: Pumice tuff, Welded tuff
• Lithofacies (Lowre): Volcanic ash fall deposit
• Lithofacies (Bottom): Pumice fall deposit
• Lithofacies (Bottom, Minor): Conglomerate

• Thickness: 50 - 100 m or thicker
• Thickness (A unit): Several m
• Thickness (Pyroclastic fall deposit): 38 - 140 cm
• Area: ca. 350 km²
• Volume: ca. 18 km³ or more
• Source: Onikobe caldera
• Upper limit: Unconformity (Shimoyamasato Tuff, Nizaka Tuff, Yanagisawa Tuff)
• Lower limit: Unconformity (Onoda Formation, Takashimizu Formation)

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

• Distribution: Iketsuki - Kamiyamasato, Iwadeyama - Kawatabi, Narukoonsen, Osaki city, Miyagi pref.; Kozo - Nagasaki, Ichihasama, Kurihara city, Miyagi pref.; Hanayama, Kurihara city, Miyagi pref.; Shimaguchi, Uguisuzawa, Kurihara city, Miyagi pref.; Miyazaki, Kami city, Kami county, Miyazaki pref.

• Tsuchiya et al. (1997) Geology of the Iwagasaki District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 96p. (in Japanese with English abstract 4p.)
• Kitamura et al. (1981) Geology of the Furukawa District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 32p. (in Japanese with English abstract 4p.)