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

Invalid synonym: Shimoyamasato Tephra, Shimoyamazato Tuff

• Type locality: Shimoyamasato, Iwadeyama, Osaki city, Miyagi prefecture
• Tephra
• Pleistocene (0.29 - 0.08 Ma, TL and ESR, 0.21 Ma, FT)
• Contemporaneous heterotopic facies: Higashihara Formation

• Lithofacies: Dacite pyroclastic flow deposit (Several flow units)
• Lithofacies: Pumice tuff
• Lithofacies (Bottom): Accretionary lapilli bearing volcanic ash
• Lithofacies (Bottom, Minor): Conglomerate

• Thickness: 10 - 40 m
• Thickness (A unit): some dozen m
• Thickness (Volcanic ash): ca. 70 cm - 2 m
• Source: Onikobe caldera
• Upper limit: Unconformity (Nizaka Tuff, Yanagisawa Tuff)
• Lower limit: Unconformity (Iketsuki Tuff, Takashimizu Formation, Onoda Formation)

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

• Distribution: Kamiyamasato - Shimoyamasato, Iwadeyama, Osaki city, Miyagi pref.; Minezaki - Ichihasama river - Nakashinden, Kurikoma, Kurihara city, Miyagi pref.; Kaminuma, Hanayama, Kurihara city, Miyagi pref.; Kiyotaki, Furukawa, Osaki city, Miyagi 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.)