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Ichinomatazawa Basalt Member Matsukuma et al., 1971

Invalid synonym: Ichinomata basalt, Middle Member of Hayaguchigawa Formation

• Type locality: Ichinomata creek, Mase river, Hachimori, Happo city, Yamamoto county, Akita prefecture
• Volcanic rocks
• Miocene
• Correlation: Shiraishizawa Formation

• Sedimentary facies: Marine
• Lithofacies: Pillow lava, Hyaloclastite
• Lithofacies: Olivine basalt lava, Basaltic tuff breccia, Basaltic volcanic lapilli tuff
• Lithofacies (Minor): Basaltic tuff, Basaltic volcanic breccia, Acidic pyroclastic rocks, Andesitic pyroclastic rocks, Mudstone, Sandstone

• Thickness: 0 - 400 m
• Upper limit: Conformity (Tomarikawa Mudstone Member), Unconformity (Subari Andesite)
• Lower limit: Bottm of mudstone or basalt bed overlying pumice tuff at the top of main part.
• Lower limit: Conformity (Main part)

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

• Distribution: Ichinomata creek, Mase river, Hachimori, Happo city, Yamamoto county, Akita pref.; Nakashida, Hayaguchi, Odate city, Akita pref.

• Ozawa et al. (1984) Geology of the Noshiro District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 91p. (in Japanese with English abstract 9p.)
• Ozawa et al. (1983) Geology of the Nakahama District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 62p. (in Japanese with English abstract 4p.)
• Hirayama and Sumi (1963) Takanosu, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 90p. (in Japanese with English abstract 7p.)