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Usami volcano (Kuno, 1952) Oikawa and Ishizuka, 2011

Invalid synonym: Aharada Andesite

• Type locality: southeast of Mount Sukumoyama - Gyoja fall, Ito city, Shizuoka prefecture; Chojagahara, Izunokuni city, Shizuoka prefecture
• Volcanic rocks
• Stratovolcano
• Pleistocene (0.8 - 0.75 Ma)
• Intruded by: Basalt - Andesite dyke

• Sedimentary facies: Marine
• Lithofacies: Tholeiite
• Lithofacies: Olivine orthopyroxene clinopyroxene basalt, Basaltic andesite
• Lithofacies (Minor): Dacite
• Lithofacies: Basalt - Andesite lava, Scoriaceous pyroclastic breccia, Tuff breccia

• Source: east of Mount Sukumoyama
• Thickness (Lava, A unit): Several m or thicker
• Upper limit: Unconformity (Osaki volcano, Ajiro volcano, Sukumoyama volcano, Chojyagahara maar)

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

• Distribution: southeast of Mount Sukumoyama - Gyoja fall - Aharada, Ito city, Shizuoka pref.; Chojagahara, Izunokuni city, Shizuoka pref.; Usami - Tanohara, Ito city, Shizuoka pref.; Numazu city, Shizuoka pref.; Shuzenji, Izu city, Shizuoka pref.

• Oikawa and Ishizuka (2011) Geology of the Atami District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 61p. (in Japanese with English abstract 3p.)