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Otose Formation (Shibayama, 1929 ex Hanzawa, 1935) Hanzawa, 1935

Synonym: Odose Formation

Invalid synonym: Otose Green Tuff Formation

Middle - upper part is the host of bedded Mn deposits

• Volcanic rocks
• middle Miocene (20 - 16 Ma, K-Ar)
• Intruded by: Andesite dyke

• Sedimentary facies (Upper): Fluvial
• Sedimentary facies (Middle): Terrestrial
• Sedimentary facies (Lower): Marine (Shellfishes)
• Sedimentary facies: Transgressive
• Lithofacies (Upper): Andesitic pyroclastic rocks, Lava
• Lithofacies (Upper, Minor): Acidic tuff, Dacite lava
• Lithofacies (Middle): Rhyolite - dacite lava, Rhyolitic - dacitic pyroclastic rocks
• Lithofacies (Lower): Andesite lava, Andesitic pyroclastic rocks
• Lithofacies (Lower, Minor): Conglomerate, Sandstone, Mudstone

• Upper limit: Unconformity (Tanosawa Formation)
• Lower limit (Fujikuragawa Formation): Bottom of andesitic volcaniclastic rocks intercalating rhyolitic tuff and/or sandstone having clear stratification
• Lower limit: Conformity (Fujikuragawa Formation, Sasauchigawa Formation)

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

• Distribution: Fukaura city, Nishitsugaru county, Aomori pref.
• Fossils (Middle, Aniai-type flora): Plants, Freshwater diatoms
• Fossils: Shellfishes

• Sakai et al. (2019) Jour. Geol. Soc. Japan, vol.125, no.4, pp.297-305 DOI
• Hirayama and Uemura (1985) Geology of the Ajigasawa District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 86p. (in Japanese with English abstract 6p.)
• Moritani (1968) Geology of the Fukaura District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 57p. (in Japanese with English abstract 5p.)