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Younger edifice

Invalid synonym: Older Oshima Group

• Type locality: Oshima city, Tokyo
• Volcanic rocks
• Stratovolcano, Caldera volcano
• late Pleistocene (20,000 - 1,500 yBP, ¹⁴C or later)
• Contemporaneous heterotopic facies (O₁₀ Member): Sadoyama volcano

• Sedimentary facies (Minor): Lacustrine
• Sedimentary facies (Minor): Surge, Ground surge
• Lithofacies: Low-alkaline tholeiite series
• Lithofacies: Pigeonite series
• Lithofacies: Olivine basalt, Pyroxene olivine basalt, Pyroxene basalt
• Lithofacies (Upper part of a Member): Volcanic ash
• Lithofacies (Lower part of a Member): Scoriaceous lapilli, Volcanic ash
• Lithofacies (Minor): Lava, Spatter, Explosion breccia
• Lithofacies (Lacustrine): Sandstone, Siltstone
• Sedimentary structures (Lacustrine): Graded bedding, Cross stratification, Ripple marks, Loading cast

• Mode of eruption: Phreatomagmatic, Phreatic
• Eruptive volume: 40 km³
• Thickness (Lava): 1 - 4 m
• Lower limit: Unconformity (Older edifice)

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

• Distribution: Nomashi, Oshima city, Tokyo

• Isshiki (1984) Geology of the Oshima District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 133p. (in Japanese with English abstract 5p.)