S1 Member

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S₁ Member

Type locality: Oshima city, Tokyo
Volcanic rocks
Stratovolcano, Caldera volcano
Holocene (1,500, 1,460, 1,350, 1,330 yBP, ¹⁴C)

Sedimentary facies (Basal): Spatter rampart
Lithofacies: Low-alkaline tholeiite series
Lithofacies: Pigeonite series
Lithofacies: Pyroxene basalt, Olivine basalt
Lithofacies: Lapilli tuff, Acretionary lapilli tuff
Lithofacies (Basal): Scoria fall deposit

Source: northeast part of Izu-Oshima caldera
Eruptive volume: 0.2 km³ or less
Mode of eruption: Phreatic
Lower limit: Unconformity (S' Member)

Syn-caldera stage
[ Upper ]
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S₁ Member
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S' Member
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S₂ Member
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[ Lower ]

Oshima volcano
[ Upper ]
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Post-caldera stage
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Syn-caldera stage
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Pre-caldera stage
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[ Lower ]

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

Distribution: Oshima city, Tokyo
Fossils: Plant (Leaves)

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