S2 Member

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S₂ 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 (Upper): Tuff breccia
Lithofacies (Lower): Volcanic ash
Lithofacies (Lower, Minor): Accretionary lapilli
Lithofacies (Basal): Scoria fall deposit, Spatter, Lava
Sedimentary structures (Upper): Graded bedding

Source: in the vicinity of Mount Miharayama
Eruptive volume: 0.2 km³ or less
Mode of eruption: Explosion
Mode of eruption (Basal): Fissure
Thickness (Upper): A few dozen cm - Several m
Thickness (Lower): 5 - 50 cm or thicker
Upper limit: Unconformity (Y₅ Member)

S₂ Member
[ Upper ]
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Izu-Oshima S₂-c Lahar Deposit
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[ Lower ]

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 (Plants): Acer mono, Ostrya japonica, Quercus phillyraeoides?, Shiia sieboldii

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