Yuba Formation

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Yuba Formation

Type locality: Oshima city, Tokyo
Volcanic rocks
Stratovolcano, Caldera volcano
Holocene

Lithofacies: Low-alkaline tholeiite series
Lithofacies: Pigeonite series
Lithofacies:

Lower limit: Unconformity (Nomashi Formation)

Yuba Formation
[ Upper ]
~~~~~~~~~~~~~~
Y₁ Member
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Y₂ Member
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Y₃ Member
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Y₄ Member
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Y₅ Member
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Y₆ Member
~~~~~~~~~~~~~~
[ Lower ]

Post-caldera stage
[ Upper ]
~~~~~~~~~~~~~~
Yuba Formation
~~~~~~~~~~~~~~
Nomashi Formation
~~~~~~~~~~~~~~
[ Lower ]

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

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

Distribution: 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.)