N1 Member

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N₁ Member

Type locality: Oshima city, Tokyo
Volcanic rocks
Stratovolcano, Caldera volcano
Holocene (12th century)

Sedimentary facies (Lower): Scoria cones (2 cones)
Lithofacies: Low-alkaline tholeiite series
Lithofacies: Pigeonite series
Lithofacies (Upper): Volcanic ash
Lithofacies (Upper, Minor): Accretionary lapilli tuff
Lithofacies (Lower): Interbedded scoria fall deposit and lapilli tuff, Lava (2 flow units)
Lithofacies (Lower, Minor): Reworked scoria

Thickness (Upper): 12 cm
Thickness (Lower): 730 cm or thicker
Running distance (Eastern lava): 0.9 km
Running distance (Western lava): 1.3 km
Upper limit: Unconformity (Y₆ Member)

Nomashi Formation
[ Upper ]
~~~~~~~~~~~~~~
N₁ Member
~~~~~~~~~~~~~~
N₂ Member
~~~~~~~~~~~~~~
N₃ Member
~~~~~~~~~~~~~~
N₄ 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.)