Lower Member

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Lower Member

Invalid synonym: Okiura Basalt Member

Type locality: Lake Nijinoko - Aseishi river, Itadome, Kuroishi city, Aomori prefecture
Coherent formation
Miocene
Intruded by: Aseishigawa Basalt, Arakawa Dolerite

Sedimentary facies: Shallow marine
Sedimentary facies (East): Submarine volcano
Lithofacies (East): Andesite lava, Pillow lava, Hyaloclastite, Andesitic scoriaceous tuff
Lithofacies (West): Shale, Siltstone
Lithofacies (West, Minor): Tuff

Thickness (East): 1,400 m or thicker
Thickness (West): ca. 170 - 400 m
Upper limit: Bottom of pumice tuff bed
Upper limit: Conformity (Nashikizawa Tuff Member)
Lower limit: Conformity (Origamizawa Formation)

Itadome Formation
[ Upper ]
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Nashikizawa Tuff Member
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Lower Member
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[ Lower ]

Kuroishi, Aomori pref.
[ Upper ]
~~~~~~~~~~~~~~
Nuruyu Formation
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Itadome Formation
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Origamizawa Formation
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Manzaemonyama Formation
~~~~~~~~~~~~~~
[ Lower ]

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

Distribution: Itadome - Lake Nijinoko, Kuroishi city, Aomori pref.; Motonagamine - Mitsumenai, Owani city, Minamitsugaru county, Aomori pref.; Izuchi, Owani city, Minamitsugaru city, Aomori pref.; Dogatai, Osawa, Hirosaki city, Aomori pref.; Jogakura valley, Aomori city, Aomori pref.; Okogawa creek, Kuroishi city, Aomori pref.; Ose river, Towada city, Aomori pref.

Takarada and Muraoka (2004) Geology of the Hakkoda San District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 86p. (in Japanese with English abstract 4p.)
Muraoka and Hase (1990) Geology of the Kuroishi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 124p. (in Japanese with English abstract 8p.)