Oidegawa Formation

Type locality: Oide river, Isawa, Oshu city, Iwate prefecture
Volcanic rocks
Miocene

Lithofacies: Tuff breccia, Sandy tuff
Lithofacies (Minor): Tuffaceous sandstone, Sandy siltstone, Shale, Plagioclase rhyolite, Basaltic andesite
Sedimentary structures: Graded bedding

Thickness: 500 m
Upper limit: Transitional (Maekawa Formation), Interfingered (Nishikozawa Formation)
Lower limit: Transitional (Oarasawa Formation)

Mount Yakeishidake, Iwate pref.
[ Upper ]
~~~~~~~~~~~~~~
Mizuyama Formation
~~~~~~~~~~~~~~
Orose Formation
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Maekawa Formation
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Nishikozawa Formation
'''''''/,,,,,,
Oidegawa Formation
--------------
Oarasawa Formation
~~~~~~~~~~~~~~
[ Lower ]

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

Distribution: Oide river, Isawa, Oshu city, Iwate pref.; Upper reaches of Isawa river - upper reaches of Shitomae river, Oshu city, Iwate pref.; Upper reaches of Iwai river, Ichinoseki city, Iwate pref.; Kuwanoki creek - Karamatsu creek, Higashinaruse city, Okachi county, Akita pref.
Fossils: Barnacles, Echinoids, Brachiopods, Fish scales, Sponges (Makiyama chitanii), Foraminifera (Cyclammina japonica), Bryozoans
Fossils (Shellfishes): Chlamys cf. akitana, Chlamys cf. arakawai, Nanaochlamys notoensis, Neptunea koromogawana, Patinopecten kimurai, Phaxus sp.
Fossils (Plants): Acer sp., Ficus tiliaefolia, Pterocarya sp., Quercus sp., Ulmus sp., Vibrunum sp.

Kitamura (1965) Yakeishi-dake, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 40p. (in Japanese with English abstract 8p.)