Itaoroshitoge Siltstone Member

Itaoroshitoge Siltstone Member (Okutsu, 1955) Kitamura et al., 1983

Invalid synonym: Itaoroshitoge Formation, Itaoroshitoge Tuff and Shale Member

Type locality: The confluence of Hirose river and Okura river, Shirasawa, Aoba ward, Miyagi prefecture
Coherent formation
late Miocene

Sedimentary facies: Lacustrine
Lithofacies: Tuffacesous siltstone, Pumice tuff (Obsidian-bearing), Tuff, Sandstone
Sedimentary structures (Sandstone): Cross stratification

Thickness: ca. 25 - 150 m

Shirasawa Formation
[ Upper ]
~~~~~~~~~~~~~~
Itaoroshitoge Siltstone Member
--------------
Baba Tuff Member
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Shirasakatoge Siltstone Member
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Hirutadaki Tuff Member
--------------
[ Lower ]

Akiu Group
[ Upper ]
~~~~~~~~~~~~~~
Shirasawa Formation / Mitaki Formation
--------------
Nashino Formation
~~~~~~~~~~~~~~
Yumoto Formation
~~~~~~~~~~~~~~
[ Lower ]

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

Distribution: The confluence of Hirose river and Okura river, Shirasawa, Aoba ward, Miyagi pref.
Fossils: Diatoms (Aulacosira granulata)
Fossils (Upper Neshiroishi flora): Betula? sp., Carpinus subyedoensis, Castanea sp., Fagus palaeocrenata, Fraxinus sp., Magnolia sp., Paliurus sp., Quercus (Cyclobalanopsis) cf. praegilva, Sequoia sp., Zelkova serrata, Zelkova ungeri

Kitamura et al. (1986) Geology of the Sendai District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 134p. (in Japanese with English abstract 9p.)
Kitamura et al. (1983) Geology of the Yoshioka District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 50p. (in Japanese with English abstract 5p.)