Kohisagawa Member

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Kohisagawa Member Kubo et al., 2002

Type locality: Kohisa river, Ohisa town, Iwaki city, Fukushima prefecture
Coherent formation
southern Yezo Forearc basin (Jobanoki basin)
Late Cretaceous, late Coniacian

Sedimentary facies: Fluvial
Sedimentary facies (Minor): Marine
Sedimentary facies: Braided river
Lithofacies: Sandstone
Lithofacies (Minor): Conglomerate
Sedimentary structures: Cross stratification, Bioturbation, Tuff

Thickness: ca. 185 - 240 m
Upper limit: Bottom of conglomerate bed
Upper limit: Conformity (Irimazawa Member), Unconformity (Shiramizu Group)
Lower limit: Bottom of the very thick sandy siltstone-deficient sandstone bed
Lower limit: Unconformity (Kasamatsu Formation)

Tamayama Formation
[ Upper ]
~~~~~~~~~~~~~~
Irimazawa Member
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Kohisagawa Member
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[ Lower ]

Futaba Group
[ Upper ]
~~~~~~~~~~~~~~
Tamayama Formation
--------------
Kasamatsu Formation
--------------
Ashizawa Formation
~~~~~~~~~~~~~~
[ Lower ]

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

Distribution: Ohisa - Kohisa river, Ohisa town, Iwaki city, Fukushima pref.; Komatsu, Hirono city, Futaba county, Fukushima pref.
Fossils: Dinosaurs (Diplodocus sp., Teeth), Insects (in Amber), Pipe rocks
Fossils (Plants): Esgueiria sp. (Flowers), Pollen, Spores

Ando et al. (2011) Jour. Geol. Soc. Japan, vol.117, Supplement, pp.49-67 DOI
Kubo et al. (2002) Geology of the Kawamae and Ide District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 136p. (in Japanese with English abstract 6p.)