Asamigawa Formation

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Asamigawa Member (Saito, 1960) Ando et al., 1995

Type locality: Asami river, Hirono city, Futaba county, Fukushima prefecture
Coherent formation
southern Yezo Forearc basin (Jobanoki basin)
Late Cretaceous, Coniacian

Sedimentary facies: Terrestrial
Sedimentary facies (Minor): Marine
Sedimentary facies: small scale alluvial fan facing the sea
Sedimentary facies: Talus, Alluvial fan, Braided river
Sedimentary facies (Minor): Lagoon
Lithofacies: Conglomerate, Sandstone
Lithofacies (Minor): Sandy mudstone, Coaly mudstone
Lithofacies (Basal): Conglomerate
Sedimentary structures: Cross stratification

Thickness (Overall): ca. 2 - 50 m
Thickness (Basal): 0 - 24 m
Upper limit: Bottom of the marine fine sandstone bed associated with trasgressive conglomerate
Upper limit: Conformity (Obisagawa Member), Unconformity (Shiramizu Group)
Lower limit (West): Unconformity (Ohisagawa Granodiorite)
Lower limit (Southwest): Unconformity (Takakurayama Group)

Ashizawa Formation
[ Upper ]
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Obisagawa Member
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Asamigawa Member
~~~~~~~~~~~~~~
[ Lower ]

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

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

Distribution: Asami river, Hirono city, Futaba county, Fukushima pref.; Osaka, Naraha city, Futaba county, Fukushima pref.; Ashizawa - Tamayama, Ohisa town, Iwaki city, Fukushima pref.
Fossils: Pipe rocks
Fossils (Plants): Flowering plants (Flowers, Esgueiria futabaensis), Lycopods, Ferns (Spores), Conifers (Leaves, Pollen)

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.)