Yokosawa Sandstone and Mudstone Member

[ Top ] [ Japanese ]

Yokosawa Sandstone and Mudstone Member Kanno and Arai, 1964

Invalid synonym: Yokosawa Formation

Type locality: Akikawa river, Yokosawa, Akiruno city, Tokyo
Coherent formation
middle Miocene

Lithofacies: Interbedded sandstone and mudstone, Mudstone

Thickness: ca. 350 m
Upper limit: Unconformity (Ajiro Formation)
Lower limit: Conformity (Ina Sandstone Member)

Akikawa Formation
[ Upper ]
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Yokosawa Sandstone and Mudstone Member
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Ina Sandstone Member
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Takao Tuff Member
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Tateya Mudstone Member
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Habu Tuff Member
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Kosho Mudstone Member
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Sajikami Conglomerate Member
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[ Lower ]

Itsukaichimachi Group
[ Upper ]
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Ajiro Formation
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Akikawa Formation
~~~~~~~~~~~~~~
[ Lower ]

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

Distribution: Akikawa river, Yokosawa, Akiruno city, Tokyo; Hiraigawa river, Hinode city, Nishitama county, Tokyo
Fossils (Foraminifera): Ammonia beccarii, Cassidulina sp., Globigerinoides sicanus, Globobulimina sp., Globorotalia cf. peripheroronda, Praeobulina transitoria, Sphaeroidina bulloides
Fossils (Calcareous nannofossils): Cyclicargolithus floridanus, Sphenolithus heteromorphus

Ueki and Sakai (2007) Geology of the Ome District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 189p. (in Japanese with English abstract 5p.)
Sakai (1987) Geology of the Itsukaichi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 75p. (in Japanese with English abstract 5p.)