Ikego Formation

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Ikego Formation Ueda, 1930

Invalid synonym: Ikego Pyroclastic Formation

Type locality: northeast of Jinmuji, Zushi city, Kanagawa prefecture
Coherent formation
Pliocene
Correlation: Hatsuse Formation, Anno Formation

Sedimentary facies: Marine
Sedimentary facies: Forearc basin deposit
Depth of water: upper - middle bathyal (Foraminifera)
Depth of water: 500 - 2,000 m (Foraminifera)
Lithofacies: Tuffaceous mudstone, Tuffaceous sandstone, Pumice tuff, Scoria tuff, Lapilli tuff
Lithofacies (Basal): Tuffaceous sandstone

Thickness: 150 - 400 m
Upper limit: Kurotaki Unconformity (Urago Formation)
Lower limit: Transitional (Zushi Formation)

Ikego Formation
[ Upper ]
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Takatoriyama Volcaniclastics Member / Jimmuji Volcaniclastics and Mudstone Member
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[ Lower ]

Miura Group (Northern Miura peninsula)
[ Upper ]
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Ikego Formation
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Zushi Formation
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[ Lower ]

Mineoka Belt (Miura peninsula)
[ Upper ]
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Miura Group
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Hayama Group
?--?--?--?--?-
[ Lower ]

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

Distribution: Jinmuji, Zushi city, Kanagawa pref.; Enoshima island, Fujisawa city, Kanagawa pref.; Juniso, Kamakura city, Kanagawa pref.; Urago city - Hashirimizu - Cape Kannonzaki, Yokosuka city, Kanagawa pref.
Fossils: Sponnges (Makiyama chitanii), Foraminifera, Calcareous nannofossils

Takahashi et al. (2016) Jour. Geol. Soc. Japan, vol.122, no.8, pp.375-395, DOI
Eto et al. (1998) Geology of the Yokosuka District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 128p. (in Japanese with English abstract 3p.)