Tomiyama Formation

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Tomiyama Formation Suzuki et al., 1979

Type locality: Tomiyama, Minamiboso city, Chiba prefecture
Accretionary complex
early - middle Miocene
Correlation: Fukawa Formation

Sedimentary facies: Marine
Lithofacies: Sandstone, Interbedded sandstone and mudstone
Lithofacies (Minor): Mudstone

Thickness: ca. 300 - 1,400 m
Upper limit: Bottom of the horizon which does not include sandstone beds of a few dozen cm thick
Upper limit: Conformity (Ezuki Formation)
Lower limit: Bottom of the sandstone intercalating horizon
Lower limit: Conformity (Aokiyama Formation)

Hota Group (Western part)
[ Upper ]
~~~~~~~~~~~~~~
Ezuki Formation
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Tomiyama Formation
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Aokiyama Formation
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Masuma Formation
::::::::::::::
[ Lower ]

Hota Group (Eastern part)
[ Upper ]
~~~~~~~~~~~~~~
Emi Formation
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Nabuto Formation
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Takazuru Formation
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Furubo Formation
~~~~~~~~~~~~~~
[ Lower ]

Mineoka Belt (Boso peninsula)
[ Upper ]
~~~~~~~~~~~~~~
Awa Group / Minamiboso Group
~~~~~~~~~~~~~~
Hota Group
::::::::::::::
Mineoka Group
?--?--?--?--?-
[ Lower ]

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

Distribution: Tomiyama - Mount Iyogatake - Iinozaka, Minamiboso city, Chiba pref.; Tako - Sunada - Mount Tsunobeyama - Nakasakuma- Ryushima, Kyonan city, Awa county, Chiba pref.
Fossils (Silicoflagellates): Corbisema triacantha, Mesocena apiculata

Takahashi et al. (2016) Jour. Geol. Soc. Japan, vol.122, no.8, pp.375-395, DOI
Suzuki et al. (1990) Geology of the Nago District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 48p. (in Japanese with English abstract 3p.)