Oyama Subgroup

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Oyama Subgroup

Volcanic rocks
Oceanic arc of Paleo-Izu-Bonin arc
Mountain flank deposits of submarine volcanos and volcanic islands on Tanzawa mass
early - middle Miocene (16.0 - 13.0 Ma)

Sedimentary facies: Marine
Metamorphic facies: Prehnite-Pumpellyite
Lithofacies: Subaqueous volcaniclastics, Subaqueous lavas

Thickness: 1,850 - 3,900 m
Upper limit: Conformity
Lower limit: Conformity

Oyama Subgroup
[ Upper ]
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Karasawagawa Formation
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Hondanigawa Formation
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[ Lower ]

Tanzawa Group
[ Upper ]
~~~~~~~-------
Susugaya Subgroup
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Oyama Subgroup
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Togatake Subgroup
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[ Lower ]

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

Distribution: Tanzawa mountains, Kanagawa pref.
Fossils: Corals, Nautilus, Calcareous algae, Foraminifera

Ishikawa et al. (2016) Jour. Geol. Soc. Japan, vol.122, no.7, pp.291-304, DOI
Ueki et al. (2013) Geology of the Hachioji District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 137p. (in Japanese with English abstract 6p.)
Oka et al. (1979) Geology of the Fujisawa District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 111p. (in Japanese with English abstract 5p.)