Tokiwa Formation

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Tokiwa Formation (Matsuda, 1958) Ozaki and Sugiyama, 2018

Invalid synonym: Godaigo Formation

Type locality: Ichinose - Tokiwa - Isshiki - Miyaki, Minobu city, Minamikoma county, Yamanashi prefecture
Volcanic rocks
middle Miocene (ca. 14 - 11.6 Ma)
Correlation: Funayama Mudstone Member

Sedimentary facies: Marine
Sedimentary facies: Volcanic products, Deep sea sediments
Sedimentary facies: Volcanic activities at spreading back-arc
Depth of water: Abbyssal
Lithofacies: Back-arc basin basalt
Lithofacies (Dacite): Rift system ryolite
Lithofacies (Minor): Dacite pyroclastic flow deposit, Basalt - andesite lava, Volcaniclastic rocks

Thickness: ca. 1,100 - 2,000 m
Lower limit: Conformity (Furusekigawa Formation)

Tokiwa Formation
[ Upper ]
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Byobuiwa Tuff Member
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Deguchi Sandstone and Mudstone Member
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Tsukimibashi Volcaniclastic Member
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Kamiisshiki Volcanic Breccia Member
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Wadaira Tuff Member
'''''''/,,,,,,
Kanzaka Mudstone Member
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[ Lower ]

Nishiyatsushiro Group (eastern Minobu, Yamanashi pref.)
[ Upper ]
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Tokiwa Formation
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Furusekigawa Formation
?--?--?--?--?-
[ Lower ]

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

Distribution: Ichinose - Tokiwa - Isshiki - Miyaki, Minobu city, Minamikoma county, Yamanashi pref.

Ozaki and Sugiyama (2018) Geology of the Minobu District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 169p. (in Japanese with English abstract 7p.)