Byobuiwa Tuff Member

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Byobuiwa Tuff Member (Matsuda and Mizuno, 1955) Ozaki and Sugiyama, 2018

Type locality: Deguchi - Takenoshima, Tokiwa, Minobu city, Minamikoma county, Yamanashi prefecture
Volcanic rocks
middle Miocene

Sedimentary facies: Marine
Sedimentary facies: Volcanic products, Deep sea sediments
Depth of water: lower Bathyal
Lithofacies: Pyroclastic flow deposit
Lithofacies: Dacite pumice tuff, Tuffaceous sandstone
Lithofacies (Minor): Tuffaceous conglomerate, Mudstone

Thickness: ca. 220 - 680 m
Upper limit: Conformity (Shimobe Formation)
Lower limit: Conformity (Deguchi Sandstone and Mudstone Member)

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: Tokiwa - Byobuiwa - Daigoyama - Isshiki - Miyaki - Shimotanbara - Iitomi - Kiriishi - Teuchizawa - Amegochi river, 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.)