Toyosaka Member

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Toyosaka Member (Ota and Katada, 1955)

Invalid synonym: Toyosaka Andesites, Toyosaka Formation

Type locality: Kirimiya mountain road, Matsushiro town, Nagano city, Nagano prefecture
Volcanic rocks
middle Miocene
Contemporaneous heterotopic facies: Mori Member

Lithofacies: Tuff, Tuff breccia, Volcanic breccia, Shale
Lithofacies (Minor): Interbedded shale and sandstone, Interbedded shale and tuffaceous sandstone

Thickness: ca. 600 m
Upper limit: Conformity (Bessho Formation)
Lower limit: Conformity (Yokoo Member)

Uchimura Formation (Northern part)
[ Upper ]
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Mori Member / Toyosaka Member
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Yokoo Member => Yokoo Formation
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Taroyama Member => Taroyama Formation
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Omineyama Member => Omineyama Formation
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[ Lower ]

Chushin Group
[ Upper ]
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Bessho Formation
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Uchimura Formation
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Moriya Formation
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[ Lower ]

northern Nagano pref.
[ Upper ]
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Hokushin Group
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Chushin Group
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[ Lower ]

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

Distribution: Kirimiya mountain road - Toyosaka - Akashiba - Inaba, Matsushiro town, Nagano city, Nagano pref.
Fossils: Shellfishes?, Foraminifera?

Kato and Akahane (1986) Geology of the Nagano District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 120p. (in Japanese with English abstract 5p.)
Ota and Katada (1955) Suzaka, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 54p. (in Japanese with English abstract 6p.)