Zyumonzi Formation

Zyumonzi Formation (Chinzei, 1958) Tuzino et al., 2018

Invalid synonym: Lower Tomesaki Formation, Zyumonzi Sandstone Member, Kamayashiki Formation

Type locality: Jumonji river, Jumonji - Kamayashiki - Kamitomai, Ninohe city, Iwate prefecture
Coherent formation
middle Miocene (15 - 12 Ma, Microfossils)

Sedimentary facies: Shallow marine
Climate: Tropical - Subtropical (Foraminifera), Warm temperate (Plants)
Lithofacies (Main part): Tuffaceous sandstone
Lithofacies (Minor): Siltstone, Glauconite sandstone
Sedimentary structures: Cross stratification

Thickness: 100 - 200 m
Upper limit: Transitional (Yanagisawa Formation), Conformity (Kamimetoki Sandstone Member), Unconformity (Toya Formation, Nanashigure Volcanic Fan Deposit, Asanai Terrace Deposit)
Lower limit: Unconformity (Suenomatuyama Formation)

Zyumonzi Formation
[ Upper ]
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Shimotomai Volcaniclastic Rock Member
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Metoki Coquina Conglomerate Member
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Hinosawa Conglomerate Member
~~~~~~~~~~~~~~
[ Lower ]

Sannohe Group
[ Upper ]
~~~~~~~~~~~~~~
Kubo Formation
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Shitazaki Formation
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Yanagisawa Formation
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Zyumonzi Formation
~~~~~~~~~~~~~~
[ Lower ]

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

Distribution: Kintaichi - Jumonji - Kamayashiki - Shimotomai - Ainoyama - Appi, Ninohe city, Iwate pref.; Tsukidate - Otomo, Ichinohe city, Ninohe county, Iwate pref.; Asakusazawa, Karumai city, Kunohe county, Iwate pref.; Miyazawa, Sannohe city, Sannohe county, Aomori pref.; Nagasawa, Toya, Nanbu city, Sannohe county, Aomori pref.
Fossils: Shellfishes, Pipe rocks
Fossils (Plants): Buxus protojaponica, Cinnamomum cf. miocenum, Fagus palaeocrenata, Fagus Protojaponica, Lindera sp.

Tuzino et al. (2018) Geology of the Ichinohe District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 161p. (in Japanese with English abstract 4p.)