Mashizume Formation

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Mashizume Formation Todo Collaborative Research Group, 1982

Invalid synonym: Yamagami Formation, Tazawa Formation

Type locality: Mashizume, Sue town, Mizunami city, Gifu prefecture
Coherent formation
Fluvio-lacustrine basin including Lake Tokai
late Miocene - Pliocene
Correlation: Toki Sand and Gravel Formation, Byobuzan Formation, Namimatsu Formation, Fujioka Formation

Sedimentary facies: Braided river
Lithofacies: Gravels
Lithofacies (Minor): Sands, Silt, Clay
Sedimentary structures: Channel structure, Trough cross-stratification, Parallel stratification, Imbricate structure

Thickness: ca. 80 m
Lower limit: Unconformity (Higashibara Formation, Maki Siltstone Member, Kubohara Sandstone Facies, Akechi Formation, Ryoke Metamorphic Rocks, Younger Ryoke Granitoids)

Tokai Group (Mizunami, Gifu pref.)
[ Upper ]
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Mashizume Formation
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Higashibara Formation
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[ Lower ]

Second Setouchi Supergroup (Mie pref. - Aichi pref.)
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Tokai Group
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[ Upper ]
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Second Setouchi Supergroup
?--?--?--?--?-
First Setouchi Supergroup
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[ Lower ]

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

Distribution: Hara, Yamaoka town, Ena city, Gifu pref.; Oizumi - Arai - Okute, Akechi town, Ena city, Gifu pref.; Mashizume - Tenguiwa, Sue town, Mizunami city, Gifu pref.; Okusa, Toki city, Gifu pref.; Ogazore town - Komuratoge pass, Toyota city, Aichi pref.

Yamasaki et al. (2020) Geology of the Akechi District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 120p. (in Japanese with English abstract 5p.)