Iwamura Group

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Iwamura Group (Saga, 1917) Uemura, 1961

Type locality: Gifu prefecture
Coherent formation
First Seto Inland Sea
Sedimentary basin in island arc
early Miocene, Burdigalian (17 - 16 Ma, FT; 18.3 - 17.0 Ma, Diatoms)

Sedimentary facies: Marine, Freshwater
Lithofacies: Siltstone, Sandstone
Lithofacies (Minor): Conglomerate, Tuff

Upper limit: Unconformity (Toki Formation, Higashibara Formation, Akechi Formation)
Lower limit: Unconformity (Ryoke Metamorphic Rocks, Younger Ryoke Granitoids)

Iwamura Group
[ Upper ]
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Toyama Formation
~~~~~~~-------
Agi Formation
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[ Lower ]

First Setouchi Supergroup (Iwamura basin, Gifu pref.)
[ Upper ]
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Iwamura Group
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[ Lower ]

[ Upper ]
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Second Setouchi Supergroup
?--?--?--?--?-
First Setouchi Supergroup
~~~~~~~~~~~~~~
[ Lower ]

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

Distribution: Agi, Nakatsugawa city, Gifu pref.; Iwamura town - Yamaoka town, Ena city, Gifu pref.
Fossils: Bivalves
Fossils (Iwamura flora): Acer ezoanum, Alangium aequalifolium, Comptonia naumanni, Quercus miovariablis, Quercus pragilva, Ulmus carpinoides, Zelkova ungeri

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.)
Sasao et al. (2011) Jour. Geol. Soc. Japan, vol.117, no.8, pp.476-481 DOI