Shikiya Mudstone

Type locality: Kumanogawa river, Shingu city, Wakayama prefecture
Coherent formation
Miocene
Intruded by: Sandstone dike

Sedimentary facies: Marine
Lithofacies: Mudstone, Interbedded sandstone and mudstone
Lithofacies (Minor): Conglomerate
Lithofacies (Basal Minor): Calcareous sandstone

Thickness: 1,000 - 1,300 m
Upper limit: Conformity (Mitsuno Formation)
Lower limit: Conformity (Shimosato Sandstone and Mudstone)

Koguchi Formation
[ Upper ]
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Shikiya Mudstone
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Shimosato Sandstone and Mudstone
~~~~~~~~~~~~~~
[ Lower ]

Kumano Group
[ Upper ]
~~~~~~~~~~~~~~
Mitsuno Formation
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Koguchi Formation
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Onuma Formation
~~~~~~~~~~~~~~
[ Lower ]

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

Distribution: Kumanogawa river, Shingu city, Wakayama pref.; Konogawa - Ikushi - Kujinokawa - Cape Shionomisaki - Oshima island - Hakoshima island - Kuroshima island, Kushimoto city, Higashimuro county, Wakayama pref.; Narimigawa river - Okuban - Itamidaira, Kozagawa city, Higashimuro county, Wakayama pref.
Fossils: Corals, Brachiopods (Terebratalia? sp.), Foraminifera (Cyclammina sp.), Bryozoans
Fossils (Shellfishes): Acila submirabilis, Aloidis cf. succincta, Conus tokunagai, Crassatellites cf. namus, Pecten sp., Placopecten? sp., Portlandia murayamai, Propeamussium tateiwai, Solen sp., Tapes sp., Venericardia sp., Vicarya? sp.

Hirokawa and Mizuno (1965) Kushimoto, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 25p. (in Japanese with English abstract 3p.)
Mizuno (1957) Nachi, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 37p. (in Japanese with English abstract 3p.)