Yoshiwa Group

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Yoshiwa Group

Paleozoic volcanic island arc in the ocean (Yakuno paleo-island arc)
Coherent formation
Deposition (Siliceous shale): middle - late Permian (Radiolrians)
Deposition (Mudstone): middle - late Permian (Radiolrians)
Correlation: Maizuru Group

Sedimentary facies: Marine
Lithofacies (Upper): Mudstone, Sandstone
Lithofacies (Lower): Mafic volcanic rocks, Gabbro
Lithofacies (Lower, Minor): Ultramafic rocks

Central zone (Hiroshima)
[ Upper ]
?--?--?--?--?-
Karita Formation
?--?--?--?--?-
Hachimandai Formation
?--?--?--?--?-
Yoshiwa Group
?--?--?--?--?-
[ Lower ]

Maizuru Belt
[ North ]
/--/--/--/--/-
North zone
/--/--/--/--/-
Central zone
/--/--/--/--/-
South zone
/--/--/--/--/-
[ South ]

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

Distribution: Yoshiwa, Hatsukaichi city, Hiroshima pref.
Fossils (Radiolarians):

Kimura et al. (2019) Jour. Geol. Soc. Japan, vol.125, no.2, pp.153-165 DOI
Takahashi (1991) Geology of the Hiroshima District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 41p. (in Japanese with English abstract 3p.)