Isokusa Formation

Type locality: Isokusa, Oshima island, Kesennuma city, Miyagi prefecture
Coherent formation
Early Cretaceous, Berriasian - Valanginian
Correlation: Koyamada Formation

Sedimentary facies: Marine

Upper limit: Unknown
Lower limit: Unknown

Kesennuma, Miyagi pref.
[ Upper ]
?--?--?--?--?-
Yokonuma Formation
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Kanaigaura Formation
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Niitsuki Formation
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Nagasaki Formation
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Isokusa Formation
?--?--?--?--?-
[ Lower ]

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

Distribution: Isokusa - Nagasaki, Oshima island, Kesennuma city, Miyagi pref.
Fossils: Belemnites (Hibolithes sp.), Brown algae (Alaria cf. myurus)
Fossils (Ammonoids): Berriasella sp., Kilianella sp., Olcostephanus sp., Thurmanniceras isokusensis (Perisphictes (Discosphinctes) isokusense��)
Fossils (Shellfishes): Astarte cf. elegans, Astarte cf. hermanni, Myophorella (Promyophorella) obsoleta, Myophorella (Promyophorella) orientalis, Spondylus? sp., Trigonia cf. formosa

Sano et al. (2015) Jour. Geol. Soc. Japan, vol.121, no.2, pp.71-79 DOI
Kambe and Shimazu (1961) Kesennuma, Explanatory Text of the Geological Map of Japan, Scale 1:50,000, Geological Survey of Japan, 73p. (in Japanese with English abstract 16p.)