Kosaba Formation

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Kosaba Formation

Coherent formation
Middle Jurassic, Early - Middle Bajocian (Ammonoids)

Sedimentary facies: Marine
Lithofacies: Sandstone
Lithofacies (Minor): Slate

Thickness: 3 - 300 m
Upper limit: Conformity (Tsunagizaka Formation)
Lower limit: Unconformity (Inai Group)

Karakuwa Group
[ Upper ]
~~~~~~~~~~~~~~
Tsunagizaka Formation
--------------
Kosaba Formation
~~~~~~~~~~~~~~
[ Lower ]

Karakuwa-Oshika Subbelt
[ Upper ]
?--?--?--?--?-
Shishiori Group
~~~~~~~~~~~~~~
Karakuwa Group
~~~~~~~~~~~~~~
[ Lower ]

South Kitakami Belt (after Permian)
[ West ]
::::::::::::::
Shizukawa-Hashiura Subbelt
::::::::::::::
Karakuwa-Oshika Subbelt
::::::::::::::
Ofunato Subbelt
::::::::::::::
[ East ]

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

Distribution: Kesennuma city, Miyagi pref.
Fossils: Belemnites sp.
Fossils (Ammonoids): Pelekodites (Spatulites) spatians, Sonninia cf. corrugata, Stephanoceras cf. plicatissimum
Fossils (Shellfishes): Astarte? sp., Inoceramus spp., Leda? sp., Lima, Macrodon sp., Nucula? sp., Trigonia (Lyrodon) sumiyagura, Torigonia (Vaugonia) yokoyamai, Vaugonia (Hijitrigonia) geniculata

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.)