Kogoshio Fm
Period:
Jurassic
Age Interval:
Middle Jurassic (Callovian), (8h)
Province:
South Kitakami Belt-Central Sub-belt
Type Locality and Naming
the Karakuwa-Oshika Sub-belt
Synonym:
Lithology and Thickness
It is rich in sandstone and mudstone with rare conglomerate. The sandstone is arkosic, and those in the lower part are thick, coarse-grained and quartzose.
Lithology Pattern:
Sandstone
Relationships and Distribution
Lower contact
Regionally, the schematic strat column indicates the next older unit as Mone Fm
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Isokusa Fm
Regional extent
GeoJSON
null
Fossils
This formation has yielded shallow-marine bivalves (Hayami 1961a).
Age
Shown as Middle Triassic-lowermost Cretaceous hence placed Base of Callovian
Age Span:
Beginning stage:
Callovian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
165.29
Ending stage:
Berriasian
Fraction up in the ending stage:
0.5
Ending date (Ma):
140.40
Depositional setting
The middle part is thought to be an alluvial deposit (Takizawa 1985).
Depositional pattern:
Additional Information
Compiler:
Moreno, T., WALLIS, S., Kojima, T. & Gibbons, W. (Eds) 2016. The Geology of Japan. Geological Society. London. 1-24.