Kosaba Fm
Period:
Triassic
Age Interval:
Middle Triassic (Aalenian), (8h)
Province:
South Kitakami Belt-Central Sub-belt
Type Locality and Naming
the Karakuwa-Oshika Sub-belt
Synonym:
Lithology and Thickness
It consists of basal conglomeratic sandstone then sandstone intercalated with mudstone.
Lithology Pattern:
Coarse-grained sandstone
Relationships and Distribution
Lower contact
It rests unconformably on the lsatomae Fm
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Tsunakizaka Fm
Regional extent
GeoJSON
null
Fossils
Sandstone intercalated with mudstone yielded Bajocian molluscs (Hayami 1961a).
Age
Shown as Middle Triassic-lowermost Cretaceous hence placed Base of Aalenian
Age Span:
Beginning stage:
Aalenian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
174.70
Ending stage:
Aalenian
Fraction up in the ending stage:
0.5
Ending date (Ma):
172.80
Depositional setting
Depositional pattern:
Additional Information
Compiler:
Moreno, T., WALLIS, S., Kojima, T. & Gibbons, W. (Eds) 2016. The Geology of Japan. Geological Society. London. 1-24.