Isatomae Fm
Period:
Triassic
Age Interval:
Early-Middle Triassic (Ladinian), (8e, 8f, 8g, 8h)
Province:
South Kitakami Belt-Central Sub-belt, South Kitakami Belt-Western Sub-belt
Type Locality and Naming
the Karakuwa-Oshika Sub-belt, the Shizugawa (Shizukawa)-Hashiura Sub-belt; Mizunuma area, the Shizugawa (Shizukawa)-Hashiura Sub-belt; Hashiura area, the Shizugawa (Shizukawa)-Hashiura Sub-belt; Shizugawa area
Synonym:
Lithology and Thickness
It consists of laminated sandy mudstone to muddy sandstone, intercalated with thick sandstone beds.
Lithology Pattern:
Sandy_claystone
Relationships and Distribution
Lower contact
Regionally, the schematic strat column indicates the next older unit as Fukkoshi Fm
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Inai Gr
Regional extent
GeoJSON
null
Fossils
It yield Anisian ammonoids (Mojsisovics 1888; Diener 1916; Shimizu 1930; Onuki & Bando 1959; Bando1964), with the work of Mojsisovics (1888) providing the first description of ammonoid fossils from Japan
Age
Shown as Lower-Middle Triassic, hence placed Base of Ladinian
Age Span:
Beginning stage:
Ladinian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
241.46
Ending stage:
Pliensbachian
Fraction up in the ending stage:
1.0
Ending date (Ma):
184.20
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.