Hosoura Fm
Period:
Jurassic
Age Interval:
lowest Middle Jurassic (Sinemurian-Aalenian), (8e)
Province:
South Kitakami Belt-Western Sub-belt
Type Locality and Naming
Shizugawa (Shizukawa)-Hashiura Sub-belt; Shizugawa area
Synonym:
Lithology and Thickness
It consists of laminated and massive mudstone, and thin alternating beds of sandstone and mudstone
Lithology Pattern:
Clayey sandstone
Relationships and Distribution
Lower contact
The Hosoura Fm conformably overlies the Niranohama Fm
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Shizugawa Gr
Regional extent
Shizugawa (Shizukawa)-Hashiura Sub-belt; Shizugawa area
GeoJSON
null
Fossils
Many ammonoid species ranging from Sinemurian to Aalenian in age have been obtained from this formation (Sato 1962; Takahashi 1969; Sato & Westermann 1991).
Age
lowest Middle Jurassic (Sinemurian-Aalenian)
Age Span:
Beginning stage:
Sinemurian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
199.46
Ending stage:
Aalenian
Fraction up in the ending stage:
1.0
Ending date (Ma):
170.90
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.