Aratozaki Fm
Period:
Jurassic
Age Interval:
Middle Jurassic (Bajocian), (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 mainly of arkose in association with conglomerate and alternating beds of sandstone and mudstone
Lithology Pattern:
Sandstone
Relationships and Distribution
Lower contact
The Aratozaki Fm and its equivalents rest unconformably on the Hosoura Fm or the Isatomae Fm
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Arato Fm
Regional extent
Shizugawa (Shizukawa)-Hashiura Sub-belt; Shizugawa area. Coeval with Nakahara Fm; Kojima Fm
GeoJSON
null
Fossils
It yields bivalve fossils such as Inoceramus, Trigonia and Vaugonia (Hayami 1961b).
Age
Middle Jurassic (Bajocian)
Age Span:
Beginning stage:
Bajocian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
170.90
Ending stage:
Bajocian
Fraction up in the ending stage:
0.5
Ending date (Ma):
169.54
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.