Yokonuma Fm
Period:
Cretaceous
Age Interval:
Early Cretaceous (Hauterivian), (8h)
Province:
South Kitakami Belt-Central Sub-belt
Type Locality and Naming
the Karakuwa-Oshika Sub-belt
Synonym:
Lithology and Thickness
It is composed of sandstone, mudstone and alternating beds of sandstone and mudstone with rare limestone and tuffaceous sandstone
Lithology Pattern:
Sandy_claystone
Relationships and Distribution
Lower contact
Regionally, the schematic strat column indicates the next older unit as Karakuwa Gr
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Kanaegaura Fm
Regional extent
GeoJSON
null
Fossils
Since it has yielded the ammonoid Crioceratites (C.) ishiwarai (Yabe & Shimizu
1925) along with corals and bivalves, it is dated as Hauterivian-Barremian (Obata1988)
Age
It is dated as Hauterivian-Barremian (Obata1988)
Age Span:
Beginning stage:
Hauterivian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
132.60
Ending stage:
Barremian
Fraction up in the ending stage:
1.0
Ending date (Ma):
121.40
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.