Yakushigawa Fm
Period:
Ordovician
Age Interval:
Late Ordovician (Hirnantian), (8b)
Province:
South Kitakami Belt- Miyamori-Hayachine-Kamaishi district
Type Locality and Naming
Synonym:
Lithology and Thickness
It consists of mudstone and sandstone in association with tuff and basalt in the lower part.
[Figure 1: Stratigraphy of the Palaeozoic of the South Kitakatmi Belt, NE Japan (after M. Ehiro et al., 2016)]
Lithology Pattern:
Clayey sandstone
Relationships and Distribution
Lower contact
The Yakushigawa Fm conformably overlies the Koguro Fm
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Nameirizawa Fm
GeoJSON
null
Fossils
Age
Shown as Late Ordovician, hence placed Base of Hirnantian
Age Span:
Beginning stage:
Hirnantian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
445.21
Ending stage:
Hirnantian
Fraction up in the ending stage:
1.0
Ending date (Ma):
443.07
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.