Home Multi-Country Search About Admin Login
Cenozoic
Cretaceous
Jurassic
Triassic
Permian

Search by
Select Region(s) to search
Hold Ctrl (Windows/Linux) or Command (Mac) to select multiple
Koguro Formation

Koguro Fm


Period: 
Ordovician

Age Interval: 
Middle-Late Ordovician (Sandbian), (8b)


Province: 
South Kitakami Belt- Miyamori-Hayachine-Kamaishi district

Type Locality and Naming

Synonym:


Lithology and Thickness

It consists mainly of dolerite and basalt, with intercalated thin beds of tuffaceous sandstone and mudstone, and reddish hematite-quartz rock in the upper part.

[Figure 1: Stratigraphy of the Palaeozoic of the South Kitakatmi Belt, NE Japan (after M. Ehiro et al., 2016)]


Lithology Pattern: 
Granitic


Relationships and Distribution

Lower contact

Regionally, the schematic strat column indicates the next older unit as Kagura Unit Fm

Upper contact

Regionally, the schematic strat column indicates the next younger unit as Yakushigawa Fm

Regional extent


GeoJSON

null

Fossils


Age 

Shown as Middle-Late Ordovician, hence placed Base of Sandbian

Age Span: 

    Beginning stage: 
Sandbian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
458.18

    Ending stage: 
Katian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
445.21

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.