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Joryu Formation

Joryu Fm


Period: 
Silurian

Age Interval: 
Pridolian (Pridoli), (19a)


Province: 
Kurosegawa Belt- Shikoku

Type Locality and Naming

Kurosegawa Belt-central Shikoku

Synonym:


Lithology and Thickness

Consists of conglomerate in the lower part and tuffaceous sandstone, acidic tuff and conglomerate in the upper part.

[Figure 1: Stratigraphy of the Paleozoic of the Kurosegawa Belt in the central part of Shikoku, Southwest Japan (after M. Ehiro et al., 2016)]


Lithology Pattern: 
Aus conglomerate


Relationships and Distribution

Lower contact

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

Upper contact

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

Regional extent

Kurosegawa Belt-central Shikoku


GeoJSON

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Fossils

The acidic tuff contains rich Pridolian radiolarians (Umeda 1998b, c).


Age 

Shown as Pridolian, hence placed Base of Pridoli

Age Span: 

    Beginning stage: 
Pridoli

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
422.73

    Ending stage: 
Pridoli

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
419.00

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.