Home Multi-Country Search About Admin Login
Cenozoic
Cretaceous
Jurassic
Triassic
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
Neoproterozoic
Mesoproterozoic

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

Anzigou Fm

Period: 
Silurian

Age Interval: 
Rhuddanian of Silurian (S1)


Province: 
Gansu

Type Locality and Naming

It was named by the Gansu Party of Regional Geological Survey in 1975 and published by Zai Yupei in 1977. The type section is at Anzigou in Diebu County, Gansu Province.

Synonym: (安子沟组)

Reference Section:

The reference section is at Baiyigou in Ruoergai County, Sichuan Province.


Lithology and Thickness

The formation, 1490 m in thickness, can be subdivided into 3 parts. Lower part consists of light grey tuff intercalated with black carbonaceous slate; Middle and Upper parts are composed of black carbonaceous slate, phyllite, carbonaceous siliceous slate and chert.


Lithology Pattern: 
Claystone


Relationships and Distribution

Lower contact

It contacts conformably with the underlying Ordovician rocks.

Upper contact

It contacts conformably with the overlying Gezi Fm

Regional extent

The lithology is rather steady, but the thickness varies considerably, 730 m thick at Baiyigou, Ruoergai County, 1318 m thick at Tiebuamitang, and 670-750 m at Yangchanggou of Jiangzhang and at Talsai of Zhangwa Town.


GeoJSON

null

Fossils

It bears graptolites of the Akidograptus zone, the Pristiograptus leei zone, etc.


Age 

Beginning put as as base-Silurian for graphics; but may begin within Late Ordovician

Age Span: 

    Beginning stage: 
Rhuddanian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
443.07

    Ending stage: 
Aeronian

    Fraction up in the ending stage: 
0.0

    Ending date (Ma):  
440.49

Depositional setting


Depositional pattern:  


Additional Information


Compiler:  

Wang Chuanshang and Wang Xiaofeng