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Baiyunan Formation

Baiyunan Fm


Period: 
Silurian

Age Interval: 
Telychian of Silurian (S1), (55, 56)


Province: 
Sichuan

Type Locality and Naming

Chang Nongqing and Luo Zhengyuan created the Baiyunan System as a general name to represent all the Silurian strata in Huayingshan Mt. area in central Sichuan Province in 1933.

Synonym: (白云庵组), Baiyun'an Fm. The so-called “Hanjiadian Fm” at the Hongyan Coal Mine in Yuechi County of central Sichuan Province (Zhou Xiyun et al., 1984), 99 m in thickness, consists of varicolored mudstone and silty mudstone, comprising three layers of purple, and grey green as well, silty mudstone with a few limestone interbeds, should be renamed the Baiyunan Fm as the opinion of Rong Jiayu (1998, in Lin et al., 1998).


Lithology and Thickness

The Baiyunan Fm consists of green grey mudstone, purple mudstone and grey thick-bedded limestone. It is 584 m in thickness.


Lithology Pattern: 
Shallow-marine marl


Relationships and Distribution

Lower contact

It conformably overlying on the Xiaoheba Fm

Upper contact

is disconformably overlain by the Carboniferous System.

Regional extent

It is distributed in the Huayingshan Mt. area in central Sichuan Province.


GeoJSON

null

Fossils

Besides the anthozoan (Mesofavosites, Multisolenia, Halysites, etc.) and Stromatopora, it bears rich conodont of two assemblages: the lower assemblage is equivalent to the Spathognathodus parahassi--S. guizhouensis assemblage zone, and the upper assemblage is equivalent to the lower part of the Pterospathodus celloni assemblage zone.


Age 


Age Span: 

    Beginning stage: 
Telychian

    Fraction up in beginning stage: 
0.3

    Beginning date (Ma): 
436.89

    Ending stage: 
Telychian

    Fraction up in the ending stage: 
0.7

    Ending date (Ma):  
434.63

Depositional setting


Depositional pattern:  


Additional Information


Compiler:  

Wang Chuanshang and Wang Xiaofeng