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Baiyanggou Formation
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Baiyanggou Fm base reconstruction

Baiyanggou Fm

Period: 
Neoproterozoic

Age Interval: 
Nanhuan-Sinian (Cryogenian-Ediacaran), Z-Nh （13）


Province: 
Gansu

Type Locality and Naming

North Qilian (north-central Gansu). The Baiyanggou Fm was named by the No. 5 Team of the No. 2 Party of Regional Geologic Survey, Gansu Bureau of Geology in 1977. The typical section is situated in Dongshan of Baiyang valley, in Qiqing Township of Sunan County, Gansu Province.

Synonym: （白杨沟组）


Lithology and Thickness

The Baiyanggou Fm is glacial tillite boulderstone (diamictite), which is subdivided into two lithologic subformations. The Lower subformation is composed of grayish purple glacial tillite boulderstone (diamictite), variegated sheet pellodite and gray breccia cemented by calcareous or pelitic matter. The lower part of the Upper subformation is composed of gray purple, greenish gray sandy slate interbedded with brecciated limestone and its upper part, yellowish to gray purple thin-bedded pelitic limestone interbedded with clayey-calcareous sandy slate, bearing intercalations of thin-bedded fine sandstone, Fe ore and siltstone. The total thickness varies from 936 to 1270 m, of which the lower subformation is 364 to 935 m and the upper subformation is 140 to 335 m.


Lithology Pattern: 
Glacial till


Relationships and Distribution

Lower contact

The Baiyanggou Fm overlies unconformably the underlying Daliugou Gr of the Qingbaikouan (Tonian).

Upper contact

Its upper boundary is not preserved. Regional stratigraphic column indicates next higher unit is the Heicigou Gr (middle Ordovician).

Regional extent

North Qilian (north-central Gansu). It is exposed in Erdaogou, Baiyanggou to northwest of Xiaoliugou along the Beida River in Sunan County, Gansu Province.


GeoJSON

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Fossils


Age 

Nanhuan-Sinian (Cryogenian-Ediacaran) span on the schematic stratigraphic column, with lower glacial till assumed coeval with Sturtian glacial, then transitioning upward into non-glacial Ediacaran.

Age Span: 

    Beginning stage: 
Cryogenian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
720.00

    Ending stage: 
Ediacaran

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
538.80

Depositional setting

Most of researchers hold that the pebbles in the lower subformation bear obvious glacial striations and impressions and belong to the glacial deposit or a part is the glacio-fluvial deposit (by some researchers).


Depositional pattern:  


Additional Information


Compiler:  

Extracts from The Neoproterozoic Erathem (chapter in Stratigraphic Lexicon of China, draft of 2022) by Gao Linzhi, Ding Xiaozhong, Zhang Chuanheng, Zhang Heng.