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Yumen Formation
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Yumen Fm base reconstruction

Yumen Fm

Period: 
Neoproterozoic

Age Interval: 
Qb (44?)


Province: 

Type Locality and Naming

Southernmost Sichuan. The Yumen Fm was named by the No. 106 Party of Regional Geological Survey, Sichuan Bureau of Geology in 1974. The naming section is in Xinjietian-Xinping, Yanbian County, Sichuan Province. Lower-middle formation in the Yanbian Gr.

Synonym: （渔门组）


Lithology and Thickness

The Yumen Fm is composed of rhythmic interbedding of thin-bedded low-grade metamorphosed clastic rock. Lower part is mainly composed of blue-grey to dark gray carbonaceous slate, sericite slate, siliceous slate intercalated with crystalline limestone lenses and metamorphosed marl, as well as sandy limestone. Middle and Upper parts are interbedding of metamorphosed tuffaceous slate, sandy slate and slate. The formation is 1700 m thick.


Lithology Pattern: 
Claystone


Relationships and Distribution

Lower contact

It is in conformable or disconformable contact with underlying Huangtian Fm

Upper contact

The top is in conformable contact with overlying Xiaoping Fm

Regional extent

Southernmost Sichuan. The formation is exposed in Yumen and Huimin zone, Yanbian County, Sichuan Province.


GeoJSON

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Fossils


Age 

early Qingbaikouan (early Tonian)

Age Span: 

    Beginning stage: 
Tonian

    Fraction up in beginning stage: 
0.2

    Beginning date (Ma): 
944.00

    Ending stage: 
Tonian

    Fraction up in the ending stage: 
0.4

    Ending date (Ma):  
888.00

Depositional setting


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.