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Yanshan Formation
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Yanshan Fm base reconstruction

Yanshan Fm

Period: 
Neoproterozoic

Age Interval: 
mid-Early Qingbaikouan (early Tonian) , Qb (61)


Province: 
Zhejiang

Type Locality and Naming

North Zhejiang. The Yanshan Fm was named by the Party of Regional Geological Survey, Zhejiang Bureau of Geology and Mineral Re-sources in 1990. The naming section is at Yanshan Mountain in Zhangcun Village, Fuyang City, Zhejiang Province.

Synonym: （岩山组）


Lithology and Thickness

The Yanshan Fm is dominated by a interbedding of grey-green schistose tuffite, tuffaceous siltstone, tuffaceous sandstone and tuff breccia. Lower part is dominated by tuffaceous sandstone, sandwiched with tuffaceous sandy conglomerate and brecciated tuffite. Upward, the tuffite increases in which involution bedding, detachment structures and scour surfaces are seen locally. The formation is over 474 m thick.


Lithology Pattern: 
Volcanic ash


Relationships and Distribution

Lower contact

It is in conformable contact both with the underlying Beiwu Fm

Upper contact

It is in conformable contact with the overlying Zhangcun Fm

Regional extent

North Zhejiang. It widespread mainly around Shuangxiwu between Fuyang County and Xiaoshan County, Zhejiang Province.


GeoJSON

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Fossils


Age 

The age of the Yanshan Fm is between that of the Beiwu Fm with its date of 901.6±5.5 Ma and of the Zhangcun Fm with its date of 899±8 Ma. (Gao Linzh et al., 2014). mid-Early Qingbaikouan (early Tonian) on schematic stratigraphic section.

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: 
0.3

    Ending date (Ma):  
916.00

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.