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Jiudaoguai Formation
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Jiudaoguai Fm base reconstruction

Jiudaoguai Fm

Period: 
Neoproterozoic

Age Interval: 
Early Sinian (early Ediacaran), (41-a)


Province: 
Shaanxi

Type Locality and Naming

West Shaanxi. The Jiudaoguai Fm was named by the Qinling Team of Regional Geological Survey of Shaanxi Geology Bureau in 1967. The typical section is situated in Jiudaoguai in Lueyang County, and the reference section is in Chadian of Miaxian County, Shaanxi Province.

Synonym: （九道拐组）


Lithology and Thickness

Lower part of the Jiudaoguai Fm is composed of gray to dark gray carbonaceous argillite, marl, siliceous mudstone, phyllite and siliceous micritic dolomite intercalated with siliceous bandings and silty slate. Middle part is gray, greenish gray and yellowish-brown leopard pelitic limestone intercalated with gray banded pelitic slate. Upper part consists of thick-to thin-bedded siliceous and pelitic dolomite. It is more than 367 m thick. Around Chadian and Xuanwoliang, the middle part has stromatolites and the basal part has 2 to 5 m thick siltstone. In Wangtianping and Dongzigou of south Mianxian, the middle to lower part is limestone, mudstone intercalated with carbonaceous slate, with a thickness of 1250 to 1550 m.


Lithology Pattern: 
Clayey limestone


Relationships and Distribution

Lower contact

The Jiudaoguai Fm rests conformably on the underlying Duantouya Fm

Upper contact

It conformably underlies the Wangtianping Fm

Regional extent

West Shaanxi. It is distributed in Hejiaya, Duantouya of Lueyang County, in Chadian, Hongyangou, Huiduishan, Jigongshan of Mianxian County and in Xuehuataiping, Dongfanggou, Shapogou of Ningqiang County.


GeoJSON

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Fossils

This formation yields stromatolites: Colonnella f., Conophyton garganicum, Kussiella f. etc., and Microplants: Polyporata microporosa etc.


Age 

Early Sinian (early Ediacaran) on schematic stratigraphic column

Age Span: 

    Beginning stage: 
Ediacaran

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
635.00

    Ending stage: 
Ediacaran

    Fraction up in the ending stage: 
0.5

    Ending date (Ma):  
586.90

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.