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Qiujidonggou Gr
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Qiujidonggou Gr base reconstruction

Qiujidonggou Gr

Period: 
Neoproterozoic

Age Interval: 
Qingbaikouan (Tonian), Qb (33)


Province: 
Qinghai

Type Locality and Naming

Southwest Qinghai, south margin Qaidam Basin. The Qiujidonggou Gr was named by the Qinghai Institute of Geology and Mineral Resources in 1984 and formally quoted in 1990 (on the Regional Geology of Qinghai Province). The typical section is situated in Qiujidonggou in Dulan County, Qinghai Province.

Synonym: （丘吉东沟群）


Lithology and Thickness

The Qiujidonggou Gr is dominated by gray to dark gray fine-grained clastic rock, including gray phyllitic silty claystone, siltstone, siliceous and carbonaceous slate, chert intercalated with fine quartzose sandstone, polymictic sandstone, coarse sandstone-psepholite, siliceous dolomite and dolomite. Without the uppermost sequence, the Qiujidonggou Group outcrops more than 1500 m thick.


Lithology Pattern: 
Sandy claystone


Relationships and Distribution

Lower contact

It rests disconformably on the underlying Binggou Gr (Mesoproterozoic)

Upper contact

Regionally, next younger unit is Upper Ordovician.

Regional extent

Southwest Qinghai, south margin of Qaidam Basin (Qimantag and Burhanbuda Mtns). The Qiujidonggou Group is distributed in Bingnao area in Dulan County, Qinghai Province.


GeoJSON

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Fossils

The dolomite yields stromatolite Conophyton qiujidonggouense and the fineclastic rock yields microplants: Trematosphaeridium sp., Laminarites sp. etc.


Age 

The silty argillite from the middle part was dated 676± 65 Ma by Rb-Sr whole rock method (metamorphism age). Span (dotted) of Qingbaikouan (Tonian) on schematic stratigraphic column

Age Span: 

    Beginning stage: 
Tonian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
1,000.00

    Ending stage: 
Tonian

    Fraction up in the ending stage: 
0.8

    Ending date (Ma):  
776.00

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.