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Xiuning Formation
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Xiuning Fm base reconstruction

Xiuning Fm

Period: 
Neoproterozoic

Age Interval: 
Earliest Nanhuan (latest Tonian), Nh (60)


Province: 
Anhui

Type Locality and Naming

Southernmost Anhui. Li Yuyao (Y. Y. Lee) and Xu Be (S. C. Hsu) firstly named Xiuning sandstone in 1935, and the Xiuning Formation was named by the No. 317 Party of Anhui Bureau of Geology in 1965. The naming section is located at Lantian, Xiuning County, Anhui Province.

Synonym: （休宁组）


Lithology and Thickness

The Xiuning Fm is subdivided into three parts. The lower part is gray green, purple red medium-thick fine-grained sandstone and siltstone, basal conglomerate and pebbly feldspar quartz sandstone with cross-bedded, ripple-bedded and horizontal-bedded, which belongs to sediments of beach facies. The middle part is gray green, gray white and gray purple fine-grained sandstone, muddy siltstone and mudstone with siltstone. Fine horizontal beddings are well developed, with minor cross-bedded and deformation-bedded in sandstone showing the sediments of transitional zone. The upper part is gray green, blue green and purple red rhythmites of fine-grained sandstone, siltstone and silty mudstone with glauconite and pyrite. Channels, ripples and involution bedding are well developed in the upper part. It is 1398 m thick in total.


Lithology Pattern: 
Fine-grained sandstone


Relationships and Distribution

Lower contact

Conformable on the Likou Gr (Puling Fm), or unconformable on the underlying Shangxi Gr

Upper contact

It is disconformable below the overlying Nantuo Fm (tillite). However, schematic stratigraphic column (60) shows the overlying unit as the Gucheng Fm tillite.

Regional extent

Southernmost Anhui.


GeoJSON

{"type":"Feature","geometry":{"type":"MultiPolygon","coordinates":[[[[117.66,30.64],[117.93,30.65],[118.21,30.45],[118.63,30.11],[118.58,30],[118.39,29.86],[118.12,29.69],[117.95,29.6],[117.72,29.42],[117.29,29.17],[116.95,28.93],[116.76,28.92],[116.52,28.95],[116.33,29.03],[116.29,29.31],[116.38,29.49],[116.65,29.69],[116.87,29.93],[117.12,30.16],[117.41,30.44],[117.66,30.64]]]]}}

Fossils

Microplants: Trematosphaeridium minor, T. holtedahlii, Polyporata obsoleta etc.


Age 

Earliest Nanhuan (latest Tonian) on schematic stratigraphic column (below early Cryogenian glacial).

Age Span: 

    Beginning stage: 
Tonian

    Fraction up in beginning stage: 
0.8

    Beginning date (Ma): 
776.00

    Ending stage: 
Tonian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
720.00

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.