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Xiaoxihe Formation
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Xiaoxihe Fm base reconstruction

Xiaoxihe Fm

Period: 
Neoproterozoic

Age Interval: 
Nanhuan (Cryogenian), Nh (51)


Province: 
Anhui

Type Locality and Naming

West Anhui (Dabie Mts.). The Xiaoxihe Formation was named by the Anhui Party of Regional Geological Survey. The naming section is located at Xiaoxihe of Huoshan County, Anhui Province. The only surface-exposed formation in the Foniling Gr.

Synonym: （小溪河组）


Lithology and Thickness

The Xiaoxihe Fm consists mainly of alkali basalt, tuff and sandy mudstone, which have undergone strong deformation and metamorphism to form different types of schist and gneiss. Because of later granite intrusions and late deformation and metamorphism, the thickness of the formation is difficult to estimate.


Lithology Pattern: 
Volcanics


Relationships and Distribution

Lower contact

Regionally on the stratigraphic column, the underlying units (not exposed at surface) in this Foniling Gr are Mesoproterozoic?

Upper contact

Regionally on the stratigraphic column, the next higher formation is Late Carboniferous in age.

Regional extent

West Anhui (Dabie Mts.). The formation is mainly distributed in Zhuanbuyuan, Xiaoxihe of Huoshan County and Qilihe, Hepeng of Shucheng County. Some exposures are in Niujiaochong of Huoshan and the north slope of Zhifeng Hills.


GeoJSON

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Fossils


Age 

The isotopic age (U-Th-Pb) of zircons from K-spar gneissic granite are 590-781 Ma by the Anhui Party of Geological Survey in 1974 and are 732-764 Ma as acquired by Zhang Peng (1992). Therefore, the country rocks are Sinian or older than Sinian. Middle and Late Nanhuan (Cryogenian) tentatively shown on schematic stratigraphic column (dotted).

Age Span: 

    Beginning stage: 
Cryogenian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
720.00

    Ending stage: 
Cryogenian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
635.00

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.