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Duantouya Formation
Click to display on map of the Ancient World at:
Duantouya Fm base reconstruction

Duantouya Fm

Period: 
Neoproterozoic

Age Interval: 
Nanhuan (Cryogenian), Nh (41-a)


Province: 
Shaanxi

Type Locality and Naming

West Shaanxi. The Duantouya Fm was named by the Qinling Party of Regional Geological Survey (Shaanxi Bureau of Geology and Mineral Resources) in 1967. The typical section is situated in Duantouya, Lueyang County and the reference section is in Chadian and Banjiashan in Mianxian County, Shaanxi Province.

Synonym: （断头崖组）


Lithology and Thickness

In the typical area (Lüyang County), the Lower part of the Duantouya Fm is dominated by coarse clastic rock, including grayish green sandy conglomerate cemented by pyroclasts or sandy mud (28-49 m). Upper part is composed of magnesium carbonate (dolomitic) rock intercalated with slate, phosphate clastic rock, manganiferous limestone and phosphorite. in the east Mianxian area, the upper part has a persistent lithology, and the lower part is pebbly sandstone and sandy shale; and in Ningqiang County, it becomes tuffaceous sandstone-conglomerate intercalated with phyllite. Total thickness varies from 221 to 1110 m.


Lithology Pattern: 
Sandy limestone


Relationships and Distribution

Lower contact

The lower part rests unconformably on the underlying Bikou Gr

Upper contact

The top is conformably overlain by the Jiudaoguai Fm

Regional extent

West Shaanxi. It is dominantly distributed in Hejiaya, Duantouya of Lueyang County, in Hongyangou, Huiduishan and Jigongshi of Mianxian County, and in Xuehua, Taiping, Dongfanggou and Shapogou of Ningqiang County.


GeoJSON

{"type":"Feature","geometry":{"type":"MultiPolygon","coordinates":[[[[106.02,33.22],[106.43,33.21],[106.77,33.12],[106.91,33.04],[106.8,32.89],[106.55,32.83],[105.85,32.48],[105.85,32.54],[105.69,32.78],[105.55,32.94],[105.45,32.99],[105.39,33.04],[105.22,33.12],[105.1,33.15],[106.02,33.22]]]]}}

Fossils

The phosphorite in the Mianxian area yields microplants: Trematosphaeridium minutum, T. holtedahlii etc.


Age 

Nanhuan (Cryogenian) on schematic stratigraphic column.

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.