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Qiaotou Formation
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Qiaotou Fm base reconstruction

Qiaotou Fm

Period: 
Neoproterozoic

Age Interval: 
Early Nanhuan (Late Tonian-early Cryogenian), Nh (23, 24)


Province: 
Liaoning, Jilin

Type Locality and Naming

The name Qiaotou Fm is derived from the Qiaotou Quartzite named by Aoji. O. in 1928. The typical section is situated in Qiaotou of Qiaotou Town 12 km south of Benxi City, and the reference section is in Lidian to Lujuanzi in Wafangdian City, Liaoning Province.

[Figure: Type section of Qiaotou Fm]

Synonym: （桥头组）


Lithology and Thickness

The Qiaotou Fm is dominated by white gray and gray medium- to thick-bedded fine quartzite and glauconite quartzose sandstone interbedded with black and greenish yellow shale and sandy shale. The Qiaotou Formation has obvious sedimentary structures such as ripple marks, desiccation cracks, wavy bedding, gentle cross-bedding and lenticular bedding. The thickness in the Hunjiang area is 248 to 334 m, in Taizihe area is 34.6 to 172.1 m and in the Luda area is 175 to 1115 m.

[Figure: Stratigraphic Column of the Qiaotou Fm]


Lithology Pattern: 
Clayey sandstone


Relationships and Distribution

Lower contact

The basal part composed of grit (bears the shale shards derived from the underlying Nanfen Formation) rests disconformably (in Benxi area) or conformably (in Fuzhou and Luda area) on the underlying Nanfen Formation.

Upper contact

Regional extent

Eastern Liaoning Province. This formation is distributed in Hunjiang River basin of south Jilin, in Taizihe River Basin of east Liaoning and Fuzhou-Luda area in Liaodong Peninsula.


GeoJSON

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Fossils

It yields microplants: Margominuscula sp., Pseudozonosphaera sinica, polyporata obsoleta, Leiopsophosphaera aff. densa, L. infriata, L. minor, L. aperta, L. pelucida, Trachysphaeridium simplex, T. hyalinum, T. aff. minor, T. aff. chihsienense, T. cultum, T. incrassatum, T. planum, Taeniatum crassum, T. aff. simplex, Synsphaeridium conglutinatum, Zonosphaeridium minutum etc


Age 

Early Nanhuan (late-Tonian-early Cryogenian) indicated on schematic stratigraphic column. However, some publications on detrital zircons suggest it might be early Tonian (based on youngest redeposited zircons). Uncertain.

Age Span: 

    Beginning stage: 
Tonian

    Fraction up in beginning stage: 
0.8

    Beginning date (Ma): 
776.00

    Ending stage: 
Cryogenian

    Fraction up in the ending stage: 
0.2

    Ending date (Ma):  
703.00

Depositional setting


Depositional pattern:  


Additional Information

The glauconite K-Ar age is 629-656 Ma.


Compiler:  

Extracts from The Neoproterozoic Erathem (chapter in Stratigraphic Lexicon of China, draft of 2022) by Gao Linzhi, Ding Xiaozhong, Zhang Chuanheng, Zhang Heng.