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Bolong Formation
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Bolong Fm base reconstruction

Bolong Fm

Period: 
Neoproterozoic

Age Interval: 
Nh （11）


Province: 
Xinjiang

Type Locality and Naming

Tieklik region (SW Tarim Basin). The Bolong Fm was named by Ma Shipeng et al., in 1979 and was formally published in 1989. The typical section is located in Bolong in the west of the Xinjiang-Tibet Road, in the south of Yecheng County, Xinjiang Weiwuerzhu Zizhiqu (Xinjiang Uygur Autonomous Region). Lower formation of the Qiakmakelik Gr.

Synonym: （波龙组）

[Figure: The type-section of the Bolong Formation in West Kunlun. a-The section of the Bolong Formation; b-Siliceous rocks, the bottom of the Bolong Formation; c,d-Diamictites]


Lithology and Thickness

The Bolong Fm is the formation of marine glacial rock (diamictite), which is dominantly composed of gray massive moraine-type diamictite intercalated with siliceous mudstone, siltstone, shale, turbiditic sandstone and detrital flow breccia. The thickness varies from 500 to 1216 m.


Lithology Pattern: 
Glacial till


Relationships and Distribution

Lower contact

The Bolong Formation disconformably overlies the Yalaguz Fm

Upper contact

It is conformably overlain by the varvite of the overlying Kelixi Fm

Regional extent

Tieklik region (SW Tarim Basin). It is dominantly distributed in the southwest of Yecheng County in the north slope of West Kunlun, Heluostan River, Qipan River, Qiakmakelik Valley in the west of the Xinjiang-Tibet Road and south of Pishan County.


GeoJSON

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Fossils

It yields abundant microplants (including 30 genera and 39 species), dominated by Leiopsophosphaera sp., Protoleiosphaeridium sp. Leiominuscula sp., Zonosphaeridium sp., Nucellosphaeridium sp., Macroptycha sp., in addition, Trachysphaeridium sp., Taeniatum sp. etc.


Age 

A SHRIMP U-Pb dating of 756 Ma is found in the Bolong Formation (Gao Linzhi et al., 2013). Therefore, assumed here as equivalent to the major Sturtian glacial of lower Cryogenian.

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: 
0.8

    Ending date (Ma):  
652.00

Depositional setting

Marine glacial rocks (diamictite)


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.