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Dongqiaoenbulak Formation
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Dongqiaoenbulak Fm base reconstruction

Dongqiaoenbulak Fm

Period: 
Neoproterozoic

Age Interval: 
early-middle Qingbaikous (early Tonian), Qb （7）


Province: 
Xinjiang

Type Locality and Naming

Aksu-Kalpin region. The Dongqiaoenbulak Fm was named by Gao Zhenjia et al., in 1986 and was published by Lu Songnian in 1990. The typical section is located in the east of Qiaoenbulak Mountain, and the reference section is in the southwest of Yourmeinak village, Wushi County, Xinjiang Weiwuerzhu Zizhiqu (Xinjiang Uygur Autonomous Region). Lower-middle formation of Qiaoenbulak Gr.

Synonym: （东乔恩布拉克组）


Lithology and Thickness

The Dongqiaoenbulak Fm is dominated by grayish green massive polymictic conglomerate, intercalated with inequigranular pebbly greywacke and minor lithic arkose, in which developed abundant slump structures. Except a layer of pebbly sandstone at bottom, most of polymitic conglomerates are massive without beddings, which composed of the random accumulation of inequigranular pebbles, sand and mud. Some horizons have the deformation structures such as wrinkles, convolute beddings etc. The thickness of the Dongqiaoenbulak Formation ranges from 61 to 311 m.


Lithology Pattern: 
Aus conglomerate


Relationships and Distribution

Lower contact

It rests disconformably, locally conformably or unconformably on the underlying Xifangshan Fm

Upper contact

The top underlies conformably the overlying Muyangtan Fm

Regional extent

Aksu-Kalpin region. The area of distribution, similar to the Qiaoenbulak Gr, is mainly exposed north of Aksu, east of Posigeima Qiaoenbulak, south of Wushi, south of Yourmeinak, Fangshan and Sugetbulak area.


GeoJSON

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Fossils

The microclastic rock yields microplants: Trachysphaeridium rugosum, T. incrassatum, T. simplex, T. minor, Leiopsophosphaera aperta, L. densa, L. solida, Margominuscula aff. tennela, Pseudozonosphaera sinica, Macroptycha cf. uniplicata etc. Trace fossils are Chondrites sp. etc.


Age 

Strat column schematically shows as lower-middle quarter of Qingbaikous (lower Tonian

Age Span: 

    Beginning stage: 
Tonian

    Fraction up in beginning stage: 
0.2

    Beginning date (Ma): 
944.00

    Ending stage: 
Tonian

    Fraction up in the ending stage: 
0.3

    Ending date (Ma):  
916.00

Depositional setting

Lu Songnian et al. (1993) interpreted the facies as products of subaqueous gravity flow slumping in the deep-water channel of a submerged fan.


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.