Home Multi-Country Search About Admin Login
Cenozoic
Cretaceous
Jurassic
Triassic
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
Neoproterozoic
Mesoproterozoic

Search by
Select Region(s) to search
Hold Ctrl (Windows/Linux) or Command (Mac) to select multiple
Tongchangkou Formation
Click to display on map of the Ancient World at:
Tongchangkou Fm base reconstruction

Tongchangkou Fm

Period: 
Neoproterozoic

Age Interval: 
Early Nanhuan (early Cryogenian), Nh (5, 6)


Province: 
Gansu, Inner Mongolia

Type Locality and Naming

Beishan. The Tongchangkou Fm was named by Tan Guangzhong, Zhao Wenjie and Yu Yisheng in 1981, and was published by Gao Zhenjia (1985). The type section is located in Tonchangkou-Dahuoluo Mt. area north of Qiaowan, Subei Mongolian Autonomous County, Gansu Province.

Synonym: （通畅口组）


Lithology and Thickness

The Tongchangkou Fm consists of light gray to gray-white thick-bedded dolomite with abundant siliceous bands and with dolomitic limestone rich in stromatolites and interbedded with yellowish gray dolomite or rose thin- to medium-thick-bedded argillaceous limestone or brecciated conglomerate. A basal conglomerate is found locally. Along the strike westwards from the type section, clastic rocks increase gradually and there appear interbeds of dolomitic limestone forming locally dolomite mineral deposits with gypsum. The thickness ranges from 1300 to 2261 m.


Lithology Pattern: 
Dolomitic limestone


Relationships and Distribution

Lower contact

The formation is disconformable onto the underlying Dahuoluoshan Fm (Qingbaikouan = Tonian), the upper formation of the Yuanzaoshan Gr

Upper contact

It is unconformably overlain by the Xiyangchang Fm tillite (late Cryogenian), which overlaps on different horizons of the formation.

Regional extent

Beishan. Inner Mongolia and northernmost Gansu. The Tongchangkou Formation is mainly distributed in Tongchangkou and Dahongshan on northwest slope of Dahuoluo Mountains at the juncture of Gansu and Xinjiang, and eastwards to Wangxu Mountain and Xichangjing in Ejin Qi, Inner Mongolia.


GeoJSON

{"type":"Feature","geometry":{"type":"MultiPolygon","coordinates":[[[[96.51,42.68],[98.16,42.5],[98.93,41.93],[100.23,41.34],[100.68,40.84],[101.01,40.18],[100.79,39.86],[99.93,40.09],[98.78,40.54],[97.16,41.04],[96.07,41.52],[94.52,42],[92.86,42.6],[92.16,43.18],[92.42,43.59],[93.14,43.71],[95.16,43.44],[96.51,42.68],[103.02,42],[104.41,41.75],[109.96,42.47],[111.57,43.44],[113.29,43.17],[113.39,42.57],[112.83,41.33],[110.12,40.81],[109.04,40.78],[107.73,40.59],[106.49,39.52],[105.92,39.39],[104.9,38.98],[104.61,39.14],[104.49,39.6],[104.19,39.93],[102.44,40.31],[101.84,41.4],[100.69,41.6],[99.62,42],[99.95,42.46],[100.98,42.53],[101.96,42.28],[103.02,42]]]]}}

Fossils

Stromatolites are Tungussia Levis, Gymnosolen gracilis, G. Minutissimus, G. Diuaricatus, Linella auis, Deserticola irregularis, Cryptozoon f.


Age 

Early Nanhuan (latest Tonian) on stratigraphic chart. For graphic purposes to indicate top uniformity (scouring before deposition of overlying tillite?) and the apparent lack of an early-Cryogenian till unit, then drawn here as spanning the Nanhuan pre-Sturtian glacial.

Age Span: 

    Beginning stage: 
Tonian

    Fraction up in beginning stage: 
0.8

    Beginning date (Ma): 
776.00

    Ending stage: 
Tonian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
720.00

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.