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Caodaban Formation
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Caodaban Fm base reconstruction

Caodaban Fm

Period: 
Neoproterozoic

Age Interval: 
Sinian (Ediacaran), Z （15）


Province: 
Gansu, Inner Mongolia

Type Locality and Naming

Longshou Mts. (border central Gansu to Inner Mongolia). The Caodaban Fm was named by the Gansu Party of Geomechanics and Regional Geological Survey in 1981 and was formally published by Gansu Bureau of Geology and Mineral Resources in 1989. The typical section is located in Caodaban of Hanmushan, Yongchang County, Gansu Province. Upper formation of the Hanmushan Gr.

Synonym: （草大板组）


Lithology and Thickness

The Caodaban Fm is subdivided into two members. Lower member is greenish gray to dark gray pelitic limestone, calcareous phyllite, metamorphic quartzose sandstone, generally with sandy phosphorite in the base, which change facially can to gray banded limestone, pelitic or carbonaceous limestone and phyllite following the strike. Upper member is composed of gray, white-gray and yellowish gray massive limestone, pelitic banded limestone intercalated with oolitic, pseudo-oolitic, edgewise, brecciated limestone, andesitic tuffaceous phyllite. The lower member varies from 626 to 855 m in thickness. The upper member is thickness of 191 to 805 m.


Lithology Pattern: 
Limestone


Relationships and Distribution

Lower contact

The lower part, gray slate and thin-bedded limestone, overlies conformably the calcareous phyllite of the underlying Shaohuotonggou Fm

Upper contact

The upper part is imperfectly exposed. Middle Devonian is indicated on the stratigraphic column.

Regional extent

Longshou Mts. (border central Gansu to Inner Mongolia). With a near east to west distribution, the Caodaban Fm is intermittently distributed in Qingshiyao, Hanmushan, Hongyanshan and Qingshan areas and the thickest part is in Hanmushan area.


GeoJSON

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Fossils

The Caodaban Fm yields microplants: Leiopsophosphaera sp., Synsphaeridium sp., Leiofusa sp., Laminarites sp., Asperatopsophosphaera sp. etc.


Age 

Sinian (Ediacaran) span on the schematic stratigraphic section.

Age Span: 

    Beginning stage: 
Ediacaran

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
635.00

    Ending stage: 
Ediacaran

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
538.80

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.