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Dardong Formation
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Dardong Fm base reconstruction

Dardong Fm

Period: 
Devonian

Age Interval: 
D1 (23), Pragian (middle Early Devonian)


Province: 
Xizang (Tibet)

Type Locality and Naming

The type section is located at Dardong, 5 km north of Yongzhuqiao in Xainza County, Xizang Autonomous Region. It was named by Xia Daixiang in 1979.


Lithology and Thickness

Limestone. The formation is mainly composed of light- to dark-gray medium-bedded limestone, partly intercalated with bioclastic limestone and calcareous siltstone.

It is 500 m in thickness.


Lithology Pattern: 
Limestone


Relationships and Distribution

Lower contact

This formation overlies disconformably on the Dewukaxia Fm of the Lower Silurian.

Upper contact

This formation is overlain by the Deriangma Fm (Deri'angma Fm). But might be overlain by a Riaju Fm or Riadang Fm or Riarjue Fm on Lexicon charts (muddy limestone) and description of Langma Fm; none of which are in English Lexicon version.

Regional extent

It is mainly distributed at Dardong, Kerduo and Tarma of Xainza, northern Xizang Autonomous Region.


GeoJSON

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Fossils

It contains coral, brachiopods and tentaculites of the Nowakia acuaria zone.


Age 

Pragian (middle Early Devonian)

Age Span: 
S

    Beginning stage: 
Lochkovian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
419.00

    Ending stage: 
Pragian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
410.51

Depositional setting

It is interpreted as a deep-water basin facies.


Depositional pattern:  


Additional Information


Compiler:  

(Xian Siyuan)