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Yikewusu Formation
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Yikewusu Fm base reconstruction

Yikewusu Fm


Period: 
Devonian

Age Interval: 
D21 (3), Middle Devonian


Province: 
Inner Mongolia

Type Locality and Naming

The type section is located at western Zhusilenghaierhan, north margin of Badanjilin Desert in western Inner Mongolia Autonomous Region. It was named by the Cooperative Research Group of Xi'an Institute of Geology and Mineral Resources and Ningxia Geological Team in 1977, and published by Zhang Yan in 1981.


Lithology and Thickness

The Formation can be divided into two parts:

Shale, sandstone. Lower part, 219.13 m thick, consists of alternations of brownish-yellow calcareous shale and yellowish-brown thin-bedded calcareous fine-grained sandstone.

Sandstone, limestone. Upper part, 567.04 m thick, is composed of grayish-brown thin-bedded calcareous fine-grained sandstone intercalated with sandy limestone and siliceous limestone and chert at the top,


Lithology Pattern: 
Fine-grained sandstone


Relationships and Distribution

Lower contact

The Formation rests conformably on the Zhusileng Fm and differs from the latter by its brown and yellowish colors in contrast to the Zhusileng Fm colors of grayish-green and purplish-red.

Upper contact

Conformable contact with the overlying Wotuoshan Fm.

Regional extent


GeoJSON

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Fossils

It contains brachiopoda Uncinulus spp., Skenidium polonicum, Undispirifer sp.; trilobite Coniproetus sp.; and coral Cyathophyllum sp., Tabulophyllum sp., Endophyllume sp.


Age 

Middle Devonian

Age Span: 
S

    Beginning stage: 
Eifelian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
394.30

    Ending stage: 
Eifelian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
385.30

Depositional setting


Depositional pattern:  


Additional Information


Compiler:  

(Hou Hongfei)