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Xiaolianggou Formation

Xiaolianggou Fm


Period: 
Silurian

Age Interval: 
lower Wenlock of Llandovery (S2); (39, 40)


Province: 
Gansu

Type Locality and Naming

It was named by Fu Lipu et al in 1983. The type section is located at Xiaolianggou, the branch gully of Miaogou in Zhouqu County, Gansu Province.

Synonym: (小梁沟组)


Lithology and Thickness

The formation consists of grayish black and black calcareous carbonaceous slate intercalated with gray to light gray, argillaceous banded limestone. It is 175 m in thickness


Lithology Pattern: 
Pelagic marl


Relationships and Distribution

Lower contact

The formation rests conformably onto the underlying Jiannigou Fm

Upper contact

The formation rests conformably below the overlying Maer Fm

Regional extent

In west, at Zhanwaxiang Township in Zoigê County, the formation is dominated by sandy-pelitic sediments and siliceous rock of 407-467 m in thickness. The thickness of the formation decreases to 119 m at the Nanshimengou section in Zhouqu County, Gansu Province.


GeoJSON

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Fossils

The formation yields graptolites, anthozoa, brachiopod, trilobite, bryozoa and gastropod, etc., such as graptolites Cyrtograptus sakmaricus, C. cf. bohemicus, C. cf. insectus ellailla, Propora sp., Falsicatenipora dazhubaensis, Halysites yumenensis, Taxopora salairica, Mesosoleniella gannanensis, Mesofavosites regularis, M. multiporus, etc.; brachiopods Aegiria sp., Strophochonetes sp.; gastropod Michelinoceras valens, etc.


Age 


Age Span: 

    Beginning stage: 
Sheinwoodian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
432.93

    Ending stage: 
Homerian

    Fraction up in the ending stage: 
0.0

    Ending date (Ma):  
430.62

Depositional setting


Depositional pattern:  


Additional Information


Compiler:  

Wang Chuanshang and Wang Xiaofeng