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Chijinqiao Formation
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Chijinqiao Fm base reconstruction

Chijinqiao Fm

Period: 
Cretaceous

Age Interval: 
Early Cretaceous, K1cjq, (13a)


Province: 
Gansu

Type Locality and Naming

The Chijinqiao Formation was named by Niu Shaowu (1987) after the geological mapping on the Jiuquan basin by the 2nd Geological Survey Team of the Geological Bureau of Gansu Province (1973-1975).


Lithology and Thickness

The Chijinqiao Formation is composed of a group of purple red, think bedded conglomerates and coarse sandstones. The grain size and thinness become bigger upwards generally. The lower part contains greenish yellow medium bedded sandstone and siltstone. Cross-bedding developed; middle-upper part is most composed of greenish yellow gravel-bearing sandstone and conglomerate; and the top interbedded with reddish siltstone and sandstone.

Figures: Chijinqiao Formation in Chijinqiao section of Jiuquan basin, Gansu]


Lithology Pattern: 
Aus conglomerate


Relationships and Distribution

Lower contact

It overlies unconformably on Cambrian granite. In Beishan region (north Gansu), the next older unit is the conglomerate of the Boluo Gr of late-Middle Jurassic.

Upper contact

Not given; but " The Chijinqiao Fm is of the same lithology as this Chijinbao Fm." (see that formation) suggests it is perhaps coeval or underlying?

Regional extent

The Chijinqiao Formation mostly occurs in the Chijinqiao area of Jiuquan City.


GeoJSON

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Fossils

None listed


Age 

Not given; but for graphic purposes; put below the Chijinbao Fm.

Age Span: 

    Beginning stage: 
Hauterivian

    Fraction up in beginning stage: 
0.5

    Beginning date (Ma): 
129.55

    Ending stage: 
Hauterivian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
126.50

Depositional setting


Depositional pattern:  


Additional Information


Compiler:  

Wan Xiaoqiao