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Laba Formation
Click to display on map of the Ancient World at:
Laba Fm base reconstruction

Laba Fm

Period: 
Permian

Age Interval: 
P2-3 (56), Changhsingian Stage (late Lopingian Epoch, latest Permian), but maybe includes older strata.


Province: 
Yunnan

Type Locality and Naming

The type section is located at the Nanpan of the Lancang County, Yunnan Province (99°42′, 22°37′). It was named by the Regional Geological Reconnaissance Party of Yunnan Province in 1982, and was cited officially by the Yunnan Provincial Bureau of Geology and Mineral Resources (1990).


Lithology and Thickness

Clastics and Chert. Lower part is composed of yellow-green and purplish red shale and radiolarian siliceous rocks, intercalated with quartz-sandstone and marl lenses. Middle part is composed of quartz-sandstone, intercalated with shale, yielding plant fossils (phytolites) fragments. Upper part is composed of black chert, siliceous shale and purplish-red shale, intercalated with quartz-sandstone, representing fracture-subsidence-zone and deep-water turbidite.


Lithology Pattern: 
Chert


Relationships and Distribution

Lower contact

Unconformable contact with the underlying Nanduan Gr (or seems that way on chart)

Upper contact

Unknown contact relationship with the overlying strata

Regional extent

Distributed in a South-North-trend in the areas of Gengma, Cangyuan, the southern bank of the Lancang River and the Menglian County.


GeoJSON

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Fossils

Lower part yields Fusulinida represented by Neoschwagerina sp.; Conodonts such as Mesogondolella? idahoensis, etc.


Age 

Changhsingian and maybe including older? The age of the fossils should range from the Late Carboniferous Epoch to the Changhsingian Stage of the Late Permian Period. It is obvious that there are some redeposited fossils whose age should not belong largely to the Changhsingian Stage.

Age Span: 

    Beginning stage: 
Wuchiapingian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
259.55

    Ending stage: 
Changhsingian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
251.90

Depositional setting

Upper part is interpreted as a "fracture-subsidence-zone" and deep-water turbidites.


Depositional pattern:  


Additional Information


Compiler:  

Shang Ringhua

GeoJSON estimate by Runan Yong, Suxiao Li and Wen Li (Chengdu Univ. Tech. students)