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Raggyorcaka Formation
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Raggyorcaka Fm base reconstruction

Raggyorcaka Fm

Period: 
Permian

Age Interval: 
P3 (57), Lopingian Epoch (late Permian)


Province: 
Xizang (Tibet)

Type Locality and Naming

The type section is located on the southern bank of the Raggyorcaka about 10 km to the north of the Shuanghu Office of Tibet. It was named by Wen Shixuan in 1979.


Lithology and Thickness

Clastics. It is divisible into two parts. Lower part is composed of dark-grey sandy siltstone and limestone, yielding Fusulinida and brachiopods fossils, with a thickness of about 140 m. Upper part is composed of grey-black sandstone and siltstone, intercalated with coal seams, yielding plant fossils (phytolites), with a thickness of 90 m. Between the upper and lower parts there is a fault contact, with no distinct relationship between them.

Synonym: Rejaochaka Fm (as used in Triassic entry in Lexicon)


Lithology Pattern: 
Fine-grained sandstone


Relationships and Distribution

Lower contact

Unknown contact relationship with the underlying strata. Next older unit in this region is the middle-Permian Kamrbo Gr (its upper formation is the Ninggongqujiulong Fm)

Upper contact

Conformable contact with the overlying Kanglu Fm of the Lower Triassic

Regional extent

Distributed in the area extending from the Headquarters of Shuanghu Office of Tibet to the Raggyorcaka.


GeoJSON

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Fossils

The Fusulinida is characterized by the occurrence of the Palaeofusulina fauna, the Brachiopods comprise the Peltichia, Cathaysia, Squamularia, Spinomarginifera, Leptodus, etc., which are all the zonal fossils or important members of the Changhsing Fm in South China; the Plant fossils (phytolites) are including Selaginellites, Sphenophyllum, Annularia, Lobatannularia, Alethopteris, Compsopteris, etc., which are found to occur often in the Cathaysian flora of the Lopingian Epoch in South China.


Age 

Lopingian Epoch

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


Depositional pattern:  


Additional Information


Compiler:  

Wang Yujing

GeoJSON estimate by Longgang Ye and Yuyin Li (Chengdu Univ. Tech. students)