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Hongyashan Formation
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Hongyashan Fm base reconstruction

Hongyashan Fm

Period: 
Cretaceous

Age Interval: 
Late Cretaceous, (7b) K2hy


Province: 
Xizang (Tibet)

Type Locality and Naming

The Hongyashan Formation was designated by Wang Naiwen in 1983. The section for the designation is in Guiya of the Baingoin County, Xizang (89°36′; 31°50′). The reference section is in Boboyala of the Baingoin County, Xizang (89°50′; 31°45′).


Lithology and Thickness

The Hongyashan Formation is represented by mainly light red medium-bedded calcareous algae limestone, locally with medium-grained sandstone. The Formation is in excess of 400 m in thickness.


Lithology Pattern: 
Reef limestone


Relationships and Distribution

Lower contact

The contact relationship between the base of the formation and its underlying Pingtaboluo Fm is unknown.

Upper contact

Uncertain. [Cret Lexicon original text said "unconformably under the purple red conglomerate of the overlying Jinzhushan Fm (Jingzhushan Fm)", but that formation is of coeval age in adjacent region (Cret column 7a).

Regional extent

The present formation occurs in a limited area and is only found in the Guiya and Bobogyala areas. It is persistent in lithology.


GeoJSON

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Fossils

In the Guiya and Boboyala areas it yields bivalves Bournina tibetica, Hipparitidae, etc. small-sized gastropods, calcareous algae Acicularia americana, Cymopolia tibetica, Trinocladus megaclodus, etc.


Age 


Age Span: 

    Beginning stage: 
Santonian

    Fraction up in beginning stage: 
0.75

    Beginning date (Ma): 
84.16

    Ending stage: 
Maastrichtian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
66.04

Depositional setting


Depositional pattern:  


Additional Information


Compiler:  

Wan Xiaoqiao