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Guohua Formation

Guohua Fm


Period: 
Triassic

Age Interval: 
Early Middle Triassic, (TJ104b)


Province: 
Guangxi

Type Locality and Naming

It was named by the district investigation team of Guangxi Geological Bureau in 1974. The named section is located in An Ning Tun, Guohua Township, Pingguo County, Guangxi.

Synonym:


Lithology and Thickness

Lower unit is tuff, dolomite, and oolitic tuff with a small amount of tuff, over which are tuff, mudstripe tuff, mud dolomite, and porous dolomite with a thin layer of mudstripe tuff, locally with tuff. In the lower unit, micro-stratigraphy, banded laminations, worm-like structures and sutures are developed. Upper unit is mainly flint-bearing agglomerate tuff, particulate tuff, and mudstripe tuff with a small amount of dolomite or dolomitic tuff. The thickness is 1057-1395 m.


Lithology Pattern: 
Volcanic ash


Relationships and Distribution

Lower contact

At the bottom, the bean-like tuff is in consolidated contact with the underlying Beisi Fm

Upper contact

At the top, the tuff and oolitic tuff are also in consolidated contact with the overlying Hekou Fm sandstone.

Regional extent

Only distributed in Guangxi Pingguo County, Guohua, Debao County, Duojing, Guliu and other places.


GeoJSON

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Fossils

Bivalves: Entolium sp., Neoschizodus sp., Promyalina sp., Unionites sp., Polygyrina sp., Posidonia sp., Chlamys sp.


Age 

The Proto-Guohua Formation represents the Anisian-age stratigraphy dominated by carbonates around Pingguo and Debao in Guangxi. Wang Zunzhou et al. (1992) thought that the upper part of this group produced Ladinian chrysolite, therefore, its age should be extended from the Anisian stage to the Ladinian stage. The original meaning (Anisian) is used in this dictionary.

Age Span: 

    Beginning stage: 
Anisian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
246.70

    Ending stage: 
Anisian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
241.46

Depositional setting

This group is semi-closed shallow water sediment.


Depositional pattern:  


Additional Information


Compiler:  

Zhang Shunxin, Jian Yuanping and Tong Jinnan.