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Bojiwan Formation

Bojiwan Fm

Period: 
Carboniferous

Age Interval: 
C21 (47, 48), middle Early Carboniferous


Province: 
Guizhou

Type Locality and Naming

The type section is located at Bojiwan, 3 km south of Weining County Seat, Guizhou. It was named by Ding Wenjiang in 1914.


Lithology and Thickness

Claystone and Volcanics. It is formed by varicolored shales and impure clayey limestone. According to the drilling data, below Bed 1 there are 89.4-m-thick olivine-bearing diabase and 26-m-thick dark-colored clayey sandstone, and beneath the sandstone are dark-gray marl and limestone. Reaching the maximum thickness of 600 m around Liudongqiao of Weining.


Lithology Pattern: 
Continental marl


Relationships and Distribution

Lower contact

Uncertain; the underlying strata are unexposed (core of an anticline). Regionally, coeval with Dawuba Fm, which has its next older unit as the Muhua Fm.

Upper contact

Conformable contact with the overlying Caohai Fm

Regional extent

Mainly outcrops around Caohai, Weining, with only the upper part seen at Shuicheng


GeoJSON

null

Fossils

Pseudouralinia sp.


Age 

Jiusian Age of the Early Carboniferous

Age Span: 

    Beginning stage: 
Visean

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
346.73

    Ending stage: 
Visean

    Fraction up in the ending stage: 
0.33

    Ending date (Ma):  
341.32

Depositional setting

It is interpreted as an extension of Luodian, Ziyun and the Langdai NE-trending sea trough, possibly belonging to sediments of confined gulf facies.


Depositional pattern:  


Additional Information


Compiler:  

Wang Hongdi