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Baowan Formation
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Baowan Fm base reconstruction

Baowan Fm

Period: 
Cretaceous

Age Interval: 
Late Cretaceous, K2bw, (43a)


Province: 
Guangdong, Hainan

Type Locality and Naming

The No.764 Geological Team of the Guangdong Bureau of Geology and Mineral Resources erected the Baowan Group in 1964. Its type section is in the Baowan Village of Dingan County, Guangdong Province. The Baowan Group consists of 5 purple red, purple gray and gray green sedimentary cyclothems and was assigned to Late Cretaceous. In 1991 the Sichuan Panxi-Hainan Regional Geological Investigation Team called it the Baowan Formation and also assigned it to Late Cretaceous.


Lithology and Thickness

Lithologically it is mainly represented by purple red, purple, gray purple and gray yellow polymineralic conglomerate, sandstone, siltstone and mudstone, constituting cyclothems. The top of the formation is unknown. The formation is 816 m thick.


Lithology Pattern: 
Coarse-grained sandstone


Relationships and Distribution

Lower contact

Purple red clayey sandstone at the base of the formation contacts conformably with purple red tuff with volcanic breccia of the underlying Lumuwan Fm (Lumuwan Gr). It contacts unconformably the underlying Lower Triassic Qinwen Fm.

Upper contact

It contacts unconformably with the overlying Paleocene Changtou Fm.

Regional extent

The Baowan Formation is distributed in the Baisha-Ledong basin of the Hainan Island, the Changmao Reservoir and Daozilin.


GeoJSON

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Fossils

The formation yields Ostracods Cypridea sp., Cyprinotus sp., Lycopterocypris sp.; sporopollen Triporopollenites sp., Tricolpites sp., and Triptyches sp.


Age 


Age Span: 

    Beginning stage: 
Turonian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
93.90

    Ending stage: 
Maastrichtian

    Fraction up in the ending stage: 
0.1

    Ending date (Ma):  
71.56

Depositional setting

It is of fluvial-lacustrine sedimentation


Depositional pattern:  


Additional Information


Compiler:  

Wan Xiaoqiao