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Yongning Formation

Yongning Fm

Period: 
Paleogene

Age Interval: 
Late Eocene, (26)


Province: 
Guangxi

Type Locality and Naming

The naming section is located in an area from Weicun Village and Maozi Village to Zhongqing Village northeast of Nanning City. Named the Yongning Series by T.H. Chu (Zhu Tinghu) in 1928.


Lithology and Thickness

Lower member is gray or grayish green and brownish gray mudstone, sandy mudstone, calcareous mudstone, muddy siltstone and calcareous siltstone, with 10–20 beds of lignite. Middle member is alternating beds of grayish green or light gray and variegated mudstone and sandstone, with brownish yellow sandy mudstone. Upper member is alternating beds of bluish gray or greenish gray and grayish green mudstone and siltstone, with several beds of lignite. The total thickness is ~700 m.


Lithology Pattern: 
Claystone


Relationships and Distribution

Lower contact

The lower part conformably overlies the Eocene Nadu Fm.

Upper contact

The upper part is mostly covered by the Quaternary.

Regional extent

This formation is mainly distributed at Tunli, Santang, Licai, Wutang, Weicun, Liantang and Zhongqing in the Nanning basin.


GeoJSON

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Fossils

The important fossils contained include more than ten species of ostracods such as Candona compressoformis, Chinocythere sinensis and Caspiolla sp. and the vertebrates Pseudobagrus sp., Crocodilus sp. and Heothema nanningensis.


Age 

Its age was previously considered to be Oligocene (Zheng et al., 1999). Recent study assigns this formation to the Late Eocene (Li et al., 2019). [Note: It is coeval with the Gongkang Fm in this same region that spans the Late Eocene (Priabonian Stage); therefore, for map-graphic purposes, shown as the lower portion of that interval.]

Age Span: 

    Beginning stage: 
Bartonian

    Fraction up in beginning stage: 
0.9

    Beginning date (Ma): 
38.04

    Ending stage: 
Priabonian

    Fraction up in the ending stage: 
0.5

    Ending date (Ma):  
35.81

Depositional setting

It is primarily fluvio-lacustrine-swampy deposits.


Depositional pattern:  

Additional Information


Compiler:  

Tao Deng, Yuanqing Wang, Qian Li, et al.