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Eerdengaobao Formation

Eerdengaobao Fm

Period: 
Paleogene

Age Interval: 
Late Eocene , (12a)


Province: 
Inner Mongolia

Type Locality and Naming

The naming section is located at Urtyn Obo, Siziwang Banner, Inner Mongolia. Named by Pei Wenzhong, Zhou Mingzhen and Zheng Jiajian in 1963.

Synonym: Urtyn Obo Fm, Erden Obo Fm


Lithology and Thickness

Mainly sequence of grayish white pebbly conglomerate, fine sandstone and brick-red and brownish red sandy mudstone and mudstone. The thickness is ~20 m or more.


Lithology Pattern: 
Coarse-grained sandstone


Relationships and Distribution

Lower contact

Disconformable contact with the underlying Middle Eocene Shalamulun Fm (=Shara Murun Fm or Xar Moron Fm).

Upper contact

Disconformable contact with the overlying Late Eocene Huerjing Fm (Houldjin Fm).

Regional extent

This formation is distributed on steep slopes at Saruolamiao, Naogangdai, Urtyn Obo, Ganggai Obo, Bayan Obo (Wulangechu) and Cangrehasha (Balunsuo), Inner Mongolia. In addition, it is also exposed on both banks of the Xar Moron River from Damiao to Cangrehasha, subbasins in the vicinity of Bayan Hua and the Nomogen platform.


GeoJSON

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Fossils

Nearly 10 mammal fossils have been found in the formation, including Cadurcodon ardynense, Parabrontops gobiensis, Ardynia mongolensis, Schizotherium cf. avitum, Entelodon sp. and Amynodon alxaensis.


Age 

The age of this formation was suggested to be Early Oligocene in the past, but Wang (2019) et al. inferred it was Late Eocene.

Age Span: 

    Beginning stage: 
Priabonian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
37.71

    Ending stage: 
Priabonian

    Fraction up in the ending stage: 
0.5

    Ending date (Ma):  
35.81

Depositional setting


Depositional pattern:  


Additional Information


Compiler:  

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