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AmuwusuBed Formation

AmuwusuBed Fm

Period: 
Neogene

Age Interval: 
Early Late Miocene (Tortonian), N1 , (12a)


Province: 
Inner Mongolia

Type Locality and Naming

The type section is located at the Amuwusu section (E112°44′, N42°22′), about 13 km west to Zhurihe town, Sonid Youqi County, central Nei Mongol. It was named by Qiu et al. (2013 in Wang et al., 2013).


Lithology and Thickness

Lower part of the Amuwusu Bed is characterized by a set of reddish-brown mudstones. Upper part is formed by greyish-yellow sandy mudstones and sandstones with gravels. It contains abundant mammalian fossils. Its thickness is less than 5 m.


Lithology Pattern: 
Claystone


Relationships and Distribution

Lower contact

No underlying rock units could be seen.

Upper contact

In Amuwusu type section, the Amuwusu Bed is overlain by the Holocene soils.

Regional extent

The bed is restricted in Zhurihe area, central Nei Mongol.


GeoJSON

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Fossils

Mammals: Mioechinus? gobiensis, Erinaceinae gen. et sp. indet., Yanshella sp., Soricinae gen. et sp. indet., Heterosoricinae gen. et sp. indet., Ansomys lophodens, Pseudaplodon amuwusuensis, Tamias ertemtensis, Spermophilinus mongolicus, Miopetaurista sp., Orientiglis wuae, Keramidomys magnus, Leptodontomys gansus, L. lii, Pentabuneomys feifari, Hystricops mengensis, Monosaulax tungurensis, Sinozapus parvus, Heterosminthus orientalis, Protalactaga grabaui, P. lophodens, Democricetodon lindsayi, Plesiodipus leei, P. robustus, Gobicricetdodon aff. G. flynni, G. robustus, G. arshanensis, Khanomys baii, Colloides xiaomingi, Prosiphneus qiui, Desmatolagus? sp., Ochotona spp.. (Qiu and Wang, 1999; Qiu and Li, 2016).


Age 

Based on the faunal mammals, the age of the Amuwusu Bed is normally considered as in early Late Miocene or the Bahean of Chinese Land Mammal Age (Deng, 2006; Qiu et al., 2006; Qiu et al., 2013 in Wang et al., 2013). T. Deng et al. (2019; Neogene chapter of China Integrated Stratigraphy and Timescale) show the age span as lower Tortonian with hiatus spanning basal Tortonian (but with wavy unconformity boundaries).

Age Span: 

    Beginning stage: 
Tortonian

    Fraction up in beginning stage: 
0.15

    Beginning date (Ma): 
10.97

    Ending stage: 
Tortonian

    Fraction up in the ending stage: 
0.5

    Ending date (Ma):  
9.44

Depositional setting

It is interpreted as a river-lake environment.


Depositional pattern:  

Additional Information


Compiler:  

Tao Deng, Sukuan Hou, J.Z. Qigao, Q. Li, Q.Q. Shi, B.Y. Sun, S.Q. Wang, F.X. Wu