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Zhidan Gr
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Zhidan Gr base reconstruction

Zhidan Gr

Period: 
Cretaceous

Age Interval: 
Early Cretaceous, K1zG, (16)


Province: 
Shaanxi, Inner Mongolia, Gansu, Ningxia

Type Locality and Naming

Ordos Basin. Pan Zhongxiang erected the Baoan series in 1934. The type locality is in the Baoan County of north Shaanxi (Now called the Zhidan County). Reference section is located in the area extending from Binxian County, Sha’anxi Province, to Jinghe River of Jingchuan County, Gansu Province. Upward succession of the Yijun Fm, Luohe Fm, Huanhe Fm, Luohandong Fm, Jingchuan Fm and Dongshen Fm.

Synonym:（保安群）, Bao'an Gr, Baoan Gr.


Lithology and Thickness

Lower part of the present group is built up by purple gray conglomerate; Middle part purple red sandstone with shale; Upper part red and variegated sandstone interbedded with mudstone. See component formations for details


Lithology Pattern: 
Sandstone


Relationships and Distribution

Lower contact

The base, marked by gravel-bearing sandstone, lies disconformably on the underlying Middle Jurassic Dingan Fm, or the conglomerates of the Late Jurassic Fenfanghe Fm

Upper contact

The top part, comprising loess-like red siltstone and sandy mudstone, lies unconformably under the overlying Pliocene

Regional extent

It is extensively distributed in Inner Mongolia (Nei Monggol), Shaanxi, Gansu and Ningxia of the Shaanxi-Gansu- Ningxia basin.


GeoJSON

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Fossils

See component formations.


Age 

In some publications, this group is referred to Late Jurassic or to Late Jurassic-Early Cretaceous in age. Shown as mid-Berriasian through Aptian by Dangpeng Xi, Xiaoqiao Wan, et al. (2019; Integrated Stratigraphy and TimeScale of China).

Age Span: 

    Beginning stage: 
Berriasian

    Fraction up in beginning stage: 
0.5

    Beginning date (Ma): 
140.40

    Ending stage: 
Aptian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
113.20

Depositional setting

See component formations.


Depositional pattern:  


Additional Information


Compiler:  

Wan Xiaoqiao