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Chahe Formation
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Chahe Fm base reconstruction

Chahe Fm

Period: 
Neoproterozoic

Age Interval: 
Early Sinian (early Ediacaran), Z （43）


Province: 
Hubei

Type Locality and Naming

North-central Hubei. The Chahe Fm was named by the Institute of Regional Geological Survey, Hubei Bureau of Geology and Mineral Resources in 1982. The typical section is located at Xitouwan of Chahe, 4 km east of Sanyangdian, Jingshan County, Hubei Province.

Synonym: （岔河组）


Lithology and Thickness

The Chahe Fm is subdivided into three lithologic parts. Lower part is white gray and yellowish gray siliceous or pelitic slate intercalated with dolomite. Middle part is yellowish gray pelitic slate intercalated with yellowish gray meta-siltstone and lenticular microcrystalline dolomite. Upper part is dominantly composed of dark gray medium-bedded siltstone, calcareous slate, silty slate and thick-bedded laminated pelitic limestone intercalated with fine-crystalline limestone. The total thickness varies from 64 to 1006 m.


Lithology Pattern: 
Shallow-marine marl


Relationships and Distribution

Lower contact

The lower part rests unconformably on the underlying Yaolinghe Fm

Upper contact

The top is conformably overlain by the Baizhaoshan Fm

Regional extent

North-central Hubei, Wudang Mtns. It is dominantly exposed south of Suixian County and north of Jingshan and Anlu Counties. In addition, in Qingtan-Dabeidian of Zaoyang County, Heiwuwan, Shangshi north of Suixian County, and Haodian of Yingshan County.


GeoJSON

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Fossils


Age 

Early Sinian (early Ediacaran) on schematic stratigraphic column.

Age Span: 

    Beginning stage: 
Ediacaran

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
635.00

    Ending stage: 
Ediacaran

    Fraction up in the ending stage: 
0.5

    Ending date (Ma):  
586.90

Depositional setting

The lithology, thickness and metamorphic grade are obviously varied with the strike, of which the limestone and slate contain abundant carbonaceous matter in Sanlidian area in Anlu County, but in the south of Suixian, the lithologic facies changes to biotite quartz-schist intercalated with microcrystalline dolomite with a thickness of 273 m, in Shipansi of Zaoyang, it is composed of pyritized two-mica quartz-schist intercalated with very fine-grained limestone and chert, with a thickness of 64 m.


Depositional pattern:  


Additional Information


Compiler:  

Extracts from The Neoproterozoic Erathem (chapter in Stratigraphic Lexicon of China, draft of 2022) by Gao Linzhi, Ding Xiaozhong, Zhang Chuanheng, Zhang Heng.