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Yinping Formation
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Yinping Fm base reconstruction

Yinping Fm

Period: 
Neoproterozoic

Age Interval: 
late Qingbaikouan (late Tonian), Qb (40)


Province: 
Sichuan

Type Locality and Naming

Sichuan south of Gansu. The Yinping Fm was named by the Second Team of the Second Geological Survey Party of the Sichuan Bureau of Geology (1977), which was quoted in the Sichuan Regional Geology of Sichuan Province (1991). The type section is located in Yinping-Wugongkou, Mupi, Pingwu County, Sichuan Province. Uppermost formation of Bikou Gr in this region.

Synonym: （阴平组）


Lithology and Thickness

The Yinping Fm consists mainly of a series of metamorphosed clastic rocks with metamorphosed volcanic rocks. The lithological character is light gray, gray thin- to medium-bedded banded metamorphosed sandstone (garnet-mica-quartz schist or biotite sericite quartz schist) and gray, light gray-green metamorphosed siltstone (biotite sericite micrite schist and sericite quartz phyllite), the interbedded volcanic rocks are mainly gray, gray-green and purple basic volcanics, meta-acidic volcanics and tuffaceous microcrystalline schist. It is 1828-3536 m thick.


Lithology Pattern: 
Sandstone


Relationships and Distribution

Lower contact

The formation is disconformable or unconformable with underlying Baiyang Fm of the middle Bikou Gr, then Dashaba Fm of lower Bikou Gr.

Upper contact

The top of the Yinping Fm is conformable with the overlying Muzuo Fm (glaciomarine)

Regional extent

Sichuan south of Gansu. The Yinping Fm is distributed in Motian Mt. area, Pingwu, and is well developed from Yinping to Nijiagou, Qingchuan County, Sichuan Province.


GeoJSON

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Fossils


Age 

See age discussion for Bikou Gr and coeval Yangtianba Fm. Late Qingbaikouan (late Tonian) in schematic stratigraphic column.

Age Span: 

    Beginning stage: 
Tonian

    Fraction up in beginning stage: 
0.55

    Beginning date (Ma): 
846.00

    Ending stage: 
Tonian

    Fraction up in the ending stage: 
0.8

    Ending date (Ma):  
776.00

Depositional setting


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.