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Lengjiaxi Gr
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Lengjiaxi Gr base reconstruction

Lengjiaxi Gr

Period: 
Neoproterozoic

Age Interval: 
Early Qingbaikouan (early Tonian), Qb (54, 58, 59)


Province: 
Hunan

Type Locality and Naming

Central-north Hunan. The Lengjiaxi Gr was named by Wang Xiaoqing (Wang, H. C.) and Liu Zuyi in 1936. The type locality is the Lengjiaxi Village, Taoyuan County, Hunan Province.

In northwest Hunan (column 59), the Lengjiaxi Gr consists of three formations in ascending order– HuangXudong Fm, Xiaomuping Fm, and Dayaogu Fm. [No separate details on these.].

Synonym: （冷家溪群） Xiushui Gr is a synonym


Lithology and Thickness

The Lengjiaxi Gr is characterized by a monotonous lithology. It consists of rhythmic interbedding of slate, sandy slate, silty slate, striped slate and other fine clastic rock, sandwiched with minor greywacke, metamorphosed tuffaceous sandstone and feldspar quartz sandstone except the Nanqiao Fm, which contains volcanic rock. The volcanic intercalations are tholeiite. The total thickness varies from 6700 m to 10127 m. In Yuanling-Anhua,

[Figure: Lithology of the Lengjiaxi Gr]


Lithology Pattern: 
Sandy claystone


Relationships and Distribution

Lower contact

Bottom is not seen.

Upper contact

The top is covered unconformably by the Banxi Gr = Madiyi Fm (northwest Hunan), Gaojian Fm (western Hunan border to Guizhou) or the Liantuo Fm.

Regional extent

North and northwest Hunan. The Lengjiaxi Gr is mainly in the areas from Hengdong to Linxiang, Taoyuan, Anhua, and Tongcheng, Hunan Province.


GeoJSON

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Fossils

Microplants: Leiopsophosphaera and Asperatopsophosphaera.


Age 

SHRIMP U-Pb dates have been acquired of 862±6 Ma and 829±26 Ma (Gao Linzhi et al., 2012). Early Qingbaikouan (early Tonian) on schematic stratigraphic column.

Age Span: 

    Beginning stage: 
Tonian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
1,000.00

    Ending stage: 
Tonian

    Fraction up in the ending stage: 
0.4

    Ending date (Ma):  
888.00

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.