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Maichuqing Formation

Maichuqing Fm

Period: 
Triassic

Age Interval: 
Middle-late Late Triassic, (TJ49)


Province: 
Yunnan

Type Locality and Naming

The type section is located between Maichuqing Village and Waigu Village, Dacang District, Weishan County, Yunnan Province. It was named by Yunnan Geological Bureau in 1973.

Synonym:


Lithology and Thickness

Lower part is thick medium-grained arkose with a thickness of about 100 m. It is mainly composed of gray, gray-black thin siltstone and mudstone, with thin coal seam and carbonaceous shale in the middle and upper part. The lithology of this formation is stable and the thickness is generally 258-890 m.


Lithology Pattern: 
Siltstone


Relationships and Distribution

Lower contact

It is disconformable in contact to the underlying the Waluba Fm

Upper contact

It is conformable with the overlying Lower Jurassic Tongyangjiang Fm

Regional extent

It is distributed in the Lanping-Simao area, Yunnan Province. It is distributed in the Weishan area, with a thickness of 100 m and about 500 m in the Mojiang and Lvchun area. The stratigraphy of the Bagong Fm in Yunling area and Lamaya Fm in Muli area is similar to this formation.


GeoJSON

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Fossils

Bivalves: Yunnanophorus, Indosinion, Modiolus; plants: Clathropteris meniscioides, Todites shensiensis; conchostracans and ostracods.


Age 

Schematic stratigraphic section suggests span of mid-Norian through Rhaetian.

Age Span: 

    Beginning stage: 
Norian

    Fraction up in beginning stage: 
0.5

    Beginning date (Ma): 
216.52

    Ending stage: 
Rhaetian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
201.36

Depositional setting


Depositional pattern:  


Additional Information


Compiler:  

Zhou Huiqin, Sun Xin and Tong Jinnan.