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Waduo Formation

Waduo Fm


Period: 
Triassic

Age Interval: 
Late Triassic, (TJ74)


Province: 
Sichuan

Type Locality and Naming

The Sichuan District Investigation Team named this formation in 1981. The named section is located in Waduo, Yahui County, Sichuan Province.

Synonym: A set of carbonate basic volcanic flysch clastic rocks in the Daofu area corresponding to this formation is named as Runiangu Fm by Sichuan Bureau of Geology and Mineral Resources (1987, 1: 200, 000 Kangding District report), and the Waduo Fm. and Runiangu Fm. are regarded as contemporaneous difference facies. Hou Liwei et al. (1991) used these two formations and their meanings.


Lithology and Thickness

Metamorphism sandstone is interbedded with dark gray thick layer massive silty sandstone and slate. The thickness of Waduo Formation is more than 2000 m and develops striated and banded structure, it is characterized by muddy flysch and turbidite deposits.


Lithology Pattern: 
Fine-grained sandstone


Relationships and Distribution

Lower contact

The dark gray slate at the bottom is in conformity with the underlying Zhuwo Fm of Upper Triassic, which is characterized with black and white sandstone and slate.

Upper contact

Conformable with the overlying Lianghekous Fm

Regional extent

This formation is mainly distributed in the areas of Yajiang and Xinlong in Sichuan Province, in the Luhuo, Daofu Fault Zone, the formation is composed of gray, gray-white breccia limestone, purple red bioclastic breccia limestone, dolomite interbedded with green basalt, basalt breccia and basaltic fused breccia, it forms the carbonate rock-basic volcanic flysch clastic rock hybrid rock band.


GeoJSON

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Fossils

Breccia limestone contains a large number of brachiopods, corals, conodont, bivalves and gastropods. The time limit is from Silurian to Late Triassic. Late Triassic bivalves: Halobia pluradiata, H. superbescens, H. yunnanensis, H. yandongensis, Pergamedia eumenea, etc.


Age 

The Waduo Formation is dated from late Carnian to early Norian of Late Triassic.

Age Span: 

    Beginning stage: 
Carnian

    Fraction up in beginning stage: 
0.65

    Beginning date (Ma): 
230.70

    Ending stage: 
Norian

    Fraction up in the ending stage: 
0.15

    Ending date (Ma):  
224.07

Depositional setting

Muddy flysch and turbidite deposits


Depositional pattern:  


Additional Information


Compiler:  

Zhang Shunxin, Yu Yingyue and Tong Jinnan.