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Tram Tau Formation

Tram Tau Fm

Period: 
Permian

Age Interval: 
Changhsingian, (8)


Province: 
West Bac Bo

Type Locality and Naming

Tram Tau area of Yen Bai Province; named by Nguyen Dac Dong, et al., 2000.

Synonym:


Lithology and Thickness

Mainly volcano-sedimentary beds bearing coal matter. Tram Tau section is 730 m of black-grey shale containing much coal matter, tuffaceous shale with some interbeds of tuffaceous sandy siltstone, rhyolite tuff, grading upwards into grey conglomerate, tuffaceous sandstone and some thin lenses of gray limestone and clayey limestone in the upper part.


Lithology Pattern: 
Volcanic ash


Relationships and Distribution

Lower contact

Pseudo-conformity relationship on the volcanics of the Tu Le Fm [according to text; but cross-section Fig. II.5.2 and Tu Le Fm entry suggests it overlies the Tram Tau Fm?]

Upper contact

Disconformable(?) below the Nghia Lo Fm.

Regional extent

Scattered in a window form within the Changhsingian volcanic cover of the Tu Le Rift.


GeoJSON

null

Fossils

Collected fossils include Rhipidopsis cf. R. panii, Schizoneura? sp., Taeniopteris sp. of Late Permian.


Age 

Based on the fossils, dated as Late Changshsingian, equivalent to the Yen Duyet Fm. However, SHIMP dating of the intrusive Ngoi Thia Complex Fm yielded a 256 ±4 Ma date, which would seem to imply an older age for the Tram Tau Fm host rock. There are also other yet-to-be-resolved problems with the age of the entire formation.

Age Span: 

    Beginning stage: 
Changhsingian

    Fraction up in beginning stage: 
0.5

    Beginning date (Ma): 
253.07

    Ending stage: 
Changhsingian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
251.90

Depositional setting


Depositional pattern:  

Additional Information


Compiler:  

Tran Van Tri and Vu Khuc (Editors; Geology and Earth Resources of Viet Nam, General Dept. of Geology and Minerals of Viet Nam; completed in Dec., 2011), with additional details from Tong-Dzuy Thanh and Vu Khuc (Editors; Stratigraphic Units of Viet Nam, 2nd edition; 2011; English edited by A. Boucot).