Na Vang Fm

Period:

Permian

Age Interval:

Wuchiapingian, (9)

Province:
Viet-Laos NW

Type Locality and Naming

Lai Chau Province from the Vietnam-China boarder through Na Vang and Ban Mao village areas. Named by To Van Thu et al., 1996.

Synonym: Some works consider it to be the Upper part of Bac Son Fm (due to similarity of limestone sediment composition and fossils)

Lithology and Thickness

About 150-200 m of only limestone. Lower part is darker grey, upper part is lighter grey; dolomitized in some places.

Lithology Pattern:

Limestone

Relationships and Distribution

Lower contact

Conformable upon the Ban Diet Fm. Partly coeval with the Song Da Fm in Lai Chau Province.

Upper contact

Not yet observed. Next higher regional unit is the mid-Triassic La Chau Fm or the Cam Thuy volcanics of late Wuchiapingian (southeast Lai Chau Province).

Regional extent

Occurs only in Lai Chau Province in two narrow bands, extending from the Vietnam-China boarder through Na Vang to the Ban Mao Village areas.

GeoJSON

null

Fossils

Formas Zellia muongthensis, Pseudofusulina sp., Parafusulina sp., Sphaerulina sp., Geinitzina sp. of Wuchiapingiang age.

Age

Assigned as Middle Permian to Wuchiapingian.

Age Span:

Beginning stage:

Roadian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

274.37

Ending stage:

Wuchiapingian

Fraction up in the ending stage:

0.2

Ending date (Ma):

258.49

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, 2^nd edition; 2011; English edited by A. Boucot).