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Suoi Phat Formation

Suoi Phat Fm

Period: 
Paleogene

Age Interval: 
Oligocene, (9)


Province: 
West Bac Bo

Type Locality and Naming

Reference section (Vu Khuc, Pham Dinh Truong and Le Thanh Huu (2002) is well-exposed in the Sai Luong area (Yen Chau district, Son La Province), on the new car road extending along the side of Suoi Phat Stream from Chieng Chan Commune to Ta Chan Village.

Synonym: Nam Un Fm (used by Tong-Dzuy Thanh and Vu Khuc (Editors; Stratigraphic Units of Viet Nam; 2011), but Suoi Phat Fm as used by Tran Van Tri and Vu Khuc (Editors; Geology and Earth Resources of Viet Nam, 2011) is used in this Lexicon entry. - Diệp Nậm ủn: Đỗ Văn Hàn etal. 1981 (Upper Tríassic). - Hệ tầng Suối Phái: Vũ Khúc, Phạm Đình Trưởng, Lê Thanh Hựu 2002. - Hệ tầng Sài Lương: Lê Thanh Hựu, Vũ Xuân Lực 2004 (Oligocen)


Lithology and Thickness

Lacustrine beds containing oil shale. Reference section (total of 100 m): (1) Yellowish-grey pebble- and gravel-bearing gritstone with some interbeds of coarse sandstone, 4-5 m thick. (2) Black-grey siltstone and clay shale containing much plant humus emittting a petroliferous odor, interbedded with yellowish gritstone and sandstone, 64 m thick. (3) Grey siltstone and claystone, with yellowish-grey sandstone, 30 m thick.


Lithology Pattern: 
Siltstone


Relationships and Distribution

Lower contact

Rests unconformably upon Paleo-Mesozoic bedrocks (e.g., Yen Chau Fm or Nam Po Fm).

Upper contact

Not given.

Regional extent

Local exposures in Song La Province (Yen Chau district).


GeoJSON

null

Fossils

Oil shale exposed near Sai Luong Viilage yielded leaf impressions of Laurus cf. similis, Arundo sp., Graminiphyllum sp., Phragmites sp., Ficus sp, of Oligocene age. Spores and pollen are also found.


Age 

Oligocene according to the paleontology. [For graphic purposes to show the Oligocene Hong Mon Fm coal-bearing sequence in the same Yen Chau Valley of Son La Province, drawn here slightly lower.]

Age Span: 

    Beginning stage: 
Rupelian

    Fraction up in beginning stage: 
0.0

    Beginning date (Ma): 
33.90

    Ending stage: 
Rupelian

    Fraction up in the ending stage: 
1.0

    Ending date (Ma):  
27.29

Depositional setting

Lacustrine beds containing oil shale


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).