Muong Trai Fm
Type Locality and Naming
Song Da – Tue Le Basin. The type section is located along the Muong Trai and Ban He streams, near Muong Trai Village, Thuan Chau District, Son La Province (N= 21° 32'; E= 103° 42’).
Synonym: Hệ tầng Mường Trai'. Trần Đăng Tuyết (in Phan Cự Tiến et al.) 1977; Trần Đăng Tuyết et al. 1978; Bùi Phú Mỹ et al. 1978; Nguyễn Vĩnh et al. 1978; Vũ Khúc 2000, {in VQ Khúc et al.) 2000. - Diệp M ường Trai: Vù Khúc, Bùi Phú Mỹ et al. 1990; Vù Khúc 1989, 1990. - ỉlệ tầng Bản Tang (part.): Dovjikov A.E. et al. 1965; Vũ Khúc 1965. - Điệp Sin Cao: Bùi Phú Mỹ, Vũ Khúc, Trịnh Thọ (in Trẩn Văn Tri et al. 1977); Vũ Khúc, Trịnh Thọ (in Dương Xuân Háo et al. 1980); Vũ Khúc 1984.
Lithology and Thickness
Siltstone, Marl, Limestone and Volcanics: Stratotype: (1) Tuffaceous sandstone, greenish-gray laminated mafic amygdaloidal volcanics, nearly 100 m thick; (2) Black-grey thick-bedded marl, 400-450 m thick; (3) Black-grey thin-bedded claystone and siltstone, 200-250 m thick; (4) Grey to black-grey, thin- to medium-bedded limestone interbedded with dirty-yellow crusted limestone, 300 m thick; (5) Grey siltstone, sandstone interbedded with dark grey claystone, tuffs and some interbeds of black-grey mafic volcanics, 600-700 m thick. The total thickness is about 1600-1800 m.
Relationships and Distribution
Lower contact
Conformably underlain by the Nam Tham Fm
Upper contact
Conformity beneath the Carnian shale of the Nam Mu Fm
Regional extent
It occurs in narrow bands in the Tam Duong area extending through Sin Cao to Than Uycn (Lai Chau Province), in the Muong Trai, Nam Mu areas, and along the Song Da River, from Quynh Nhai to near Van Yen Townlet (Son La Province)
GeoJSON
Fossils
A nearshore assemblage known in North Viet Nam as the Costatoria-Trigonodus Assemblage and the deepwater assemblage known as the Daonella-Posidonia Assemblage. Costatoria goldfussi, C. multicostata, Trigonodus sandbergeri, T. tonkinensis trapezoidalis, and Cassianella gryphaeata.
Age
Depositional setting
Additional Information