Yen Binh Fm
Type Locality and Naming
Triassic sediments in the Paleozoic Song Lo Structure. The type section is located on the dirt road from Kim Cang to Kim villages, Yen Binh Commune, Bac Quang District, Ha Giang Province (N = 22°23’; E = 104°35’). It was named by Lưu Hữu Hùng et al. 2000.
Synonym: Hệ tầng Yên Binh: Lưu Hữu Hùng et al. 2000; Vũ Khúc (in Vũ Khúc et al. 2000). Trias trung-thượng (part.): Vasilcvskaia E.D. (in Dovjikov A.E. et al. 1965); Diệp Sông Hiến (part.): Trịnh Thọ (in Trần Văn Trị et al. 1977); Nguyễn Kinh Quốc (in Vũ Khúc. Bùi Phú Mỹ et al. 1990).
Lithology and Thickness
Conglomerate and Sandstone: (1). Conglomerate, light grey, mcdium-beddcd sandstone with some intcrbeds of grey siltstonc, 20 m thick. (2). Grey, yellowish-grey weathering, thin-bedded siltstone, 40 m thick. (3). Medium-bedded sandstone interbedded with grey siltstonc and some conglomerate, 230 m thick. The total thickness of the formation rcaches about 290 m.
Relationships and Distribution
Lower contact
Unconformably by red beds of the Ban Hang Fm.
Upper contact
Unconformably with basal conglomerate upon the lower Triassic Hong Ngai Fm (Ha Giang Province exposures) or Chung Pung Fm limestone of lower Paleozoic (Yen Bai Province exposures)
Regional extent
Yen Binh Fm has a very limited distribution area in two small areas: Yen Binh area (Yen Bai Province) and Pho Bang area (Ha Giang Province).
GeoJSON
Fossils
Acrochordiceras cf. fischeri. Margarites sp. The collection of ammonoids not entirely similar to that of any Anisian formation of the adjacent area, therefore the describcd sediments are worth describing as an independent formation.
Age
Depositional setting
It is interpreted as near-shore facies.
Additional Information