Bairabco Fm
Type Locality and Naming
It was named by the Regional Survey Party under the Tibetan Geological Bureau in 1987. The naming section is located on the northwestern bank of the Bairab Co northeast of the Doma District, Ritu County, Tibet (E 82°55′, N 35°04′).
Synonym: （拜惹布错组）
Lithology and Thickness
It is composed of grey and purple thin-bedded medium-grained sandstone, calcareous sandstone and siltstone, with a thickness of over 172.8 m.
Relationships and Distribution
Lower contact
No base has been found. Regionally, it is in a conformable contact with the original underlying "lower part" of the Yanshiping Gr.
Upper contact
Its top part is in a conformable contact with the grey-yellow medium-, and thick-bedded limestone and argillaceous limestone at the base of the overlying uppermost Yanshiping Gr (Danshuihe Fm?)
Regional extent
The formation is exposed sporadically along the southern side of the Longmu Co-Bairab Co Deep Fracture Zone. It represents deposits in the area of the local depression zone on the northern margin of the Qangtang Massif.
GeoJSON
Fossils
In the area on the northwestern side of the Bairab Co there are found Ammonites Coroniceras sp. in the formation, while in the northeastern part of the Bairab Co the formation yields Gastropod: Psuedomalania cf. kouzenetsovi, and bivalves: Cossmannella sp.
Age
Depositional setting
It represents deposits formed at the early stage of marine transgression during the Jurassic Period in the area of the local depression zone on the northern margin of the Qangtang Massif.
Additional Information