Qushai Fm
Type Locality and Naming
It was named by the Regional Geological Survey Party of the Tibetan Bureau of Geology and Mineral Resources in 1986. The naming section is located at the Hot Spring of Suobuca, Shaiwa Region, Bange County, Tibet, with its reference section being located in the Zesong area, Shaiwa Region, Bange County, Tibet.
Synonym: （曲色组）
Lithology and Thickness
Lower part represents light-grey mudstones, intercalated with marls, calcareous sandstones and shales, as well as grey and dark-grey medium-, and thick-bedded siliceous limestones, intercalated with thick-bedded microcrystalline limestones. Middle part represents grey-black medium-, and thin-bedded, thick-bedded and massive limestones. Upper part represents grey phyllitic marls, intercalated with thin-bedded gritstones and quartz-sandstones, with a thickness of over 955 m.
Relationships and Distribution
Lower contact
Its basal part with a layer of siliceous limestones is in a conformable contact with the medium-, and thick-bedded microcrystalline limestones from the underlying upper Triassic Xiaorongka Gr (= probably the Xiaochaka Gr of same location/age in Xiaorongka region)
Upper contact
No top part having been found. In the Zesong section of the Shaiwa region, the formation is in a conformable contact with the overlying middle Jurassic Shaiwa Fm (= Sewa Fm )
Regional extent
The formation is exposed only in the areas of Qushai, Zesong, Barza and the hot spring of Suobuca in the vicinity of the Shaiwa region, with a consistent lithology, and a thickness of over 955-1732 m.
GeoJSON
Fossils
In the area of Qushai it yields ammonites as represented by Pelyplectus sp., Lytoceras cf. fimbriatum, Ptycharielites sp., Schlotheimiidae, Arietitidae. In the Zesong area of Shaiwa region it yields such ammonites as Psilocerataceae, Oxynoticeratidae? Lioceratoides sp., Tiltoniceras sp., Maconiceras sp., Eleganticeras sp. and Hildaites sp.
Age
Depositional setting
Additional Information