Quesangwenquan Fm
Type Locality and Naming
It was named by Wang Naiwen in 1983. The naming section is located at the Quesang Hot Spring 54 km north of Lhasa City, Tibet.
Synonym: （却桑温泉组）
Lithology and Thickness
Lower part is composed of grey and grey-brown conglomerates, sandy conglomerates, medium-, and thick-bedded feldspar-quartz sandstones, intercalated with siltstones and shales. Upper part has alternating layers of grey calcareous shales and silty shales together with the grey-brown medium-, and thick-bedded sandstones. It is 500 m in thickness.
Relationships and Distribution
Lower contact
Its basal part with its grey and grey-brown conglomerates and sandy conglomerates is in an unconformable contact with the andesite intercalated with limestones from the underlying lower and middle Triassic Danbarizi Gr. (not in Triassic Lexicon; but a Mailonggang Gr is indicated as the next older regional unit of upper Triassic that has an upper volcanic tuff). Regionally, its basal part is always in an unconformable contact with the underlying strata.
Upper contact
Its top part is in a conformable contact with the limestones from the overlying Duodigou Fm.
Regional extent
The formation is distributed largely in the region of Lhasa City with a consistent lithology.
GeoJSON
Fossils
It yields bivalve fossils such as Astartoides dingriensis, A. gambaensis, Protocardia sp., Ostrea sp. and Anisocardia sp.; and Gastropod fossils as represented by Pleurotomaria spitiensis. Its basal part yields plant fossils as represented by Ptilophyllum sp. and Zamites sp.
Age
Depositional setting
Additional Information