Xiyaergang Fm
Type Locality and Naming
Qinghai Tibet Plateau Geological Survey Team of the Ministry of Geology and Mineral Resources named in 1983 and first quoted by Wu Ruizhong et al. in 1985. The named section is located in the Xiyaergang Snow Mountain, south west of Shuanghu County, Tibet. It was discovered in 1987 by Rao Rongbiao et al. that the Late Triassic strata in Shuanghu County consist of marine sediments in the lower part and marine, terrestrial interactive sediments in the upper part.
Lithology and Thickness
Mainly black and dark gray microcrystalline limestone, and yellow gray, gray, gray green sandstone limestone, gravel limestone, oncolitic limestone and sandy mudstone constitute unequal thickness interbeds. Thickness is 639 m.
Relationships and Distribution
Lower contact
The bottom boundary of this formation is marked by the occurrence of the intraclast limestone, which is conformable contact with the underlying Dongbula Fm
Upper contact
The top boundary is marked by a disconformable surface to the overlying middle and Upper Jurassic. [maybe implies the Sewa Fm ??]
Regional extent
This formation distributed in the area of Shuanghu County, Northern Tibet. In addition to the named site Xiyaergang Snow Mountain, it is also distributed in the south wing of the Dongbula Anticline. Thickness is 800-1200 m except for named site.
GeoJSON
Fossils
There are abundant fossils of bivalves and brachiopods. The more important representatives are the ammonoids: Tropites cf. subbullatus, Arietoceltites cf. itoides, Discotropites sp., etc.
Age
Depositional setting
This formation is a shallow water deposit
Additional Information