Yungang Fm
Type Locality and Naming
It was named by Morita N. as the Yungang Series in 1944, and was first cited publicly by Li Xingxue in 1955. The naming locality is situated at Yungang Town of Datong City, Shanxi Province (Morita N., 1944, A Study on the Datong Coalfield, unpublished).
Synonym: （云岗组）
Lithology and Thickness
Lower member (the Qingciyao Member) is composed of grey-white and grey-yellow sandstones, intercalated with a small amount of purple mudstones, with a thickness of 60-250 m. Upper member (the Shiyao Member) is composed of yellow-grey, dark-purple and grey-green sandstones and mudstones, with a thickness of 100-212 m.
Relationships and Distribution
Lower contact
It is in a disconformable contact with the underlying Datong Fm
Upper contact
It is in a conformable contact with the overlying Tianchihe Fm
Regional extent
The formation is distributed in a large scale in the Jingle Basin of Ningwu County as well, in addition to that which is distributed in the Yungang Basin of Datong City. Also, there are scattered exposures of the formation found to occur in the northern part of the Xinshui Basin. There are some variations in its thickness in various regions, being thicker on the south and thinner on the north. For instance, in the Datong coalfield it is about 250 m thick, while in the Ningwu Coalfield it is about 400 m thick in the Ningwu Coalfield, as far as till the area of Guxiang County its thickness is of 750 m.
GeoJSON
Fossils
It yields plant fossils as represented by the Coniopteris-Phoenicopsis flora. In addition, it yields also bivalve fossils as represented by Ferganoconcha curta, F. subcentralis, F. heifengensis and Margaritifera isfarensis, as well as “conchostracan” fossils as represented by Euestheria datongensis.
Age
Depositional setting
Additional Information