Shang’ouchong Fm
Type Locality and Naming
The type section of the Shang’ouchong Formation is located at Shang’ouchong Village on the north slope of the Langyashan Mountain in Langya District, Chuzhou, Anhui Province (118°17’40”E, 32°15’45”N). The section lies about 7 km southwest of the seat of Langya District and was remeasured by Anhui Regional Geological Survey Team in 1977. In the type section, the Shang’ouchong Formation is 351.92 m thick with Cambrian interval of 108.8 m. The Shang’ouchong Formation was named by Anhui Regional Geological Survey Team (1977). The name is derived from Shang’ouchong Village in Langya District, Chuzhou City, eastern Anhui Province. This formation spans the Cambrian-Ordovician boundary.
Synonym: （上欧冲组）
Lithology and Thickness
The Shang’ouchong Formation is a carbonate sequence. It consists of grey, thick- and mega-thick-bedded limestone, dolomitic limestone or dolomitic limestone bearing siliceous nodules or bands, and siliceous limestone.
Relationships and Distribution
Lower contact
The Shang’ouchong Fm is in conformable contact with the underlying Langyashan Fm. The lower boundary of the formation is hard to be determined as the similar lithology in the boundary interval between the Langyashan and the Shang’ouchong formations. In practice, the base of Shang’ouchong Fm is usually placed at the level of either significant decrease of argillaceous bands or appearance of the limestone bearing siliceous nodules or bands.
Upper contact
The Shang’ouchong Fm is in conformable contact with the overlying Fenhsiang Fm of Lower Ordovician. The upper boundary of Shang’ouchong Fm is defined by lithological change from the limestone to shale at the base of the Fenhsiang Fm.
Regional extent
The Shang’ouchong Formation is exposed in the Jiangbei Slope Area of South China Region, restricted in eastern Anhui Province (Chuxian and Quanjia). The formation’s thickness of 352 m is known only from the type section.
GeoJSON
Fossils
The type section yields cephalopods such as Chuxianoceras, Dellacaelomoceras, Kirkoceras and Oderoceras etc.; brachiopods such as Archaeorthis, Imbricatia and Nanorthis. As reported by Li and Jiang (1997), the formation yields also conodonts Cordylodus intermedius, C. angulatus, Scolopodus bassleri, and S. triplicates.
Age
Depositional setting
Additional Information