Yanqiao Fm
(83-85), Capitanian Stage (late Guadalupian Epoch; late-Middle Permian)
Type Locality and Naming
The type section is located in the Yanqiao area about 14 km to the northern suburb of Wuxi City, Jiangsu Province. It was named by Hu Shizhong in 1962, and was issued publicly in 1974.
Lithology and Thickness
Sandstone. It is divisible into three parts: Lower part represents interbeds of dark-grey thick-bedded sandstone and shale, yielding brachiopods, ammonoids, etc. Its basal part consists of Myalina-yielding black calcareous and carbonaceous shales. Middle part is composed of dark-grey fine-grained sandstone, siltstone and shale, containing pyrite and plant fragments. Upper part is composed of grey-green and light-grey sandstones, intercalated with shale, sandy limestones (2-3 layers) and thin coal (layers) seams, yielding abundant Fusulinids, ammonoids, brachiopods, etc., with a thickness of 210 m.
Relationships and Distribution
Lower contact
Upper contact
Conformable contact with its overlying Longtan Fm in the northern part of Jiangsu Province.
Regional extent
Distributed in the areas of Jiangsu, Zhejiang and Anhui Provinces, with a thickness of 60-300 m, and is getting thinner in a direction from NE to SW
GeoJSON
Fossils
In the region of Jiangsu Province the formation yields such fossils as Fusulinids, comprising Metadoliolina lepida, M. ellipsoidalis, M. multivoluta, M. compacta, Codonofusiella wusiana, Schwagerina aff. poctiruga, etc., known as the Metadoliolina-Codonofusiella zone; Ammonoids represented by Shouchangoceras, Altudoceras; and Brachiopods such as Neoplicatifera huangi, Monticulifera sinensis, Tenuichonetes tenuilirata, Urushtoidea sp., etc.
Age
Depositional setting
It is interpreted as a paralic facies (marginal marine)
Additional Information