Zhangwan Fm
Type Locality and Naming
It was named by the Institute of Geological Sciences, Henan Province in 1981. The type section is located at Fengjiashan, north of Houaocun Village, Zhangwan Township, Xichuan County, Henan Province.
Synonym: (张湾组)
Lithology and Thickness
It is dominated by yellowish brown and yellowish green claystone, pelitic siltstone, shale and sandstone. It is 261 m thick.
Relationships and Distribution
Lower contact
The formation rests conformably on the Upper Ordovician (Shiyanhe Fm)
Upper contact
It is disconformably overlain by the Baishangou Fm of the Middle Devonian.
Regional extent
It is steady in lithology. The thickness of the formation may increase from the type section locality eastwards up to 500 m.
GeoJSON
Fossils
The formation yields rich graptolite, trilobite, crinoid columnal and minor brachiopod, bryozoa, etc. The graptolite zones can be listed as follows: the Coronograptus leei zone, the Demirastrites triangulates zone, the D. convolutus zone and the Monograptus sedgwickii zone. Trilobites include Encrinuroides meitanensis, Latiproetus latilimbatus, Dicranurus xichuanensis, Leonaspis yunnanensis, Gaotania ovata, etc.
Age
Depositional setting
Additional Information