Wenbishan Fm
(91-93), mid-Guadalupian Epoch (mid-Middle Permian)
Type Locality and Naming
The type section is located at the Wenbi Mt. to the east of the Grand Lake 10 km to the west of Yongan City Town, Fujian Province. The reference section is situated in the Subang area of the Yanshi Country 30 km to the north by east of Longyan City Town.It was named by Gao Zhenxi in 1947.
Lithology and Thickness
Siltstone. Representing a suite of grey siltstone and siltstone, intercalated locally with fine-grained sandstone, containing commonly phosphorus and ferruginous concretions. Lower part is composed of dark-grey thin-bedded silty shale, yielding ammonoids and bivalves. Middle part is composed of purple siltstone, intercalated with fine-grained sandstone, yielding plant fossils (phytolites). Its basal part consists of dark-grey and purple siltstones. Upper part is composed of purple thin-bedded siltstone, yielding bivalves, brachiopods and ammonoids. Both the upper and lower parts contain phosphorus and ferruginous concretions. Thickness range is 71-347 m
Relationships and Distribution
Lower contact
Conformable contact with the limestone of the underlying Qixia Fm
Upper contact
Conformable contact with the grey medium-bedded fine-grained quartz-sandstone of the overlying Tongziyan (Tungtseyan) Fm
Regional extent
The formation is characterized by a stable lithology, and is distributed in Fujian and Guangdong Provinces. In the area of Longyan City and the Madongan area of the Yongding County of Fujian Province the thickness of the formation is of over 320 m, and is of 347 m in the Luofang area of the Liancheng County. In the Jiaoling area of Guangdong Province the thickness of the formation is of 227 m. In the region of an alignment extending from Longyan City of Fujian Province to the Jiaoling area of Guangdong Province the thickness of the formation is getting smaller to both its eastern and western flanks, meanwhile the grain size of the rocks is getting finer.
GeoJSON
Fossils
Yields Ammonoids such as Altudoceras, Shouchangoceras, Paraceltites, Waagenoceras, Mexigoceras, Kufengoceras, Paragastrioceras, etc.; and Brachiopods represented by the Haydenella chinensis-Dictyoclostoidea kiangsiensis assemblage, , belonging to the Kufengian Stage.
Age
Depositional setting
It is interpreted as a suite of platform basin-marginal-facies clastic-rock deposits.
Additional Information