Xikeng Fm
Type Locality and Naming
It was named by the Jiangxi Party of Regional Geological Survey (1963) and published by the Compiling Group of Regional Stratigraphical Scale of Jiangxi Province in 1980. The type section is located at Xikeng, Sandu, north of the Xiushui County seat in Jiangxi Province. The reference section is at Xiajiaqiao in Wuning County, Jiangxi Province.
Synonym: (西坑组) . Further research would be needed to make sure whether the Yangfujian (Yanghujian) Sandstone is a synonym of the Xiken Fm or a part of the Xiken Fm, or it is another lithostratigraphic unit higher than the Xiken Fm in horizon. (see Additional information for details).
Lithology and Thickness
The formation, about 280 m thick at the type section locality, is composed of purplish red siltstone, pelite and micritic sandstone, often intercalated with yellow green, gray green silty or micritic sandstone.
Relationships and Distribution
Lower contact
It conformably rests on the Xiajiaqiao Fm
Upper contact
It is pseudo-conformably overlain by the Wutong Fm of the Upper Devonian.
Regional extent
The formation, ranging from 10-488 m in exposed thickness, is distributed in north Jiangxi, mainly observed in Wuning and Hukou and not developed in Jiujiang and Ruichang.
GeoJSON
Fossils
The fossils yielded in the formation are rare and belong to near-shore to very shallow-water products, characterized by littoral Agnatha Xiushuiaspis, Sinogaleaspis, Galeaspis as their representative, probably of continental-oceanic amphibian type; in addition, there are allopatric fragments of plant fossils (probably being Prototaxites?).
Age
Depositional setting
Near-shore to very shallow-water
Additional Information
The name Yangfujian (Yanghujian) Sandstone was proposed by Li Yurao (1933). The naming locality is at Yangfujian near Tengyan between Wuning and Ruichang counties (the section on the northern hill at Dongmen, Henlu). It rests on the Yashan Shale; its lower and middle parts consist of 230 m-thick interbeds of sandstone with shale and the upper part is about 80 m-thick brown grit. The solid rock of the Yangfujian Sandstone often makes up 200~300 m-high hills. No fossil evidence was discovered at that time and so it was temporarily assigned to the Silurian. According to the Party of Regional Geological Survey of Jiangxi Province the Yangfujian Sandstone is restricted in Wuning and Ruichang in distribution. Further research would be needed to make sure whether the Yangfujian Sandstone is a synonym of the Xiken Fm or a part of the Xiken Fm, or it is another lithostratigraphic unit higher than the Xiken Fm in horizon.