Chenjiawan Fm
Type Locality and Naming
It was named by Zhang Zhenlai and Meng Fansong in 1987. The naming section is located at Chenjiawan in the vicinity of Xietan area of Zigui County, Hubei Province.
Synonym: （陈家湾组）
Lithology and Thickness
Composed essentially of purple, yellow-green mudstone, sandy mudstone and siltstone, intercalated with yellow-grey and grey-green medium-, and fine-grained feldspar-quartz sandstone, intercalated occasionally with marl bands, and with a total thickness of 766 m.
Relationships and Distribution
Lower contact
Upper contact
Regionally, the schematic strat column indicates the next younger unit as Suining Fm; however Suining Fm is usually restricted to Sichuan Basin; therefore, in this Jingmen-Dangyang Basin, the next younger formation may be the Shimen Fm of mid-Cretaceous?
Regional extent
The formation is distributed essentially in Zigui area, and the Jingmen-Dangyang Basin. In the area from the Xietan region of Zigui County to the Badong region it is 760-m thick, while in the Pingyi area of Xingshan County, it is 470-m thick. In the Jingmen-Dangyang Basin this formation is exposed incompletely and is characterized by changes in both its thickness and lithology. For example, at Baishi Port, Dangyang County to Bajinpuo, the formation is composed largely of yellow-grey feldspar-quartz sandstone, siltstone and sandy mudstone, intercalated locally with purple mudstone. At the base of the formation there occurs a layer of yellow pebble-bearing coarse-grained sandstone serving as a boundary between it and the Xietan Fm, and being of about 430 m in thickness.
GeoJSON
Fossils
It yields bivalves as represented by the Lamprotula (Eolamprotula) cremeri-Pseudocardinia kweichouensis assemblage. Of the plant fossils there occur only Neocalamites sp., Cladophlebis sp. and Taeniopteris cf. parvula.
Age
Depositional setting
The formation belongs to fluvial and lacustrine deposits.
Additional Information