Dongkengkou Fm
Type Locality and Naming
The type section of the Dongkengkou Formation is located at Dongkengkou Village, about 17 km northwest of the seat of Yong’an City (117°18’E, 26°07’N). The section was measured by Li Jiangai et al in 1980. The Dongkengkou Formation was named by Li et al. (1983). The name is derived from Dongkengkou Village in the Yong’an City (county level), Sanming City, western Fujian Province. Originally it was called Dongkengkou Group by Li et al. (1983), and was subsequently lowered in rank as Dongkengkou Formation by Li J. (1997).
Synonym: （东坑口组）
Lithology and Thickness
The Dongkengkou Formation is a monotonous clastic sequence, consisting of grey and light grey, thick- to mega-thick-bedded, metamorphic carbonaceous sandstone, intercalated with minor greyish, thin-bedded phyllite or phyllitic siltstone. In the type section, the formation is 1198 m thick.
Relationships and Distribution
Lower contact
The Dongkengkou Fm is in conformable contact with the underlying Lintian Fm. The lower boundary of the formation is marked by the disappearance of the greyish, thin- to medium-bedded phyllite of the Lintian Fm.
Upper contact
The Dongkengkou Fm is in conformable contact with the overlying Weifang Fm (Ordovician). The upper boundary is marked by the appearance of light grey or greyish black metamorphic siltstone of the Weifang Fm.
Regional extent
The Dongkengkou Formation is exposed in the Cathaysia Area of South China Region, distributed over western Fujian Province, including Changting, Jianyang, Longyan, Qingliu, Shaowu, Sanming and Yong’an counties or cities. The formation is stable in lithology with thickness varying between 389.8 and 1422.1 m.
GeoJSON
Fossils
The Dongkengkou Formation yields sponge spicule Protospongia sp., micro-paleoplant fossils Archaeohystrichosphaeridium sp., Leiominuscula sp., Leiosphaeridium sp., Polyporata sp., Protoleiosphaeridium sp., Trachyminuscula sp., Trachysphaeridium sp. and Trematosphaeridium sp., and chitinozoans Desmochitina sp., Clavachitina sp., and Conochitina sp.
Age
Depositional setting
Additional Information