Chedao Fm
Type Locality and Naming
The type section is at Kushuigou in Nanzhuangzi in Chedao Township, Huanxian County, Gansu. The Chedao Fm was named by Lin Baoyu et al. in 1975, and was published by Gansu Compiling Group for Regional Stratigraphic Scale (1980).
Fei et al. (1983) and Gansu Bureau of Geology and Mineral Resources (1989) lowered the base of the Chedao Fm at the base of the previously defined Nanzhuangzi Fm. An et al. (1990) suggested that the lithology of the Chedao Fm and the underlying Nanzhuangzi Fm are different, and the previously defined Chedao Fm should be maintained.
Synonym: (车道组）
Lithology and Thickness
The formation is dominated by medium-bedded nodular limestone, marl intercalated with limestone, with oolitic limestone and locally psammitic limestone at the top. In the type area, the Chedao Fm is 16.3 m thick.
Relationships and Distribution
Lower contact
It rests conformably on the calcirudite at the top of the Nanzhuangzi Fm
Upper contact
It is unconformably overlain by the Quaternary loess.
GeoJSON
Fossils
Abundant allochthonous cephalopods characterized by Sinoceras chinense, trilobites, crinoid stems and gastropods were found from the limestone in the upper part.
Age
Depositional setting
Additional Information