Jishi Fm
Type Locality and Naming
The type section is located near the Jishi County. It was named by Li et al. (1995). The Jishi conglomerate was regarded as the base conglomerate of the Lower Pleistocene sub-clay, i.e., the Wucheng Loess, by the First Regional Geologic Survey Team of the Gansu Geological Bureau (1965).
Lithology and Thickness
The Jishi Fm consists of grey and partially carbonated coarse conglomerates (up to 20 cm) having massive bedding or roughly imbricated structure and many intercalated lenses of siltstones and mudstones. Gravels at the lower part have clear imbricate structure.
Relationships and Distribution
Lower contact
The Jishi Fm is in unconformable contact with the under- and overlying strata.
Upper contact
The Jishi Fm is in unconformable contact with the under- and overlying strata.
Regional extent
The thickness of the Jishi Fm varies greatly. It has been eroded away in the Maogou section; the thickness in the Wangjiashan section is about 30 m, and the thickness near the Jishi County area is more than 60 m.
GeoJSON
Fossils
No any mammal fossil is found from this formation.
Age
Depositional setting
It is interpreted as mountain rivers, debris flow deposition
Additional Information