Jingyuan Fm
Type Locality and Naming
The type section is located at Yushuliang-Hongtuwa, about 20 km northeast of Jingyuan, Gansu. It was named by Li Xingxue et al. in 1974.
Lithology and Thickness
Sandstone and Claystone. Composed of gray, black and yellow sandstones and shales, intercalated with gray-white sandy conglomerate and coal streaks, 50 m thick, and intercalated with limestone lenses in the lower part.
Relationships and Distribution
Lower contact
Disconformable contact with the underlying Chouniugou Fm
Upper contact
Conformable contact with the overlying Hongtuwa Fm
Regional extent
The formation spreads out at the north slope of the Qilian Mts. and east segment of the Hexi Corridor.
GeoJSON
Fossils
Contains over 20 species of 11 genera of Ammonoids, including Eumorphoceras bisulcatum, Cravenoceras shimanskyi, Verancoceras tabidum, etc.; conodont Gnathodus bilineatus bollandensis of early Namurian Age (zone E). The shales underneath limestone lenses yield Plants Neuropteris gigantea, Linopteris neuropteroides, etc. as well as spores Tripartites trilinguis, Simozonotriletes arcuatus, etc., corresponding to the subzone E1 classified on Goniatitida; those over limestone lenses yield plants Sphenophyllum tenerrimum, Eleutherophyllum waldenburgense, etc., and spores Simozonotriletes verrucus-Stenozonotriletes rotundus, etc., corresponding to the subzone E2 of Western Europe. Spores in the middle and lower members of the original Jingyuan Fm are divided into 3 zones, which are ascending: the (1) Reticulatisporites carnosus-Savitrisporites nux, (2) Bellispores nitidus-Rotaspora knoxi, and (3) Crassispora kosankei-Grumousisporites varioreticulatus zones.
Age
Depositional setting
It is interpreted as neritic, locally with littoral-limnetic deposits.
Additional Information