Jiannigou Fm
Type Locality and Naming
It was proposed by Zhai Yupei in 1975. The type section is at Jiannigou of Diebu County, Gansu Province.
Synonym: (尖尼沟组)
Lithology and Thickness
The formation, 71 m thick, consists of gray, dark gray and black sandy carbonaceous phyllite intercalated with siliceous slate and chert, and is steady in lithology.
Relationships and Distribution
Lower contact
The Jiannigou Fm conformably contacts onto the underlying Gezi Fm
Upper contact
The Jiannigou Fm conformably contacts with the overlying Xiaolianggou Fm
Regional extent
It is poorly exposed at the type section locality. It is 231 m thick at the Nanshimengou section in Zhouqu County, Gansu Province, and is 528 m thick at the Xiaolianggou section where it is intercalated with limestone.
GeoJSON
Fossils
It yields rich graptolite, the main elements namely being: Oktavites spiralis, Monograptus priodon, Monoclimacis cf. vomerina, Retiograptus geinitzianus, Pristiograptus sp. etc.
Age
Depositional setting
Additional Information