Anzigou Fm
Type Locality and Naming
It was named by the Gansu Party of Regional Geological Survey in 1975 and published by Zai Yupei in 1977. The type section is at Anzigou in Diebu County, Gansu Province.
Synonym: (安子沟组)
Reference Section:
The reference section is at Baiyigou in Ruoergai County, Sichuan Province.
Lithology and Thickness
The formation, 1490 m in thickness, can be subdivided into 3 parts. Lower part consists of light grey tuff intercalated with black carbonaceous slate; Middle and Upper parts are composed of black carbonaceous slate, phyllite, carbonaceous siliceous slate and chert.
Relationships and Distribution
Lower contact
It contacts conformably with the underlying Ordovician rocks.
Upper contact
It contacts conformably with the overlying Gezi Fm
Regional extent
The lithology is rather steady, but the thickness varies considerably, 730 m thick at Baiyigou, Ruoergai County, 1318 m thick at Tiebuamitang, and 670-750 m at Yangchanggou of Jiangzhang and at Talsai of Zhangwa Town.
GeoJSON
Fossils
It bears graptolites of the Akidograptus zone, the Pristiograptus leei zone, etc.
Age
Depositional setting
Additional Information