Pochengzi Fm
Type Locality and Naming
Eastern South Tianshan. The type section is located at Kalatage, Keziletage, south of Tuokexun County, Xinjiang. It was named by Xinjiang No 2 Team of Regional Geological Survey in 1958, and was published by “The Regional Scale of Northwest China-Xinjiang” in 1981.
Lithology and Thickness
Volcanics. Quartz porphyry tuffaceous lava. The Pochengzi Fm in the Xinger area includes three subformations:
Lower subformation is composed of quartz porphyry tuffaceous lava, tuffaceous sandstone, agglomeratic tuffaceous lava, sandstone, siltstone and limestone, 600-800 m thick.
Middle subformation is composed of tuffaceous sandstone intercalated with tuffaceous lava, tuffaceous conglomerate and limestone, 500-700 m thick.
Upper subformation is composed of quartz porphyry, quartz porphyry tuffaceous lava, tuffaceous conglomerate and tuffaceous sandstone intercalated with a few limestone lenses, 363 to 1120 m thick.
Relationships and Distribution
Lower contact
The Pochengzi Fm conformably overlies on middle Devonian.
Upper contact
It has an unconformable upper contact to the overlying Gancaohu Fm of Lower Carboniferous.
Regional extent
GeoJSON
Fossils
Middle subformation yields brachiopoda Yunnanella, Atrypa, Schuchertella etc.
Upper subformation yields brachiopod Cyrtospirifer, Camarotoechia.
Age
Depositional setting
Additional Information