Ganxi Fm
Type Locality and Naming
The type section is located along the bank of Pingtong River, southeast of Ganxi Township in Beichuan County, Sichuan Province. It was named by Bao Ci, Peng Kaiqi et al. in 1955, and Yue Senxun quoted formally in 1956.
Lithology and Thickness
Siltstone. The formation is composed of silty mudstone, clayey siltstone intercalated with bioclastic limestone. In Pingyipu area, the lithology is regionally stable and the thickness commonly varies between 150-250 m. It is 195 m thick.
Relationships and Distribution
Lower contact
It has a conformable contact with the underlying Bailiuping Fm.
Upper contact
It has a conformable contact with the overlying Xiejiawan Fm.
Regional extent
GeoJSON
Fossils
It contains abundant benthos fossils, mainly brachiopods, corals, trilobites, bivalve, ostracods and a few pelagic conodonts and tentaculites. There are two brachiopod assemblage zones: the “Howittia” opiparus-Parathyrisina-Neoathyrisina typica assemblage zone in the lower part and the Dicoelostrophia punctata-Rostrospirifer tonkinensis assemblage zone in the upper part; there is also the conodont dehiscens zone.
Age
Depositional setting
The deposits can be divided into mixed tidal flat, bioclastic beach, back-beach flat and shallow shelf facies.
Additional Information