Yangmaba Fm
Type Locality and Naming
The type section is located at Kumaliu of Yangmaba Village, Jiangyou County of Sichuan Province. It was named by Zhu Seng in 1942.
Lithology and Thickness
Calcareous Sandstone and Limestone. The Formation, 128 m thick, is characterized by a lower part of gray calcareous sandstone and bioclastic limestone with sandy shale and limestone, and upper part of Zdimir brachiopod bearing bioclastic limestone.
Relationships and Distribution
Lower contact
It overlies the massive limestone of the Ertaizi Fm as a conformable contact or as transgressive deposit onto a former exposed surface of that Ertaizi Fm.
Upper contact
It is overlain by the sand-silt facies of the Jinbaoshi Fm.
Regional extent
GeoJSON
Fossils
Conodont Polygnathus serotinus Zone.
It contains four Brachiopod assemblage zones, in ascending order:
Xenospirifer nitidus-Athyrisina obesa Zone, Otospirifer sichuanensis-Luanquella striatula Zone, Neocoelia sinensis-Chuanostrophia scirtula Zone and Zdimir Acme Zone;
three Coral assemblage zones, in ascending order: Zonophyllum beichuanense-Calceola gangxiense Zone, Cyathophyllum sichuanense-Haplothecia flata Zone and Utaraturia sinensis Zone
Age
Depositional setting
Hybrid carbonate-siliciclastic shelf, with frequent storm beds (Fengjie Li et al., in press, GSA Bull., 2021)
Additional Information