Quannaogoushan Fm
Type Locality and Naming
The Quannaogou System was named by Wang Shangwen（1950），which includes Angzanggou Series and Laoshangou Series. Yu Changming (1962)revised the Laoshangou Series to Quannaogoushan Series. The Gansu Geological Bureau revised the name to Quannaogoushan Group in 1976, and Quannaogoushan Formation in 1997. The type section is located at Quannaogoushan Mt. in western Hanxia, Gansu Province. Coordinate: 39°49′N、97°08′E.
Synonym: （泉脑沟山组）
Lithology and Thickness
The Quannaogoushan Formation is dominated by gray green, purplish red sandy shale, siltstone intercalated with marl, and limestone. The thickness is 2109 m at the type section.
Relationships and Distribution
Lower contact
The base can be easily distinguished from the graptolite-yielding Angzanggou Fm by the appearance of violet and gray green siltstone. The contact is conformable.
Upper contact
Regional extent
The formation exposed from Hongkouzi of Anxi County to Laojunshan of Mingle County, spreading over 400 km from west to east. The thickness is various from 305-2109 m in different localities. At Hongkouzi of Anxi County, west from Changma the formation is intercalated with many volcanic tuff layers；abundant volcanic rock and volcanic breccia are observed from Anmengou to Baiyanghe River, east of Quannaogoushan Mt.
GeoJSON
Fossils
The formation bears rich anthozoa, such as Multisolenia biformis, M. tortuosa, Mesofavosites gansuensis, Palaeofavosites orientalis, Heliolites abnormis, Nanshanophyllum typicum, N. mirandum; as well as minor brachiopods and trilobites. He Yongji (1983) found some conodonts in two samples at the limestone of this formation. The conodonts were claimed to be the Late Silurian, but neither the photos nor the identification lists were given in his paper.
Age
Depositional setting
The facies of the formation is shallow shelf according to Xu Weidong et al. (2006).
Additional Information