Beiguoshan Fm
Type Locality and Naming
The type section is on the Beiguo Hill in Lijiapo of Longxian, Shaanxi. The Beiguoshan Fm was derived from Fu Lipu's Beiguoshan Limestone proposed in 1977.
Che Fuxin (1963) first reported the Upper Ordovician limestone overlying the Pingliang Shale exposed on the Beiguo Hill in Lijiapo of Longxian, Shaanxi, and described the lithology, distribution, fauna and their geological significance. However, he didn't gave a name for the stratigraphic unit. Fu (1977) measured the section, and named the limestone the Beiguo Limestone, which was renamed the Beiguoshan Fm by Shaanxi Compiling Group for Regional Stratigraphic Scale (1979).
Synonym: (背锅山组）
Lithology and Thickness
The formation is dominated by thick-bedded, massive and medium-bedded limestone with nodular limestone and thin-bedded limestone at the base. In the type area, the Beiguoshan Fm records a thickness of 125-325 m.
Relationships and Distribution
Lower contact
This formation rests conformably on the thin-bedded limestone and shale of the Pingliang Fm
Upper contact
An upper boundary disturbed by fault.
Regional extent
The Beiguoshan Fm, with a persistent lithology, is exposed in Longxian of Shaanxi and Shijiezigou in Luowa of Pengyang County (former Guyuan County), Ningxia.
GeoJSON
Fossils
This stratigraphic unit yields corals Agetolites, Plasmoporella and Catenipora; brachiopods Schizophoria, Eospirigerina, Ovalospira and Rhynchotrema; trilobite, conodonts of Yaoxianognathus yaoxianensis-Belodina confluens assemblage (An et al., 1990).
Age
Depositional setting
Additional Information