Shihuigou Fm
Type Locality and Naming
The type section is at Shihuigou southwest of Dachaidan, Qinghai. The Shihuigou Fm is derived from the Shihuigou Shale proposed by Mu Enzhi et al. in 1958. In 1962, Zhang Wentang renamed the Shihuigou Shale the Shihuigou Fm. Mu (1959) divided the formation into two zones, Amplexograptus confertus zone in the lower part and Pterograptus elegans zone in the upper. In 1976, No.1 Qinghai Party of Regional Geological Survey found graptolite Undulograptus austrodentatus from the lower part.
Synonym: (石灰沟组）
Lithology and Thickness
The Shihuigou Fm is composed of a Lower part of black shale intercalated with calcirudite, and an Upper part of green shale intercalated with sandstone and limestone.
Relationships and Distribution
Lower contact
It rests conformably on the thin-bedded limestone in the upper part of the Duoquanshan Fm
Upper contact
It is unconformably overlain by the Lower Carboniferous. Regionally, it is disconformably overlain by the Datouyanggou Fm of upper Ordovician.
Regional extent
The lithology of the Shihuigou Fm is persistent, but its thickness is variable considerably along the length of its outcrop. At Datouyanggou and Shihuigou in Da Qaidam, it recorded a thickness of 33.4 m and 460 m respectively, and in Oulongbulak, it is 629 m thick.
GeoJSON
Fossils
The graptolite fauna includes Undulograptus austrodentatus zone, Amplexograptus confertus zone and Pterograptus elegans zone, in ascending order.
Age
Depositional setting
Additional Information