Sandaokan Fm
Type Locality and Naming
The type section is at Sandaokan on the northern slope of the Gangder Hill in Wuhai City, Inner Mongolia. The reference section is at Dongshan in Laoshidan in Wuhai City (An et al., 1990). The Sandaokan Fm is derived from the Sandaokan Bed proposed by Guan Shichong and Che Shuzheng in 1953. The Sandaokan Bed was published first by Guan Shichong and Che Shuzheng in 1955, and was renamed the Sandaokan Fm by Lu Yanhao in 1954.
Synonym: (δΈιεη»)
Lithology and Thickness
The Formation is dominated by interbedded light gray quartz sandstone, grayish white dolomitic limestone and limestone of saline or semi-saline sea setting, with several bioclastic limestone beds in the lower-middle part. In the type area, the Sandaokan Fm is 90 m thick.
Relationships and Distribution
Lower contact
It rests disconformably on the limestone of the Gushan Fm (not in Lexicon entries); the Hulusitai Fm of upper Cambrian is the next older regional unit.
Upper contact
It is conformably overlain by the limestone of the Zhuozishan Fm.
Regional extent
The Sandaokan Fm, with a persistent lithology, is 40-90 m thick, and is mainly exposed on Qianli Hill, Wuhu Hill, Qipanjing, Lasengmiao, Gangder Hill and Zhuozi Mountain east of Wuhai City. From the drilling data, several meters to several ten meters of equivalent strata have been found at Hengshanbao in Lingwu County, Ningxia (Ningxia Bureau of Geology and Mineral Resources, 1990).
GeoJSON
Fossils
This stratigraphic unit yields cephalopods of Pseudowut inoceras assemblage and Parakogenoceras assemblage, conodonts of Aurilobodus leptosomatus-Loxodus dissectus assemblage, and is equivalent to the Oepikodus evae zone.
Age
Depositional setting
Saline or semi-saline sea setting
Additional Information