Shiguan Fm
Type Locality and Naming
The type section is located in the Shiguan area to the southwest of the Zhangxian County, Gansu Province; its reference section is situated in between the region from the Shiquan Village to the Xiematai Village of the Dacaotan Country, Zhangxian County. It was named by Huang Zhenhui in 1959, when he was attending an On-the-Spot Meeting on the Lanzhou Stratigraphy and lecturing at the meeting on "The Stratigraphy of the Palaeozoic Era in the Western Segment of Qinling Mt." during All-China Conference on Stratigraphy.
Lithology and Thickness
Limestone. Composed of grey and purple thin- and thick-bedded bioclastic limestone, marl, oolitic limestone and clayey siltstone. The thickness ranges from 300 to over 1430 m.
Relationships and Distribution
Lower contact
Uncertain; no distinct contact relationship with underlying strata due to its being dissected by faults. Regional stratigraphy column indicates next older unit is Dieshan Fm.
Upper contact
Uncertain; no distinct contact relationship with overlying strata due to its being dissected by faults. Regional stratigraphy column indicates next younger unit is Lower Triassic.
Regional extent
From the Shiguan Village eastward to the area of the Xinshizheng Township, the amount of clastic substance in the Shiguan Fm is increasing, and the strata are getting thinner to be gradually thinning out to disappear completely. The formation is 229-m thick at Likaru of the Luqu County, 470-m thick at Buchala of the Balie County, over 300-m thick in the area of Lintan and Zhangxian Counties, and over 1430-m thick in the Dongzakou area. In the Huangjiashigou area of the Taian County the formation is composed of grey-green fine-grained sandstone, clayey siltstone and carbonaceous shale, with its base being intercalated with coal seams, with a thickness of over 100 m
GeoJSON
Fossils
Brachiopods are predominant, with the less abundant Fusulinids represented by the PalaeoFusulinida, corals and ammonoids, etc.
Age
Depositional setting
It is interpreted as open-platform facies, marginal shallow-beach-facies and restricted platform-facies deposits.
Additional Information