Shuangjianshan Fm
Type Locality and Naming
The type section of the Shuangjianshan Formation is located at Shuangjianshan, about 10 km northeast of the Songhe Town, Jingshan County, Hubei Province (113°20’30”E, 31°16’05”N). It was measured by Hubei Regional Geological Survey Team in 1980. The Shuangjianshan Formation was named by Hubei Regional Geological Survey Team (1982). The name is derived from Shuangjianshan Hill in Songhe Township, Jingshan County, Jingmen City, central Hubei Province.
Synonym: （双尖山组）
Lithology and Thickness
The Shuangjianshan Formation is a carbonate sequence. In the type section, the formation is divided into three parts: Lower part, 79.96 m thick, consists of grey and dark grey limestone, intercalated with thin-bedded argillaceous limestone and with greyish black, thin- to medium-bedded argillaceous chert at its basal part; Middle part, 47.89 m thick, consists of grey and greyish white, thin- to medium-bedded carbonaceous and dolomitic striped limestone and dolomitic limestone; Upper part, 69.42 m thick, consists of greyish yellow and yellow, thin- to medium-bedded argillaceous and siliceous limestone, intercalated with lenticular microcrystalline limestone and argillaceous and dolomitic siltstone. In the type section, the Shuangjianshan Formation is 197.27 m thick.
Relationships and Distribution
Lower contact
The Shuangjianshan Fm is in conformable contact with the underlying Yanwugou Fm. The lower boundary of the formation is marked by lithological change from the black shale at the top of Yanwugou Fm to the limestone at the base of Shuangjianshan Fm.
Upper contact
The Shuangjianshan Fm is in conformable contact with the overlying Liqiuwan Fm. The upper boundary is by lithological change from the limestone of Shuangjianshan Fm to the slate of Liqiuwan Fm.
Regional extent
The Shuangjianshan Formation is exposed in the Jiangbei Slope Area of South China Region, distributed in northern Hubei Province (Jingsha, Anlu and Suixian counties). The thickness of the formation varies from 24 to 197 m.
GeoJSON
Fossils
No fossil was reported from the formation yet.
Age
Depositional setting
Additional Information