Jianchang Fm
Type Locality and Naming
No type section was assigned when the formation was erected by Zhang (1964). An auxiliary section, the Xiaohuanggou section was proposed by Yang and Li (1997) as representative section of the formation (124°29’50”E, 41°15’40”N). The section was measured by the Liaoning Regional Geological Survey Team in 1967 (Nan, 1981; Yang and Li, 1997), and is located near the Xiaohuanggou Gully in the Jianchang Township, Benxi, Liaoning Province, about 2.4 km northeast of Jianchang Town. In the type section, the formation is 119.29 m thick. The Jianchang Formation was named by Zhang (1964). The name is derived from Jianchang Town, Benxi Manchu Autonomous County, Benxi City, eastern Liaoning Province.
Synonym: （碱厂组）
Lithology and Thickness
In the auxiliary section, the Jianchang Formation comprises two parts: Lower part consists of yellowish green shale and dark grey, thin-bedded asphaltic limestone with fine-grained quarrzose sandstone at its base (44.23 m thick). Upper part consists of dark grey, thin-bedded asphaltic limestone, yellowish grey thin-bedded argillaceous limestone, and dark grey, medium- to thick-bedded siliceous limestone bearing chert-nodule or chert-band (75.06 m).
Relationships and Distribution
Lower contact
The Jianchang Fm is in disconformable contact with underlying Qiaotou Fm of Pre-Cambrian in the type area or Cambrian Dalinzi Fm in Dalian area of Liaotung Peninsula. The lower boundary of the Jianchang Fm is defined by the disconformable plane.
Upper contact
It is conformably overlain by the Manto Fm. The upper boundary is defined by the appearance of purple shale at the base of the Manto Fm, which is overlies on the limestone at the top of the Jianchang Fm.
Regional extent
The Jianchang Formation is exposed in the Liaoning-Jilin Area of North China Regions, distributed only in eastern Liaoning province, including the Taizihe River basin and the southern part of Liaotung Peninsula with thickness between 43 and 112 m in the Taizihe River basin, and between 11 and 35 m in the Liaotung Peninsula.
GeoJSON
Fossils
In the auxiliary section, the Jianchang Formation yields trilobites Palaeolenus sp., Redlichia chinensis and R. murakamii from the asphaltic limestone of the lower part, and trilobite Redlichia sp. from the asphaltic limestone of the upper part. In other locality, trilobite Palaeolenus fengyangensis is also recorded from the formation.
Age
Depositional setting
Additional Information