Yuejiaping Fm
Type Locality and Naming
The type section is the Yuejiaping section. It lies at side of the highway between Yuejiaping and Wangjiadian villages, 6.5 km west of Xianghe Town, or about 32 km south of the seat of Shangnan County, Shangluo City, southeastern Shaanxi Province. (110°53’26” E, 33°14’50” N). The Yuejiaping Formation was first published by Shaanxi Regional Geological Survey Team (1966a). The name is derived from Yuejiaping Village in Xianghe Township, Shangnan County, Shangluo City, southeastern Shaanxi Province. The name was originally appeared in a 1959 manuscript by the Institute of Geology, Ministry of Geology.
Synonym: （岳家坪组）
Lithology and Thickness
The Yuejiaping Formation is basically a carbonate sequence with interbeds of clastic rocks. The formation is composed of two parts. Lower part consists of light grey to greyish white, thin-bedded to medium-bedded dolomitic limestone, purplish red, reddish grey, and light purple calcareous argillaceous siltstone, with laminated bedding and siliceous bands and lenses or cherty nodules. Upper part consists of purplish red and yellowish grey, fine-crystalline argillaceous dolomitic limestone with laminated bedding, alternated with purplish grey and purplish red calcareous silty shale. In the type section, the Yuejiaping Formation is 164 m thick.
Relationships and Distribution
Lower contact
The Yuejiaping Fm is in conformable contact with the underlying Shuigoukou Fm. The lower boundary is defined by lithological change from thick-bedded dolomite of Shuigoukou Fm to the thin-bedded limestone at the base of Yuejiaping Fm.
Upper contact
The Yuejiaping Fm is in conformable contact with the overlying Shihwengtzu Fm. The upper boundary is marked by the appearance of light grey, thick-bedded dolomite at the base of the Shihwengtzu Fm.
Regional extent
The Yuejiaping Formation is exposed in the Jiangbei Slope Area of South China Region, restricted to southeastern Shaanxi Province (only in the area east of Shanyang Town, Shanyang County, Shangluo City). The thickness of the formation varies from 160 to 231 m.
GeoJSON
Fossils
The basal part of the formation yields trilobites Chittidilla sp. and Kumingaspis sp.
Age
Depositional setting
Additional Information