Anding Fm
Type Locality and Naming
Ordos Basin. It was named by Wang Zhuquan as the Anding Limestone in 1925. The locality of the naming section is situated in the Anding Township of Zhichang County, Shaanxi Province; with its reference section being located in the area of the Xixingzi River of Yan’an City (Wang Si’en and others, 1985).
Synonym:（安定组）
Lithology and Thickness
Lower part of the formation is composed essentially of grey-yellow, and purple sandstones and mudstones, intercalated with grey-black shales. Upper part consists of grey, purple and grey-yellow lamellated peaty limestones, intercalated with calcareous mudstones, with a thickness of 84 m, and with its Basal part composed of a layer of yellow massive and medium-grained sandstone.
Relationships and Distribution
Lower contact
Upper contact
It contacts conformably with the overlying Fenfanghe Formation in the area of Caobi River at Qianyang.
Regional extent
Ordos Basin. The formation is exposed in the valleys of the Hulu River, Luohe River, Xixingzi River, Qingjian River, Dali River and Wuding River. There are few changes in lithology in various areas, with the thickness varying from 40 m to 128 m. Both to the north and south of the area of its distribution, the formation lithologically changes into red sandstone and mudstone, with marls being missing.
GeoJSON
Fossils
This formation yields Ostracods, such as Darwinula cf. sarytirmenensis, D. sheniensis; Fish fossils as represented by Baleiichthys antingensis; Plant fossils such as Coniopteris sp., as well as spore-pollen fossils.
Age
Depositional setting
Additional Information