Jingchuan Fm
Type Locality and Naming
Ordos Basin. Zhang Geng and Tian Zaiyi et al erected the Jingchuan bed in 1952. The section for the designation is near the Jingchuan County of Gansu. The reference section is from Jingchuan of Gansu to Jujiawan of Binxian of Shaanxi (107°22′E; 35°20′N). An upper formation in Zhidan Gr.
Lithology and Thickness
The Jingchuan Formation is represented by purple red, gray green, gray yellow and pink mudstone, sandy mudstone, siltstone and fine sandstone, intercalated with gray and blue gray clayey limestone. The formation is 148 m thick.
Relationships and Distribution
Lower contact
Its base, marked by blue gray sandy mudstone or marl, is distinguished from the underlying Luohandong Fm made up of yellow arkose, and lies conformably on the latter.
Upper contact
Its top, made up of purple sandstone and mudstone, lies unconformably under the overlying Paleogene Gansu Gr.
Regional extent
The present formation is distributed in the northwestern and southwestern parts of Shaanxi-Gansu-Ningxia basin, and is observed in the western part of Otog Qi, the western part of Hanggin Qi and Ejin Horo Qi of Inner Mongolia. It is blue gray, gray green, brown gray and brown red mudstone intercalated with gray green and yellow gray calcareous fine sandstone and marl. In Ganyang and Longxian of Shaanxi, it is represented by tangerine and light brown mudstone and sandy mudstone intercalated with marl and sandstone, generally ranging from 178 to 446 m in thickness. In Gansu, it is exposed in Huanxian, Chongxin and Jingchuan, which has become coarser and thickened from north to south, 96 m in the north and 555 m in the south. In Ningxia, it is mainly found down the borehole at Yanchi.
GeoJSON
Fossils
In Otog Qi of Inner Mongolia, it yields Pisces Lycoptera woodwardi, L. kansuensis and Sinamia sp.; Ostracods Cypridea unicostata, C. yumenensis, C. koskulensis, C. justa, C. consulta, C. (Morinina) subrostrata, Rhinocypris cirrita; estheria Yanjiestheria sp.; sporopollen grains represented by the Cicatricosisporites-Densoisporites-Piceaepollenites assemblage. In Hanggin Qi, it yields bivalves Nakamuranaia chingshanensis, Sphaerium cf. selenginense, Fergaoconcha cf. subcentralis; estherias Ordosestheria wujiamiaoensis; and Reptilia Protoceratops sp. and Psittacosaurus youngi; in Ningxia estherias Xibeiestheria pora, X. yanchiensis and X. ovata and floras; and in Huanxian of Gansu Pisces, Chelonia and floras. It also yields insects, gastropods and Charophytes.
Age
Depositional setting
It is of lacustrine facies.
Additional Information