Naobaogou Fm

The type section is located in the east of the Tongshengmao Village to the east of the Shiguai Mine of Baotou City, Inner Mongolia (110°26′, 40°38′). It was named by Gu Zhiwei in 1955, and was cited officially in the "Regional Stratigraphic Chart of North China Region-Inner Mongolian Fascicle" (1978).

Sandstone. Composed mainly of variegated polymictic conglomerate, sandy conglomerate and pebble-bearing feldspar-rich sandstone, intercalated with clayey siltstone, locally of calcareous conglomerate, intercalated with a small amount of siltstone, with all the rocks having been chloritized universally. Its basal part is composed of grey-green pebble-bearing sandstone. Lower part is composed mainly of grey-purple sandstone, intercalated with purplish-red shale. Middle part consists of interbeds of purplish-red shale and dark-purple sandstone. Upper part is composed largely of dark-purple sandy shale, intercalated with purple fine- and medium-grained sandstone and a small amount of coarse-grained sandstone. The pebbles of the basal conglomerate tend to occur in an imbricate arrangement, with the pebble-bearing coarse-grained sandstone being characterized by the development of large-scale trough cross-bedding, as well as monodirectional or bidirectional oblique beddings. Total thickness is 1286 m.

Li Jinling and Cheng Zhengwu (1997) reportedly collected Vertebrate fossils in the area of the Jinluandian Mt. such as Dicynodontidae, Therocephalia, Captorhinomorpha, Pareiasaurus, etc.

It is interpreted as fluvial deposits. The occurrence of asymmetric ripple marks, mud cracks and rain imprints in the interbeds demonstrates that it represents intermontane river-facies deposits and the paleocurrent directions are of northeast trend.