Xiujimqin Fm

The type section is located in the Nanshan Mt. to the west of the Xi’ujimqin Banner, Inner Mongolia, and the reference sections for the lower and upper lithologic members of the formation are located respectively in the area of a limekiln 8 km and the Haorehada area 17 km to the southwest of the Xi’ujimqin Banner, Inner Mongolia. It was named by Ueda Fusa-Kazu and Sasakura Sei-Fu in 1937.

Synonym: Xi'ujimqin Fm, Xiwuzhumuqinqi Fm

Clastics. Lower member is composed of yellow-green sandstone, siltstone, conglomerate, grey bioclastic limestone and siliceous rocks, with a thickness of over 1036 m. Upper member is composed of grey-green and grey-black massive carbonaceous siltstone and slate, intercalated with limestone lenses. There is no sign of direct contact between the Lower and the Upper members of the formation. Total thickness is 1202 m.

Its Lower part yields Brachiopods such as Waagenites aeguicosta, Anidanthus kolymaensis, Dictyoclostus zesiensis, Liosotella, Yakovlevia, Leptodus, Neospirifer moosakhailensis, Licharewia multiplicata, etc.; and Corals such as Tachylasma, etc. Its Upper part yields Brachiopods such as Fallaxoproductus sutungensis, Krotovia lineate, Neospirifer ravana, etc.; Ammonoids such as Daubichites; and Plant fossils (phytolites) such as Pecopteris, Paracalamites, Noeggerathiopsis, etc.

It is interpreted as shallow-sea facies clastic-rock deposits.