Yabei Fm

The type section is lies on the north flank of the Beishan syncline, Yamansu, Xinjiang. It was named by Zhou Shouyun et al. in 1981, and formally cited in The Paleozoic Erathem of Xinjiang in 1991.

Siltstone and Chert. In the type section, the Lower part is composed of gray calcareous siltstone intercalated with light green-gray chert and minor gray-green to gray thin-bedded calcareous siltstone and minor calcareous fine-grained sandstone, 3301 m thick (!). On the south flank of the syncline, the Upper part of the formation consists of dark-gray medium- to thick-bedded chert interbedded unevenly with yellow-gray and brown-gray thin-bedded shale and schistose clayey siltstone, in faulted contact with the underlying Wutongwozi Fm. Exposed thickness 1457 m.

Only crinoid stem fragments are found in the formation.