Fengcheng Fm

The type section is located at Fengcheng in a shaft on the northern side of the Klamai Basin (Xinjiang Province), and represents a comprehensive section. No reference section has been appointed. It was named by Yong Tianshou et al., in 1983, and was first cited publicly by Jin Yugan et al. in 1987.

Volcanic tuffs and Dolomite: It is a suite of clayey tuffaceous dolomite and dolomitic siltstone, intercalated with thin layers of sandstone, siltstone and limestone. The main part consists of grey-black tuffaceous dolomite and dolomitic tuff, being silicified, intercalated with thin-bedded sandstone and grey tuffaceous breccia; and the top part is composed of grey-black and grey-green siltstones. In the area from Wulhe to Huangyangquan the visible thickness of the formation reaches as great as 700-900 m.

Spore-pollen fossils are characterized by a predominance of plant pollens constituting 90%-100%, with the Disaccites as represented by Protohaploxypinus, Hamiapollenites, Striatopodocarpites and Striatobietites being predominant, and with the Vittatina constituting only a small amount. Among the Cicatricosisporites it is the Disaccites that are predominant, and the Alelesacciti comes second. Among the former it is the Aletes that are in majority, comprising chiefly the Pityosporites, as well as Abiespollenites and Limitisporites. The Aletesaccits pollens are represented largely by Cordaitina, less by Florinites and Parasaccites. The content of the spores of psilopsid is less than 10%, whose major member is the Grandisporites. This particular assemblage is possessed of a fairly high content of cicatricose pollen which commonly exceeds 50%, and the Hamiapollenites pollenites which were luxuriant in the Permian Period makes up 12-15% of the whole assemblage, and for this reason it can be correlated with the spore-pollen assemblages of the Wulabo Fm and the Jingjingzigou Fm on the southern margin of the region.