Heiyanwo Fm

The type section is lies at Shawozi around the lime kiln on the opposite bank of Changtanzi Village, Beichuan County, Sichuan. It was named by Hou Hongfei et al. in 1988.

Dolomitic limestone. Lower part consists of gray-white massive and crystalline dolomite and dolomitic limestone, intercalated with compact limestone, gray thin-bedded clayey limestone and shale, and the shale is locally of an irregular oolitic texture. Thickness 90 m. T he Upper part is composed of gray massive clayey limestone, gray-white massive micritic dolomitic limestone, containing chert strips and nodules. Total thickness >151 m.

Lower part yields Corals Pseudouralinia sp. and Uralinia zhongguoensis; Foraminifers Labechia sp. and Cystostrona sp.; Brachiopods Camarotoechia kinlingensis and Leptagonia analoga. Limestones in Upper part contain Coral Pseudouralina minor; Brachiopods Plicatifera cf. Fallax, Camarotoechia kinlingensis, Spirifer aff. kasachstanensis, etc.

It is interpreted as a littoral-neritic carbonate facies