Yali Fm

The type section is lies between Yali Village and Naxing Village of Nyalam County, along the east side of the Sino-Nepal Highway, Xizang Autonomous Region (Tibet). It was named by Zhang Bingao and others in 1973, and published by Wang Yigong in 1974.

Claystone, Limestone and Sandstone. Split into a lower "Xiayali" and an upper "Shangyali" formation. For the Lower Yali ("Xiayali"), the Lower part is composed of gray-black shale intercalated with thin-bedded fine-grained sandstone and siltstone, 22 m thick; the Upper part is of gray limestone, 30.2 m thick. In the Upper Yali ("Shangyali") Fm, the Lower part consists of gray thin- to moderately thick-bedded clayey limestone, yielding small solitary corals Rhopalolasma minor and Plerophyllum sp.; and its Upper part is dominated by light-gray medium-grained quartz sandstone, intercalated with sandy and calcareous shales and minor conglomerate and siltstone. Total thickness was cited as 61.8 m in Dev Lexicon, but 1343 m in Carb Lexicon (but maybe Dev Lex referred only to the Devonian portion?).

Lower Yali - Upper part yields Ammonoids Attendorfia yaliana and Imitoceras xizangensis; Conodonts Siphonodella sulcata, S. cooperi and Polyganathus purus; Ostracods Necrateris rectagona and Amphissites centronotus.

Upper Yali – Lower part has small solitary Corals Rhopalolasma minor and Plerophyllum sp.; and, going eastward along strike to Pazhug of Tingri County, Longiclava sp., Hapsiphyllum sp., Cumminsia sp., Zaphrentites subcarruthersis and Beichuanophyllum pazhugense have been found. Upper part yields Brachiopods Syringothyris lydekkeri, Tolmatchoffia sp., Marginirugus cf. magnus, Schuchertella cf. gueizhouensis and Fusella yaliensis, Eochoristites sp.; Bivalve Pernopecten cf. clypeatus.

It contains conodont Palmatolepis glabra. In the Bazuo-Kede area of Dinxi County, the Formation yields conodonts of Palmatolepis Marginifera Zone and Bispathodus sulcata Zone.