The Ladinian–Carnian conodont fauna at Yize, Yunnan, southwestern China, with implications for conodont palaeoecology and palaeogeography

AbstractSubdivisions of Ladinian–Carnian boundary beds and the lower Carnian strata in South China are challenging owing to a paucity of west Tethyan ammonoids. We investigated a conodont fauna in a continuous section at Yize in eastern Yunnan Province to provide a biostratigraphic solution. Five genera and 24 conodont species are recognized, and five conodont zones are established. The zones are, in ascending order, theParagondolella inclinataZone, theQuadralella polygnathiformisZone, theQuadralella praelindaeZone, theQuadralella auriformisZone and theQuadralella robustaZone. The Ladinian–Carnian boundary is provisionally defined by the first occurrences ofQuadralella polygnathiformisandQuadralella intermediain the cherty limestone member of the Zhuganpo Formation. Regional correlations via conodont biostratigraphy indicate that the Zhuganpo Formation is probably diachronous, with a maximal range spanning the upper Ladinian to the lower Carnian. Amongst all common late Ladinian – early Carnian conodont genera,Paragondolella,QuadralellaandMazzaellaare probably cosmopolitan.Budurovignathuswas restricted to a few basins and probably preferred offshore or deep-water environments.