Precise dating of the Middle Permian: Zircon U-Pb geochronology from volcanic ash beds in the basal Gufeng Formation, Yangtze region, South China

► Volcanic ash beds are found in the basal Gufeng Formation of the Middle Permian in South China. ► Zircons from two volcanic ash beds yield precise ages of 272.0 ± 5.5 Ma and 271.5 ± 3.3 Ma. ► The age of 272 Ma may represent the first precise date for the Lower/Middle Permian boundary.