Terrestrial Permian-Triassic boundary in southern China: New stratigraphic, structural and palaeoenvironment considerations

The Permian-Triassic boundary is located above the main Phanerozoic terrestrial and marine biotic crisis. Southwest China (eastern Yunnan and western Guizhou) is considered as an ideal place in Asia to study the terrestrial Permian-Triassic boundary, its correlation with the stratigraphically equivalent marine deposits, and to discuss the contemporaneity between the marine and terrestrial extinctions. The Chahe and Zhejue sections, which have already been studied in detail, especially using δ13C isotopic analyses for both sections and geochronology for the Chahe section, are considered to be the reference terrestrial sections to discuss changes (both through time and space) in macroflora, pollen diversity and paleoenvironment. Based on new structural analyses of these sections, we demonstrate that they have been strongly affected by polyphase deformations and are, therefore, not suitable to discuss the vertical and/or lateral evolutions of the depositional environments within the Permian-Triassic succession. The use of the Chahe and Zhejue sections to study the contemporaneity between marine and terrestrial extinction events at the end of the Permian in southern China, as well as the stratigraphic correlations and the palaeoenvironment reconstitution of western Guizhou and eastern Yunnan, therefore, must be reconsidered.