科学前沿

The Permian–Triassic transition witnessed the extinction of some 90% in the marine realm and 70% taxa on land. Paleoclimate seems to have played a key role in this largest Phanerozoic biodiversity crisis. However, to understand past climatic conditions on land, which display significant spatial variability (e.g., in terms of local temperature and humidity), regional sedimentary records need to be investigated in detail to reconstruct local paleoclimate and inform larger scale models. Here we present a paleosols study of the Permian–Triassic Shichuanhe section in the Shaanxi Province of the central North China Basin. Based on field observation and microscopic study, six types of paleosols have been identified as calcic Inceptisol, vertic Aridisol, gleyed Vertisol, gleyed Inceptisol, calcic Vertisol, and gleyed Aridisol. Fe quasi-coating and calcite hypo-coating disappear in the Early Triassic, taking Fe depleted nodules as major morphological pedofeature. Mean annual precipitation was calculated as 320 ± 147 mm/yr in the latest Permian and 520–680 ± 147 mm/yr in the late Early Triassic. The results suggest local aridity in the latest Permian, and intensified precipitation in the late Early Triassic, contributing to the mass extinction and recovery in its aftermath on land.