Turbulent paleoenvironment linked to astronomical forcing during the Permian-Triassic transition

The Milankovitch cycles are essential for establishing high-resolution chronological frameworks, which can provide a reliable timescale for biological and environmental events. However, astronomical solutions for the Paleozoic are still imperfect. Moreover, global paleoenvironmental turbulence during the Permian-Triassic (PT) transition caused interference with most proxies reflecting astronomical cycles. This study discovered that the Sb/Cd series can reflect astronomical cycle signals through a time-series analysis of geochemical elemental data from cores around the Lopingian-Lower Triassic in the Lower Yangtze region. Combined with zircon SHRIMP dating of volcanic ashes, a reliable absolute astronomical timescale with a duration of 2.5 Myr was established from 100-kyr eccentricity-tuned results. Based on the coupling analysis of palaeoenvironmental proxies, this study evaluated the effect of astronomical forcing and volcanism on the paleoenvironment. The sea level change was influenced by obliquity during the Lopingian-Early Triassic. During the Wuchiapingian-Changhsingian (WC) and PT transitions, regional volcanic activities at South China and the Siberian Traps Large Igneous Province (STLIP) intervened the normal trend of a low-temperature arid climate dominated by the obliquity forcing, respectively. Thus, South China exhibited a hot humid climate during the WC and PT transitions. Conversely, the low-temperature climate in South China was significantly modulated by obliquity forcing during the middle Changhsingian. Besides the influences of intense igneous activities and related environmental effects, disruption the long-term stable low-temperature environment by the abnormal high-temperature around the PT transition was a tremendous challenge to the biological ecological adaptation, and thereby may have contributed to the end-Permian mass extinction.