Sedimentary records of sea-level fall at the end-Permian in the upper Yangtze Region, southern China: Implications for the mass extinction

Abstract

Abstract Sea-level fall is considered one of the significant factors leading to the end-Permian mass extinction. Our study focused on the relative sea-level changes in Beifengjing section which deposited in shallow-water platform and Shangsi section which deposited in deep-water trough. The results indicated a sea-level fall during the Permian—Triassic transition in the Upper Yangtze region. Considering that there is no significant change in fossil abundance in the strata following the two sea-level falls observed in the Beifengjing section, we conclude that the reduction of shallow marine habitat caused by sea level fall alone was insufficient to cause the mass extinction. However, sea-level fall did exacerbate the input of terrestrial debris into the ocean, leading to the deterioration of the marine environment (e.g., soil-induced turbidity and eutrophication). Furthermore, the presence of multiple layers of volcanic tuff near the lithostratigraphic boundary between Permian and Triassic in both sections suggests frequent volcanic activity during sea-level fall. Therefore, we propose that the combined adverse effects of volcanic eruptions, sea-level falls, and other events exceeded the threshold for biological survival, ultimately resulting in the catastrophic end-Permian mass extinction.