A Review of Studies on Global Changes of Sea Level Across the Permian Triassic Boundary

Key words: 
• Permian-Triassic boundary /
• sea-level change /
• sub-aerial exposure /
• mass extinction event

Abstract: The issue on sea-level changes across the Permian-Triassic boundary (PTB) has been disputed by the sedimentologists for a long time. It may also have relation with the largest mass extinction event during the transition of Permian-Triassic. However, it is not quite clear about the process and mechanism of the change of sea level in light of previous studies from local- and small-scale materials. The lack of reliable evidence from integrated perspectives would go against the identification of the process and duration of global sea-level variation. In this study, we systematically reviewed the literatures on the issue of sea-level changes during the transitions of Permian-Triassic, and summarized the main views including:(1) successive transgression, and (2) regression and following quick transgression. This study also compiled the development processes of these two different views, sedimentary features in diagnostic sections, the possible reasons of sea-level rise/fall, as well as the relationship between mass extinction and sea-level changes. Meanwhile, the causes of dispute on sea-level changes in the PTB were discussed preliminarily from available evidence. The aim of this study is to provide some clues to further recognize the process of sea-level changes during the PTB, and to provide substantial evidence to understand the background of global sea-level changes during the Permian-Triassic transition.