Expansion/shrinkage history of the Paratethys Sea during the Eocene: New insights from eolian Red Clay records in the Altyn Mountains, northern China

Uplift of the Tibetan Plateau, expansion/shrinkage of the Paratethys Sea, and global climate are three major forcings for central-east Asian climatic and environmental variations during the Cenozoic. However, knowledge of expansion/shrinkage history of the Paratethys Sea is much less well known in comparison with the other two forcings. Here, we present a first multiple-parameter environmental magnetic and diffuse reflectance spectroscopy study of the Eocene eolian Red Clay deposits (similar to 51-40 Ma) in the Xorkol Basin of the northeastern Tibetan Plateau, which is near the easternmost maximum boundary of the Eocene Paratethys Sea. The first detailed Eocene expansion/shrinkage history of the Paratethys Sea was reconstructed based on the hematite content of the Eocene Red Clay, which shows remarkable consistency with the previous low-resolution Paratethys Sea paleowater depth record in the southwestern Tarim Basin. These results demonstrate that the Paratethys Sea experienced a three-stage (shrinkage-expansion-shrinkage) evolution between similar to 51 and 40 Ma, with boundaries at similar to 46.2 and 42 Ma. Superimposed on this framework, the Paratethys Sea experienced four times of rapid shrinkages at the expansion phase (shows 400-kyr cycles) during similar to 44-42 Ma modulated by eccentricity forcings. These new results are of great significance to evaluate respective role of Tibetan uplift, global climate, and Paratethys Sea area variations in Asian climate and environmental change over the Eocene.

Automated summary

This study presents a reconstruction of the expansion/shrinkage history of the Paratethys Sea based on the analysis of Eocene eolian Red Clay deposits in the northeastern Tibetan Plateau. The results reveal that the Paratethys Sea experienced a three-stage evolution between approximately 51 and 40 million years ago, with four rapid shrinkages occurring during the expansion phase.