East Asian lake hydrology modulated by global sea-level variations in the Eocene warmhouse

Abstract

Lake hydrological change and its driving mechanisms in the Eocene warmhouse climate are important to evaluating environmental and ecological changes induced by global warming. Our limited understanding of lake hydrological changes during the Eocene is in part due to the scarcity of well-dated and continuous terrestrial records. Here we refine the middle-late Eocene cyclostratigraphy and decipher high-resolution lake hydrology changes using sedimentary noise modeling and proxy data at four terrestrial basins (Dongying Depression, Nanxiang Basin, Jianghan Basin, and Fushun Basin) in mid-latitudes of East Asia. Our new astrochronology provides a robust timescale for the period of 48.5-38.5 Ma, and our tuned magnetostratigraphy is at least comparable with other timescales between Chrons C18n.1r and C20n. The new astrochronology reveals synchronous lake-level changes in the four basins in East Asia following 1.2 Myr obliquity and 2.4 Myr eccentricity cycles, indicating astronomical forcing on lake-level changes. The 2.4 Myr cycles of lake-levels are generally in phase with 2.4 Myr cycles of global sea-level changes, suggesting that East Asian lake hydrology was modulated by global sea-level variations in the Eocene warmhouse. Therefore, global sea-level variations may be an important driver of East Asia hydroclimate and freshwater resources.