Obliquity-driven moisture changes in Qaidam Basin in Late Miocene during low eccentricity period

The present interglacial period is at a period of low eccentricity, and the ice sheets in the northern hemisphere are gradually melting due to the global warming. Understanding the variation and the mechanism of dry-wet alternation in Asian inland during low eccentricity period under the ice-free background of the northern hemisphere is very important to predict the future environmental changes in the area. At present, little attention is paid to high-resolution records of environment variations during low eccentricity periods in inland Asia, which limits the understanding of moisture changes and the mechanism in the region. The Qaidam Basin, located at the edge of East Asian monsoon rain zone, is very sensitive to dry-wet climate alternation. In this study, we selected the fluvial-lacustrine strata of the Dahonggou section in the northeastern Qaidam Basin, along which the frequency magnetic susceptibility was measured, to reconstruct the high-resolution moisture history of the Late Miocene (12～9 Ma). Results revealed typical dry-wet changes and show that the local climate change has a clear 40-ka cycle, corresponding to the obliquity in typical low eccentricity condition when the precession amplitude is small during 9.4～9.2 Ma, 9.8～9.6 Ma, and 11.4～11.2 Ma. It suggests that obliquity factor may rise and become a dominant factor on orbital regulation of environment in arid area. This finding has important implications for understanding future climate change.