Registration of Precession Signal in the Last Interglacial Paleosol (S1) on the Chinese Loess Plateau

Abstract

AbstractSolar insolation plays an essential role in driving orbital‐scale East Asian Monsoon (EAM) variability. Unlike Chinese speleothem δ18O records characterized by dominant precessional cycles, many loess proxies from the Chinese Loess Plateau (CLP) usually display damped precessional‐scale variability. To reconcile the precessional monsoon variability recorded in two classic archives, it's critical to investigate which factor can significantly affect the sensitivity of loess proxies to precessional forcing. In this study, we synthesize grain size (GS) and magnetic susceptibility (χ) results of 18 paleosol (S1) profiles over the CLP, with effort to evaluating the relative impacts of sedimentation rate (SR), and pedogenesis on the precessional signal intensity (PSI) during the last interglaciation. Based on unified grain‐size age models, amplitude contrast between normalized GS and χ variations of five substages of the last interglaciation is employed to infer the PSI. The results indicate that precessional signals are evident in the GS/χ records of the high‐SR loess profiles on the northern and western CLP. Comparison of the PSI variations with the SR and mean annual precipitation (MAP) changes suggests that the GS‐PSI is positively correlated to the SR changes, while the χ‐PSI is negatively/positively related to the SR/MAP changes. Our results confirm that distinct precessional cycles in high‐resolution loess proxies permit a plausible reconciliation of monsoon variability recorded in Chinese loess and speleothem.