Long-Term Variations in the Lithogenic Susceptibility of Chinese Eolian Deposits Since the Late Pliocene

In contrast to the extensive investigation of the pedogenic magnetic component, the origin of long-term variations in the lithogenic susceptibility of Chinese eolian deposits has rarely been investigated. In this study, we conducted a linear correlation analysis of rock magnetic parameters of representative loess-red clay sections from the Chinese Loess Plateau. We found that lithogenic susceptibility of the deposits exhibited three dramatic increases, at similar to 2.75, 0.6, and 0.13 Ma. We argue that intensive erosion or physical weathering in the NE Tibetan Plateau, induced by late Pliocene global cooling and tectonic uplift, may be responsible for the increases in lithogenic susceptibility over the past 3.6 Ma. Furthermore, the magnetic properties of water-reworked sediments deviate from the linear regression line for the eolian deposits of the Chinese Loess Plateau, suggesting that regression analysis may provide a rapid method for distinguishing between sediments of eolian and fluvial origin in the region. Plain Language Summary Rock magnetic properties of eolian loess and red clay deposits in North China provide critical information for our understanding of East Asian monsoon variability and the link between terrestrial and marine paleoenvironmental records. However, long-term temporal variations in the lithogenic susceptibility of Chinese eolian deposits and their driving mechanisms remain unclear. Evidence based on linear correlation analysis and previous geochemical extractions for five loess-red clay sections from the Chinese Loess Plateau suggests that the lithogenic susceptibility of Chinese eolian deposits exhibits three dramatic increases over the past 3.6 Ma. Based on the analysis of the major tectonic and climatic events, we conclude that intensive erosion or physical weathering in the NE Tibetan Plateau, rather than increased wind speeds, which were induced by late Pliocene global cooling or/and tectonic uplift, may account for the increase of the lithogenic susceptibility of Chinese eolian deposits. This finding potentially provides new insights for understanding of the impacts of tectonic activity and global cooling on the lithogenic magnetic component of Chinese eolian deposits.