Factors controlling the spatiotemporal variability of dust magnetic susceptibility across the Chinese loess Plateau and eastern Tibetan Plateau

To explore the factors controlling the spatiotemporal variability of dust magnetic susceptibility (SUS) across tectonically stable (Chinese Loess Plateau, CLP) and tectonically active (eastern Tibetan Plateau, ETP) regions, the SUS and grain-size records of the Jingyuan and Lantian loess-paleosol deposits from the CLP, and Lixian lacustrine sediments from the ETP, were analyzed. The results show that, spatially, SUS decreases substantially from SE to NW in the CLP, and from the CLP to the ETP; and temporally, SUS increases significantly both in the CLP and the ETP during warm periods. The former is consistent with pedogenic contributions previously proposed, while the later responds to the enhanced seismic activities and foehn effect during warm period. The correlation analysis shows that the strongest positive correlation between SUS and 2-10 & mu;m fractions in the CLP indicates a substantial contribution of fine particles to magnetic minerals, which has been underestimated in the earlier studies. The strongest positive correlation between SUS and coarse-grained fractions in ETP reveals that SUS is mainly controlled by frequent release of magnetic minerals from bedrock caused by tectonic activities. These results reflect different controlling factors of SUS changes under different tectonic backgrounds. Therefore, the correlation analysis between SUS and grain-size fractions can be used as a simple and effective method to sensitively reveal regional tectonic activity, and effectively trace the Earth surface processes including material supply, transport dynamics, and sedimentology.