Variation of Sediment Magnetic Properties and Their Paleoenvironmental Implications in Yangtze River Delta During 30–50 Ka B.P.

Identifying the variability in and driving forces of relative sea-level (RSL) change in the Yangtze River Delta during 30-50 ka B.P. is vital for understanding global climatic and RSL changes. In this study, the environmental magnetism of sediments in the Yangtze River Delta was systematically studied for the period 30-50 ka B.P. based on the optically stimulated luminescence (OSL) dates. Detailed magnetic measurements, including hightemperature kappa-T, magnetic hysteresis loop, isothermal remanent magnetization acquisition, and demagnetization curve measurements illustrate that the predominant magnetic contribution of core YZ07 is from magnetite, with a small contribution from hematite. Detrital input may be the primary source of magnetic minerals according to the chi/chi(fd)% and chi(ARM)/chi correlations. In addition, the positive relationship between chi and the RSL curve indicates that chi is a valid indicator of RSL change. Additionally, comparing chi, RSL curves, and delta O-18 dates of the stalagmites demonstrated that climatic change influenced the RSL change, which mainly affected the concentration of magnetite. The results are conducive for understanding the response mechanism of magnetic indicators to relative sea-level change, and provide a scientific basis for encouraging for future work in understanding climate variability.