Sensitivity analysis of magnetic susceptibility under different climatic conditions during the late Pleistocene-Holocene period

Abstract

Understanding the climate change experienced by the Loess Plateau in China from the end of the late Pleistocene to the Holocene is helpful for exploring global palaeoclimate change and predicting future climate change. However, sensitivity studies on palaeoclimate proxies under different geological periods and different climatic conditions are still lacking, which affects the accurate identification of palaeoclimate changes and the precision with which future climate change predictions can be made. Three soil profiles in Luochuan County were sampled, and the magnetic susceptibility (χlf), frequency-dependent susceptibility (χfd%), clay content (<0.005 mm), clay/coarse silt ratio, calcium carbonate content (CaCO3), and total content of organic carbon (TOC) of the profiles were analysed. The results showed that the climate changed from dry and cold to warm and wet to dry and cool since the end of the late Pleistocene. The precipitation (MAP) and temperature (MAT) since the end of the late Pleistocene were reconstructed by using the magnetic susceptibility of different soil particle size fractions (>2 mm, 2–1 mm, 1–0.5 mm, 0.5–0.25 mm, <0.25 mm), and the results were compared with those from other researchers. The results showed that the magnetic susceptibility of the fine fraction (<0.25 mm) was more sensitive at 0–3200 cal. yr. BP, 8500–13,000 cal. yr. BP, and 15,000–25,000 cal. yr. BP, while that of the coarse fraction (>0.25 mm) was more sensitive at 3200–8500 cal. yr. BP. Based on this finding, the precipitation and temperature of this period were reconstructed. This study provides a research method for selecting suitable climate proxies to describe climate changes in different geological periods to accurately conduct quantitative or semiquantitative assessments of climate change.