Soil magnetism and climatic variation across the Shanxi Loess Plateau, China

Abstract

Soil magnetic parameters are increasingly being linked to climatic and environmental variation, and thus provide an useful information for tracking perturbations in terrestrial environments. Climate data and the magnetic properties of modern topsoil samples were examined across a 680 km transect of the Shanxi Loess Plateau and compared to regional climate data – including temperature and precipitation. The results revealed median values of magnetic susceptibility (79.49 × 10−8 m3kg−1), saturation isothermal remanent magnetization (SIRM 1058.37 × 10−5Am2kg−1), and anhysteretic remanence magnetization (ARM 14.29 × 10−5Am2kg−1), respectively. Soils were also shown to contain a high prevalence of super paramagnetic (SP) grains, as indicated by frequency dependent susceptibility above 5%. Soil magnetic susceptibility, SIRM, and ARM showed a significant correlation with the mean annual precipitation (MAP), while a weak association was observed between ARM and mean annual temperature (MAT). The spatial distribution of topsoil magnetism in the region suggests a strong gradient from north to south, which is consistent with a moderate rainfall gradient of 350– 700 mm.yr−1. Overall, these data showed that soil magnetic properties across the Shanxi Loess Plateau are similar to other loess-derived soils in China and reflect the influence of climatic parameters in their genesis, especially rainfall.