Environmental magnetism linked to weathering processes: A study on surface soils from an East Antarctic oasis

Abstract

We determined and discussed the mineral magnetic properties of the soil samples (n = 78) from the Schirmacher Oasis, East Antarctica. Environmental magnetism analysis was conducted to identify the mechanisms controlling the formation and distribution of iron oxide minerals such as magnetite and hematite. Magnetic susceptibility (χ_lf) exhibited a mean (± SD) value of 109.5 (± 76.6) × 10⁻⁸ m³kg⁻¹, indicating the presence of magnetically strong minerals. A statistically significant correlation (r = 0.79; p < 0.01) between χ_lf and saturation isothermal remanent magnetization (SIRM), the S-ratio values (0.97–0.99) and temperature-dependent magnetization measurements, suggests that low-coercivity magnetic minerals, such as magnetite, primarily regulate the magnetic signal. The percentage of frequency-dependent susceptibility remains below 2 % for most samples, indicating an insignificant presence of ultrafine superparamagnetic grains. The χ_ARM/SIRM parameter (mean (± SD) values of 53.7 (± 26.3) × 10⁻⁵ mA⁻¹) suggests a predominance of coarse-grained magnetic minerals, while magnetic hysteresis parameters indicate the dominance of multidomain magnetic grains, with minor proportions of single-domain and superparamagnetic grains. Various inter-parametric ratios reveal the absence of bacterial magnetite, anthropogenic magnetite, and authigenic greigite, suggesting that the magnetic minerals in these Antarctic soils from Schirmacher Oasis predominantly result from weathering processes.