Grain sizes of susceptibility and anhysteretic remanent magnetization carriers in Chinese loess/paleosol sequences

[1] Detailed rock magnetic studies show that susceptibility (mass-specific c) and anhysteretic remanent magnetization (ARM) of the Chinese loess/paleosol sequences are carried by almost identical magnetic carriers. Therefore the ratio c/cARM (or equivalently cARM/c, where c is defined as c c0, and c0 is the intercept susceptibility of the plot of c versus ARM, and cARM is field-normalized ARM) can be used to quantify the grain size of c and ARM carriers. By determining this ratio for three Chinese loess/paleosol profiles (Jiuzhoutai, Yuanbao, and Yichuan) characterized by different degrees of environmentally controlled pedogenesis and sedimentation rates, we show that the lower grain-size limit of aeolian magnetic particles in the less pedogenically altered loess units is about 100–300 nm, in the finer-grained pseudosingle domain (PSD) grain-size range. In contrast, the grain sizes of pedogenically produced magnetic particles for mature paleosols dominantly cover both the superparamagnetic (SP) and single-domain (SD) ranges. On the basis of plots of c/cARM against c, samples can be divided into four regions (I, II, III, and IV). Region I corresponds to the least pedogenically altered primary loess samples, with c/cARM of 0.165–0.24. Samples i