Enhancement Mechanisms of Magnetic Susceptibility in the Chinese Red-Clay Sequence

[1] Little is known about the mechanisms of magnetic susceptibility (χ) enhancement for the red-clay sequence on the Chinese Loess Plateau (CLP), in comparison to the overlying loess-paleosol sequence. Here we present a rock magnetic study of the red-clay sediments from the central CLP. Our results show that frequency dependence of χ (χfd = χlf − χhf, where χlf and χhf are χ measured at 470 Hz and 4700 Hz, respectively), χlf, and susceptibility of anhysteretic-remanent-magnetization (χARM) are linearly correlated within the red-clay sequence. This linear correlation indicates that the pedogenic magnetic minerals of the red-clay have a rather uniform grain size distribution as in the loess-paleosol sequence, and the grain size is independent of the degree of pedogenesis. Nevertheless, red-clay sediments are slightly more enriched in superparamagnetic magnetic particles than the overlying loess-paleosol sediments as indicated by the higher slope of the regression line between χfd and χlf.