THE MAGNETIC-PROPERTIES OF PARTICLE-SIZED SAMPLES FROM THE LUO-CHUAN LOESS SECTION - EVIDENCE FOR PEDOGENESIS

Measurements of magnetic susceptibility and of laboratory remanences have been carried out on particle size fractions of loess and palaeosol samples from Luo Chuan, China. They show that the sub-micron clay fraction of the palaeosol is greatly enriched in fine-grained (< 0.03-mu-m) ferrimagnetic minerals and thus confirm the importance of secondary pedogenic components in the magnetic record from the section. The assemblages of magnetic minerals in both the loess and the palaeosol are interpreted as strongly bimodal with inferred detrital and pedogenic contributions to both. Climatically modulated magnetic variations between palaeosols and intervening loess layers arise from fluctuations in the absolute and relative importance of these two components. Of the two, the pedogenic component appears to exercise the stronger control on susceptibility variations in these Luochuan samples.