Relevance of ultrafine grains in the magnetic fabric of paleosols

The effects of pedogenic magnetic grains on the magnetic fabric of paleosols were investigated using samples from the Paks loess profile, Hungary. Rock magnetic experiments, electron probe microanalysis, and scanning electron microscopy revealed characteristic signatures of (post-)pedogenic influences on the original sedimentary fabric. No differences were observed between low- and high-frequency fabric, suggesting that the particle orientation distribution of superparamagnetic particles was isotropic or nearly isotropic. In some samples with low frequency dependence, the presence of superparamagnetic contributors was negligible compared to the coarser magnetic contributors. No inverse fabric was identified, indicating that stable single-domain magnetite had a negligible contribution to the fabric. Despite differences in the magnetic mineral content, the relative contributions of coarse and ultrafine grains appeared to be constant. Various methods of altering or preserving the sedimentary fabric during (post-)pedogenic processes were described. Some processes, such as the hydromorphic effect, weakened the anisotropy of the original fabric and strengthened the orientation of the grains. Meanwhile, other processes, such as post-burial, compaction of materials, and fragmentation, strengthened the foliation with increasing anisotropy. Processes that can fix the fabric and magnetic fabric of paleosols will allow us to use the fabric to determine the paleowind direction in the Pleistocene interglacial periods in future studies.