Late Pleistocene paleosol formation in a dynamic aggradational microenvironment - A case study from the Mala nad Hronom loess succession (Slovakia)

The geomorphological characteristics of the loess succession at Male nad Hronom (Slovakia) mean that it provides a valuable opportunity for the investigation of differences in soil formation in various topographic positions. Along with the semiquantitative characterization of the paleosols (on the basis of physical properties, texture, the characteristics of peds, clay films, horizon boundaries), high-resolution field magnetic susceptibility measurements and sampling were carried out along four different sections of the profile. Samples for luminescence dating were also taken, in order to establish the chronostratigraphical position of the paleosols studied. The comparison of various proxies revealed the differences in soil formation in a dynamic aggradational microenvironment for the same paleosol horizons located in various positions along the slope. Contrary to expectation, paleosols developed in local top or slope topographical positions did not display significant differences in e.g. in their degree of development, nor the characteristics of their magnetic susceptibility curves. In the case of paleosols in positions lower down the slope, signs of quasi-permanent sediment input could be recognized as being present as early as during the formation of the soil itself. This sediment input would seem to be surpassed in the case of pedogenesis strengthened by the climate of the last interglacial (marine isotope stage MIS 5). Pedogenesis seems to be sustained by renewed intense dust accumulation in the Late Pleistocene, in MIS 3, though compared to MIS 5, the climate of MIS3 did not favor intense pedogenesis. Despite the general belief that loess series formed in plateau positions can preserve terrestrial records without significant erosion, in the case of the Male nad Hronom loess this is not so. Compared to the sequence affected by erosional events in the local top position, the sequence affected by quasi-continuous sediment input in the lower slope position seems to have preserved the soil horizons intact.

Automated summary

The geomorphological characteristics of loess succession at Male nad Hronom in Slovakia provide a valuable opportunity to investigate differences in soil formation in various topographic positions. The study revealed differences in soil formation dynamics along the slope, with paleosols in lower slope positions showing signs of quasi-constant sediment input. The climate conditions of the last interglacial and Late Pleistocene played a significant role in pedogenesis, with MIS 3 climate favoring intense dust accumulation. Despite erosion events, the sequence affected by sediment input in lower slope positions preserved soil horizons intact.