Site-specific variability of loess and palaeosols (Ruma, Vojvodina, northern Serbia)

Abstract

The study of temporal variations in soil intensity has mostly been limited to specific sites. However, it is important for correctly interpreting the stratigraphy and palaeoclimatic significance of loess and palaeosols series to understand the reasons for the spatial variability. More specifically, pedogenetic and sedimentological properties should be evaluated separately. This is particularly well illustrated at the Ruma site (Serbia). In this paper we focus on macroscopic soil characteristics and sediment grain-size properties. The type-succession shows three interglacial pedocomplexes (V-S1,V-S2 and V-S3) separated by loess layers that include at least one interstadial pedocomplex in the uppermost loess layer. All sediments show a bipartite grain-size distribution (a coarser-grained silt-dominated one and a fine-grained one (<16 μm)). The interglacial palaeosols show a slightly finer-grained mean grain size than the interstadial soils and loess layers, which is entirely determined by the higher proportion of the fine subpopulation. Laterally, the palaeosols vary from a black organic, chernozem-like soil to a brown-coloured inorganic soil. There are no significant differences in grain size between the two soil types. In the vertical succession, the jumps in grain-size do not correspond always with the soil colour. Furthermore, there is no clay illuviation. It may be concluded from this multi-proxy study that the locally higher amount of the fine-grained component seems corresponding with a more humid depositional environment. Another important conclusion is that all loess shows identical grain-size composition and thus that interglacial loess with distinct finer grain-size as is the case in Asian loess (also in the coarser subpopulation) is clearly absent.