In high rainfall environments, eluvial-illuvial processes play a key role in pedogenesis. Vertical movement of clay results in the formation of a clay-rich (argic, Bt) horizon and leads to the formation of illuvial soils, which are widespread on a global scale and formed from different parent materials in various climates. There are not many studies of clay-rich illuvial soils on limestone in temperate humid climates. The aim of this thesis was to evaluate the geochemical and mineral composition and properties of illuvial soils in the Dinaric Karst area of Slovenia and to identify geochemical indicators of eluvial-illuvial processes. In the area of the Dinaric Karst, especially on the Karst plateau, in the regions of Dolenjska and Bela krajina, there are also soil types with a distinct red colour (red soil), whose colour has been linked to paleoclimatic conditions in previous studies. We were interested in the degree of illuviation of the red soils and the heterogeneity of these soils. In the research, we included 20 profiles of rendzinas (Leptosols/Phaeozems), three profiles of brown soils (Eutric Cambisols), five profiles of terra rossa (Rhodic Cambisols), and 15 profiles of illuvial soils (Luvisols) and analysed their pedological, geochemical and mineral properties, as well as the micromorphological properties of the selected profile. We found that illuvial soils are characterised by high clay content and high textural differentiation, with a mean clay ratio of 1.58 between the argic (Bt) and eluvial (E) horizons. Micromorphological analysis of the selected profile showed that the amount, number of types and complexity of clay coatings increased with depth. In the Bt horizons, we estimated the proportion of clay coatings to be 6%. Increasing contents of Al2O3, Fe2O3, MgO, K2O, Ba, Co, Cr, Ga, Ni, Sc, Th, U, V, Y and rare earth elements with increasing depth confirmed illuvial processes. Abrupt changes in clay content between the Bt and E horizons in some profiles indicate a possible contribution of allochthonous material or resedimented para-autochthonous material. Differences between soil materials are also indicated by geochemical indices calculated as ratios of selected elemental ratios Al2O3/TiO2, TiO2/Th, Rb/K2O, La/Hf, Th/Ni, Zr/Ni and Zr/Nb between successive horizons. The red soil also showed evidence of illuvial processes. The mineral and geochemical composition shows that the red soils are highly weathered, the most notable being the red soils in Bela krajina (Fed/Fet = 0.81). The soils on the plateau Kras are the reddest, although they contain less free iron oxide (Fed) than the soils in Dolenjska and Bela krajina, probably indicating different mineral carriers of iron. Despite the differences in the geochemical characteristics of the studied profiles, which are the result of different climatic conditions and different materials that contributed to the formation of the soils, we can conclude that eluvial-illuvial processes predominate in the soil pedogenesis of the Dinaric Karst, leading to the formation of illuvial soils, mostly with characteristics of the reference soil group of Luvisols.
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