ИСТИНА

Many soil properties that are preserved in buried soils of archaeological sites are associated with particular type of environmental conditions and thus carry paleoenvironmental signatures. Visual observation of pedofeatures, however, provides insufficient information on the soil processes and therefore the integrated analysis including application of analytical methods is needed for their better interpretation. This study presents the results of a geochemical study of two nearly 2m deep morphologically similar soils which were formed on the same surface and in close proximity to each other at the Nozha-Var archaeological site, located at the northern boundary of the forest-steppe zone in European Russia. The study objects included a paleosol buried 2000-1400 cal yr BP (Early Iron Age) under a fortification earth wall of an ancient settlement and the off-site surface soil. Concentrations of major and trace elements were determined in the bulk soil samples (n=29) and also in the soil clay-particle fraction (n=15) by XRS method after loss on ignition determination (1000ºC). Data on the ratios of relatively immobile elements (Ti/Al, Ti/Zr, Zr/Y, Zr/Nb) were used to evaluate the geochemical uniformity of the parent materials in which the soils were formed. The similarity between the soils according to the parameters’ values and also the absence of abrupt changes in their depth functions were found. This allows for relating the possible differences in the soil geochemistry to either environmental changes or duration of pedogenesis. Both morphological and analytical features confirmed that the studied soils meet diagnostic criteria for Retisols and have a similar textural contrast between the upper (Ah, E) and middle (Argic) horizons. However, the surface soil showed better expressed retic properties which were in line with higher molar SiO2/Al2O3 ratio both in the bulk samples and also in the clay-sized fraction. The distribution of element concentrations in the clay-particle fraction across soil horizons indicated better development of eluvial and leaching processes in the surface soil: in its upper horizons (Ah, E, E/Bt) the clay was clearly depleted in Fe2O3, Al2O3, CaO. In the Argic horizons of both soils the clay-sized fractions showed similar geochemical patterns. Thus, geochemical characteristics of the studied soils proved that they experienced one-way evolution and the geochemical differences between them seem to be related to the duration of pedogenesis.