Likhvin interglacial polygenetic paleosol: A reconstruction on the Russian Plain

The older, interglacial optimum phase of the IPP (Phase A) features changes from north to south as does the modern-day soil in the same geographical area, although soil zones of the optimum are shifted slightly southward relative to present-day soil zones. Albeluvisols reconstructed on the north of the study area develop into Cambisols/Luvisols/Phaeozems in the central part of the area and into Chernozems further southward. It appears that climatic conditions during paleosol formation were more humid than at present. The younger, post-optimal phase of the IPP (Phase B) is identified as an accretionary Humic Regosol on the central Russian Plain, but developed into Chernozems southward. The Phase B soil zonation is simplified in comparison with present-day one and, tentatively, corresponds to interstadial conditions. Therefore, spatial changes in the IPP features indicate that zonal structure of environment developed along the Russian Plain at least as early as the Middle Pleistocene Likhvin Interglacial.