Late Pleistocene pedogenesis response to millenial-scale climate variability: Evidence from the Volyn sequences (NW Ukraine)

Abstract

High-resolution loess-palaeosol sequences are valuable terrestrial archives for studying millenial palaeoclimate variations. They are rarely encountered or insufficiently studied in the transitional zone between Central and Eastern Europe, where the loess-palaeosol sequences were sensitive to short-term changes in both the oceanic and continental climate sub-systems. As a result, only little is known about short-term changes in pedogenesis and abrupt pedosedimentary events in this transitional area. To fill this gap in our knowledge, this study provides the new stratigraphic, micromorphological, grain-size and geochemical investigations of the Volyn loess-palaeosol sequence (NW Ukraine). Due to the accretionary nature of palaeosols, the Volyn sequence has a high-resolution, allowing to refine the evolutionary scheme of Late Pleistocene pedogenesis in the Northern European loess belt. The sequence consists of the MIS 5 pedocomplex (P1) and an overlying loess unit (L1) with three palaeosols. A thin humified soil, overlying the Eemian Luvisol, indicates an aridity pulse at the end of MIS 5e. The Early Glacial soils show their accretionary nature due to aeolian sand contribution to pedogenesis, which resulted in up to 5 individual soils indicating different interstadials. The oldest MIS 5c soil show clear evidence of clay illuviation during the warm and humid interstadial, whereas the other soils have well-expressed mollic horizons, indicating the significant aridification trend towards the end of MIS 5. The Middle Pleniglacial soil (Dubno unit, correlative of MIS 3) in the most complete sequences turns into three soils: warmer interstadials are represented by Cambisols, whereas colder ones by Gleysols. The two youngest Gleysols (Rivne and Krasiliv units) in the most complete sections are bipartite, indicating early hydromorphic and late xerymorphic phase of pedogenesis. Finally, the Volyn loess-palaeosol sequence provides an important information on abrupt pulses of aeolian sedimentation (local sand and regional dust), which indicate that dust/sand deposition did not cease during the interstadials.