Podzolization in aeolian sands, underlain by Gleysol formation, during nine millennia in southwestern Estonia

An outcrop of Carbic Podzol on aeolian sand, underlain by Molli-Histic Gleysol on calcareous till of the last glaciation, was studied on the bank of the Lemmejogi River, SW Estonia. Molli-Histic Gleysol at depths of 342-380 cm formed as a result of pedogenesis within the Younger Dryas-Pre-Boreal during about 1500-3200 years at an average accumulation rate of organic carbon of 5.3-2.5 g m-2 yr-1. The histic horizon formed during about 1000 years at a rate of 12-13 g m-2 yr-1 of organic carbon. Gleying of underlying till has led to slight textural changes but to some essential changes in mineral and chemical status. Gleysol was buried under the sediments of the Ancylus transgression about 9200-9000 years ago. Within the uppermost stratum, stratified sands have been reshaped by coastal winds after the retreat of the shoreline. Simultaneously with the development of the forest vegetation, pedogenesis started a little later than 9000 BP, and a unitary Carbic Podzol with the A-E-Bhs-Bs-BC-C sequence was formed. Organic C has accumulated at an average rate of 8.1 mg m-2 yr-1 cm-1 in the A-E-Bhs sequence, while the A- and Bhs-horizons were humus-accumulative and humus-illuvial in origin, respectively. Under the influence of R2O3- and/or Ca-fulvic humus, total cheluviation and formation of the albic horizon has proceeded at a rate of 55 μ m yr-1. The solum of 180 cm, formed during about 9000 years, represents the result of the weathering and podzolization of the initial sand column of 171 cm, while the upward expansion in the uppermost 75 cm progressed at a rate of 6-7 μ m-2 yr-1. As a consequence of interfraction changes, 5.6 g m-2 yr-1 of fine particles and 2.9 g m-2 yr-1 of chemical constituents have accumulated in the solum, although the A-E sequence is eluvial. Quartz and feldspars have mostly concentrated in fine sand. The increase in ore minerals and/or their eluvio-illuvial distribution has been induced by the weathering of pyroxenes and amphiboles. Against the background of total accumulativeness, the relationships of nonsiliceous substances are characterized by podzolic distribution. Due to human and some evident natural agents, a decrease in acidity and an increase in base exchange capacity and base saturation have taken place in the A-E-Bhs sequence of Carbic Podzol.