The degree of aeolization of Quaternary deposits in Poland as a tool for stratigraphic interpretation

The aim of the study was to test if it is possible to distinguish Quaternary sediments hearing evidence of the impact of aeolian processes during their accumulation. It was also important to verify if distinguishing of these series would be useful in the accurate determination of stratigraphic position, determined previously using lithological, petrographic and palynological methods. The sediments were sampled from five boreholes, reaching the Tertiary, and from six exposures, all from Central, East and North Poland. The following features were taken to indicate a significant role of aeolian processes during sediment accumulation: high percentage of quartz grains (0.8-1.0 mm) in the sand fraction characterized by distinct rounding and frosting; high quartz content and low feldspar content (0.8-1.0 mm), and the composition of the heavy minerals fraction (0.1-0.2 mm). Garnets are particularly resistant to mechanical abrasion, whereas micaeous minerals are susceptible to winnowing. This spectrum of textural features, that indicates the effects of intensive aeolian processes, was termed deposit aeolization. Sediment aeolization may be observed in sediments of various origin: aeolian, fluvial or lacustrine. The study proved that the highest degree of aeolization occurred in alluvial (fluvioperiglacial) sediments accumulated before the first Riss (Odra) glaciation and in aeolian and fluvial sediments during the decline of Weichselian glaciation. Sediment aeolization is a valuable supplement to previous methods to indicate the stratigraphic position. The degree of aeolization allows the delimitation of the boundary between the Quaternary and Tertiary; it identifies glacitectonic and tectonic deformations; and it distinguishes fluvial and fluvioperiglacial sheets from fluvioglacial sheets. It is useful in estimating the length and intensity of aeolian processes; it adds to the interpretation of climatic conditions at the time of deposition and defines the limits of interglacial sheets within sandy sediments (30 to about 100 m thick) separating boulder clay units. (C) 2004 Elsevier B.V. All rights reserved.