Record of aeolian processes in Pleistocene deposits in the foreland of the European sand belt

Abstract

Abstract This article presents the degree of aeolization of Pleistocene deposits in the foreground of the European sand belt in southern Poland. Ten of the 13 sites were established in the Oświęcim Basin and three in the south part of the Silesian Upland. Attention was focused on four types of deposits formed during three glaciations (Sanian, Odranian, Vistulian): boulder clay, fluvioglacial sands and gravels, end moraine deposits, and aeolian sands. Quartz grain abrasion (for the 0.8–1.0 mm fraction) was examined by mechanical graniformametry and the morphoscopic method. The record of aeolian processes in analyzed deposits is the presence of quartz grains RM (very well-rounded and mat) and EM/RM (moderately rounded and mat). They were found in deposits of various origins and ages but in variable proportions. Considering only the average percentage of grains RM, it should be regarded that abrasion of deposits is low in the case of fluvioglacial deposits, moderate in the case of glacial deposits, and good in the case of aeolian deposits. However, the key factor in determining the degree of abrasion is the share of EM/RM grains, which in the abovementioned deposits are seven, three, and twice as many as RM grains. Therefore, the most noteworthy research result is the very high total share of grains with aeolian abrasion (RM + EM/RM), amounting on average to 84.1% for Odranian fluvioglacial deposits, 86.7% for Sanian glacial deposits and 92.6% for Late Glacial aeolian deposits. It means that in the study area, glacial and fluvioglacial transport included deposits with good aeolian abrasion obtained in the periglacial environment before the transgression of the ice sheets. Probably due to the longer persistence of periglacial conditions in southern Poland, compared to its central and northern parts, the degree of aeolization of fluvioglacial and glacial deposits is better. At the same time, there is a significant differentiation in the aeolization of fluvioglacial deposits within the outwash plain in the foreland of the maximum extent of the Odranian ice sheet. In its proximal part, near the front of the ice sheet, fluvioglacial deposits are characterized by much worse abrasion of quartz grains than in the distal part.