Geochemical characterization and origin of Southeastern and Eastern European loesses (Serbia, Romania, Ukraine)

Abstract

The loess/paleosol sections of Batajnica/Stari Slankamen (Serbia), Mircea Voda (Romania) and Stary Kaydaky (Ukraine) were geochemically characterized based on discriminant analysis of major and trace elements, the ratios of Al/Ti, Fe/Ti and Al/Fe, the A-CN-K ternary plot and element enrichment/depletion relative to the average composition of the upper continental crust. The origin of the loess material in the southern Pannonian Basin (Vojvodina), the lower Danube Basin/Dobrudja and the Dnieper area was evaluated by comparison with the representative element composition of possible source areas and by considering the geomorphodynamic setting. Also the background values of the initial magnetic susceptibility of the loesses were taken into account. For the lower Danube Basin, Dobrudja and the Ukraine, paleowind direction was reconstructed based on the geographic distribution of sandy soil texture and dunes related to river systems. Finally, loesses were evaluated as possible samples of the average upper continental crust. Our results show that Danube and Dnieper loess areas can be clearly distinguished. The former reveal higher Al and Fe contents, the latter higher Si, Zr, Hf content and indications of effective mineral and grain size sorting. We can confirm that Vojvodina loess originated from Danube alluvial material and loess of the Dnieper area from glaciofluvial sediments of the Fennoscandinavian ice sheet. The Dobrudja loess derived also predominantly from Danube alluvium, but shows significant contribution of a second loess source, probably the glaciofluvial sediments of the Ukraine. This was forced by northerly katabatic winds from the Fennoscandinavian ice sheet, whereas WNW winds prevailed in the Western Walachian plain. The studied loesses reflect the average composition of the upper continental crust. Yet, biases exist due to selective mineral/element enrichment and depletion in the course of previous sedimentary recycling phases, respectively. Material of all studied loess deposits seems to derive originally from sedimentary rocks.