Sedimentary characteristics and source of loess in Baranja (Eastern Croatia)

Abstract

Abstract Loess is a type of terrestrial clastic sediment formed by the accumulation of wind-blown dust, composed dominantly of silt-sized particles. It is usually inter-bedded with soil horizons forming loess–palaeosol successions (LPS). The thickest LPS in Croatia are found in Baranja, a region bounded by two large rivers, the Danube and the Drava. The results of grain-size and modal analysis provide information about source material and wind direction in different time periods during the Pleistocene. Grain-size distribution is in good accordance with other loess localities in the Pannonian Basin. Garnet, epidote and amphibole are the most abundant heavy minerals in samples of Danube river sediment. The comparison of heavy mineral assemblages (HMF) from LPS with that of the Danube river, shows that the main source area for loess in Baranja was in the Danube flood plain sediments. Main transport direction was from North or Northwest. Nevertheless the higher concentration of amphiboles in LPS (mean 26.3% in HMF) than in the Danube plain suggests an additional source area. Although the Western Carpathians with Neogene calc-alkaline volcanic rocks are the major source for amphiboles in the Pannonian Basin, those minerals may partly originated also from locally exposed volcanic and metamorphic rocks of the southward Slavonian Mountains. Mount Krndija and Mount Papuk, which of all Slavonian Mts. are closest to Baranja, consist indeed of amphibolites. In that case, a small amount of silt material for Baranja loess would be transported by WSW winds. Results obtained from sedimentological and SEM analyses show fairly good congruence with results from other LPS in the Pannonian Basin, with some differences in mineral composition which imply diversity and shifting of source area for Baranja loess during the Late Pleistocene.