Gyula Gábris

Climate and tectonically controlled river style changes on the Sajó-Hernád alluvial fan (Hungary)

Abstract Based on geomorphological field investigations, sediment analysis, radiocarbon and palynological data, changes in fluvial style have been recognized on one of the most important low-angle fluvial-dominant alluvial fans on the margin of the Great Hungarian Plain (Hungary). Late Pleistocene and Holocene climatic and tectonic controls are reflected partly by meandering and anastomosed channel pattern changes, and partly by erosional step features on the cone that mark erosional and accumulational phases. This work has led to the surface mapping of a ‘horizontal stratigraphy’ as part of a larger research project in the Tisza region.

Fluvial and aeolian landscape evolution in Hungary - Results of the last 20 years research

Present study provides a review of the latest results on fluvial and aeolian landscape evolution in Hungary achieved by our team during the last 20 years. – The Hungarian river terrace system and its chronology was described with special emphasise on the novel threshold concept. A revised terrace system was created by the compilation of novel terrace chronology and MIS data. Evolution of river terraces was not only governed by climatic factors but tectonic ones too. Incision rate of the Danube, and uplift rate of the Transdanubian Range (TR) was around 0.1-0.3 mm/a in the marginal zones of the TR (mostly based on the published U-series data) and was above 1 mm/a in its axial zone (based on 3 He exposure age dating of strath terraces). – According to a detailed geomorphological investigation of the different channel-planform morphologies in the Middle Tisza region and Sajo-Hernad alluvial fan, six phases of river pattern change and four incision periods were detected during the last 20,000 years. – Wind polished rock surfaces dated by in situ produced cosmogenic 10 Be suggest that deflation was active in Hungary as early as 1.5 Ma ago. According to these exposure age data, Pleistocene denudation rate of the study area (Balaton Highland) was 40-80 m/Ma. – In sand covered areas the alternations of wind-blown layers and buried fossil soils provide information about climate and environment changes. In this study, periods of sand movement were mostly determined by optically stimulated luminescence (OSL) dating methods and five aeolian sand accumulation periods were recognised during the last 25 000 years. – A new loess stratigraphical view was elaborated using the most recent dating methods (luminescence, AAR). The lower part of Mende Upper (MF 1-2 ) pedokomplex is suggested to represent the last interglacial period (MIS 5e). During the last interglacial/glacial period (MIS 5 - MIS 2) several soil-forming periods existed but the preservation of these paleosoils is variable depending on their paleogeomorphological position.