Middle to late Pleistocene uplift rate of the Hungarian Mountain Range at the Danube Bend, (Pannonian Basin) using in situ produced 3He

Topography of the terraced Danube Bend area indicates fast incision of the Danube River, which was followed by its tributaries dissecting deeply the former terrace levels. These surfaces are vertically bended along the river course, indicating antecedent incision of the Danube into the SW-NE trending Hungarian Mountain Range (HMR). Timing and rate of the incision of the Danube into the HMR and consequently, the rate of vertical motions have remained unresolved so far. This study aims at quantifying the landscape evolution and neotectonic deformation of the central part of the HMR. We used terrace levels along the antecedent section of the Danube River to constrain its incision rate, which is a measure for the uplift rate of the HMR. Here we use He-3, a terrestrial in situ produced cosmogenic nuclide (TCN), to date uplifted geomorphologic levels along in the Danube Bend gorge. This method, first applied in the Carpathian-Pannonian system in the framework of present study, proved to be suitable for the quantification of landscape evolution in this area. Our He-3 exposure age data suggest a maximum incision rate of similar to 2.7 +/- 0.1 mm/y for the last similar to 170 ky. Considering likely effect of erosion a more conservative value of similar to 1.6 mm/y for the last similar to 270 ky, was obtained. Both rates are significantly higher than the incision rate of 0.41 mm/y of the Danube derived from previous geologic and geomorphic data for the last 360 ky. The formation of the terrace levels in the Danube Bend probably occurred during the last two glacial cycles (OIS 1-8). According to the exposure age data, there is no direct relationship between the terrace formation and climate in the Danube Bend. Incision of the Danube appears to be connected to the uplift of the HMR, obtained incision rate values can be taken as valid approximations of the uplift rate in the Danube Bend area. (c) 2005 Elsevier B.V. All rights reserved.