Šujan M. & Rybár S., 2014: The development of Pleistocene river terraces in the eastern part of the Danube Basin. Acta Geologica Slovaca, 6, 2, 107–122. (in Slovak with English summary)

Vývoj pleistocénnych riečnych terás vo východnej časti Dunajskej panvy

The development of Pleistocene river terraces in the eastern part of the Danube Basin

Michal Šujan & Samuel Rybár

Katedra geológie a paleontológie, Prírodovedecká fakulta, Univerzita Komenského v Bratislave, Mlynská dolina, 842 15 Bratislava; miso@equis.sk

Abstract

Spatial distribution of fluvial sediments in the Hron Upland area situated at the eastern part of the Danube Basin was investigated in purpose to reconstruct Pleistocene river basin development. The distribution of river accumulation terraces was detected on the basis of a database of 1900 wells. Base level of the terraces, interpolated for two sub-areas, was the main tool for distinguishing terrace levels. The interpolation was controlled with spatial autocorrelation analysis using Moran’s I method. Three terrace systems of rivers paleo-Hron, paleo-Žitava and paleo-Danube were identified, different in geometry, layout of the terraces and petrography of the sediment. The paleo-Hron terrace system consists of six wide north-south oriented levels retreating to the east, while terraces of paleo-Žitava are only erosive remnants of four levels retreating to the northwest. Two levels of the paleo-Danube terrace system are situated in the southern part of the researched area, oriented in west-east direction. Accumulation of the terraces started on the Pliocene-Pleistocene boundary, what is indicated by fossil mammals found in the highest terrace levels. Asymmetric uplift of the Hron Upland area reached its maximum in the south, in the Transdanubian Range Mts. realm. In the study area it reached 80 m, with average movement velocity of 0.03 mm.a^-1. Uplift formed first separate river basins of the paleo-Hron and paleo-Žitava in Lower Pleistocene, followed by shift of paleo-Danube to the studied area during the Midle to Upper Pleistocene. The riverbed (channel) dynamics was connected with strong erosion together with incision into the Danube Bend Gate. Brittle tectonics influenced the terrace levels negligible, an exception being the paleo-Danube terrace in the south with 10 to 15 m offsets of normal faults.

Key words: Western Carpathians, Danube Basin, Pliocene, Quaternary, river terraces

Manuscript received: 2014-01-19

Revised version accepted: 2014-04-23