Previous research of the geological evolution of Lake Balaton (Hungary) has been based on sporadic borehole data, evaluation of the topography of the surrounding regions, and water seismic data characterized by low horizontal resolution. The lake bed itself has been surveyed four times at regular intervals since 1895, but the latest complete survey was carried out in 1975 using the echosounding and optical geodetic methods of the time. In the framework of the cooperative efforts of the Eötvös Loránd University and Geomega Ltd, high resolution lakeseismic surveys were carried out on the Eastern Basin of the lake between 1997 and 2007. These provided precise and valuable data on the Pannonian strata overlain by Holocene sediments. The ultra-high resolution dataset made possible the determination of the water depth and the thickness of lacustrine sediments on a decimetre scale. A new digital elevation model of the lake bed was created for the Eastern embayment of the lake, together with the mapping of the Holocene sediment thickness and the erosion surface underneath. The calculated digital elevation model of the lake bed was compared to a model interpolated from the 1975 survey and thus the sedimentation rate could be calculated for the last 30 years. Although these surveys carry several possible sources of error, the calculated average deposition rate is in the same order of magnitude as the results acquired by previous authors using other methods. The present study also demonstrates that there are considerable differences in the sedimentation pattern and the differences show similarities with the topography of the discordance surface underlying the Holocene lacustrine sediment. The discordance surface separating the Pannonian and other pre-Holocene strata from the overlying Holocene lacustrine sediment shows a row of elevated features along the axis of the lake; these features have low slope angles towards the south and are relatively steep on their northern side. The line of this northern slope breaks in several places. There are no elements on the discordance surface surveyed which are similar to the meridional valleys of the areas to the south of the lake. The 30-year-scale lake bed changes, and the discordance surface of the lacustrine sediments and Pannonian strata also exhibit similarities with the characteristic directions of the surrounding topography. Thus they can partly be correlated with the previously documented neotectonic movements.
|Translated title of the contribution||Mapping bathymetry and thickness of lacustrine deposits of lake Balaton (Hungary), using lake seismic profiles|
|Number of pages||10|
|Publication status||Published - Dec 28 2010|
ASJC Scopus subject areas
- Geochemistry and Petrology