Paper No. 4
Presentation Time: 1:30 PM-4:30 PM
CHANGES IN QUATERNARY FLUVIAL TRANSPORT DIRECTIONS TO MID-HUNGARIAN PLAIN, BASED ON STATISTICAL ANALYSIS OF DETRITAL HEAVY MINERAL COMPOSITION OF SANDS
THAMÓ-BOZSÓ, Edit1, LAJOS, Ó. Kovács
2 and KERCSMÁR, Zsolt
1, (1)Basin Analysis, Geological Institute of Hungary, Stefánia 14, Budapest, 1143, Hungary, (2)Information Centre, Hungarian Geological Survey, Stefánia 14, Budapest, 1143, Hungary, bozso@mafi.hu
Quaternary fluvial sediments in the central part of the Hungarian Plain (Pannonian Basin) have been studied in 10 cored boreholes. The 50-690 m thick sediment successions consist of sand, silt and clay, transported here from different directions. Recently the Tisza River and its tributaries bring pyroxene, hornblende, epidote, chlorite or garnet rich sediments from NE, NNE and SE directions into the studied area, from the Apuseni Mountains and the NE-Carpathians, while Danube River brings here sediments with high garnet content from NW direction, mainly from the Alps and from the W-Carpathians.
The evaluated mineralogical data derive from earlier examinations by polarising microscope of the 0.1-0.2 mm fraction of 590 sand samples from the boreholes and from recent river sediments of the Hungarian Plain. Based on the similarities between the detrital heavy mineralogical composition of samples derived from recent river sediments and from boreholes, revealed by Cluster Analysis and Principal Component Analysis (PCA), we can reconstruct the paleo-fluvial transport directions and provenance, as the geological and geographical constraints of the region have been similar during the Quaternary. With these methods in most cases we could distinguish the sediments of the Paleo-Tisza River and its tributaries, from the sediments of the Paleo-Danube River. The suggested separation has some uncertainties when sediments of different rivers have similar heavy mineral suites, although the geological settings of the catchments of these two main rivers are quite different.
Changes in fluvial transport directions and river pattern during the Quaternary reflect tectonic changes: the uplift of the surrounding mountains and different part of the Hungarian Plain, and local subsidence of certain areas.
This research was supported by the Hungarian National Scientific Research Fund (OTKA T-32956).
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