Mineralogical study on a landslide in the area of Kulcs, Hungary Meetings of Young Scientists Békéscsaba 2013 Mineralogical study on a landslide in the area of Kulcs, Hungary Beatrix Udvardi1, 2, István Kovács1, Judit Füri1, Péter Kónya1 1 Lithosphere Fluid Research Lab, Department of Petrology and Geochemistry, Eötvös University 2 Geological and Geophysical Institute of Hungary

Landslides occurring more often due to the changing pattern of precipitation!

Motivation and rationale What is new and complementary in our approach with respect to previous studies? -sampling the vicinity of the supposed sliding zone of a major known landslide -complex analytical investigation (XRD, DTA and FTIR-ATR) of minerals in the vicinity of the sliding zone (previously due to mainly financial reasons and limited time allocation only grain size distribution was determined). -Is there a mineralogical, geochemical precursor behind the occurrence of landslides or it is only due to the preexisting sedimentary features or both?

Study area 50-70 m above the average water level of Danube Resort area from 1920, densely built since 1960 on the debris No appropriate drainage and sewage system After Újvári et al, 2009 Continuously moving area: first notable sliding event in 1977, last one in 2013 Partial rebuilding in 2010

Field observations 28/02/2013 04/10/2012 06/05/2012

Sampling Northing Easting Boreholes in the upper part of the sliding mass: C9, C10, C11, C11-1 (Farkas, 2011)- sliding zone was found at -8,30 (C10- 113mBf) and -3,3 (C9-93 mBf) in the high bluff

Results - Sedimentology K4 K3 Rapid changes in the sediment structure, sand bands

Results - Mineralogy Minerals (XRD) % montmorillonite 0-32 illite 0-25 muscovite 0-20 kaolinite 0-3 chlorite 5-16 quartz 17-62 K-feldspar 1-3 plagioclase 0-8 calcite 0-43 dolomite 0-30 goethite 0-4 gypsum 0-1 amorphous 0-5 sheet silicates 17-68

Results – Mineral distribution vs. depth Corrected depth according to the theodolite measurements

Results - Clay mineral composition (settled samples) Minerals (XRD) % montmorillonite 3-65 illite 0-69 Illit/chlorite 0-18 muscovite 0-52 kaolinite 0-15 chlorite 0-40

Results - Clay mineral composition in settled samples

Results - IR depth profile K3

Results - IR depth profile K4

Results- Calcite dissociation ΔT=0; characteristic thermal dissociation peak of well crystallized calcite (at 895°C) The temperature of calcite with lower crystallinity is lower about 20-50 °C that of the well crystallized variation (Földvári, 2011 )

Summary Following field observations phase analysis (XRD, DTA and FTIR-ATR) were carried out on samples coming from 6 boreholes (n=46), that was drilled at the toe of a partially cultivated landslide body in Kulcs to reach and samples the sliding zone. A distinct zone in mineral composition was clearly identified in the following depth range 1,4-2,4 m and 1,2-2,1 m in two boreholes. This zone is under a grey silt horizon, where elevated clay mineral content and low carbonate content was revealed The preliminary results indicate that underground water flow and its interaction with sediments may play an important role in the formation of clays and dissolution of carbonates which can contribute to the weakening It seems that mineralogical study of landslides could contribute to the identification of sliding zone FTIR-ATR may be a useful complementary tool to identify zone in sedimentary succession which may act as weakness zones

Thank you for your attention! Acknowledgement Tamás Fancsik, József Vatai, Villő Deák, Balázs Füsi, László Koloszár, Viktor Hermann, András Németh, Géza Kutasi, Péter Nagy, Csaba Jerabek, Éva Pálfi, Ferenc Budai (Geological and Geophysical Institute of Hungary) Csaba Szabó (Eötvös University) Judith Mihály, Csaba Németh (Hungarian Academy of Sciences) Lithosphere Fluid Research Lab (LRG) This study was supported by a Marie Curie International Reintegration Grant (NAMS-230937) (IK) Thank you for your attention!

Field observation 09/10/2012 28/02/2013

Landslides along Danube loess bluff Mass movements has appeared on the high bank of Danube since the Roman times Objective: observe slip zone in the river bank through sediment structure and mineral composition to distinguish discontinuities in the area of Kulcs water level of the Danube 20-80 m thick loess underlaid by Pliocene-Pannonian clay, silt and sand previous mass movements slope gradient High precipitation events groundwater level Slip surface/zone formation induced by: After Újvári et al, 2009 Causes +steeping the slope (due to construction, addition of high mass material on a slope (buildings), no drainage, broken pipes After Karácsonyi & Scheuer, 1972

Stabilization of landslide areas Create a free outflow to collect groundwater behind the soil volume fallen down – well system Deep long drainage system into the permeable soil layer Reconstruction of the original soil surface Remove the slipped soil volume Soil anchor system Vegetation Szemesy, I. 2011