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György Varga, University of Pécs (Hungary)
Zsolt Berta, MECSEKÉRC Environmental Protection Plc. (Hungary)
József Csicsák, MECSEKÉRC Environmental Protection Plc. (Hungary)
Amadé Halász, University of Pécs (Hungary)
Gábor Hámos, MECSEKÉRC Environmental Protection Plc. (Hungary)
Gyula Konrád, University of Pécs (Hungary)
László Kovács, Kútfej Co. (Hungary)
György Majoros, MECSEKÉRC Environmental Protection Plc. (Hungary)
Zoltán Máthé, MECSEKÉRC Environmental Protection Plc. (Hungary)
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Safe disposal of spent fuels and high level nuclear wastes requires widespread and considered research also in Hungary. Beside of the general information needs of a site selection and characterization program, special attention has to be paid to the Neogene tectonic activity of the Carpathian Basin. As outcome of this, the 800-1000 m thick Boda Claystone Formation (BCF) from southern Hungary was proved to be worthy for further research. This poster presents the foregoing research. The outcrops of BCF are connected to the peri-anticlinal structure of W Mecsek Mts. Northward and eastward it is getting deeper, eroded on the west side and thin out tectonically on the southern side. The anticline structure is affected by the Cretaceous orogeny and is bounded to the south by left-lateral strike-slip fault. The Mecsek Mts. show a palm-tree structure of a shear zone. The investigated formation is in the middle of this shear zone. The hydrogeology is also important next to the tectonics, because the overlying karstifiable limestone strata which is underlain by a 1500 m thick sedimentary succession as an interval-zone. The BCF is overlain by the Kővágószőlős Sandstone Formation which contains uranium deposit mined during 50 years. The uranium ore exploration and mining provided hugh amount of data for the characterization program. The first phase of the research was developed on these data. Based on geological mapping, drilling, geophysical survey, geodynamical and geotechnical measurement, hydrogeological monitoring; furthermore in situ observation in an exploratory tunnel at 1100 m depth in the mine, we know more about the extension, facies, lithological, geomechanical and geochemical characteristics of the formation. This sediment was deposited in a rifting basin on the southern margin of the Permian Europe. It is underlain by an extensive rhyolite volcanic succession (Gyrf Rhyolite) that indicates continental rifting. Intramontane basin was developed with playa lakes in arid climatic condition. Mainly aeolian deposit was accumulated. Granite and rhyolite were the area of provenance, thus "Lake Natron-kind" chemical environment was formed. The oxidation state of iron, the repeated desiccation cracks, the occurrence of analcime and its diagenetic albitic form, all reflects the depositional environment. The cycles of the sequence are connected to climatic events. Due to progressive subsidence (6000 m), the sediment was turned to claystone (aleuritic claystone, argillaceous/clayey aleurite, albitic claystone, albitolite). The claystone body is crushed in a different extent, affected by the Cretaceous and Neogene orogenic movements. The primary permeability of the claystone is very low according to closed fractures and swelling clay minerals. The tectonic blocks inside the known deposit area show homogeneous uplift. According to all, the research is in progress, next aim is the selection of the underground exploratory laboratory location.
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