Status and development of deep geological repository in Slovak republic from geological point of view

During the operation of Slovak NPPs, production of approximately 2,300 metric tons of spent fuel expressed as heavy metal (18,654 spent fuel assemblies) is expected. In addition, about 5000 metric tons of radioactive waste unfit for near surface repository at Mochovce and destined for a deep geological disposal. The safe and long-term solution of back-end fuel cycle is so highly required.One of the most favorable solutions is Deep Geological Repository (DGR). The site for a DGR, along with repository design and the engineered barrier system must ensure long-term safety of the disposal system.A preliminary set of site-selection criteria for a DGR was proposed in Slovakia, based on worldwide experience and consistent with IAEA recommendations. Main groups of criteria are: 1) geological and tectonic stability of prospective sites; 2) appropriate characteristics of host rock (lithological homogeneity, suitable hydrogeological and geochemical conditions, favourable geotechnical setting, absence of mineral resources, etc.); 3) conflict of interests (natural resources, natural and cultural heritage, protected resources of thermal waters, etc.).Based on the previous geological investigations, three distinct areas (five localities) were determined as the most prospective sites for construction of a DGR so far. Three of them are built by granitoids rock (Tribeč Mts., Veporske vrchy Mts. and Stolicke vrchy Mts.), other consist of sedimentary rock formations (Cerova vrchovina Upland and Rimavska kotlina Basin). Objective for the next investigation stage is to perform more detailed geological characterization of the prospective sites

Deep contact of the Bohemian Massif and Western Carpathians as seen from density modeling

Density modelling was carried out along five profiles oriented across the expected deep contact between the Bohemian Massif and the Internal Western Carpathians in western Slovakia. The density models reveal the continuation of the Bohemian Massif beneath the External and Internal Western Carpathians tectonic units. The eastern margin of the Bohemian Massif is situated at depth south-east of the surface outcrops of the Pieniny Klippen Belt and changes its position in the surveyed area. The contact of the Internal Western Carpathians with the Bohemian Massif and External Western Carpathians is subvertical. This sharp contact is manifested as the transtension to extension zone towards the surface

The Alpine tectonic evolution of the Danube Basin and its northern periphery (southwestern Slovakia)

The tectonic evolution of the pre-Cenozoic basement, as well as the Cenozoic structures within the Danube Basin (DB) and its northern periphery are presented. The lowermost portion of the pre-Cenozoic basement is formed by the Tatricum Unit which was tectonically affected by the subduction of the Vahicum / Penninicum distal continental crust during the Turonian. Tectonically disintegrated Tatricum overlaid the post-Turonian to Lower Eocene sediments that are considered a part of the Vahicum wedge-top basin. These sediments are overthrust with the Fatricum and Hronicum cover nappes. The Danube Basin Transversal Fault (DBTF) oriented along a NW–SE course divided the pre-Neogene basement of the DB into two parts. The southwestern part of the DB pre-Neogene basement is eroded to the crystalline complexes while the Palaeogene and Mesozoic sediments are overlaid by the Neogene deposits on the northeastern side of the DBTF. The DBTF was activated as a dextral fault during the Late Oligocene – Earliest Miocene. During the Early Miocene (Karpatian – Early Badenian) it was active as a normal fault. In the Middle – Late Miocene the dominant tectonic regime with NW – SE oriented extension led to the disintegration of the elevated pre-Neogene basement under the simple and pure shear mechanisms into several NE – SW oriented horst and graben structures with successive subsidence generally from west to east. The extensional tectonics with the perpendicular NE – SW orientation of the Shmin persists in the Danube Basin from the ?Middle Pleistocene to the present

Pliocene to Quaternary stress field change in the western part of the Cen tral West ern Carpathians (Slovakia)

Knowledge of the current tectonic regime plays an essential role in natural hazard assessment, especially in the risk assessment of fault activity. Structural analysis of brittle deformations (using in version techniques) was used to determine the stress field state occurring within Pliocene and Quaternary deposits in the western part of the Central Western Carpathians. The deformation pattern of the reduced stress tensor showed that all structural measurements could be separated into two groups. An older, Late Pliocene fault population was activated un der NNW-SSE oriented extension. A younger, Quaternary fault population reflected origin in a NE–SW extensional tectonic regime and it distinctly showed a change the orientation of the S3 of about 70. The change in tectonic activity, as well as in the stress field orientation, is dated to the Pliocene-Pleis to cene boundary. The Quaternary stress field developed dur ing the post-collisional stage of the orogen. Our study shows that the West ern Carpathian internal units document NE-SW to NNE-SSW extension in the broader region around of the north ern Danube Basin

The Lithospheric structure of the Western Carpathian-Pannonian Basin region based on the CELEBRATION 2000 seismic experiment and gravity modelling

The lithospheric structure of the Western Carpathian–Pannonian Basin region was studied using 3-D modelling of the Bouguer gravity anomaly constrained by seismic models and other geophysical data. The thermal structure and density distribution in the shallow upper mantle were also estimated using a combination of petrological, geophysical, and mineral physics information (LitMod). This approach is necessary if the more complicated structure of the Pannonian Basin is to be better constrained. As a result, we have constructed the first 3-D gravity model of the region that combines various geophysical datasets and is consistent with petrological data. The model provides improved estimates of both the density distribution within the lithosphere and the depth to major density discontinuities. We present new maps of the thickness of major sedimentary basins and of the depth to the Moho and the lithosphere–asthenosphere boundary. In our best-fitting model, the Pannonian Basin is characterised by extremely thin crust and lithospheric mantle, both of which have low density. A low-density uppermost asthenospheric mantle layer is also included at depths of 60–100 km. The Western Carpathians have only a thin crustal root and moderate densities. In contrast, the European Platform and Eastern Alps are characterised by lithosphere that is considerably thicker and denser. This inference is also supported by stripped gravity anomalies from which sediment, Moho and asthenospheric gravity contributions have been removed. These residual anomalies are characteristically low in the Western Carpathian–Pannonian Basin region, which suggests that both the ALCAPA and Tisza–Dacia microplates are ‘exotic terranes’ that are markedly different to the European Platform.16 page(s

Cretaceous—Quaternary tectonic evolution of the Tatra Mts (Western Carpathians): constraints from structural, sedimentary, geomorphological, and fission track data

The Tatra Mts area, located in the northernmost part of Central Western Carpathians on the border between Slovakia and Poland, underwent a complex Alpine tectonic evolution. This study integrates structural, sedimentary, and geomorphological data combined with fission track data from the Variscan granite rocks to discuss the Cretaceous to Quaternary tectonic and landscape evolution of the Tatra Mts. The presented data can be correlated with five principal tectonic stages (TS), including neotectonics. TS-1 (~95-80 Ma) is related to mid-Cretaceous nappe stacking when the Tatric Unit was overlain by Mesozoic sequences of the Fatric and Hronic Nappes. After nappe stacking the Tatric crystalline basement was exhumed (and cooled) in response to the Late Cretaceous/Paleogene orogenic collapse followed by orogen-parallel extension. This is supported by 70 to 60 Ma old zircon fission track ages. Extensional tectonics were replaced by transpression to transtension during the Late Paleocene to Eocene (TS-2; ~80-45 Ma). TS-3 (~45-20 Ma) is documented by thick Oligocene-lowermost Miocene sediments of the Central Carpathian Paleogene Basin which kept the underlying Tatric crystalline basement at elevated temperatures (ca. > 120 °C and < 200 °C). The TS-4 (~20-7 Ma) is linked to slow Miocene exhumation rate of the Tatric crystalline basement, as it is indicated by apatite fission track data of 9-12 Ma. The final shaping of the Tatra Mts has been linked to accelerated tectonic activity since the Pliocene (TS-5; ~7-0 Ma)

A seismic source zone model for the seismic hazard assessment of Slovakia

We present a new seismic source zone model for the seismic hazard assessment of Slovakia based on a new seismotectonic model of the territory of Slovakia and adjacent areas. The seismotectonic model has been developed using a new Slovak earthquake catalogue (SLOVEC 2011), successive division of the large-scale geological structures into tectonic regions, seismogeological domains and seismogenic structures. The main criteria for definitions of regions, domains and structures are the age of the last tectonic consolidation of geological structures, thickness of lithosphere, thickness of crust, geothermal conditions, current tectonic regime and seismic activity. The seismic source zones are presented on a 1:1,000,000 scale map

Lithosphere in the Western Carpathians and its surrounding tectonic units - Geophysical study

Geophysical methods are important tools for the investigation of the structure and geodynamic development of the lithosphere. The central and eastern parts of the Western Carpathians are bordered in the north by a thicker  and stronger lithosphere of the European platform (100-150  km), which is underthrust (about of 50 km) beneath the margin of the overriding Carpathian orogen. This thickening is interpreted as remnants of subducted slabs. In contrast, the “thin” lithosphere at the western margin of the Western Carpathians can be considered as a result of oblique collision along a deep-seated transform zone between the platform and orogenic lithosphere. Neo-Alpine “soft” collision and retreating subduction of this orogen can also be discovered by means of quantitative interpretation of observed gravity field. The crustal thickness in the Western Carpathians ranges among 27-35 km. The central Western Carpathians are characterized by thicker crust (30-55 km) in comparison with thinner crust (25-30 km) in the Pannonian Basin System. This feature is probably the result of the youngest lithosphere processes from the Middle Miocene. Rheological properties of the Western Carpathian lithosphere show that the mechanical strengths decrease within the whole lithosphere from the area of the European platform via the Western Carpathians to the Pannonian Basin. The most remarkable and important first-order tectonic structures (seismo-tectonic zones) in  the Western Carpathians are the zones of the Pieniny Klippen Belt, the Mur-Mürz-Leitha fault zone, the Čertovica fault zone and the Hurbanovo line. Map of neo-Alpine fault systems and neotectonic regions (blocks) of  Slovakia was defined

Integrated interpretation of geophysical fields - Implications for the tectonic structure of the Mochovce nuclear power plant

The contribution contains of the geophysical data and their interpretation. Interpretation of geophysical fields in compliance with the geological structure and geodynamics EMO far region contributes significantly to development of  seismo-tectonic model. The model represents the correlation between seismic activity and geological-tectonic setting. The achieved seismo-tectonic model in fact reasons all recorded seismic events in the area and points out to a seismic activity decrease towards the Danube Basin center,  thereof, there being situated the EMO locality