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Three-dimensional ambient noise tomography of the Bohemian Massif
Valentová, Ľubica ; Gallovič, František (advisor) ; Burjánek, Jan (referee) ; Kristek, Jozef (referee)
We have performed 3D ambient noise tomography of the Bohemian Massif. We invert adopted inter-station dispersion curves of both Love and Rayleigh waves in periods 4-20 s, which were extracted from ambient noise cross-correlations, using a two-step approach. In the first step, the inter-station dispersion curves are localized for each period into the so-called dispersion maps. To account for finite-frequency effects, gradient method employing Fréchet kernels is used. Assuming membrane wave approximation of the surface wave propagation at each period, the kernels were calculated using the adjoint method. To reduce the effect of data noise, the kernels were regularized by Gaussian smoothing. The proper level of regularization is assessed on synthetic tests. In the second step, the phase-velocity dispersion maps are inverted into a 3D S-wave velocity model using the Bayesian approach. The posterior probability density function describing the solution is sampled by more than one million models obtained by Monte-Carlo approach (parallel tempering). The calculated variance of the model shows that the well resolved part corresponds to the upper crust (i.e., upper 20 km). The mean velocity model contains mainly large scale structures that show good correlation with the main geologic domains of the Bohemian...
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Late Cenozoic response of the selected fluvial systems of the Bohemian Massif to tectonics.
Flašar, Jan ; Martínek, Karel (advisor) ; Pánek, Tomáš (referee) ; Moreiras, Stella Maris (referee)
Despite its intraplate tectonic setting, the Bohemian Massif underwent relatively intense tectonic activity during the Cenozoic. This activity has significantly formed the terrain morphology and river geometry, which can easily be observed from the present status of the streams and relief. Although the effect of tectonics and climate on the terrain morphology has been already researched in previous studies, the effect on the geometry of the river systems has not been surveyed complexly. The author's previous master thesis found two remarkable areas within the Bohemian Massif, where the effect of climate and tectonics on the river system geometry and its changes is very probable - the area of western Bohemia along the Mariánské Lázně Fault and the area of the Novohradské hory Mountains and their foothills. The focus of this thesis is to study the mutual interactions between the tectonic activity and the geometry of selected river systems in the Bohemian Massif. The goal is not only to prove the connection but also to test and evaluate the set of methods that can be useful for localizing those places with recent tectonic activity and which can be applied in similar areas in the future. Both areas - along the Mariánské Lázně Fault and in the Novohradské hory Mts. and their foothills - were surveyed by...
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Use of rock mass classifications for rock fall susceptibility analysis in the conditions of the Bohemian Massif
Racek, Jonáš ; Blahůt, Jan (advisor) ; Petružálek, Matěj (referee)
This thesis deals with rock mass classification systems. The aim of the thesis is to describe and compare selected systems and evaluate their possible use in the Bohemian Massif for assessing the stability of the rock slopes in relation to their susceptibility to rock falls. A part of the thesis deals with rock falls and basic mechanical characteristics of a rock mass. Further on, the thesis describes selected classification systems, specifically RQD, RSR, RMR, SMR, Q-system, Q-slope, GSI, RSR-PR and QTS. These systems were then used for evaluation of stability of rock slopes on three geologically different locations of the Bohemian Massif. information from measurement in field and processing of measured data was used for assessing for possible use of each classification system.
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Record of mechanical processes during emplacement of shallow-level postcaldera intrusions: an example from Cínovec granite, Bohemian Massif
Vitouš, Petr ; Tomek, Filip (advisor) ; Trubač, Jakub (referee)
Collapse calderas are volcanic depressions created by emptying of underlying magma chamber during volcanic eruption and following fall of upper layers. After this the event is often succeeded by resurgence and magma chamber is filled with new magma, which may lead to creation of dike complexes and laccoliths. Inner structure of these resurgent magmatic bodies is defined by many processes like injection of magma, flow and deformation by local and regional stress fields. During crystallization, magma is still vulnerable to deformation, crystals may react to these deformations and orient themselves to it, and the inner structure may become overprinted. So, the creation of magmatic structures happens during final stages of emplacement and records only the last increment of deformation of magma. For studying the existence of inner structures even from macroscopically isotropic rocks, which may show the characteristics of mechanisms of creation of these rocks, I chose the anisotropy of magnetic susceptibility technique (AMS). This work is focused on the Cínovec granite in the Altenberg- Teplice caldera, Krušné hory mountains on the border between Czechia and Germany. Apart from the studied Cínovec granite this caldera is penetrated by series of other granitic bodies. The result of my study is for interpretation...
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Formation of mafic granulites as a result of metamorphic and metasomatic processes at the contact of felsic and ultramafic lithologies (Dunkelsteiner Wald granulite massif, Bohemian Massif)
Zelinková, Tereza ; Racek, Martin (advisor) ; Hasalová, Pavlína (referee)
English Abstract The Dunkelsteiner Wald granulite massif in Lower Austria belongs to the Gföhl unit of the Moldanubian zone of the Bohemian Massif. Predominant rocks are felsic granulites which in some places contain garnet pyroxenites and peridotites. There are positions of mafic and intermediate granulites on their intersection. Primary mineral association of mafic granulites is garnet, clinopyroxene rich on Jd and Ca-Tschermack component and kyanite. These rocks probably represent Ca-richer variant of pyroxenites. Contemporary mineral association is make by garnet, clinopyroxene, plagioclase and orthopyroxene. Accessory there is amphibole, spinel, rutile and Ilmenite in the rocks. Sapphire inclusion in garnet cores close to kyanite inclusions has been observed in several cases. Decompression of these rocks creates specific symplectite textures in mafic granulites characterized by plagioclase inclusions. These inclusions are partly or fully surrounded by garnet porphyroblasts on their edges and coarse grain symplectics of plagioclase and pyroxene in matrix. A possible explanation of emergence of this specific texture in rocks on intersection with felsic granulite is an infiltration of melt from felsic lithology. Proof can be the enrichment of K component on edges of plagioclase grains. On the other hand,...
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Three-dimensional ambient noise tomography of the Bohemian Massif
Valentová, Ľubica ; Gallovič, František (advisor) ; Burjánek, Jan (referee) ; Kristek, Jozef (referee)
We have performed 3D ambient noise tomography of the Bohemian Massif. We invert adopted inter-station dispersion curves of both Love and Rayleigh waves in periods 4-20 s, which were extracted from ambient noise cross-correlations, using a two-step approach. In the first step, the inter-station dispersion curves are localized for each period into the so-called dispersion maps. To account for finite-frequency effects, gradient method employing Fréchet kernels is used. Assuming membrane wave approximation of the surface wave propagation at each period, the kernels were calculated using the adjoint method. To reduce the effect of data noise, the kernels were regularized by Gaussian smoothing. The proper level of regularization is assessed on synthetic tests. In the second step, the phase-velocity dispersion maps are inverted into a 3D S-wave velocity model using the Bayesian approach. The posterior probability density function describing the solution is sampled by more than one million models obtained by Monte-Carlo approach (parallel tempering). The calculated variance of the model shows that the well resolved part corresponds to the upper crust (i.e., upper 20 km). The mean velocity model contains mainly large scale structures that show good correlation with the main geologic domains of the Bohemian...
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Palaeoclimatic study of the Cenomanian flora of Bohemian Massif
Čepičková, Jana ; Kvaček, Zlatko (advisor) ; Sakala, Jakub (referee)
The aim of this research is to analyse selected plant species from the specific Cenomanian deposits of the Bohemian Cretaceous Basin and their subsequent observation for determining climatic conditions in the Cenomanian age. Fossil plants that will serve to show signs come from two localities, specifically Prague, Slivenec and Prague, Malá Chuchle and are stored in the National Museum in the depository in Horní Počernice. For a more complete view of the Cenomanian in the Bohemian Cretaceous Basin are used the descriptions of the locations Prague, Hloubětín and Vyšehořovice. The default method for detecting the paleoclimatic signal is the CLAMP (Climate Leaf Analysis Multivariate Program) analysis, which sets out the approximate climatic conditions that dominated in the Cenomanian. Key words: palaeoclimatology, Cenomanian flora, Bohemian Massif
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Determination of the age of secondary uranium minerals using 230Th/234U in selected localities of the Bohemian massif
Roll, Michal ; Goliáš, Viktor (advisor) ; Mizera, Jiří (referee)
This thesis is focused on prominent uranium deposits in Czech Republic and their secondary uranium mineralization. Main goal of this thesis is to analyze collected minerals and to determine their ages. Next step is to prove or disprove hypothesis that this secondary uranium minerals are products of Quaternary glacier weathering. As a suitable analytical method, an alpha spectrometry was used and the age was calculated by 230 Th/234 U ratio. Firstly, chosen methodology was verified with admixture of reference material PU1 (Přibram uraninite) in secular equilibrium and internal standard, both with known activity. Analyzed spectra confirmed that some of the samples lay on the very edge of datability, especially in case of PL1 and GF1, both samples are very young, so they easily could be products of anthropogenic activity (changed environment due to mining works). On the other hand, in case of sample GF3, the age was successfully determined, although it is also quite young phase. In case of samples ME3, ME4 and ME6 was used threshold dating method, because they were considered to be too old for age calculation. The rest of the samples chosen for age determination was analyzed without further complications. Based on the age and geological setting, samples GF3 (3 725 ± 845 years), JE1 (10 655 ± 1 795...
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The Origin of Compositional and Textural Zoning of Shallow-Level Granitoid Plutons
Trubač, Jakub ; Janoušek, Vojtěch (advisor) ; Broska, Igor (referee) ; Siebel, Wolfgang (referee)
The principal goal of this Ph.D. Thesis is to contribute to the research on formation of compo- sitional and textural zoning in shallow-level plutons. Processes responsible for emplacement of individual plutons/pulses and the origin of compositional zoning in are addressed in a great detail, from the pluton-scale down to the micro-scale. The main emphasis in the more focused part of this text is on a combination of various quanti- tative data sets from two well-selected plutons (the Říčany Pluton in the Central Bohemian Plu- tonic Complex and the Melechov Pluton in the Moldanubian Batholith). These detailed studies are supported by further research on the Štěnovice, Čistá and Ševětín plutons. In this way we cover the evolution of Variscan magmatism in the heart of Bohemian Massif in its entirety, from Late Devonian till Permian. The thesis is based on combining field and structural studies (including the anisotropy of mag- netic susceptibility, AMS), textural analysis, petrological, geochronological and geochemical methods with geophysical investigations. Mathematical approaches have been designed and applied to the interpretation of geochemical data, with potential applications to other igneous systems. I strongly believe that only such comprehensive studies on well-selected case examples have a...
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Variability of chemical composition of apatites from alkaline rocks of the Bohemian Massif
Mészárosová, Noemi ; Skála, Roman (advisor) ; Filippi, Michal (referee)
III Summary This thesis is focused on crystal chemistry and crystal structure of apatites from alkaline rock of the Bohemian Massif. Fifteen samples of volcanic rocks, mostly of the Cenozoic age was selected for the study. Sample No. 5 is of the Silurian age. Sample No. 15 originates from volcanic rock of the Cenozoic age from the Slovak Western Carpathians. This sample was chosen for this study due to its substantially different chemical composition. The contents of major and minor elements in apatites were measured on an electron microprobe, the contents of some minor and trace elements were determined by laser ablation inductively coupled plasma mass spectrometry. Selected samples were investigated by cathodoluminescence (CL) spectrometry. Crystal structure of studied apatites was characterized by X-ray diffraction and Raman spectroscopy. It was found that dominant anion at position X is fluorine. The OH content calculated on the basis of the fully occupied position X is significant in some samples. The amount of Cl is generally low. The exception is the sample No. 15 where Cl reached up to 0.6 apfu (Z = 2). Studied apatites contain many substitutions but they are generally of minor extent. Strontium, iron and REE at position M belong to the most common and most important substituents for calcium in...
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