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Comprehensive study of the sandstone rock forms deterioration (Case study: Pravčická brána Arch, Bohemian Switzerland National Park)
Vařilová, Zuzana ; Přikryl, Richard (advisor) ; Vilímek, Vít (referee) ; Mikuláš, Radek (referee)
This PhD thesis contains the results of comprehensive research into the Pravčická brána Arch and surrounding sandstone massifs with focus on gaining more knowledge about natural dynamics and evolution of this rock formation, its current level of stability and the weathering processes it displays. Non-destructive methods were used for this comprehensive study; these ranged from detailed field documentation to monitoring temperature regime of the rock and included application of a geophysical survey and control monitoring of the course of arch body deformation. Laboratory testing was carried out for strength parameters and salt efflorescences together with weathered sandstones were analysed for chemical compounds. Main operating factors were monitored simultaneously, which particularly involved changes in external temperature, degree of sunlight and chemical composition of rainfall. Conventional as well as entirely new assessment procedures were used in synthesis and interpretation of the data collected, including knowledge of nonlinear dynamics of complex systems. The survey was designed to fully respect the protective conditions of the site, to make follow-up activities possible in future and to monitor any possible negative changes in the rock massif. The main results incorporate description of...
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Elemental and isotopic study of differentiated meteorites and implications for the origin and evolution of their parent bodies
Halodová, Patricie ; Košler, Jan (advisor) ; Řanda, Zdeněk (referee) ; Kanický, Viktor (referee)
ELEMENTAL AND ISOTOPIC STUDY OF DIFFERENTIATED METEORITES AND IMPLICATIONS FOR THE ORIGIN AND EVOLUTION OF THEIR PARENT BODIES Iron meteorites are differentiated meteorites composed largely of Fe-Ni alloys. The metallic phase of many iron meteorites shows a texture called the Widmanstätten pattern, which develops as a two-phase intergrowth of kamacite (α-bcc, ferrite) and taenite (γ-fcc, austenite), and forms by nucleation and growth of kamacite from taenite during slow cooling of the parent body. Selected iron meteorites - octahedrites of different structural and chemical groups (Canyon Diablo, Toluca, Bohumilitz, Horh Uul, Alt Biela, Nelson County, Gibeon and Joe Wright Mountain) were studied with intention to evaluate the scale and extent of Fe isotopic heterogeneities in iron meteorites and to find the possible link between the isotopic variations and thermal histories of the respective meteorite parent bodies. The Fe isotopic compositions of kamacite and taenite in the studied meteorites, obtained by three independent analytical techniques with different spatial resolution capabilities (laser ablation and solution MC ICP-MS and SIMS) show significant variations of up to ~4.5‰ in δ56 Fe. The taenite is isotopically heavier compared to kamacite in all studied meteorites. There is no correlation...
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Geophysical and remote sensing methodologies applied to the analysis of regolith and geology in Burkina Faso, West Africa
Metelka, Václav
The oldest parts of continents, so-called cratons, are the focus of worldwide research not only because they represent primary constraints for our understanding of the early evolution of the Earth, but also because of their significant mineral potential. This work contributes to the understanding of the geological and geomorphological evolution of the West African Craton, by an integrated analysis of airborne geophysical and satellite remote sensing data constrained by field structural, lithological, geophysical, and geomorphological observations acquired around Houndé, Boromo and Banfora greenstone belts and associated granitoid domains in western Burkina Faso. The results of this integration suggest that the granitoid domains of western Burkina Faso are formed by numerous small- to medium-sized plutons, and the magnetic data provided a better definition of the actual pluton shapes. Airborne gamma ray spectrometry data aided in the mapping process in areas with less regolith cover. Three deformation events (D1-D3) can be distinguished in western Burkina Faso. A megacrystic tholeiitic basalt unit allowed us to establish stratigraphic correlations between the two belts and propose a crustal scale anticline (D1). The D1 penetrative structures, resulting from an E-W to WNW-oriented compression are...
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Tectonic evolution of the central part of the Teplá-Barrandian unit
Hajná, Jaroslava ; Žák, Jiří (advisor) ; Schulmann, Karel (referee) ; Nance, Damian (referee)
The principal goal of the thesis is to examine the tectonic evolution of the Teplá- Barrandian unit (TBU) of the central Bohemian Massif from Cadomian subduction and active margin processes, through Cambro-Ordovician extension to Variscan terrane collisions. The thesis is based on extensive field research, detailed structural mapping, and structural analysis, combined with other analytical methods such as the anisotropy of magnetic susceptibility (AMS) coupled with an analysis of magnetic mineralogy, analysis of deformational microstructures, and U, Th and Pb isotope analyses carried out by laser ablation - inductively coupled plasma-mass spectrometry (LA-ICP-MS). The most important conclusions of the thesis are as follows. (1) The Neoproterozoic (Cadomian) basement of the Teplá-Barrandian unit reveals a complex structure and mostly unclear stratigraphic relations of its components. It was proposed that this unit exposes perhaps the best preserved fragment of an accretionary wedge of the whole Avalonian-Cadomian belt, represented by the newly defined Blovice Complex. In the central part of the TBU, this complex consists of three lithotectonic belts differing in style and intensity of deformation, magnetic fabric, and degree of Cadomian regional metamorphism. In addition, the central...
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Record of Cambro-Ordovician Extension in the Teplá Crystalline Unit
Jašarová, Petra ; Racek, Martin (advisor) ; Kusbach, Vladimír (referee)
In my thesis I would like to summarize informations about SW part of the Teplá- Barrandian Unit. Particularly interesting situation is in the Teplá Crystalline Complex and Mariánské-Lázně Complex during Cambro-Ordovician rifting. At the beginning I will remind some basic information about Bohemian Massif (evolution and distribution). The next part of the thesis is dedicated to the west part of the Teplá-Barrandian Unit in the context of sedimentary record in the eastern part of the Unit. In two other captures is described Teplá Crystalline and Domažlice Crystalline Complex with emphasis on the plutons, which help us to reveal evolution of this area. In the third part of the thesis I will characterize Mariánské- Lázně Complex (lithology, dating and evolution). This complex was interpreted as a dismembered Cambro-Ordovician metaophiolite complex affected by Variscan subduction. But the latest studies show that the HP rocks protoliths are late Cadomian age, thus the eclogites probably originated during exhumation of this area. According to new results the Mariánské-Lázně Complex represent a metamorfic core complex and the Teplá Crystalline Complex is the detached roof of it. The corronitic metagabbros on the border between Mariánské-Lázně and Teplá Crystaline complex are generally interpreted to be...
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Origin of karst conduits and caves in Jizera Formation in Turnov.
Slavík, Martin ; Bruthans, Jiří (advisor) ; Schweigstillová, Jana (referee)
Aim of this study is to characterize the processes responsible for evolution of open conduits and caves in Jizera Formation near Turnov, in particular to distinguish if the main factor acting in enlargements of conduits is dissolution and the conduit system can be called karst, or if the process is caused by erosion of weakly cemented sandstone without contribution of dissolution. An important part of the study is to introduce the concept of self-organization. Based on results from accelerated simulation of dissolution of twenty rock samples, SEM analysis and drilling resistance, I have proved that rocks in Jizera Formation near Turnov dissolve in an acidic environment and their strength characteristics does not enable direct erosion by flowing water. Samples from localities of "Bartošova pec", "Slepé údolí Podhorčí", "Rozsedlinové ponory pod Drábovnou", "Šetřilovsko", "U Kačeny" and "Semikraska" dissolve, but behavior of samples from "Sudoměř - rybník" and "Sudoměř - Skalský potok" is in an acidic environment very similar to samples from Teplice Formation "Skalní pískovcový výchoz u Podhorčí" and "Valdštejn".
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Subduction-driven shortening and differential exhumation in a Cadomian accretionary wedge: The Teplá?Barrandian unit, Bohemian Massif
Hajná, Jaroslava ; Žák, Jiří (advisor) ; Franěk, Jan (referee)
2. English abstract This doctoral thesis is focused on analysis of tectonic deformations a geodynamic evolution of Neoproterozoic and Lower Paleozoic rocks of the Teplá−Barrandian Unit along the northwestern margin of the Prague basin (central Bohemian Massif). Using a wide range of modern methods, correlation of finite deformation patterns in different units allowed separation of structures formed during Cadomian and Variscan orogeny and interpretation of tectonic processes and tectonic history of the Cadomian orogenic belt during late Neoproterozoic. The research found direct evidence for and enabled new interpretations of Cadomian tectonic processes in the Bohemian Massif, including a succesion of deformation phases, quantification of finite deformation gradients and mechanisms. The different data sets were finally combined into an overall geotectonic model of Cadomian orogeny and its Variscan tectonothermal overprint in the Bohemian Massif, as well as the data were used for correlation with other Avalonian−Cadomian terranes. 5
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Response of selected rivers of the Bohemian Massif to lithological and structural conditions
Flašar, Jan ; Nývlt, Daniel (advisor) ; Kalvoda, Jan (referee)
Three groups of streams were selected in the area of the Bohemian Massif: the Berounka river with its source streams; the Vltava river with its tributaries the Malše and the Lužnice; the Labe river with its tributaries the Cidlina, the Bystřice and the Javorka. The lithological and tectonical influences to several parameters of the streams were studied. These parameters include: stream gradient, orientation of the stream and sinuosity of the stream. Data were obtained from digital elevation models, aerial photographs, topographical and geological maps. The longitudinal profiles of the streams (in the combination with geological cross-sections), the SL indexes and the gradient/sinuosity graphs were created on the basis of the obtained data. These tools were used for evaluation of the influence of lithology and the tectonics to the streams. The evolution of the streams and the stream-groups was evaluated and compared as well. A strong influence of lithology on the stream gradient was found on most of the analysed streams. The tectonic situation, on the contrary, had strong influence on the orientation of the streams, especially in the resistant rocks. Also, there were selected areas, where was a higher probability of quaternary vertical movements influencing the streams (mountainous areas of the Novohradské...
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Concentrator photovoltaic systems
Straškraba, Vojtěch ; Solčanský, Marek (referee) ; Vaněk, Jiří (advisor)
The subject of this bachelor´s thesis is to introduce concentrator photovoltaic systems, history of their foundation, evolution and application, principles of function and description of technology including its construction, optics, special photovoltaic cells and their cooling. The practical part of thesis describes the experimental concentrator photovoltaic system build in cooperation with Solartec s.r.o. company. The system is used to test hypotheses and study the behavior during its operation. The aim is to measure concentration ratio, temperature and electrical characteristics and to compare advantages of active and passive cooling of photovoltaic cells.
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Origin and evolution of silcretes
Kohoutová, Iveta ; Zachariáš, Jiří (advisor) ; Adamovič, Jiří (referee)
Summary: Silcretes are rocks with high content of SiO2 (usually more than 90 wt. %) formed by mobilization of SiO2 during weathering processes. Silcretes formed near the Earth's surface by soil weathering in warm and humid climate are termed as pedogenic silcretes. Another type of silcrete is groundwater silcrete, whose origin is usually associated with the groundwater table and depths of 5-50 m below the surface and arid to semi-arid climate. The third type of silcretes is associated with evaporites. Its genesis is complicated; as well it is difficult to date this silicification. There are four types of silcrete textures: GS-, F-, M-, C- textures; the most common is the F-texture. In the Czech Republic silcretes are more known under the term "sluňáky" or "quartzite". Indeed, in every country where they occur, have their own specific name. Silcretes are essentially composed of SiO2, minor constituents represent heavy minerals and/or feldspar. Cement is mostly α-quartz, chalcedony and opal. Average thickness of silcretes is 1-3 m, rarely 5 meters. Main source of SiO2 is chemical weathering of silicate minerals or quartz dust grains carried by wind and deposited on natural barriers, like blades of grass. There are two models of silcrete formation: lateral and vertical transport model SiO2. Sedimentary...
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