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Geomorphological evolution of the Hřebeny Ridge in Brdy
Soukupová, Lenka ; Balatka, Břetislav (referee) ; Kalvoda, Jan (advisor)
4 ABSTRACT The main aims of presented study about the geomorphology of the Hřebeny Ridge in Brdy Mts. are 1/ the documentation of landform patterns and 2/ the description of main stages of the relief evolution. In opening chapters of the paper, the natural envi- ronments of the Hřebeny Ridge and Brdy Mts. as a whole are characterized. In the fol- lowing chapter, a reflection of the geological structure in present-day landforms is de- scribed. Landform analysis of the studied region related to climate-morphogenetic pro- cesses is presented and detailed geomorphological map (1:10 000) is enclosed. Final part of the study is concerned with main stages of the landform evolution of the Hřebeny Ridge. Field observation and its geomorphological interpretation are compared with earlier regional studies. The presented paper demonstrates that landforms of the Hřebeny Ridge in Brdy Mts. are determined by the geological structure, e.g. by the geomorphological resistance of rocks. Present-day landforms of the Hřebeny Ridge evolved in the Quaternary. Im- portant processes of the landform evolution of the region are connected with the origin of deep river valleys. The landform patterns of the ridge part and its slopes are essential- ly influenced by the Pleistocene cryogenic weathering of rocks as well as very intensive...
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Climate operation at the turn of the 18th and 19th century in memories of F.J. Vavák
Málková, Štěpánka ; Soukupová, Jana (advisor) ; Vokoun, Martin (referee)
This thesis focuses on documentary sources, mainly chronicles and memoirs of historical and contemporary terms and their use for meteorological purposes. The climate in the end 18th and the beginning 19th centuries, influenced mainly conclude the Little Ice Age, which was characterized by a strong cooling and temperature fluctuations. Memories of F. J. Vavák, neighbour and mayor of Milčice were investigated from the years 1770 to 1816 and evaluated records on weather and other factors affecting the climate and the evolution of agricultural crops between the years 1770-1816. This work also describes the historical context and inclusion in the context of historical and climatological during arising from the memories of František J. Vavák and impact on the life of the time population.
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Studium rovnováhy mezi klesajícími kapkami železa a roztavenými silikáty v magmatických oceánech
Ulvrová, Martina ; Velímský, Jakub (advisor) ; Šrámek, Ondřej (referee)
During the Earth's accretion process deep magma oceans were episodically formed. Differentiation of iron took place within the melted zone and small droplets of iron were sinking to the base of the magma ocean due to the density contrast. In the present work we study the process of equilibration between dispersed metal droplets and surrounding silicates that proceeds by the advection transport and diffusion at the rim. We allow for steady state ow of a spherical liquid blob falling in a host liquid and establish the numerical code in axisymmetric spherical coordinates computing the chemical evolution of such heterogeneous system. We focus on determining the time scales of equilibration for which we propose an analytical model based on the boundary layer analysis. The obtained characteristic times are especially for low silicate viscosities very short that supports the idea that the drops attained equilibrium while sinking.
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Evolutionary strategy in biomineralization of mollusc shells: Micromechanical properties of shells and their relationship with the environment
Hrabánková, Iva ; Frýda, Jiří (advisor) ; Marika , Marika (referee)
This thesis deals with the micromechanical properties (microhardness and elastic modulus) of selected molluscan shell microstructures and their relationship to crystallographic textures and environment. Results of the study suggest that extremely high hydrostatic pressure has a relatively weak influence on the mechanical properties of calcitic as well as aragonitic shell layers. No statistically significant difference was found in microhardness and elastic modulus of nacre between bivalvian species living in marine and freshwater environments. On the other hand, the study reveals a statistically significant positive correlation between the micromechanical properties and thickness of aragonitic platelets forming the nacre. Unexpected result is a negative correlation of the degree of ordering of aragonitic platelets with both elastic modulus as well as microhardness. Thus the degree of ordering explains about 80% of the variability of these micromechanical properties. Statistically significant but weaker correlation was also found between micromechanical properties and textural type of bivalvian nacre. The nacre with uniaxial texture is harder and more elastic than the nacre with quasimonocrystallic texture. The data suggests that higher hardness and elasticity corresponds to a primitive state of nacre and that during the subsequent evolution values of these micromechanical properties were decreasing. This trend contradicts with generally accepted hypothesis of increassing predation pressure in the marine ecosystem during the Paleozoic and Mesozoic.
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The structure of native pine stands in eastern Bohemia.
Marková, Kateřina ; Vacek, Stanislav (advisor) ; Miroslav, Miroslav (referee)
Abstract
This work deals with the issue of the structure of pine stands also in Europe with a focus on natural forests in the Czech Republic and, in particular, in Eastern Bohemia. The work shows the characteristics of the area of interest Třebechovické the Board and in the NPR Adršpach-Teplice Rocks, and in particular the site and stand conditions. The goal is to acquire knowledge about the structure and evolution of the natural pines in Eastern Bohemia, focusing, in particular, n poor acidified in the bory Třebechovické boards and relict pine forests in the NPR Adršpach-Teplice Rocks. For measurements in the field system was used by the Field-Map, the biometric characteristics are measured stand (the stem thickness, height of trees, the height of the deployment the Green Crown, Crown projection, the location of the trees in the shade), the position of the dead wood and from them created situational maps of the areas. The results obtained will serve primarily as the basis for the creation of the nature of the middle management in pine stands in a similar site and stand conditions.
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Rendering Surface Detail with Advanced Mapping Techniques
Stehlík, Lukáš ; Pelikán, Josef (referee) ; Ambrož, David (advisor)
The thesis deals with algorithms of computer graphics which exploit advanced techniques of textures mapping with the aim of improving the projection of details of wrinkled surfaces. The evolution and architecture of modern graphic cards are described. There is the description of basic characteristics of the Cg language for graphical accelerators too. Algorithms for simulation of wrinkled surfaces such as normal (bump) mapping and parallax mapping are described in detail including the explanation of basic terms and principles. Extra focus is laid on the method named displacement mapping and its application on modern graphical cards. The thesis describes possible improvements of the above mentioned methods with a view to problem of implementation of displacement mapping method. Part of the work is a program that visualizes methods including improvements. There is a discussion on results obtained from testing the program on different graphical cards. All the methods and their improvements are compared with respect to both the projection quality and the speed of processing.
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Hydrodynamic and thermal mode ling of reactive flow in the surroundings of intrusions
Jandová, Tereza ; Dolejš, David (advisor) ; Bruthans, Jiří (referee)
English Summary Intrusion of magma into the Earth's crust is associated with significant thermal perturbations, release of aqeuous fluids and formation of hydrothermal system. In order to better understand the feedback relationships between fluid flow, thermal evolution and permeability variations, we have modeled conductive and advective cooling of a shallow- crustal pluton using the SHEMAT software. Our model represents a two-dimensional cross section through the lithosphere with homogeneous material properties, whebery the heat and mass conservation equations are solved by finite difference method. We first calculate the stable lithospheric geotherm by emplying constant basal thermal flow of 40 mW m-2 and a constant surface temperature. Subsequently, we consider a rectangular magmatic intrusion emplaced at 5-10 km depth, which forms a contact aureole by conductive cooling. With time, a mushroom-like shape of the contact aureole is predicted. Inclusion of aqueous fluid flow into the model causes only a small alteration of thermal evolution mainly because the permeability is low and the fluid mass is negligible due to very low density under hydrothermal conditions. In addition to thermal effects, we have explored variations in hydraulic head in order to address the ensuing effects on the flow velocity. The...
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Tectonic evolution of the Mariánské Lázně Complex and of surrounding units
Hafoudh, Shumran ; Konopásek, Jiří (advisor) ; Franěk, Jan (referee)
Tectonic evolution of the western margin of the Bohemian Massif is the result of southeastward Devonian subduction of the Saxothuringian Ocean followed by collision of the Saxothuringian continental crust with the easterly lying Teplá-Barrandian Domain during early Carboniferous (e.g. Franke 2000). Northwestern flank of the Teplá Barrandian Domain is represented by mafic and ultramafic rocks of the Mariánské Lázně Complex usually considered as an ophiolite complex documenting the closure of the Saxothuringian Ocean (e.g. Kastl &Tonika, 1984, Beard et al., 1994). Mariánské Lázně Complex is in the NW thrust over medium-grade metabasites and metasediments of the Kladská Unit with suggested Saxothuringian affinity (Kachlík, 1993), and in the SE it is overthrust by medium- to highgrade metasediments of the Teplá Complex (Cháb & Žáček, 1994). Geochronological data show that the northwestern flank of the Teplá-Barrandian Domain was exhumed already during Upper Devonian (Dallmeyer & Urban, 1998) and suggest apparent lack of deformation and metamorphism associated with Carboniferous collision. Our study has concentrated on structural record along the profile from the Kladská Unit to the Teplá Complex in order to separate structures produced during Devonian subduction and exhumation from those developed during...
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The Late Devonian to early Carboniferous kinematic evolution of the Teplá-Barrandian/Moldanubian boundary
Tomek, Filip ; Žák, Jiří (advisor) ; Babuška, Vladislav (referee)
ENGLISH ABSTRACT The Late Devonian to Early Carboniferous kinematic evolution of the Teplá-Barrandian/Moldanubian boundary The Staré Sedlo complex (SSC) is a relic of meta-igneous arc-related pluton in the southern part of the Sedlčany-Krásná Hora roof pendant, intruded by granitoids of the Central Bohemian Plutonic Complex along the boundary of Teplá-Barrandian (TBU) and Moldanubian units (MU), Bohemian Massif. The SSC mainly comprises deformed orthogneisses of calc-alkaline granodiorite to tonalite protoliths of Late Devonian age (380−365 Ma; Košler et al., 1993) that were commonly mingled with minor basic magmas. Locally preserved subhorizontal intrusive contacts of the orthogneisses against their meta-sedimentary host rock indicate that these magmas intruded as a sill complex. The SSC preserves a rather unusual flat-lying subsolidus foliation (dip <40ř) associated with subhorizontal ~NE-SW-trending mineral lineation. Mesoscopic structures, anisotropy of magnetic susceptibility (AMS), and deformational microstructures indicate prolate shape of the strain ellipsoid with dominant coaxial pure shear regime. The solid state microstructures record cooling of the orthogneiss protolith down to the ambient greenschist facies conditions followed by its static recrystallization due to the intrusion of the younger...
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Variscan and pre-Variscan tectonometamorphic processes in external zones of the Bohemian Massif-examples from the Krkonoše-Jizera Massif and the Letovice Complex
Žáčková, Eliška ; Konopásek, Jiří (advisor) ; Kachlík, Václav (referee) ; Kryza, Ryszard (referee)
Tectonometamorphic processes in external zones of the Bohemian Massif during Lower Palaeozoic were studied in this work. The studied areas cover the northeastern part of the Saxothuringian Domain (Krkonoše-Jizera Massif) and the Letovice Complex located between the western margin of the Moravian Zone and the eastern edge of the Moldanubian Domain. Evolution of both these units was influenced by Early Palaeozoic rifting and Devonian- Carboniferous Variscan orogenesis. In the Saxothuringian Domain, Variscan processes were connected with subduction of the Saxothuringian ocean below the easterly exposed core of the Bohemian Massif and resulted in the development of high-pressure low-temperature metamorphism. Thermodynamic modelling of metamorphic evolution in metapelites from the Krkonoše-Jizera Massif suggests that these rocks record peak pressure conditions of ≥18-19 kbar at 460-520řC followed by isothermal decompression to pressures of 10.5-13.5 kbar and final decompression to <8.5 kbar and <480řC. The calculated peak P-T conditions indicate a high-pressure/low-temperature apparent thermal gradient of ~ 7-7.5 řC km-1 . Laser ablation inductively coupled plasma mass spectrometry (ICP-MS) isotopic dating and electron microprobe chemical dating of monazite give ages of 330 ±10 Ma and 328 ±6 Ma,...
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