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Deformation history and decomposition of ternary feldspar in the proto-phase of the Blanský les felsic granulite evolution
Jirků, Markéta ; Jeřábek, Petr (advisor) ; Závada, Prokop (referee)
This diploma thesis deals with the oldest recognized deformation microstructure of felsic granulites of Blanský les (southern Bohemian Massif) in order to understand their lower crustal deformation history later altered during exhumation. Moreover, the study is focused on decomposition of ternary feldspars in the proto-phase of evolution of granulite microstructure. Based on the structural and microstructural analyses of the less developed cleavage I. and the more developed cleavage II., it was possible to distinguish between two deformation structures. The S1 is defined by compositional banding of alternating quartz bands with bands rich in plagioclase, garnets and with porphyroclasts of alkaline feldspars. The S1 cleavage is transposed into the S2 cleavage. During intense reworking of S1 into S2, the quartz bands were decomposed and recrystallized into the ribbons. The feldspar thermometry of the cleavage I. and II. allowed to distinguish the three stages of decomposition of feldspars. A continuous temperature decrease was observed as reflected by the individual microstructures. The quantitative microstructural analysis indicate the shape preferred orientation of the grain boundaries of two-feldspar matrix. The shape preferred orientation of cleavage I. is controlled by the albite rim, however after its...
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Study of microstructure of autoclaved aerated concrete with using of secondary raw materials
Martanová, Jana ; Suchý, Peter (referee) ; Kulísek, Karel (advisor)
Autoclaved aerated concrete is a used building material, especially for its thermal insulating properties. During autoclaving, an aerated concrete microstructure produces crystalline CSH phases, primarily tobermorite. The ingoing substances are calcium oxide and silica. In addition to commonly used raw materials, secondary raw materials rich in silicon dioxide can be used for production. The use of secondary raw materials gives the opportunity for the construction industry to be more environmentally friendly. Another benefit is the reduction of financial costs. The work explores the influence of individual secondary raw materials on the microstructure. High-temperature fly ash, fluid fly ash, cinder, ground glass and zeolite were used The raw materials were mixed with unalloyed lime at a molar ratio of calcium oxide to silicon dioxide of 0.73 and 1.0. Autoclaving capsules were used to synthesize tobermorite under laboratory conditions. Autoclave was performed at 170 °C and 190 °C with hydrothermal durations of 4, 8 and 16 hours. The most important influence on the microstructure was high-temperature fly ash, on the contrary, the greatest influence on the mechanical properties is attributed to the ground glass.
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ASR potential of quartz in experimental mortar bar specimens
Kuchyňová, Markéta ; Kuchařová, Aneta (advisor) ; Vavro, Martin (referee)
The alkali-silica reaction is one of the most damaging chemical reactions taking place in concrete, which can cause fatal damage. ASR originates under following conditions: high moisture (> 80 %), sufficient amount of alkaline ions (Ca2+ , Na+ , K+ ) and use of reactive aggregates (low crystaline or deformed quartz, amorphous SiO2). Reactive aggretates react with high alkaline pore solution and produce hydrofile gels. These gels absorb water and swell. Dilatometric test methods are commonly used to evaluate the reactivity of aggregates. The principle of dilatometric test methods is simple. Mortar or concrete prisms are created in a laboratory, then they are stored in the special environment, which accelerates the inception of ASR. The creation and expansion of alkali-silica gels cause prism's length changes. The major goal of this diploma thesis was to evaluate the alkali-silica reactivity potential of quartz-rich rocks using microscopic (polarizing microscopy, scanning electron microscopy combined with SEM/BSE image analysis) and dilatometric (ASTM C1260, RILEM AAR-4.1) methods. Rocks were assessed as reactive, potentially reactive and non-reactive by the ASTM C1260 method. The reactivity of aggregates was connected with the amount of cryptocrystaline matrix, grain size, shape of grain boundaries,...
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Chemistry of hydrothermal quartz from the Mokrsko-West gold deposit determined by the LA-ICP-MS method
Štrba, Martin ; Zachariáš, Jiří (advisor) ; Trubač, Jakub (referee)
The Mokrsko-West deposit, situated about 20 km south from Prague, is one of the most important gold deposits in the Bohemian Massif. We can find hydrothermal quartz veins in two types of host rocks: tonalite in the Central Bohemian Plutonic Complex (CBPC) and amphibolite in the Jílové Belt (JB). A several generations of the quartz veins with different mineralization were found in the deposit. This study has several objectives. At first, it determines and compares the chemistry of quartz samples from different generations of hydrothermal veins. In addition, this work describes the distribution of the most important trace elements. Lastly, the work compares the potential differences in the chemistry of samples from the different host rocks (CBPC and JB). With the use of the LA-ICP-MS, 16 quartz samples from the Mokrsko-West deposit were analysed. Finally, 101 analyses were realized. From the analysed trace elements, the most important were Li, Mg, Al, Ca, Fe, Cu, Zn, As, Sb and Pb. Aluminium affects the concentration of the most of analysed trace elements. Positive correlation between Al and the other metals was also found. The samples with high Al content also showed high concentrations of other metals (Fe, Cu, Zn, Pb) and As. Samples with lower Al content showed lower concentration of other metal...
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Quartz microchemistry as metallogenetic indicator
Pacák, Karel ; Zachariáš, Jiří (advisor) ; Trubač, Jakub (referee)
Region surrounding the Central Bohemian Plutonic Complex represents one of the most important gold bearing zones in the Czech Republic. Several types of gold deposits dominated by hydrothermal quartz gangue were explored here and distinguished: the Intrusion related gold deposits ("Petráčkova hora" and "Mokrsko") and the orogenic gold deposits ("Jílové u Prahy" and "Kasejovice" ). Deposits "Libčice u Nového Knína" and "Roudný u Vlašimi" are partially similar to the orogenic gold type, but are different from other orogenic type deposits in the region. All together 38 samples from these five deposits were analyzed with laser ablation technique (LA- ICP-MS) to produce 228 measurements. Selected samples were selected to represent both main quartz gangue carrying the Au ore and latter weakly mineralized quartz gangue. Samples representing hydrothermal quartz gangue with no direct relation to Au-ore deposits were also collected in order to compare chemical composition of both quartz types originating from the same area. Main concern of this work was in-situ analysis of chemical composition of different generations of quartz gangue and statistical comparison of differences within individual deposits as well as comparing the examined deposits themselves. Total 65 isotopes were measured, trace element...
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Characteristics of polyphase deformation in quartz microstructure: an example from the Krkonoše-jizera Unit
Očenášková, Eva ; Jeřábek, Petr (advisor) ; Závada, Prokop (referee)
Quartzite samples taken in the east part of Krkonoše-Jizera Massif belong to metasedimentary cover of paraautochtonous unit. Rocks underwent a polyphase deformation which established a strong shape preffered orientation (SPO) of quartz grains. In folded quartz veins, deformation overprint mechanisms and microstructure, CPO and SPO relations were studied. For determination of crystal preffered orientations (CPO) the method of computer integrated polarization microscopy (CIP) was used. Microstructural analysis was focused on grain sizes, aspect ratios, long axis orientations and their relation to the deformation overprint grade. Results implies that dominant mechanism of quartz grain recrystallization is grain boundary migration. Folds were created by simple shear in microscale. The deformation overprint grade is strongest in the top of the fold hinge, where grains achieve highest aspect ratios and sizes. In the lower parts of the fold hinge the original CPO is preserved in small grains and SPO has similar orientation to original CPO. During folding CPO and SPO rotated with shear direction in dependance on deformation overprint grade.
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The Effect of Thermal Exposure of the Porosity and Mineralogy of Dense Silica Bricks.
Janek, Ondřej ; Kotouček, Miroslav (referee) ; Nevřivová, Lenka (advisor)
Silica bricks is a refractory building material which contains at least 93 % of silicon dioxide in polymorphic forms, mostly -tridymite, -cristobalite and unreacted -quartz. In glass industry is used for building crowns of glass tanks and in coke industry is used for building coke oven batteries. The advantage is the high refractoriness under load, high resistance to acidic melts. The disadvantage is the low resistance to changes in temperature below 600 °C. The thesis deals with the influence of repeated firing on the silica bricks and to its porous structure and mineralogical composition.
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Study of interactions of organic matter and its components via molecular dynamics
BARVÍKOVÁ, Hana
Humic acids and humates are principal components of humic substances major organic constituents of soil, peat, coal and water around the world. I was involved in research into molecular dynamics simulations of interactions of quartz surfaces with aqueous solutions of ions and small organic molecules representing basic building blocks of larger biomolecules and functional groups of organic matter. We studied interactions of molecules with surfaces for a set of surface charge densities corresponding to the experimentally or environmentally relevant ranges of pH values employing molecular mechanics, molecular dynamics and ab initio techniques. Simulated quartz surfaces covered the range of surface charge densities 0.00, -0.03, -0.06 and -0.12 C-m-2, approximately corresponding to pH values 4.5, 7.5, 9.5 and 11. As model molecules, benzoic acid, phenol, o-salicylic acid and their conjugated bases were chosen. My task was to prepare topologies and parametric models of selected organic matter basic building blocks organic molecules. I focused on studying interactions of these molecules in an aqueous environment with mineral surface quartz. The aim was to process simulation results and analyse conformations of the adsorption complexes and their thermodynamic properties such as interaction energies, free energies and adsorption geometries.
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