National Repository of Grey Literature 15 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Volumetric and electrostatic properties of water and their application to aqueous thermodynamics and mineral solubility at high temperatures and pressures
Hanková, Barbora ; Dolejš, David (advisor) ; Zachariáš, Jiří (referee)
Hydrothermal fluids are important mass and heat transfer agents in the Earth's crust and mantle. Aside from their transport role, the aqueous fluids act as reactants or products in rock environment during diverse processes ranging from partial melting, magmatic and metamorphic devolatilization. This study evaluates the effect of equations of state and thermodynamic data for aqueous species on prediction of mineral solubility in aqueous fluids at high temperatures and pressures employing the Helgeson-Kirkham-Flowers model (HKF). These calculations require: (i) volumetric properties of water; (ii) dielectric properties of water; (iii) aqueous species thermodynamic properties. A comparison of ten equations of state against the IAPWS scientific standard reveals that volumetric properties of water up to 1200 řC and 50 kbar are predicted within 5 %, except at low pressure (below 2 kbar), temperatures higher than 1000 řC, and the liquid-vapor equilibrium curve, particularly in the proximity of the critical point of water. The deviations of volumetric and electrostatic properties of water propagate into the mineral solubility calculations. For quartz and corundum these deviations lead to discrepancy in mineral solubility of up to half an order of magnitude for molal concentrations. These discrepancies...
Thermokinetic model and quantitative description of magmatic textures
Špillar, Václav ; Dolejš, David (advisor) ; Marsh, Bruce D. (referee) ; Higgins, Michael D. (referee)
Variability of magmatic textures records a wide array of physicochemical and mechanical processes that have operated in a magma chamber during its crystallization. Here I investigate how the final textural record can quantitatively be used to decipher the magma crystallization history and internal dynamics of magma chambers. The thesis is based on a formulation of numerical models of texture formation under the activity of various crystallization processes. Numerical results are then compared to the new quantitative textural datasets derived from four distinct magmatic systems in the Bohemian Massif: (i) Fichtelgebirge-Smrčiny granite batholith; (ii) Krkonoše-Jizera plutonic complex; (iii) Kdyně mafic intrusion; (iv) České středohoří volcanic complex. Combination of the field textural studies with their interpretation via numerical crystallization models provides new implications regarding magmatic crystallization and internal dynamics of magma chamber. The most important results of this Ph.D. thesis are as follows: (i) a new method has been developed that allows the rates of nucleation and growth of crystals to be derived from quantitative textural data. The method requires using the crystallinity evolution in time as an independent constraint in order to provide unique solution. In case of the...
Small-scale volcanoes on Mars: image analysis, numerical modeling and comparison with terrestrial analogs
Brož, Petr ; Dolejš, David (advisor) ; Rothery, David (referee) ; Baratoux, David (referee)
Small-scale volcanoes represent diverse group of landforms which vary in morphology, morphometry, and mechanisms of their formation. They are the most common volcanic form on Earth, and their existence and basic characteristics were also predicted for Mars. Availability of high-resolution image data now allows to search, identify and interpret such small volcanic features on the martian surface. This thesis extends our knowledge about the small-scale volcanoes with the following objectives: (a) to document the existence of martian analogues to some of the terrestrial volcanoes, in particular scoria cones, tuff cones, tuff rings and lava domes; (b) to establish their morphological and morphometrical parameters; and (c) to examine the effect of environmental factors, which differ on Earth and Mars, on the mechanisms of formation of the scoria cones. Interpretation of remote sensing images and digital elevation models reveals that scoria cones, tuff rings and cones, and lava domes exist on different parts of the martian surface and, in some cases, far away from previously well-known volcanic provinces. Scoria cones have been identified in the volcanic field Ulysses Colles situated within the Tharsis volcanic province; tuff cones and tuff rings have been found in the Nephenthes/Amenthes region at the...
Volcanic-hosted massive sulfide deposits: structure, origin and examples from the Iberian Pyrite Belt
Krátký, Ondřej ; Dolejš, David (advisor) ; Zachariáš, Jiří (referee)
English abstract The volcanic-hosted massive sulfide deposits (VHMS) represent one of the key deposit types in the modern world. Due to their polymetallic composition (Zn, Pb, Cu, Ag, Au and Sn in some cases) they are important source of the base metals as well as the precious metals. They have been forming through the Earth's history and are actively forming even now on a modern sea- floor through emanations of hot metal-bearing fluids. Extensive study of the volcanic-hosted massive sulfide deposit began in 1960s after discovery of active seafloor vents on the bottom of the Red Sea (e.g. Miller et al., 1966) in form of black smokers. They represent channels and are results of emanation of the hydrothermal fluids into the water column and actual evidence of the hydrothermal processes. Hydrothermal fluids were enriched in various elements, including base and precious metals. Certain elements (specifically metals) were leached from the host rock (volcanic and sedimentary) by the percolating seawater. This seawater was heated and modified into hydrothermal fluid by a heat from a magmatic intrusion, which represents the driving force of the whole hydrothermal system. This intrusion can be of variable composition - from basic to felsic. Sometimes fluids that are produced by this intrusion are also enriched in...
Textural analysis of granites from the Western Krušné hory/Erzgebirge pluton: implications for crystallization kinetics and crystal-melt interactions
Ditterová, Hana ; Dolejš, David (advisor) ; Závada, Prokop (referee)
Texture of igneous rocks, which includes size, shape and spatial distribution of grains, represents the final record of kinetic and mechanical processes operating during ascent and final emplacement of a magma. However, traditional geochemical approaches cannot assess and verify the physical processes of magma solidification, in particular, crystal nucleation and growth, textural coarsening, or mechanical crystal-melt interactions. In this work, I apply stereological methods to quantitatively characterize the textures and to interpret the crystallization history of granitic rocks in the Western Krušné hory/Erzgebirge and Vogtland. The Western Krušné hory/Erzgebirge granites consist of three suites: biotite granites (Kirchberg), muscovite-biotite microgranites (Walfischkopf), and topaz-zinnwaldite alkali- feldspar granites (Eibenstock), which consist of eight intrusive units and two aplite dyke sets. The entire granite sequence exhibits an extreme and nearly continuous differentiation range, but in detail the evolutionary trends of each suite are independent, and individual intrusive units are also clearly compositionally separated. The granites consist of 29-43 vol.% quartz, 20-30 vol. % plagioclase, 22-31 vol. % K-feldspar, 2-9 vol. % biotite, <2 vol. % muscovite, and minor topaz and apatite. All...
Mineral assemblages, alteration reactions and transport model of the greisen formation in the Horní Blatná granite pluton, Krušné hory Mts.
Heřmanská, Matylda ; Dolejš, David (advisor) ; Štemprok, Miroslav (referee)
English abstract Hydrothermal systems related to highly evolved granitic magmas host diverse mineralization styles and provide an important source of economic metals. This master thesis concentrates on description and interpretation of geological structure, petrographic and textural variability, alteration zoning and calculation of time-integrated fluid fluxes recorded in highly evolved granites and tin-mineralized greisens of the Horní Blatná massif in the Western Krušné hory pluton. The massif is a composite intrusion, which consists of a large number of intrusive units emplaced during two stages. The first stage is represented by sparsely porphyritic fine-grained low-lithian annite granites that can be correlated with marginal granites (G2) of the Fichtelgebirge (Smrčiny) batholith or with intermediate granites (Walfischkopf type) of the Western Krušné hory (Erzgebirge) pluton. Intrusive batches of the second stage progressively evolve from medium- to coarse-grained serial high-lithian annite and zinnwaldite granites with topaz and rare tourmaline towards aphyric fine-grained zinnwaldite (or trilithionite) granites. This suite corresponds to the EIB2 and EIB3 facies of the younger intrusive complex in the Western Krušné hory (Erzgebirge) pluton and it can be compared to the G3 Waldstein and G4 units in...
Geochemistry and origin of skarns of the Bohemian Massif
Bubal, Jan ; Dolejš, David (advisor) ; Houzar, Stanislav (referee)
Calcic-iron skarns are one of the characteristic part of the regional metamorphic complexes of the Bohemian Massif. Their mineral assemblages, structures and significant enrichment of Ca, Al and Fe were previously interpreted to be primary (exhalation sediment) or secondary (metasomatic carbonates). In this project, which consists of three sub-studies will focus on the geochemical composition of skarn as the main arguments for the discussion of their origin. Malešov deposit belongs to the typical calcic-iron skarns whose mineral assemblages are not very different from similar skarns associations in the Bohemian massif. It consists of lenticular body that is stored in gneiss and migmatites of the Kutná Hora crystalline complex. On the deposit prevails garnet-pyroxen skarn, less abundantly represented garnet and magnetite skarns and skarns replacement by amphibole or epidote. Fine-grained garnet skarns are formed by isotropic dark red garnet (Adr78-88Prp0-0.3), while in massive garnet rocks garnet grains form the core (Adr13-38Prp2.5), which envelop newly formed garnet (Adr28-66Prp1.6). In association with them is often pyroxene (Hd60-90) which can be replaced by hastingsite amphibole composition. Other minerals present are magnetite, Fe-epidote, calcite and albite. Magnetite and pyroxene skarns are...
Differentiation and crystallization of evolved granitic melts, the Říčany pluton, central Bohemian Massif
Jandová, Tereza ; Dolejš, David (advisor) ; René, Miloš (referee)
Evolved silicic rocks display a variety of igneous textures, which can provide important information on crystallization kinetics and rheology in natural magma chambers. Individual kinetic effects such as diffusion rate, nucleation rate, growth rate and post-solidification modifications are likely to be reflected in the modal and textural appearance of the resulting rock. This work focuses on characterization and interpretation of solidification textures in a 600 m wide and 5 km long body of highly evolved, boron-rich aplites and pegmatites at the southern endocontact of the Říčany granite pluton (Central Bohemian Plutonic Complex). This rock suite is associated with biotite Říčany granite, hosting microgranite and aplite dyke swarm, and it is built up by massive tourmaline aplites, layered aplites with tourmaline-rich or locally garnet-rich bands, pegmatite pockets, pegmatite layers with unidirectional solidification textures (comb layers), megacryst zones (analogous to stockscheider), and late pegmatite dykes discordant to layering. Textural as well as modal variations are usually sharp and observable megascopically as well as on the microscale. All aplites and pegmatites usually contain similar proportions of quartz, albite-rich plagioclase, K-feldspar, various proportions of tourmaline (up to...

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