National Repository of Grey Literature 60 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Genesis of the eruptive center of rhyolite ignimbrites, the Křivoklát-Rokycany volcanic complex
Ptáček, Jakub ; Tomek, Filip (advisor) ; Verner, Kryštof (referee)
English abstract This bachelor's thesis focuses on the tectonic and volcanological characteristics of the Křivoklát-Rokycany volcanic complex in the Teplá-Barrandian unit. The literature research part emphasizes the broader geological context, where I describe the Neoproterozoic, Cambrian, and lower Ordovician geotectonic development of the Teplá-Barrandian unit within the Avalonian-Cadomian orogenic belt. In the Křivoklát-Rokycany volcanic complex, I focus in detail on the relatively youngest part, which consists of the entire spectrum of facies of rhyolite composition and includes coherent lavas, tuffs, ignimbrites, and dike equivalents. The field research of the practical part of the bachelor's thesis took place in a satellite body of porphyritic rhyolite in the Těškov quarry, about 10 km northeast of Rokycany. The aim of the detailed geological mapping of the investigated quarry was the petrographic description of four distinct rhyolite facies, mapping of their spatial distribution, and possible determination of the eruptive center. Other research methods included analyzes of in-situ magnetic susceptibility and size distribution of rhyolite breccia clasts. The result of the work is a three- dimensional model of the quarry with detailed distribution of rhyolite facies. From the obtained data, I assume...
Elastic anisotropy of eclogites and peridotites from the Bohemian Massif
Pohořalá, Anna ; Staněk, Martin (advisor) ; Machek, Matěj (referee)
This bachelor thesis describes the structure of the lithosphere and the factors influencing the velocity of P-wave propagation and their anisotropy in rocks. Fundamental aspects of seismic and laboratory methods for the study of elastic properties of rocks are described with particular emphasis on the method of ultrasonic irradiation of spherical samples under high confining stresses. The results of measurements by this method are presented on 18 samples of eclogites and peridotites from the Bohemian Massif. The rock set is separated according to modal composition, compared and then evaluated using graphs showing P-wave velocity, anisotropy and confining stress relationships. Furthermore, the relationship between anisotropy, P-wave velocity of propagation, density and grain size is shown using a correlation matrix. For the sets of studied rocks, the presence of kelyphites, symplectites, and serpentinites decreases the P-wave velocity, and anisotropy decreases with increasing amounts of serpentinites. Eclogites having high seismic velocities have low anisotropy. Keywords: elastic anisotropy, eclogites, serpentinized peridotites, Bohemian Massif
Late Cenozoic response of the selected fluvial systems of the Bohemian Massif to tectonics.
Flašar, Jan
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...
Crustal Structure of the Bohemian Massif Based on Seismic Refraction Data
Hrubcová, Pavla ; Vavryčuk, Václav (advisor) ; Plomerová, Jaroslava (referee) ; Švancara, Jan (referee)
The deep structure of the Bohemian Massif, the largest stable outcrop of the Variscan rocks in central Europe, was studied using the data of the international seismic refraction and wide- angle reflection experiments CELEBRATION 2000, ALP 2002 and SUDETES 2003. The data were interpreted by seismic tomographic inversion and by 2-D trial-and-error forward modelling of the P and S waves. Above, additional constraints on the crustal structure were imposed by reflectivity or gravity modelling, and by receiver function interpretation. Knowledge of the crustal velocity structure in the Bohemian Massif was complemented by its azimuthal variation. Though consolidated, the Bohemian Massif can be subdivided into several tectonic units separated by faults, shear zones, or thrusts reflecting varying influence of the crust forming processes. The resultant velocity models determined different types of the crust-mantle transition reflecting variable crustal thickness and delimiting contacts of these tectonic units at depth.
Fabrics and geodynamic evolution of orthogneisses in the Moldanubian Zone
Kryl, Jakub ; Verner, Kryštof (advisor) ; Venera, Zdeněk (referee)
Fabrics and geodynamic evolution of Moldanubian orthogneisses English abstract The aim of this paper is a structural analysis of selected mostly Cambro-Ordovician orthogneisses cropping out in a part of high-grade rocks of western Moldanubian Zone. These rocks have been affected by HT-MP/LP metamorphism and the polyphase deformation during the Variscan orogeny. In the blaník orthogneisses, (Qtz + Kfs + Plg + Bt ± Ms ± Sill ± Ky) an early deformation banding dips steeply to SSE to ESE. These fabrics were overprinted by NW to N gently dipping foliation with well developed stretching lineations plunging to W. Rare kinematic indicators (e. g. fold and pressure shadows asymmetry) reveal a strong subvertical contraction and stretching in the ~N-S direction. Based on the microstructural analysis this contractional event was connected with the activity of "Grain Boundary Migration Recrystallization" (GBM). Ductile shear zones dipping to E, locally ESE or ENE were identified. Bechyně orthogneisses (Qtz + Kfs + Plg + Bt ± Ms) is a N-S elongated body with the presence of regional pervasive metamorphic foliation dipping homogenously under low angles from SSW to WNW . These foliations bear well developed mineral or stretching lineation of quartz, biotite and feldspar aggregates plunging to ~SW. In the blaník orthogneiss...
Geodynamic evolution and post-collisional magmatic activity in the Arabian-Nubian Shield (East African Orogeny) and southwestern Moldanubian Zone (Central European Variscides)
Megerssa, Leta Alemayehu ; Verner, Kryštof (advisor) ; Závada, Prokop (referee) ; Johnson, Kenneth (referee)
The Variscan orogenic belt along the exhumed root domain, known as the Moldanubian Zone as well as the Arabian-Nubian Shield (ANS) in the East African Orogeny (EAO) of Ethiopia, are considered as typical areas for studying late-orogenic (post-collisional) processes and magmatism. Based on a wider range of field and analytical methods: field structural mapping, anisotropy of magnetic susceptibility (AMS) analysis, thermobarometric calculation and P-T evolution, conventional U/Pb dating, a reconstruction of geodynamic evolution and magmatism in the southwestern part of Moldanubian Zone (Bohemian Massif) and Tokar-Barka Terrain (southern part of Arabian-Nubian Shield is undertaken. The Variscan case portrays the peculiar overprint by the Late Orogenic tectonothermal event which is absent in the case of the Arabian-Nubian Shield (ANS) hence offering a compelling contrast to investigate the possible underlying mechanism involved for the different processes in the post-orogenic phase. In the southern ANS a post-collisional intrusive Chewo pluton composed of monzodiorite and quartz monzonite marks the late tectonic overprint which intruded into a low-grade Neoproterozoic juvenile crustal Tokar-Barka terrane. Thermobarometric estimations indicate its emplacement to be c. 10-13 Km depth, idealized from AMS...
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.
Geodynamic evolution and emplacement of Eisgarn - type granitoids (Moldanubian Batholith)
Paclíková, Jana ; Verner, Kryštof (advisor) ; Franěk, Jan (referee)
English abstract This diploma thesis deals mainly with identification of magmatic (respectively magnetic) fabrics, geodynamical aspects of emplacement and geochronology of the Eisgarn granitoids. For the analysis Klenov and Mrákotín pluton were chosen, which is placed in the eastern part of the Moldanubian Batholith. This thesis contains petrological and mezoscopic structural analysis of the host metamorphic rocks of the Moldanubian Unit and it includes calculation of P-T conditions of the main mineral assemblage. This is followed by petrological, geochemical and mezoscopic structural analysis of the Klenov and Mrákotín pluton and analysis of the anisotropy of magnetic susceptibility, geochronology of the Klenov pluton, gravimetry analysis and determination of the orientation of density interfaces in different depths. Granitoids of the Klenov and Mrákotín pluton are characterized as S-type granitoids, whose protolith were probably metasedimentary rocks. From the analysis it is also evident that the Klenov pluton records lower degree of magma fractionation than the Mrákotín pluton. The emplacement and crystallization of both studied magmatic bodies took place in cooperation with a development of regional metamorphic fabrics, which originate between 329 and 327 Ma. During this period a rapid exhumation of...
Fabrics of the Weinsberg granitoids on example of the Prášily pluton (Moldanubický plutonický komplex)
Pour, Ondřej ; Verner, Kryštof (advisor) ; Racek, Martin (referee)
This bachelor thesis is concerned with the brief introduction to the structures and fabrics in granitoid plutons. In the next part of this work are sumarized results of structural analyses of Weinsberg-type granite intrusion (Prášily pluton) located in the SW part of high-grade rocks of the Moldanubian Zone. This research proceeded based on a combination of field structural data and results of AMS (Anisotropy of magnetic susceptibility) method. The internal fabrics and structures of the Prášily pluton reflect emplacement mechanisms, kinematic history and evolution of the regional strain field during Variscan orogeny at around 330 Ma. The examined area provides crucial constraints for the geodynamic models of geological evolution of deeper parts of the Variscan orogen in the SW part of the Bohemian Massif.

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