Doctoral theses
In progress since 2023
In progress since 2020
In progress since 2019
Defended in 2023
The most important results from each study case can be summarized as follows. (1) The Kdyně pluton was an apical part of a domal structure in the upper crust and was primarily controlled by magma buoyancy rather than tectonic deformation through rapid (at ca. 524–523 Ma) and multiple emplacement processes (magma wedging and lateral expansion with minor stoping mechanism). The deformation during the pluton emplacement was partitioned into simple shear-dominated zones that delimited pure shear-dominated belts. This rapid heat input into the former accretionary complex of Blovice was perhaps due to slab break-off, indicating the initial stage of extension in the Teplá–Barrandian unit. (2) The Příbram–Jince basin was influenced mainly by synsedimentary faulting (a series of horsts and grabens) and dominated by continental conglomerates, coarse-grained sandstones, and thin tuffaceous layers deposited in alluvial fans, flood plains, and river channels. The tectonic setting evolved from pure shear dominated with the sediment sourced from pre-Cambrian terranes to a pull-apart dextral transtension with its source coming from the local material of Blovice accretionary complex during ca. 511 Ma. This tectonic setting was coeval with the separation of the Avalonian–Cadomian belt from the northern Gondwana margin and the initial opening of the Rheic Ocean. (3) The slab break-off in the Teplá–Barrandian unit was followed by lithospheric thinning that caused emplacement of granitic magma in the Moldanubian zone (Moldanubian orthogneisses) due to basalt underplating in the extended crust. This event was coeval with the Avalonia ribbon terrane’s rift–drift transition and opening of the Rheic Ocean (at ca. 485 Ma).
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Defended in 2015
This Ph.D. thesis shows that preexisting environment and active faulting of volcano–plutonic systems may largely control emplacement of volcanic and plutonic rocks as exemplified by the dynamics of growth and construction of lava domes and subvolcanic magma chambers. Furthermore, as opposed to theoretical models, it has been demonstrated that even very shallow-level small-scale intrusions are able to record subtle tectonic strains still in magmatic state. Although the fabrics in plutons preserve only one short snapshot of the inferred instantaneous strain, detailed analysis of syntectonic plutons characterized by hypersolidus fabrics together with precise radiometric dating could unravel complex deformation histories at regional scale over a long period of time. Finally, it has been proposed that pluton fabrics may be used to decipher kinematics of lithospheric plate convergence or divergence and changes in their past relative motions.
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Defended in 2012
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).
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Master theses
In progress since 2023
Defended in 2023
Analog models have been widely used as a tool to reconstruct and understand the geological process, too great to observe in real-time. Subduction of solid mass seamounts, the significant topographic elevations, was focus of several studies by analogue “sandbox” and numerical modeling of recent years. However, the natural seamounts are commonly surrounded by loose blocks as a part of the Ocean Plate Stratigraphy. This thesis focuses on the topography of the ocean basin, analog modeling of seamount subduction and the effect of the topographic elevations on the deformation of the accretionary prism, during subduction of the various shapes of seamounts. A series of experiments were performed to study these processes and specially, the effect of the loose blocks on the structure of the wedge stratigraphy, particularly, on formation of mélanges.
Defended 2020
Better understanding of pyroclastic density current (PDC) dynamics is one of the key volcanological focuses, as PDCs represent one of the most life-threatening volcanic hazards. PDCs associated with explosive collapse calderas are difficult to observe and examine directly, and thus research of internal architecture of calderas and their PDC deposits is focused on extinct and partly eroded volcano-plutonic systems. Such a case is the Late-Carboniferous Altenberg–Teplice caldera in NW Bohemian Massif, which exposes a large body of ignimbrites (deposits of the PDC) called Teplice rhyolite (an intra-caldera fill). This body is well exposed on the southern flank of the Krušné hory/Erzgebirge Mts., mainly its members: Teichweg, Lugstein-Pramenáč, Vlčí kámen-Medvědí vrch and Přední Cínovec. As these ignimbrites appear macroscopically isotropic, I employed the Anisotropy of magnetic susceptibility (AMS) in order to quantify their internal structure. A total of 1232 specimens from 63 sampling stations were analyzed for the AMS, complemented by susceptibility vs. temperature variations and petrographic observations. Obtained AMS data, carried by a mixture of paramagnetic ferrosilicates and low-Ti titanomagnetite, indicate various processes recorded in ignimbrites. The relatively oldest and moderately welded Teichweg member exhibit subhorizontal oblate magnetic fabrics indicating general westward flow directions corroborated by asymmetry of flow foliated flattened fiamme, whereas the source vents were likely situated around the eastern caldera rim. In contrast, Lugstein-Pramenáč, Vlčí kámen-Medvědí vrch and Přední Cínovec members are characterized by higher degree of anisotropy and triaxial to prolate magnetic fabrics, indicating rheomorphic viscous flow obscuring primary flow fabrics. In addition, I hypothesize magnetic fabrics of some local domains around younger post-caldera intrusions are compatible with caldera resurgence that occurred shortly after deposition of still hot and ductile ignimbrites. In terms of PDC dynamics, the exposed portion of the Teplice rhyolite is complex body recording PDC flow directions, welding, rheomorphism and possible a caldera resurgence.
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Defended in 2016
Diploma thesis deals with geological, petrological and geochemical studies of neovolcanic rocks of the SW part of the Most Basin in the area of Tušimice power plant open pit. There are two lava flows affected by coal mining in northern part of the mine. Petrological and geochemical studies with K-Ar dating relatively recent rocks in mostly weatherworn volcanic rocks showed, that they can be classified as Ti-rich basaltic rocks without olivine (tephrites), which belong to the main volcanic phase in the evolution of the Eger graben. It was evidenced geologicaly and with K-Ar dating, that studied rocks were seperated from underlying beda by hiatus which caused erosion of volcanic rocks as well as crystalline bedrock. Mmajor and trace elements composition of co-magmactic volcanics showed that rock were derived from two slightly different sources of upper mantle. Composition of two samples indicates the formation from low degree of partial melting strongly metasomatic asthenospheric mantle. Chemical features of volcanic rocks show that mantle source was comparamble to recent OIB basalts. Last sample arose from less metasomatized and depth distincted mantle which was affected by higher level of partial melting. Melts from which crystallized both rocks were minimaly affected by asimilation or contamination. Extention of lithosphere in Alp forefield and output of mantle diapir facilitated the output of oligocene magma in the beginning of main volcanic phase of the Eger rift evolution. Increased subsidence enabled deposition of few hundred meters thick sequence of overlying coal-bearing sediments.
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Defended in 2015
Diploma thesis deals with geological, petrological, structural and geochemical studies of the most probably neoproterozoic volcanic and sedimentary rocks of the Pičín belt in the area NW from Dobříš, approximately between the villages Trnová and Chouzavá. Volcanics of Kozí hory area, which are demonstrably included into Davle Formation have beeen used for comparison with the Dobříš area. One of the major part of the work includes geological mapping on scale of 1:10 000, which served as a base for a more detailed petrological, structural and geochemical studies
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Defended in 2013
This thesis concentrates on a detailed field and structural analysis of the Podolsko complex, Moldanubian unit, Bohemian Massif, complemented by a microstructural study and analysis of magnetic susceptibility (AMS). The Podolsko complex occupies the footwall of a major Variscan normal shear zone and is juxtaposed against the southern to southeastern margin of the Central Bohemian Plutonic complex. During the field work, more than 160 outcrops were examined, the AMS samples were taken at 25 stations, and samples for microstructural studies were taken from 12 localities. On the micro-scale, leucocratic migmatites contain abundant garnet grains which may represent relics of an earlier (ultra-)high preassure metamorphic phase. Retrogression is obvious in other samples of biotite migmatites of the Moldanubian Variegated unit. The retrogression is marked by the presence of sillimanite and chlorite. The main tectonometamorphic event in the Podolsko complex is extensive migmatization coeval with formation of pervasive flat-laying fabric. This is corroborated by the AMS study which indicates concordant steep to flat-laying magnetic and mesoscopic foliations striking NNW–SSE. The AMS also shows that the subhorizontal N–S to NNW–SSE trending magnetic lineations in the Podolsko complex correspond to those in the structurally overlying Červená granodiorite. In conclusion, these data suggest a common principal extension direction and strong coupling between upper brittle and middle anatectic crust in the eastern part of Variscan orogen during gravity-driven collapse of the Teplá–Barrandian unit.
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Bachelor theses
In progress since 2023
In progress since 2021
Defended in 2023
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 that the formation, growth, collapse, and eruption of a highly viscous endogenous lava dome occurred directly in the quarry or its immediate vicinity, which could explain the distribution of the distinguished rhyolite facies. These interpretations, therefore, revealed another of the series of eruptive centers of the Křivoklát-Rokycany volcanic complex. The results of the bachelor’s thesis can further be used to accurately define the newly discovered eruption center in Těškov and its surroundings, or other potential centers in the remaining parts of the porphyritic rhyolite.
Defended in 2021
Subduction zones, domains where oceanic lithosphere is subducted into the mantle beneath an overriding plate, are one of the most dynamic tectonic environments. A wide range of the long-lasting subduction-zone processes may be suitably reproduced and studied through analog modeling and thus may be directly observed in laboratory, though at time and length scales that differ fundamentally from nature. The main goals of this Bachelor thesis are first to provide an overview of large-scale architecture of subduction zones, to present an overview of the published analog experimental methods, and then to discuss the main outcomes of analog modeling of subduction zones and accretionary prisms. The thesis also summarizes the main mechanical parameters of materials used in the analog modeling. Furthermore, a set of simple experiments were performed, with the main goal to model formation of basalt-bearing mélanges during subduction of seamounts and volcanic belts that may occur on ocean floor and are commonly incorporated into accretionary wedges as dismembered Ocean Plate Stratigraphy (OPS).
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Defended 2018
Collapse calderas are volcanic depressions created by emptying of underlying magma chamber during volcanic eruption and following fall of upper layers. After this the event is often succeeded by resurgence and magma chamber is filled with new magma, which may lead to creation of dike complexes and laccoliths. Inner structure of these resurgent magmatic bodies is defined by many processes like injection of magma, flow and deformation by local and regional stress fields. During crystallization, magma is still vulnerable to deformation, crystals may react to these deformations and orient themselves to it, and the inner structure may become overprinted. So, the creation of magmatic structures happens during final stages of emplacement and records only the last increment of deformation of magma. For studying the existence of inner structures even from macroscopically isotropic rocks, which may show the characteristics of mechanisms of creation of these rocks, I chose the anisotropy of magnetic susceptibility technique (AMS). This work is focused on the Cínovec granite in the AltenbergTeplice caldera, Krušné hory mountains on the border between Czechia and Germany. Apart from the studied Cínovec granite this caldera is penetrated by series of other granitic bodies. The result of my study is for interpretation of mechanisms of Cínovec granite intrusion, the AMS method is not suitable. It is so because the rock underwent series of post-magmatic processes like greisenization and hydrothermal alteration. These post-magmatic processes caused recrystallization of the original magmatic minerals so that the rock probably does not bear the record of intrusion mechanisms. Apart of the realization, that the greisenization of Cínovec granite interferes even with rocks outside of localities mapped as greisen, the rock is heavily fractured, which makes it impossible to take a good sample of rock for the AMS analysis.
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