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Tectonic and metamorphic evolution of the Tokar-Barka Terrain (East-African Orogeny)
Hořenínová, Marie ; Verner, Kryštof (advisor) ; Peřestý, Vít (referee)
in English This bachelor's thesis summarizes the tectonic and metamorphic evolution of the Tokar-Barka Unit in the southern part of the Arabian-Nubian Shield. The compilation includes an information of regional division, lithological pattern, age, deformation structures and record of metamorphic evolution, mainly in the context of East African orogenic processes. The main episodes of geodynamic evolution are briefly discussed in a regional context. Key words: East-African Orogeny, Arabian-Nubian Shield, Tokar-Barka Unit, Deformation, Tectonics, Metamorphic evolution
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Structural evaluation of angular unconformities
Pešata, Ondřej ; Peřestý, Vít (advisor) ; Rez, Jiří (referee)
Spatial relations between rock layers which are not stratigraphically, structurally, sedimentologically or paleontologically coherent are called unconformities. To be exact we refer to a plane localised between two unconformably deposited layers. This plane is also supposed to serve as a marker of processes which lead to a complete change of an environment on a regional scale at least. This thesis is devoted to a brief history of the recognition of unconformities, formation of unconformities by erosion agents and finally their classification and importance in structural geology. Particularly it focuses on angular unconformities for their easier identification in the field and at the same time for having fundamental tectonic significance. Angular unconformities represent important types of surfaces, because they are used to identify orogenic events, especially when polyphase deformation history is recorded by older strata (deposited beneath unconformity) as opposed to a simpler record of younger ones. Erosion is essentially related to unconformable surfaces as it creates new depositional areas (reliefs) for younger rock layers. For the purposes in this thesis we divide unconformities to "true" and "false". The "true" angular unconformities correspond to an orogenic event, while the "false" angular...
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Age of metamorphism and geodynamic evolution of Vepor Unit in the Central Western Carpathians
Rajmonová, Eliška ; Jeřábek, Petr (advisor) ; Peřestý, Vít (referee)
Western Carpathians are characteristic for their complicated geological structure and uncertain tectogenesis. To understand the context of geological structure and evolution it is important to date the rock units and compare the results with geochemical analysis. The dating can bring results of the age of rocks or of their specific minerals. And because the minerals do not grow at the same time in the rocks, it is possible to date the exact event, which is connected with the growth of an exact mineral and with that connected structure. With respect to the results of dating and observing it is possible to create a model of geological evolution in the locality and support the idea of an exact geological period. The subject of this research is the Vepor Unit in the Central Western Carpathians. The dated rocks (orthogneiss and quartzite) contain garnets that are a product of metamorphosis and for that reason, the garnets are younger than the protolith. This research aims to find the age of the garnets and the age of the associated metamorphosis using the Lu-Hf method. Based on some older articles the age of metamorphosis is assumed to be on the boundary of the Lower and Upper Cretaceous. The research is also focused on the chemical composition of garnets and the macroscopical structure of the rocks...
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Structural evolution of infra- and superstructure boundary in orogens
Peřestý, Vít ; Lexa, Ondrej (advisor) ; Franěk, Jan (referee)
ENGLISH ABSTRACT This work focuses on structural and deformational aspects of the crust development during orogeny, based on historical suprastructure/infrastructure concept. The uppermost suprastructure is dominated by steep fabrics, which evolved in a brittle regime within early stages of orogeny, and which sustain almost unchanged for the whole period of orogenic evolution. On the other hand, the infrastructure is located in the lower crust, where ductile processes dominate. Because the ductility is a thermally activated process, sufficiently long time is needed to heat the lower crust, and therefore the infrastructure is younger than suprastructure. Gently to shallowly dipping structures develop as a consequence of ductile flow. The aim of this study is to describe processes on the suprastructure/infrastructure boundary. Position of this boundary is closely related to brittle/ductile transition, and so that a brief introduction to rheology is included. Rheological boundaries are often places of high strain and high displacement gradients, which must be somehow accomodated. One possibility is to lose communication between adjacent levels and create a detachment plane, which is commonly supposed in the conventional thrust tectonics model. The other possibility is, that layers are at least partially...
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The role of deformation partitioning on the tectonic evolution of the superstructure-infrastructure transition in the Teplá-Barrandian domain
Peřestý, Vít ; Lexa, Ondrej (advisor) ; Konopásek, Jiří (referee) ; Grasemann, Bernhard (referee)
Upper part of the orogenic crust (superstructure) significantly differs from the lower part of the crust (infrastructure) by structural and metamorphic record. This fundamental observation is explained by interruption of the mutual evolution due to mechanical decoupling of the hot and ductile infrastructure from the cold and brittle superstructure at certain stages of the orogenic evolution. The superstructure-infrastructure transition zone is a rheologically predisposed domain of sharp deformation and metamorphic gradients with polyphase structural record. Understanding of the deformation partitioning in such a rheologically complex setting is a key aspect in linking of the individual deformation stages between upper and lower crust. The transition zone between unmetamorphosed early-Variscan superstructure (Teplá-Barrandian Domain) and late Variscan high- grade infrastructure (Saxothuringian Domain) crops out at the western margin of the Teplá- Barrandian Domain in the Bohemian Massif. This area is a continuous mid- to lower-crustal section with early-Variscan structural and metamorphic record, which is superposed onto pre-Variscan episode. This thesis aims to decipher individual deformation events, to evaluate their manifes- tations at different crustal levels and to bring new and unifying...
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The role of deformation partitioning on the tectonic evolution of the superstructure-infrastructure transition in the Teplá-Barrandian domain
Peřestý, Vít ; Lexa, Ondrej (advisor) ; Konopásek, Jiří (referee) ; Grasemann, Bernhard (referee)
Upper part of the orogenic crust (superstructure) significantly differs from the lower part of the crust (infrastructure) by structural and metamorphic record. This fundamental observation is explained by interruption of the mutual evolution due to mechanical decoupling of the hot and ductile infrastructure from the cold and brittle superstructure at certain stages of the orogenic evolution. The superstructure-infrastructure transition zone is a rheologically predisposed domain of sharp deformation and metamorphic gradients with polyphase structural record. Understanding of the deformation partitioning in such a rheologically complex setting is a key aspect in linking of the individual deformation stages between upper and lower crust. The transition zone between unmetamorphosed early-Variscan superstructure (Teplá-Barrandian Domain) and late Variscan high- grade infrastructure (Saxothuringian Domain) crops out at the western margin of the Teplá- Barrandian Domain in the Bohemian Massif. This area is a continuous mid- to lower-crustal section with early-Variscan structural and metamorphic record, which is superposed onto pre-Variscan episode. This thesis aims to decipher individual deformation events, to evaluate their manifes- tations at different crustal levels and to bring new and unifying...
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Assessing the location of a location for placement of deep geological repository of RAW and RAW in terms of long-term safety - Temelín - South site (ETE-J)
Havlová, V. ; Pertoldová, J. ; Hroch, T. ; Štědrá, V. ; Jankovec, J. ; Říha, J. ; Červinka, R. ; Baier, J. ; Černý, M. ; Dudková, I. ; Dušek, K. ; Franěk, J. ; Gondolli, J. ; Gvoždík, L. ; Hokr, M. ; Holeček, J. ; Jelínek, J. ; Kachlíková, R. ; Kaláb, Zdeněk ; Klajmon, M. ; Kolomá, K. ; Královcová, J. ; Kučera, R. ; Kryštofová, E. ; Maryška, J. ; Milický, M. ; Ondra, P. ; Pacherová, P. ; Peřestý, V. ; Polák, M. ; Řihošek, J. ; Rukavičková, L. ; Steinová, J. ; Svoboda, J. ; Šír, P. ; Uhlík, J. ; Vašíček, R. ; Vavro, Martin ; Vopálka, D. ; Zeman, O.
This report summarises outline of a report for evaluation of the sites‘ suitability for the emplacement of a deep geological repository on the basis of the archive information and the geological survey conducted from surface.\nSites are evaluated according to the following criterion categories\n1. Geological characteristics of the site\n2. Hydrogeologic characteristics of the site\n3. Transport characteristics of the the site\n4. Site stability\n5. Factors, increasing probability of human intrusion into the site\n6. Acceptability of enginnered barrier properties under site conditions
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Polyphase structural evolution of superstructure and infrastructure in orogenic zones
Peřestý, Vít ; Lexa, Ondrej (advisor) ; Pitra, Pavel (referee)
Polyphase structural evolution of superstructure and infrastructure in orogenic zones Proterozoic basement rocks of the Teplá-Barrandian Unit (TBU) are affected by two main tectono-metamorphic events. The central and SW part of the TBU is a well-preserved relict of Cadomian episode. On the other hand, the western margin of the TBU shows superposition of polyphase early-varicsan deformation and metamorphism onto the pre- variscan fabric. The Střela river profile in the northern part of Teplá Crystalline Complex (TCC) exposes a continuous crustal section through western margin of the TBU from the low-grade phyllites (near biotite izograd) in the east to the high-grade rocks of kyanite zone at the contact with high-pressure Mariánské-Lázně Complex (MLC). Three main deformation events were distinguished in the studied area and the cross-section is interpreted as a fossil (devonian) suprastructure-infrastructure transition zone preserved in the carboniferous TBU superstructure. The oldest pre-variscan D1 phase produced flat-lying metamorphic foliation showing normal metamorphic zonation from the very low-grade in the upper part to at least garnet zone in the structurally lower part. Large scale upright folding of prevariscan foliation S1 occurred during early-variscan D2 event. Tight F2 folds were...
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Structural evolution of infra- and superstructure boundary in orogens
Peřestý, Vít ; Lexa, Ondrej (advisor) ; Franěk, Jan (referee)
ENGLISH ABSTRACT This work focuses on structural and deformational aspects of the crust development during orogeny, based on historical suprastructure/infrastructure concept. The uppermost suprastructure is dominated by steep fabrics, which evolved in a brittle regime within early stages of orogeny, and which sustain almost unchanged for the whole period of orogenic evolution. On the other hand, the infrastructure is located in the lower crust, where ductile processes dominate. Because the ductility is a thermally activated process, sufficiently long time is needed to heat the lower crust, and therefore the infrastructure is younger than suprastructure. Gently to shallowly dipping structures develop as a consequence of ductile flow. The aim of this study is to describe processes on the suprastructure/infrastructure boundary. Position of this boundary is closely related to brittle/ductile transition, and so that a brief introduction to rheology is included. Rheological boundaries are often places of high strain and high displacement gradients, which must be somehow accomodated. One possibility is to lose communication between adjacent levels and create a detachment plane, which is commonly supposed in the conventional thrust tectonics model. The other possibility is, that layers are at least partially...
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