|
|
The Late Devonian to early Carboniferous kinematic evolution of the Teplá-Barrandian/Moldanubian boundary
Tomek, Filip ; Žák, Jiří (advisor) ; Babuška, Vladislav (referee)
ENGLISH ABSTRACT The Late Devonian to Early Carboniferous kinematic evolution of the Teplá-Barrandian/Moldanubian boundary The Staré Sedlo complex (SSC) is a relic of meta-igneous arc-related pluton in the southern part of the Sedlčany-Krásná Hora roof pendant, intruded by granitoids of the Central Bohemian Plutonic Complex along the boundary of Teplá-Barrandian (TBU) and Moldanubian units (MU), Bohemian Massif. The SSC mainly comprises deformed orthogneisses of calc-alkaline granodiorite to tonalite protoliths of Late Devonian age (380−365 Ma; Košler et al., 1993) that were commonly mingled with minor basic magmas. Locally preserved subhorizontal intrusive contacts of the orthogneisses against their meta-sedimentary host rock indicate that these magmas intruded as a sill complex. The SSC preserves a rather unusual flat-lying subsolidus foliation (dip <40ř) associated with subhorizontal ~NE-SW-trending mineral lineation. Mesoscopic structures, anisotropy of magnetic susceptibility (AMS), and deformational microstructures indicate prolate shape of the strain ellipsoid with dominant coaxial pure shear regime. The solid state microstructures record cooling of the orthogneiss protolith down to the ambient greenschist facies conditions followed by its static recrystallization due to the intrusion of the younger...
|
|
|
Tectonic evolution of the central part of the Teplá-Barrandian unit
Hajná, Jaroslava ; Žák, Jiří (advisor) ; Schulmann, Karel (referee) ; Nance, Damian (referee)
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). The most important conclusions of the thesis are as follows. (1) The Neoproterozoic (Cadomian) basement of the Teplá-Barrandian unit reveals a complex structure and mostly unclear stratigraphic relations of its components. It was proposed that this unit exposes perhaps the best preserved fragment of an accretionary wedge of the whole Avalonian-Cadomian belt, represented by the newly defined Blovice Complex. In the central part of the TBU, this complex consists of three lithotectonic belts differing in style and intensity of deformation, magnetic fabric, and degree of Cadomian regional metamorphism. In addition, the central...
|
|
|
Emplacement and magnetic fabrics in dikes of syenite porphyries (Western Moldanubian Zone)
Orságová, Lucie ; Verner, Kryštof (advisor) ; Žák, Jiří (referee)
ENGLISH ABSTRACT We present new results of structural and magnetic (AMS) analyses of selected dikes of melasyenite, quartz melasyenite to melagranite porphyries accompanied by lamprophyres (minettes). The studied dike from the locality Nihošovice were dated by U-Pb method on zircons at 338 Ma. The asymmetric structural pattern of the studied dikes gives an excellent evidence for their emplacement and orientation of magmatic flow. The studied dikes were emplaced into: (i) Prevailing parts of the Central Bohemian Plutonic Complex (locality Malčice) and (ii) host high-grade metamorphic rocks of western part of the Moldanubian Zone (locality Nihošovice). Despite of the extensive area of occurrence, compositional variations and age of emplacement of these dikes are relatively narrow. Their geochemical and petrological compositions broadly correspond to ultrapotassic plutonic rocks (durbachites). The dikes are steeply dipping in trend ~NNW-SSE to ~W-E, with range in width between ~20 and ~25 meters. In general, our results show: (i) A relatively low degree of magnetic anisotropy (P= 1.012 - 1.152); (ii) Mostly oblate (planar) fabric, especially in marginal parts of the intrusive bodies (T= -0.091 - 0.941); (iii) Evidence for subhorizontal magmatic flow trajectory defined for a newtonian magma with typical...
|
|
| |
|
|
Usage of basic elements of Greco-Roman wrestling for teaching physical culture on basic school
Žák, Jiří ; Štěpánek, Jan (advisor) ; Vejsada, Jindřich (referee)
Title work: Usage of hasíc elements of Greco-Roman wrestlíng for teaching physícal culture on hasíc school Purposes work: The maín goal of the presented díploma work ís to compile the elements of the Greco-Roman wrestling style to a form of a methodícal guíde for the ínstructors, hased on the research propaganda, and create the propsal ofa thematic plan ofthe tuitíons suitahle for the primary schools. Method: methodologícal studies evaluation postures questioning questionnaíre analysis Results: Setting up the resistance exercises to the schools education schedules. Improvement of the gym classes and hringíng out of the stereotypes, especially ofhall games. Possitive evaluatíon ofthe students and ímprovement oftheir physical form. Increasing interest of the students in the comhat sports as in consequences ofthe contemporary fears. Key words: wrestle Greco-Roman, rules, hasíc elements, metodology ofthe education, comhat sports, material comparison, decision makíng
|
|
|
Mechanisms of differentiation and emplacement of peraluminic granite magma: Říčany pluton, Bohemian Massif
Trubač, Jakub ; Žák, Jiří (advisor) ; Závada, Prokop (referee)
English abstrakt This thesis is focused on emplacement mechanisms of granitic magma into upper continental crust. The studied area is the Říčany pluton due to its unusual and asymmetric shape. Therefore, it represents a suitable intrusion for interpretation different models referring to emplacement of granitic magma. Common model for ascent of magma is incremental diking in present. The Říčany pluton of the Central Bohemian Plutonic Complex is a post-tectonic elliptical shallow-level intrusion emplaced into low-grade Neoproterozoic and Lowe Carboniferous times (~337 Ma). It comprises of outer, more fractionated, strongly porphyritic granite and inner, less evolved, weakly porphyritic granite. Mesoscopic foliation represents an onion-skin pattern and corresponds well to the magnetic (AMS) foliations. Magnetic lineation has a gentle dip (0-20ř) and closely parallels with the pluton contact in its outer part whereas the lineation dips steeply (60-70ř) with a variable trend in the pluton interior. Author interprets these fabrics as a result of a helical flow, which is a faster subvertical flow in the low-viscosity pluton centre being accompanied by a subhorizontal flow in the outer, higher-viscosity (phenocryst-rich) margin. The proposed scenario of the helical magma flow can provide a viable mechanism for the...
|
|
|
Forearc deformation and strain partitioning during growth of a continental magmatic arc: the northwestern margin of the Central Bohemian Plutonic Complex, Bohemian Massif
Dragoun, František ; Žák, Jiří (advisor) ; Ulrich, Stanislav (referee)
This doctoral thesis is focused on analysis of tectonic deformations associated with the Late Devonian subduction followed by the Early Carboniferous continental collision of the Saxothuringian and overriding upper-crustal Teplá-Barrandian units, which led to the growth of a large magmatic arc (the ~354-337 Ma Central Bohemian Plutonic Complex) in the central part of the Bohemian Massif. Far-field tectonic forces resulting from the collision produced ~WNW-ESE to ~NW-SE regional shortening across the forearc upper crust above the subduction zone; the shortening was accommodated by predominantly top-to-the-ESE tectonic transport along the southeastern flank of the Teplá-Barrandian unit. Approaching the magmatic arc margin, the regional structural pattern changes and exhibits significant acrossand along-strike variations interpreted as a result of strain partitioning, where the Saxothuringian/Teplá-Barrandian convergence interacted in different ways with the intruding magma pulses. Around the voluminous, northeasterly ~354 Ma Sázava pluton the principal shortening was at high angle to the forearc-facing intrusive contact and the host rocks were significantly thermally softened. The regional top-to-the-ESE tectonic transport converted here into arc-parallel ductile flow within the structural aureole...
|
|
| |
|
|
Subduction-driven shortening and differential exhumation in a Cadomian accretionary wedge: The Teplá?Barrandian unit, Bohemian Massif
Hajná, Jaroslava ; Žák, Jiří (advisor) ; Franěk, Jan (referee)
2. English abstract This doctoral thesis is focused on analysis of tectonic deformations a geodynamic evolution of Neoproterozoic and Lower Paleozoic rocks of the Teplá−Barrandian Unit along the northwestern margin of the Prague basin (central Bohemian Massif). Using a wide range of modern methods, correlation of finite deformation patterns in different units allowed separation of structures formed during Cadomian and Variscan orogeny and interpretation of tectonic processes and tectonic history of the Cadomian orogenic belt during late Neoproterozoic. The research found direct evidence for and enabled new interpretations of Cadomian tectonic processes in the Bohemian Massif, including a succesion of deformation phases, quantification of finite deformation gradients and mechanisms. The different data sets were finally combined into an overall geotectonic model of Cadomian orogeny and its Variscan tectonothermal overprint in the Bohemian Massif, as well as the data were used for correlation with other Avalonian−Cadomian terranes. 5
|
|
| |
guest ::
