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Fault tectonics of the selected areas of the South Bohemian Moldanubicum
Paulusová, Barbora ; Hartvich, Filip (advisor) ; Stemberk, Jakub (referee)
The master thesis focuses on the identification of the traces of active tectonics and their influence on the current relief. The study area is situated in the South-Bohemian Moldanubicum, the core area of the Bohemian massif. Two partial areas of interest were chosen for the detailed analyses, the Lhenice fault zone and Kaplice furrow, aiming to assess their tectonic activity. The introductory part concisely presents the geological and tectonic development of Moldanubicum, providing essential context, along with a summary of the research methods, suitable for the research of tectonic imprint in the relief. Digital data were utilized to perform various analyses in both areas of interest. Morpholineaments, thalwegs, and faults were measured and geophysical and seismic data were analyzed. Morphometric parameters were also calculated to assess the level of activity. Through analysis of tectonic joints, the influence of tectonics on the relief was thoroughly discussed. Geophysical measurements (using electrical resistivity tomography) confirmed the existence and course of faults. Additionaly, the areas of tectonic influence and active tectonic areas were identified. Notably, active faults were delineated, and possibly unknown faults were identified within the active regions. Finally, the conclusions...
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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...
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Low-temperature evolution of granulites in the Moldanubian Zone of the southern Bohemian Massif
Kořínková, Dagmar ; Svojtka, Martin (advisor) ; Matějka, Dobroslav (referee)
The Variscan orogeny occured during Devonian to Carboniferous convergence between peri- Gondwanan crustal segments and the northern European plate (Baltica). Due to the convergence, Bohemian Massif represents the easternmost and largest exposure in the European Variscan belt. In the southern part of the Bohemian Massif, the Moldanubian Zone consists of several crustal segments with different polyphase tectonometamorphic histories. Moldanubian Zone is considered to represent the Variscan orogenic root, being surrounded by rigid and less metamorphosed blocks to the NW and SE. Structurally highest unit of the Moldanubian Zone is the Gföhl Unit, which is built by heterogeneous assemblage of high-pressure crustal and upper-mantle rocks comprising granulites, peridotites, pyroxenites and eclogites exhumed during Variscan orogeny. The apatite samples studied in my diploma thesis come from different types of granulites from the Blanský les granulite massif (BLGM) located SW of the town of České Budějovice. BLGM is the largest granulite body of the southern Bohemian Massif, is an integral part of the Gföhl Unit. BLGM consists mainly of calc-alkaline high-pressure felsic garnet ± kyanite granulites, which enclose up to several kilometers long lenses of ultrabasic rocks, numerous boudins of mafic...
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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...
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Structural evolution, magnetic fabric and mechanism of exhumation of the Podolsko complex
Burjak, Miroslav ; Žák, Jiří (advisor) ; Franěk, Jan (referee)
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...
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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...
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Petrogenesis and emplacement of post-collisional granitoids of southeastern Moldanubian Batholith
Hájek, Tadeáš ; Verner, Kryštof (advisor) ; Houzar, Stanislav (referee)
The Weinsberg Composite Pluton, located in the southern part of the Moldanubian Batholith is a large intrusive body with complex internal fabrics, petrogenesis and emplacement processes. On the basis of geochemistry and zircon morphology classification the dominating lithology in the northeastern part of the pluton seems to be the second type of the Weinsberg granitoids (WbG II). Based on the integration of the structural, petrological and geochemical data set acquired from the investigated area, the interpretation of geodynamic evolution and emplacement of the eastern part of the Weinsberg Pluton could be proposed. This interpretation invokes: (a) indentation and underthrusting of a continental microplate (Brunia) in the east at around ~340-330 Ma, driving mantle delamination and subsequent heating and anatexis in the metapelitic lower crust as the heterogeneous source for Weinsberg- and Eisgarn-types of granitoids; (b) subsequent growth of a large metamorphic dome along the edge of the Brunia indentor followed by polyphase emplacement of entire eastern part of the Moldanubian Batholith around ~330-325 Ma including the Weinsberg Composite Pluton in the south; (c) increasing role of the N-S shortening and associated NW-SE dextral shearing along localized shear zones which caused the prevailing...
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Fluid inclusion study of pegmatites from Vepice and Vlastějovice
Surmová, Petra ; Zachariáš, Jiří (advisor) ; Dolníček, Zdeněk (referee)
Fluid inclusions of pegmatites from two localities in the Moldanubina Zone were studied in order to constrain PT conditions of their crystallization and establish composition and properties of fluids associated with pegmatite formation. The first locality is Vepice near Tábor, second locality is Vlastějovice near Zruč nad Sázavou. Pegmatit of Vepice consists of irregular pockets in amphibole- biotic granite dark type to a porphyric syenodioritot Čertova břemene. Fluid inclusions have been studied in several cm large quartz crystals of miarolic cavities from the central zone pegmatites pockets within the central zone of the pegmatite pockets. The collected fluids are aqueous- type with a low salt content (usually in the range of 4-6 hm% NaClekv. Pegmatites in Vepice among the complex Y-REE-Nb-Ta-Ti pegmatites. In terms of PT conditions pegmatites belong to the classification of rare element pegmatite or miarolitic's pegmatites. The studied sample of Vlastějovice (skarn's body) represented a transition from quartz-feldspar pegmatite lithium zone to zone with predominance of quartz (quartz core). Only one sample was studied, which originated from the historical collections F. Čech (Čech, 1985). The sample is an exceptional presence of large quantities of the solid phase (up to 4-5 stages). Using Raman...
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