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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...
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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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Magnetic fabrics and emplacement of the Eisgarn granitoids (Moldanubian Plutonic Complex)
Paclíková, Jana ; Verner, Kryštof (advisor) ; Buriánek, David (referee)
English abstract We consider our preliminary results of structural and AMS analyses of granitoids of the Mrákotín and Klenov Plutons located in the northeastern part of the Moldanubian Plutonic Complex. Both plutons have a peraluminous, high-K character formed by partial melting of a crustal metasedimentary (metapelite) source at relatively lower temperatures. The Mrákotín pluton (eastern part of the plutonic complex) was emplaced posttectonically at around 327 Ma and records a crucial role of magmatic stoping during magma ascent and emplacement. In contrast, the Klenov pluton (western part of the plutonic complex) was emplaced syntectonically with regional HT-LP tectonometamorphic event (formation of gently to moderately NNE dipping metamorphic schistosity).
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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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GEOMORPHOLOGY OF VELKÝ AND MALÝ BLANÍK
Bártová, Jitka ; Votýpka, Jan (advisor) ; Verner, Kryštof (referee)
Thie thesis consists of three main parts: an introduction, a description of physical conditions in the studied area and a main part which includes results of geomorphologic research and mapping. The area of interest is situated in central Bohemia in preserved area called Blanik. In the region there are two structural hills where the research was done. The names of these hills are Velký and Malý Blaník. Geologic structure of the region is built of Proterozoic - Paleozoic metamorphic rocks of Moldanubicum. Moldanubicum is represented here by muscovite - biotite orthogneiss (called blanicka ) and muscovite - biotite paragneiss. Both hills are created by muscovite - biotite orthogneiss so all the landforms are of its origin. There were classified structural, cryogenic, fluvial and other landforms in this thesis. Special attention was paid to cryogenic forms: frost - riven cliffs, cryoplanation plateaux, pseudocirques, block fields and many others. Almost 1000 measurements of joints were done. Cloose` s rosettes show systems of joints which prove tectonic system in the region and determine different mezoforms. Mapping brought some more results. Fluvial erosional and accumulative forms were classified as well as the anthropogenous forms. Powered by TCPDF (www.tcpdf.org)
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Textural record of phenocryst phases in porphyry dikes
Spurná, Eliška ; Špillar, Václav (advisor) ; Verner, Kryštof (referee)
Intrusive rocks allow the study of individual evolution phases of magma and furthermore support the interpretation of processes in complex magmatic systems. This thesis is dedicated to quantitative studies of textural analyses of two dyke systems of granitic porphyry in the Bohemian Massif, with supporting microscopic and micro-analytic studies of phenocryst and their compositional zoning. With the engagement of data analysis of crystal size distribution (CSD), clustering index and crystallinity. Both of the studied porphyry systems contain K-feldspar phenocrysts with intense zoning indicating a complicated growth history in the primary magma chamber. Textural records of both dyke systems indicate an in-situ dyke crystallization with a slight progression toward cumulates. 1
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Petrology and genetic relationships of alkaline intrusive rocks of the Roztoky Intrusive Complex
Mysliveček, Jakub ; Verner, Kryštof (advisor) ; Mlčoch, Bedřich (referee)
Roztoky Intrusive Center (33-28 Ma) is connected with tertiary volcanic activity in the territory of the Bohemian Massif (Czech Republic). It is located in the České středohoří volcanic complex on the tectonic line of the Ohře rift. The aim of this work was to petrologically describe local rocks and to verify the possible connection of the Roztoky Intrusive Center (RIC) with carbonatite magmatism, as could be suggested by the presence of alkaline rocks including their exotic types (essexites, monzodiorites, sodalitic syenites,…). It is assumed that there is a hidden carbonatite intrusion under the RIC caldera structure, which may also indicate geophysical manifestations of two hidden gravimetric minimas. In a detailed exploration of a drill core from the R-2 borehole from the 1960s, a petrographic rocks composition of a part of the caldera filling was described, including new find of xenolite of carbonatite in 286,5 m of R-2 borehole. By means of geochemical and micro-probe analyzes the well material including carbonatite was examined in detail. Carbonate mineralization with high REE contents was found in carbonatite, but also in the exocontact of the previously described silicocarbonatite (Rapprich et al. 2017). The discovery of carbonatite xenolite and the presence of minerals with high concentrations of...
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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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