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Volcanics of the southeastern flank of the barrandian Neoproterozoic in vicinity of Dobříš
Mráček, Michal ; Kachlík, Václav (advisor) ; Stárková, Marcela (referee)
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. Some lenses of lava and volcanoclastic breccia and minor layer spilite were newly discovered, areal extent of some cherts bodies and basaltic dykes were modified. Basalts, andesites and dacites bodies have been reclassified against the basic geological map of 1:25 000 (Havlíček, 1985; Mašek, 1987). Basalts in the Havlíček's (1985) map actually represent a very fine-grained rhyolites (ignimbrites) with disseminated ore minerals with layers of pyroclastic rocks (ignimbrites, volcanoclastic breccia). Areal extent of andesites and dacites bodies were modified and new body of trachyandesite was detected. Extremely fast cooled grained textures and series of features corresponding to welded tuff (ignimbrites) shows that the tuffs were deposited in...
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Neovolcanic Rocks of the SW part of the Most Basin in the area of Tušimice power plant open pit
Sobotka, Martin ; Kachlík, Václav (advisor) ; Novotný, Tomáš (referee)
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...
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Neovolcanic Rocks of the SW part of the Most Basin in the area of Tušimice power plant open pit
Sobotka, Martin ; Kachlík, Václav (advisor) ; Novotný, Tomáš (referee)
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...
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Volcanics of the southeastern flank of the barrandian Neoproterozoic in vicinity of Dobříš
Mráček, Michal ; Kachlík, Václav (advisor) ; Stárková, Marcela (referee)
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. Some lenses of lava and volcanoclastic breccia and minor layer spilite were newly discovered, areal extent of some cherts bodies and basaltic dykes were modified. Basalts, andesites and dacites bodies have been reclassified against the basic geological map of 1:25 000 (Havlíček, 1985; Mašek, 1987). Basalts in the Havlíček's (1985) map actually represent a very fine-grained rhyolites (ignimbrites) with disseminated ore minerals with layers of pyroclastic rocks (ignimbrites, volcanoclastic breccia). Areal extent of andesites and dacites bodies were modified and new body of trachyandesite was detected. Extremely fast cooled grained textures and series of features corresponding to welded tuff (ignimbrites) shows that the tuffs were deposited in...
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Petrology and geochemistry of Devonian volcanic rocks in the southern part of the Šternberk-Horní Benešov Belt
Řihošek, Jaroslav ; Kachlík, Václav (advisor) ; Přichystal, Antonín (referee)
Šternberk-Horní Benešov belt (SHB) is built by Devonian and Lower Carboniferous rocks located between Culmian Eastern Jeseníky and Western Jeseníky nappes. As the SHP is located in the Low Jeseníky Mountains , it is a part of Rhenohercynian zone of European Variscides. The southern part of SHB is built by a volcanic complex of intrusive rocks, lavas and volcanoclastic rocks with intercalated beds of Stínava- Chabičov shales. Alkaline volcanism in Rhenohercynian zone was earlier interpreted as a result of extension in back-arc basin. Structural measurements of this study proved, that volcanosedimetary succession (situated north eventually northward) of Šternberk) is a tectonic slice. This slice was dragged out on the base of the Culmian greywacke nappe during the Variscan orogeny. Firstly the slice was thrusted northeastwards over the body of younger Culm greywacke. After that, the stack of nappes (including the Devonian volcanic rocks ) was sheared in dextral transpressional regime. The field works also indicated, that the Devonian vol- canic complex was tectonically separated from its stratigraphic footwall and hanging- wall. Volcanic rocks gradually built an elevation, eventually reaching the sea level. Anal- ysis of volcanic facies proved that the most of volcanoclastic rocks was deposited near...
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Comparisoon of leucogranitoids from divergent and convergent tectonic settings
Janoušková, Renata ; Kachlík, Václav (advisor) ; Trubač, Jakub (referee)
Granitoid belong to one of the most important rock type in the continental crust, especially in the orogenic belts. We classify them into several basic types, accrording to their mineral composition, petrographic and petrogenetic features, chemical composition and geotectonic environment of their origin. Genetically very interesting type of granitoids, genesis of which is widely discussed in the present literature, are leucogranitoids. They represent, with exception of very old Archaic granitois of tonalite-trondhjemite-granodiorite suite products of extreme differenciation of magmas, which are derived from various crustal and mantle souces, or originate by magma mixing and mingling processes and by reaction of melts with country rocks during magma ascent. According to geotectonic setting of their origin, leucogranitoids can be divided into leucogranitoids, which originate on divergent plate margin, especially on the mid-ocean ridges and in the leucogranitoid, which originate on destructive plate margins - island arcs or active continental margins. The submited work presents petrographic and geochemical characteristic of individual leucogranitoids types, characterizes sources of magmas, tectonic setting and major differentiation processes as partial melting of water and fluids saturated rocks,...
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Variscan and pre-Variscan tectonometamorphic processes in external zones of the Bohemian Massif-examples from the Krkonoše-Jizera Massif and the Letovice Complex
Žáčková, Eliška ; Konopásek, Jiří (advisor) ; Kachlík, Václav (referee) ; Kryza, Ryszard (referee)
Tectonometamorphic processes in external zones of the Bohemian Massif during Lower Palaeozoic were studied in this work. The studied areas cover the northeastern part of the Saxothuringian Domain (Krkonoše-Jizera Massif) and the Letovice Complex located between the western margin of the Moravian Zone and the eastern edge of the Moldanubian Domain. Evolution of both these units was influenced by Early Palaeozoic rifting and Devonian- Carboniferous Variscan orogenesis. In the Saxothuringian Domain, Variscan processes were connected with subduction of the Saxothuringian ocean below the easterly exposed core of the Bohemian Massif and resulted in the development of high-pressure low-temperature metamorphism. Thermodynamic modelling of metamorphic evolution in metapelites from the Krkonoše-Jizera Massif suggests that these rocks record peak pressure conditions of ≥18-19 kbar at 460-520řC followed by isothermal decompression to pressures of 10.5-13.5 kbar and final decompression to <8.5 kbar and <480řC. The calculated peak P-T conditions indicate a high-pressure/low-temperature apparent thermal gradient of ~ 7-7.5 řC km-1 . Laser ablation inductively coupled plasma mass spectrometry (ICP-MS) isotopic dating and electron microprobe chemical dating of monazite give ages of 330 ±10 Ma and 328 ±6 Ma,...
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