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Lithology, geochemistry and metamorphic evolution of northern Hammar Domain (East-African Orogeny)
Gashe, Negessa Gonfa ; Verner, Kryštof (advisor) ; Racek, Martin (referee)
in English The studied part of the Hammar Domain is composed of the Neoproterozoic basement rocks belonging to the Southern Ethiopian Shield (SES), partly covered by volcanic and volcanosedimentary deposits of the Main Ethiopian Rift (MER). The high-grade migmatite to migmatized biotite paragneiss and amphibolites were intruded by numerous peraluminous granite and granodiorite bodies and gabbros of metaluminous composition. The results of U/Pb zircon dating of granodiorite yielded at 507.7 ± 3.2 Ma, which is interpreted as the age of magma emplacement and crystallization. The P-T estimation reveal the peak P-T conditions at ca. 1.21 to 0.88 GPa and ca. 842 to 700 řC which were followed by retrograde part P-T path (from ca. 0.84 to 0.12 GPa) with decrease of temperature from ca. 700 to 464 řC. The emplacement of gabbro in syn-tectonic settings took place at P = ca. 0.87 to 0.93 GPa and T ca. 650 řC reflecting magma emplacement to ca. 30 km in depth. Next, the syn- to post- tectonic emplacement and crystallization of biotite and amphibole-bioitite granodiorite reveal P = 0.27-0.52 GPa and T ca. 720-836. The events described above were associated with the latter period of the East-African Orogeny, which resulted in overall consolidation of the Gondwana continent.
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Response of selected rivers of the Bohemian Massif to lithological and structural conditions
Flašar, Jan ; Nývlt, Daniel (advisor) ; Kalvoda, Jan (referee)
Three groups of streams were selected in the area of the Bohemian Massif: the Berounka river with its source streams; the Vltava river with its tributaries the Malše and the Lužnice; the Labe river with its tributaries the Cidlina, the Bystřice and the Javorka. The lithological and tectonical influences to several parameters of the streams were studied. These parameters include: stream gradient, orientation of the stream and sinuosity of the stream. Data were obtained from digital elevation models, aerial photographs, topographical and geological maps. The longitudinal profiles of the streams (in the combination with geological cross-sections), the SL indexes and the gradient/sinuosity graphs were created on the basis of the obtained data. These tools were used for evaluation of the influence of lithology and the tectonics to the streams. The evolution of the streams and the stream-groups was evaluated and compared as well. A strong influence of lithology on the stream gradient was found on most of the analysed streams. The tectonic situation, on the contrary, had strong influence on the orientation of the streams, especially in the resistant rocks. Also, there were selected areas, where was a higher probability of quaternary vertical movements influencing the streams (mountainous areas of the Novohradské...
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Correlation of abiotic proxies in Holocene lacustrine sediments of Peri-Atlantic Arctic
Roman, Matěj ; Nývlt, Daniel (advisor) ; Sedláček, Jan (referee)
The peri-Atlantic Arctic, one of the most sensitive components of the Earth climate system, experienced pronounced climatic fluctuations during the Holocene. Several external forcings were considered responsible for these variations, including decline of insolation on the Northern Hemisphere, changes in distribution of land ice mass, explosive volcanism, or changes in atmospheric and oceanic circulation. In order to explore the driving mechanisms of the peri-Atlantic Arctic environmental variability, three sites located in different parts of the region were selected for palaeoenvironmental reconstructions with focus on extracting the climatic information. With this intention, sedimentary cores from i) Lake Garmaksla, Central Svalbard, ii) Jarfjorden, northeastern Norway, and iii) Kobbefjord area, southwestern Greenland, were retrieved and subjected to multi-proxy investigation. The absolute chronostratigraphic framework was established by comprehensive radiocarbon (14 C) and short-lived radioisotopes (210 Pb, 137 Cs) dating. Further analyses include measurements of magnetic susceptibility, grain size distribution, element composition by means of X-ray fluorescence (XRF), and elements bound to organic matter, i.e. organic carbon, nitrogen, sulphur and biogenic silica. The relationships between the...
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Response of selected rivers of the Bohemian Massif to lithological and structural conditions
Flašar, Jan ; Nývlt, Daniel (advisor) ; Kalvoda, Jan (referee)
Three groups of streams were selected in the area of the Bohemian Massif: the Berounka river with its source streams; the Vltava river with its tributaries the Malše and the Lužnice; the Labe river with its tributaries the Cidlina, the Bystřice and the Javorka. The lithological and tectonical influences to several parameters of the streams were studied. These parameters include: stream gradient, orientation of the stream and sinuosity of the stream. Data were obtained from digital elevation models, aerial photographs, topographical and geological maps. The longitudinal profiles of the streams (in the combination with geological cross-sections), the SL indexes and the gradient/sinuosity graphs were created on the basis of the obtained data. These tools were used for evaluation of the influence of lithology and the tectonics to the streams. The evolution of the streams and the stream-groups was evaluated and compared as well. A strong influence of lithology on the stream gradient was found on most of the analysed streams. The tectonic situation, on the contrary, had strong influence on the orientation of the streams, especially in the resistant rocks. Also, there were selected areas, where was a higher probability of quaternary vertical movements influencing the streams (mountainous areas of the Novohradské...
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