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Paleozoic glaciation as an analog for Quaternary glacial cycles?
Kubíček, Martin ; Laurin, Jiří (advisor) ; Laibl, Lukáš (referee)
This bachelor thesis is focused on the comparison of the two main glacial periods of the Phanerozoic, the Late Paleozoic Ice Age and the Cenozoic Ice Age including Pleistocene. The main goal of the thesis is to compare the factors of glaciation and their controlling mechanisms on short and long-term scales, and the basic features of the Earth's circulation. Last but not least, the evaluation of unresolved questions and consideration of the possibility of using data from the Cenozoic, which point to a very complex behaviour of the climate system components. In both periods compared, the main climate driver appears to be the atmospheric greenhouse gas content. Another common feature is the declining trend in temperature, manifested initially by a less significant and ephemeral glaciation during the Upper Devonian, Eocene and Oligocene. The transition to the coldest phases with the lowest average temperature and the largest ice volume is characteristic. Based on CO2 content, amplitude of glacioeustatic oscillations or Milankovitch cycles, a sequence of several glaciation events in the Serpukhovian to Sakmarian interval can be considered as an analogue of the Pleistocene. The difference from the Pleistocene glaciation is presence of a large number of glaciation centres in the Gondwana area. Some...
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Paleoenvironmental record of carboniferous lacustrine deposits of central and western Bohemian basins: analysis and korealiton of mineral and biogenic proxies
Lojka, Richard ; Hradil, David (advisor) ; Hladil, Jindřich (referee) ; Janočko, Juraj (referee)
Ph.D. thesis represents summary of multidiciplinary palaeoenvironmental and palaeoclimatic research of the most significant Late Pennsylvanian lacustrine horizon of the central and western Bohemian basins - the Malesice Member of the Slaný Formation. Two cores from new shallow drills, situated 80 km apart, were analysed. Multidisciplinary approach is based on description of lamination structure and periodicity; mineral and isotopic composition of autigennic carbonates, namely siderite; compositiona of detrital minerals including clay mineral assemblages; and composition of autochthonous and allochthonous organic particles including palynospectra. Detailed analysis of drill cores lead to the identification of individual phases of lake development linked with lake-level fluctuation and water-column stratification, which were driven by a sume of precipitation and its seasonal distribution. Changes in precipitation also affected compostion and density of vegetational cover in the lake surroundings, weathering intesity of source rocks and degradation of organic matter in the drainage basin, and so precipitation affected final grain-size and composition of detrital material deposited in the lake. Beside common environmental signatures at both studied sites, there are also significant...
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