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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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The record of sea-level changes, water circulation and sediment dispersion in the Upper Turonian hemipelagic strata of the Bohemian Cretaceous Basin
Hrnková, Magdalena ; Laurin, Jiří (advisor) ; Hladil, Jindřich (referee)
The Bohemian Cretaceous Basin was a sediment accumulation, which was deposited as an integral part of the central European epicontinental sea during the Late Cretaceous sea level highstand. It acted as a marine strait and was suited for preserving both nearshore coarse- clastic successions and hemipelagic deposits, allowing for the study of interplay between tectonics, eustatic sea level and paleoceanographic conditions. While the north-western part of the basin was extensively studied in the recent years, little information has yet been collected about the coeval along-shore environments. This thesis is aimed at bringing a new insight into these fine-grained deposits through a detailed lithological, multiproxy and time-series analysis investigation of the Late Turonian record in the Bch-1 drill core, Běchary, Czech Republic. The secular onset of carbonate-rich hemipelagic sedimentation coeval to the base of Teplice Formation is characterised by increased micrite content and changes in geochemical proxies, which are interpreted as changes in the pathway of clay distribution and silt source proximity, combined with elevated bioproductivity. Three orders of statistically significant variability were identified by time-series analysis of selected geophysical properties, two of which are carrying the...
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The record of sea-level changes, water circulation and sediment dispersion in the Upper Turonian hemipelagic strata of the Bohemian Cretaceous Basin
Hrnková, Magdalena ; Laurin, Jiří (advisor) ; Hladil, Jindřich (referee)
The Bohemian Cretaceous Basin was a sediment accumulation, which was deposited as an integral part of the central European epicontinental sea during the Late Cretaceous sea level highstand. It acted as a marine strait and was suited for preserving both nearshore coarse- clastic successions and hemipelagic deposits, allowing for the study of interplay between tectonics, eustatic sea level and paleoceanographic conditions. While the north-western part of the basin was extensively studied in the recent years, little information has yet been collected about the coeval along-shore environments. This thesis is aimed at bringing a new insight into these fine-grained deposits through a detailed lithological, multiproxy and time-series analysis investigation of the Late Turonian record in the Bch-1 drill core, Běchary, Czech Republic. The secular onset of carbonate-rich hemipelagic sedimentation coeval to the base of Teplice Formation is characterised by increased micrite content and changes in geochemical proxies, which are interpreted as changes in the pathway of clay distribution and silt source proximity, combined with elevated bioproductivity. Three orders of statistically significant variability were identified by time-series analysis of selected geophysical properties, two of which are carrying the...
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New achievements in sedimentary geology of the western part of the Bohemian Cretaceous Basin
Uličný, David ; Laurin, Jiří
Since the Late Cenomanian time the shallow seaway of the Bohemian Cretaceous Basin facilitated water-mass transfer across the nortehn part of the Bohemian massif. Marine currents flowing along the seawaz axis strongly influenced the deltaic deposition at basin margins. We interpret the narrowing of the seaway between the Czech and Saxonian parts of the basin as the main cause of vigorous tidal circulation. Acceleration of tidal currents in this region is reproduced also by numerical modelling of tidal circulation performed at the Imperial College (London) on the basis of our data.
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