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Cave of the Krkonoše National Park: cave fill and speleogenesis
Bosák, Pavel ; Tásler, R. ; Šťastný, Martin ; Hercman, H. ; Mikysek, Petr ; Pruner, Petr ; Kdýr, Šimon ; Matoušková, Šárka ; Rohovec, Jan
Sub-/vertical phreatic channels dominate in original cave morphologies together with ceiling half-channels, scallops and ceiling cupolas. Infiltration cave sediments are composed of lutitic component with some coarser authochthonous admixture. Sediments were locally re-distributed by intensive drip from open fissures. According to clay and heavy minerals, the primary source was in weathering products of crystalline rocks, mature and immature or polycyclic mixed in different proportions. No allogenic sediments were detected. Speleothem dating indicates, that caves were filled and exhumed several times, partially or fully. Normal polarization of samples proved the deposition within the Brunhes Chron (<773 kyr). Speleothems and rare paleontological remains date clastic sediments to >400 kyr. Speleothems crystallized mostly during interglacials, but also in cold and extremely cold periods in glacials (MIS 2, MIS 6c to 6a, MIS 8b, MIS 10c to 11a). Tectonical near-surface rock fissuration and corrosion substantially contributed to cave re-shaping by rock falls. Cryogenic processes modified the morphology of cave walls and damaged speleothems. Mostly ascending speleogenesis took part in substantial depths under the surface without any link to the present morphology. Present near-surface position of most of caves reflects the gradual uplift during younger tectonic phases and incision of river systems.
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Geochemical and isotopic dating of floodplain sediments
Nováková, Tereza ; Mihaljevič, Martin (advisor) ; Borůvka, Luboš (referee) ; Rohovec, Jan (referee)
River systems are the most widespread sedimentary environment in many European countries and can be hence used for study of historical development of contamination and for evaluation of the anthropogenic impact influence at the local or regional level. The study of river sediments, however, is complicated by changes of channel morphology and sedimentation dynamics and redeposition of old sediments, whether caused naturally (flood events) or by human impact (land use changes or building of water management structures), which leads to deposition of various sedimentary facies. Identification of sedimentary facies within floodplain fill is hence necessary - character (lithology) of deposited facies influences the spatial distribution of pollutants within floodplains. Suitable sampling sites strategy and chemostratigraphic correlations of depth profiles guarantee a correct interpretation of obtained data. However, in many countries, there are still no legislative tools or universal methodology for contamination assessment respecting natural variability of sedimentary records. Regional contamination during the last centuries and identification of local pollution sources of risk elements (Pb , Zn , Cu , ...) and magnetic particles have been studied in the sediments of the Morava River, in the area between...
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