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Dating of radioactive mineral springs of the Krkonoše-Jizera crystalline by 230Th/234U method
Fanta, Martin ; Goliáš, Viktor (advisor) ; Mizera, Jiří (referee)
The isotopes 238 U, 234 U and 230 Th, as members of the uranium-radium decay chain, are fractionated in the environment by changes of geochemical conditions, and they can be used for dating of recent or past geochemical processes in the Quaternary. Samples of water with uranium and of water-activated solids were taken of radioactive mineral water springs at two study sites in the area of Krkonoše-Jizera crystalline complex: Svatý Vojtěch (St. Adalbert) in Horní Malá Úpa, and Bukový Pramen in the Těsný důl valley in Janské Lázně. Uranium was co-precipitated in field conditions with hydroxides of FeIII+ in 50-liter water samples of the radioactive springs. In the lab, uranium and thorium were separated from water precipitates, as well as from solid samples after their chemical decomposition, using chromatographic extraction agent UTEVA. All the three isotopes of interest emit alpha particles, and so their activities were measured by alpha spectrometry and expressed as 234 U/238 U and 230 Th/234 U ratios. As an internal standard, 232 U/228 Th was used. The resulting 234 U/238 U activity ratios of four water samples measured ranged from 1.0747 to 1.423. In twelve samples of solid phases activity ratios 234 U/238 U from 0.861 to 1.129 were determined. The 230 Th/234 U activity ratios form two distinct...
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Volcanism of Large Igneous Provinces in Earth's history; possible impacts on global ecosystem
Zajícová, Jana ; Holub, František (advisor) ; Rapprich, Vladislav (referee)
Large igneous provinces (LIPs) are huge accumulations of magmatic rocks originated during unusually short time and characterized by extremely high magma productivity. Among them, namely the continental flood basalts (traps) cover very extensive areas and may or may not be associated to rifting and breakup of continents. However, also highly voluminous oceanic plateaus were recognized and some authors count to LIPs even some other types of huge magmatic complexes. A large amount of gases is released with escaping magma, usually oxides of carbon, sulfur and nitrogen. These gases more or less have impact on the environment and thus also influence organisms. The formation of magmatic provinces repeated many times in the past. The best known are continental Deccan Traps in India and the most voluminous Siberian Traps. Oceanic LIPs are represented, e.g., by the Ontong Java Plateau in the west Pacific Ocean. There is a link in dating the emergence of large igneous provinces and mass extinctions. As an example, the largest known extinction at the end of Permian, which was broadly contemporaneous with the formation of the Siberian traps (approximately 250 Ma ago), or extensive loss of species on the boundary of Cretaceous / Tertiary, which coincides with the formation of the Dekkan in India (before about 65...
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Sestavení lokálních letokruhových chronologií na základě dendrochronologického datování roubených hospodářských staveb z jihovýchodní Moravy
Tetur, Vladan
The subject of the thesis is to determine the age of individual farm buildings by means of dendrochronological analysis and compilation of local tree-ring chronologies of the given tree species. The work describes a detailed procedure for dendrochronological dating from sampling and preparation of samples through measurements to their dating. The work also deals with the use of individual trees in structures. The oldest building is a barn from the village of Vrbětice made of beech, whose design elements were dated to 1766/1767. On the other hand, the youngest building can be labeled as a fruit dryer from the village of Pradlisko. Taken oak samples from the construction managed to date to 1944/1945. The most represented tree species in the surveyed farm buildings were beech and oak. Other trees are represented in very small numbers to determine their importance in the structure. The oak elements were used in the construction mainly for foundation sills and the beech elements for the construction of the walls. With regard to the number of samples of individual trees, two local ring-shaped chronologies were created. The beech chronology consists of ring-shaped curves of 29 samples taken from historical structures and 22 ring-shaped curves from live trees, with a non-interconnected section of approximately 93 years between the two parts. Combining these two parts, the chronology would be able to cover more than 300 years (1690–2013). Oak local chronology is made up of ring-shaped curves of 30 samples from the surveyed objects and covers the period from 1700 to 1900. Since there is no beech chronology for the Czech Republic, it is a great contribution to making the basic beech chronology for this region, where beech is the most used wood in buildings. The work contributes to the building of beech chronology.
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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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Determination of the age of secondary uranium minerals using 230Th/234U in selected localities of the Bohemian massif
Roll, Michal ; Goliáš, Viktor (advisor) ; Mizera, Jiří (referee)
This thesis is focused on prominent uranium deposits in Czech Republic and their secondary uranium mineralization. Main goal of this thesis is to analyze collected minerals and to determine their ages. Next step is to prove or disprove hypothesis that this secondary uranium minerals are products of Quaternary glacier weathering. As a suitable analytical method, an alpha spectrometry was used and the age was calculated by 230 Th/234 U ratio. Firstly, chosen methodology was verified with admixture of reference material PU1 (Přibram uraninite) in secular equilibrium and internal standard, both with known activity. Analyzed spectra confirmed that some of the samples lay on the very edge of datability, especially in case of PL1 and GF1, both samples are very young, so they easily could be products of anthropogenic activity (changed environment due to mining works). On the other hand, in case of sample GF3, the age was successfully determined, although it is also quite young phase. In case of samples ME3, ME4 and ME6 was used threshold dating method, because they were considered to be too old for age calculation. The rest of the samples chosen for age determination was analyzed without further complications. Based on the age and geological setting, samples GF3 (3 725 ± 845 years), JE1 (10 655 ± 1 795...
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Dating of radioactive mineral springs of the Krkonoše-Jizera crystalline by 230Th/234U method
Fanta, Martin ; Goliáš, Viktor (advisor) ; Mizera, Jiří (referee)
The isotopes 238 U, 234 U and 230 Th, as members of the uranium-radium decay chain, are fractionated in the environment by changes of geochemical conditions, and they can be used for dating of recent or past geochemical processes in the Quaternary. Samples of water with uranium and of water-activated solids were taken of radioactive mineral water springs at two study sites in the area of Krkonoše-Jizera crystalline complex: Svatý Vojtěch (St. Adalbert) in Horní Malá Úpa, and Bukový Pramen in the Těsný důl valley in Janské Lázně. Uranium was co-precipitated in field conditions with hydroxides of FeIII+ in 50-liter water samples of the radioactive springs. In the lab, uranium and thorium were separated from water precipitates, as well as from solid samples after their chemical decomposition, using chromatographic extraction agent UTEVA. All the three isotopes of interest emit alpha particles, and so their activities were measured by alpha spectrometry and expressed as 234 U/238 U and 230 Th/234 U ratios. As an internal standard, 232 U/228 Th was used. The resulting 234 U/238 U activity ratios of four water samples measured ranged from 1.0747 to 1.423. In twelve samples of solid phases activity ratios 234 U/238 U from 0.861 to 1.129 were determined. The 230 Th/234 U activity ratios form two distinct...
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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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Volcanism of Large Igneous Provinces in Earth's history; possible impacts on global ecosystem
Zajícová, Jana ; Holub, František (advisor) ; Rapprich, Vladislav (referee)
Large igneous provinces (LIPs) are huge accumulations of magmatic rocks originated during unusually short time and characterized by extremely high magma productivity. Among them, namely the continental flood basalts (traps) cover very extensive areas and may or may not be associated to rifting and breakup of continents. However, also highly voluminous oceanic plateaus were recognized and some authors count to LIPs even some other types of huge magmatic complexes. A large amount of gases is released with escaping magma, usually oxides of carbon, sulfur and nitrogen. These gases more or less have impact on the environment and thus also influence organisms. The formation of magmatic provinces repeated many times in the past. The best known are continental Deccan Traps in India and the most voluminous Siberian Traps. Oceanic LIPs are represented, e.g., by the Ontong Java Plateau in the west Pacific Ocean. There is a link in dating the emergence of large igneous provinces and mass extinctions. As an example, the largest known extinction at the end of Permian, which was broadly contemporaneous with the formation of the Siberian traps (approximately 250 Ma ago), or extensive loss of species on the boundary of Cretaceous / Tertiary, which coincides with the formation of the Dekkan in India (before about 65...
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Geologický výzkum Antarktidy
Masarykova univerzita, Přírodovědecká fakulta, Brno ; Univerzita Karlova v Praze, Přírodovědecká fakulta, Praha ; Česká geologická služba, Praha ; Holub, František V. ; Kadlec, Jaroslav ; Svojtka, Martin ; Máčka, Zdeněk ; Jeřábek, Petr ; Žák, Jiří ; Lexa, Ondrej ; Klán, Petr ; Košler, Jan ; Mlčoch, Bedřich ; Nývlt, Daniel ; Mixa, Petr
Závěrečná zpráva popisuje výsledky čtyřletého projekt, kterých bylo dosaženo v jednotlivých dílčích úkolech: 1. Studium zdrojových oblastí a glacifluviálních a morénových sedimentů na ostrově James Ross ve vztahu k paleoklimatologickému a paleogeografickému vývoji oblasti; 2. Organické průmyslové polutanty - jejich koncentrace, chování a degradace v prostředí Antarktidy; 3. Geomorfologický výzkum kamenných ledovců, periglaciálních a paraglaciálních fenoménů na ostrově James Ross; 4. Podrobné geologické mapování území projektovaného biologického monitoringu; 5. Tektono-metamorfní vývoj hornin akrečního prizmatu Trinity Peninsula Group; 6. Magmatické stavby antarktického batolitu (sev. část Graham Land) a způsob jeho vmístění; Sedimentologický a geomorfologický záznam zalednění na ostrově James Ross a jejich korelace s vývojem zalednění v průlivu Prince Gustav.
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