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Oyster bioherms in the Bohemian Cretaceous Basin
Rantuch, Jakub ; Košťák, Martin (advisor) ; Frank, Jiří (referee)
Frustration from shape and size variability of oyster's species Rhynchostreon suborbiculatum (Lamarck) is long known phenomenon. In current state of his systematic it is not possible to consider it fully satisfying. Is it is shown in study of genus Gryphaea by Jones and Gould (1999), that application of modern analytical methods, undoubtly lightens long-darkned places of evolution process. Idea of Videt and Neraudeau (2003), that shape variability of Rhynchostreon suborbiculatum (Lamarck) probably also mirrors heterochronic processes, introduces inspirative and good foundation for future research in this field. Occurence of this oyster is proved from huge range of sites in Bohemian Cretaceous Basin area. It is combination of rich occurance, unique preservation and variability of lithological settings, which gives us unique starting point for next step to solve significant problem. Based on population analyses consisting of biometrical studies supported by oxygen isotope analyses, in future, it will be possible to reach sufficient conclusions of this issue, and progress in our knowledge.
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Methodology for separation and isotope analysis of magnesium in selected geomaterials
Francová, Michaela ; Farkaš, Juraj (advisor) ; Chrastný, Vladislav (referee)
An efficient methodology for separation of magnesium from different geomaterials was developed in order to determinate their isotopic composition. This methodology with 100% yield is suitable for high precision analysis of Mg isotopes by multi collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Three separate stages of ion-exchange chromatography were carried out in ultra-trace laboratory equipped with laminar flowbox using cation exchange resin, AG50W-X12 and chemicals of ultrapure quality. Variations in samples 26 Mg/24 Mg and 25 Mg/24 Mg ratios are expressed as δ26 Mg and δ25 Mg units, which are deviations in parts per 103 from the same ratio in DSM3 Mg standard. The robustness of the technique was assessed by replicate analyses of magnesium standards Cambridge 1 versus DSM3. The long term repeatability of the Mg isotope ratio measurements of Cambridge 1 against DSM3 using this technique is -2.577 ± 0.10‰ on δ26 Mg and -1.328 ± 0.06‰ on δ25 Mg at 95% of confidence (2σ). Delta 26 Mg in five natural standard samples was measured in order to validate a quality of measurement in two different laboratories: Czech Geological Survey, Prague, Czech Republic and GFS Potsdam, Research centre for geoscientist, Potsdam, Germany. The results measured in this study (laboratory of CGS) are...
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Oyster bioherms in the Bohemian Cretaceous Basin
Rantuch, Jakub ; Košťák, Martin (advisor) ; Frank, Jiří (referee)
Frustration from shape and size variability of oyster's species Rhynchostreon suborbiculatum (Lamarck) is long known phenomenon. In current state of his systematic it is not possible to consider it fully satisfying. Is it is shown in study of genus Gryphaea by Jones and Gould (1999), that application of modern analytical methods, undoubtly lightens long-darkned places of evolution process. Idea of Videt and Neraudeau (2003), that shape variability of Rhynchostreon suborbiculatum (Lamarck) probably also mirrors heterochronic processes, introduces inspirative and good foundation for future research in this field. Occurence of this oyster is proved from huge range of sites in Bohemian Cretaceous Basin area. It is combination of rich occurance, unique preservation and variability of lithological settings, which gives us unique starting point for next step to solve significant problem. Based on population analyses consisting of biometrical studies supported by oxygen isotope analyses, in future, it will be possible to reach sufficient conclusions of this issue, and progress in our knowledge.
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