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Paleomagnetism and magnetomineralogy of rocks from the Bohemian Massif and Tethyan Realm
Schnabl, Petr ; Pruner, Petr (advisor) ; Hrouda, František (referee) ; Petrovský, Eduard (referee)
Mgr. Petr Schnabl - Dissertation Paleomagnetism and magnetomineralogy of rocks from the Bohemian Massif and Tethyan Realm Abstract The thesis deals with paleomagnetic and rock magnetic properties of Silurian/Devonian and Jurassic/Cretaceous limestones, Paleogene/Neogene basaltic rocks and altered Silurian basalts. The main goal is to determine the history of the Earths' magnetic field from the Silurian to the present. Two lithostratigraphic formations are defined in the Jičín volcanic field on the basis of volcanology, paleomagnetism and radiometric dating. The Trosky Formation (24.6?/18.3 - 15.7 Ma) is composed of several Strombolian-type volcanoes, while the Kozákov Formation (5.2 - 4.6 Ma) is represented by effusive products with a crater vent of a single giant volcano. One Pliocene (4.3-3.3 Ma) and two Pleistocene phases (2.6 -2.1 Ma and 1.8 - 1.1 Ma) of volcanic activity Magnetostratigraphy is a very important tool for the definition of the J/K boundary. The boundary between the Crassicolaria and Calpionella zones is present within geopolarity zone M19n. The boundary between the ammonite zones Jacobi and Durangites also lies close to this point. Paleomagnetic directions of Silurian and Devonian rocks in the Bohemian Massif are very difficult to interpret and have been studied as a challenging problem...
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Experimental study of Palaeozoic limestones of the Barrandian and their possible use for burning of hydraulic limes and natural cement
Kozlovcev, Petr ; Přikryl, Richard (advisor) ; Vavro, Martin (referee)
54 Summary In this experimental study, selected Devonian limestones of the Prague Basin (i.e. samples from the historic quarry of Branické skály) were examined to find their suitability for production of hydraulic limes or for natural cement. Four representative samples of the dvorecko-prokopské limestone were sampled in the form of blocks weighing approximately 10 kg each, from the layer of the quarry wall that had been chosen based on literature research. A detailed mineralogical-petrographic examination of samples was the first step, in an attempt to obtain their mineralogical composition, microstructure and texture. Samples were analysed by polarizing microscopy and cathodoluminescence of thin sections, and X-ray diffraction of insoluble residues determined by treatment with both the hydrochloric acid and the acetic acid solution. Mineralogical composition of the insoluble residuals was illite, kaolinite, quartz and Na-plagioclase (albite). Two samples contained among above mentioned mineral phases also chlorite. The utility of studied limestones for the production of hydraulic binders (hydraulic limes and natural cement) was derived from both the calculations based on obtained chemical analyses (included standard cement and lime indexes and modules) and the firing experiments. The firing experiments...
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Taxonomic position of the species Bactroceras sandbergeri (Barr.,1867) from the Czech Ordovician
Aubrechtová, Martina ; Marek, Jaroslav (advisor) ; Turek, Vojtěch (referee)
Taxonomic position of the cephalopod Bactroceras sandbergeri (Barr., 1867) from the Ordovician of the Prague Basin was subjected to wide discussions and disputes in the past. The species was first classified within the genus Bactrites. Later, a separate, monotypic genus Eobactrites was defined. At present, the species is assigned to the genus Bactroceras. It belongs to the family Baltoceratidae, the genera of which are supposed to represent the oldest orthoceridans. The order Orthocerida is one of the most successful and most diversified cephalopod groups of the Paleozoic Era. In this thesis, a revision of Bactroceras sandbergeri has been made after a detailed study of about one hundred specimens. Attention was paid to those features, that are missing in the original species descriptions or that were neglected in the past. Special attention was paid mainly to muscle scars, structure of the siphuncle and morphology of the embryonic shell. The embryonic shell was originally described as Tretoceras parvulum Barrande, 1868. In addition, Orthoceras naufragum Barrande, 1870 was synonymized with the studied species and the species Orthoceras interpolatum Barrande, 1870 was assigned to the genus Bactroceras. Key words: Cephalopoda, Ordovician, Czech Republic, Barrandian area
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Early Devonian Foraminifera from the Prague Formation
Vaněčková, Anna ; Holcová, Katarína (advisor) ; Tonarová, Petra (referee)
Lower Devonian foraminifera are known from only a few localities globally and thus are not much investigated. The taxonomy, as well as further use of this group is insufficiently known. One of the main areas of research of foraminifera is the Barrandian area in the Czech Republic. This thesis follows previous studies of this territory but focuses particulary on the Prag formation, which has proven to be rich in foraminifera communities. Taxonomic studies were conducted at two Lower Devonian sites, namely the Na Stydlých vodách quarry and the Požáry quarry. The study showed that foraminifera communities described from the Na Stydlých vodách quarry were dominated by the following genera: Hyperammina, Colonammina and Tolypammina. The highest abundance was recorded at the transition of dvorecko-prokopské limestones and řeporyje limestones and in dvorecko-prokopské limestones. At the Požáry quarry, the communities were dominated by tubular genera of Tolypammina, Hyperammina and Bathysiphon and spherical genera of Lagenammina and Colonammina. The abbundance of Colonammina is unusually high, the genus has been described rarely from other parts of the world so far.
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Irone ores from the Krušná hora (hill)
Nič, Martin ; Marek, Jaroslav (advisor) ; Čáp, Pavel (referee)
Krušná Hora near Nový Jáchymov belongs in Barrandian area to one of the most important localities with the occurrence of Ordovician sedimentary iron ores. Rich reserves of iron ore and easy access to this area was known and used since many centuries ago. Use of deposits laid the foundation for the rich history of mining and metallurgy in Křivoklátsko. The work is divided into two thematic parts. The geological section is devoted to the construction of tectonic bearings, its stratigraphy, mineralogy, petrology, lithology and paleontological finds. Briefly describes the development of this sedimentation area. Self-described history of the geological survey. The history of the use of bearings is described in the second part, which is divided according to individual companies engaged in mining there. Particular attention is paid especially to companies conducting mining during the 20th century. Self-described termination of mining and mine disposal. Attention is paid to the technical equipment of the mine and the current state of the remains of the mining activities.
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