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Variscan fluids of the Barrandian Lower Paleozoic: case study from the Žák's quarry at Velká Chuchle
Stárková, Petra ; Zachariáš, Jiří (advisor) ; Slobodník, Marek (referee)
Hydrothermal veins in the Paleozoic of the Barrrandian testify for fluid migration during diagenesis and/or epigenesis. A more detailed mineralogical and geochemical research of these veins has started since the end of the 20th century. The subject of a research included in this thesis is determination of conditions of formation of syntectonic calcite and quartz-calcite veins in the lokality called Žák's quarry in Velká Chuchle. This thesis is based on field determination of succession of hydrothermal veins and laboratory study of fluid inclusions in minerals as a basic tool for determination of temperatures during formation of veins. In total, there were distinguished four types/generations of calcite and quartz-calcite veins in Žák's quarry (from oldest to youngest): 1) veins of ,,beef calcite", 2) veins with flat crystals of smoky quartz located in joints perpendicular to bedding, 3) shear veins with calcite located in the big fold, 4) a big calcite vein with tectonic striae spatially bound to significant local fault. Veins have thickness aproximatelly from 1 mm to about 15 cm. By the way, veins of ,,beef calcite" are characteristic by orientation of prolonged grains of calcite in the direction orthogonal towards to the plane of vein. The microscopic study of fluid inclusions revealed presence of...
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Conditions of dolomitization at selected localities of the Barrandian
Novotný, Petr ; Zachariáš, Jiří (advisor) ; Suchý, Václav (referee)
Research on dolomitic limestones and dolomites from selected localities of the Barrandian, stratigraphically related to the Scyphocrinites Horizon near the Silurian-Devonian boundary, showed the occurrence of two distinct types of dolomite - diagenetic and epigenetic - differing in petrography and genesis. The diagenetic dolomite is quantitatively predominant. It is finely to moderately coarsely grained with crystal size from 20 μm to 450 μm. Crystals of this dolomite form mostly xenotopic and hypidiotopic textures (occasionally even idiotopic). This type of dolomite formed at low temperature and depth by recrystallization of a carbonate mud during early diagenesis, or during subsequent deeper burial. It is also possible that it originated from recrystallization of previously formed syngenetic dolomite. Fine texture of the diagenetic dolomite is a proof of fast dolomitization and of formation of numerous crystallization centers. Very fine-grained variant of dolomite was also detected (forming aphanotopic texture, size of crystals below 0,002 mm). The epigenetic dolomite, also known as baroque or saddle dolomite, is less common than the former one. It forms white, milky-turbid or clear crystals of large dimensions (0.8 - 3.1 mm). The shapes of these crystals are conspicuous, variously twisted,...
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Variscan fluids of the Barrandian Lower Paleozoic: case study from the Žák's quarry at Velká Chuchle
Stárková, Petra ; Zachariáš, Jiří (advisor) ; Slobodník, Marek (referee)
Hydrothermal veins in the Paleozoic of the Barrrandian testify for fluid migration during diagenesis and/or epigenesis. A more detailed mineralogical and geochemical research of these veins has started since the end of the 20th century. The subject of a research included in this thesis is determination of conditions of formation of syntectonic calcite and quartz-calcite veins in the lokality called Žák's quarry in Velká Chuchle. This thesis is based on field determination of succession of hydrothermal veins and laboratory study of fluid inclusions in minerals as a basic tool for determination of temperatures during formation of veins. In total, there were distinguished four types/generations of calcite and quartz-calcite veins in Žák's quarry (from oldest to youngest): 1) veins of ,,beef calcite", 2) veins with flat crystals of smoky quartz located in joints perpendicular to bedding, 3) shear veins with calcite located in the big fold, 4) a big calcite vein with tectonic striae spatially bound to significant local fault. Veins have thickness aproximatelly from 1 mm to about 15 cm. By the way, veins of ,,beef calcite" are characteristic by orientation of prolonged grains of calcite in the direction orthogonal towards to the plane of vein. The microscopic study of fluid inclusions revealed presence of...
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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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Limestones of Český kras and their use for hydraulic limes and natural cements
Kozlovcev, Petr ; Kuchařová, Aneta (referee) ; Přikryl, Richard (advisor)
ii Summary This bachelor thesis is focused on the possible use of limestones from the Český kras area for the preparation of alternative inorganic binders, namely for hydraulic limes and natural cements. In the introductory chapters, the geology of Český kras is described. Silurian and Devonian beds make the most important lithostratigraphic members. Then, the history of limestone exploitation and processing is explained. It is followed by the petrographical characteristic of limestone - its mineralogical and chemical composition, the structure and the texture, the classification, the genesis and the diagenesis. Major part of the thesis focuses on inorganic binders - their basic characterization and evaluation. Limestones are discussed from the point of their general use in the industry. The limestones from the Český kras area are analyzed based on their chemical composition (based on the previously reported data) and evaluated for the potential use for burning of hydraulic limes and natural cements.
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Lower Cretaceous in the Munella Mountains (Mirdita Zone, northeastern Albania)
Peza, Luftulla Hasan ; Marku, D.
The Munella Mountain is located in the Mirdita area, in the northeastern part of Albania. Berrisian, Valanginian deep-water flysch deposits. Unsorted breccias, including large blocks of ophiolites and Triassic limestones lie at the base of the Berriasian. Marls, sandstones, conglomerates with rare limestone intercalations characterize the upper part of the Berriasian. Sandstones and marls with abundant molluscs form the base of the Barremian-Aptian deposits. The highhest part of the section consists of platform limestones in Urgonian facies. An interruption in sedimentation during the Hauterivian was caused by the Mirditean orogeny.
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