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Correlation of tectonic evolution of the Blanice Graben and of late Variscan hydrothermal processes
Hübst, Zdeněk ; Zachariáš, Jiří (advisor) ; Pertold, Zdeněk (referee)
The Blanice graben represents about 200 km long N-S trending tectonic zone with minimal sinistral movement of about 17 km. Large number of hydrothermal ore deposits (eg. the Roudný gold deposit; or numerous small-sized deposits/districts of Ag-Pb-Zn ores - Stará Vožice - Ratibořské Hory or Rudolfov near České Budějovice). This thesis is focused on the northern and central part of the Blanice graben in between the villages Vlašim, Mladá Vožice and Chýnov. Much of the work is focused on the reconstruction of the structural evolution of the Roudný gold deposit. The thesis is aimed in the study of brittle deformation, namely in the study hydrothermal veins, intrusive dikes and in paleostress analysis of fault-slip data. In addition to field data, structural data were also excerpted from unpublished historical documents (reports, maps, underground documentation). At least two phases of brittle deformation were discriminated in the study area. Older phase corresponds to E-W to NW-SE oriented compression. The younger phase represents extension in the E-W to NE-SW direction. During the older phase, the oldest types of quartz veins (Q0 to Q2) formed at the Roudný gold deposit, while type Q3 veins at the same deposit formed during the younger phase. The younger tectonic phase also allowed formation of hydrothermal...
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Volumetric and electrostatic properties of water and their application to aqueous thermodynamics and mineral solubility at high temperatures and pressures
Hanková, Barbora ; Dolejš, David (advisor) ; Zachariáš, Jiří (referee)
Hydrothermal fluids are important mass and heat transfer agents in the Earth's crust and mantle. Aside from their transport role, the aqueous fluids act as reactants or products in rock environment during diverse processes ranging from partial melting, magmatic and metamorphic devolatilization. This study evaluates the effect of equations of state and thermodynamic data for aqueous species on prediction of mineral solubility in aqueous fluids at high temperatures and pressures employing the Helgeson-Kirkham-Flowers model (HKF). These calculations require: (i) volumetric properties of water; (ii) dielectric properties of water; (iii) aqueous species thermodynamic properties. A comparison of ten equations of state against the IAPWS scientific standard reveals that volumetric properties of water up to 1200 řC and 50 kbar are predicted within 5 %, except at low pressure (below 2 kbar), temperatures higher than 1000 řC, and the liquid-vapor equilibrium curve, particularly in the proximity of the critical point of water. The deviations of volumetric and electrostatic properties of water propagate into the mineral solubility calculations. For quartz and corundum these deviations lead to discrepancy in mineral solubility of up to half an order of magnitude for molal concentrations. These discrepancies...
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Principles of application of fluid inclusions for the study of hydrothermal mineralizations
Štrba, Martin ; Zachariáš, Jiří (advisor) ; Dobeš, Petr (referee)
The bachelor thesis is subdivided into two review parts and one experimental part. The first part focuses on petrography and microthermometric study of fluid inclusions. Petrography chapter lists genetic types of inclusions, and various mechanisms that determine their shape and digree of fill. Emphasis is placed especially on the microthermometric study of fluid inclusions. The phase changes in H2O - NaCl and H2O - CO2 - salts systems at low and high temperatures are described in detail. A separate chapter is dedicated to interpretation of microthermometric data and to their use in determination of pressure-temperature conditions of minerals formation. The second part of the thesis lists several examples of using the fluid inclusions in the study of hydrothermal deposits and in prospecting of ore deposits (Pb - Zn - fluorite deposits of Mississippi valley type, porphy - type, Cu - ores at Bingham). One chapter is dedicated to Bleïda deposit (Morocco), Kanmantoo deposit (Australia) and San Cristobal vein (Peru). This chapter discribes geology, mineralogy and fluid inclusion data of these deposits. Third, experimental, chapter deals with hydrothermal mineralization in the Ševětín quarry. It includes the regional geology of Ševětín massif, geology of the quarry and the mineralogy of hydrothermal...
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Secondary gold mineralization at Bezdružice area
Mladý, Tomáš ; Zachariáš, Jiří (advisor) ; Velebil, Dalibor (referee)
This thesis is focused on orogenic gold deposits and placer gold deposits. The first part describes predispositions for formation of orogenic gold deposits and their place in time and space. Next part of this thesis discusses mechanisms of formation of secondary gold deposits, so called placers. Practical part of this thesis is studying the sites in the neighbourhood of Bezdružice in West Bohemia - paleoplacer in sand quarry near municipality Křivce, grove with old mine works near municipality Nová Ves and the creeks which surround the grove from north and south. The aim of this thesis is to define whether the gold nearby Nová Ves originates in the Carboniferous paleoplacers which are in the proximity of old mines or if it comes from primary deposit and was formed close to cinnabar mineralization. Specimens were analysed under optical microscope and by energy dispersive system coupled with SEM. These analyses helped to distinguish gold flakes from the creeks of Nová Ves and the gold flakes from paleoplacer.
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Isotope alteration of carbonate component of Cretaceous sediments from xenolites and vicinity of selected neovolcanic bodies of the Jičín volcanic field
Konečný, Tomáš ; Zachariáš, Jiří (advisor) ; Trubač, Jakub (referee)
The diploma thesis deals with the study of stable isotopes of oxygen and carbon of Cretaceous rocks from the Jičín volcanic field. The aim of the thesis is to identify isotope alterations in Cretaceous sediments transported by basic magmas in the form of xenoliths and to determine the origin of oxygen and carbon of hydrothermal vein carbonates that penetrate the bodies of neovolcanites. The study is divided into two parts. The theoretical part summarizes in general the stratigraphy of the Czech Cretaceous Basin and Cenozoic volcanism of the Bohemian Massif, geochemistry of stable isotopes of oxygen and carbon and geology of studied localities in the Jičín volcanic field. The practical part presents a detailed isotope study of Hřídelec, Kulatý vrch, Zebín, Veliš and Kunětická hora localities. Cretaceous rocks from xenoliths in these neovolcanites show extreme variability in the isotopic composition of both carbon (from 0,15 to -11,1 ‰ V-PDB) and oxygen (from -5,4 to -22,9 ‰ V-PDB). They significantly exceed the variability of the isotopic composition of diagenetically altered Cretaceous rocks from the same area. The wide range of oxygen isotope composition is the result mainly of fluid temperature variability (approx. 300 - 20 řC), which isotopically altered Cretaceous sediments. Carbon isotope...
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Porphyry Cu-Au deposits in the world and in Mongolia
Yunden, Tuvshinbayar ; Zachariáš, Jiří (advisor) ; Pertold, Zdeněk (referee)
Copper played crucial roles throughout the history for at least 10,000 years and was an important part of the industrial revolution. Copper has specific chemical and physical attributes. Thanks to its abilities, copper is one of the most demanded metals in the industrialized world. Copper is widely used to produce various products, such as electrical and electronic products, construction, industrial equipment and other general products. Occurrence of Cu in the Earth's crust is around 50 ppm. Copper bearing minerals are discussed later, but Cu can be found in pure "native" form. Porphyry Cu deposits supply more than a half of world Cu production. Regions with the most abundant PCDs are the Andes of South American, North American Cordillera and southwestern Pacific region. Europe, Africa a central Asia host some significant deposits. Review-based bachelor thesis "Porphyry Cu-Au deposits in the world and Mongolia" discusses variety of aspects of global porphyry deposits regarding their metal association, geology, global abundance, and genesis in the first part. Next part discusses briefly the Mongolian copper production and regional geology and final part discusses characteristics of two Mongolian gold-rich porphyry Cu deposits, Oyu-Tolgoi and Kharmagtai.
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Mineralogy and genesis of gold ores hosted by porphyry dykes at Petrov and Bohuliby
Petrov, Ivan ; Zachariáš, Jiří (advisor) ; Strnad, Ladislav (referee)
This bachelor thesis is focused on mineralogy and genesis of Au-bearing ores in southwestern part of the Jílové ore district, in between Petrov and Bohuliby. Crystallization sequence of hydrothermal minerals was identified by textural relationships of mineral phases. Arsenopyrite and chlorite thermometry suggest formation of sulphides and gold at 400-300 řC. Within the scope of this thesis the paragenesis of rock-forming minerals of granodiorite porphyry dikes hosting Au-bearing ores, as well as of late-magmatic to hydrothermal minerals filling in miarolitic cavities in these porphyries, were also interpreted. A hypothesis of granodiorite dikes' origin is suggested as well, involving mixing of magmas with different geochemical signatures.
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