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Geochemistry and petrology of plagiogranites from the Jílové belt
Santolík, Václav ; Ackerman, Lukáš (advisor) ; Jelínek, Emil (referee)
This thesis is focused on the study of the subvolcanic rocks from the northern part of the Jílové belt. The Jílové belt is a strip of magmatic rocks belonging to the Davle Volcanic Complex situated in the center of the Bohemian Massif, south of Prague, close to the border between the Teplá-Barandian and Moldanubian units. The sub-volcanic facies of its northern part has been previously ascribed to trondhjemite, alaskite or plagiogranite. In this study, we provide new geochemical data such as major and trace element analyses paralleled by Sr-Nd isotopic data, which indicate the origin of these rocks in the mantle wedge. They probably represent a final product of a magmatic differentiation of an island arc series. Here, we consider two possible models for their origin, according to which we could also choose the correct classification of these peculiar rocks: adakite, or plagiogranite. Adakites are rocks formed by melting of a subducted slab which are predominantly related to the volcanic arc settings. In comparison, plagiogranites are rocks formed by an extreme differentiation of a mantle- derived basaltic melt in the oceanic crust environment. Our new geochemical data, especially the low degree of light rare earth enrichment (LaN/YbN = 0.8-1.3), is clearly inconsistent with the genetic association...
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Silurian and Devonian volcanism of the Prague Basin
Tasáryová, Zuzana ; Frýda, Jiří (advisor) ; Renno, Axel D. (referee) ; Awdankiewicz, Marek (referee)
The principal goal of the thesis is to constrain nature of magmatic and alteration processes, character of mantle source(s), geotectonic setting and palaeogeographic implications of the Silurian and Devonian volcanism in Prague Basin (Teplá-Barrandian Unit, Bohemian Massif). The thesis is based on extensive geochemical study covering major- and trace-element geochemistry, neodymium isotope geochemistry and mineral chemistry supported by petrographic and field observations. The most important conclusions of the thesis are as follows: 1. The Silurian volcanic rocks of the Prague Basin represent within-plate, transitional alkali to tholeiitic basalts, which erupted in continental rift setting through thick Cadomian crust. The basalts originated by low degrees of partial melting of garnet peridotite mantle source. Older Wenlock basalts are similar to alkaline ocean island basalts (OIB) derived from subcontinental lithospheric mantle (SCLM), enriched most probably by frozen pods of Ordovician magmas. Younger Ludlow basalts resemble tholeiitic enriched mid-oceanic ridge basalts (EMORB) derived from subduction-modified SCLM depleted by Late Cambrian melting. The Wenlock-Ludlow melting is characterized by contemporaneous mixing of melts derived from both enriched and depleted SCLM mantle domains. 2....
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The Origin of Compositional and Textural Zoning of Shallow-Level Granitoid Plutons
Trubač, Jakub ; Janoušek, Vojtěch (advisor) ; Broska, Igor (referee) ; Siebel, Wolfgang (referee)
The principal goal of this Ph.D. Thesis is to contribute to the research on formation of compo- sitional and textural zoning in shallow-level plutons. Processes responsible for emplacement of individual plutons/pulses and the origin of compositional zoning in are addressed in a great detail, from the pluton-scale down to the micro-scale. The main emphasis in the more focused part of this text is on a combination of various quanti- tative data sets from two well-selected plutons (the Říčany Pluton in the Central Bohemian Plu- tonic Complex and the Melechov Pluton in the Moldanubian Batholith). These detailed studies are supported by further research on the Štěnovice, Čistá and Ševětín plutons. In this way we cover the evolution of Variscan magmatism in the heart of Bohemian Massif in its entirety, from Late Devonian till Permian. The thesis is based on combining field and structural studies (including the anisotropy of mag- netic susceptibility, AMS), textural analysis, petrological, geochronological and geochemical methods with geophysical investigations. Mathematical approaches have been designed and applied to the interpretation of geochemical data, with potential applications to other igneous systems. I strongly believe that only such comprehensive studies on well-selected case examples have a...
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Neovolcanic Rocks of the SW part of the Most Basin in the area of Tušimice power plant open pit
Sobotka, Martin ; Kachlík, Václav (advisor) ; Novotný, Tomáš (referee)
Diploma thesis deals with geological, petrological and geochemical studies of neovolcanic rocks of the SW part of the Most Basin in the area of Tušimice power plant open pit. There are two lava flows affected by coal mining in northern part of the mine. Petrological and geochemical studies with K-Ar dating relatively recent rocks in mostly weatherworn volcanic rocks showed, that they can be classified as Ti-rich basaltic rocks without olivine (tephrites), which belong to the main volcanic phase in the evolution of the Eger graben. It was evidenced geologicaly and with K-Ar dating, that studied rocks were seperated from underlying beda by hiatus which caused erosion of volcanic rocks as well as crystalline bedrock. Mmajor and trace elements composition of co-magmactic volcanics showed that rock were derived from two slightly different sources of upper mantle. Composition of two samples indicates the formation from low degree of partial melting strongly metasomatic asthenospheric mantle. Chemical features of volcanic rocks show that mantle source was comparamble to recent OIB basalts. Last sample arose from less metasomatized and depth distincted mantle which was affected by higher level of partial melting. Melts from which crystallized both rocks were minimaly affected by asimilation or...
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Gold-bearing quartz veins in peripheral parts of the Jílové ore district and their comparison with the orogenic gold type of mineralization
Žitný, Tomáš ; Zachariáš, Jiří (advisor) ; Strnad, Ladislav (referee)
This thesis discusses gold deposit types, reviews historical approaches to their classification, and focuses in more detail on modern classification approaches. A new classification of gold deposits is presented, and the orogenic deposit type is described in detail. All important characteristics and features of this deposit type are presented. The second part of this thesis discusess the geology and mining history of Jílové u Prahy, which historically has been the most important gold-bearing district in the Czech Republic. A number of other, less important gold-bearing areas are located at periphery of this district, but these areas have yet to be geologicaly studied in detail. The Radlík and Zahořany gold-bearing areas are studied in detail in this thesis. Structural measurements in these areas are presented, some of which are from outcrops, while others come from several adits that have been preserved to the present day. Geological maps of parts of some these adits are presented, focusing on those that could be useful for deposit type identification. The thesis goes on to discuss gangue samples, which were studied microscopically, with fluid inclusions in quartz also subjected to study. The final part of the thesis presents a comparison between the orogenic gold deposit type and measured data. However,...
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Trace element and Re-Os geochemistry of mantle pyroxenites from the Bohemian Massif
Haluzová, Eva ; Ackerman, Lukáš (advisor) ; Jelínek, Emil (referee)
Mantle pyroxenites are important components of mantle rocks, because they provide important insights into bulk composition and heterogeneity of the Earth's upper mantle and therefore, direct evidence of mantle evolution throughout the Earth history. Studied pyroxenites from localities Bečváry (the Kutná Hora Complex), Níhov, Nové Dvory, Mohelno, Horní Kounice, Karlstteten and Meidling (the Gföhl Unit of the Moldanubian Zone) occur as dykes and/or layers within spinel and garnet peridotites from the Bohemian massif. Whole-rock concentrations of rare earth (REE) and other trace elements in studied pyroxenites yield extreme variability, which most likely reflect: 1) variable garnet/clinopyroxene ratios in bulk rocks, 2) different degree of fractionation of parental melts and 3) different concentrations trace elements in the source host material. Pyroxenites from locality Mohelno (LREE-depleted) may be derived from depleted or only slightly enriched suboceanic mantle. In contrast, pyroxenites from Karlstetten, Meidling, Horní Kounice and Nové Dvory (LREE-enriched) crystallized from the melts derived from enriched mantle source with possibly significant contribution of recycled crust. Studied pyroxenites are characterized by extremely variable 187 Os/188 Os ratios. While the pyroxenites from Mohelno and...
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Volcanics of the southeastern flank of the barrandian Neoproterozoic in vicinity of Dobříš
Mráček, Michal ; Kachlík, Václav (advisor) ; Stárková, Marcela (referee)
Diploma thesis deals with geological, petrological, structural and geochemical studies of the most probably neoproterozoic volcanic and sedimentary rocks of the Pičín belt in the area NW from Dobříš, approximately between the villages Trnová and Chouzavá. Volcanics of Kozí hory area, which are demonstrably included into Davle Formation have beeen used for comparison with the Dobříš area. One of the major part of the work includes geological mapping on scale of 1:10 000, which served as a base for a more detailed petrological, structural and geochemical studies. Some lenses of lava and volcanoclastic breccia and minor layer spilite were newly discovered, areal extent of some cherts bodies and basaltic dykes were modified. Basalts, andesites and dacites bodies have been reclassified against the basic geological map of 1:25 000 (Havlíček, 1985; Mašek, 1987). Basalts in the Havlíček's (1985) map actually represent a very fine-grained rhyolites (ignimbrites) with disseminated ore minerals with layers of pyroclastic rocks (ignimbrites, volcanoclastic breccia). Areal extent of andesites and dacites bodies were modified and new body of trachyandesite was detected. Extremely fast cooled grained textures and series of features corresponding to welded tuff (ignimbrites) shows that the tuffs were deposited in...
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The origin of podzols and distribution of elements induced by podzolization.
Pánik, Róbert ; Mihaljevič, Martin (advisor) ; Borůvka, Luboš (referee)
Part I. The purpose of this work is to review publications and present a novel approach to the interpretation of available data in attempt to explain process of podzolization. First, we consider all major inputs that affect podzol formation from global to microscopic scale - climate, parent material, vegetation, mycorrhizal fungi, and fire regime in the podzol areas. Important role of fire-produced charcoal in the podzolization process due to its specific properties is also considered. Subsequently, physico-chemical transitions upon the downward progression of podzolization front (i.e., C to Bs, Bs to Bhs, and Bhs to E) are treated, in conjunction with the characterization of secondary phases that precipitate in the Bs horizon, as well as the demonstration of the major role of organic matter in the formation of podzols. Organic carriers exuded by plants and fungi are shown both to decrease mobility of certain elements (e. g., Ca, Al) by the formation of secondary solid phases, and also to increase mobility of otherwise unavailable elements (e.g., Fe) by their chelating abilities. Special emphasis is given to siderophores, group of organic substances that show high and specific affinity for Fe3+ chelation over a wide range of pH. Finally, spatial and temporal trends of podzolization and podzol...
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Comparisoon of leucogranitoids from divergent and convergent tectonic settings
Janoušková, Renata ; Kachlík, Václav (advisor) ; Trubač, Jakub (referee)
Granitoid belong to one of the most important rock type in the continental crust, especially in the orogenic belts. We classify them into several basic types, accrording to their mineral composition, petrographic and petrogenetic features, chemical composition and geotectonic environment of their origin. Genetically very interesting type of granitoids, genesis of which is widely discussed in the present literature, are leucogranitoids. They represent, with exception of very old Archaic granitois of tonalite-trondhjemite-granodiorite suite products of extreme differenciation of magmas, which are derived from various crustal and mantle souces, or originate by magma mixing and mingling processes and by reaction of melts with country rocks during magma ascent. According to geotectonic setting of their origin, leucogranitoids can be divided into leucogranitoids, which originate on divergent plate margin, especially on the mid-ocean ridges and in the leucogranitoid, which originate on destructive plate margins - island arcs or active continental margins. The submited work presents petrographic and geochemical characteristic of individual leucogranitoids types, characterizes sources of magmas, tectonic setting and major differentiation processes as partial melting of water and fluids saturated rocks,...
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