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Genesis of the eruptive center of rhyolite ignimbrites, the Křivoklát-Rokycany volcanic complex
Ptáček, Jakub ; Tomek, Filip (advisor) ; Verner, Kryštof (referee)
English abstract This bachelor's thesis focuses on the tectonic and volcanological characteristics of the Křivoklát-Rokycany volcanic complex in the Teplá-Barrandian unit. The literature research part emphasizes the broader geological context, where I describe the Neoproterozoic, Cambrian, and lower Ordovician geotectonic development of the Teplá-Barrandian unit within the Avalonian-Cadomian orogenic belt. In the Křivoklát-Rokycany volcanic complex, I focus in detail on the relatively youngest part, which consists of the entire spectrum of facies of rhyolite composition and includes coherent lavas, tuffs, ignimbrites, and dike equivalents. The field research of the practical part of the bachelor's thesis took place in a satellite body of porphyritic rhyolite in the Těškov quarry, about 10 km northeast of Rokycany. The aim of the detailed geological mapping of the investigated quarry was the petrographic description of four distinct rhyolite facies, mapping of their spatial distribution, and possible determination of the eruptive center. Other research methods included analyzes of in-situ magnetic susceptibility and size distribution of rhyolite breccia clasts. The result of the work is a three- dimensional model of the quarry with detailed distribution of rhyolite facies. From the obtained data, I assume...
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From deposition to caldera resurgence: pyroclastic density current dynamics as revealed by magnetic anisotropy of the Teplice rhyolite, Bohemian Massif
Vitouš, Petr ; Tomek, Filip (advisor) ; Mlčoch, Bedřich (referee)
Better understanding of pyroclastic density current (PDC) dynamics is one of the key volcanological focuses, as PDCs represent one of the most life-threatening volcanic hazards. PDCs associated with explosive collapse calderas are difficult to observe and examine directly, and thus research of internal architecture of calderas and their PDC deposits is focused on extinct and partly eroded volcano-plutonic systems. Such a case is the Late-Carboniferous Altenberg-Teplice caldera in NW Bohemian Massif, which exposes a large body of ignimbrites (deposits of the PDC) called Teplice rhyolite (an intra-caldera fill). This body is well exposed on the southern flank of the Krušné hory/Erzgebirge Mts., mainly its members: Teichweg, Lugstein-Pramenáč, Vlčí kámen-Medvědí vrch and Přední Cínovec. As these ignimbrites appear macroscopically isotropic, I employed the Anisotropy of magnetic susceptibility (AMS) in order to quantify their internal structure. A total of 1232 specimens from 63 sampling stations were analyzed for the AMS, complemented by susceptibility vs. temperature variations and petrographic observations. Obtained AMS data, carried by a mixture of paramagnetic ferrosilicates and low-Ti titanomagnetite, indicate various processes recorded in ignimbrites. The relatively oldest and moderately welded Teichweg...
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From deposition to caldera resurgence: pyroclastic density current dynamics as revealed by magnetic anisotropy of the Teplice rhyolite, Bohemian Massif
Vitouš, Petr ; Tomek, Filip (advisor) ; Mlčoch, Bedřich (referee)
Better understanding of pyroclastic density current (PDC) dynamics is one of the key volcanological focuses, as PDCs represent one of the most life-threatening volcanic hazards. PDCs associated with explosive collapse calderas are difficult to observe and examine directly, and thus research of internal architecture of calderas and their PDC deposits is focused on extinct and partly eroded volcano-plutonic systems. Such a case is the Late-Carboniferous Altenberg-Teplice caldera in NW Bohemian Massif, which exposes a large body of ignimbrites (deposits of the PDC) called Teplice rhyolite (an intra-caldera fill). This body is well exposed on the southern flank of the Krušné hory/Erzgebirge Mts., mainly its members: Teichweg, Lugstein-Pramenáč, Vlčí kámen-Medvědí vrch and Přední Cínovec. As these ignimbrites appear macroscopically isotropic, I employed the Anisotropy of magnetic susceptibility (AMS) in order to quantify their internal structure. A total of 1232 specimens from 63 sampling stations were analyzed for the AMS, complemented by susceptibility vs. temperature variations and petrographic observations. Obtained AMS data, carried by a mixture of paramagnetic ferrosilicates and low-Ti titanomagnetite, indicate various processes recorded in ignimbrites. The relatively oldest and moderately welded Teichweg...
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