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Paleofluid chemistry of orogenic gold deposits: novel analytical methods and case studies from the Bohemian Massif
Hrstka, Tomáš ; Zachariáš, Jiří (advisor) ; Koděra, Peter (referee) ; van den Kerkhof, Alfons (referee)
PALEOFLUID CHEMISTRY OF OROGENIC GOLD DEPOSITS: NOVEL ANALYTICAL METHODS AND CASE STUDIES FROM THE BOHEMIAN MASSIF Tomáš Hrstka1 1 Charles University in Prague, Faculty of Science, Institute of Geochemistry, Mineralogy and Mineral Resources, Albertov 6, Praha 2, CZ-128 43 Abstract of the Ph.D. Thesis Fluid inclusions represent a unique tool for understanding the processes leading to the formation of mineral deposits and fluid-rock interactions in general. Orogenic gold deposits in the central part of the Bohemian Massif (Libčice and Kasejovice deposits) were studied in order to provide a better understanding of their genesis. A multifaceted approach was adopted including a broad spectrum of micro-analytical methods. While traditional methods were used as the basis of this study (e.g., microthermometry, SEM and optical microscopy), the application and improvement/development of modern analytical methods (e.g., LA-ICP- MS and Raman spectroscopy) or introduction of alternative innovative techniques (CLSM, Nano- tomography, QEMSCAN) constituted a significant part of this study. This study reveals the importance of the HCO3 - species in hydrothermal fluids (i.e., >100 řC to ~350 řC). Previously, the prevalence of Cl- and other anions was reported for hydrothermal paleofluids and the majority of studies suggested...
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Historical cinnabar deposits in Bohemia - genetic study.
Velebil, Dalibor ; Ackerman, Lukáš (referee) ; Zachariáš, Jiří (advisor)
The study of fluid inclusions proved the metamorphic origin of the cinnabar-pyrite mineralization at the deposit of Horní Luby. In addition, thermal conditions of the mineralization formation were determined. During the deposit forming processes, the primary homogenous H2O-CO2 fluid of the temperature of about 300řC was differentiated to fractions rich in H2O or CO2. The differentiation took place in several stages in the temperature range between 200 to 150řC. Quartz crystallized from the parent fluid at the temperature about 300řC, pyrite at temperatures in the range of 220řC to 210řC and cinnabar at temperatures in the range of 195řC to 160řC. The cinnabar is thus the youngest mineral at the deposit (crystallization succession. quartz - pyrite - cinnabar). At the deposit of Jedová hora, quartz crystallized at the temperature of about 160řC to 150řC, barite at temperature of about 115řC (the fluid boiling point) and cinnabar in the range between these temperatures. The origin of mercury at all Czech historical deposit of cinnabar can be very likely related to Lower Paleozoic submarine volcanism. In all cases, the pre-concentrated mercury was remobilized during the Variscian metamorphosis, followed by precipitation in form of veins with cinnabar or as cinnabar impregnation. Study of tetrahedrite...
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