|
|
Genetic relationships between intrusions of porphyry dykes and formation of Au ores at Petrov and Bohuliby
Petrov, Ivan ; Zachariáš, Jiří (advisor) ; Slobodník, Marek (referee)
This master's thesis is focused on genetic relationships between Au-bearing ores and associated granodiorite porphyry dykes in Petrov and Bohuliby area in southwestern part of the Jílové ore district. Subvolcanic rocks with hydrothermally induced alteration and Au/bearing mineralization were characterized by petrography, mineralogy and crystallochemistry. Mutual genetic and textural relationships of studied materials were examined as well and were validated by biotite, arsenopyrite and chlorite empirical geothermometry. First identified generation of sulfide mineralization was formed at 360řC and consist of arsenopyrite, galenite and native gold. At circa 274řC porphyry mineral association was chloritized, and chlorite gangue crystallized. Second generation of sulfide mineralization precipitated at 264řC. Anomalous absence of Bi-Te-S phases and scheelite in hydrothermal paragenesis is important indicator of contrasting conditions of mineralization at the studied areas and main zone of the Jílové ore deposit. Based on acquired data, granodiorite porphyry dikes were categorized to two separate genetic types, which have mutual origin in deep magma chamber of Central Bohemian Plutonic Complex but intruded non-contemporaneously.
|
|
|
Genetic relationships between intrusions of porphyry dykes and formation of Au ores at Petrov and Bohuliby
Petrov, Ivan ; Zachariáš, Jiří (advisor) ; Slobodník, Marek (referee)
This master's thesis is focused on genetic relationships between Au-bearing ores and associated granodiorite porphyry dykes in Petrov and Bohuliby area in southwestern part of the Jílové ore district. Subvolcanic rocks with hydrothermally induced alteration and Au/bearing mineralization were characterized by petrography, mineralogy and crystallochemistry. Mutual genetic and textural relationships of studied materials were examined as well and were validated by biotite, arsenopyrite and chlorite empirical geothermometry. First identified generation of sulfide mineralization was formed at 360řC and consist of arsenopyrite, galenite and native gold. At circa 274řC porphyry mineral association was chloritized, and chlorite gangue crystallized. Second generation of sulfide mineralization precipitated at 264řC. Based on acquired data, granodiorite porphyry dikes were categorized to two separate genetic types, which have mutual origin in deep magma chamber of Central Bohemian Plutonic Complex but intruded non-contemporaneously.
|
|
|
Problems of definition and classification of lamprophyres
Kubínová, Šárka ; Holub, František (advisor) ; Štemprok, Miroslav (referee)
Lamprophyres are mafit to ultramafic porphyritic rocks containing phenocrysts of hydrated mafic minerals, namely dark mica (phlogopite, biotite) and amphibole that are present also in the matrix and commonly are euhedral or nearly euhedral. On the other side, felsic minerals as various feldspars and feldspathoids, are present only in the matrix sometimes containing also significant amounts of primary carbonates. Lamprophyres are commonly divided into three major groups - (1) calc-alkaline, (2) alkaline, and (3) ultramafic. Some of them are closely related to kimberlites, lamproites and carbonatites and gradual transitions to these rocks as well as to other non-lamprophyric types do exist. Lamprophyres are volumetricaly minor group of igneous rocks.. In some respects, however, they are very important, particularly for our understanding of complicated petrogenetic processes in the upper mantle and lower crust, and also diamond or gold prospecting. Significant role in proper lamprophyres classification is played by perception of processes of lamprophyres magmas forming and their possible interaction with crustal material or enrichment by some elements contained in mantle. Lamprophyres may be very similar to normal igneous rocks. These rocks can be distinguished only on the basis of some mineralogical...
|
guest ::
