<P> The Faymar Gold Property, near Timmins Ontario, is cross-cut by two quartz-carbonate veins. Isotopic measurements of carbon species in fluid inclusions in these quartz-carbonate veins, reveal the presence of CO2 and other light carbon species (eg. CH4). The inclusion contents were liberated using thermal decrepitation. The results obtained are found to vary quite significantly with various periods and temperatures of heating. The most useful results were obtained from samples heated for 5 minutes at 550 °C. The short heating period reduces fractionation and reaction effects. Mass spectrometer measurements of the carbon isotopes reveal that the CO2 and total carbon in the inclusions are characterized by a δ13c of -3.O and -4.7 respectively. A magmatic source for the fluids most easily explains these values. Petrographic observations indicate that secondary inclusions dominate. Thus, the isotopic measurements are of fluids which post-date the deposition of the quartz-carbonate or at least represent a late stage of this process. Since the mineralization in the veins also appears to be secondary to the quartz-carbonate (ie. in fractures), it is possible that the carbon species in the inclusions are distinct of the mineralizing fluids. </p> / Thesis / Bachelor of Science (BSc)

<p> The Meguma Group is situated in the southeastern and southwestern regions of Nova Scotia. The Meguma Group is divided into two formations: the Goldenville and the Halifax. Both formations are comprised of A and E divisions of the Bouma sequence. Thus, the Meguma Group is a turbidite deposit. Auriferous quartz veins strike parallel to bedding and occur between the lower Bouma cycle's E division and the overlying Bouma cycle's A division. The development of bedding-parallel veins was due to hydraulic fracturing of the Bouma units.</p> <p> The bedding-parallel quartz veins were emplaced at low temperatures, from 260°C to 300°C. The fluid which precipitated the gold-arsenopyrite-quartz veins consisted of a divalent cation salt species (MgCl2) and hydrosulphide ligands which were the main complexing agent of gold.</p> <p> Gold was precipitated due to the reduction of sulphide ligands as they came into contact with the organic-rich slates of the E division of the Bouma sequence. Sulphide reduction was not complete, thus a large concentration of gold remained in solution later to be precipitated with arsenic in arsenopyrite.</p> / Thesis / Bachelor of Science (BSc)

The Mokrsko-West deposit, situated about 20 km south from Prague, is one of the most important gold deposits in the Bohemian Massif. We can find hydrothermal quartz veins in two types of host rocks: tonalite in the Central Bohemian Plutonic Complex (CBPC) and amphibolite in the Jílové Belt (JB). A several generations of the quartz veins with different mineralization were found in the deposit. This study has several objectives. At first, it determines and compares the chemistry of quartz samples from different generations of hydrothermal veins. In addition, this work describes the distribution of the most important trace elements. Lastly, the work compares the potential differences in the chemistry of samples from the different host rocks (CBPC and JB). With the use of the LA-ICP-MS, 16 quartz samples from the Mokrsko-West deposit were analysed. Finally, 101 analyses were realized. From the analysed trace elements, the most important were Li, Mg, Al, Ca, Fe, Cu, Zn, As, Sb and Pb. Aluminium affects the concentration of the most of analysed trace elements. Positive correlation between Al and the other metals was also found. The samples with high Al content also showed high concentrations of other metals (Fe, Cu, Zn, Pb) and As. Samples with lower Al content showed lower concentration of other metal...

Veins are ubiquitous features in deformed rocks. Despite observations on syntectonic veins spanning two centuries, fundamental questions remain unanswered. Their origin as fractures is largely established but it is still not known why these fractures initiate where they do and how the vein evolves once started. We studied veins from the Lower Ordovician Mazarn Formation in the Arkansas’ Ouachitas combining textural observations, stable isotopes, fluid inclusions, SEM-based cathodoluminescence and electron back-scattered diffraction to understand the initial stage of vein formation, its later evolution, the role of fluids and their environment of formation. The veins are located at boudin necks and are synchronous with cleavage formation. Texturally, veins are characterized by veinlets (thin veins between 5 and 25 μm thick) that parallel the vein-host interface and fibers (columns of quartz or calcite) perpendicular to the vein-host interface between 30 and 350 μm wide. Veinlets are localized fractures filled with quartz. The crystallographic orientation of the precipitated material in veinlets is inherited from host grains at the micron scale and replicated as fibers’ lengths grow to centimeters. The vein-forming fluid was cyclically supersaturated yet never very far from saturation. δ18O values of vein quartz and host are within 2‰ of each other suggesting that the fluid was rock-buffered. Nevertheless, δ18O and δ13C define a ‘J’ shaped trend. Although it is not possible to date any portion of this curve, the simplest explanation is that the fluid evolved from rock-buffered in a closed system to fluid-dominated in an open system. The range of pressure-temperature conditions of vein formation is between 275 and 385 °C and 1100 and 3400 bars, from fluid inclusions and quartz-calcite oxygen isotopes thermometry. By examining a vein from tip to middle, we have established a sequence of events from inception to maturity in vein growth. Vein formation starts with folding followed by flattening of resistant sandstone layers which in turn gives rise to boudinage. Boudinage formation allowed for fracture localization along boudin-necks. The vein grew by the repeated addition of veinlets in the neck region. Recrystallization later modified the fibers by obliterating some evidence of the veinlets and moving fiber walls.

Veins are ubiquitous features in deformed rocks. Despite observations on syntectonic veins spanning two centuries, fundamental questions remain unanswered. Their origin as fractures is largely established but it is still not known why these fractures initiate where they do and how the vein evolves once started. We studied veins from the Lower Ordovician Mazarn Formation in the Arkansas’ Ouachitas combining textural observations, stable isotopes, fluid inclusions, SEM-based cathodoluminescence and electron back-scattered diffraction to understand the initial stage of vein formation, its later evolution, the role of fluids and their environment of formation. The veins are located at boudin necks and are synchronous with cleavage formation. Texturally, veins are characterized by veinlets (thin veins between 5 and 25 μm thick) that parallel the vein-host interface and fibers (columns of quartz or calcite) perpendicular to the vein-host interface between 30 and 350 μm wide. Veinlets are localized fractures filled with quartz. The crystallographic orientation of the precipitated material in veinlets is inherited from host grains at the micron scale and replicated as fibers’ lengths grow to centimeters. The vein-forming fluid was cyclically supersaturated yet never very far from saturation. δ18O values of vein quartz and host are within 2‰ of each other suggesting that the fluid was rock-buffered. Nevertheless, δ18O and δ13C define a ‘J’ shaped trend. Although it is not possible to date any portion of this curve, the simplest explanation is that the fluid evolved from rock-buffered in a closed system to fluid-dominated in an open system. The range of pressure-temperature conditions of vein formation is between 275 and 385 °C and 1100 and 3400 bars, from fluid inclusions and quartz-calcite oxygen isotopes thermometry. By examining a vein from tip to middle, we have established a sequence of events from inception to maturity in vein growth. Vein formation starts with folding followed by flattening of resistant sandstone layers which in turn gives rise to boudinage. Boudinage formation allowed for fracture localization along boudin-necks. The vein grew by the repeated addition of veinlets in the neck region. Recrystallization later modified the fibers by obliterating some evidence of the veinlets and moving fiber walls.

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Locality Mokrsko-west is located inside the Josef mining gallery and belongs to the ore district Psí Hory Mountains, known for its high content of micro-granular gold (~ 100 g/t). It is situated within the apophysis of Sázava tonalite, which is a part of Central Bohemian Plutonic Complex, located southerly from Prague. Besides other structural elements, the whole locality contains the network of sheeted quartz veinlets, which is the aim of this thesis. Data from vectorization and image analysis of the photographic documentation from the gallery and electron microscope has been used. The statistical approach has been used to quantify proportions of mineral phases within the quartz veinlets, their cumulative spacing and fractal distribution. Image analysis confirmed the presence of K-feldspathic metasomatism which affects the plagioclase grains. It forms rims on the edges of the quartz veinlets. The proportional relationship of K-feldspar and quartz within the veinlets wasn't confirmed. It's therefore possible that they were two separate processes of the uncertain time relation. Transfer from the lognormal distribution in histograms of vein spacing in drill-cores to the more normal distribution of the veinlets in the gallery walls was observed. Results from the cumulative spacing analysis confirmed...

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