Masters Degrees (Earth Sciences)

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Browsing Masters Degrees (Earth Sciences) by Author "Comuso, Christina Marie"

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    Fluid inclusion and δ18O isotope values of fluids responsible for mineralization in the Hope Reef and Main Reef Complex of the Fairview Mine, Barberton, South Africa
    (Stellenbosch : Stellenbosch University, 2020-03) Comuso, Christina Marie; Von der Heyden, Bjorn; Stellenbosch University. Faculty of Science. Dept. of Earth Sciences.
    ENGLISH ABSTRACT: Gold mineralization within the Fairview Mine of the Barberton Greenstone Belt (BGB) is structurally confined to various mineralized shear zones, better known as reef complexes. Regionally altered lithologic units and structural features promoted large scale fluid migration that in turn resulted in the gold abundance throughout the Fairview Mine. Four progressive deformational phases along with a F3 folding event of the Ulundi syncline offer the ideal conditions for orogenic gold formation. Grades of mineralization in the HR and MRC are likely due to variations in proximal lithological packages and structural fabrics. Progressive gold rich fluid flow throughout the MRC and HR has led to the high gold endowment in both the reef complexes. This study focuses on the structurally, lithologically, and temporally different Main Reef Complex (MRC) and the Hope Reef (HR), in order to develop an understanding of the mineralizing fluids that were present throughout both reef complexes. Oriented quartz veins associated with mineralization were analyzed from both the MRC and HR for: (1) oxygen stable isotope values; (2)fluid inclusion types and trapping conditions determined by microthermometry experiments;(3)followed by a constituent analysis of volatiles within fluid inclusions through Raman microspectroscopy. The perplexities on the composition and origin of the gold mineralizing fluid, as well as the variations in alteration within the MRC and HR, will hopefully be better understood with the data presented in this study. Fluid inclusion data of secondary and primary inclusions from the HR present homogenization ranges from 185°C to 340°C. Salinity values for these analyzed FI in HR occur at 2.07 to 18.63 wt. %. Moderate clathrate melting temperatures of HR fluid inclusions, 7.90°C to 19.5°C suggest the presence of a thin liquid or vapor film of a more complex volatile, i.e. CH4, C, HCl, and N2. Like the HR data of both secondary and primary, FI from the MRC show homogenization ranges from 225.60°C to 400°C. These moderate higher homogenization values are representative of H20-CO2 rich hydrothermal fluids. The MRC displays low to moderate salinity’s ranging from 2.76 to 16.34 wt. %. Overall clathrate values for the MRC were slightly lower than HR, 1.20°C to18.9°C. Oxygen stable isotope values of selected quartz vein samples at the HR range 12.85 to 14.30‰, similarly, the MRC 13.75 to 14.90‰. Raman spectroscopy was performed on FI within both the HR and MRC revealing peaks of CO2, CH4, H2O and C. Higher intensities of CH4 are visible in the MRC then the HR. Aside from partially dissecting the fluid geochemistry of the MRC and HR, a chapter of this thesis was dedicated to documenting the technique development for the newly established fluid inclusion laboratory in the Department of Earth Science at Stellenbosch University. This brief but concise laboratory manual provides a walkthrough on how to set up and run microthermometry experiments using the Linkam THMS600 heating homogenization and freezing stage, as well as a simple yet informative methodology on how to carry out a fluid inclusion study at Stellenbosch University.