Gold mineralisation and mineral exploration within the Clogau mine, Dolgellau gold belt, N Wales

  • Rebecca Kelliher

    Student thesis: Master's Thesis


    Gold lodes within the Dolgellau gold belt are interpreted as emplaced by hydrothermal fluids derived from a metamorphic source creating the basement to the Cambrian succession. Previous mining in Clogau/St David’s has focused on extracting gold from the quartz veins, with gold assay results from core returning grades of up to 2.15 Au g/t. Incremental fracture reactivation is believed to accompany mineralisation with gold localization partially controlled by fracture-hosted pathways. Research in this study found gold grades, a measure of the abundance of gold ore, within borehole GMOW_LL001 in 36 places, with the most significant results being 0.81 Au g/t, 1.7 Au g/t and 2.15 Au g/t. Geochemical results where these gold grades were highest showed an increase in certain geochemical elements such as aluminium, copper, iron and sulphur. Using XRF elemental data, a partial correlation between an increase in sulphur (a geochemical proxy) against gold assay results was found indicating deposition within an anoxic and sulfidic (euxinic) environment. Geochemical data also allowed an economic basement to be located at 165.26 m where there were both changes in the bedding and laminated beds as well as a disappearance in elements associated with gold mineralisation. Gold mineralisation in borehole GMOW_LL001 was not found along microfractures and microshears but rather within the quartz veins themselves.
    Date of Award2023
    Original languageEnglish
    SupervisorDuncan Pirrie (Supervisor) & Ian Skilling (Supervisor)

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