Lisa MacDonald
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B. Sc. Honours Thesis
Carbonate in the Oldham Gold Deposit, Nova Scotia
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Metaturbidite-hosted gold deposits share many common characteristics, including enrichment in carbonate minerals. Gold deposits within the Meguma Group also share some of these features, including the Oldham gold deposit. Regional mapping showed high levels of carbonate within the deposit as well as enrichment in arsenopyrite and the presence of an unusual biotite-rich, mineral aggregate. Regional sampling both inside and outside the deposit occurred as well as sampling of drill core in an attempt to gauge the size of the enrichment and in order to characterize its nature.
CO2 analyses yielded preferential enrichment of carbonate in metasandstones within the deposit, particularly within a drill core section immediately adjacent to a quartz vein.
Petrographic study of the samples, both regional and core, uncovered the presence of four types of carbonate; carbonate veinlets, carbonate in quartz veins, carbonate porphyroblast and matrix carbonate. Textural analysis relatively dates the carbonate as late-stage with respect to metamorphism.
The similarities of a variety of features such as depletion in SiO2 and As abundance found within the Oldham deposit with features in deposits with known alteration, suggests the possibility that hydrothermal alteration may be responsible for the anomalies recorded in the Oldham deposit. Whole rock and mineral chemistry data from CO2 analysis, X-ray fluorescence analysis and microprobe analysis on samples from the deposit yielded no conclusive evidence for hydrothermal alteration.
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Supervisors: Gunter Muecke and Rick Horne