Master of Science
Dr. G.R. Osinski, Dr. R.L. Linnen
Sudbury breccia is an impactite situated in the footwall of the 1.85 Ga Sudbury impact structure, situated in Ontario. Developing exploration vectors towards Sudbury breccia-hosted Cu-Ni-PGE mineralization is inhibited by an insufficient understanding of the relative contributions of footwall lithologies versus impact melt. By combining whole-rock geochemistry, field observations, statistical modelling and petrography, this study has determined that Sudbury breccia is a parautochthonous shock melt, which does not require a melt sheet contribution. Furthermore, the trace metal content of the breccia is largely controlled by the assimilation of mafic footwall lithologies, the exception being breccia proximal to mineralization, where a hydrothermally remobilized component is identified. Mineral chemistries demonstrate that some metal remobilization in breccia from both the North and South Range is associated with shear zones and hydrothermal-metamorphic activity. Biotites, amphiboles, chlorites and titanites have geochemical signatures consistent with increased pressure and/or temperatures conditions towards deformation structures hosting sulfide ores.
O'Callaghan, Jonathan W., "Constraining the Formation and Alteration of Sudbury Breccia, Ontario, Canada: Implications for Footwall Cu-Ni-PGE Exploration" (2016). Electronic Thesis and Dissertation Repository. 4075.