Mechanisms of Post-Hydrothermal Deformation in Orogenic Gold Deposits : A Case Study of the Klondike Gold District, Yukon

The Klondike Gold District (KGD) is situated in west-central Yukon, located on the pericratonic Yukon-Tanana Terrane. The region is a major producer of placer gold, famous for the Gold Rush of 1896, and has produced an estimated 10 Moz. of gold (Chapman at al., 2010) derived from gold-bearing quartz veins and greenschist Klondike Schist host rocks. This research investigates the structural controls on mineralization of the Lone Star Ridge area, providing new field observations and interpretations of the sequence of deformation events related to vein formation and gold mineralization. Overprinting relationships of ductile deformation and brittle, mineralized veins in field observations have provided evidence for deformation outlasting hydrothermal vein emplacement, contrary to the post-deformation vein emplacement hypothesis outlined in recently published literature. Detailed petrographic investigations and cathodoluminescence imaging of quartz veins and altered wall rock indicate that post-hydrothermal vein deformation has occurred and that strain partitioning may have played a role in enhancing gold grades. The evidence for post-hydrothermal vein emplacement has broad implications for the deformational history of the KGD, concluding that ductile deformation related to regional thrusting was ongoing though hydrothermal vein emplacement. Historical exploration has focused on discovering lode gold associated with primary hydrothermal veins, whereas the overprinting deformation affecting these veins may have potentially remobilized gold to later precipitate into structures controlled by the overprinting deformation.Science, Faculty ofEarth, Ocean and Atmospheric Sciences, Department ofUnreviewedUndergraduat