Geology, Geochemistry and Gold Mineralization in the Madrid Corridor, Hope Bay Volcanic Belt, Nunavut, Canada

Abstract

The Hope Bay Volcanic Belt (HBVB) is a north-south striking mafic volcanic greenstone belt in the northeastern Slave Province. Mineralized mafic flows divide into two lithotectonic packages. Komatiitic basalts exhibit elevated Fe-Ti-Cr-Ni, incompatible element enrichment and a within-plate basalt signature. High-Fe tholeiitic basalts have lower Fe-Ti-Cr-Ni values and a primitive tholeiitic island arc signature. Together, these two packages represent a plume influenced subduction environment. The interface between these two units was the focus of early deformation giving rise to the Hope Bay Deformation Zone (HBDZ). The HBDZ controls the distribution of gold mineralization at Madrid with all deposits occurring adjacent to the structure. An early high-temperature alteration event syn/predating the intrusion of the 2686 Ma Wolverine Porphyry is characterized by K-metasomatism, phengite formation and magnesite/ankerite blastesis. Early alteration softened the rocks, making them amenable to late D2 mineralization. This corresponds to the main Au event characterized by Na-metasomatism, paragonite growth, and Au-W enrichment.