Abstract The Archean Goldex deposit, located in the Val-d’Or gold camp in the southern Abitibi greenstone belt, Canada, comprises two contrasting styles of gold mineralization that result from two distinct ore-forming events that happened ≥25 m.y. apart. The first is an early (pre-2685 Ma), pre-D3 event forming the volcanic-hosted South Zones vein system in the immediate structural footwall (south side) of the Goldex quartz diorite. The second is a late, ca. 2660 to 2640 Ma syn-D3 event forming an orogenic vein system within the 2686.3 ± 1.2 Ma quartz diorite. The South Zones consist of deformed smoky quartz veins and diffuse domains of intense silicification with variable amounts of disseminated pyrrhotite-pyrite ± sphalerite-chalcopyrite native gold, bordered by a metamorphosed assemblage of pervasive biotite-quartz-pyrrhotite ± amphibole-epidote alteration. Many characteristics of the South Zones, such as folding, boudinage, and dynamic recrystallization, indicate that they predate the main phase of regional deformation (D3) shortening and peak metamorphism. In contrast, the bulk of the Goldex deposit consists of a network of steeply and shallowly S-dipping quartz-tourmaline-carbonate-pyrite vein stockworks and breccias with proximal albite-pyrite alteration. The South Zones deposit is part of a group of early structurally controlled gold deposits that are spatially associated with a WNW-trending structural corridor (referred to as the Marbenite-Norbenite corridor) that originated prior to D3, which plausibly represents a significant D1 to D2 fault zone. The juxtaposition of these two temporally and geologically distinct gold deposits (i.e., pre-D3 vs. syn-D3) attests to the longevity of the Marbenite-Norbenite structural corridor and highlights the importance of early structures as gold metallotects and multiple mineralizing events in the formation of world-class gold camps in polydeformed terranes.
Maw et al. (Thu,) studied this question.