STRUCTURALLY CONTROLLED GOLD: COMPARING AND CONTRASTING 0.4 GA CENTRAL NEWFOUNDLAND AND 2.7 GA ABITIBI GREENSTONE BELT

Archean gold deposits of the Abitibi granite-greenstone terrane comprise one of the most prolific structurally controlled gold systems in the world. Gold-bearing vein systems in the Abitibi occur within and in proximity to long-lived crustal-scale fault zones characterized by footwall sequences of synorogenic clastic rocks and associated alkaline magmatism.

In the Paleozoic terrane of central Newfoundland, gold mineralization is also associated with crustal-scale fault zones that preserve synorogenic clastic rocks. The structurally controlled gold-bearing corridor in central Newfoundland occurs over a horizontal distance comparable to the Abitibi, as it trends northeast from Cape Ray for ~400 km to Fogo Island. The largest known gold deposit in Newfoundland occurs along this structurally controlled belt at Marathon Gold Corporation’s Valentine Lake Gold property, which now reports 4.2 Moz of total gold resource. Recent soil sampling programs and exploratory drilling on industry land packages adjacent to Valentine Lake confirm additional gold endowment and a clear potential for more structurally controlled resources northeast along strike. Structural analysis of recently discovered gold-bearing quartz veins along this trend demonstrates that mineralization occurs within an oblique, compressional, left-lateral shear zone, similar to deposits farther southwest at Valentine Lake.

Comparing and contrasting the structural and tectonic evolution of the major gold producing fault zones in central Newfoundland and the Abitibi is useful for identifying recurring processes related to structurally controlled gold mineralization, across >2 billion years of Earth history. Similarities in present-day fault geometries suggest that mineralized systems in both the Abitibi and central Newfoundland experienced comparable thick-skinned thrust tectonics critical to preservation of upper crustal gold deposits. An important outstanding question is whether the gold-bearing fault zones in central Newfoundland were initiated during an earlier phase of crustal-scale extensional tectonics, as is inferred for the Abitibi system. This is a key question for interpreting the primary source(s) of gold-bearing fluids in central Newfoundland.