1. Gold mineralization in the Archean Wawa Gold Corridor, Wawa, Ontario
- Author
-
Wehrle, Elliot Andrew
- Subjects
Pyrite ,LMCE polymetallic melts ,Gold ,Arsenopyrite ,LA-ICP-MS - Abstract
The Wawa Gold Corridor (WGC), located in the Michipicoten greenstone belt, comprises Au-bearing shear zones that crosscut the 2.75 Ga Jubilee Stock. Shear zones formed during protracted deformation (D1 – D3) and contain Au mineralization produced by two major events. The first comprises syn-deformation gold with arsenopyrite and pyrite in D1 – D2 schists and the second comprises post-deformation gold with Bi-Te minerals, chalcopyrite, and pyrite in carbonate ± riebeckite alteration rims around pyrite in D3 shear veins. Observations of porosity and inclusions in D1 arsenopyrite and D2 pyrite suggest that these sulfides underwent coupled dissolution-precipitation reactions (CDR). Based on trace-element analysis by laser-ablation inductively-coupled plasma mass spectrometry, it is evident that the replacement of Au-rich minerals by Au-poor minerals during CDR generated native gold from Au previously in solid-solution. Textural relationships amongst gold and Bi-Te minerals are consistent with precipitation from a Bi-rich polymetallic melt during the second gold event. The rare presence of riebeckite in the siderite-rich coronae that host Au-Bi-Te assemblages suggests that this event was associated with the emplacement of 1.0 Ga lamprophyre dikes. However, overlap in the δ34S values of pyrite in this event (0.4 – 2.4 ‰) with those of earlier pyrite (0.1 – 4.1 ‰) indicate recycling of pre-existing sulfide sulfur during the 1.0 Ga hydrothermal overprint. By comparing the Au contents of arsenopyrite (10s – 1,000s of ppm) to those of pyrite (
- Published
- 2020