Granitoid-hosted, orogenic gold mineralization: Genetic constraints on the world-class Archean Gruyere gold deposit, Yilgarn Craton, Western Australia

In 2013, the 6.8 Moz Gruyere gold deposit was discovered at the eastern margin of the Yilgarn Craton in Western Australia. Gold mineralization at Gruyere is hosted by the 2830 +/- 4 Ma Gruyere monzogranite. Mineralizationis related to contemporaneous chlorite-rich veinlets and sheeted quartz veins crosscutting the foliation, with pervasive wall rock alteration characterized by quartz-sericite-albite-calcite-chlorite +/- pyritepyrrhotite-arsenopyrite -gold-telluride assemblages. Chlorite and arsenopyrite geothermometry indicate temperatures between 304-365 degrees Cand 360-425 degrees C, respectively. Arsenopyrite Re-Os geochronology yield a single-analysis model age of 2675 +/- 66 Ma. On the basis of these results, gold mineralization at Gruyere is interpreted to reflect a late-Archean, granitoid-hosted, orogenic gold mineral system, with the granitic intrusion behaving as a brittle, rigid body within more ductile, soft supracrustal rocks during mineralization. This implies that the 2675-2630 Ma orogenic gold mineralization event in the Yilgarn Craton was widespread and extends into the easternmost exposed part of the craton.