The relationship between visible gold and arsenopyrite at the Orenada Zone 4 deposit, Val d'Or, Quebec
Abstract
The Orenada Zone 4 deposit is an Archean orogenic gold deposit situated southeast of Val d’Or, Québec in the southeastern Abitibi Greenstone Belt. It is located directly within the Cadillac-Larder-Lake Deformation Zone. Mineralization is hosted within a volcanoclastic horizon of the Cadillac Group where two distinct facies were defined. Both facies underwent a pervasive sericite-chlorite-carbonate±albite alteration assemblage that predates gold mineralization. Gold is associated with two generation of auriferous quartz-carbonate-tourmaline veins and within fractures of corroded arsenopyrite grains, located proximal to the vein walls. A LA-ICP-MS study determined that neither textural type of arsenopyrite displayed refractory gold. Therefore, gold was not remobilized from arsenopyrite but instead, likely precipitated during formation of the quartz-carbonate veins. Gold precipitation is likely related to electrochemistry gold deportment where As-rich fractures within the corroded arsenopyrite acted as p-type conductors which attract the gold particles for precipitation.