CARLIN-TYPE GOLD MINERALIZATION AT SAINT-ANDRÉ-DE-RISTIGOUCHE, GASPÉ PENINSULA (QUÉBEC), CANADIAN APPALACHIANS

Abstract

The Gaspé Peninsula, in the Canadian Appalachians, hosts a variety of mineral occurrences that are spatially associated with the Grand Pabos and Restigouche faults. Among these occurrences, the Saint-André-de-Ristigouche gold (SAR-Au) showing has peculiar features comparable with Carlin-type gold deposits at the regional, district, and prospect scales. The most striking ones are: (1) the calcareous nature of the host rocks; (2) the Au-As-Sb-Hg metallic signature with absence of base metals and Ag; (3) the association with a crustal scale fault zone; (4) the hydrothermal alteration characterized by silicification, calcite, and quartz veinlets at the margin of the Au-bearing zones and the occurrence of kaolinite in large halos of argillic alteration; (5) numerous felsic dikes; (6) the occurrence of Au in As-rich pyrite forming overgrowths on premineralization As-free pyrite, and in arsenopyrite; (7) hydrothermal fluids equilibrated with host rocks at high temperature (>200°), which cooled to precipitate arsenopyrite and then mixed with evolved meteoric water to precipitate stibnite in veins. Although the SAR-Au showing is relatively small, analogies with Carlin-type mineralization encourage exploration in the Gaspé Peninsula and in similar settings elsewhere in the Appalachians.