Origin of the Eskay Creek precious metal-rich volcanogenic massive sulfide deposit; fluid inclusion and stable isotope evidence

The Eskay Creek deposit is an unusual, polymetallic, Au-Ag-rich volcanogenic sulfide-sulfosalt deposit located in the Iskut River area of northwestern British Columbia, Canada. Economic concentrations of precious and base metals are contained in the 21 zone, which is divided into a number of subzones. As of December 31, 1998, total production and proven-probable reserves are 1.9 million tons (Mt) at 60.2 g/t Au, 2,652 g/t Ag, 3.2 percent Pb, 5.2 percent Zn, and 0.7 percent Cu. The 21B zone, which contains the bulk of the reserves, began production in 1995. The mineralization occurs mainly as well-preserved stratiform clastic beds of sulfide-sulfosalt debris and also as discordant footwall quartz sulfide veins.The hydrothermal system that formed the Eskay deposit was low temperature (