A fluid inclusion and stable isotope study of Au quartz veins in the Klondike District, Yukon Territory, Canada; a section through a mesothermal vein system

摘要: Gold-bearing quartz veins in the Klondike district of Yukon Territory are earliest Cretaceous age and hosted by Permian, middle to upper greenschist facies, metasedimentary meta-igneous lithologies belonging Yukon-Tanana terrane. The occur brittle, extensional structures, which may have developed during deformation uplift region Late Jurassic Early Cretaceous, following thrust imbrication Jurassic. massive unbanded, with localized carbonate flooding and/or pyritization wall rocks.Fluid inclusion studies delineated significant, regional P-T-X trends primary fluids from Au veins. low salinities (<6 wt % NaCl equiv), but variable CO 2 concentrations, decreasing approximately 0.13 0.18 mole fraction southeastern Klondike, through concentrations central (X (sub ) < 0.01 [asymp] 1.00), dominantly aqueous 0.01) northwest portion region. Estimated trapping pressures decrease 2,300 + or - 700 bars between 300 900 bars, southeast northwest. fluid temperatures range degrees 350 C southern lodes, 200 250 Klondike. P-X interpreted as evidence for (1) effervescence mineralizing fluid, most likely response life hydrothermal system, (2) that vein system represents a section mesothermal deeper structural levels exposed Convection been driven an elevated geothermal gradient resulting rapid uplift.The calculated isotopic composition (delta 18 O 8.3 1.2ppmSMOW, delta D -150 18ppmSMOW) indicates was meteoric origin underwent considerable evolution prior mineralization. Additionally, values extracted (-166 11ppm) muscovites (-174 3ppm) Sheba good agreement indicate deuterium signature reflects fluid.