The Hunker Creek area is located 30 km southeast of Dawson City, Yukon. Gold and sulphide-bearing quartz veins (MINFILE 115O 067, 068) crosscut metamorphic rocks of the Klondike Schist. The veins are enclosed by envelopes of sericitic (inner) and propylitic (outer) alteration. Locally, carbonatization occurs between propylitized and sericitized rocks. Three stages of vein mineralization can be distinguished:: (1) quartz, carbonates, gold, arsenopyrite, pyrite, pyrrhotite, chalcopyrite, and galena; (II) quartz, carbonates, chalcopyrite, sphalerite, tetrahedrite, freibergite, polybasite, 'polyargyrite', argentite, pyrostilbnite and galena; (III) quartz and gold.
Fluid inclusion data indicate that stage I minerals precipitated from hydrothermal solutions containing CO2. Homogenization temperatures range from 260° to 390°C. Stage II aqueous fluid inclusions homogenize between 190° and 260°C. Stage III inclusions homogenize between 120° and 210°C. Salinities of the three stages range from 0 to 7.2 wt-% NaCl equiv. and show no significant changes with time.
It is suggested that stage I mineralization was initiated by unmixing of an original single-phase H2O and CO2 bearing fluid, and that subsequent hydrothermal evolution was controlled mainly by decreasing temperature.
