Warren Wegener, MSc

The Craigmont Cu-Fe skarn deposit is located in the Quesnel terrane of the Canadian Cordillera in southern British Columbia, adjacent to the Late Triassic Guichon Creek batholith, which hosts the calc-alkalic Highland Valley Cu-Mo porphyry district. Skarn-style mineralization is restricted to Upper Triassic Nicola Group volcaniclastic and carbonate-rich sedimentary rocks and occurs as actinolite-epidote-magnetite-chalcopyrite skarn and specular hematite-chalcopyrite±K-feldspar breccias. 

Previous research suggested the Guichon Creek batholith only acted as a heat source to the skarn mineralization in Nicola Group host rocks. Recent drilling, however, has revealed porphyry-type alteration that occurs pervasively or as vein halos within the Guichon Creek Border phase (diorite to quartz-diorite) adjacent to the historic Craigmont mine. Field and microXRF petrographic studies on both Border phase and Nicola Group rocks show  K-feldspar-biotite, epidote-chlorite, and sericite-quartz±chlorite alteration. Vein types include K-feldspar-chalcopyrite-pyrite-(±molybdenite ±bornite), epidote-chlorite, and quartz. Chalcopyrite, bornite, and molybdenite are typically associated with K-feldspar-biotite alteration.

The LA-ICP-MS U-Pb zircon date of 216±1.1 Ma and molybdenite Re-Os date of 214.1±0.9 Ma obtained in this study are older than previously published dates for the Highland Valley District (211-206 Ma), suggesting there is likely an earlier mineralizing event at Craigmont than previously recognized in the district. Although these two new dates overlap within uncertainty, this does not yet definitively link them as related to the same mineralizing event. Further petrography and U-Pb geochronology on intrusive rocks and U-Pb garnet geochronology of skarn mineralization at Craigmont will be conducted to define the temporal links between skarn, porphyry, and the Guichon Creek batholith.