The Mount Nansen camp hosts approximately 30 mineral occurrences of epithermal and porphyry origin. The largest occurrence is the Brown-McDade with approximately 600 000 tonnes of drill-indicated reserves at 6.1 g/t Au and 55.5 g/t Ag. The majority of the northwest-striking, steeply dipping epithermal quartz/sulphide veins are found within a 12 km long by 3 km wide northwest-trending corridor called the Nansen trend. The precious-metal-bearing veins occur in all lithologies within the Nansen trend and contain (in order of decreasing abundance) pyrite, arsenopyrite, galena, sphalerite, chalcopyrite, stibnite and tetrahedrite. Two types of epithermal veins are recognized: an early “cherty” quartz-sulphide vein with fine-grained pyrite and arsenopyrite; and a later coarse-grained quartz-sulphide vein with pyrite, galena and sphalerite and higher precious metal values. Within the trend is the Mount Nansen porphyry complex which hosts two cores of potassic alteration. The character of mineral occurrences varies with increasing distance away from these Central Porphyry Zone and are here recognized as the Peripheral Porphyry, Transitional and Epithermal zones. Together, they comprise a porphyry-to-epithermal transition. Placer mining is predominant on creeks draining from the porphyry complex, implying a porphyry source for the placer gold.
