Abstract: The Stu copper-gold±silver occurrence (Yukon MINFILE 115I 011) is located midway between the Minto and Carmacks Copper deposits in the eastern, Minto suite portion of the Granite Mountain batholith. The best known mineralization at Stu is in Zone A, where at least four foliated and mineralized bodies strike northwest and dip moderately to steeply to the northeast. These bodies grade 0.2 to 0.6% total Cu, though the best historic diamond drill intersection contains 3.5% Cu over 13.5 m. In plan and cross section view, the foliated and mineralized granodioritic orthogneiss bodies pinch and swell, appearing as lenses surrounded by unfoliated K-feldspar porphyritic granodiorite. Copper mineralization occurs as both fine-grained hypogene bornite and chalcopyrite, and supergene malachite, azurite, tenorite and chrysocolla. This study suggests that Stu mineralization is similar to that at the Carmacks Copper and Minto deposits as it is primarily hosted in multiple, discrete bodies of foliated granodioritic rock. In terms of ore body orientation, the moderate to steeply dipping nature at Stu is more reminiscent of Carmacks Copper than Minto, which likely explains the presence of significant supergene copper mineralization.

Authors: P.J. Sack, S. Casselman, D. James and B. Harris

NTS Mapsheet(s): 115I07

Citation: Sack, P.J., Casselman, S., James, D. and Harris, B., 2016. Copper-gold ± silver mineralization at the Stu occurrence, central Yukon (Yukon MINFILE 115I 011), In: Yukon Exploration and Geology 2015, K.E. MacFarlane and M.G. Nordling (eds.), Yukon Geological Survey, p. 207-222.

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