Abstract: Veins in Main Cirque are hosted in major normal fault zones bounding down-dropped blocks to depletion of a magma chamber below the adjacent eruptive centre. Residual heat within the exhausted magma chamber or perhaps a slight resurgence of intrusive material may have driven the hydrothermal circulation which resulted in regional alteration and deposition of the quartz-carbonate veins. Due to the close relationship of these factors, the identification of further eruptive chambers within the volcanic complex as well as any associated collapse features is critical to future exploration. Identification of additional faults associated with the collapse feature represented by Main Cirque is also important because these faults potentially host additional ore.

Gold-silver veins at Mt. Skukum display many of the classic characteristics of a relatively low temperature epithermal system as well as a low-sulphide adularia-sericite system. Vein formation probably occurred within several hundred metres of the paleosurface which may be represented by the intense kaolinitic alteration zone and the crater on the southeastern wall of Main Cirque. The Mt. Skukum deposits likely formed in a near surface environment by circulating meteoric waters in a hydrothermal system driven by a heat source associated with felsic dykes present in the area.

Authors: McDonald, B.W.R., Godwin, C.I., and Stewart, E.B.

Citation: McDonald, B.W.R., Godwin, C.I., and Stewart, E.B., 1986. Exploration geology of the Mt. Skukum epithermal gold deposit, southwestern Yukon. In: Yukon Geology Volume 1, J.A. Morin and D.S. Emond (eds.), Exploration & Geological Services Division, Indian & Northern Affairs Canada, p. 11-18.

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