General Information
Abstract: The Mount Skukum Volcanic Complex (MSVC) is the northernmost extension of the Sloko volcanic province in western British Columbia, a broad northwest-trending volcanic belt along the northeast margin of the Coast Plutonic Belt. Rocks of the Sloko volcanic province are preserved as downfaulted blocks and as erosional remnants on higher upland surfaces. They comprise an assemblage of intermediate to felsic volcanic rocks and derived sedimentary rocks that lie unconformably on Cretaceous granitic rocks, folded Jurassic rocks and Precambrian (?) metasedimentary rocks.
The MSVC is Paleocene-Eocene in age, and elliptical in plan; it covers an area of about 140 km squared. It is a downfaulted volcanic block, deposited on Cretaceous granitic rocks of the Ruby Range Batholith and older metasedimentary rocks of the Yukon Group. The complex is surrounded peripherally by several high-level rhyolite intrusions which have recently been dated at 53 ±1.1 Ma using rubidium-strontium geochronology.
The MSVC has a maximum vertical thickness of 850 m. It includes:: 1) a downfaulted part of an andesitic stratovolcano which forms the western and southern parts of the complex and comprises the distal and medial facies assemblage of Formations 1 and 2, and the more proximal facies assemblage of Formation 3 a small felsic cauldron subsidence structure in the northeast corner of the area represented by the felsic cauldron-fill deposits of Formation 4; 3) an andesitic vent facies environment located in a small area in the midwestern part of the complex and comprising the deposits of Formation 5; and 4) a central quartz-feldspar-phyric rhyolite intrusion along the western boundary of the small felsic cauldron.
A NNE-trending fracture system is the dominant and perhaps the latest structural feature in the MSVC. Economic epigenetic gold veins are found in three major subparallel NNE-trending fault zones. The veins consist of quartz and calcite and are unusual in that they contain no sulphides and have poorly developed wall rock alteration. As of February 1984, the average grade was 27 g/t gold and 22.63 g/t silver with proven reserves of 149,114 tonnes.
The MSVC is Paleocene-Eocene in age, and elliptical in plan; it covers an area of about 140 km squared. It is a downfaulted volcanic block, deposited on Cretaceous granitic rocks of the Ruby Range Batholith and older metasedimentary rocks of the Yukon Group. The complex is surrounded peripherally by several high-level rhyolite intrusions which have recently been dated at 53 ±1.1 Ma using rubidium-strontium geochronology.
The MSVC has a maximum vertical thickness of 850 m. It includes:: 1) a downfaulted part of an andesitic stratovolcano which forms the western and southern parts of the complex and comprises the distal and medial facies assemblage of Formations 1 and 2, and the more proximal facies assemblage of Formation 3 a small felsic cauldron subsidence structure in the northeast corner of the area represented by the felsic cauldron-fill deposits of Formation 4; 3) an andesitic vent facies environment located in a small area in the midwestern part of the complex and comprising the deposits of Formation 5; and 4) a central quartz-feldspar-phyric rhyolite intrusion along the western boundary of the small felsic cauldron.
A NNE-trending fracture system is the dominant and perhaps the latest structural feature in the MSVC. Economic epigenetic gold veins are found in three major subparallel NNE-trending fault zones. The veins consist of quartz and calcite and are unusual in that they contain no sulphides and have poorly developed wall rock alteration. As of February 1984, the average grade was 27 g/t gold and 22.63 g/t silver with proven reserves of 149,114 tonnes.
Authors: Pride, M.J.
Citation: Pride, M.J., 1986. Description of the Mount Skukum Volcanic Complex, southern Yukon. In: Yukon Geology Volume 1, J.A. Morin and D.S. Emond (eds.), Exploration & Geological Services Division, Indian & Northern Affairs Canada, p. 148-160.
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Related Publications
| Number | Relationship | Authors | Title |
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| 1986GeolVol1 | Contained By | Morin, J.A. and Emond, D.S. (eds.) | Yukon Geology Volume 1 |
