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Ministry of Energy Mines and Responsible for Core Review

Geoscience Map 1991-2: Geology of the Cowichan Lake Area
NTS (92C/16)

by N.W.D. Massey, S.J. Friday, P.E. Tercier, V.J. Rublee and T.E. Potter

View Map (PDF 7.9MB)
Scale 1:50 000
See Paper 1992-3


Geoscience Map 1991-2 describes the geology of the Cowichan Lake area. It is a 1:50 000scale map covering the southwestern flank of the Cowichan uplift. North of Cowichan Lake, the area is underlain by island-arc volcanics of the Devonian Sicker Group and marginal basin and platformal sediments of the Mississippian to Lower Permian Buttle Lake Group.  South of the lake, separated from the Paleozoic sequence by the Cowichan fault, Mesozoic volcanics and sediments form a broad anticline.  The Upper Triassic basalts and sediments of the Karmutsen, Quatsino and Parson Bay formations are overlain by arc volcanics of the Lower Jurassic Bonanza Group. Granodiorite stocks and plutons of the early to middle Jurassic Island plutonic suite intrude all older sequences. Clastic sediments of the Upper Cretaceous Nanaimo Group occur throughout the map area, preserved in the footwalls of major contractional faults associated with the Eocene fold and thrust system.  The map sheet contains 39 documented mineral deposits and occurrences, though past production has been limited to the copper skarn deposit of the Blue Grouse mine.  Other mineralization includes lode gold, base metal veins, porphyry copper-molybdenum veins and stockworks, volcanogenic exhalites, rhodonite, limestone and placer gold.


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