The geology consists of volcanic and sedimentary rocks belonging to the Paleozoic Sicker Group, the Mississippian to Permian Buttle Lake Group, the Lower Jurassic Bonanza Group, the Upper Triassic Vancouver Group, the Upper Cretaceous Nanaimo Group, and the Jurassic to Cretaceous Leech River Complex. These are intruded by Early to Middle Jurassic Island Plutonic Suite (previously known as the Island Intrusions) granitic rocks and Tertiary dikes and sills (previously known as the Catface Intrusions). The Sicker and Buttle Lake groups occur primarily in the Cowichan Lake area, at the southeastern extent of the Cowichan uplift, and are the main target for volcanogenic massive sulphide deposits. The stratigraphy of the Cowichan uplift has recently been redefined by Geological Survey Branch geologist N.W.D. Massey. A province-wide mineral potential study was launched in 1992 with Vancouver Island as the initial study area. Data resulting from this study are available on the Ministry web-site.

In order of historic importance, base and precious metal mineral wealth has occurred in such varied deposit types as skarns, shears, quartz veins, porphyries and volcanogenic massive sulphides. The numerous and well documented skarns in the Cape Flattery area warrant new exploration to determine the potential for precious metal mineralization. The Monitor high grade copper skarn (092C 007) occurs in the Alberni Canal area. Past production from the Blue Grouse (092C 017) and Sunnyside (092C 108) copper skarns in the Cowichan Lake area totals 6,814,623 kilograms of copper, 2,508,644 grams of silver and 218 grams of gold. The Bugaboo (092C 022) and associated iron-magnetite skarns in the Bugaboo Creek area have combined total reserves of 4,367,000 tonnes (unspecified grade). The Rob skarn (092C 034) in the Cowichan Lake area produced 61,929 kilograms of copper from a test run of 4665 tonnes in 1960. The Reko magnetite skarn prospects (092C 091) have estimated reserves of 4.5 million tonnes grading 22 per cent iron. High copper and gold assays have also been reported from the Reko property.

The Sunro shear-hosted deposit (092C 073) was an active mine between 1962 and 1972, producing 13.7 million kilograms of copper, 200 kilograms of gold and 2,262 kilograms of silver from a total of 1.3 million tonnes mined. This deposit has a remaining probable reserve of 1.47 million tonnes grading 1.43 per cent copper. The Sechart shear-related mercury deposit (092C 065) on the Sechart peninsula has been known since 1890. It has been intermittently developed over the years and today has over 100 metres of tunnels.

The Wet (092C 083) molybdenum prospect is classified as a porphyry-type deposit that occurs in Bonanza Group volcanics intruded by plutonic rocks of the Island Plutonic Suite. Several other molybdenum-copper porphyry deposits are documented in the map area

Rhodonite occurs in a cherty tuff horizon (Mississippian Shaw Creek Member) in the Fourth Lake Formation (Buttle Lake Group) in the Cowichan Lake area extending to the Hill 60 (092B 027) area. The Rocky showing (092C 113) produced 555 kilograms of rhodonite from surface stripping in 1977 and 1978.

Placer gold has been mined, particularly from coastal areas. Sixteen occurrences exist with limestone as the primary commodity.

SELECTED REGIONAL REFERENCES (NTS 092C - CAPE FLATTERY)

Carson, D.J.T. (1968): Metallogenic Study of Vancouver Island with Emphasis on the Relationship of Plutonic Rocks and Mineral Deposits, Ph.D. Thesis, Carleton University.

Carson, D.J.T. (1973): The Plutonic Rocks of Vancouver Island, British Columbia Geological Survey of Canada, Paper 72-44.

Clapp, C.H. (1912): Southern Vancouver Island; Geological Survey of Canada, Memoir 13 (includes Map 17A).

Clapp, C.H. (1917): Sooke and Duncan Map-areas, Vancouver Island; Geological Survey of Canada, Memoir 96 (includes Maps 41A, 42A, 43A, 44A, 157A and 167A).

Eastwood, G.E.P. (1976): Southern Vancouver Island (NTS 092C/09, /14, 092F/02); B.C. Ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork 1975

Eastwood, G.E.P. (1978): Vancouver Island (092C/15, 092L/07, /11); B.C. Ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork 1977.

Eastwood, G.E.P. (1982): Upper Sutton Creek Area (092C/16); B.C. Ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork 1981.

Eastwood, G.E.P. (1985): 1977 - Upper Renfrew Creek Area (092C/09W); B.C. Ministry of Energy, Mines and Petroleum Resources, Geology in British Columbia, 1977-1981.

Eastwood, G.E.P. (1983): Leach River Area, Vancouver Island; B.C. Ministry of Energy Mines and Petroleum Resources, Geological Fieldwork 1982.

Eastwood, G.E.P. (1985): 1977 - Vernon Ridge Area (092C/15E, /16W); B.C. Ministry of Energy, Mines and Petroleum Resources, Geology in British Columbia, 1977-1981.

Fyles, J.T. (1955): Geology of the Cowichan Lake Area; B.C. Ministry of Energy, Mines and Petroleum Resources, Bulletin 37.

Gravel, J.L., Jackaman, W., Matysek, P.F. (1990): 1989 Regional Geochemical Survey, Southern Vancouver Island and Lower Mainland (92B, 92C, 92F & 92G); B.C. Ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork 1989.

Hudson, R. (1997): A Field Guide to Gold, Gemstone and Mineral Sites of British Columbia, Vol. 1: Vancouver Island; Orca Book Publishers, pp. 72-79, 96-110.

Massey, N.W.D. and Friday, S.J. (1987): Geology of the Cowichan Lake Area, Vancouver Island; B.C. Ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork 1986.

Massey, N.W.D., Friday, S.J., Tercier, P.E., Rublee, V.J. (1987): Geology of the Cowichan Lake Area, Vancouver Island; B.C. Ministry of Energy, Mines and Petroleum Resources, Open File Map 1987-2, 1:20,000.

Massey, N.W.D. and Friday, S.J. (1988): Geology of the Port Alberni - Nanaimo Lakes Area, Vancouver Island; B.C. Ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork 1988.

Massey, N.W.D., Friday, S.J., Tercier, P.E., Potter, T.E. (1987): Geology of the Duncan and Chemainus River Area, Vancouver Island; B.C. Ministry of Energy, Mines and Petroleum Resources, Open File Map 1988-8, 1:20,000.

Massey, N.W.D. and Friday, S.J. (1988): Geology of the Chemainus River - Duncan Area, Vancouver Island; B.C. Ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork 1987.

Massey, N.W.D., Friday, S.J., Riddell, J.M., and Dumais, S.E. (1991): Geology of the Port Alberni - Nanaimo Lakes Area; B.C. Ministry of Energy, Mines and Petroleum Resources, Geoscience Map 1991-1, 1:50,000 (with Paper 1992-2).

Massey, N.W.D., Friday, S.J., Tercier, P.E., Rublee, V.J. and Potter, T.E. (1991): Geology of the Cowichan Lake Area; B.C. Ministry of Energy, Mines and Petroleum Resources, Geoscience Map 1991-2, 1:50,000 (with Paper 1992-3).

Massey, N.W.D., Friday, S.J., Tercier, P.E., Potter, T.E. (1991): Geology of the Duncan Area; B.C. Ministry of Energy, Mines and Petroleum Resources, Geoscience Map 1991-3, 1:50,000 (with Paper 1992-4).

Massey, N.W.D. (1992): Geology and Mineral Resources of the Alberni - Nanaimo Lakes Sheet; B.C. Ministry of Energy, Mines and Petroleum Resources, Paper 1992-2.

Massey, N.W.D. (1992): Geology and Mineral Resources of the Cowichan Lake Sheet; B.C. Ministry of Energy, Mines and Petroleum Resources, Paper 1992-3.

Massey, N.W.D. (1992): Geology and Mineral Resources of the Duncan Sheet; B.C. Ministry of Energy, Mines and Petroleum Resources, Paper 1992-4.

Massey, N.W.D. (1992): Mineral Potential of the Duncan Area; B.C. Ministry of Energy, Mines and Petroleum Resources, Mineral Potential Map 1992-3.

Massey, N.W.D. (1994): The Vancouver Island Mineral Potential Project (92B, C,F,G,K,L and 102I; B.C. Ministry of Energy, Mines and Petroleum Resources, Geological Fieldwork 1994.

Massey, N.W.D. (1995): Geological Compilation, Vancouver Island, B.C. Ministry of Energy, Mines and Petroleum Resources, Open File 1994-6, 1: 250,000.

Muller, J.E. (1977): Geology of Vancouver Island; Geological Survey of Canada, Open File 463, 1: 250,000.

Muller, J.E. (1980): The Paleozoic Sicker Group of Vancouver Island, British Columbia; Geological Survey of Canada, Paper 79-30.

Northcote, K.E. (1973): The Geology of the Nitinat Triangle (092C/10, /15); B.C. Ministry of Energy, Mines and Petroleum Resources, Geology, Exploration and Mining in British Columbia.

Roddick, J.A., Muller, J.E. and Okulitch, A.V., Compilers (1976): Fraser River; Geological Survey of Canada, Map 1386A, 1: 1,000,000.

Rusmore, M.E. (1982): Structure and Petrology of Pre-Tertiary Rocks Near Port Renfrew, Vancouver Island, unpublished M.Sc. Thesis, University of Washington.

BC Geological Survey Publications for NTS 092C