Stratigraphic control of Cu-Fe skarn ore distribution and genesis at Craigmont, British Columbia

Abstract margin of the late Triassic Guichon Creek batholith in south-central British Columbia. Host to the ore are sedimentary and volcanic rocks of the western calc-alkaline belt of the Upper Triassic Nicola Group. In the mine area, the Nicola Group rocks are a stratigraphically complex sequence, at least 1800 feet thick, which have been subdivided into Basalt, Rhyolite, Carbonate and Clastic Sediment units. All the units strike and dip parallel to the margin of the Guichon Creek batholith and are within the batholith contact aureole. However, only the Clastic Sediment unit is in contact with the batholith.Most of the skarn and ore is within the Carbonate unit and more specifically within an Interbedded fades that consists of lime sandstone, lime siltstone, quartzo-feldspathic siltstone and argillite. The Interbedded fades and the adjacent barren Massive Limestone fades are interpreted as part of a carbonate reef complex. The distribution of skarn and ore within the Interbedded fades suggests that the fades boundary was a physical and chemical barrier that resulted in concentration of metals adjacent to the Massive Limestone fades.Two stages of skarn formation have been recognized at Craigmont. In Stage I, ore-bearing magnetite-rich and actinolite-epidote-magnetite skarns developed both in basaltic rocks and in Fe-bearing siltstone and argillite of the Interbedded fades, while barren grossular garnet-epidote-caldte-pyrite skarns developed in Fe-poor rhyolitic bands within the Interbedded and Massive Limestone fades. In Stage II, massive, barren grandite garnet skarn replaced mineralized Stage I skarns in the vicinity of diorite plugs and specularite ore formed in brecdated Stage I skarn and clastic rocks away from the plugs. The formation of Stage I skarns required no addition of material, only redistribution and concentration of elements already present within the Interbedded fades. However, the concentration of Cu in Stage I ore requires a mechanism for more efficient leaching of Cu from the host rocks, an anomalous concentration of Cu at the site of the Stage I orebody or an additional input of Cu from an external source. The formation of Stage II skarn and ore requires only remobilization and recrystallization of Stage I skarn and ore.Copper and iron are the only elements in economic concentrations in the ore and chalcopyrite is the only significant copper-bearing mineral. Chalcopyrite is disseminated and interstitial to magnetite in Stage I mineralized skarns and is interstitial to specularite in the matrix of Stage II breccia ores. Chalcopyrite also occurs with pyrite as stringer ore in bleached -sediments and rhyolite tuffs in the Stratigraphic foot wall of the main orebodies.The Craigmont deposit has more features in common with Cu-Fe deposits hosted in metavolcanic and metasedimentary rocks than it has with typical skarn deposits associated with porphyry copper deposits. The orebody is more likely a product of concentration of metal contained within the Nicola Group rocks than of the mineralizing event that produced the Highland Valley Cu-Mo porphyry deposits in the central part of the Guichon Creek batholith.
Keywords: Stratigraphy, Copper, Iron, Skarn, Craigmont mine, Nicola Group, Guichon Creek batholith, Contact aureoles.
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Publication: CIM Bulletin
Author(s): AL HOLMES
Issue: 820
Volume: 73
Year: 1980
Text
Publication: CIM Bulletin
Author(s): P.E. WEIDMARK
Issue: 820
Volume: 73
Year: 1980
Text
Summary: The use of approved fire-resistant hydraulic fluids in equipment operating underground was made mandatory in British Columbia by amendment to the Provincial Mines Regulation Act effective January 1, 1975. This paper covers the action taken to achieve this, in the largest underground metal mine in British Columbia. Some evaluation of costs and effects based on experience to date is included.
Publication: CIM Bulletin
Author(s): J.W. REYNOLDS
Keywords: Fluids, Fire-resistant fluids, Hydraulic systems, Sullivan Mine, Safety.
Issue: 820
Volume: 73
Year: 1980
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Summary: The history and analysis of a structurally complex open-pit rock slope displacement are described. The failure involved part of the only haulage access to a major ore zone. The ongoing movement was monitored using an electronic distance-measuring device and a continuous electronic system specifically designed for the problem. A major fault, infilled with a thick clay gouge, and intersected by other structural features, resulted in the transfer of weight to a rock mass acting as a buttress in...
Publication: CIM Bulletin
Author(s): PETER N. CALDER
Keywords: Rock mechanics, Slope displacements, Pit slopes, Brenda Mines, Faults, Blasting, Monitoring systems, Failure analysis, Safety factors, Drainage.
Issue: 820
Volume: 73
Year: 1980
Text
Summary: A morphological and chemical study of the Great Canadian Oil Sands Ltd. (GCOS) fly ash has been carried out. Extensive scanning electron microscopy, as well as light microscopy, showed that the GCOS fly ash consists of two fractions, one composed of unburnt or partially burnt irregular-shaped carbon particles and an ash fraction composed of transparent and opaque, often coloured, glassy spherical particles—some of them cenospheres (hollow spheres) and the othersplerospheres (hollow...
Publication: CIM Bulletin
Author(s): C.O. GOMEZ BUENO, G.L REMPEL, D.R. SPINK
Keywords: Mineral processing, Athabasca tar sands, Fly ash, Microcrystals, Size fractions, Environmental control
Issue: 820
Volume: 73
Year: 1980
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Summary: A unique deposit of barite exists near Brookfield, Nova Scotia. The crystals are extremely fine and the whole deposit virtually free of heavy metals. The deposit size was not large enough for conventional uses, such as the production of barium carbonate and drilling mud. In an effort to obtain maximum utilization, a program was begun to determine if U.S.P.-grade pharmaceutical barium sulphate for X-ray diagnosis could be produced.Early work was sufficiently encouraging to institute a...
Publication: CIM Bulletin
Author(s): W.J.D. STONE, J.D. NYE, I.R. FARR
Keywords: Industrial minerals, Barite, Barium sulphate, Magstone Development Inc., Paddle mills, Jones magnetic separator.
Issue: 820
Volume: 73
Year: 1980
Text
Summary: Detailed studies have been conducted on the dispersion of uranium in stream waters and sediments around various types of mineralization and hitherto unexplained anomalous areas in the Okanagan Valley and Highland region of south-central British Columbia. These studies were part of the jointly funded and planned Federal-Provincial Uranium Reconnaissance Program of the Geological Survey of Canada and the British Columbia Ministry of Energy, Mines and Petroleum Resources. Statistical analysis of...
Publication: CIM Bulletin
Author(s): D.R. BOYLE, S.B. BALLANTYNE
Keywords: Geochemistry, Uranium dispersion, British Columbia, Stream waters, Sediments, Draining systems, Lassie Lake area, Grand Forks area, Beaverdell area, Midway area, Blue Springs area, Okanagan region.
Issue: 820
Volume: 73
Year: 1980
Text
Summary: The low cost and availability of micro-computers and their peripherals provides the metallurgical engineer with the opportunity to use such computers in a wide variety of applications. In this paper, the authors describe the development of a low-cost data acquisition system capable of measuring up to 8 analogue channels at a sampling rate of up to 5000 measurements per second. This system is equipped with proper hardware and software so that the micro-computer can be linked to a central...
Publication: CIM Bulletin
Author(s): S.A. ARGYROPOULOS, R.I.L. GUTHRIE, K. ANANTHANARAYANAN
Keywords: Computers, Microprocessors, Process metallurgy, Dissolution kinetics, Steel baths, Castings.
Issue: 820
Volume: 73
Year: 1980
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