Geological Setting and Characteristics of the Red Chris Porphyry Copper-gold Deposit, Northwestern British Columbia





The Red Chris Cu-Au deposit (522.7 Mt at 0.35% Cu and 0.27 g/t Au),
northwestern British Columbia, is one of several pre-accretionary porphyry
systems in the Cordillera of western Canada. It is hosted by an Early Jurassic
hornblende monzonite to quartz monzodiorite porphyry which forms part of a suite
of dikes and stocks that intrude Late Triassic volcanic strata. Major and trace
element chemical data suggest that these Early Jurassic intrusions have
compositions which fall on the boundary between alkalic and calc-alkalic
compositions. Alteration and mineralization in the Red Chris deposit are more
typical of calc-alkaline porphyry systems with abundant potassic, sericitic and
argillic assemblages and quartz-rich stockworks. It lacks Na- and Ca-bearing
silicate assemblages which characterize the alkalic porphyry deposits of British
Columbia. One of the more unusual features of the deposit is the abundance of
carbonate alteration and veins which occur throughout the hydrothermal history
of the deposit. This type of alteration and veining is more typical of alkalic
porphyry deposits. The composition of the carbonates vary both temporally and
spatially with different alteration zones. Potassic zones, which are
characterized by orthoclase±albite±quartz±chalcopyrite±bornit±
magnetite±hematite and Au/Cu ratios of 1:1 (g/t Au:% Cu), contain minor siderite
veins and alteration. Quartz-sericite-carbonate (QSC) zones overprint earlier
potassic alteration and comprise quartz+ankerite+sericite+pyrite+chalcopyrite
with Au/Cu ratios of 0.5:1 (g/t Au:% Cu). Ankerite is the main carbonate in this
stage but has a variable composition with a more Fe-rich variety associated with
mineralized veins. Localized chlorite-carbonate alteration zones, characterized
by chlorite+carbonate+quartz±kaolinite±pyrite±gypsum and high Au/Cu ratios [2 to
3.5:1; (g/t Au:% Cu)], contain predominantly calcite. Late stage
carbonate-gypsum veins have an ankerite to dolomite composition which is very
similar to the regional carbonate alteration and veins.
Keywords: Red Chris deposit, Cu-Au deposit, Porphyry, Carbonate
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Summary: The Geological Society has its own quarterly journal called Exploration
and Mining Geology, for the publication of Canadian and international papers on
applied aspects of mineral exploration and exploitation, including mineral
deposit geology, geochemistry, and geophysics, mining geology, mineral resource
appraisal and estimation methods, environmental geology, and case histories. The
editor of the journal is Jeremy P. Richards
Publication: Exploration & Mining Geology
Issue: 4
Volume: 6
Year: 1997
Web Page
Summary: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
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<BODY>The Canadian Shield and its extensions are traversed by an orthogonal
system of northwest and northeast trending arch-style uplifts. These basement
arches were formed by repeated vertical movements along pre-existing structures
during compressional and extensional tectonism...
Publication: Exploration & Mining Geology
Author(s): K.D. CARD: Card and Associates’ Geosearch, 86 Penfield Drive, Kanata, Ontario, Canada, K2K 1M1; B.V. SANFORD: 17 Meadowglade Drive, Nepean, Ontario, Canada, K2G 5J4; G.M. CARD: Card and Associates’ Geosearch, 86 Penfield Drive, Kanata, Ontario, Canada, K2K 1M1
Keywords: Canadian Shield, Uplifts, Basement arches, Techtonism, Magnetism
Issue: 4
Volume: 6
Year: 1997
Text
Summary: Eclogite is an important source of diamond in the upper mantle, but is more localized than peridotite. Using eclogitic minerals in kimberlite and diamond exploration is also more problematic than using the well-known peridotite-derived indicator minerals Cr-pyrope and magnesiochromite. The problems include color similarities between orange garnets from eclogites, Cr-poor megacrysts, and crustal garnets, chemical similarities with Cr-poor megacryst suite garnets (specifically elevated Na2O...
Publication: Exploration & Mining Geology
Author(s): DANIEL J. SCHULZE: Department of Geology, University of Toronto, Erindale College
Mississauga, Ontario, Canada L5L 1C6
Keywords: Eclogite, Diamond, Kimberlite exploration, Diamond exploration
Issue: 4
Volume: 6
Year: 1997
Text
Summary: The presence of fine-grained mineral intergrowths, the complex distribution of deleterious minor elements, and the variable base-metal contents in some assemblages commonly pose technical problems for the processing of volcanogenic massive sulfide ores. The beneficiation of most massive sulfide ores from the Iberian Pyrite Belt requires extremely fine grinding to liberation sizes of K80 = 15 µm to 25 µm. For several deposits, mapping of the ore types and metal zoning patterns has shown that...
Publication: Exploration & Mining Geology
Author(s): ORLANDO C. GASPAR: Laboratório do Instituto Geológico e Mineiro, 4465 S. Mamede de Infesta, Portugal
Keywords: Mineral intergrowth, base metal, Volcanogenic massive sulfide ores, Iberian Pyrite Belt
Issue: 4
Volume: 6
Year: 1997
Text
Summary: The acid rock drainage (ARD) buffering capacity of mine waste is governed by its bulk chemical composition and its mineral assemblage. Conventional acid base accounting (ABA) tests can be used to predict short-term buffering, but should be used with caution to model or predict the long-term ARD buffering capacity of mine waste. ABA data for mine waste samples from four different deposit types: anorthosite-hosted magmatic sulfide nickel, dunite-hosted magmatic sulfide nickel, porphyry...
Publication: Exploration & Mining Geology
Author(s): BRUCE W. DOWNING: Gamah International Limited, Vancouver, British Columbia, Canada; HANS E. MADEISKY: HEMAC Exploration Ltd., Vancouver, British Columbia, Canada
Keywords: Acid rock drainage, ARD, Mine waste, Acid base accounting, ABA
Issue: 4
Volume: 6
Year: 1997
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Summary: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META content="text/html; charset=unicode" http-equiv=Content-Type>
<META name=GENERATOR content="MSHTML 9.00.8112.16440"></HEAD>
<BODY>Narrow veins are an important world-wide source of silver, tin, uranium
and particularly gold. To potential financiers, this style of mineralization is
viewed as high risk because of the often relatively small resource involved and
high cost of estimation. In many cases diamond...
Publication: Exploration & Mining Geology
Author(s): SIMON C. DOMINY: Mining Geology Group, School of Earth and Environmental Sciences, University of Greenwich, Chatham Maritime, Kent ME4 4TB, U.K., and
Welsh Gold Plc, Northwood, Middlesex HA6 3LY, U.K.; ALWYN E. ANNELS: Mining Geology Group, School of Earth and Environmental Sciences, University of Greenwich, Chatham Maritime, Kent ME4 4TB, U.K.; Steffen, Robertson & Kirsten (UK) Ltd, Cardiff CF1 3BX, Wales, U.K.; G. SIMON CAMM, PAUL WHEELER: Department of Geology, Camborne School of Mines, Unive
Keywords: Geology, Narrow veins, Silver, Tin, Uranium, Gold, Mineralization, Geological study
Issue: 4
Volume: 6
Year: 1997
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