Metallogenesis and Tectonics of the Russian Far East, Alaska, and ...

stage albite and peripheral propylitic alteration. Potassic and scapolitic alteration crosscuts albite and propylitic alteration (Ross
and others, 1992, 1993, 1995). The Afton deposit consists of a tabular-shaped body of chalcopyrite and bomite which is hosted in
fractured diorite of the Cheny Creek pluton. A deeply penetrating supergene zone contains native copper and lesser chalcocite.
Aggregate pre-production reserves and production for the Ajax East and West deposits and for the Afton deposit are 66 million
tonnes grading 0.77% Cu and 0.56 glt Au. The common occurrence of picrite intrusions along faults which cut the Nicola Group and
their association with the porphyry deposits in the Iron Mask pluton indicate which regional, steeplydipping faults controlled
emplacement of the plutons in the batholith and also served as conduits for mineralizing fluids. An U-Pb zircon isotopic age of 207 Ma
(Late Triassic) for the Cheny Creek pluton.
Deep drilling in 2001-2002 southwesl of and below the Afton orebody by DRC Resources Corporation has proven a
resource of 34.3 million tonnes of 1.55% Cu, 1.14 g/t Au, 3.42 g/t Ag and 0.125 g/t Pd in the Main Zone, and an additional 1.1
million tonnes of similar material in the Northeast Zone. The roughly tabular body is 850 m long, 750 m deep, and 70 m wide, and
is open to length and depth. The deposit exhibitsboth hydrothermal and magmatic characteristics (DRC Resources Corp, news
release April 2003).
Mt. Polley (Cariboo-Bell) Porphyry Cu-Au Deposit
The Mt. Polley (Cariboo-Bell) Porphyry Cu-Au deposit consists of magnetite, chalcopyrite and minor pyrite which occur
in several intrusive phases and three distinct breccias in an Early Jurassic pseudoleucite-bearing alkaline complex which intrudes
Upper Triassic Nicola alkaline volcanic and volcaniclastic rocks of the Quesnel trough (EMR Canada, 1989; McMillan, 199 1;
Mining Review, 1991; Gosh, 1992; Fraser and others, 1993; MINFILE, 2002). Some skarn and vein occurs in tuff and flows of
the Nicola Assemblage. Supergene mineralization includes malachite, native copper, cuprite, chalcocite and covellite. The deposit
contains proven reserves of 76.5 million tomes grading 0.30% Cu, 0.47 g/t Au. Production through 1999 was 15.26 million
tonnes with 341,000 g Ag, 6,858,448 g Au, and 31,637,173 kg Cu (MINFILE, 2002). A U-Pb zircon isotopic age of 200 * 1.5
Ma for diorite and a monzonite porphyry indicates an Early Jurassic age for intrusion of the host granitoid rocks.
Lodestone Mountain Zoned Mafic-Ultramafic Fe-Ti Deposit
The Lodestone Mountain zoned mafic-ultramatic Fe-Ti deposit consists of titaniferous magnetite and ilmenite which
occur in pods and lenses and as disseminated grains in pyroxenite of the Tulameen zoned mafic-ultramafic (Alaskan type)
complex (St. Louis and others, 1986; Nixon and others, 1997). The deposit contains estimated reserves of 8 1.65 million tonnes
grading 17.56% Fe (EMR Canada, 1989). Minor Pt and Pd are reported. Reported Ti content of magnetite is 1%. An additional
249 million tons of possible and inferred ore is estimated. The deposit is interpreted as forming primarily by magmatic
differentiation. The Late Triassic Tulameen layered mafic-ultramafic (Alaskan-type) complex is coeval, and in part cogenetic with
adjacent gabbro plutons of the Lost Horse intrusive complex (Findlay, 1969). The complex intrudes basaltic andesite of the Nicola
Group. Several lode and placer Pt-Pd deposits occur at Grasshopper Mountain in the Tulameen Complex (Findlay, 1969).
Origin of and Tectonic Controls for
Copper Mountain (South) Metallogenic Belt
The Copper Mountain (South) metallogenic belt is hosted in the Copper Mountain plutonic suite. Syenite, rnonzonite, and
monzodiorite are most common, but diorite, monzogranite, clinopyroxenite occur locally. The porphyry Cu-Au deposits are hosted
in the felsic plutons, whereas the major Fe-Ti deposit at Lodestone Mountain is hosted in zoned mafic-ultramafic rocks. Many
felsic plutons are lithologically and texturally complex, with multiple phases of intrusion and potassic metasomatism,
characterized by abundant apatite and magnetite. Some plutons are nepheline-and leucite-normative; others are both quartz-
saturated and quartz-undersaturated (Woodsworth and others, 1991 ). The deposits in the Copper Mountain (South) and (North)
metallogenic belts are part of the subduction related Quesnellia island arc (Monger and Nokleberg, 1996; Nokleberg and others,
2000). In both the Copper Mountain (North) and Copper Mountain (South) metallogenic belts, many of the porphyry CU-AU
deposits occur in alkaline plutons. Isotopic ages indicate intrusion of host granitoid plutons and formation of associated mineral
deposits occurred from about 207 to 197 Ma in the Late Triassic and Early Jurassic (Ross and others, 1995; Stanley and others,
1995). This age represents the end of subduction-related igneous building of Quesnellia island arc, just before accretion of the
Quesnellia terrane, along the with tectonically-related Stikinia island arc and Cache Creek and Slide Mountain subduction-zone
terranes, onto the North American Craton Margin (Monger and Nokleberg, 1996; Nokleberg and others, 2000).
Guichon Metallogenic Belt of Porphyry Cu-Mo-Au
and Au Skam Deposits
(Belt GU) Southern British Columbia
The Guichon metallogenic belt of porphyry Cu-Mo-Au and Au skarn deposits (fig. 32; tables 3,4) occurs in southern
British Columbia and is associated with the Guichon Suite of numerous large calc-alkaline granitoid plutons hosted by the western
Quesnellia island-arc terrane. The Guichon Suite has close spatial and temporal affinities with the Late Triassic and Early Jurassic