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

Zone are 188 million tonnes grading 0.42% Cu, 0.0 14% Mo, and 308 million tonnes grading 0.37% Cu, 0.1% Mo; ptmtial for
additional resources exists at depth (McDougall, 1976; Enns and McDougall, 1995).The deposit is hosted in an apophysis of
Eocene porphyritic quartz diorite of lbc Catface plutonic suite and has a K-Ar isotope agt of 48 Ma. The diorite intrudes rsfatively
older quartz monzonite and rnttabasalt of the Late Triassic Karmuum Formation of WmgeUia.
The Domineer-Lakeview Au-Ag polyrnetallic vein zone occurs at Mount Washington, near Comox, and consists of a
silicified vein-shear zone which cuts basaltic volcanic rocks of the Late Trimsic Kanmrtsen Formation sed'intaxy nxks of tbe
Late Cretaceous Nanaimo Group, and sills of the Catface Plutonic Suite. The Au-Ag polyrmtallic vein zone k iaterpteted as a
shallow-dipping, post intrusjon body. The shear zone is intensely altered to kaolinite ~d cordah t&uh zones which are
silicified and cut by Au veins with quartz, pyrite, and arsenopyrite. The deposit is aesociated with a small, previously-pmhxing
porphyry Cu-Mo deposit, and several minaalized breccia pipes. Estimated reserves are 550,298 tomes grading 6.75 g/t Auand
32.2 g/t Ag (Muller and Carson, 1969; MWFILE, 2002).
The Privateer Au polyme~llic vein deposit consists of a set of &in, ribbon qwtz veins which ml contactmetamorphosed
volcanic rocks of the Middle Jurassic Bonarua Group, as well as LLe ZeWs stock ofthe Ca&ce Plutmh Suite.
The Privateer is the largest and most productive of a group of small miuer in and adjacent to the W. Thc mjM ore mined are
abundant pyrite and arsenopyrite, sphalerite, less abundant chalcopyrite, galena, and pyrrhotite, and rare free gold. Estimated
production is 280,000 tonnes of are containing 18.8 g/t Au a1008 with Ag, W, and Zn (Stevenson, 1950; hwson and others,
1991).
Origin of and Tectonic Controls for
Cafface Metallogenic Belt
The Middle to Late Eocene intmsionsof the bthm Plutonic Suite are mainly calc-alkaline, to&te ad qutlrtk diorite
and minor granodiorite and granite, and comnly porpbyntic. The plulans ~ TC roughly synhnou~ with Pdmgene plutons in
the southern Coast and Intermontane belts, were emplaced at hgh levels as indicated by asm~kted breech^ and &atrema, and
intrude rocks as young as the Late Cretaceous Nanaimo Group (Woodswo~th and &ITS, 1991). The Catfkw Nutonic Suh ia tbe
southern part of the extensive Late Cretaceous and early Tertiary Coast- no^ Casce&e plutonic belt which formed a major
continental-margin arc in mainly tbe western Canadian Cordillera mokleberg and others, 1994c, 1997~; Monger and Noltlebq,
1996).
Metallogenic Belts Formed in Backarc
Part of Early Tertiary Coast
Continental-Margin Arc,
Southern Canadian Cordillera
The Skeena (SK) and Nelson (NS) constitute two major metallogenic belts of granitic-tntigmath-rektwl&@C mcur
in the southern Canadian Cordillera (fig. 103; tables 3.4) that are interpreted as forming during granitic plutmhun wcurring
during back arc extension or transtension m an region contiuentwatd of the subduction-related Coast coatinend--gin arc.
These two early Tertiary two rnetallbgenic belts represent the lest stage of magmatism in the Cosst=&rlh hsade pi& bell
that comprises most of the Coast o&cnral-margin B~C. This period of regional extension or treasteasion in the southern
Canadian Cordillera is interpreted a8 the result of eitber: (1) a chenge horn transpression to tranmmion at abwt 55 M a d by
a change of obliquity of convergence of the oceanic plate (Parrish and othes, 1988); or (2) alternatively. but likely, collapse of
overthickened thrust units (Monger and Nokleberg, 1996; Nokkberg and others, 2000). This origin is d8gou8 to the wcmetlce
of back-arc magmatism forming the Columbia River basalt to the rear of the Cascade arc in theMiocene (Wells and Mel&r3 1988;
England and Wells, 199 1 ; Nokleberg and others, 2000).
Skeena Metallogenic Belt of Porphyry Cu-Mo,
Porphyry Mo; Ag Polymetallic Vein and
Au-Ag Epitherrnal Vein Deposits (Belt SK)
Central British Columbia
The Skeena metallogenic beIt of porphyry Cu-Mo; porphyry Mo; Ag polymetallic vein, atld Au-Ag epithd vein
deposits occurs in central British Columbia (fig. 103; tables 3,4), and is associated with sevd early Teftiary plutdc suiw is
the Intermontane Belt in westcentral British Columbia, inclu~g the Namka, Babine, Quanchus md Gmly (Weodswath md
others, 199 1 ; Carter, 1982). Coeval and spatially related volczlllic rocks support the interpretation which maay of the plutons
represent the roots of volcanic centres. The host plutonic rock are the younger part of the Coast-No* Cascade plutonic belt md
the related early Tertiary Kamloops magmatic belt (Plafktr nod othera, 1989; Noldeberg and others, 1994~ 19flc). The
significant deposits in the bett are (table 4) (Noklebarg d others IWa, b, 1998): porphyry Mo &posits at Aja, Bell Moly
(Alice Arm), Kitsault (BC Moiy), Lucky Ship, Mamt Tho*, kcdbrrd, Roundy Creek, Serb Creek; potphyfy Cu-Mo
deposits at Berg, Big On~on, Dorothy, and NanikaPW, New Nanik); polymtalhc and AgpolymeWc vein deposits zit Capaxe
Lake, Equity Silver (Sam Goosly), Nadina (Silver Queen), and Prbepesity-Porter Idaho; and porpbm Gu-Au (Mo) CitqW~Bsu
Bell Copper (Newman), Graaisle, and Morrison. However the age of the Equity Silver (Sam Goosly) depsit is unrwioid,