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

crosscuts graywacke and siltstone adjacent to a contact with a porphyritic quartz monzonite stock. Estimated combined production
and reserves are 1.9 million tonnes grading 29.5 g/t Au (Rhys and Godwin, 1992; Rhys and others, 1995). The Red Mountain
deposit (Brown and Kahlert, 1995) consists of a semi-tabular stockwork of pyrite-pyrrhotite which contains high Au and Ag
values (up to 20 g/t Au), disseminated sphalerite-pyrrhotite mineralization, and intense sericite alteration. The deposit occurs
above a quartz-molybdenite stockwork at the top of a Early Jurassic monzodiorite and quartz monzodiorite stock and sill which
intrude sedimentary and volcanic rocks of the Triassic Stuhini Group and the Early and Middle Jurassic Hazelton Group.
Estimated resources at Red Mountain are 2.5 million tonnes of 12.8 g/t Au and 38.1 g/t Ag (Rhys and others, 1995).
The Silbak Premier Au-Ag-Pb-Zn epithermal vein deposit is hosted by volcanic and volcaniclastic rocks of the Hazelton
Assemblage. The deposit consists of argenlite and electrum which occur both in low-sulfide and base-metal sulfide ore. The veins
are related to subvolcanic, quartz-K-feldspar porphyry dikes which form part of the Texas Creek plutonic suite. Between 19 18 and
1987, about 56.1 tonnes of Au and 1,270 tonnes of Ag were produced. Estimated reserves are 6.1 million tonnes grading 2.33 glt
Au and 90.5 g/t Ag (Alldrick and others, 1987).
Polaris Au Quartz Vein Deposit
The Polaris Au quartz vein deposit consists of native gold associated with arsenopyrite and stibnite in quartz-ankerite
veins (Marriott, 1992; Mihalynuk and Marriott, 1992). The deposit has produced approximately 231,000 oz Au from 760,000 tons
of ore, with a recovered grade of 0.30 oz Ault. The deposit contains estimated resources of 2.196 million tonnes grading 14.74 g/t
Au. The deposit is underlain by late Paleozoic to Triassic Stuhini Group volcanic and sedimentary rocks. The volcanic rocks
composed of andesite and basalt flows and pyroclastic rocks host gold in an assemblage of arsenopyrite, ankerite, sericite, pyrite,
fuchsite, and stibnite. The structures hosting the deposit are splays of the Tulsequah River shear zone.
Muddy Lake Au Quartz Vein Deposit
The Muddy Lake (Golden Bear, Totem) Au quartz vein deposit consists of disseminations and fracture-fillings of
extremely fine-grained pyrite which occur along fault contacts of tuffite and limestone (Melis and Clifford, 1987; Osatenko and
Britton, 1987; Schroeter, 1987; Dawson and others, 199 1; North American Metals Corp, news release, February 1995). The
deposit contains estimated reserves of 720,000 tonnes grading 5.75 g/t Au. The deposit has been interpreted as a mesothermal Au-
quartz veins hosted by silicified limestone, dolostone and tuff of the Permian Asitka Assemblage, and mineralization is probably
related to an unexposed pluton of the Texas Creek suite. The deposit occurs in a north-trending, 20-km-long fault zone. Four
deposits occur on the property at Bear, Fleece, Totem, and Kodiak. Recent studies interpret the deposit as a Carlin-type deposit
(Poulsen, 1996; Lefebure and others, 1999), which contains both oxidized and primary ore.
Origin of and Tectonic Controls for
Texas Creek Metallogenic Belt
The Texas Creek metallogenic belt occurs in a suite of dominantly calc-alkaline granitoid, but in part, gabbroic and
alkalic, plutons which intruded mainly in the Early Jurassic as part of the Stikinia arc and the flanking Cache Creek subduction-
zone terrane, prior to accretion to North America in the Middle Jurassic (Dawson and others, 1991; Kirkham and Margolis, 1995;
Mihalynuk and others, 1994; Monger and Nokleberg, 1996; Nokleberg and others, 2000). The Stikinia island-arc terrane is
interpreted as forming on the deformed continental margin strata of Yukon-Tanana terrane which is interpreted as a rifted
fragment of the North American Craton Margin (Gehrels and others, 1990; Monger and Nokleberg, 1996; Nokleberg and others,
1994c, 1997c; 2000). Several metallogenic belts formed during granitic magmatism associated with formation of the Stikinia and
Quesnellia island arcs. The metallogenic belts which formed in conjunction with the Stikinia island arc are the Copper Mountain
(North), Galore Creek, Guichon, Klotassin, Texas Creek, and Toodoggone belts. The Copper Mountain (South) and Guichon
metallogenic belts formed in conjunction with the Quesnellia island arc.
Early Jurassic Metallogenic Belts
(208 to 193 Ma; Figure 42)
Qvewiew
The major Early Jurassic metallogenic belts in Alaska and the Canadian Cordillera are summarized in table 3 and
portrayed on figure 40. No major Early Jurassic metallogenic belts existed in the Russian Far East. The major belts in Alaska and
the Canadian Cordillera are as follows. (1) Three belts are hosted in the Wrangellia island-arc superterrane These belts are the
Talkeetna Mountains-Alaska Range belt (TM), which contains kuroko massive sulfide deposits, the Alaska Peninsula (AP) belt,
which contains granitic magmatism deposits, and the Island Porphyry (IP) belt, which contains granitic-magmatism-related
deposits,. These belts are interpreted as forming in the Talkeetna-Bonzana arc preserved in the Wrangellia superterrane. (2) In the
Canadian Cordillera, continuing on from the Late Triassic, commencing in the Early Jurassic were the Coast Mountains (CM),
Copper Mountain (North; CMN), Copper Mountain (South; CMS), Galore (GL), Guichon (GU), Klotassin (KL), and Texas Creek