USGS Professional Paper 1697 - Alaska Resources Library

mentary rocks of the Cambrian to Devonian Nasina and Nisling
assemblages and equivalent rocks of the Yukon-Tanana terrane.
The assemblage consists of carbonaceous quartzite, quartz-mica
schist, marble, mafic and felsic metavolcanic rocks and lesser
amounts of metaplutonic rocks. Locally large parts of the terrane
occur in pendants and screens within plutons of the Coast
Plutonic Complex. These units are interpreted as part of the
extensive continental-margin igneous arc that formed along the
North American Craton Margin, prior to rifting of the Yukon-
Tanana and related terranes (Nokleberg and others, 1994c,
1997c). Remnants of the extensive middle Paleozoic Kootenay
continental margin arc and associated lode deposits extend for
several thousand km in various metamorphosed continental
margin terranes in Northern Alaska, East Central Alaska, the
northern Canadian Cordillera, and southeastern Alaska (Rubin
and others, 1991; Plafker and Berg, 1994; Nokleberg and others,
1994c, 1997c; Monger and Nokleberg, 1996; Nokleberg and others,
2000). Fragments of the Kootenay arc include several metallogenic
belts hosting the kuroko volcanogenic massive sulfide
and related deposits (Nokleberg and others, 1997a,b,c) (1) The
Arctic metallogenic belt in the Coldfoot terrane in Arctic Alaska,
(2) Alaska Range and Yukon-Tanana Upland metallogenic belt in
the Yukon-Tanana terrane in central and eastern Alaska, (3) the
Tracy metallogenic belt hosted in the Yukon-Tanana terrane in
southeastern Alaska and western British Columbia, (4) the Frances
Lake belt in the Yukon-Tanana terrane in the southern Yukon
Territory, and (5) the Kootenay-Shuswap belt in the Kootenay
terrane in the southern Canadian Cordillera and the Frances Lake
metallogenic belt in the southern Yukon Territories.
Mount Sicker Metallogenic Belt of Kuroko
Volcanogenic Massive Sulfide Zn-Cu-Pb-Au-Ag
Deposits (Belt MS) Vancouver Island
The Mount Sicker metallogenic belt of kuroko massive
sulfide Zn-Cu-Pb-Au-Ag deposits (fig 17; tables 3, 4) occurs in
0 40 m
Middle and Late Devonian Metallogenic Belts (387 to 360 Ma; figures 16, 17) 53
southwestern British Columbia on Vancouver Island. The belt is
hosted by the Late Devonian to Early Permian Sicker Group, a
sequence of arc-related volcanic and sedimentary strata in the
southern Alexander sequence of the Wrangellia superterrane.
The significant deposits are at Mount Sicker near Duncan
(Lenora-Tyee, Twin J, Lara, Copper Canyon), and Myra Falls
(Buttle Lake, Lynx, H-W, Battle; table 4) (Nokleberg and others
1997a,b, 1998).
Mount Sicker (Lenora-Tyee, Twin J, Lara, Copper Canyon)
Kuroko Massive Sulfide Zn-Cu-Pb-Au-Ag Deposit
The Mount Sicker (Lenora-Tyee, Twin J, Lara, Copper
Canyon) kuroko massive sulfide Zn-Cu-Pb-Au-Ag deposit
consists of massive pyrite, chalcopyrite, sphalerite, and
galena with barite hosted in Late Devonian felsic volcanic
tuffs of the McLaughlin Ridge Formation (Juras, 1987;
Sicker Group; Hoy, 1991; Robinson and others, 1994). The
combined estimated reserves and production for the Lenora-
Tyee-Twin J deposit are 594,852 tonnes grading 2.46 percent
Cu, 3.85 percent Zn, 0.37 percent Pb, 117.0 g/t Ag, and 2.5
g/t Au. Estimated reserves for the Lara deposit are 529,000
tonnes grading 1.01 percent Cu, 5.87 percent Zn, 1.22 percent
Pb, 100.1 g/t Ag, and 4.73 g/t Au. Estimated reserves for
the Copper Canyon deposit are 32.4 million tonnes grading
0.75 percent Cu, 8.57 g/t Ag, and 1.17 g/t Au (Dawson and
others, 1991).
Myra Falls (Buttle Lake, Myra, Lynx, H-W, Battle) Kuroko
Massive Sulfide Zn-Cu -Au-Ag Deposit
The Myra Falls (Lynx-Myra, Price, H-W, Battle) kuroko
volcanogenic massive sulfide Zn-Cu -Au-Ag deposit (fig. 24)
consists of massive sphalerite, chalcopyrite, pyrite and lesser
galena and barite with minor tennantite, bornite, pyrrhotite,
digenite, covellite and stromeyerite that occur in a number of
lenses along an east-west trend (Juras, 1987; Juras and Pear-
Hangingwall
(Lower Myra Fm.)
Footwall
(Price Fm.)
Quartz-feldspar phyric rhyolite:
Massive to in - situ brecciated
Hangingwall mafic sill:
Massive to in-situ brecciated
Zone of interaction between mafic
sill and felsic volcaniclastic debris
Massive to semimassive sulphide
Interbedded quartz-feldspar phyric
volcaniclastic beds and black mudstone
Footwall mafic volcanic rock
Contact
Fault
Figure 24. H-W kuroko massive sulphide Zn-Cu -Au-Ag deposit, Mount Sicker metallogenic belt, Canadian Cordillera. Schematic
cross section. Adapted from Barrett and Sherlock (1996b). See figure 17 and table 4 for location.