USGS Professional Paper 1697 - Alaska Resources Library

Red Rose W-Au-Cu-Ag Polymetallic Vein Deposit
The Red Rose W-Au-Cu-Ag polymetallic vein deposit
occurs near Hazelton, B.C. and consists of scheelite, ferberite,
chalcopyrite, molybdenite, and uraninite that occur in a
sheared quartz vein (EMR Canada, 1989; Dawson and others,
1991). The sheared quartz vein cuts one of three northeasttrending
diorite dikes that intrude contact metamorphosed
argillite and siltstone of the Red Rose Formation, near the
contact with porphyritic granodiorite of the Cretaceous Rocher
Deboule stock. Estimated reserves are 20,000 tonnes grading 5
percent WO 3 (Mulligan, 1984).
Capoose Lake Ag-Au Polymetallic Vein Deposit
The Capoose Lake Ag-Au polymetallic vein prospect
occurs 110 km southeast of Burns Lake in central British
Columbia and consists of Ag- and Au-bearing disseminations
and veinlets of galena, pyrite, pyrrhotite, chalcopyrite,
arsenopyrite, and sphalerite that are hosted in contact-metamorphosed
volcanic rocks of the Hazelton Group. The disseminations
and veinlets, which occur both as replacements of
garnet in the contact-metamorphosed host volcanic rocks and
as fillings in structurally controlled fracture zones, are related
to rhyolite sills that are coeval with and probably satellitic to
the adjacent Late Cretaceous Capoose batholith. Estimated
resources are 28.3 million tonnes grading 36 g/t Ag and 0.91
g/t Au (Andrew and Godwin, 1987; Andrew, 1988).
Nadina (Silver Queen) Ag Polymetallic Vein Deposit
The Nadina (Silver Queen) Ag polymetallic vein deposit
consists of sphalerite, galena, and chalcopyrite that occur in a
gangue of quartz, rhodochrosite, chalcedony, and barite that
are hosted in Late Cretaceous andesite and altered fragmental
volcanic rocks (EMR Canada, 1989; Leitch and others, 1990;
Dawson and others, 1991). Estimated reserves are 1.72 million
tonnes grading 6.19 percent Zn, 328 g/t Ag, and 2.7 g/t Au. The
deposit age is bracketed by microdiorite (with an isotopic age
of 75.0+1.0 Ma) (MINFILE, 2002) and by younger felsite dikes
and sills that are part of the Eocene Goosly Lake Intrusions.
Origin of and Tectonic Controls for Bulkey Metallogenic Belt
The Late Cretaceous Bulkley Plutonic Suite is coeval
with the Surprise Lake and Carmacks Plutonic Suites and with
the volcanic rocks of the Carmacks Assemblage, which all
occur in the northern part of the Stikinia terrane (Woodsworth
and others, 1991). Together, these plutonic rocks form part of
the extensive Late Cretaceous and early Tertiary Coast-North
Cascade plutonic belt that constitutes the major part of the
Coast continental-margin arc mainly in the western Canadian
Cordillera (Nokleberg and others, 1994c, 1997c; Monger
and Nokleberg, 1996). Local Late Cretaceous volcanic units
interpreted to be comagmatic with the Bulkley Plutonic Suite
include the Brian Boru (Sutherland Brown, 1960) and Tip
Top Hill (Woodsworth and others, 1991) volcanic rocks of the
Kagalka Group (MacIntyre, 1985).
Late Cretaceous and Early Tertiary Metallogenic Belts (84 to 52 Ma) (figs. 102, 103) 253
Fish Lake-Bralorne Metallogenic Belt of
Porphyry Cu-Mo, Porphyry Cu-Au, Au Quartz
Vein, Au-Ag Polymetallic Vein, and Related
Deposit Types (Belt FLB), Southwestern
British Columbia
The Fish Lake-Bralorne metallogenic belt of porphyry
Cu-Mo, Au quartz vein, and Au-Ag polymetallic vein deposits
(fig. 103; tables 3, 4) occur along the northeastern margin of the
Coast Plutonic Complex in southwestern British Columbia. The
belt contains the Bralorne district, which contains a group of
major Au mines. The Bralorne-and Pioneer Au deposits occur
in Permian and Triassic diorite, gabbro, and greenstone, part of
an ophiolite assemblage that occurs along a shear zone along the
complex tectonic boundary between Bridge River and Cadwallader
terranes. The Congress polymetallic vein and Minto Ag-Au
stibnite vein deposits in the Bridge River mining camp are
related to stocks and dikes of the early Tertiary Bendor suite with
isotopic ages of 70 to 65 Ma (Leitch and others, 1989; Church,
1995). These deposits occur to the northeast of the Bralorne
district. Several other Sb-Au polymetallic vein deposits occur
in the mining camp and are associated with the Late Cretaceous
and early Tertiary Bendor pluton, Robson stock, and related
intrusions (Leitch and others, 1989). Also occurring in the belt
are porphyry Cu deposits, as at Empress, which locally grade to
high-sulphidation epithermal vein systems in the easternmost
partr of the Coast Plutonic Complex, directly on strike from the
coeval Bralorne deposit (McMillan, 1983). The belt also includes
porphyry Mo and Cu-Mo occurrences that are associated with
Eocene stocks that occur along major dextral strike-slip faults.
The porphyry Cu-Mo and related deposits in the metallogenic
belt are associated with Late Cretaceous porphyry dikes
and stocks that are coeval with the adjacent eastern margin
of the Coast Plutonic Complex and intrude metasedimentary
rocks of the Methow terrane (Leitch and others, 1989). These
granitoid rocks are part of the extensive Late Cretaceous and
early Tertiary Coast-North Cascade plutonic belt, which occurs
along the western and central parts of the Canadian Cordillera
for several thousand km (Nokleberg and others, 1994c, 1997c;
Monger and Nokleberg, 1996). The significant deposits in the
belt are (table 4) (Nokleberg and others 1997a,b, 1998) (1)
porphyry Cu-Mo deposits at Fish Lake, Giant Copper (Canam,
A.M.), and Poison Mountain (Copper Giant), and (2) Au
quartz vein deposits at Bralorne, Pioneer (Bridge River area),
and Carolin. The Maggie (Bonaparte River) deposit occurs
along the margin of the belt.
Bralorne and Pioneer Au Quartz Vein Deposits
The Bralorne and Pioneer mines of the Bralorne district,
and the smaller Wayside and BRX mines, are typically large,
continuous, mesothermal Au-quartz-sulfide veins that range
from 1 to 2 m wide and consist commonly of quartz, calcite,
free gold, arsenopyrite, pyrite, and lesser sphalerite, galena,
scheelite, chalcopyrite and molybdenite (Leitch and others,
1989). The veins are lenticular and plunge steeply within a