USGS Professional Paper 1697 - Alaska Resources Library

The Emerald deposit has produced approximately 7,416 tonnes
of Mo-W concentrate. The Pb-Zn deposits at the nearby Jersey
and Emerald mines are interpreted as distal skarns relative to the
W skarn; however, others have interpreted the Pb-Zn deposits as
syngenetic (Dawson, 1996a).
Phoenix-Greenwood Cu Deposit
The Phoenix-Greenwood Cu-Au skarn deposit consists
of chalcopyrite, pyrite, pyrrhotite, and magnetite plus minor
sphalerite and galena that occur in a garnet-rich calc-silicate
skarn assemblage of andradite, clinozoisite, diopside and quartz
(Church, 1986; Schroeter and Lane, 1991; MINFILE, 2002).
The skarn hosted by Triassic carbonate, clastic, and volcanic
rocks of the previously accreted Quesnellia terrane in proximity
to contacts with Middle Jurassic and mid-Cretaceous granitoid
intrusive rocks. Production from 1893 to 1985 was 270,000
tonnes Cu, 36 tonnes Au, and 117 tonnes Ag. The deposit age is
interpreted as Middle Jurassic to Early Cretaceous.
Mineral King Zn-Pb-Ag Skarn and Manto Deposit
The Mineral King deposit consists of sphalerite, galena,
and pyrite with bournonite and rare meneghinite that occur in
steeply dipping pipes or as manto-style replacements along
steeply dipping shear zones associated with a synclinal wedge
between two faults. The deposit is hosted in the Middle
Proterozoic Mount Nelson Formation composed of dolomite
and dolomitic quartzite. The mine at the deposit produced an
estimated 2.1 million tonnes grading 4.12 percent Zn, 1.70
percent Pb, and 24.8 g/t Ag (Fyles, 1960). Estimated current
reserves are 72,576 tonnes grading 34.3 g/t Ag, 2.5 percent
Pb, and 4.5 percent Zn.. No intrusive rock is exposed, but
the deposit is interpreted as a Zn-Pb skarn and manto distally
related to a buried intrusion (Dawson and others, 1991) of the
Bayonne Plutonic Suite.
Origin of and Tectonic Controls for Bayonne
Metallogenic Belt
The Bayonne metallogenic belt is hosted in the extreme,
southern part of the Omineca-Selwyn plutonic belt (fig. 62).
The lithophile geochemistry of the plutonic suite is reflected
in the abundance of porphyry Mo and related skarn deposits.
The Omineca-Selwyn plutonic belt extends from the southern
part of the Canadian Cordillera, across Interior Alaska, and
northwestward into the Russian northeast and consists chiefly
of granodiorite, granite, quartz syenite, and minor syenite plutons
of Early to mid-Cretaceous age (110-90 Ma; Monger and Nokleberg,
1996; Nokleberg and others, 1994c; 2000). The plutons in
the belt form an extensive linear array of discrete intrusions, and
many plutons exhibit S-type character. Extrusive equivalents
(such as the South Fork Volcanics in the Yukon Territory) are rare.
The plutons commonly have high initial strontium ratios (about
0.710), indicating partial derivation from old cratonic crust (Armstrong,
1988: Woodsworth and others, 1991). The spatial location
of the belt, about 200 km west of the eastern limit of Cordilleran
Early Late Cretaceous Metallogenic Belts (100 to 84 Ma; figs. 79, 80) 177
deformation, and chemistry suggests an anatectic origin of partial
melting of cratonic crust during thickening caused by Cretaceous
contraction (Monger and Nokleberg, 1996; Nokleberg and others,
2000) that was associated with orthogonal convergence
between the Farallon oceanic plate and North America (Englebretson
and others, 1985; 1992) and subsequent regional
extension (Pavlis and others, 1993). Other metallogenic belts
of granitic-magmatism-related deposits hosted in the Omineca-
Selwyn plutonic belt in the Canadian Cordillera, Alaska, and the
Russian Northeast include the Cassiar, Selwyn, Tombstone, and
Whitehorse belts (fig. 62; table 3).
Early Late Cretaceous Metallogenic
Belts (100 to 84 Ma; figs. 79, 80)
Overview
The major early Late Cretaceous metallogenic belts in
the Russian Far East, Alaska, and the Canadian Cordillera are
summarized in table 3 and portrayed on figures 79 and 80. The
major belts are as follows: (1) In the Russian Southeast, the
Kema (KM), Lower Amur (LA), Luzhkinsky (LZ), Sergeevka
(SG), and Taukha (TK) belts, which contain a large array of
granitic-magmatism-related deposits, are hosted in or near the
East Sikhote-Aline volcanic-plutonic belt and are interpreted
as forming during subduction-related granitic plutonism that
formed the East Sikhote-Aline continental-margin arc. (2) In the
same region was the Aniva-Navil (ANN) metallogenic belt of
volcanogenic Mn and Fe and Cyprus massive sulfide deposits
that are interpreted as forming in guyots and oceanic crustal
and island-arc assemblages that were subsequently tectonically
incorporated into the Aniva and Nabilsky terranes accretionary-wedge
and subduction-zone terranes. (3) Also in the same
region, continuing on from the late Early Cretaceous was the
Badzhal-Ezop-Khingan (BZ-KH) belt of granitic-magmatismrelated
deposits, which is hosted in the Khingan-Okhotsk volcanic-plutonic
belt, and is interpreted as forming in the Khingan
continental-margin arc. (4) In the Russian Northeast are the
Chaun (CN), Dogdo-Erikit (DE), Korkodon-Nayakhan (KN),
Koni-Yablon (KY), Okhotsk (OH), Omsukchan (OM), and
Verkhne–Kolyma (VK) zones, which constitute various parts
of the Eastern Asia belt. In the same region and also part of the
are the Eastern Asia metallogenic belt are the Adycha-Taryn
(AT), Chokurdak (CD), and Vostochno-Verkhoyansk (VV)
belts. These zones and belts all contain a rich array of graniticmagmatism-related
deposits, which are interpreted as forming
during subduction-related granitic plutonism, which formed
the Okhotsk-Chukotka continental-margin arc. The Eastern
Asia metallogenic belt of granitic-magmatism-related deposits
contains a complex array of zones (fig. 79, table 3). Each zone
contains a characteristic suite of mineral deposit types that are
herein interpreted as reflecting the underlying terranes through
that the granitic magmas ascended. (5) On northern Kamchatka