USGS Professional Paper 1697 - Alaska Resources Library

2000). The spatial location of the belt, about 200 km west of the
eastern limit of Cordilleran 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 Bayonne,
Cassiar, Tombstone, and Whitehorse belts (fig. 62; tables 3, 4).
Two other interpretations for the origin of the Omineca-Selwyn
plutonic belt and related metallogenic belts are (1) formation during
A-type subduction of the miogeocline and transtensional
tectonics (Woodsworth and others, 1991, or (2) formation in
the rear of a single broad, mid-Cretaceous, Cordillera-wide, subduction-related
arc (Armstrong, 1988).
Tombstone Metallogenic Belt of Ag Polymetallic
Vein, Au-Sb Vein, and W-Sn-Au and Cu-Au Skarn
Deposits, Central Yukon Territory (Belt TS)
The Tombstone metallogenic belt of Ag polymetallic vein,
Au-Sb vein, and W-Sn-Au and Cu skarn deposits (fig. 62; tables
3, 4) occurs in the central Yukon Territory and is associated with
1
2
Lower Schist
Central Quartzite
Upper Schist
Vein fault
Ore deposit
Cross fault
Contact
3
4
5
6
7
8
Late Early Cretaceous Metallogenic Belts (120 to 100 Ma; figs. 61, 62) 171
10
9
Galena Hill
25°
12
11
Ore Deposits
1. Silver King
2. Husky S.W.
3. Husky
4. Elsa 17 Vein
5. Elsa
6. Dixie
7. No Cash
8. Ruby
late Early Cretaceous mafic to intermediate, alkalic plutons
of the Tombstone Plutonic Suite, which occurs in the Tombstone
and Syenite Ranges of the northwestern Yukon Territory
(Woodsworth and others, 1991; Mortensen and others, 1994).
The belt contains major Ag polymetallic vein deposits at Keno
Hill (Galena Hill), Craig (Tara, Nadaleen Mountain), and
Rusty Mountain (Vera, Val, Cavey), a Sb-Au vein at Brewery
Creek (Loki Gold), and a W skarn deposit at Ray Gulch
(Potato Hills, Mar; table 4) (Nokleberg and others 1997a,b,
1998). An exploration model for intrusion-related Au systems
has been developed from the Tombstone Plutonic Suite by
Lang and others (2000).
Keno Hill-Galena Hill District of Ag Polymetallic Vein
Deposits
The Keno Hill-Galena Hill district of Ag polymetallic
vein deposits (fig. 77) consists of argentiferous galena,
freibergite, and pyrargyrite with minor polybasite, stephanite,
argentite, and native silver that occur in fault veins,
breccias, and sheeted zones (Watson, 1986; Lynch, 1989;
Murphy and Roots, 1992; Yukon Minfile, 1992). The deposit
is hosted predominantly within the Keno Hill Quartzite of
the Early Mississippian Upper Earn Group, which forms part
of a Devonian and Mississippian clastic wedge in the North
American Craton Margin. Two stages of veining occur—an
earlier stage of quartz-pyrite-arsenopyrite-sulphosalts and
13
14
16
15
17
18
9. Bermingham
10. Townsite
11. Hector-Calumet
12. Miller
13. Galkeno
14. Onek
15. Bellekeno
16. Sadie Ladue
19 20
22
21
Keno Hill
25°
0 4 km
Mount Hinton
17. Lucky Queen
18. Shamrock
19. Keno 18 Vein
20 Keno
21. Porcupine
22. Comstock
Figure 77. Keno Hill (Galena Hill) Ag polymetallic vein deposit, Tombstone metallogenic belt, Canadian Cordillera.
Schematic regional geologic map showing locations of major deposits. Adapted from Watson (1986). See
figure 62 and table 4 for location.