USGS Professional Paper 1697 - Alaska Resources Library

74 Metallogenesis and Tectonics of the Russian Far East, Alaska, and the Canadian Cordillera
Origin of and Tectonic Controls for Northwestern Brooks
Range Metallogenic Belt
The Northwestern Brooks Range metallogenic belt of
Zn-Pb-Ag SEDEX, bedded barite, kuroko massive sulfide, and
vein deposits is hosted in a tectonically disrupted and strongly
folded assemblage of Mississippian and Pennsylvanian chert,
shale, limestone turbidite, minor tuff, and sparse intermediate
to silicic volcanic rocks, mainly keratophyre, named
the Kuna Formation by Mull and others (1982). The Kuna
Formation is the basal unit of the Kagvik sequence of Churkin
and others (1979) and the Kagvik terrane of Jones and others
(1987) and part of the DeLong Mountains terrane of the Arctic
0 100 m
Okpikruak Formation - shale > sandstone
(Cretaceous)
Otuk Formation - chert and shale (Triassic)
Siksikpuk Formation - shale and chert
(Permian and Pennsylvanian)
Barite and baritic ore (Pennsylvanian and
Mississippian)
Siliceous ore and silica rock (Pennsylvanian
& Mississippian)
Veined - siliceous
black shale
Calcareous black shale
Volcaniclastic rocks
Drill hole
Thrust fault
Contact
Alaska superterrane of Moore and others (1994). This unit
and younger late Paleozoic and early Mesozoic cherts and
shales are interpreted either as a deep-water, allochthonous
oceanic assemblage (Churkin and others, 1979; Nokleberg and
Winkler, 1982; Lange and others, 1985) or as an assemblage
deposited in an intracratonic basin (Mull and others, 1982;
Mayfield and others, 1983; Schmidt, 1997a). Herein, the
SEDEX Zn-Pb-Ag, bedded barite, and kuroko volcanogenic
massive sulfide deposits in the Northwestern Brooks Range
belt are interpreted as forming during a short-lived period of
Late Mississippian and Early Pennsylvanian rifting or backarc
spreading that was possibly associated with a short-lived
continental-margin arc.
S N
1,200
1,000
800
Kuna Formation
(Pennsylvanian
and Mississippian)
Median Ore Plate
Footwall
Median Plate
Waste Lower
Plate Ore
Plate
Figure 30. Red Dog Creek sedimentary exhalative Zn-Pb-barite deposit, Northwestern
Brooks Range metallogenic belt, northern Alaska. Schematic geologic cross section
through the Main deposit showing the structural interpretation of thrust plates and the
overturned fold related to thrust faults. Section along N 40 E. Adapted from Schmidt
(1997). See figure 17 and table 4 for location.