USGS Professional Paper 1697 - Alaska Resources Library

Clark Range Metallogenic Belt of Sediment-
Hosted Cu-Ag Deposits, Southern British
Columbia (Belt CR)
The Clark Range metallogenic belt of sediment-hosted
Cu-Ag deposits occurs in the Clark Range of southeastern
British Columbia and southwestern Alberta (fig. 3; tables 3,
4) (Nokleberg and others, 1997b, 1998). The belt is hosted in
the predominantly clastic rocks of the Appekuny, Grinnell, and
Siyeh Formations of the lower Purcell Supergroup, which was
deposited along the passive continental margin of the North
American Craton. The metallogenic belt contain numerous,
minor occurrences of sediment-hosted Cu-Ag and less common
Zn-Pb-Cu deposits (Kirkham, 1974; Morton and others,
1974; Collins and Smith, 1977; Binda and others, 1989). The
sedimentary rocks of the Mesoproterozoic Purcell Supergroup
comprise a dominantly passive margin depositional sequence
of fine-grained, basinal clastic rocks at least 11 km thick. They
thin eastward into platformal sedimentary rocks toward the
North American Craton. The supergroup is correlated with the
Belt Supergroup in the western and northern United States.
The metallogenic belt contains no significant mineral deposits
(Nokleberg and others, 1997a,b).
Clark Range Sediment-Hosted Cu-Ag Deposits
The sediment-hosted Cu-Ag sulfide occurrences in
the Clark Range metallogenic belt are most abundant in the
Grinnell Formation. The deposits typically consist of erratically
disseminated chalcocite, bornite, and less common Cu
sulfides that are hosted in relatively permeable white quartzarenite
interlayered with red argillite. Larger Canadian
occurrences include Kinshena Creek and Bull River and an
extensive occurrence in the Akamina syncline along the contact
between the Grinnell and Siyeh Formations (Binda and
others, 1989). None contain measured reserves or resources.
The Grinnell Formation is the stratigraphic equivalent of the
Revett Formation of Montana, which hosts the important
Spar Lake Cu (Ag) deposit (Hayes and others, 1989). In this
area is a 75-km-long belt of sediment-hosted Cu-Ag and Zn-
Pb occurrences that are located in the Spokane and Helena
Formations in the eastern Belt Basin of western Montana.
These units are the equivalents to the Siyeh Formation in
Canada (Lange and others, 1989).
Origin of and Tectonic Controls for Clark Range
Metallogenic Belt
The Clark Range metallogenic belt is hosted by sedimentary
rocks that are interpreted as part of Proterozoic
through middle Paleozoic passive margin along the North
American Craton (Nokleberg and others, 1994c, 1997b,c,
1998, 2000; Monger and others, 1996). The sediment-hosted
Cu occurrences in the Clark Range metallogenic belt, which
occur in quartz-arenite beds in dominantly red argillite, were
interpreted by Kirkham (1974) as forming during late diage-
Cambrian through Silurian Metallogenic Belts (570 to 408 Ma) 23
netic mineralization of eolian beds in a sabkha sequence. In
contrast, the occurrences are interpreted by Collins and Smith
(1977) as the product of cyclically controlled redox conditions
during short-lived, fluvial to lacustrine episodes. Alternatively,
Morton and others (1974) interpret the metal-bearing fluids
forming from exhalations along faults.
Deposition of a prograding wedge of Purcell (Belt)
sedimentary rocks is interpreted as the result of major Mesoproterozoic
rifting along the passive continental margin of
the North American Craton (Monger and others, 1972). A
rift-related, exhalative origin for the sediment-hosted copper
deposits in the Clark Range metallogenic belt is supported by
analogous, similar deposits elsewhere in the North American
Craton Margin (1) Cap Mountains deposit in the southern
Franklin Mountains, Northwest Territories (Aitken and others,
1973), (2) Churchill belt of Cu vein deposits, (3) Gillespie belt
of SEDEX deposits, and (4) the Purcell belt of SEDEX deposits.
Many of the metallogenic belts with SEDEX deposits are
directly associated with mafic volcanic rocks and hydrothermal
activity.
Cambrian Through Silurian
Metallogenic Belts (570 to 408 Ma)
Overview
The major Cambrian through Silurian metallogenic belts
in the Russian Far East, Alaska, and the Canadian Cordillera
are summarized in table 3 and portrayed on figures 2 and 3.
The major belts, although with disparate origins, are as follows
(1) In the Russian Southeast, Voznesenka (VZ) and the
Kabarga (KA) belts, which contain Korean Pb-Zn and Ironstone
(Superior Fe) deposits, are hosted in the Khanka continental-margin
arc superterranes. These belts are interpreted as
forming during marine sedimentation in rifted fragments of
the Gondwandaland supercontinent. (2) In the same region,
the South Khingan (SK), and Gar (GA) belts, which contain
ironstone (Superior Fe), volcanogenic Fe, Cu massive sulfide,
and stratiform Zn-Pb deposits, are hosted in the Bureya
or Khanka continental-margin arc superterranes. These belts
are interpreted as forming during early Paleozoic sedimentation
or marine volcanism in Manchurid and Altaid orogenic
systems. (3) In the central part of the Russian Far East, Galam
(GL) belts, Omulevka River (OR), Rassokha (RA), which
contain Volcanogenic Fe and Mn sedimentary, Austrian Alps
W, Kipushi Cu-Pb-Zn, and Basaltic Cu, sediment-hosted
Cu deposits, are interpreted as forming during early Paleozoic
sea-floor spreading, regional metamorphism, or during
subduction-related volcanism. (4) In the Russian Northeast,
Dzhardzhan River (DZR) belt, which contains Southeast
Missouri Pb-Zn, sediment-hosted Cu, and sandstone-hosted
U deposits, is interpreted as forming during incipient rifting
of early Paleozoic (Cambrian) continental-margin. (5) In the
Canadian Cordillera, the Anvil (AN), Howards Pass (HP),