Metallogenesis and Tectonics of the Russian Far East, Alaska, and ...

Mississippian age of mineralizalioi~ (MINFILE, 2002). Massive stratabound Ba deposits, which occur in the same region at
Muncho Lake, northern British Columbia, are no& hosted by the sam strata, and may be spatially related to fluorite-free barite
replacements and breccias. The Muncho Lake Ba deposit in northern British Columbia consists of mssive, stratabound barite
which is devoid of fluorite. The barite layer overlies the Waknash Formatoin and is bedded and contains local abundant sandstone,
and may exhibit evaporite textures (Dan Hora, writlen commun., 2000). A h bccurring in the area area barite veins (Butnerchuk
and Hancock, 1997; MINFILE, 2002).
Origin of and Tectonic Setting hr
Liard Metallogenic Belt
The Liard metallogenic belt of !hutbeast Missouri(?) 3214 deposits is hosted in Devonian passive contineatal margin
sedimentary rocks of the N oh American Craton Margin. The dtpdsits exhibit characteristics similar to Southeast Missouri Pb-Zn
deposits in the Robb Lake metallogebic belt of Southeast M i m i Pb-Zn deposits (described herein), and to the Gatagzt
metallogenic belt of SEDEX deposit (described herein). Sulpbur isotope analyses exhibit beavy values for barite sulfur in (111 thne
metallogenic belts (K.M. Dawson, unpublished data, 1995). These data and a similar geologic setting suggest a gmetic retation
between the two deposit types and Lhree metallogenic belh A rimih rifling origin is interpreted kr all three metahgenic belts.
The rifting is interpreted as occurring duriag the Lete Devonian a d Early Mississippian rifling event when the Yukon-Tanana and
Kootenay metamorphosed continental margin rerraaes seperakd hom ha North hmican Cmbn Margin (NoMeberg and ot6~118,
1994c, 1997c, 2000; Monger and Nokieberg, 1996). During the rifhg, volcanism, plutonism, related hydrothermal activity, and
sedimentary exhalations occmd in the North American Craton Margin ond in the Yukon-Tanana and Kootsnay ~~ (Paradis
and others, 1998).
Gataga Metallogenic Belt of Zn-Pb-Ag-Ba
SEDEX Deposits (Belt GA)
Northern British Columbia
The Gataga metallogenic belt of Zn-Pb-Ag-Ba SGDEX deposits (fig. 17; tables 3,4) occurs in mmtem British
Columbia. The deposits are hosted in basbid sedhenuuy strlta of h Kechilca Trough, a suutbeastera extension of Selwyn Basin
(Fritz and others, 199 1). The belt contaiar eight significant dapasiB and extends for 180 krn southmard from L)Olltpik Creek to
Akie River. The deposits are localized in inf'd euxinic sub-basins in a structurally controlled trough which was p dy flanked
by carbonate reefs (MacIntyre, 1982, 1998). The si.pificant dqmib arc at Akie, Cirque (Stromay), and Driftpile Creek (Saint,
Roen; table 4) (Nokleberg and otkers 1997% b, 1998). The deposils and bost rocks are part of a sequence of Late Devonian
(Famennian) turbiditic shale and cherty argillite of the E m Group (Pigagc, 1986; Paradis and others, 1998).
Cirque (Stronsay) Deposit
The Cirque (Stromy) Zn-Pb-Ag-Ba SEDEX deposit (fig. 28), tkt largest in the Gataga belt, mxwjsts of sbtifona,
laminar banded, massive berite with pyrite, galena and sphalerite which occur in twbidite $Me, chert, and cherty argillite of the
Late Devonian Gunstee1 Formation (Jefferson and others, 1983; Gorzynski, 1986). The host rocks are s~licxous and contacts
between sulfide bodies and sadimmb are 3barp. Tbc deposit forms a 100 by 300 m taping, wedgeshaped Iw whicb is about
10 to 60 m thick. The Cirque and adjacent South Cirque &posits contain estimated reserves of 52.2 million tonnes pading 8% Zn,
2% Pb, and 47 g/t Ag (Mining Review, 1992).
Driftpile Creek SEDEX
Zn-Pb-Ag-Ba Deposit.
The three sulfide bodies at the Driflpile SEDEX Zn-%Ag-Ba deposit consist of stratifarm Ryritc, sphaleribe, galene, and
barite in siliceous black turbiditic shale of Famian (Late Devonian) age ( Pds and others, 1998). The deposit has estimated
reserves of 18.1 million tonnes grading 2.38% Zn+Pb (bley, 1991; Pmdis and others, 1995). The sulfide bodies wcut in three
stratigraphic levels in the Gunsteel Formation of the Earn Assemblage in different thrust-bounded pantIs. The host &ntary
rocks are interpreted as part of a Devonian-Mississippian elastic wedge.
Origin of and Tectonic Setting for
Gataga Metallogenic Belt
The SEDEX Zn-PbAg-Ba deposits of the Gataga metallogenic beh are interpreted as forming during deposition of
basinal clastic rocks of the Earn Asscmbhge during tbe early to lak Famennim over a time span of not more than 7 million years.
This relatively brief episode occuated during or immediately after a period afcontinental-margin arc fo~tion and subsequent
rifting of the North American Craton Margin in the early Mississippian (Paradis and otbers, 1998). The rifting is interpreted to
have influenced sedimentailon and volcanism in the Yukon-Tanma and Kootenay terranes (Nokleberg and otbers. 1994c, 1997~;