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

Origin of and Tectonic Controls for
Prince of Wales lsland Metallogenic Belt
The continental-margin arc-related deposits deposits of the Prince of Wales Island metallogenic belt are mainly hosted in
Orodovician and Silurian granitoid rocks which intrude early Paleozoic stratified rocks of the Alexander sequence of the
Wrangellia superterrane (Nokleberg and others, 1995a). The stratified rocks consist of felsic to mafic volcanic and associated
marine sedimentary rocks. The known porphyry Cu and associated deposits occur in plutons which range from 472 to 432 Ma in
age (Turner and others; 1977; Herreid and others, 1978; Eberlein and others, 1983; Gehrels, 1992; Gehrels and Berg, 1992). The
zoned mafic-ultramafic Salt Chuck deposit, one of a series of mafic-ultramafic bodies intruding the Descon Formation (Loney and
Himmelberg, 1992), has a K-Ar isotopic age of 429 Ma (Loney and others, 1987). This suite of deposits and host rocks are
interpreted as forming during Ordovician and Silurian, subduction-related, island-arc magmatism in the Alexander sequence of the
Wrangellia superterrane (Gehrels and Berg, 1994; Nokleberg and others, 1994c, 1995a, 1997c, Goldfarb, 1997). The granitoid
plutons and associated plutons are herein interpreted as forming at intermediate levels of the arc, whereas the Salt Chuck zoned-
mafic-ultramafic deposit is herein interpreted as forming from magmas which intmded into the deeper levels of the arc.
Middle and Late Devonian
Metallogenic Belts
(387 to 360 Ma; Figures 16, 17)
Overview
The major Middle and Late Devonian metallogenic belts in the Russian Far East, Alaska, and the Canadian Cordillera are
summarized in table 3 and portrayed on figures 16 and 17. The major belts are as follows. (1) In the Russian Southeast, the
Yaroslavka (YA) belt, which contains F and Sn greisen deposits, is hosted in the Khanka continental-margin arc terrane. The belt
is interpreted as fonning during anatectic granitic plutonism which occurred during terrane accretion. (2) In the Russian Northeast,
Northern Alaska, and the Canadian Cordillera, the Arctic (AT), Brooks Range (BR), Dawson (DA) Frances Lake (FR), Kedon
(KE), Kootenay-Shuswap (KS), and Tracy (TR) belts contain deposits associated with felsic to mafic marine volcanism or with
granitic magmatism. These belts are hosted in the North Asian or North American Cratons or Craton Margins, or in cratonal or
continental-margin (arc) terranes which were derived from those craton margins. These belts are interpreted to be associated with
formation of a short-lived continental-margin arc (Kedon arc in the Russian Northeast) along the margin of the North Asian
Craton and Craton Margin and the North American Craton Margin. And (3) in Southern Alaska and the Canadian Cordillera, the
Mount Sicker belt, which contains kuroko massive sulfide deposits, is hosted in the Wrangellia island-arc superterrane. This belt is
interpreted as forming during subduction-related volcanism in the short-lived Sicker island arc.
In the Russian Northeast, Alaska, and Canadian Cordillera, the Berezovka River (BE), Cathedral (CA), Dempster (DE),
Finlayson Lake (FL); Gataga (GA), Ingenika (IN), Liard (LI), Northern Cordillera (NCO), Macmillan Pass (MP), older pan of
Mystic (MY), Robb Lake (RL), Selennyakh River (SEL), Sette-Daban (SD), Southern Rocky Mountain (SRM), Tornmot River
(TO), Urultun and Sudar Rivers (URS), and Yarkhodon (YR) belts. which contain massive sulfide, bedded barite, carbonatite-
related Nb, Ta, and REE, and related deposits, are hosted either in the North Asian or North American Craton Margins, or in
passive continental margin terranes derived from those craton margins. These belts are interpreted as forming during late Late
Devonian and (or) Early Mississippian rifting of either the North Asian or the North American Craton Margins (table 3), or during
generation of low-temperature brines from adajacent shale basins. In the below descriptions of metallogenic belts, a few of the
noteable or significant lode deposits (table 4) are described for each belt.
Metallogenic-Tectonic Model for
Middle through Late Devonian
(387 to 360 Ma; Figure 18)
During the Middle to Late Devonian (387 to 360 Ma), the major metallogenic-tectonic events were (fig. 18; table 3): (I)
formation of a discontinuous continental-margin arc (Kedon arc in Russian Northeast) and contained metallogenic belts, and
associated subduction zone along the North Asian and North American Craton Margins; (2) in the late Late Devonian, inception
of rifting of the North Asian and North American Cratons and Craton Margins, resulting in formation of new terranes and
associated metallogenic belts (table 3); and (3) formation of the Sicker arc and contained metallogenic belts, and associated
subduction zone in the Wrangellia superterrane. Sedimentation continued along the North Asian and North American Craton
Margins. Out of the field of view of figure 18 was formation of the Yaroslavka (YA) belt which contains F and Sn greisen
deposits. The belt is hosted in the Voznesenka terrane in the Khanka continental-margin arc superterrane and is interpreted as
forming during anatectic granitic plutonism which occurred during accretion of the Voznesenka terrane with other parts of the
Khanka superterrane in the early Paleozoic.