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USGS Professional Paper 1697 - Alaska Resources Library

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margin of the North American Craton Margin (NAM). The<br />

relative positions of the two cratons (NSC, NAC) and their<br />

craton margin units (NSC, NSV, KN, NAM) are determined<br />

from paleomagtic data for the cratons (see Nokleberg and others,<br />

2000). In the North Asian Craton Margin and outboard terranes,<br />

the arc is preserved today in (1) sporadic occurrences of<br />

marine and continental volcanic and associated rocks and subduction-related<br />

granitic rocks in the southern part of the craton<br />

margin (NSV), (2) units that overlie parts of the Okhotsk<br />

(OK), Akekova (AK), Omolon (OM) cratonal terranes, (3) the<br />

Oloy (OL) and Yarakvaam (YA) island-arc terranes, and (4)<br />

the Beryozovka (BE) turbidite-basin terrane. Associated with<br />

this arc was the subduction of the older part of the Galam (GL)<br />

accretionary-wedge terrane along the margin of the North<br />

Asian Craton and Craton Margin (NSC, NSV), and subduction<br />

of the Angayucham and ancestral Pacific Oceans along the<br />

margin of the North American Craton Margin (NAM). Forming<br />

in part of the North Asian Craton Margin, from which the<br />

Omolon terrane was rifted, was the Kedon metallogenic belt<br />

168<br />

168<br />

156<br />

PW<br />

144<br />

156<br />

132<br />

52<br />

72<br />

56<br />

Middle and Late Devonian Metallogenic Belts (387 to 360 Ma; figures 16, 17) 39<br />

144<br />

that contains deposits related to felsic to mafic marine volcanism<br />

or to granitic magmatism in the Kedon arc.<br />

In the <strong>Alaska</strong> and the Canadian Cordillera, the arc is<br />

preserved today in sporadic occurrences of marine volcanic and<br />

associated rocks and shallow- to deep-level subduction-related<br />

granitic rocks in various parts of the Arctic <strong>Alaska</strong> (AA), Coldfoot<br />

(CO), Ruby (RB), Seward (SD), Yukon-Tanana (YT), and<br />

Kootenay (KO) terranes. Occurring in this arc, now preserved<br />

in various continental-margin terranes, were the Arctic (AT),<br />

Brooks Range (BR), Dawson (DA), Frances Lake (FR), Kootenay-Shuswap<br />

(KS), and Tracy (TR) metallogenic belts, which<br />

contain deposits related to felsic to mafic marine volcanism or to<br />

granitic magmatism. The Devonian arc is interpreted as extending<br />

discontinuously from Arctic <strong>Alaska</strong> to northern California<br />

(Rubin and others, 1991; Mortensen, 1992; Smith and Gehrels,<br />

1992; Nokleberg and others, 1994a; Plafker and Berg, 1994).<br />

(3) In the late Late Devonian, rifting of the North Asian<br />

and North American Cratons and Craton Margins occurred.<br />

Derived from the North Asian Craton (NSC) and Craton<br />

NAC<br />

CO<br />

AG<br />

CO<br />

SD<br />

RB<br />

NAC<br />

RB<br />

YO<br />

YT<br />

CC<br />

SD<br />

AG<br />

NX<br />

AG<br />

DL,<br />

MY<br />

YT<br />

AX<br />

AX<br />

WR<br />

AX<br />

BR WA<br />

OF<br />

PR<br />

PR SZ<br />

BA<br />

HO<br />

JF<br />

AG<br />

MIDDLE DEVONIAN TO GA - Gataga<br />

MISSISSIPPIAN<br />

IN - Ingenika<br />

METALLOGENIC BELTS KS - Kootenay-Shuswap<br />

Arctic<br />

Ocean<br />

AKY - <strong>Alaska</strong> Range &<br />

Yukon-Tanana Upland<br />

AT - Arctic<br />

BR - Brooks Range<br />

LI - Liard<br />

MP - Macmillan Pass<br />

MS - Mount Sicker<br />

MY - Mystic<br />

CA - Cathedral<br />

NBR - Northwestern<br />

BR<br />

DA - Dawson<br />

Brooks Range<br />

AA<br />

DE - Dempster<br />

NCO - Northern Cordillera<br />

oa<br />

BR<br />

ES - Eastern Seward RL - Robb Lake<br />

NAM<br />

Peninsula<br />

SRM - Southern Rocky<br />

BR<br />

PC<br />

NBR AA<br />

FL - Finlayson Lake Mountain<br />

AG AG<br />

NCO<br />

WS<br />

NAM FR - Frances Lake TR - Tracy<br />

AT<br />

YT<br />

DE MP<br />

NCO LI<br />

FI<br />

ES<br />

AKY SV YT<br />

FR<br />

RL<br />

DA<br />

SM<br />

QN<br />

ST<br />

KY<br />

oa YT<br />

GA<br />

CA<br />

oa<br />

AKY WR<br />

SM<br />

AX oa<br />

CA IN<br />

SRM<br />

MO<br />

TR<br />

CG<br />

ST<br />

TR<br />

KO<br />

KY<br />

oa<br />

NAM<br />

CG<br />

TR<br />

CC<br />

oa KI<br />

YT<br />

KS QN<br />

CD MT<br />

PW YAK<br />

MT<br />

MY<br />

oa<br />

oa<br />

TR<br />

CG<br />

CR<br />

oa NY<br />

PE<br />

MS<br />

GD<br />

TG<br />

PW<br />

WR<br />

PAC<br />

oa<br />

PE<br />

IZ<br />

CG<br />

OC<br />

oa<br />

CG<br />

Pacific<br />

Ocean<br />

64<br />

48<br />

0<br />

132<br />

56<br />

Eastern limit of<br />

JFR<br />

Cordilleran mation<br />

800 km<br />

defor<br />

0 800 mi<br />

Figure 17. Generalized map of major Middle and Late Devonian metallogenic and Mississippian belts and terranes for <strong>Alaska</strong>, Canadian<br />

Cordillera, and adjacent offshore areas. Refer to text for description of metallogenic belts. Adapted from Nokleberg and others<br />

(1997b, 1998). Refer to figure 3 for explanation.<br />

48

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