USGS Professional Paper 1697 - Alaska Resources Library

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,
Goose Creek
40
45
Foot
Lake
0 1 2 km
Lake
Ellen
Lake No 3
45
30 80
45
50
Rush and
Brown Mine
North Lake
20 30
Salt Chuck Mine
85
Power Lake
20
Lakes, tide-water, and tidal zones (Holocene)
Surficial deposits (Holocene). Chiefly alluvium,
tidal mudflat, and glaciofluvial deposits
Quartz diorite porphyry (Cretaceous?). Contains
large plagioclase phenocrysts
Metaigneous complex (Early Devonian to Early
Ordovican). Chiefly hornblende and (or) quartz
chloritic magmatite, leucogabbro, trondhjemite, and
minor pyroxenite. Cut by mafic and felsic dike swarms
Salt Chuck intrusion (Early Devonian? to Early Ordovician).
Chiefly sulfide-bearing clinopyroxenite and gabbro.
Gabbro
Clinopyroxenite
Undivided gabbro and clinopyroxenite
65
40
Descon Formation (Lower Silurian and Ordovician).
Stream
Contact, approximately located
Fault, approximately located
Strike and dip of cumulate layering
Strike and dip of bedding
Mine shaft
Salt Chuck
40
Loon
Lake
Figure 15. Salt Chuck zoned mafic-ultramafic Cu-Au-PGE
deposit, Prince of Wales Island metallogenic belt, southeastern
Alaska. Schematic geologic map. Adapted from Loney and Himmelberg
(1992). See figure 3 and table 4 for location.
Middle and Late Devonian Metallogenic Belts (387 to 360 Ma; figures 16, 17) 37
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 that intruded 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 forming during anatectic
granitic plutonism that 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 that 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.
(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
part of Mystic (MY), Robb Lake (RL), Selennyakh River
(SEL), Sette-Daban (SD), Southern Rocky Mountain (SRM),
Tommot 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.