USGS Professional Paper 1697 - Alaska Resources Library

dilemma consists of two conflicting hypotheses for the loci
of accretion of the Wrangellia superterrane, which constitutes
most of the Insular superterrane, and the Intermontane superterrane
that consists of the Stikinia, Quesnellia, and Cache
Creek terranes (Cowan, 1994; Cowan and others, 1997). One
hypothesis, based on geologic evidence, including magmatic,
stratigraphic, and faunal ties, interprets the Wrangellia
superterrane as accreting at a northerly paleolatitude, approximately
at its present latitude. The other hypothesis, based on
paleomagnetic data for both continental volcanic rocks and
coeval plutonic rocks, interprets the Wrangellia superterrane
and the western part of the Intermontane terrane as accreting
at a paleolatitude approximately 3,000 km farther south.
This hypothesis is informally named the Baja British Columbia
controversy, in reference to accretion of the Wrangellia
superterrane at the approximate latitude of Baja California
(Umhoefer, 1987; Cowan and others, 1997; Dickinson and
Butler, 1998). For the synthesis of the tectonic evolution of
the Circum-North Pacific, these two hypothesis are called
the northern-accretion interpretation and southern-accretion
interpretation. For the metallogenic analysis of the Wrangellia
superterrane in the Mesozoic and early Cenozoic, only the
northern-accretion interpretation is considered. For additional
information and references for both interpretations, please
refer to the discussion and references in Nokleberg and others
(2000).
Proterozoic Metallogenic Belts (2500
to 570 Ma; figures 2, 3)
Overview
The major Proterozoic 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
(and their major mineral deposit types) are as follows (1) In
the central and southeastern part of the Russian Northeast,
are the Bilyakchan (BI) (basaltic Cu), Oroek (OK) (ironstone
and sediment-hosted Cu), Omolon (OM) (Ironstone (Superior
Fe)), and Ulkan (UL) (Felsic Plutonic REE and related deposits)
metallogenic belts. These belts are interpreted as forming
during incipient rifting of the passive continental margin of
the North Asian Craton or Craton Margin. (2) In the same
region are the Lantarsky-Dzhugdzhur (LD) metallogenic belts
of anorthosite-hosted apatite Ti-Fe and gabbroic Cu-Ni-Co-
PGE that is interpreted as forming during Mesoproterozoic
rifting of passive continental margin of North Asian Craton.
(3) On the Seward Peninsula in western Alaska, the Sinuk
River (SR) metallogenic belt, which contains massive sulfidebarite
and stratabound Fe-Mn deposits, is hosted in Proterozoic
or older metavolcanic and sedimentary rock. The belt is
interpreted as forming during marine volcanogenic rifting(?)
of the North American Continental Margin. (4) In southwest-
Proterozoic Metallogenic Belts (2500 to 570 Ma; figures 2, 3) 9
ern Alaska, the Kilbuck (KI) metallogenic belt, which contains
mainly ironstone (Superior Fe) deposits, is hosted in the
Kilbuck-Idono cratonal terrane and is interpreted as forming
during rifting of the North Asian Craton. (5) In the northern
part of the Canadian Cordillera is the Wernecke (WR) metallogenic
belt of U-Cu-Fe (Au-Co) vein and breccia deposits.
This belt is hosted in the North American Craton Margin and
is interpreted as forming during hydrothermal activity along a
Paleoproterozoic passive continental margin. (6) In the same
region is the Gillespie (GE) metallogenic belt of sedimentary
exhalative (SEDEX) Pb-Zn deposits that is hosted in the
North American Craton Margin and is interpreted as forming
during intrusion of gabbro and diorite sills during Paleoproterozoic
rifting. (7) In the same region is the Rapitan (RA)
metallogenic belt of iron formation deposits that is hosted in
the North American Craton Margin. This belt is interpreted
as forming during marine exhalation along Mesoproterozoic
North American Craton Margin. (8) In the same region is the
Redstone (RD) metallogenic belt of sediment-hosted Cu-Ag.
deposits that is hosted in the North American Craton Margin.
This belt is interpreted as forming during incipient Neoproterozoic
rifting of the North American Craton Margin. (9)
In the southern Canadian Cordillera is the Monashee (RD)
metallogenic belt of SEDEX Zn-Pb-Ag deposits . This belt,
which is hosted in the Monashee terrane, is interpreted as a
fragment of the North American Craton and formed during
Late Proterozoic rifting of North American Craton. (10)
In the same region, the Purcell (PR) belt of massive sulfide
deposits is hosted in the North American Craton Margin and
is interpreted as forming during incipient rifting of the craton.
(11) In the same region, the Clark Range (CR) belt of sediment-hosted
Cu-Ag deposits is hosted in the North American
Craton Margin, and is interpreted as forming during incipient
rifting of the craton margin. In the below descriptions of
metallogenic belts, only notable examples of significant lode
deposits are described for each belt. table 4, which is adapted
and revised from Nokleberg and others (1997a), lists the significant
lode deposits in each metallogenic belt.
Metallogenic Belts Formed During Proterozoic
Rifting of North Asian Craton or Craton Margin
Oroek Metallogenic Belt of Ironstone and
Sediment-Hosted Cu Deposits (Belt OK),
West-Central Part of Russian Northeast
The Oroek metallogenic belt of ironstone and sediment-hosted
Cu deposits (fig. 2; tables 3, 4)occurs mainly in
the Shamanikha River basin in the central part of the Russian
Northeast (Shpikerman, 1998). The belt is hosted in the
Shamanikha subterrane of the Prikolyma passive continental
margin terrane of the Kolyma-Omolon superterrane (Nokleberg
and others, 1994c, 1997c). The belt trends north-south
for 400 km along the axis of the Prikolyma terrane and has a