USGS Professional Paper 1697 - Alaska Resources Library

160 Metallogenesis and Tectonics of the Russian Far East, Alaska, and the Canadian Cordillera
its, which are hosted in the Gravina-Nutzotin-Gambier belt that
overlies the Wrangellia superterrane. (8) Also in the Canadian
Cordillera, the Bayonne (BA), Cassiar (CA), Selwyn (SW),
Tombstone (TS), and Whitehorse (WH) belts, which contain
granitic-magmatism-related deposits, are also hosted in or near
anatectic granitic plutons of the Omineca-Selwyn plutonic belt
that is interpreted as forming during final accretion of Wrangellia
superterrane to North American continental margin. In the
below descriptions of metallogenic belts, a few of the noteable
or signficant lode deposits (table 4) are described for each belt.
Metallogenic-Tectonic Model for Late Early
Cretaceous (120 to 100 Ma; fig. 72)
During the late Early Cretaceous (Aptian through
Albian—120 to 100 Ma), the major metallogenic-tectonic
events were (table 3) (1) inception of the short-lived Khinghan
continental-margin arc and formation of associated metallogenic
belts and companion subduction zone in the Russian
Southeast, (2) accretion of the Mainitskiy island arc and
associated Alkatvaam (AV) accretionary-wedge terranes to the
active continental margin, (3) completion of accretion of the
60 o
o
At 50 latitude
AV
MO
COLL
uz
(BU)
AM, KB, KHINGAN
ZT
KLM ARC - ko
SA
ANV,
KK
KE
CA
MAI-MAINITSKIY
ARC
NSS NSC
BZ,
KH
(ud)
ANCESTRAL PACIFIC OCEAN
MA,
TAM
TD
UL
WK
wvk
CLOSING OF SOUTH ANYUI &
ANGAYUCHAM OCEANS
KU
NSV
KONY-MURGAL
ARC EK, YN
LE
AD
COLL
(KN)
(KLO)
(ol)
COLL
(MAI) (AV)
80 o
LS
NU CH
?
VE
ZL
VE
KOYUKUK
ARC
PK
WP
PEKUL’NEY
ARC
major Kolyma-Omolon superterrane in the Russian Northeast
and formation of associated metallogenic belts, (4) obduction
of Angayucham subduction-zone terrane onto the Arctic Alaska
terrane and formation of metallogenic belts during extension
that succeeded obduction, (5) continued opening of the
Amerasia, Canada, and Eurasia Basins, and (6) continuation of
the Gravina arc and formation of associated metallogenic belts
during continuing accretion of the Wrangellia superterrane, and
inception of collision-related metallogenic belts.
Specific Events for Late Early Cretaceous
(1) At about 50º paleolatitude, the Mainitskiy island arc
(Mainitskiy terrane, MAI) continued activity. Associated with
this arc was subduction of part of the adjacent oceanic plate to
form the Alkatvaam accretionary-wedge terrane (AV). This arc
and companion subduction zone continued to migrate northwards
towards the North Asian Craton Margin and outboard
terranes and was accreted to the active continental margin
at the end of the Early Cretaceous (about 100 Ma). During
this accretion, the Au quartz vein and associated deposits of
the Anadyr River (AD) metallogenic belt formed. The accre-
B SD
B
B
B
CO
AA
AG
KY
TG,
NY
B
B
B
B RB
NAM
TS SW
(NX, DL, UNK
MY)
(SV)
KI
?
120 to 100 Ma
WRA
(PE)
am
AA
NO SBR
kh
CONTINUED
OPENING OF
AMERASIA
BASIN
CG GRAVINA
ARC
WSE CG
FAR
COLLAGE OF
RIFTED
TERRANES:
NR, CK, CS, AP
OPENING OF
CANADA BASIN
gg
60 o
WRA
(AX)
FARALLON
OCEAN
METALLOGENIC BELTS
BA - Bayonne
BZ - Badzhal-Ezop
CA - Cassiar
KH - Khingan
KU - Kular
NO - Nome
SA - Samarka
SBR - Southern Brooks
Range
SW - NAC Selwyn
TS - Tombstone
WH - Whitehorse
WSE - Western-
Southwestern Alaska
CA COLL
(ST, QN,
(CA) CC, SM)
NAM
(KO)
WH
sb
BA
gg
WRA
BR,EA
(WR) MT
BA
0 800 km
0 800 mi
Figure 72. Late Early Cretaceous (Aptian through Albian—120 to 100 Ma) stage of metallogenic-tectonic model for the Russian Far
East, Alaska, and the Canadian Cordillera and adjacent offshore areas. Refer to text for explanation of metallogenic-tectonic events, to
tables 3 and 4 for descriptions metallogenic belts and significant deposits, and to figure 18 for explanation of abbreviations, symbols,
and patterns. Adapted from Nokleberg and others (1997b, 1998, 2000).