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

(10) The Aleutian-Wrangell continental-margin arc was associated with mainly oblique subduction of the northern edge
of Pacific Ocean plate (PAC) along the Aleutian megathrust (AL) to form the Prince William terrane (PW). During northward
migration, the Yakutat terrane (YA) started to underthrust the Prince William terrane along the eastern part of the Aleutian
megathrust. Forming in the Aleutian-Wrangell continental-margin arc in Southern Alaska was the Alaska Peninsula and Aleutian
Islands (AP) metallogenic belt which contains granitic-magmatism-related deposits and is hosted in the Aleutian volcanic belt.
+ * + *
+ + + +
+ +
+
+ +
+C~LL+
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'
+ + t * + * t + +
COLLAGE OF
AP -AWbaPam?8ula and
Akamwmda
CK - CmKYndUfktl
EK - EaCllhnch&a
Figure 127. Middle Tertiary (Miocene - 20 to 10 Ma) stage of rnetallogenic-tectonic model. Refer to text for explanation of
rnetallogenic-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).
(1 1) Offshore of the southern Canadian Cordillera, sea-floor spreading continued along the Juan de Fuca Oceanic ridge
(JFF). Northward movement of the Pacific Ocean plate (PAC) and associated transform displacement on the Queen Charlotte
transform fault (QC) resulted in continued northward migration and subduction of the Yakutat terrane (YA) beneath the
continental margin of Southern Alaska.
(12) TO the south, the Cascade continental-margin arc continued activity. Associated with this arc was continued
subduction of part of the Juan de Fuca plate (JF) along the ancestor of the modern Cascadia megathrust (CC). Regional extension.
associated with back-arc spreading the behind Cascade arc (ca ), resulting in continental eruption of the Columbia River basalt (cr;
Wells and Heller, 1988; England and Wells, 1991). Continuing on fiom the early Tertiary in the Cascade arc was the was the Owl
Creek (OC) metallogenic belt, which contains granitic-magmatism-related deposits, and is interpreted during subduction-related
granitic plutonism.