Geology Reference
In-Depth Information
Orogeny
Period
1.8
Laramide orogeny
66
Sevier orogeny
Nevadan orogeny
146
200
251
Sonoma orogeny
◗
Figure 22.11
Mesozoic Cordilleran Orogenies Mesozoic
orogenies occurring in the Cordilleran mobile belt.
◗
Figure 22.12
Cordilleran Batholiths Location of Jurassic and
Cretaceous batholiths in western North America.
Washington-
Oregon
Sea level
Sea level
Idaho
Oceanic
crust
Continental
crust
Upper mantle
a
High-angle subduction.
b
Low-angle subduction.
◗
Figure 22.13
Cretaceous Subduction in the Cordilleran Mobile Belt A possible cause for the
eastward migration of igneous activity in the Cordilleran region during the Cretaceous Period was a
change from
a
high-angle to
b
low-angle subduction. As the subducting plate moved downward
at a lower angle, the depth of melting moved further east.
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