Page 44 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

of
moun-
off
have
the
of
is
mountain
that
a
of
The
California
contain
or
an
Nevada
Collision
sedi-
at
the
valleys.
over-
through
on
include
are
rise,
27
sediments, is called
chain
region
depths
trench
(straight
chains
between
scraped
built
(as
of
2.9)
times
plate.
fluids
volcanoes
the
the
top
Boundaries
of
other
and
zones
Sierra
The
plates
(Fig.
close
systems
as
deep-sea
to
chain
2.18a).
broad
reach
the
Two
collisional
three
overriding
crust. The
northern
Jevel
are
ridges
a
(or “accrete”)
2.9).
depression
as
the
subduction
islands
where
oceans
The
converging
the
a
underlying rock
2.16a).
to
may
erupts
a
(Fig.
sea
of
(Fig.
arc
underneath
Plate
faulted, forming long
is
the
two
arc;
Sound.
part
above
its
trench,
accumulates
result
of Australia.
plate
and
basin/island
Philippine
collide;
entire
the
converge
Europe
to
to
,
surface
(Fig.
volcanic
of
from
A
are
parallel
plate
at
Types
attach
of
descending
arc.
Oregon
rise
the
chambers.
the
Puget
Himalayas,
wedges
other
the
Sometimes
driven
crust
thickened.
thrust
to
the
western
today);
overriding
may
of
and
island
of a
crust
of
and
materials
crust
often
and
north
form
both
wedge/forearc
to
landward
;
the
and
sediments
wedge
roots
Washington,
accretionary
may
are
it
Antilles,
magma
Valley
an
arc)
the
volcanic,
Asia
beneath
makes
to
arc, which
mantle
If
continental
Sea, and Timor,
and
the
fluids
crust.
and
of the
called
block
the
Asia
of
accretionary
shape. These
island
Zones
Earth,
compressed, folded
beneath
Willamette
Just
compressed
are
top
solidified
that
the
that
(continental)
Lesser
south-central
the
crust
crustal
islands,
subducts
one
of
California
plates.
of
the
trench/accretionary
island
of
or
on
Magma
hot
Subduction
part
of
from
cold, some
(continental
and
ranges
extends
trench
the
mountains
Aleutian,
so
blocks
of this
thick
Caribbean
wedge
are
an
the
volcanic
Valley,
is
thickens
is
structural
minerals
plate
crust.
and
crust
it
northern
of
that
the
thick
from
coastal
one
km. where
subcontinent
plate: portions
a
causing
surface juncture
and
Ocean/Ocean
wedge
are
Great
one
The
from
into
oceanic
the
islands
highest
of
continues,
or
magma
thick
the
extending
silicate
elevation.
one
rock
shallow
chain
as
deformed
basin.
crust,
crust.
in
(oceanic)
Farther
the
of
accretionary
Barbados, in
is the
form
subduction,
Mountains
mountains,
have
Prominent
150
and
The
of normal
examples
includes
resulting
basin
curved)
melting
oceanic
oceanic
forearc
is
Indian
gence
to
ranges
ments
riding
tains
both
plate
high
thin
and
100
the
Lanes iba mies there- and thicker, is crust Continental Zones Subduction Ocean/Continent subduct will crust oceanic with plate a crust; oceanic than buoyant, more fore is morphology resulting The 2.16b). (Fig. crust continental by capped one beneath sea deep a including zone, subduction ocean/ocean an in developed that to similar continental the on
in Continental the
shows active Asthenosphere Active Margin mountain
Shaded area rifting of the North American continent Range Province. Island Arc one volcanic (“island are” or “volcanic arc”). from continental to oceanic crust is at
2.15 and sian Forearc cg Basin az ~. Volcanic Ae
FIGURE the Basin Zone ede Pere an ae
Zone Accretionary Wedge Accretionary Formation of topography and structures at subduction zones. Two parallel and

Trench " as Subduction Trench er Both plates capped by oceanic crust. b) Oceanic lithosphere subducts beneath more buoyant the transition
Plate Tectonics Subduction Ocean Crust ¢ o—> Asthenosphere Continent Crust Ss ranges form, one structural (“accretionary wedge”) plate boundary, hence an “active continental margin.”
/ Oceanic Lithosphere / continental lithosphere. Box shows that
2 Oceanic
Chapter Ocean Water. Ocean 2.16
a) b) FIGURE a)
26