Download Plate Tectonics 2 ppt

Ocean-Ocean Convergent Boundary
Two oceanic plates
move toward one
another
Trench and island arc
One plate moves
down = subduction
03.05.a1
Features and Processes in Ocean-Ocean Convergence
Trench
Eruptions form volcanic
island arc
Accretionary
prism
Slab releases water
Water causes
melting of mantle
Sketch ocean-ocean convergence, labeling the
processes in your own words
03.05.a1
Ocean-Continent Convergent Boundary
Oceanic and continental
plate converge
Volcanoes and squeezing
form mountain belt
Trench
Oceanic plate subducted
beneath continent
Overlying mantle
melted
Sketch ocean-continent convergence, labeling the
processes in your own words
03.05.b1
Observe the distribution of volcanoes around the Pacific Ring
of Fire
What do
you
think
could
explain
the
overall
pattern?
03.05.c1
Pacific Ring of Fire
Oceanic plates subducted
on both sides
Spreading in East
Pacific Rise
Subduction beneath
oceanic plates = island
arcs (e.g., Japan)
Subduction beneath continental
plates = mountain belts with
volcanoes (e.g., Andes)
Explain the Pacific Ring of Fire, including why
the west and east sides are different
03.05.c2
Continent-Continent
Convergence
Two continents collide
Subduction
of oceanic
part of plate
Subduction
brings continents
closer
Continents
collide
03.05.d
Continental collision = wide zone of deformation
Pieces sliced off
Thick crust = high elevation
Few volcanoes
Continental plate
buoyant, so
subduction ends
Sketch a continental collision, labeling the
processes in your own words
03.05.d3
Transform Boundary
Observe how these two “plates” are moving
past each other
Transforms link
spreading segments
in mid-ocean ridges
Plates move
horizontally
past one
another on
transform
boundaries
Transforms
link other
types of plate
boundaries
03.06.a1
Observe the pattern of the Mid-Atlantic Ridge
Spreading
segments
Transforms link
spreading
segments
03.06.a2
Sketch a transform boundary, labeling the
processes in your own words
Observe plate boundaries near the west coast of
North America (green lines are transform boundaries)
03.06.b1
What Moves the Plates?
Ridge push
Slab pull
Other forces, such as
convection in mantle
03.07.a1
Rates of Relative Plate Movement
Plates move cm/year
Some move faster than others
03.07.b1
Which plate boundaries have the fastest rates?
Geometry of Plate Boundaries
Observe how the motion of these two plates varies as the
boundary changes orientation
Spreading along
this orientation
As boundary changes
orientation, plates
move horizontally past
one another
Transform
boundaries link
other types of plate
boundaries, like two
spreading centers
or a spreading
center with a
subduction zone
03.07.d1
Geometry of Plate Boundaries II
Observe how the motion between the North American and
Pacific plates varies as the boundary changes orientation
As boundary bends,
becomes convergent
(Pacific plate subducted
beneath NA)
Transform boundary here
(Queen Charlotte fault), with
plates moving horizontally
past one another
03.07.d1
Test of Plate Tectonics Is Age of Seafloor
and Thickness of Sediment
Drill
cores
Volcanic rocks in
crust youngest near
ridge (just formed)
Sediment
Volcanic rocks
Sediment thickens away
from ridge (had more
time to accumulate)
03.08.a1
Formation of Linear Island
and Seamount Chains
Lines of islands and
seamounts (e.g., Hawaii)
Plate moves over a hot spot
Plate subsides
as cools, so
islands become
seamounts
Volcano
forms over
a hot spot
Volcanoes become inactive as
area moves away from hot spot
03.08.c
Why is South America Lopsided
Observe the
features
around South
America
Envision a
cross section
from west of
South
America
to the MidAtlantic
Ridge
03.09.a1
Compare this cross section with the
one you envisioned
Andes (mountains and
volcanoes) over subduction
zone, with trench offshore
Subduction beneath
western edge
Spreading along
mid-ocean ridge
Eastern edge of
continent not a
plate boundary
(passive margin)
03.09.b1
Middle
Mesozoic
(140 m.y ago)
Late
Mesozoic
(100 m.y ago)
Evolution of
South America
Observe the
evolution of
South America,
beginning with
continental rifting
away from South
America
Present
03.09.c
Investigation: Where is the Safest Place to Live
Continent
A
Continent
B
Identify possible plate boundaries in this area and indicate
whether the boundary is divergent, convergent, or transform
Identify where you would get earthquakes and volcanoes,
and then determine where it is safest to live
03.10.a1
Sketch the geometry of the plates in the subsurface, using
figures in the textbook as a guide to the geometries of the
plates and thickness of the lithosphere, oceanic crust, and
continental crust
03.10.a