tectonic movement summary by 5wuVvO

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									Plate Tectonics




  Tectonic Plates of the Earth
           Plate tectonics
Today we will explore….
Different type of Plates
Different types of Plate Boundary (where the
  two plates are touching)
Different directions of plate movement
Results of what is created by all three of
  these items
                  Plate tectonics
Types of plates….(2)
 Oceanic Plate and Continental Plate
 mainly defined along the boundary where the two plates touch, for
 example…while most plates are comprised of both continental and oceanic crust
 the giant Pacific Plate is almost entirely oceanic, and the tiny Turkish-Aegean
 Plate is entirely land.

Plate Boundary…..(3)
  Ocean to Ocean
  Ocean to Continental
  Continental to Continental
              Plate tectonics
Direction of Movement (3)
 Plates are either…….

Convergent
    Colliding….there are 2 different types of convergent
Divergent
  Pulling apart (spreading)
Transgressional/Transformational
  Sliding past one another
               Plate tectonics
What happens when plates move, collide,
 etc
 Mountains, Trenches, Volcanoes, Islands, rift valley,
 earthquakes, etc, etc, etc
               Plate tectonics
Convergent Movement
 Two plates colliding….one usually goes down.
  Subduction –usually when an ocean plate collides with a
    continental plate the Ocean plate “subducts” under the
    continental plate.
  Over-riding –usually when a continental plate collides with
    another continental plate. One of the plates usually
    subducts, but the other plate will also Over-ride the other
    plate.
                        Plate tectonics
     Convergent Movement
Convergent plate boundaries have the following characteristics:
1. plate motion is toward plate boundary,
2. oceanic lithosphere sinks back into Earth and is recycled,
3. the volcanic arc is region of highly explosive volcanoes, like Mt. St. Helens and
Mt. Rainer in Washington,
4. The plate boundary is marked on the seafloor by a deep-sea trench, or just trench,
the deepest areas of the ocean,
5. These types of plate boundaries have the strongest earthquakes and most
explosive volcanic eruptions!
Ocean-to-continent subduction - An oceanic plate is subducted
beneath a continental plate, forming a trench adjacent to a continent, and volcanic
mountains along the edge of the continent.

Example: Peru-Chile Trench adjacent to the western coast of South America and the
Andes Mountains.
Note that the volcanic rocks in this setting tend to be andesite (named for Andes
Mountains) - coming from a mixture of basaltic and granitic magmas.
Ocean-to-ocean subduction - An oceanic plate is subducted
beneath another oceanic plate, forming a deep-sea trench, with an associated basaltic
volcanic island arc.

Examples: Marianas Trench adjacent to Mariana Islands, Aleutian Trench adjacent to
Aleutian Islands, Java Trench adjacent to Java, Sumatra, and Sunda Islands in the
Indonesian region.
A second type of convergent plate boundary involves the sinking of oceanic
lithosphere beneath another plate of oceanic lithosphere -- these regions have the
very deepest trenches along the seafloor and a line of volcanic islands, called an
island arc. Once again these regions have explosive volcanoes.
 Continental collisions (convergent movement also
 called Over-riding) form mountain belts with folded
 sedimentary rocks, and a central area of metamorphic
 rocks. and granitic igneous intrusions.
         Examples: Himalaya Mountains, Ural
         Mountains, Appalachian Mountains
                  * Non-volcanic




Continental to Continental Convergent
                 Converging
3 types
A. Oceanic-Continental  volcanic ranges
  e.g. Andes

B. Oceanic-Oceanic        volcanic island arcs
  e.g. Japan, Aleutian islands

C. Continental-Continental  mountain ranges
  e.g. Alps, Himalayas
               Plate tectonics
Divergent Movement
 Two plates pulling apart or spreading….they are “diverging” from
 each other.
  Most common when two oceanic plates are diverging, but can
    occur on land between two continental plates
            Divergent/Spreading boundaries




When a divergent boundary occurs beneath oceanic lithosphere, the rising
  convection current below lifts the lithosphere producing a mid-ocean ridge.
  Extensional forces stretch the lithosphere and produce a deep fissure

Examples - Mid-Atlantic ridge (two ocean plates),
           Great Rift Valley (two continental plates)
            Major Divergent Boundry




Animation
                         Plate tectonics
     Transformational Movement
        Two plates sliding past one another….usually involves one plate
        doing most of the moving, the other being stationary
         Ocean to continental plate - San Andreas
         Ocean and Ocean – Steps on the Mid Atlantic Ridge



Transform boundaries, in many places, form steps in the mid-ocean ridges.
These boundaries mark regions where one oceanic plate slips horizontally by another
oceanic plate -- lithosphere is neither created or recycled, but it is conserved.
Plate motion is parallel to the plate boundary and can result in very large earthquakes.
With a few exceptions, transform plate boundaries do not exhibit volcanoes, but can
right along the boundary (Calif does have volcanoes but eruptions are very rare)
                     Steps on Mid Atlantic Ridge




Ocean and Continental transformation
           Transform boundaries
• associated w/ major seismic activity
              How is it all connected?
      Earthquakes, faults, volcanoes, etc
We will do an activity that allows you to make connections with all types of movements
and what the produce.
Plate tectonics in the future: 50 my
•   Australia will straddle the equator
•   E. Africa will form new continent
•   Mediterranean will close off
•   Atlantic Ocean will grow
•   Pacific Ocean will shrink

								
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