Download plate tectonics

PLATE TECTONICS
Plate Tectonics
• The Theory of Plate Tectonics
states that the surface of the
earth is broken up into a few
large plates and many smaller
ones
Plate Tectonics
Plate Tectonics
• These solid plates float on the semisolid
mantle
• The plates interact with each other in three
major ways:
– Pull away from each other “Divergent”
– Move towards each other “Convergent”
– Slide past each other “Transform Fault”
Plate Tectonics
• Divergent
• Examples:
– Atlantic Ocean
Mid-Ocean
Ridge
– Red Sea
– Iceland
– African Rift
Valley
Plate Tectonics
Plate Tectonics
Plate Tectonics
Plate Tectonics
• Convergent
– Oceaniccontinental
– Oceanic-Oceanic
– ContinentalContinental
Plate Tectonics
• Oceanic-Continental
– Ocean plate sinks under the continental plate
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Subduction
Forms a Trench
Forms a Continental Volcanic Arc
Earthquakes
– Examples:
• West coast of the United States and South America
Plate Tectonics
• Oceanic-Oceanic
– One Ocean plate sinks under the other
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•
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•
Subduction
Forms a Trench
Forms a Volcanic Island Arc
Earthquakes
– Examples:
• Japan
• Caribbean Islands
Plate Tectonics
• Continental-Continental
– Continent crashes into Continent
• No subduction after Continents hit.
• Forms Mountains
• Earthquakes
– Examples:
• Himalayas
• Appalachia
• Urals
Plate Tectonics
• Transform Fault
– One plate grinds past another
• Deforms the surface
• Earthquakes
– Examples:
• San Andreas Fault
• Anatolian Fault – Turkey
• Chaman Fault - Pakistan
Plate Tectonics
• Evidence for Plate Tectonics
– Paleomagnetism
• The natural remnant magnetism in rock bodies
• When rock solidifies from the molten state the magnetic
crystals that form align with the magnetic field of the
earth.
• The Earths magnetic field has flipped many times in the
past.
• This shows up as alternating strips of polarity in the
rocks of the seafloor.
Plate Tectonics
• Evidence for Plate Tectonics
– Earthquake patterns
• Most earthquakes happen along plate boundaries and
happen at different depths according to the type of
boundary.
– Ocean Drilling
• Data on age of seafloor crust supports seafloor
spreading.
– Hot Spots
• Hawaiian Island chain supports the idea that the plates
are moving.
Plate Tectonics
• Mechanisms of Plate Tectonics
– Slab-Pull and Ridge-Push
• Slab-Pull – As the slab sinks down into the mantle it
pulls the rest of the plate after it.
• Ridge-Push – The push of the magma from the mantle
at the ridge causes the material at the top of the ridge to
fall down the sides of the ridge.
– Mantle Convection
• Currents of rock moving in the earths interior over
millions of years.
– Cool rock sinking – Hot rock rising