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04.Plate Tectonics[1]
 

04.Plate Tectonics[1]

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    04.Plate Tectonics[1] 04.Plate Tectonics[1] Presentation Transcript

    • Geo 100- Useful Information
      • Course Homepage: http://mercury.atmos.albany.edu/geo100/
      • For SKN, email your name to instructor at
      • [email_address]
    • Theory of Plate Tectonics – an overview Geo 100N Spring 2005
    • Plate Tectonics -Overview
      • The Lithosphere and Crust
      • Basic Concepts of Plate Tectonics
      • Plate Movements and Boundaries
      • Summary
    • Inside the Earth USGS
    • The Lithosphere http://volcano.und.edu/vwdocs/vwlessons/plate_tectonics/part1.html
    • Basic Concepts of Plate Tectonics
    • The Earth’s surface is covered by about 12 lithospheric plates USGS
    • The plates move slowly (a few cm/year). USGS
    • Most endogenic geological activity occurs at or near plate boundaries. Mt St Helens, 1980 Endogenic = process that originates within the Earth’s interior
    • Plate interiors are relatively quiet geologically
    • Plate Movements and Boundaries
    • Divergent boundaries
      • Plates move apart
      • Volcanic activity is always present
      • Earthquakes are shallow
      • Two types of boundaries:
        • Oceanic
        • Continental
    • Oceanic Divergent Boundary
      • Sea-floor spreading of oceanic lithosphere
      • examples: Mid Atlantic Ridge, East Pacific Ridge
      USGS
    • Sea-floor spreading of oceanic lithosphere USGS, Digital elevation model
    • Mid Atlantic Rift at Iceland Þingvellir (Thingvellir), Iceland
    • Continental Divergent Boundary
      • Continental rifting
      • Eventually, oceanic crust is formed and divergence becomes oceanic type
      • Modern Example: East Africa
    • East African Rift Zone Oldoinyo Lengai, Kenya
    • Convergent boundaries
      • Plates move toward each other
      • Volcanic activity common
      • Deep, medium, and shallow earthquakes
      • Three types of Convergent Boundaries
        • Ocean-ocean
        • Ocean-continent
        • Continent-continent
    • Ocean-ocean convergence
      • Subduction – one oceanic plate subducts (dives) beneath the other
      • Volcanic island arc is formed
      • Example: Aleutian Islands
    • Aleutian Islands, Alaska Kanaga
    • Ocean-continent convergence
      • During ocean-continent convergence, oceanic lithosphere always subducts beneath continental lithosphere
      • Continental volcanic arc formed
      • Example: Andes mountains
    •  
    •  
    • Continent-continent convergence
      • Subduction does not occur (continental crust is too buoyant to be subducted)
      • Mountain building occurs without volcanism
      • Example: Himalayas, Alps
    • India-Asia Collision
      • Collision of India with Eurasian plate caused uplift of the Himalaya, the highest mountains on Earth.
    • Transform boundaries
      • Plates slide past each other
      • Little or no volcanic activity
      • Shallow earthquakes
      • Example: oceanic transform faults; San Andreas Fault
    • San Andreas Fault
      • Pacific plate is moving NW relative to the North American Plate
      • As plates move, transform fault slips, and earthquakes occur
    • Summary
      • Earth’s surface is covered by about 12 lithospheric plates.
      • The plates move slowly (2.5-15 cm/year).
      • Most volcanism and earthquake activity occurs at or near plate boundaries.
      • Plate interiors are relatively quiet geologically (some exceptions).
    • Geo 100- Useful Information
      • Course Homepage: http://mercury.atmos.albany.edu/geo100/
      • For SKN, email your name to instructor at
      • [email_address]