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Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
Lecture10 platetectonics
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Lecture10 platetectonics

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  • 1. Plate Tectonics Tectonic Plates of the Earth
  • 2. How can we explain the rock cycle?
    • Need to identify mechanisms by which rocks are
      • Heated and melted
      • Buried and metamorphosed
      • Pushed up into mountains to be eroded
  • 3. Earth as a jigsaw puzzle
    • Matching continental edges: recognized for centuries
    • Pangaea: supercontinent proposed by Wegener (1912)
  • 4. Wegener’s contribution
    • continental drift
    • = pattern of moving continents
  • 5. Theory of fixed continents
    • Traditional assumption: continents & ocean basins fixed in position
    • Problems
    • Matching continent edges
    • Matching fossils among continents
    • Matching geology among continents
  • 6. Evidence against fixed continents Matching edges Matching geology
  • 7. Bathymetry of the ocean floor continental shelf abyssal plain trench mid ocean ridge
  • 8. Thickness of the Sediment x 550 m x 102 m x 18 m x 112 m x 430 m 35 m x
  • 9. The Driving Mechanism
  • 10. Paleomagnetism
  • 11. Radiometric dating Red = younger, green = older
  • 12. Plate tectonics
    • = process for continental drift
    • Thermal convection system within Earth
      • 1. Making crust
      • 2. Destroying crust
      • Explains the rock cycle!
  • 13. Making crust
    • magma rises up from mantle, spreads out, & cools
    • occurs at spreading boundaries (called ridges)
    • process of sea-floor spreading
    Magma Ridge New crust Sea-floor spreading Asthenosphere Lithosphere Sea-floor spreading
  • 14.
    • crust descends into mantle & is recycled
    • occurs at converging boundaries (called trenches)
    • process called subduction
    Destroying crust Asthenosphere Subducting plate Trench
  • 15. Making crust + destroying crust = conveyor belt system = rock cycle (sort of) Convection or Buoyancy Ridge push Slab pull Convection cell in mantle
  • 16. Where are ridges & trenches? ridges trenches
  • 17. Geologic Excitement at Tectonic Plate Boundaries
  • 18. Global Seismicity
  • 19. Active Volcanoes
  • 20. 3 Major plate boundaries
    • Spreading
      • plates pulling apart
    • Converging
      • plates pushing together
    • Transform
      • plates sliding past each other
  • 21. 1. Spreading boundaries
    • also called divergent boundaries
    • includes ridges and rift valleys
    • e.g. Mid-Atlantic ridge, Great Rift Valley
  • 22.  
  • 23.  
  • 24. 2. 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
  • 25. Convergent boundaries Oceanic -Continental Oceanic-Oceanic Continental-Continental
  • 26. 3. Transform boundaries
    • associated w/ major seismic activity
    • e.g. San Andreas system
  • 27. Continental Drift Animation based on paleomaps from University of Texas Arlington http://www.ucmp.berkeley.edu/geology/anim1.html
  • 28. Plate tectonics: predicting the future
  • 29. 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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