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Types of Plate Boundaries (finish Chapter 4)

Types of Plate Boundaries (finish Chapter 4). Hot Spots – more evidence for plate tectonics Divergent, Convergent and Transform plate boundaries - some examples California’s complicated tectonic setting – how it defines our local geography. Ocean island and seamount chains.

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Types of Plate Boundaries (finish Chapter 4)

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  1. Types of Plate Boundaries (finish Chapter 4) • Hot Spots – more evidence for plate tectonics • Divergent, Convergent and Transform plate boundaries - some examples • California’s complicated tectonic setting – how it defines our local geography

  2. Ocean island and seamount chains Most earthquakes and volcanic eruptions occur near plate boundaries – but not all. The Hawaiian Islands are large volcanoes that have formed in the middle of the Pacific Plate. Does this fit into plate tectonic theory? http://pubs.usgs.gov/gip/dynamic/hotspots.html#anchor19620979

  3. Hot Spots – places where there has been continuous volcanism for a long period of time – sites of ‘leaks’ or ‘mantle plumes’ They provide measurements of absolute rates of plate motion Hot spot older younger Subduction zone (crust destroyed) Plates converge (compress) Midocean ridge (crust created) Plates diverge (move apart)

  4. The hypothesis that islands increase in age with distance from the current hot spot mantle plume is correct http://volcano.und.edu/vwdocs/vwlessons/hot_spot_pics/ages_of_islands.gif

  5. Types of Plate Margins • Divergent – new crust is generated where plates pull apart • Convergent – crust is consumed in the mantle as one plate dives under another • Transform – plates slide horizontally past one another – crust is neither created nor consumed Figure 4.17, Skinner et al., 1999

  6. Mid-ocean ridges- divergent margins where new ocean crust is made as plates pull apart Gakkel Ridge Flyby Juan de Fuca Ridge

  7. Mid ocean Ridges Figure 4.18, Skinner et al., 1999

  8. Formation of new crust at MOR “pillow” lava http://oceanexplorer.noaa.gov/explorations/02fire/background/plumes/media/fig2.html

  9. http://www.geophysics.rice.edu/plateboundary/age.72.gif Fast spreading rate Slow spreading rate Mid ocean ridges are also divergent margins

  10. Formation of Divergent Margins Figure 4.18 Skinner et al., 1999

  11. Examples of divergent margins – land being split apart Iceland Gulf of California East African Rift

  12. Convergent Margins: Collision Zones Figure 4.24, Skinner et al., 1999

  13. Convergent Margins Features of Subduction Zones Figure 4.20, Skinner et al., 1999

  14. Convergent Margin examples

  15. Convergent Plate Boundary – Aleutian Arc http://www.geophysics.rice.edu/plateboundary/aleut1.pdf

  16. http://www.moorlandschool.co.uk/earth/tectonic.htm

  17. 200 million years ago to Present http://www.ucmp.berkeley.edu/geology/tectonics.html

  18. Tectonic setting for Sumatra/Andaman Earthquakes Subduction zone http://www.soc.soton.ac.uk/soc_home2.php?pagetype=news3&idx=212

  19. Transform Margins: The San Andreas Fault Figure 4.25, Skinner et al., 1999

  20. http://www.geophysics.rice. edu/plateboundary/cal1.pdf

  21. California’s complex Tectonic Setting Juan de Fuca plate being subducted under North American plate Volcanoes line up inland of subduction zone California’s big cities are actually on the Pacific plate and moving northwest with it – plate boundary is the San Andreas Fault (a transform fault) Spreading center – splitting Baja California from Mexico and causing Basin and Range crust expansion http://geography.sierra.cc.ca.us/booth/California/1_lithosphere/plates_west_coast.jpg

  22. http://www2.nature.nps.gov/geology/usgsnps/province/INDEXbasinRangeSUBS.gifhttp://www2.nature.nps.gov/geology/usgsnps/province/INDEXbasinRangeSUBS.gif

  23. http://www.gly.uga.edu/railsback/1121NAWestBasin&Range.jpeg

  24. http://geography.sierra.cc.ca.us/booth/California/1_lithosphere/TransRanges_Big.gifhttp://geography.sierra.cc.ca.us/booth/California/1_lithosphere/TransRanges_Big.gif

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