chapter 3

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chapter 3
2011-10-08 02:27:39

plate techtonics
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  1. what happened in hadean eon?
    • extraterretrial barrage
    • new, noxious atmosphere
    • heating earths interior
    • magma ocean
  2. what the "iron catastrophe"?
    • eventual cooling
    • earliest crust and ocean
  3. what happens during chemical differentiation?
    lighter elements to top and heavier elements to middle
  4. what are feature of the core?
    • inner core= solid iron
    • outer core= iron rich fluid
    • creates earth geomagnetic field
  5. what are features of the mantle?
    • lower mantle hotter
    • upper cooler\
    • convection plumes
    • lower llithosphere rest on asthenosphere
  6. what are features of the continental crust?
    • continental crust hotter than oceanic
    • thicker than ocenaic
    • lower density "floats" on mantle
  7. what are features of oceanic crust?
    iron and magnesium rich
  8. mantle plumes
    warm rock rises, cool rock descends
  9. ______ plates carry continents and oceans
  10. what is the tectonic theory?
    • earth lithosphere broken into plates that move and interact
    • plate move in response to forces in mantle
  11. how many major lithospheric plates are there?
  12. what are subduction zones?
    • plates recycled into mantle
    • characterized by deep sea trenches
    • denser plate subducts beneath less dense plate
  13. what happens at spreading centers?
    magma errupts from mantle. new rock added to plate margin
  14. geomagnetic field switches from _______ to ________ on irregular basis
    • reversed polarity
    • normal polarity
  15. what incorporated earths new magnetic orientation?
    iron crystals in magma
  16. iron rich sediment particles align with geomagnetic field like compass needles (T/F)
  17. when lithified ________ and ________ sediments permanently record orientation of geomagnetic field at that time
    • magma
    • sediments
  18. explain paleomagnetism at divergent plate boundaries:
    • two or more plates pull apart
    • molten rises through rift zone
    • newest magma on either side of rift
    • newest crust travel away from center on each side
    • oceanic crust records reversed and normal polarity
  19. what is the ring of fire?
    most seismically and volcanic active zone in world
  20. what is divergent plate boundary?
    new lithospher forms as plate pulls apart
  21. what is transformed plate boundary?
    • plates grind past each other
    • no change in lithosphere
  22. what is convergent plate boundary?
    one plate goes underneath another or two plates collide without subducting
  23. seafloor spreading leads to formation of new crust, what is it enriched with?
    iron and magnesium
  24. explain oceanic continent convergent boundary:
    plate of oceanic crust collide with plate of continental crust. oceanic crust is subducted under continental plate
  25. explain ocean ocean convergent boundary:
    two oceanic crust plated collide. older denser plate usually subducts, site of island arc formation
  26. as a plate subducts ______ is scraped off
  27. what is a wedge calle because of its three-dimensional shape
    acretionary prism
  28. explain continent continent convergent boundaries:
    convergence of indian and eurasian plates