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Plate Tectonics

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http://dept.kent.edu/geology/ehlab/tectonics/convergent.gif ... http://dept.kent.edu/geology/ehlab/tectonics/transform.gif. Continental vs. oceanic crust ... – PowerPoint PPT presentation

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Title: Plate Tectonics


1
Plate Tectonics
2
Plate tectonics fundamentals
  • Evidence - plate tectonics unites many disparate
    observations
  • Sea-floor spreading - the oceans widening is the
    mechanism that moves the continents
  • Plate margins - convergent, divergent, transform
  • Continental crust vs. oceanic crust
  • The Earths interior lithosphere, mantle, core

3
http//imiloa.wcc.hawaii.edu/krupp/BIOL101/present
/lcture18/img009.jpg
4
Continental Drift
Alfred Wegener (1880-1930)
5
Wegeners version of continental drift (1912)
Wegener was correct… but he had no mechanism.
6
Plate tectonics - 1960s
  • New data
  • the age of the ocean floor
  • magnetic stripes

7
(No Transcript)
8
Magnetic Stripes and Seafloor Spreading
http//earth.geol.ksu.edu/liu/g640/figures/magneti
c.jpg
9
Magnetic Stripes and Seafloor Spreading
http//www.moorlandschool.co.uk/earth/earth_scienc
e/magnetic_stripes_anomalies_jpeg.gif
10
Magnetic Stripes and Seafloor Spreading
http//jove.geol.niu.edu/faculty/fischer/105_info/
105_E_notes/lecture_notes/Plate_Tectonics/PT_image
s/magnetic_stripes_form.gif
11
Seafloor spreading
12
How does seafloor spreading lead to continental
breakup?
http//www.ac.wwu.edu/debari/406/figs/divergent.j
peg
13
Plate margins
14
http//earth.geol.ksu.edu/sgao/g100/plots/1203_03_
plate.jpg
15
http//dept.kent.edu/geology/ehlab/tectonics/conve
rgent.gif
16
http//dept.kent.edu/geology/ehlab/tectonics/midoc
ean_ridge.gif
17
Transform fault plate boundaries
http//dept.kent.edu/geology/ehlab/tectonics/trans
form.gif
18
Continental vs. oceanic crust
http//earthquake.usgs.gov/image_glossary/images/c
rust.jpg
19
(No Transcript)
20
Oceanic vs. Continental Crust
  • Age
  • OC
  • CC 2-3 bya
  • Thickness
  • OC 5-7 kilometers thick
  • CC 10-70 km
  • Composition
  • OC basaltic
  • CC granitic
  • Density
  • OC 3.0 grams per cubic centimeter
  • CC 2.7 gm/cc

21
The Earths Interior
http//www.members.aol.com/rhaberlin/images/ptppti
nt.gif
22
(No Transcript)
23
We know the Earth is layered because of seismic
waves
http//geoweb.tamu.edu/courses/geol101/grossman/Ve
locity.struct.jpg
24
The Earths interior 2 bases for layering
  • Composition
  • Crust - mafic/felsic
  • Mantle - ultramafic
  • Viscosity/Velocity
  • Lithosphere - rigid non-flowable, 0-150km
  • Asthenosphere - soft flowable, 150-400 km (?
    upper mantle)
  • Mantle
  • - transition zone (400-670 km)
  • - lower mantle (670-2900 km)
  • Core

25
Mantle Convection the mechanism for plate
tectonics?
http//www.pbs.org/wgbh/aso/tryit/tectonics/images
/convectioncurrent.gif
26
http//earthquake.usgs.gov/image_glossary/oceanic_
spreading_ridge.html
27
Plate tectonics explains things, for example...
  • Mountain belts
  • The Hawaiian islands

28
http//www.ruf.rice.edu/leeman/hawempchain.jpg
29
(No Transcript)
30
http//www.eas.slu.edu/People/Students/Martinelli/
ES101/images/Chapter2005/fg05_21.jpg
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