Plate Tectonics
Plate Tectonics
Plate Tectonics
Major
Divisions
of Earth
Plate Tectonics
Different
Properties
Plate Tectonics
Rigid
Plastic
Plate Tectonics
The outer layer is the thinnest
= Crust
Two kinds of Crust
Plate Tectonics
• continental crust:
thicker, light
(granite)
2.7g/cm³
• oceanic:
thinner, dense
(basalt)
3.3 g/cm³
Plate Tectonics
• Each Tectonic Plate:
Oceanic crust
or
Oceanic & Continental crust
Plate Tectonics
• Each Tectonic Plate:
Oceanic crust
or
Oceanic & Continental crust
(none with continent only)
Plate Tectonics
• Oceanic crust or
Oceanic & Continental crust
Plate Tectonics
• Active continental margin:
leading edge of plate
(earthquakes, volcanoes,
steep mountains)
Plate Tectonics
• Passive continental margin:
trailing edge of continent
(eroded mountains, flat plains,
little activity)
http://www.simonwinchester.com/images/map1_large.jpg
http://www.simonwinchester.com/images/map1_large.jpg
Plate Tectonics
Classification of
Plate Boundaries
Plate Tectonics
I. Divergent Boundaries:
• tension =
pull  apart
• normal faults
Plate Tectonics
I. Divergent Boundaries:
• tension =
pull  apart
http://web.mala.bc.ca/earle/geol201/rift-valley2.gif
• normal faults
Plate Tectonics
I. Divergent Boundaries:
• new ocean crust formed
• mid-ocean ridge with a
rift valley down the middle
Plate Tectonics
I. Divergent Boundaries:
young basin
Plate Tectonics
I. Divergent Boundaries:
mature basin
Plate Tectonics
I. Convergent Boundaries:
• compression =
push  together
• reverse faults
Plate Tectonics
I. Convergent Boundaries:
http://geology.wr.usgs.gov/parks/deform/hangfootwall.gif
• compression =
push  together
• reverse faults
Plate Tectonics
I. Convergent Boundaries:
http://geology.wr.usgs.gov/parks/deform/hangfootwall.gif
• folding & uplift
earthquakes
Plate Tectonics
Three kinds of
Convergent Margins
(Crust Type)
oc - oc
oc - cont.
cont. - cont.
Plate Tectonics
IIa. Ocean - Ocean
• deep sea trench
• subduction zone (recyle)
• volcanoes & uplift
Aleutians, Japan, Philippines, Indonesia
Plate Tectonics
IIb. Ocean - Continent
• deep sea trench
• subduction zone
(recycle ocean side)
• volcanoes & major uplift
Plate Tectonics
IIb. Ocean - Continent
Andes, Cascades
Plate Tectonics
IIc. Continent - Continent
• collision
• no subduction, no vulconism
(can't recyle continents)
• heat & pressure, folding
& major uplift
Plate Tectonics
IIc. Continent - Continent
Himalayas
Plate Tectonics
III. Transform Plate boundaries
• shear = sliding past
in opposite directions
• lateral movement
with earthquakes
Plate Tectonics
III. Transform Plate boundaries
California
San Andreas fault