Plate Tectonics and Earth

1
Plate Tectonicsand Earths Interior
2
Pangea
3
Distribution of Late Paleozoic Fossils
4
Conventional WisdomAnimals Migrated Across Land
Bridges
5
Late Paleozoic Glaciation
6
Distribution of Ancient Mountain Belts
7
Patterns Fit,But Is It Possible?

• Tremendous amount of energy needed to move
  continents around the globe
• Wegener proposed that centrifugal force on the
  spinning Earth pushed continents from the south
  pole to the equator
• Modeling/simulation indicated that this would be
  insufficient
• Wegener proposed that the moving continents
  plowed through the oceans like an icebreaker
• Experiments indicated that oceanic rock is
  stronger than continental rock, and so oceans
  would have cut through the continents

Continental Drift was a Model without a Mechanism!
8
Bathymetry of the Ocean Floor
9
(No Transcript)
10
Volcanoes of the World
11
Volcanoes Correlate Globally with Deep Earthquakes
12
Benioff Zone of Seismicity
13
Plate Tectonic Model
14
Tectonic Plates
15
Seismic Waves
16
Seismic Wave Velocities
17
Seismic Wave Paths
S-Waves
P-Waves
18
Layers Within Earth
19
Convection Cells and Plate Movements
20
Plate Tectonic Model
21
Differentiation Basalt

• Partial melting of peridotite will form basaltic
  magma
• Basaltic magmas are formed from melting mantle
  due to upwelling heat

22
Differentiation Andesite

• Partial melting of basalt will form an andesitic
  or granitic magma
• Andesitic magmas are formed from melting oceanic
  crust
• Subducting plate releases water (a flux) into
  mantle
• Magma pools under crust and partially melts the
  oceanic crust

23
Differentiation Granite

• Partial melting of andesite will form granitic
  magma
• Granitic magmas are formed from melting of
  continental crust
• Subducting plate releases water (a flux) into
  mantle
• Magma pools under crust and partially melts the
  continental crust

24
Sources of Heat for Metamorphism

• Heat from Earths interior
• Geothermal gradient is the increase in
  temperature with depth
• Typical continental geothermal gradient is
  25-30C/km
• Volcanically active areas have geothermal
  gradients of 30-50C/km
• Oceanic trenches have geothermal gradients as low
  as5-10C/km

25
(No Transcript)