Download Lecture Notes on Convection and Plate Tectonics

Lecture Notes on Convection and Plate Tectonics
© 2002 Ann Bykerk-Kauffman, Dept. of Geological and Environmental Sciences, California State University, Chico*
I.
Convection of a Fluid
A. Concept Map of Convection
B. Conditions Needed for Convection
1.
2.
*
Supported by NSF Grant #9455371. Permission is granted to reproduce this material for classroom use.
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Lecture Notes on Convection and Plate Tectonics
II. Convection in Earth's Mantle
A. Environmental Conditions in Earth's Interior
1. As you go deeper into Earth's interior, the temperature continually
2. Will this type of temperature distribution encourage convection?
3. What are the sources of heat in Earth's interior?
a.
b.
B. The Earth's mantle is made of solid rock. Convection happens in fluids. How can solid
rock convect?
1.
2.
III. The Relationship Between Mantle Convection and Plate Tectonics
A. Illustration of model (Figure 7.27B on p. 221 of the textbook)
Lecture Notes on Convection and Plate Tectonics
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B. Description of model
1. Upwelling convection currents
a. Location:
b. Description:
2. Downwelling convection currents
a. Location:
b. Description:
IV. What makes the plates move?
A. The slab-pull hypothesis: brief summary
spreading
ridge
subduction
zone
B. How does the slab-pull hypothesis work?
1. Densities:
{
Oceanic Crust: density =
Mantle lithosphere: density =
Asthenosphere: density =
2. Changes in oceanic plates with time (and with distance from the spreading ridge)
At spreading ridge
500 km away
1000 km away
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Lecture Notes on Convection and Plate Tectonics
3. What happens to the overall density of an oceanic plate as it moves away from the
spreading ridge?
4. Why do oceanic plates subduct?