plate tectonics geol 101 lecture 24pages.geo.wvu.edu/~kite/geol101_2006lect24platetectiii.pdf ·...
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Plate Tectonics GEOL 101 Lecture 24
Prop: Test 3 Invitations
The Grand Tetons, WyomingHow Are Mountains Built?
Spread Centers Feed Subduction Zones
Missing Mechanisms for Continental Drift:Sea Floor Spreading & Subduction
Continents are Passive “Boats”
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Subduction Zones: Ocean-Ocean Margin
Subduction Zones: Ocean-Continent Margin
Orogeny Associated with Subduction ZoneSingle Figure with Some Vertical Exaggeration
Plummer et al. 10th ed, Figure 20.6
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Orogeny Associated with Subduction ZoneSingle Figure with More Vertical Exaggeration
Orogeny Associated with Subduction Zone
Cra
ton Fold and Thrust Belt
“Orogeny” Flipped for East Coast View
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Orogeny Associated with Subduction ZoneSingle Figure – Flipped & Tilted to Match Eastern US
Younger Sed Rx
Sea Level TodaySh
enan
doah
N
atl.
Park
Himalayas
How Are Really Big Mountains Built?
Orogeny in the Himalayas
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Continental Lithosphere
Will NOT Flush Down Subduction
Zones
Orogeny Folds Rocks
Review: New Lithosphere (Crust + Upper Mantle) is
Created at Spread Centers, Consumed at Subduction Zones
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What About Offsets in Spread Centers?
Transform Faults & Fracture Zones
Transform Faults
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San Andreas Fault:Right-Lateral
Transform Fault
Left-Lateral Offset!!Why?: Fault is
Produced by Offset, vs. Offset Produced by Fault
Plate Margins:
• Spread Centers (Mid-Ocean Ridges)• Subduction Zones (Trenches)• Transform Faults
Plate Margins:
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The Plates: Atlantic-Centered View
The Plates: Pacific-Centered View(Distorted by Mercator Map Projection)
What Drives Plate Tectonics?
1. Convection Cells in Mantle 2. Sinking of Cool, Dense Plates3. Mantle Plumes - Hot Spots
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Convection Cells
Convection Cells in MantleConvection Cells in Mantle
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Mantle Plumes
Mantle Plumes Under Continents
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• Known “Hot Spots”
Hawaiian Islands
Mantle Plumes - Hot Spots
•
Numbers = Age of Rockin Millions
of Years
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Sinking of Cool, Dense Plates
Seamount
Volcanoes Surrounded by Fringing Coral Reefs
NASA
Atolls: Submerged Volcanos Support ReefsOnly in Warm Clear Seas
Tuamoto Islands
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Continental Accretion
• The Craton: The Old Core of the Continent
• Mostly Exposed in the CnanadianShield
Craton
Craton
Plate Tectonic Evolution of Eastern North America
• Suspect Terranes
Accreted or “Suspect”Terranes in Western
USA, Canada
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History of “Suspect” Terrane
Accretion in Western North
America
Plate Tectonic Evolution of North America:
Accretion of Terranes
• suspect terranes (AK)
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Source:http://vishnu.glg.nau.
edu/rcb/
WVU
WVU
Source:http://vishnu.glg.nau.
edu/rcb/
WVU
WVU
Source:http://vishnu.glg.nau.
edu/rcb/ WVU
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Source:http://vishnu.glg.nau.
edu/rcb/ WVU
Source:http://vishnu.glg.nau.
edu/rcb/ WVU
Source:http://vishnu.glg.nau.
edu/rcb/
Taconic OrogenyContinent-Arc Collision
WVU
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Orogeny: Eastern N. Amer.
“Mirror” Image of West Coast
Source:http://vishnu.glg.nau.
edu/rcb/
Taconic Orogeny
WVU
Source:http://vishnu.glg.nau.
edu/rcb/ WVU
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Source:http://vishnu.glg.nau.
edu/rcb/
Acadian OrogenyContinent-”Terrane” Collision
WVU
Source:http://vishnu.glg.nau.
edu/rcb/
Acadian Orogeny
WVU
Source:http://vishnu.glg.nau.
edu/rcb/ WVU
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Source:http://vishnu.glg.nau.
edu/rcb/
WVU
Source:http://vishnu.glg.nau.
edu/rcb/
Alleghenian OrogenyContinent-Continent Collision
WVU
Allegehenian Orogeny Folded Appalachian Rocks
“Mirror” Image of West Coast
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Source:http://vishnu.glg.nau.
edu/rcb/Penn.jpg
Pangaea = Gondwanaland +
Laurasia
Source:http://vishnu.glg.nau.
edu/rcb/
Alleghenian Orogeny
WVU
Source:http://vishnu.glg.nau.
edu/rcb/Perm.jpg
Pangaea = Gondwanaland
+ Laurasia
Ice Sheet
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Erosion and Isostatic Uplift of the Appalachians Since End of AlleghenianOrogeny
Laurasia
Gondwanaland
Source: http://vishnu.glg.nau.edu/rcb/160_1st.jpg
WVU
Source:http://vishnu.glg.nau.
edu/rcb/ WVU
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Source:http://vishnu.glg.nau.
edu/rcb/ WVU
Gondwanaland: Antarctica, South America, Africa,
Australia and India
Laurasia: North America, Europe,
most of Asia
Source:http://vishnu.glg.nau.edu/rcb/Jur.jpg
Source:http://vishnu.glg.nau.
edu/rcb/ WVU
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Source:http://vishnu.glg.nau.
edu/rcb/ WVU
Source:http://vishnu.glg.nau.
edu/rcb/ WVU
Source:http://vishnu.glg.nau.
edu/rcb/WVU