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Earth History GEOL 2110

Earth History GEOL 2110. Theory of Plate Tectonics Part 2: Elements of Plate Tectonics. Major Concepts.

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Earth History GEOL 2110

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  1. Earth History GEOL 2110 Theory of Plate Tectonics Part 2: Elements of Plate Tectonics

  2. Major Concepts • Plate Tectonic theory posits that the earth outer layer (lithosphere) is composed of rigid plates that are moving relative to each other; Plates are composed of either thin oceanic crust or thick continental crust overlying upper mantle • Plate boundaries that are diverging are where new oceanic crust is being created as the mantle upwells, decompresses and partially melts. • Plate boundaries that are converging involve one oceanic crust plate subducting beneath another or a continental edge. This triggers earthquakes and explosive volcanism resulting from partial melting of a hydrated mantle wedge • Orogensis occurs when continental crust encounters continental crust

  3. Plate Tectonic Theory The Earth’s outer shell (lithosphere) is composed of rigid plates that are moving relative to one another.

  4. Internal Structure of the Earth Compositional Layers Physical Layers

  5. Plate Tectonics Drives Two Stages Crust-making A. Mantle partially melts to make ocean crust B. Ocean crust partially melts to make continental crust

  6. What Moves the Plates? Mantle Push Ridge Slide Slab Pull

  7. Types of Plate Boundaries

  8. Divergent Plate Boundaries Mid-ocean Ridges Where Stage 1 Crust is Made

  9. Basalt Rock Type of the Ocean Crust Remember: Melting the mantle makes mafic magma!! Always Pillow Lavas

  10. Hydrothermal Alteration of Ocean Crust Preparing it for Stage 2 Melting “Black Smokers”- metal-rich hydrothermal waters venting into the ocean floor

  11. Continental Rifting The creation of new ocean basins

  12. Continental Rifting and The Break-up of Pangea

  13. Age of the Atlantic Ocean CrustRecording the Break-up Beginning the Break-up 225 Ma

  14. Youthful Oceanic Crust

  15. Convergent Boundaries Making 2nd Stage Crust Ancient Continental Crust

  16. Convergent Boundaries Where the Action Is!! Ocean - Ocean Earthquakes Ocean- Continent Volcanoes Continent - Continent

  17. Consequences of Convergence Explosive Volcanism Mt. St. Helens May 18, 1980

  18. Consequences of Convergence Mountain Building and Rock Deformation

  19. Consequences of Convergence Earthquakes Banda Ache, Dec. 26, 2004

  20. OROGENESIS The Culmination of Convergence

  21. Ancient OrogensLooking into the Roots of Mountain Belts Jay Cooke St. Cloud PenokeanOrogen

  22. Transform Fault Plate Boundaries

  23. The San Andreas Fault San Francisco Earthquake April 18, 1906 Mag 7.8

  24. Mantle Plumes/ Hotspots

  25. Mantle Hotspots in the Oceans Sites of overthickened crust and the formation of ocean islands and plateaus

  26. Famous Hotspots Yellowstone Hawaii Iceland

  27. Sedimentary Basins and Plate Tectonics Evolution of Sedimentation during Arc-Continent Collision

  28. The Grand Unifying Theory of the Earth

  29. FRIDAY Midterm Exam 1 Chapters 1 to 7

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