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 SlabPull

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 Pillow Lavas Remember: Melting the mantle makes mafic magma!! Always

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 Crust Recording the Break-up Beginning the Break-up 225 Ma

14. Youthful Oceanic Crust

15. Convergent Boundaries Making 2 nd Stage Crust AncientContinentalCrust

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

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

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 Orogens Looking into the Roots of Mountain Belts Penokean Orogen St. CloudJay Cooke

22. Transform Fault Plate Boundaries

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

24. MantlePlumes/Hotspots

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

26. Famous Hotspots Hawaii Yellowstone 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