1 / 38

Plate Tectonics

Plate Tectonics. Chapter 3, part 2. Last Time. Expanding Earth Contracting Earth Continental drift hypothesis Sea floor spreading. What drives plate movement?. Late 1900’s : Plate tectonics Crust: cold, rigid Mantle: hotter, behaves plastically. What drives plate movement?.

vasilis
Download Presentation

Plate Tectonics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Plate Tectonics Chapter 3, part 2

  2. Last Time • Expanding Earth • Contracting Earth • Continental drift hypothesis • Sea floor spreading

  3. What drives plate movement? • Late 1900’s: Plate tectonics • Crust: cold, rigid • Mantle: hotter, behaves plastically

  4. What drives plate movement? • Ultimately: heat transported from core and mantle to surface • Heat transported by convection • Core is ~5,000°C and surface is ~0°C • Mantle convection creates a conveyor belt in mantle • Crust dragged along on top

  5. Plate movement with convection • Where mantle rises: rifting • Where mantle dives: subduction zones

  6. Theory of plate tectonics • Crust made of rigid plates • Ocean plates: thin and dense • Continental: thicker, less dense • Plates are moving on top of mantle

  7. Theory of plate tectonics • Crust made of rigid plates • Ocean plates: thin and dense • Continental: thicker, less dense • Plates are moving on top of mantle • Plates separate and collide

  8. Types of plate boundaries • Divergent: plates move apart • Convergent: plates collide • Transform: plates slide by each other

  9. Divergent Plate boundaries • A.k.a. spreading ridges

  10. Evidence of divergent plate boundary in oceans • Pillow lavas of basalt along mid-Atlantic ridge

  11. Beginning of continental rifting

  12. Mid-stage of rifting

  13. Ultimate goal of rifting

  14. Ultimate goal of rifting

  15. Modern divergent plate boundaries

  16. Convergent plate margins • 2 plates meet head on

  17. Ocean-ocean convergence • One plate dives down (subducts) below other plate • Volcanoes form above subduction zone • Basalts • Volcanic island arc

  18. Ocean-ocean convergence • One plate dives down (subducts) below other plate • Volcanoes form above subduction zone • Basalts • Volcanic island arc • Aleutians, Japan etc.

  19. Convergent plate boundaries • Ocean-continent convergence • Ocean plate subducts below continent

  20. Ocean-continent convergent margin • Melting forms volcanoes above subduction zone • Forms rhyolites, andesites

  21. Ocean-continent convergent margin • Melting forms volcanoes above subduction zone • Forms rhyolites, andesites • Cascades, Andes

  22. Continent-continent convergence • Neither plate wants to subduct • Lots of metamorphic rocks, lots of folds, high mountains

  23. Continent-continent convergence • Neither plate wants to subduct • Lots of metamorphic rocks, lots of folds, high mountains • Himalaya, Alps

  24. How to recognize ancient subduction zone? • Volcanic rocks, andesites • Deformed ocean sedimentary rocks

  25. Transform plate margin • 2 plates slide past each other

  26. Transform boundary and earthquakes • The division between two blocks is called a fault • Strain builds up in rocks due to friction • Rocks rupture releasing strain in the form of earthquake energy

  27. Transform boundary and earthquakes • The division between two blocks is called a fault • Strain builds up in rocks due to friction • Rocks rupture releasing strain in the form of earthquake energy

  28. Transform boundary on ocean floor

  29. Transform boundary on ocean floor

  30. Transform plate boundary:San Andreas fault

  31. San AndreasFault

  32. How to recognize ancient transform boundaries • Broken, ruptured rock • Adjacent rock units that shouldn’t be next to each other

  33. How are plate movements determined? • Satellite/GPS • Age of ocean floor, distance from spreading ridge • Distance= rate x time

  34. 3 main types of plate boundaries

  35. Plate tectonics • Controls where mountains are built • Controls where earthquakes are • Controls biologic world (climate, geographic barriers)

  36. Plate tectonics homework 3 PM Friday • Scavenger hunt by 3 PM Wednesday • Potential test question today • Name • Question from tectonics or rocks lectures you want to see on the first test.

  37. Where are earthquakes? • Transform boundaries • Subduction zones • Areas of active mountain building

  38. Where are areas of active mountain building? • Collision zones between plates • Volcanoes, earthquakes, deformed rocks

More Related