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Exploring Hawaii's Geological Wonders

Delve into Hawaii's volcanic and geologic history. Learn about hotspots, LIPs, and more. Study material for upcoming exam. Discover the mysteries of mantle convection and mass extinctions. Unravel the effects of volcanic catastrophes on marine life.

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Exploring Hawaii's Geological Wonders

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  1. Music today: The Ventures, “Hawaii Five-O” • Reminder: 1st Midterm Exam next Wednesday (April 26) • In class, closed book • 70% multiple choice; 30% short essay • Study Guide is up on website

  2. Lecture 8: Hotspots, Plumes and LIPs (Large Igneous Provinces) Is Hawaii more than a good vacation spot? How does life respond to catastrophes?

  3. Plate Tectonics - Distribution of Volcanic and Earthquake Activity

  4. Wilson Cycle (ofocean basin fm) • Examples: 1. East African Rifts 2. Red Sea 3. Atlantic Ocean 4. Pacific Ocean 5. Mediterranean Sea 6. Himalayas, Tibet

  5. The Hawaiian Hotspot

  6. Tahiti -- shield volcano

  7. Moorea -- fringing reef

  8. Raiatea - barrier reef

  9. Bora Bora -- lagoon

  10. Maupiti -- the oldest volcanonext stage is the coral atoll

  11. French Polynesia from space atoll fringing reef barrier reef

  12. Volcanoes to atolls after Darwin

  13. Hotspot Volcanic Chains

  14. Questions: • Where do Hotspots come from? • How do Hotspots start? • How long do they last?

  15. Indian Ocean • Hotspot tracks and 3 spreading ridges • A complete record of hotspot activity

  16. JOIDES Resolution drillship

  17. Western India • An accumulation of lava flows 5 km thick! • Occurred at the same time as the extinction of the dinosaurs

  18. Mass Extinction(K-T Boundary) • What killed the Dinosaurs? • 65 million yr ago • A meteorite, or volcanic activity, or BOTH?

  19. Impact Site: Yucatan Peninsula

  20. Volcanic catastrophes and Mass Extinctions

  21. Greenland • Birth of the Iceland hotspot • Next came the opening of the North Atlantic Ocean basin

  22. Global Distribution of LIPs

  23. Large Igneous Provinces are: • BIG!! • NOT explained by Plate Tectonics • Initial Plume and Hotspot Activity

  24. A Mantle Plume • A blob of warm material rising from the lower mantle • Solid but flowing at slow rate (<1 m/yr)

  25. Degassing Magma • Gases include CO2, SO2, Cl, F that make “acid rain” • Shuts down photosynthesis

  26. Laki, Iceland (1783) -- the year without a summer

  27. Hydrothermal Exchange - Metals

  28. Ocean Anoxic Events (OAEs)productivity or preservation?

  29. Hydrothermal Plumes from LIPs

  30. Effects of Submarine Plateaus • Release of “reduced” metals uses up oxygen in the oceans • Trace metals are “nutrients”, so promote rapid growth of plankton • Sinking organic matter also uses up oxygen in the oceans • Extinctions of marine organisms

  31. Two Styles of Mantle Convection

  32. Evolution of Life • Where there is chaos there is opportunity • Extinctions lead to new ecosystems

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