Music today: The Ventures,

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Music today The Ventures, Hawaii Five-O

• Reminder 1st Midterm Exam next Wednesday (April
  20)
• In class, closed book
• 70 multiple choice 30 short essay
• Study Guide is up on website

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Lecture 8 Hotspots, Plumes and LIPs (Large
Igneous Provinces)

• Is Hawaii more than a good vacation spot?
• How does life respond to catastrophes?

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Plate Tectonics - Distribution of Volcanic and
Earthquake Activity
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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

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The Hawaiian Hotspot
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Tahiti -- shield volcano
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Moorea -- fringing reef
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Raiatea - barrier reef
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Bora Bora -- lagoon
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Maupiti -- the oldest volcanonext stage is the
coral atoll
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French Polynesia from space

• atoll

fringing reef
barrier reef
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Hotspot Volcanic Chains
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Questions

• Where do Hotspots come from?
• How do Hotspots start?
• How long do they last?

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Indian Ocean

• Hotspot tracks and 3 spreading ridges
• A complete record of hotspot activity

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JOIDES Resolution drillship
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Western India

• An accumulation of lava flows 3 miles thick!
• Occurred at the same time as the dinosaurs
  extinction

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Mass Extinction(K-T Boundary)

• What killed the Dinosaurs?
• 65 million yr ago
• A meteorite, or volcanic activity, or BOTH?

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Impact Site Yucatan Peninsula
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Volcanic catastrophes and Mass Extinctions
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Greenland

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

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Global Distribution of LIPs
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Large Igneous Provinces are

• BIG!!
• NOT explained by Plate Tectonics
• Initial Plume and Hotspot Activity

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A Mantle Plume

• A blob of warm material rising from the lower
  mantle
• Solid but flowing at slow rate (lt1 m/yr)

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Degassing Magma

• Gases include CO2, SO2, Cl, F that make acid
  rain
• Shuts down photosynthesis

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Hydrothermal Exchange - Metals
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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

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Two Styles of Mantle Convection
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Evolution of Life

• Where there is chaos there is opportunity
• Extinctions lead to new ecosystems