Music today: The Ventures, “Hawaii Five-O” Reminder: 1st Midterm Exam next Wednesday (April 20) Reminder: 1st Midterm Exam next Wednesday (April 20) In class, closed book In class, closed book 70% multiple choice; 30% short essay 70% multiple choice; 30% short essay Study Guide is up on website Study Guide is up on website

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

Plate Tectonics - Distribution of Volcanic and Earthquake Activity

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

The Hawaiian Hotspot

Tahiti -- shield volcano

Moorea -- fringing reef

Raiatea - barrier reef Raiatea - barrier reef

Bora Bora -- lagoon

Maupiti -- the oldest volcano next stage is the coral atoll

French Polynesia from space atoll barrier reef fringing reef

Hotspot Volcanic Chains

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

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

JOIDES Resolution drillship

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

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

Impact Site: Yucatan Peninsula

Volcanic catastrophes and Mass Extinctions

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

Global Distribution of LIPs

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

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

Degassing Magma Gases include CO 2, SO 2, Cl, F that make “acid rain” Gases include CO 2, SO 2, Cl, F that make “acid rain” Shuts down photosynthesis Shuts down photosynthesis

Hydrothermal Exchange - Metals

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

Two Styles of Mantle Convection

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