Music today: The Music today: The Ventures, “Hawaii Five-Ventures, “Hawaii Five-

O”O”

• Reminder: 1st Midterm Exam Reminder: 1st Midterm Exam next Wednesday (April 26)next Wednesday (April 26)

• In class, closed bookIn class, closed book• 70% multiple choice; 30% 70% multiple choice; 30% short essayshort essay

• Study Guide is up on websiteStudy Guide is up on website

Lecture 8: Hotspots, Lecture 8: Hotspots, Plumes and LIPs (Plumes and LIPs (LLarge arge

IIgneous gneous PProvinces)rovinces)

Is Hawaii more than a good vacation spot?Is Hawaii more than a good vacation spot?

How does life respond to catastrophes?How does life respond to catastrophes?

Plate Tectonics - Plate Tectonics - Distribution of Volcanic and Distribution of Volcanic and

Earthquake ActivityEarthquake Activity

Wilson Cycle (ofWilson Cycle (ofocean basin fm)ocean basin fm)

• Examples:Examples:1. East African 1. East African RiftsRifts

2. Red Sea2. Red Sea3. Atlantic Ocean3. Atlantic Ocean4. Pacific Ocean4. Pacific Ocean5. Mediterranean 5. Mediterranean SeaSea

6. Himalayas, Tibet6. Himalayas, Tibet

The Hawaiian HotspotThe Hawaiian Hotspot

Tahiti -- shield volcanoTahiti -- shield volcano

Moorea -- fringing reefMoorea -- fringing reef

Raiatea - barrier reefRaiatea - barrier reef

Bora Bora -- lagoonBora Bora -- lagoon

Maupiti -- the oldest Maupiti -- the oldest volcanovolcano

next stage is the coral next stage is the coral atollatoll

French Polynesia from French Polynesia from spacespace

atollatoll

barrier reefbarrier reeffringing reeffringing reef

VolcanoeVolcanoes to s to

atolls atolls after after DarwinDarwin

Hotspot Volcanic ChainsHotspot Volcanic Chains

Questions:Questions:

• Where do Hotspots come Where do Hotspots come from?from?

• How do Hotspots start?How do Hotspots start?• How long do they last?How long do they last?

Indian OceanIndian Ocean

• Hotspot tracks Hotspot tracks and 3 and 3 spreading spreading ridgesridges

• A complete A complete record of record of hotspot hotspot activityactivity

JOIDES Resolution JOIDES Resolution drillshipdrillship

Western Western IndiaIndia

• An accumulation An accumulation of lava flows 5 of lava flows 5 km thick!km thick!

• Occurred at the Occurred at the same time as same time as the extinction the extinction of the of the dinosaursdinosaurs

Mass Mass ExtinctionExtinction

(K-T (K-T Boundary)Boundary)

• What killed What killed the Dinosaurs?the Dinosaurs?

• 65 million yr 65 million yr agoago

• A meteorite, A meteorite, or volcanic or volcanic activity, or activity, or BOTH?BOTH?

Impact Site:Impact Site: Yucatan Yucatan PeninsulaPeninsula

Volcanic catastrophes and Volcanic catastrophes and Mass ExtinctionsMass Extinctions

GreenlandGreenland

• Birth of the Birth of the Iceland Iceland hotspothotspot

• Next came the Next came the opening of opening of the North the North Atlantic Atlantic Ocean basinOcean basin

Global Distribution of Global Distribution of LIPsLIPs

Large Igneous Large Igneous Provinces are:Provinces are:

• BIG!!BIG!!• NOT explained by Plate NOT explained by Plate TectonicsTectonics

• Initial Plume and Hotspot Initial Plume and Hotspot ActivityActivity

A Mantle A Mantle PlumePlume

• A blob of warm A blob of warm material rising material rising from the lower from the lower mantlemantle

• Solid but Solid but flowing at slow flowing at slow rate (<1 m/yr)rate (<1 m/yr)

Degassing Degassing MagmaMagma

• Gases include Gases include COCO22, SO, SO22, Cl, F , Cl, F that make “acid that make “acid rain”rain”

• Shuts down Shuts down photosynthesisphotosynthesis

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

Hydrothermal Exchange - Hydrothermal Exchange - MetalsMetals

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

Hydrothermal Plumes from LIPsHydrothermal Plumes from LIPs

Effects of Submarine Effects of Submarine PlateausPlateaus

• Release of “reduced” metals Release of “reduced” metals uses up oxygen in the oceansuses up oxygen in the oceans

• Trace metals are “nutrients”, Trace metals are “nutrients”, so promote rapid growth of so promote rapid growth of planktonplankton

• Sinking organic matter also Sinking organic matter also uses up oxygen in the oceansuses up oxygen in the oceans

• Extinctions of marine Extinctions of marine organismsorganisms

Two Styles of Mantle Two Styles of Mantle ConvectionConvection

Evolution of Evolution of LifeLife

• Where there is Where there is chaos there is chaos there is opportunityopportunity

• Extinctions Extinctions lead to new lead to new ecosystemsecosystems