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Hotspots, Plumes and Mass Extinctions. Is Hawaii more than a great vacation spot? How does life respond to geologic catastrophes?. Plate Tectonics - Distribution of Volcanic and Earthquake Activity. The Earth’s surface is broken into plates. 1. Wilson Cycle (ocean basin fm). 2. Examples:

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hotspots plumes and mass extinctions

Hotspots, Plumes and Mass Extinctions

Is Hawaii more than a great vacation spot?

How does life respond to geologic catastrophes?

wilson cycle ocean basin fm

1

Wilson Cycle (ocean basin fm)

2

Examples:

1. East African Rifts

2. Red Sea

3. Atlantic Ocean

4. Pacific Ocean

5. Mediterranean Sea

6. Himalayas, Tibet

3

4

5

6

french polynesia from space
French Polynesia from space

atoll

fringing reef

barrier reef

questions
Questions:
  • Where do Hotspots come from?
  • How do Hotspots start?
  • How long do they last?
indian ocean
Indian Ocean
  • Hotspot tracks and 3 spreading ridges
  • A complete record of hotspot activity
western india
Western India
  • An accumulation of lava flows 5 km thick!
  • Occurred at the same time as the extinction of the dinosaurs
mass extinction k t boundary
Mass Extinction(K-T Boundary)
  • What killed the Dinosaurs?
  • 65 million yr ago
  • A meteorite, or volcanic activity, or BOTH?
greenland
Greenland
  • Birth of the Iceland hotspot
  • Next came the opening of the North Atlantic Ocean basin
slide31

red = hotspot-related volcanism since 250 Ma

Columbia River Basin Flood Basalts with source at Yellowstone

Flood basalts, India

large igneous provinces are
Large Igneous Provinces are:
  • BIG!!
  • NOT explained by Plate Tectonics
  • Initial Plume and Hotspot Activity
mantle plumes
Mantle Plumes
  • Part of the circulation in the Mantle
  • Driven by temperature differences
  • Hot and cold => density differences
  • Gravity Rules!http://www.youtube.com/watch?v=f37Gf6IVj6o&feature=related
mantle convection the driving force for plate tectonics
Mantle convection - the driving force for plate tectonics

What causes the warmer material to rise?

mantle convection and hotspot formation

Cross-sections of the Earth

Mantle convection and hotspot formation

Red = hot upwelling from core-mantle

boundary

Blue = cold downwelling

Cold lithosphere sinks, hot plumes rise.

Computer Model

Cartoon Schematic

which is not a hotspot
Which is not a hotspot?

Yellowstone

Iceland

Hawaii

Mt. St. Helens

degassing magma
Degassing Magma
  • Gases include CO2, SO2, Cl, F that make “acid rain”
  • Shuts down photosynthesis
ocean anoxic events productivity or preservation
Ocean Anoxic Eventsproductivity or preservation?

Marine sedimentary layers exposed in Italy

effects of submarine plateaus
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 “benthic” marine organisms
evolution of life
Evolution of Life
  • “Punctuated” by rapid change events
  • Where there is chaos there is opportunity
  • Extinctions lead to new ecosystems