Chapter 9 Flashcards
The two major extiction events on earth have been claimed by some scientists to be caused by what?
Continental Flood Basalts or Continental Flood Basalts
What provides the products of flood basalts?
Superplumes
What is an igneous province?
Large igneous provinces are large volumes of basaltic extrusive (and intrusive)rock that are created by processes other than ‘normal seafloor spreading’.
What are the three features that all igneous plateaus have in common?
- Basalt constitutes almost the entire rock suite. 2. The eruptions were mostly subaerial with only subaqueos conditions. 3. Characteristic is that each plateau was formed within a very short period of time.
What is do igneous plateaus have a correlation with?
Periods of major rifting
What Happened in Iceland in 1783-1784
In Laki, 14.7 cubic sqaure km of basalt flooded out of fissures. It lowered global temperatures by 1 celcius for a year. 80-100 million tons of SULFURIC ACID AEROSOLS were put into the atmosphere.
What is the coverage of the columbia river plateau?
175,000 cubic square kilometers
What is the theory by montana scientists behind the beginning of the columbia river plateau?
Asteroid impact, then basaltic lava flow, then rhyolitic lava eriptions then the yellowstone caldera
Why is a meteor impact the assumed catalyst for the Columbia River Plateau? Is it reasonable? Why?
It was suggested as a primary way that would generate a magma source, however given that it takes something to the order of 1 million years minimum the asteroid impact is not reasonable.
How much of a magma resevoir can be evacuated at one time?
only 10%
What type of rock are the Deccan Traps in India?
Basalts
What dating technique was useless? Why?
K-Ar dating technique, because Ar is gaseous and thus is less likely to be retained in the rock
What present day plume was suggested to have supplied the magma for the Deccan Traps?
The Reunion Islands Plume
What element was found in amounts two orders of magnitude higher in a soil horizion of the Deccan Traps than the Deccan Traps themselves? Where is is suspected the high concentration of this element came from?
Ir or Iridium
How large are the siberian traps?
1.5 Million km squared, represent an eruption of 1.5x10^6 km^3
What was found at the base of the supposedly solid mantle?
Vast blobs of semi-molten rock up to 40km thick and thousands of kilometers wide.
What did researches call the vast blobs of semi-molten rock beneath the earth’s surface?
The “Ultra-Low Velocity Zone”
What is it thought that the poles do in relation to the magma plumes?
Rotate to avoid the most conductive of the plumes.
Was the climate constantly warming across the 250 million year time horizon?
yes
Could the Deccan Traps be responsible for Carbon Dioxide warming the atmosphere?
No
Describe the Mid-Cretaceous Superplume.
120-125 mya a superplume was responsible for doubling the coean floor but not responsible for mass extinction
