Volcanic Eruptions May Have Caused Dinosaur Extinction |
|
Written by spacetravel.org
|
|
Saturday, 20 August 2005 16:35 |
|
The K-T mass extinction that wiped out the dinosaurs about 65 million years ago may have been caused by huge volcanic eruptions in India.
The mass extinction is usually attributed to a 10-kilometre-wide asteroid crashing into the Earth, creating the Chicxulub crater off the coast of Mexico. Some researchers have argued that the volcanic eruptions that formed the Deccan Traps in west-central India contributed to the extinction. However, many scientists have claimed the eruptions did not occur frequently enough to cause such great damage.
Anne-Lise Chenet of the Paris Geophysical Institute in France, and her colleagues from France, India and the UK have now performed research that they believe shows that volcanic eruptions formed the Deccan traps faster than was previously thought. The team drilled cores from the upper 600 meters of the Deccan rock, and found magnetic minerals that would have lined up with the Earths magnetic field at the time the lava was deposited. The team was able to estimate how long each volcanic outburst lasted by comparing these measurements to data on how the Earths magnetic field changed over time. The magnetic dating shows that it took between 12,000 and 27,000 years for a 600-meter-thick slab of lava to be built. The team believes that this rapid outpouring of lava probably injected gases high into the Earths atmosphere, changing the climate catastrophically and leading to the mass extinction.
Many scientists are still doubtful that the eruptions are what caused the dinosaur extinction. Jan Smit from the Free University of Amsterdam believes that the magnetic dating methods that were used are probably not very accurate. Philippe Claeyes from the Free University of Brussels says, the fossil record shows that the extinctions coincide with the impact, rather than the volcanism.
|