Thursday, December 31, 2009

Asteroid Impact? Yes; Dinosaur-Killing Firestorm? Maybe Not

"Dinosaur-Killing Firestorm Theory Questioned"
Space.com (December 28, 2009)

"New research challenges the idea that the asteroid impact that killed the dinosaurs also sparked a global firestorm.

"Scientists modeled the effect that sand-sized droplets of liquefied rock from the impact had on atmospheric temperature. The asteroid is thought to have gouged out the Chicxulub crater on the Yucat√°n Peninsula in Mexico.

"It was previously thought that the falling spherules, as the tiny rocks are called, heated up the atmosphere by several degrees for up to 20 minutes — hot enough and long enough to cause whole forests to spontaneously burst into flames.

"As evidence for this, scientists pointed to what appears to be carbon-rich soot from burned trees discovered in the thin band of debris dating back to the impact some 65 million years ago, a shift in geologic time called the K-T boundary...."

If the new mathematical model is a closer approximation to what actually happened, the first bits of molten sand slowed down as they fell through the atmosphere, forming an opaque cloud which insulated the surface from (some) of the heat.

It still was a really bad day, followed by quite a number of really bad years.

That soot came from somewhere, though: looks like something caught fire about the same time that the impact happened. One possibility mentioned in the article is petroleum. The area around the Chicxulub impact site is oil-rich today - so the K-T boundary may be evidence of a gargantuan oil field fire.

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