Global fires after the asteroid impact probably caused the K-Pg extinction

Mar 26, 2013

About 66 million years ago a mountain-sized asteroid hit what is now the Yucatan in Mexico at exactly the time of the Cretaceous-Paleogene (K-Pg) mass extinction. Evidence for the asteroid impact comes from sediments in the K-Pg boundary layer, but the details of the event, including what precisely caused the mass extinction, are still being debated.

Some scientists have hypothesized that since the ejecta from the impact would have heated up dramatically as it reentered the Earth's atmosphere, the resulting from the would have ignited fires around the globe and killed everything except those animals and plants that were sheltered underground or underwater.

Other scientists have challenged the global fire hypothesis on the basis of several lines of evidence, including absence of charcoal-which would be a sign of widespread fires-in the K-Pg boundary sediments. They also suggested that the soot observed in the debris layer actually originated from the impact site itself, not from widespread fires caused by reentering ejecta.

Robertson et al. show that the apparent lack of charcoal in the K-Pg boundary layer resulted from changes in sedimentation rates: When the charcoal data are corrected for the known changes in sedimentation rates, they exhibit an excess of charcoal, not a deficiency. They also show that the mass of soot that could have been released from the impact site itself is far too small to account for the observed soot in the K-Pg layer. In addition, they argue that since the physical models show that the radiant energy reaching the ground from the reentering ejecta would be sufficient to ignite tinder, it would thereby spark widespread fires. The authors also review other evidence for and against the firestorm hypothesis and conclude that all of the data can be explained in ways that are consistent with widespread fires.

Explore further: New study confirms water vapor as global warming amplifier

More information: K/Pg extinction: Reevaluation of the heat/fire hypothesis, Journal of Geophysical Research-Planets, doi:10.1002/jgrg.20018 , 2013. http://onlinelibrary.wiley.com/doi/10.1002/jgrg.20018/abstract

add to favorites email to friend print save as pdf

Related Stories

When dinosaurs roamed a fiery landscape

Mar 29, 2012

The dinosaurs of the Cretaceous may have faced an unexpected hazard: fire! In a paper published online today, researchers from Royal Holloway University of London and The Field Museum of Natural History in Chicago have shown ...

Rutgers scientists: Asteroids did kill the dinosaurs

Nov 29, 2010

(PhysOrg.com) -- Sometimes, you just can’t trust the iridium. A silvery-white natural metal that’s a member of the platinum family, iridium is a key ingredient in the manufacture of spark plugs. ...

New Blow for Dinosaur-Killing Asteroid Theory

Apr 27, 2009

(PhysOrg.com) -- The enduringly popular theory that the Chicxulub crater holds the clue to the demise of the dinosaurs, along with some 65 percent of all species 65 million years ago, is challenged in a paper ...

Recommended for you

Huge waves measured for first time in Arctic Ocean

11 hours ago

As the climate warms and sea ice retreats, the North is changing. An ice-covered expanse now has a season of increasingly open water which is predicted to extend across the whole Arctic Ocean before the middle ...

New research reveals Pele is powerful, even in the sky

17 hours ago

One might assume that a tropical storm moving through volcanic smog (vog) would sweep up the tainted air and march on, unchanged. However, a recent study from atmospheric scientists at the University of Hawai'i ...

Image: Wildfires continue near Yellowknife, Canada

17 hours ago

The wildfires that have been plaguing the Northern Territories in Canada and have sent smoke drifting down to the Great Lakes in the U.S. continue on. NASA's Aqua satellite collected this natural-color image ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

Sherrin
1 / 5 (1) Mar 27, 2013
The K-Pg boundary? Why do scientists always do this to us?? Last I heard, for many years this boundary was termed the K-T boundary (Cretaceous-Tertiary). What's wrong with keeping the original terminology?
Lumberjack
not rated yet Apr 10, 2013
The K-Pg boundary? Why do scientists always do this to us?? Last I heard, for many years this boundary was termed the K-T boundary (Cretaceous-Tertiary). What's wrong with keeping the original terminology?

Tertiary, Secondary and Quaternary have been officially deprecated by the International Commission on Stratigraphy