© University of California Observatories/Don DavisAn artist's image of an asteroid Impact.
All over the Earth, there is a buried layer of sediment rich in iridium called the
Cretaceous Paleogene-Boundary (K-Pg.) This sediment is the global signature of the 10-km-diameter asteroid that killed off the dinosaurs—and about 50% of all other species—66 million years ago.
Now, in an effort to understand how life recovered after that event, scientists are going to drill down into the site where the asteroid struck—the Chicxulub Crater off the coast of Mexico's Yucatan Peninsula.The end-Cretaceous extinction was a global catastrophe, and a lot is already known about it. We've learned a lot about the physical effects of the strike on the impact area from oil and gas drilling in the Gulf of Mexico. According to data from that drilling, released on February 5th in the
Journal of Geophysical Research: Solid Earth, the asteroid that struck Earth displaced approximately 200,000 cubic km (48,000 cubic miles) of sediment. That's enough to fill the largest of the Great Lakes—Lake Superior—17 times.
The Chicxulub impact caused earthquakes and tsunamis that first loosened debris, then swept it from nearby areas like present-day Florida and Texas into the Gulf basin itself. This layer is hundreds of meters thick, and is hundreds of kilometers wide. It covers not only the Gulf of Mexico, but also the Caribbean and the Yucatan Peninsula.
In April, a team of scientists from the University of Texas and the National University of Mexico will spend two months drilling in the area, to gain insight into how life recovered after the impact event. Research Professor Sean Gulick of the University of Texas Institute for Geophysics told CNN in an interview that the team already has a hypothesis for what they will find. "We expect to see a period of no life initially, and then life returning and getting more diverse through time."
Scientists have been wanting to drill in the impact region for some time, but couldn't because of commercial drilling activity. Allowing this team to study the region directly will build on what is already known: that this enormous deposit of sediment happened over a very short period of time, possibly only a matter of days. The drilling will also help paint a picture of how life recovered by looking at the types of fossils that appear. Some scientists think that the asteroid impact would have lowered the pH of the oceans, so the fossilized remains of animals that can endure greater acidity would be of particular interest.
The Chicxulub impact was a monumental event in the history of the Earth, and it was extremely powerful. It may have been a billion times more powerful than the atomic bomb dropped on Hiroshima. Other than the layer of sediment laid down near the site of the impact itself, its global effects probably included widespread forest fires, global cooling from debris in the atmosphere, and then a period of high temperatures caused by an increase in atmospheric CO2.
We already know what will happen if an asteroid this size strikes Earth again—global devastation. But drilling in the area of the impact will tell us a lot about how geological and ecological processes respond to this type of devastation.
Interesting article. I wonder how deep they plan to drill?
I still don't understand how CO2 can be the contributing factor for elevated temperatures on Earth. If the CO2 came from the burning of organic matter then the sky would be filled with soot and the surface of the Earth would be cool due to lack of sunlight, as the article suggests. To suggest that subsequent warming was caused by CO2 does not make sense.
Why? CO2 has a molecular weight of 44.01 while air is about 28, which means the CO2 would not sit long in the atmosphere. H2O is many, many times more efficient than CO2 as a 'greenhouse' gas and even today there is far more water in our atmosphere than CO2. 10,000 ppm water vs. 400 ppm CO2.
I could see warming caused by an increase in atmospheric water vapor resulting from the impact and subsequent fires but no CO2.