To determine the source of the burnt material – black carbon –, the researchers scanned sediments from the Chicxulub crater as well as ocean sediment samples from far from the crater mouth.
Chicxulub crater is the only remnant off the coast of Mexico of a decisive moment in the history of the Earth. The hole runs 93 miles wide and deepest 12 miles into the Earth. It was left by an asteroid or comet — the same one that wiped out 70 percent of living species during the late Cretaceous.
Now, about 66 million years later, burned remains within the crater sediment tell a new story about what actually happened during the dinosaur-eradicating event.
Burned sediment near the Chicxulub crater could hold the key to understanding the conditions that led to mass extinction on earth. Researchers of a new chemical marker studied sediment where evidence of what actually led to the dramatic die-off was found.
The authors of the study reported in the journal Proceedings of the National Academy of Sciences on Monday: “These materials could be derived from wildfires on the land or sedimentary rocks shattered by the asteroid.
To determine the source of the burned material – black carbon –, the researchers studied sediment from the Chicxulub crater as well as ocean sediment samples taken far from the crater mouth. They focused on a group of hydrocarbons referred to as PAHs or polycyclic aromatic hydrocarbons.
Analyzing the chemical composition of the sediments, the researchers found evidence suggesting that black carbon came from a fossil source – not from global fires. The PHA-characteristics suggest that the substance was the product of rapid heating and are consistent with rocks thrown during the asteroid impact.
The samples also contained charcoal — the product of burning biomass as trees.
The results suggest that wildfires did occur after the asteroid hit but they were likely delayed and eventually had a smaller impact on global climate and animal extinctions.