A team of VUB geologists examined the boundary layer between the Cretaceous and Paleogene periods in the study. This boundary layer formed in the composition of the Earth’s surface 66 million years ago as a result of a meteorite impact that caused the extinction of 70 percent of the animals living at the time, including dinosaurs.
The asteroid, which was more than 10 kilometers in diameter, hit near where the Mexican city of Chicxulub is located today. The impact was so powerful that a layer of mud formed over the entire Earth as a result of the dust particles emitted.
This K-Pg boundary layer contains elements that are found only exceptionally well on the Earth’s surface, including osmium, iridium, and ruthenium.
A unique event
Analysis of the chemical elements in the clay layer shows that Chicxulub comes from the outer solar system. “We found that the composition of the asteroid that struck Chicxulub is similar to carbonaceous meteorites,” said Stephen Gooderes, one of the study’s authors. These C-type asteroids “originally formed outside the orbit of Jupiter.”
The exceptional nature of the Chicxulub meteorite is also demonstrated by comparisons of chemical elements from other layers of the Earth’s surface. “These data show that over the past 500 million years, the dominant compositions of objects impacting the Earth have been fragments of stony S-type asteroids,” the geologists said.
This type of asteroid forms in the inner solar system. “The impact of a C-type asteroid appears to be a unique event so far.”
