Scientists finally identify rare type of asteroid that wiped out dinosaurs
The secret of the killer asteroid revealed (photo: Pexels)
An international team of scientists led by the University of British Columbia has identified the exact chemical class of the asteroid that caused the extinction of the dinosaurs 66 million years ago, according to Futura.
Isotopic fingerprint of the Chicxulub asteroid
Because the 10–15-kilometer-wide asteroid completely vaporized when it struck Earth at a speed of 64,000 km/h, researchers studied samples from the global Cretaceous-Paleogene (K-Pg) boundary layer, including clay deposits from the Stevns Klint geological section in Denmark.
By measuring the ratio of stable nickel isotopes in the iridium-rich layer, geochemists determined that the space rock belonged to a rare class of carbonaceous chondrites known as CO (Ornans) chondrites.
Carbonaceous chondrites account for only about 5% of all meteorites found on Earth, while the CO subtype represents just a tiny fraction of this group.
Rethinking the mechanism behind global cooling
CO-type parent rocks are among the most primitive materials in the Solar System, but they are poor in volatile elements such as carbon, zinc, water and sulfur.
The discovery changes our understanding of the factors behind the climate collapse:
Less cosmic sulfur: The asteroid brought far less sulfur to Earth than previous climate models had assumed.
Earth’s rocks played a key role: Vaporized rocks from Mexico’s Yucatán Peninsula and fine silicate dust became the main factors blocking sunlight and causing prolonged cooling.
A shift in scientific models: The catastrophic effects were caused primarily by terrestrial rocks blasted into the atmosphere rather than the asteroid’s own chemical composition.
The asteroid’s CO classification also suggests that it formed in a distant region of the Solar System near Jupiter.
Its collision with Earth was an extremely rare combination of gravitational disturbances and orbital trajectories.
