Researchers Narrow Down Type of Meteorite That Caused Dinosaur Extinction

• A recent study using high-precision nickel isotope analysis identifies the Chicxulub impactor as a rare carbonaceous chondrite (CO chondrite).
• The impact, occurring 66 million years ago, triggered the Cretaceous-Paleogene (K–Pg) extinction event by ejecting massive amounts of debris into the atmosphere.
• Researchers suggest the meteorite likely originated from the outer Solar System, such as the outer Main Asteroid Belt or the Kuiper Belt.

Impact Analysis

• An international research team, including scientists from Institut de Physique du Globe, VUB, UBC, and the University of Vienna, analyzed clay samples from the K–Pg boundary found globally.
• The team compared nickel isotope signatures in these samples to known meteorites to determine the impactor's composition.
• The findings indicate the meteor was an Ornans-class (CO) chondrite, a highly primitive type representing only 5% of recovered meteorites.

Scientific Implications

• The study challenges the hypothesis that sulfur from the meteorite was the primary driver of the resulting global climate cooling.
• Dr. Philippe Claeys noted that CO chondrites contain fewer volatile elements, such as sulfur, compared to other known types, suggesting that fine debris ejected by the collision was the main factor in blocking sunlight and creating a "nuclear winter."
• These insights help improve models for predicting and defending Earth against potential future asteroid impacts.