An international research team used advanced nickel isotope analysis of samples to narrow down the composition of the deadly Cretaceous-Palaeogene meteorite. Scientists in Canada, Belgium, France and Austria collaborated on the study, published in the journal Science Advances.
The impactor was around six miles wide and slammed into Earth at an estimated 40,000 mph, forming the massive Chicxulub crater buried underneath the Yucatán Peninsula in Mexico. The team identified it as a rare carbon monoxide chondrite, calling it an 'oddball' meteorite.
Fine debris blamed for mass extinction
Dr. Philippe Claeys, a visiting professor at the University of British Columbia in Canada and a professor at Vrije Universiteit Brussel in Belgium, said: “Carbonaceous chondrites of the Ornans class are definitely not like the typical meteors you find in museum collections. It contains much less volatile elements - like carbon, zinc, water and particularly sulphur - than other classes of meteorites we’ve discovered so far on Earth. It doesn’t alter our theory of what caused the extinction event - but it makes it less likely that sulphur contained in the impactor was the smoking gun. The fine debris thrown into the atmosphere would be the primary factor.”
Researchers in France conducted high-precision nickel isotope measurements of samples collected over years from a thin layer of clay created across the globe by the impact. Dr. Claeys said: “This is challenging work. Only a minute fraction of the projectile is preserved in the planet’s KT clay layer because the entire meteorite vaporised upon impact.”
Rare and primitive material
Carbonaceous chondrites make up only 5% of meteorites so far sampled on Earth. Carbonaceous chondrites of the Ornans class - CO chondrites - make up a tiny fraction of that group. Dr. Claeys says they are some of the most primitive and untouched materials in the solar system. He added: “Being impacted by such a rare, distant projectile really underscores how unlucky the dinosaurs were.”
