Ruthenium isotopes show the Chicxulub impactor was a carbonaceous-type asteroid
Mario Fischer‐Gödde, Jonas Tusch, Steven Goderis, Alessandro Bragagni, T. Mohr‐Westheide, Nils Meßling, Bo-Magnus Elfers, Birger Schmitz, W. U. Reimold, W. D. Maier, Philippe Claeys, Christian Koeberl, François Tissot, Martin Bizzarro, Carsten Münker
Abstract
An impact at Chicxulub, Mexico, occurred 66 million years ago, producing a global stratigraphic layer that marks the boundary between the Cretaceous and Paleogene eras. That layer contains elevated concentrations of platinum-group elements, including ruthenium. We measured ruthenium isotopes in samples taken from three Cretaceous-Paleogene boundary sites, five other impacts that occurred between 36 million to 470 million years ago, and ancient 3.5-billion- to 3.2-billion-year-old impact spherule layers. Our data indicate that the Chicxulub impactor was a carbonaceous-type asteroid, which had formed beyond the orbit of Jupiter. The five other impact structures have isotopic signatures that are more consistent with siliceous-type asteroids, which formed closer to the Sun. The ancient spherule layer samples are consistent with impacts of carbonaceous-type asteroids during Earth's final stages of accretion.