Asteroid That Wiped Out Dinosaurs Came from Beyond Jupiter

Asteroid That Wiped Out Dinosaurs Came from Beyond Jupiter
by Robert Schreiber
Berlin, Germany (SPX) Aug 16, 2024

Scientists have determined that the asteroid responsible for the mass extinction event 66 million years ago was a rare carbonaceous asteroid originating from beyond Jupiter. This discovery clarifies long-standing debates regarding the Chicxulub impactor and offers new insights into Earth's geological history and the extraterrestrial objects that have impacted it.

The Earth has experienced several mass extinction events, with the most recent occurring 66 million years ago at the Cretaceous-Paleogene (K-Pg) boundary. This event, which led to the extinction of around 60% of Earth's species, including non-avian dinosaurs, is believed to have been triggered by the Chicxulub impactor-a massive asteroid that struck what is now the Gulf of Mexico. Elevated levels of platinum-group elements (PGEs), such as iridium, ruthenium, osmium, rhodium, platinum, and palladium, found in K-Pg boundary layers worldwide, support the asteroid impact theory. These elements are rare on Earth but common in meteorites, indicating that the impact caused debris to spread globally.

Some scientists have suggested that volcanic activity from the Deccan Traps could be an alternative source of these PGEs. However, the specific ratios of PGEs at the K-Pg boundary align more closely with those resulting from asteroid impacts rather than volcanic activity. Despite this, details about the composition and origin of the Chicxulub impactor have remained elusive until now.

To investigate further, Mario Fischer-Godde and his research team analyzed ruthenium (Ru) isotopes in samples taken from the K-Pg boundary. They also examined samples from five other asteroid impact sites dating back 541 million years, ancient Archaean-age impact-related spherule layers (3.5 - 3.2 billion years old), and two carbonaceous meteorites for comparison.

The findings showed that the Ru isotope signatures in K-Pg boundary samples closely matched those of carbonaceous chondrites (CCs), differing from Earth or other types of meteorites. This suggests that the Chicxulub impactor likely originated from a C-type asteroid formed in the outer Solar System.

Additionally, the study ruled out the possibility of a comet being the impactor. Ancient Archean samples also indicate that similar CC-like material impacted Earth during its final stages of accretion. In contrast, other impact sites from different periods displayed Ru isotope compositions consistent with S-type (silicaceous) asteroids from the inner Solar System.

Research Report:Ruthenium isotopes show the Chicxulub impactor was a carbonaceous-type asteroid