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Xinhua News Agency, Beijing, August 19th. An international research team recently published a paper in the American magazine Science, saying that through the analysis of sediments in the Chicxulub area of ​​Mexico, they believe that the object that hit the Earth about 66 million years ago and caused the extinction of non-avian dinosaurs was a carbonaceous asteroid from the outer solar system.

Previous studies generally believe that the impact in the Chicxulub area and the corresponding changes in the earth's environment led to a mass extinction, including the extinction of non-avian dinosaurs. However, there are still many unsolved questions about the nature of the impactor.

Researchers from the University of Cologne and other institutions in Germany collected rock samples at three locations in the Chicxulub crater. Test results showed that the samples were rich in metal elements such as iridium, ruthenium, and platinum. These metal elements are rare on Earth but very common on asteroids. In the process of analyzing the ratio of ruthenium isotopes, the researchers found clues about the source of the impactor.

Ruthenium has seven stable isotopes, with different mixed characteristics in celestial bodies from different sources. By comparing the sample data with rock samples from eight other impact sites in the past 3.5 billion years, the research team found that the ruthenium isotope characteristics left at the Chicxulub impact site do not match those of siliceous asteroids from the inner solar system, but are very consistent with carbonaceous asteroids from the outer solar system.

It was once believed that the impactor was part of a comet that disintegrated under the gravitational pull of the sun. However, the team conducting this study believes that the ruthenium isotope data of the comet fragments do not match the characteristics of the impact site. (End)