Fischer-Gödde Mario, Tusch Jonas, Goderis Steven, Bragagni Alessandro, Mohr-Westheide Tanja, Messling Nils, Elfers Bo-Magnus, Schmitz Birger, Reimold Wolf U, Maier Wolfgang D, Claeys Philippe, Koeberl Christian, Tissot François L H, Bizzarro Martin, Münker Carsten
Institut für Geologie und Mineralogie, University of Cologne, 50674 Cologne, Germany.
Archeology, Environmental Changes and Geochemistry Research Group, Vrije Universiteit Brussel, 1050 Brussels, Belgium.
Science. 2024 Aug 16;385(6710):752-756. doi: 10.1126/science.adk4868. Epub 2024 Aug 15.
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.
6600万年前，墨西哥希克苏鲁伯发生了一次撞击事件，形成了一个全球地层，标志着白垩纪和古近纪的界限。该地层中铂族元素（包括钌）的浓度升高。我们测量了取自三个白垩纪-古近纪边界地点、其他五个发生在3600万至4.7亿年前的撞击事件以及古老的35亿至32亿年前撞击球粒层的样本中的钌同位素。我们的数据表明，希克苏鲁伯撞击体是一颗碳质小行星，它形成于木星轨道之外。其他五个撞击结构的同位素特征与在更靠近太阳的位置形成的硅质小行星更为一致。古老的球粒层样本与地球吸积最后阶段碳质小行星的撞击情况相符。
