Mal wieder ein Ausflug in die Astronomie & die Erdgeschichte. Und nach Kölle.

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Scientists have uncovered the "genetic fingerprint" of the dinosaur-killing Chicxulub impactor, potentially revealing the fateful rock's origins in the outer reaches of our solar system.

The space rock that wiped out the dinosaurs 66 million years ago was a rare strike from an asteroid beyond Jupiter, a new study details. The finding pins down the nature of the fateful space rock and its origin within our solar system, and may benefit technology that forecasts asteroid strikes on our planet.

Most scientists agree that the Chicxulub impactor — named after the community in modern-day Mexico near the 90-mile-wide (145 kilometers) crater carved by the rock — came from within our solar system. But its precise origins remain unclear, due to a lack of clear chemical evidence that wasn't contaminated by Earth's own material. Now, in remnants of the impactor collected from European regions of our planet's crust, scientists have found the chemical composition of a rare element called ruthenium to be similar to that within asteroids hovering between the orbits of Mars and Jupiter.

The element is a "genetic fingerprint" of rocks in the main asteroid belt, where the fateful city-size rock was parked before it struck Earth 66 million years ago, Mario Fischer-Gödde, a scientist at the Institute of Geology and Mineralogy at the University of Cologne in Germany who led the new study, told Live Science. The asteroid was likely nudged toward Earth either by collisions with other space rocks or by influences in the outer solar system, where gas giants like Jupiter harbor immense tidal forces capable of disturbing otherwise stable asteroid orbits.

The findings rely on a new technique that essentially breaks every chemical bond bolstering a rock sample while it is stored in a sealed tube, allowing scientists to measure the specific levels of ruthenium in the Chicxulub impactor. The element has remained remarkably stable over billions of years in the face of Earth's frequent, landscape-recycling geologic activity, said Fischer-Gödde, who developed the new technique over the past decade and is one of just a handful of experts in the world who can precisely analyze the rare element.

The researchers compared the results to samples from other asteroid impact sites in South Africa, Canada and Russia, and also to a couple of carbonaceous meteorites, which dominate the outer region of the main asteroid belt. Ruthenium's chemical signatures in the Chicxulub impactor were consistent only with those of the carbonaceous meteorites, pointing to its origin in the outer solar system, the team reported in a study published Thursday (Aug. 15) in the journal Science.

"The paper presents a fantastic set of isotope analyses," David Kring, a principal scientist at the Lunar and Planetary Institute in Texas who was part of the team that linked the Chicxulub impact crater to the dinosaur-killing asteroid decades ago and was not involved with the new study, told Live Science. "You need to understand the origin of objects like this if you're going to properly assess future hazards."

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https://www.space.com/asteroid-chicxulub...rce=twitter.com

"Ruthenium isotopes show the Chicxulub impactor was a carbonaceous-type asteroid"

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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.

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https://www.science.org/doi/10.1126/scie...TS%3D1723710683


Autoren
Mario Fischer-Gödde, Institut für Geologie und Mineralogie, University of Cologne, 50674 Cologne, Germany.
Jonas Tusch, Institut für Geologie und Mineralogie, University of Cologne, 50674 Cologne, Germany.
Steven Goderis, Archeology, Environmental Changes and Geochemistry Research Group, Vrije Universiteit Brussel, 1050 Brussels, Belgium.
Alessandro Bragagni, Department of Earth Sciences, University of Florence
Tanja Mohr-Westheide, Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, 10115 Berlin
Nils Messling, Geochemistry and Isotope Geology Department, Geoscience Center, University of Göttingen, 37073 Göttingen
Bo-Magnus Elfers, Zentrallabor, Technical University Hamburg, 21073 Hamburg
Birger Schmitz, Astrogeobiology Laboratory, Lund University, SE-22100 Lund, Sweden.
Wolf U. Reimold, Laboratório de Geocronologia e Geoquímica Isotópica, Instituto de Geociências, Universidade de Brasília, CEP 70910-900 Brasília
Wolfgang D. Maier, School of Earth and Ocean Sciences, Cardiff University, Cardiff CF10 3AT, UK.
Philippe Claeys, Archeology, Environmental Changes and Geochemistry Research Group, Vrije Universiteit Brussel, 1050 Brussels
Christian Koeberl, Department of Lithospheric Research, University of Vienna, A-1090 Vienna, Austria,
François L. H. Tissot, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena CA 91125, USA.
Martin Bizzarro, Center for Star and Planet Formation, Globe Institute, University of Copenhagen, DK-1350 Copenhagen, Denmark
Carsten Münker, Institut für Geologie und Mineralogie, University of Cologne, 50674 Cologne, Germany.