During the Cretaceous-Paleogene period, approximately 66 million years ago, a catastrophic impact led to an extinction-level event (ELE) that eradicated around three-quarters of Earth’s species, including the dinosaurs. This event is attributed to the Chicxulub meteor, named after the town of Chicxulub Pueblo in Mexico’s Yucatan Peninsula, where the impact crater, measuring 180 kilometers (or 112 miles) in diameter, is located. Recent research has advanced our understanding of the type of meteorite responsible for this historic event.
Identifying the Impacting Meteorite
An international team of scientists has proposed that the impactor may have been a rare type of space rock known as a carbonaceous (CO) chondrite. Their findings, published in Science Advances, stem from an advanced analysis of nickel isotopes in samples collected globally. This research aims to pinpoint the composition of the meteorite that caused the Cretaceous-Paleogene (K–Pg) extinction event.
Methodology and Findings
The study involved high-precision nickel-isotope measurements conducted by postdoctoral researcher Georgy V. Makhatadze and his colleagues at the Institut de Physique du Globe. They analyzed clay samples formed from the impact, which were gathered over several years from various locations. Collaborating institutions included the Vrije Universiteit Brussel, the University of British Columbia, and the University of Vienna.
By comparing the nickel isotopes in the clay layer with those found in other meteorite samples collected over decades, the researchers concluded that the impactor was likely a CO chondrite. This type of meteorite is believed to have originated from the outer Main Asteroid Belt, the Kuiper Belt, or other debris-rich regions of the outer Solar System.
Implications of the Discovery
Carbonaceous chondrites are relatively rare, constituting only 5% of meteorite samples found on Earth, with the Ornans class (CO chondrites) being particularly uncommon. These meteorites are characterized by having significantly lower amounts of volatile elements, such as carbon, zinc, water, and sulfur, compared to other meteorite classes. Dr. Philippe Claeys, a visiting professor at UBC involved in the study, noted that while this discovery does not alter the prevailing theories about the extinction event, it suggests that sulfur from the impactor is less likely to have been the primary factor in the mass extinction.
Despite the remaining questions regarding the origins of the Chicxulub meteorite, this research has significantly narrowed down its classification. The insights gained from this study could be instrumental in predicting future impacts and formulating strategies to protect Earth from similar catastrophic events.
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Original source: universetoday.com
