Tracking down the asteroid that sealed the fate of the dinosaurs
If there is anything guaranteed to have creationists metaphorically, if not actually, screwing up their eyes, putting their hands over their ears and jumping up and down shouting "'Tisn't! 'Tisn't! 'Tisn't!" its news about the mass extinction 66 million years before 'Creation Week' that exterminated all but the non-avian dinosaurs and the early mammals and about 75% of all other species.
This event reminds them not only that Earth is very much older that their cult requires them to believe but also that Earth is not the 'finely-tuned' haven for life that their belief in a perfect creator requires them to believe. Instead, Earth is very old and subject to unpredictable catastrophes, not the least of which are cosmological events such as meteor strikes and the consequential mass extinctions.
Please outline the main consequences of the impact at Chicxulub, Mexico, 66 million years ago, and how we know about them. The impact at Chicxulub, Mexico, 66 million years ago, had profound and far-reaching consequences on Earth's environment and life, leading to the mass extinction event that wiped out approximately 75% of all species, including the non-avian dinosaurs. Here’s an outline of the main consequences and how we know about them:Now a team of Geoscientists from the University of Cologne have led an international study to determine the origin of the huge piece of rock that hit the Earth around 66 million years ago and permanently changed the climate. They have discovered that the meteor was unusual in that it came from a region of space outside the orbit of Jupiter. They have just published their findings in the journal Science and announced it in a University of Cologne Press release:
Main Consequences of the Chicxulub Impact
How We Know About These Consequences
- Immediate Devastation
- Impact and Shockwaves: The asteroid, about 10-15 kilometers in diameter, struck with a force equivalent to billions of atomic bombs. This caused massive shockwaves, earthquakes, and tsunamis that devastated the immediate region and beyond.
- Vaporization of Rock and Ejecta: The impact vaporized rock and blasted debris high into the atmosphere, forming a crater over 150 kilometers wide.
- Global Climate Effects
- Soot and Aerosols in the Atmosphere: The impact ejected vast quantities of dust, soot, and sulfur aerosols into the atmosphere, blocking sunlight for months to years. This led to a dramatic drop in global temperatures, known as an "impact winter."
- Wildfires: The intense heat from the impact likely ignited wildfires worldwide, adding more soot to the atmosphere and exacerbating the cooling effect.
- Ocean Acidification: The release of sulfur and carbon dioxide into the atmosphere led to acid rain, which acidified the oceans and disrupted marine ecosystems.
- Mass Extinction
- Collapse of Food Chains: The prolonged darkness and cooling caused a collapse in photosynthesis, leading to the failure of food chains both on land and in the oceans.
- Selective Extinctions: Large animals, particularly non-avian dinosaurs, were unable to survive the rapid environmental changes, while smaller, more adaptable species had better survival rates. This event is linked to the Cretaceous-Paleogene (K-Pg) mass extinction.
Conclusion
- Geological Evidence
- Chicxulub Crater: The Chicxulub crater on the Yucatán Peninsula was discovered in the late 20th century and is now widely accepted as the impact site. Its size and age correspond with the K-Pg boundary.
- K-Pg Boundary Layer: A thin layer of clay enriched with iridium, a rare element on Earth's surface but common in asteroids, is found globally at the K-Pg boundary. This layer also contains shocked quartz and spherules, indicating a massive impact.
- Paleontological Evidence
- Fossil Record: The fossil record shows a sharp decline in species diversity at the K-Pg boundary. The sudden disappearance of many species, including all non-avian dinosaurs, is consistent with a rapid, catastrophic event.
- Changes in Marine Microfossils: Studies of marine microfossils, such as foraminifera, show a dramatic reduction in diversity at the K-Pg boundary, supporting the idea of a sudden environmental disruption.
- Climate Models and Simulations
- Impact Winter: Climate models simulate the global cooling effect of an impact winter, showing how sunlight could have been blocked for extended periods, leading to the observed mass extinction patterns.
- Ocean Acidification: Models also suggest that the release of sulfur dioxide and carbon dioxide would have led to ocean acidification, which is supported by chemical evidence in the geologic record.
The Chicxulub impact had catastrophic consequences for life on Earth, triggering one of the most significant mass extinctions in Earth's history. Geological, paleontological, and geochemical evidence, supported by modern climate and environmental models, provides a detailed understanding of how this event unfolded and its far-reaching effects on the planet's history.
Tracking down the asteroid that sealed the fate of the dinosaursThis conclusion comes from comparing the composition of the global layer resulting from this impact and from the impact site itself (rich in the platinum-group elements, iridium, ruthenium, osmium, rhodium, platinum, and palladium, which are otherwise rare in Earth's crust) and comparing them with the composition of multiple classes of meteorite. They found that the Chicxulub impact meteor was carbonaceous asteroid that formed in the outer Solar System. Additional measurements of five other impacts showed that those were due to silicate asteroids that formed in the inner Solar System.
The asteroid that led to the extinction of the dinosaurs 66 million years ago probably came from the outer solar system / publication in ‘Science’
Geoscientists from the University of Cologne have led an international study to determine the origin of the huge piece of rock that hit the Earth around 66 million years ago and permanently changed the climate. The scientists analysed samples of the rock layer that marks the boundary between the Cretaceous and Paleogene periods. This period also saw the last major mass extinction event on Earth, in which around 70 percent of all animal species became extinct. The results of the study published in Science indicate that the asteroid formed outside Jupiter’s orbit during the early development of our solar system.
According to a widely accepted theory, the mass extinction at the Cretaceous-Paleogene boundary was triggered by the impact of an asteroid at least 10 kilometres in diameter near Chicxulub on the Yucatán Peninsula in Mexico. On impact, the asteroid and large quantities of earth rock vaporized. Fine dust particles spread into the stratosphere and obscured the sun. This led to dramatic changes in the living conditions on the planet and brought photosynthetic activity to a halt for several years.
The dust particles released by the impact formed a layer of sediment around the entire globe. This is why the Cretaceous-Paleogene boundary can be identified and sampled in many places on Earth. It contains high concentrations of platinum-group metals, which come from the asteroid and are otherwise extremely rare in the rock that forms the Earth’s crust.
By analysing the isotopic composition of the platinum metal ruthenium in the cleanroom laboratory of the University of Cologne’s Institute of Geology and Mineralogy, the scientists discovered that the asteroid originally came from the outer solar system.
The asteroid’s composition is consistent with that of carbonaceous asteroids that formed outside of Jupiter’s orbit during the formation of the solar system.
Dr Mario Fischer-Gödde, first author
Institut für Geologie und Mineralogie
University of Cologne, Cologne, Germany.
The ruthenium isotope compositions were also determined for other craters and impact structures of different ages on Earth for comparison. This data shows that within the last 500 million years, almost exclusively fragments of S-type asteroids have hit the Earth. In contrast to the impact at the Cretaceous-Paleogene boundary, these asteroids originate from the inner solar system. Well over 80 percent of all asteroid fragments that hit the Earth in the form of meteorites come from the inner solar system.
We found that the impact of an asteroid like the one at Chicxulub is a very rare and unique event in geological time. The fate of the dinosaurs and many other species was sealed by this projectile from the outer reaches of the solar system.
Professor Dr Carsten Münker, co-author
Institut für Geologie und Mineralogie
University of Cologne, Cologne, Germany.
What will upset creationists is not only that this occurred so long before their legendary 'Creation Week', but also the fact that this impact left a global layer as a record, whereas their favourite global catastrophe, the legendary genocidal flood just a few thousand years ago, left no such trace. Not even a fossil from the wrong landmass of even a collection of sediment in an alpine valley consistent with being deposited there during a period of submergence beneath thousands of feet of water, containing the bodies of millions of drowned animals and plant debris.
Sadly, the body of the paper is embargoes for 12 months from the date of publication, in accordance with the Journal's default licence, so only the abstract is available.
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.
Mario Fischer-Gödde et al. ,
Ruthenium isotopes show the Chicxulub impactor was a carbonaceous-type asteroid. Science 385, 752-756(2024). DOI:10.1126/science.adk4868
© 2024 American Association for the Advancement of Science.
Reprinted with kind permission under licence #5852140462131.
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