Was the Chicxulub bolide 65 million years ago an asteroid from beyond Jupiter?

According to a new study, the Chicxulub bolide that impacted the Yucatan 65 million years ago and is thought to have been a major cause of the extinction of the dinosaurs was likely a carbonaceous-type asteroid from beyond Jupiter.

The researchers attempted to pinpoint the nature of that bolide by analyzing the isotope samples from the thin layer of materials found worldwide that corresponds to the impact (dubbed the K-Pg boundary) as well number of different impact samples from different layers.

To address these questions, Mario Fischer-Gödde and colleagues evaluated ruthenium (Ru) isotopes in samples taken from the K-Pg boundary. For comparison, they also analyzed samples from five other asteroid impacts from the last 541 million years, samples from ancient Archaean-age (3.5 – 3.2 billion-years-old) impact-related spherule layers, and samples from two carbonaceous meteorites.

Ficher-Gödde et al. found that the Ru isotope signatures in samples from the K-Pg boundary were uniform and closely matched those of carbonaceous chondrites (CCs), not Earth or other meteorite types, suggesting that the Chicxulub impactor likely came from a C-type asteroid that formed in the outer Solar System. They also rule out a comet as the impactor. Ancient Archean samples also suggest impactors with a CC-like composition, indicating a similar outer Solar System origin and perhaps representing material that impacted during Earth’s final stages of accretion. In contrast, other impact sites from different periods showed Ru isotope compositions consistent with S-type (salicaceous) asteroids from the inner Solar System.

My headline poses this result as a question because these results are unconfirmed, and based on a very small sample of data. Nonetheless, this research not only gives us a better idea of the nature of the Chicxulub impactor, it does the same for a number of other important past impacts. That data in turn will help theorists refine their theories describing the early formation history of the solar system.

Sidebar: As always, there are numerous stories today in the mainstream press going ga-ga over this paper and declaring with certainty the utter truth of its conclusions. This of course is junk reporting, as there is no utter truth here, only some educated speculation based on some new data.

The on-going vicious debate over dinosaur extinction

Link here. The article is a very well-written and detailed description of the large doubts held by many paleontologists about the theory that a single asteroid/comet impact in Mexico caused the entire dinosaur extinction 65 million years ago. Key quote:

Ad hominem attacks had by then long characterized the mass-extinction controversy, which came to be known as the “dinosaur wars.” Alvarez [the man who first proposed the impact theory] had set the tone. His numerous scientific exploits—winning the Nobel Prize in Physics, flying alongside the crew that bombed Hiroshima, “X-raying” Egypt’s pyramids in search of secret chambers—had earned him renown far beyond academia, and he had wielded his star power to mock, malign, and discredit opponents who dared to contradict him. In The New York Times, Alvarez branded one skeptic “not a very good scientist,” chided dissenters for “publishing scientific nonsense,” suggested ignoring another scientist’s work because of his “general incompetence,” and wrote off the entire discipline of paleontology when specialists protested that the fossil record contradicted his theory. “I don’t like to say bad things about paleontologists, but they’re really not very good scientists,” Alvarez told The Times. “They’re more like stamp collectors.”

Scientists who dissented from the asteroid hypothesis feared for their careers. Dewey McLean, a geologist at Virginia Tech credited with first proposing the theory of Deccan volcanism, accused Alvarez of trying to block his promotion to full professor by bad-mouthing him to university officials. Alvarez denied doing so—while effectively bad-mouthing McLean to university officials. “If the president of the college had asked me what I thought about Dewey McLean, I’d say he’s a weak sister,” Alvarez told The Times. “I thought he’d been knocked out of the ball game and had just disappeared, because nobody invites him to conferences anymore.” Chuck Officer, another volcanism proponent, whom Alvarez dismissed as a laughingstock, charged that Science, a top academic journal, had become biased. The journal reportedly published 45 pieces favorable to the impact theory during a 12-year period—but only four on other hypotheses. (The editor denied any favoritism.)

In 1999, almost twenty years ago, I wrote a long article for a magazine called The Sciences describing this very same debate, including the efforts at the journal Science to push the impact theory and damage the careers of any dissenters. At the time I found the doubts by paleontologists to be widespread, backed up by lots of very credible evidence, including the fundamental data from the fossil record, which simply did not show an instantaneous extinction.

I also discovered that the planetary science community and many in the press were responding not with good science but with ad hominem attacks aimed at destroying anyone who disagreed with the impact theory. I also discovered that the editor at The Sciences who was assigned to edit my piece did not want me to reveal these facts. He was very liberal, had bought into the impact theory, as well as global warming, and like so many liberals I have met in my life he preferred squelching facts rather than allowing the facts to speak. In this case, he was not the editor in charge, and was unable to prevent my article’s publication, as I wanted it written.

Now twenty years later, the same debate continues, though under the radar because of the successful public relations effort by those on the impact theory side to bury the debate. If you were to ask almost any ordinary citizen what caused the extinction of the dinosaurs, they would immediately say a asteroid/comet impact, and would assume that all scientists agree. Sadly, that is not the case, and has never been the case.

Read the article. It details this story quite nicely, and reveals once again the corruption that began permeating the science community in the 1980s and now warps so much research.

Drilling at the Chicxulub impact site has unveiled the crater’s shape

The new rock core drilled at the crater impact site that is thought to have help cause the extinction of the dinosaurs 65 million years ago has helped reveal the crater’s formation and shape, including the existence of an inner ring of mountains which scientists call a peak-ring.

After a decade of planning, the project penetrated 1,335 metres into the sea floor off the coast of Progreso, Mexico, in April and May. Drillers hit the first peak-ring rocks at a depth of 618 metres, and a pinkish granite at 748 metres. Geologists know that the granite must have come from relatively deep in the crust — perhaps 8–10 kilometres down — because it contains big crystals. The size of these crystals suggests that they formed by the slow cooling of deep, molten rock; in contrast, rapid cooling at shallow depth tends to form small crystals. Finding the granite relatively high in the drill core means that something must have lifted it up and then thrown down it on top of other rocks.

That rules out one idea of how craters form, in which the pulverized rock stays mostly in place like hot soup in a bowl. Instead, the core confirms the ‘dynamic collapse’ model of cosmic impacts, in which the asteroid punches a deep hole in the crust, causing the rock to flow like a liquid and spurt skyward. That rock then falls back to Earth, splattering around in a peak ring.

To put it another way, the impact moved the earth like a pebble dropped into a pond of water, causing at least two big circular ripples that flowed just like water but then quickly froze in place to form the two concentric peak-ring mountain ranges.