New research on impact crater blows up previous estimates of its age | Science


If you travel 140 miles southeast of Kiev, Ukraine, just before reaching the small village of Bukvarka, you will come to a patch of forest that crisscrosses farmland. The gently sloping meadows and cottages are bucolic, leaving no trace of the region’s violent past. But dig about 1,700 feet and you’ll find the remnants of a catastrophic impact: an asteroid crater 15 miles wide.

Scientists say that around 65 million years ago, an asteroid the length of three Eiffel towers struck here, its flaming fallout covering an area the size of present-day Vermont. The impact dumped a colossal amount of heat into the ground, enough to melt the rock and form a massive depression called the Boltysh Crater, a hole now filled with detritus from asteroids and sediment from a long-gone lake. .

Previous studies have given Boltysh’s impact a wide range of dates to suggest that it may have coincided with Chicxulub’s impact, with the two asteroids both contributing to the extinction of the dinosaurs. Now, a more precise follow-up study published today in Scientists progress suggests that the Boltysh impact occurred 650,000 years later than the Chicxulub impact, long after the dinosaurs were extinct. Although Boltysh’s impact is no longer identified in the famous mass extinction event, identifying the age of the crater has allowed scientists to correlate the asteroid strike with other global upheavals of its time. .

“You are trying to document a major event which, fundamentally, surely shaped the biosphere and changed the evolution of the Earth,” explains Philippe Claeys, a geologist at the Free University of Brussels, Belgium, who was not involved in study. “You will have to understand every event that is taking place at that time. Is it important to document an event like Boltysh? Absolutely.”

Annemarie Pickersgill, a geologist at the University of Glasgow, UK, who led the research, dated Boltysh Crater by examining the age of the sediment that had settled there. These sediments came from rocks that were melted by the impact of asteroids and soil that accumulated over the millions of years that followed. His team examined core drilled from this sediment pile using a dating method that measures the build-up of a particular isotope of argon and estimated the age of the crater at 65.39 million. years.

“It’s a very nice study,” says Claeys. “The Argon Ages are absolutely magnificent.”

The first attempts to date Boltysh Crater in the early 2000s involved the same dating method, but with less accuracy due to technological limitations. Scientists estimated that the impact occurred over a period of 1.3 million years. The imprecise measurement left open the possibility that Boltysh’s impact may have overlapped with Chicxulub’s fateful formation. This wide age group has fueled speculation that Impactor Boltysh, beating Chicxulub on Earth by a hair’s breadth of a hair, acted as the first of a punch that wiped out the dinosaurs. In the 18 years since the first study, dating techniques have improved to the point that Pickersgill’s team has been able to quadruple the accuracy of the measurement, disentangling Boltysh and Chicxulub once and for all. Their results confirm that the Boltysh has nothing to do with the extinction of the dinosaurs, as it happened much later. “If there’s a break-in and I get to the bank later, nobody’s going to say, ‘You were there, you did it,’” says Pickersgill.

Boltysh’s impact may no longer be culpable for contributing to the extinction of the dinosaurs, but his more precise new age places him in a time of great climatic upheaval. The Boltysh impactor made landfall just at the end of the Deccan Trap volcanic period, when the earth’s volcanic veins separated and spewed large amounts of greenhouse gases into the atmosphere. At this time of widespread volcanic activity, while the planet was still reeling from the impact event that formed the Chicxulub crater, a new hyperthermic event began, a period of extreme global warming during which ocean temperatures have risen by nearly four degrees Fahrenheit. New findings from Pickersgill’s team make Boltysh impact a suspect for triggering the hydrothermal event.

Normally, an asteroid the size of Boltysh’s impactor – ten times smaller than the famous rock that formed Chicxulub – would be too puny to cause damage on a global scale. Nonetheless, the impactor may have triggered a series of unfortunate events as the planet was already in a fragile state.

“One question we asked was, when [Earth] was already pointed out, was it possible that a small impact could have pushed things overboard for hyperthermia? Said Pickersgill.

The jury is still out, she said. The age of Boltysh Crater alone is not sufficient evidence to prove the asteroid’s guilt, and she cannot speculate on how an impact could have triggered subsequent events. More follow-up studies are needed, she says.

Sonia Tikoo, a geophysicist at Stanford University who was not involved in the research, says she believes the Boltysh impactor was too small to have triggered global climate change. Although the age of the crater is strangely close to the hyperthermic event, “it’s just a beautiful coincidence… but I’m not sure they’re related,” she said. Still, the new study encourages scientists to think about how the size of asteroids and the target rocks they crash into disrupt the climate. “It makes us want to dig a little deeper into these questions,” she says.

The Earth is constantly dotted with celestial bodies, including larger visitors like the Boltysh and Chicxulub impactors which strike every one to three million years. On geological timescales, asteroid events aren’t that frightening, and their craters are important records of Earth’s past. Boltysh may no longer have played a role in the extinction of the dinosaurs, but “it’s another part of the whole story” of a very eventful time, Claeys says.

Editor’s Note, June 18, 2021: This article initially misspelled the hyperthermic event. We regret the error.


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