35 Million-Year-Old Asteroid Left a Trail of Destruction Across the Eastern US (space.com) 36
schwit1 shares a report from Space.com: About 35 million years ago, an asteroid traveling nearly 144,000 mph (231,000 km/h) smashed into the Atlantic Ocean near the modern-day town of Cape Charles, Virginia. The space rock vaporized instantly, but its impact triggered a gargantuan tsunami, cast up a monsoon of shattered rocks and molten glass that spanned hundreds of miles and carved out the single largest crater in the United States -- the so-called Chesapeake Bay impact structure. Today, that 25-mile-wide (40 kilometers) crater is buried half a mile below the rocky basement of Chesapeake Bay -- the 200-mile-long (320 km) estuary linking Virginia and Maryland on the East Coast. That hasn't stopped scientists from trying to piece together the site's mysterious history since it was first discovered during a drilling project in 1990.
In a recent study of ocean sediment cores taken almost 250 miles (400 km) northeast of the impact site, researchers found traces of radioactive debris dating to the time of the strike, providing fresh evidence of the impact's age and destructive power. In their recent study (published in the journal Meteoritics and Planetary Science), researchers from Arizona State University dated 21 microscopic shards of zircon -- a durable gemstone that can survive underground for billions of years. These zircons were lodged in a sediment core taken from roughly 2,150 feet (655 meters) below the Atlantic Ocean. Not only is zircon commonly found in tektites, but it is also a choice mineral for radiometric dating, thanks to some of its radioactive elemental components. In this case, the researchers used a dating technique called uranium-thorium-helium dating, which looks at how radioactive isotopes, or versions, of uranium and thorium decay into helium. The team found that the 21 crystals ranged widely in age, running the gamut from about 33 million to 300 million years old. The two youngest samples, which had an average age of about 35 million years old, fit in with previous studies' estimates for the time of the Chesapeake Bay impact.
In a recent study of ocean sediment cores taken almost 250 miles (400 km) northeast of the impact site, researchers found traces of radioactive debris dating to the time of the strike, providing fresh evidence of the impact's age and destructive power. In their recent study (published in the journal Meteoritics and Planetary Science), researchers from Arizona State University dated 21 microscopic shards of zircon -- a durable gemstone that can survive underground for billions of years. These zircons were lodged in a sediment core taken from roughly 2,150 feet (655 meters) below the Atlantic Ocean. Not only is zircon commonly found in tektites, but it is also a choice mineral for radiometric dating, thanks to some of its radioactive elemental components. In this case, the researchers used a dating technique called uranium-thorium-helium dating, which looks at how radioactive isotopes, or versions, of uranium and thorium decay into helium. The team found that the 21 crystals ranged widely in age, running the gamut from about 33 million to 300 million years old. The two youngest samples, which had an average age of about 35 million years old, fit in with previous studies' estimates for the time of the Chesapeake Bay impact.
Sweet Meteor Of Death (Score:1, Funny)
Can we get another one in time for the 2020 election?
Re: Sweet Meteor Of Death (Score:2)
We can live beside the ocean
Leave the fire behind
Swim out past the breakers
Watch the world die
Can't read the article (Score:4, Informative)
Re:Can't read the article (Score:4, Funny)
Space.com pops up a page that ironically says that "while we don't mind you running an ad blocker", then proceeds to claim otherwise by completely obscuring the article page.
I just had to click "continue with adblocker". But then I saw a mindbogglingly stupid stock image of some idiot graphic artist's impression of what a meteorite impact looks like. I wish it had stayed obscured.
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Besides an adblocker I really recommend an auto overlay remover. It stops those annoying boxes that want your email address every time you visit a site. You have to whitelist some sites but totally worth the trouble.
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I didn't know such a thing existed, but I tried this one and found it worked with the site linked in TFA: https://chrome.google.com/webstore/detail/auto-overlay-remover/kefcbonbdcahbihclibfdeeddceiabjm [google.com]
Works like a champ in Brave, too.
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Me too, so they got the usual treatment. Click uBlock Origin icon, click the </> icon on its menu to disable scripting, then reload page. Then also delete all space.com cookies and deny permission to ever store a cookie for them again.
You fuck with my adblocker, you get even more blocked than my usual rather gracious and bend-over-backwards-permissive defaults. That's just how it has to be. You'd have to be crazy to be more permissive than I am, and most people would think I already allow far too muc
Re: Can't read the article (Score:2)
They're like a passive-aggresive parent. "You're free to wear whatever you want to school. But do you really need to wear THAT?"
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Or it means you're running an ad-blocker. I dunno.
NYT headline, "Trump fails to stop asteroid!" (Score:2, Funny)
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First, what the fuck does any of this have to do with the Orange Man? Some people's (you) obsession with this guy goes even beyond the extreme right's obsession with Obama. It's unhealthy, and you should seek help - not only for your own well being, but for those around you. Maybe this is another symptom of dismantling mental health services in the US?
Second, it was Arizona State University doing the research that this article is about, not the University of Arizona. I know they both have the word "Ariz
Re: NYT headline, "Trump fails to stop asteroid!" (Score:1)
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Re: NYT headline, "Trump fails to stop asteroid!" (Score:2)
He could accuse the liberal media of spreading fake news and make us all feel better about our imminent destruction.
As Commander in Chief it is his responsibility to placate the irrational masses with populism and jingoism.
Make China pay for the asteroid deflector. Their HUGE population obviously drew it here.
Amateurish question (Score:2)
So TFA says they found 21 shards of zircon, out of which 2 were of similar age. So, by my understanding, they used 10% of the samples (only the convenient ones) to confirm their theory? Isn't this confirmation bias?
Re:Amateurish question (Score:5, Informative)
You're asking if the noise inherent in the measurement is approximately the same as the noise across the samples in this case. Or, to put it another way, you are wondering if the two non-matching samples should be considered outliers and ignored.
I have a good friend (no, really) who builds the machines that do exactly this sort of radiological dating. The size of a dinner table, they cost upwards of USD 100,000 installed and are precision scientific instruments. They take single grains of zircon (or other material), laser ablate them under high vacuum, and give you the elemental composition via mass spectrometry. Used properly, the noise in their results is far, far lower than across these samples.
The reason zircon is used is because it tends to trap He4 nuclei that are given off during radioisotope decay, such as U/Th under certain circumstances, such as -- and this is the key point -- when the zircon is below about 90C. It's widely assumed that the thermal shock from a meteor impact will heat zircons well above that thermal barrier, allowing all entrapped He4 to escape, resetting the U/Th decay clock. After the thermal shock, U/Th decay chain continues, slowly releasing more He4 which is trapped after the grains cool down, allowing the slow buildup to provide an indicator of the time since cooling. Measurements of this and similar phenomena have created the field of geothermochronology, yielding a vast trove of interesting results. It's given my friend a pretty comfortable living, too, building and installing these machines in universities across the globe.
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Thank you, that was a very informative post.
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I took that to mean that some of the samples were from earlier impacts or other sources. The presence of two samples from about 35 million years ago supports the theory of an impact at that time. The presence of samples from other impacts does not detract from that.
As a life-long resident of the Chesapeake... (Score:2)
oh, this is a good one, and S.C. Lizardmen, too! (Score:2)
n.b. do your own damn internet "research". Do the Woo. Parts of this post may contain wild conjecture, worse, parts of it don't.
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Are you referring to those small Fireball botles you find littered all over the east coast?
Wouldn't there be biological markers of this event (Score:2)
I would think that an event like this would alter the biosphere of Earth as well as the local flora/fauna of the impact site.
TFA only talks about the geological impact but I would think there would be some pretty spectacular impact on the plants and animals (as well as the climate) that should be investigates as well.
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Thanx for the reference.
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A different dating system (Score:1)
It's called uranium-thorium-helium dating, but you need to get out of the basement to be eligible.
I'll get crucified again but here we go (Score:2)
Here's the dickhead again, complaining:
Article about an Encarta CD from 25 years ago.
Article about mining crypto on 40 year old Apple II.
Article about an asteroid from 35 million years ago.
Tomorrow news from the big bang.
Stuff that matters.
Re: I'll get crucified again but here we go (Score:2)
The big bang is news to me.
How do they know... (Score:3)
...how old the asteroid was when it "died"? Or was the headline writer just brain dead when writing it?
Re: How do they know... (Score:2)
It's a bit weird. If they used the word meteorite then we at least can pedantically justify. But asteroids float around can originate from the early solar solar system (5 Bya?)