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Massive Volcanic Eruptions Accompanied Dinosaur Extinction

Posted by Soulskill on from the some-say-dinosaurs-can't-swim-in-magma dept.

schwit1 writes: A careful updating of the geological timeline has shown that massive volcanic eruptions aligned with the extinction event that wiped out the non-avian dinosaurs 66 million years ago (abstract). "A primeval volcanic range in western India known as the Deccan Traps, which were once three times larger than France, began its main phase of eruptions roughly 250,000 years before the Cretaceous-Paleogene, or K-Pg, extinction event, the researchers report in the journal Science. For the next 750,000 years, the volcanoes unleashed more than 1.1 million cubic kilometers (264,000 cubic miles) of lava. The main phase of eruptions comprised about 80-90 percent of the total volume of the Deccan Traps' lava flow and followed a substantially weaker first phase that began about 1 million years earlier.

The results support the idea that the Deccan Traps played a role in the K-Pg extinction, and challenge the dominant theory that a meteorite impact near present-day Chicxulub, Mexico, was the sole cause of the extinction. The researchers suggest that the Deccan Traps eruptions and the Chicxulub impact need to be considered together when studying and modeling the K-Pg extinction event."

14 of 78 comments (clear)

  1. Antipodal eruptions by mbone · · Score: 5, Interesting

    This may revive the theory that the Deccan traps were formed at the antipode of a major eruption - the seismic waves will focus there, and could crack the Earth's crust (for a really big impact).

    It seems logical, and the positions more or less fit, but the question was always whether the timing was viable.

    Now, where is the crater that formed the Siberian traps. And, did it end the Permian period?

    1. Re:Antipodal eruptions by killkillkill · · Score: 2

      Oh, maybe they found it already.

    2. Re:Antipodal eruptions by DerekLyons · · Score: 2

      Except, the theory is trivially disproved - during the Cretaceous period, the Chicxulub crater and the Deccan traps weren't at each others antipodes.

    3. Re:Antipodal eruptions by Convector · · Score: 2

      I've never found the antipodal argument convincing. Seismic waves converge at the antipode of an impact only if the target is spherically symmetric and isotropic. In the actual Earth, you have reflections off all kinds of laterally varying boundaries. Also, the sound speed differs substantially between continental and oceanic crust, so the path matters quite a bit.

      The Chixulub impact is also not that big (as planetary-scale impacts go). The projectile was what, 10 km? Shock heating is only significant within a few times the projectile diameter.

    4. Re:Antipodal eruptions by cellocgw · · Score: 2

      I'd be more inclined to believe we don't have our dating methods perfected quite yet.

      Wait: you talking about archaeologists or slashdot members here?

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    5. Re:Antipodal eruptions by Jeeeb · · Score: 2

      From the link:

      The crater is about 300 miles wide. It was found by looking at differences in density that show up in gravity measurements taken with NASA's GRACE satellites. Researchers spotted a mass concentration, which they call a mascon-dense stuff that welled up from the mantle, likely in an impact.

      So Frese and colleagues overlaid data from airborne radar images that showed a 300-mile wide sub-surface, circular ridge. The mascon fit neatly inside the circle.

      Far from definite but the evidence is far stronger than you are making out.

    6. Re:Antipodal eruptions by schnell · · Score: 4, Funny

      I'd be more inclined to believe we don't have our dating methods perfected quite yet.

      Wait: you talking about archaeologists or slashdot members here?

      Either you are a creationist who believes humans and non-Avian dinosaurs coexisted or don't know the difference between an archaeologist and a paleontologist.

      No, see, he was making a joke. "Dating" is a homonym, it can mean the act of establishing how old a thing is or it can mean the act of romantic courtship. And he's making a joke about how people on Slashdot might not be good at interacting with (typical) females since they tend to be so literal and have a hard time doing things like interpreting social meaning or context or...

      You know what? Fuck it, you're right. He's a creationist.

      --
      "95% of all Slashdot .sig quotes are incorrect or completely fabricated." -Benjamin Franklin
  2. Re:So it wasn't global warming? by ihtoit · · Score: 2

    no, it was Baldrick's underpants.

    --
    Political debates have me rolling my eyes so much I think I got optical whiplash. I should sue. - Foamy The Squirrel
  3. Things happen - multiple things by Livius · · Score: 4, Informative

    I'm not convinced many actual scientists believe that the Chicxulub asteroid impact "was the sole cause of the extinction" - the best version I've heard is that the Deccan Traps eruptions had already put the ecosystem under stress.

    The degree to which each event contributed to the mass extinction remains a fascinating question.

    1. Re:Things happen - multiple things by hey! · · Score: 2

      Back in the early 90s I had the opportunity of participating on a paleontological expedition to the badlands of Montana. The soil was built up over hundreds of millions of years and flooding cut through the soft soil leaving a stratigraphy that is dramatic and easy to read. You can even see the Chicxulub ejecta, a chocolate brown horizontal line about the width of your hand.

      Now whole dinosaur skeletons are a rare find. You can spend a whole season tramping through the badlands and never find two bones that go together. But individual bones are more common, and bone fragments are more common still, and experts can often identify the group of dinosaurs or even the species of dinosaur a bone fragment came from, often a surprisingly small fragment of bone.

      What we were doing was assembling a database of species found by layer, which in turn maps to era. What the PI was finding was a shift towards species with anatomical adaptations to deal with heat. His opinion was that there was already a climate driven adaptive stress on the dinosaur population, which turned the aftermath of the Chicxulub impact into a knock-out blow.

      So the idea that there was more going on than an asteroid impact is hardly new. People were thinking that way twenty years ago.

      --
      Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
  4. Probably a mix by Doghouse13 · · Score: 3, Interesting

    Not the first time I've heard this suggested. But then, given how long the dinosaurs survived, it seems intuitively that it must have taken something highly improbable - a "perfect storm" of disasters - to disrupt ecosystems enough to shift them worldwide.

  5. Re:scentists by epyT-R · · Score: 2

    well scientists care about these things because the more knowledge we have of the past the better we can predict the future. scentists on the other hand, only care about the stench of your butt.

  6. Statistically not drastic by Celarent+Darii · · Score: 3, Interesting

    The summary states that over 750,000 years the volcanoes emitted 1.1 E 6 km^2. Over that timespan it doesn't seem like much, a bit more than 1 km^2 a year. This does not seem that significant.

    For instance, the Bardarbung volcano in Iceland, which erupted this year, has already produced 1 km^2 of lava, and has no sign of stopping. At that rate, for 750,000 years it would be close to the magnitude of the volcanoes in the summary. And yet the impact of Bardarbung on earthly climate is close to negligible - we are not yet extinct in any case. For an extinction event one would expect something a bit more drastic, it would seem to me.

    Some info on Bardarbung here

  7. Re:So - an impact of an asteroid.... by turkeyfish · · Score: 2

    The only problem with that is that some volcanic activity predated the bolide impact.