• Artist's rendering of the landscape during end-Permian extinction.

    Image: José-Luis Olivares/MIT

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  • A photo of the permian triassic boundary at Meishan, China. This photo shows the limestone beds in between the volcanic ash beds that the researchers were able to date.

    Photo: Shuzhong Shen

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An extinction in the blink of an eye

MIT researchers find that the end-Permian extinction happened in 60,000 years — much faster than earlier estimates.


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The largest mass extinction in the history of animal life occurred some 252 million years ago, wiping out more than 96 percent of marine species and 70 percent of life on land — including the largest insects known to have inhabited the Earth. Multiple theories have aimed to explain the cause of what’s now known as the end-Permian extinction, including an asteroid impact, massive volcanic eruptions, or a cataclysmic cascade of environmental events. But pinpointing the cause of the extinction requires better measurements of how long the extinction period lasted.

Now researchers at MIT have determined that the end-Permian extinction occurred over 60,000 years, give or take 48,000 years — practically instantaneous, from a geologic perspective. The new timescale is based on more precise dating techniques, and indicates that the most severe extinction in history may have happened more than 10 times faster than scientists had previously thought.

“We’ve got the extinction nailed in absolute time and duration,” says Sam Bowring, the Robert R. Shrock Professor of Earth and Planetary Sciences at MIT. “How do you kill 96 percent of everything that lived in the oceans in tens of thousands of years? It could be that an exceptional extinction requires an exceptional explanation.”

In addition to establishing the extinction’s duration, Bowring, graduate student Seth Burgess, and a colleague from the Nanjing Institute of Geology and Paleontology also found that, 10,000 years before the die-off, , the oceans experienced a pulse of light carbon, which likely reflects a massive addition of carbon dioxide to the atmosphere. This dramatic change may have led to widespread ocean acidification and increased sea temperatures by 10 degrees Celsius or more, killing the majority of sea life.

But what originally triggered the spike in carbon dioxide? The leading theory among geologists and paleontologists has to do with widespread, long-lasting volcanic eruptions from the Siberian Traps, a region of Russia whose steplike hills are a result of repeated eruptions of magma. To determine whether eruptions from the Siberian Traps triggered a massive increase in oceanic carbon dioxide, Burgess and Bowring are using similar dating techniques to establish a timescale for the Permian period’s volcanic eruptions that are estimated to have covered over five million cubic kilometers.

“It is clear that whatever triggered extinction must have acted very quickly,” says Burgess, the lead author of a paper that reports the results in this week’s Proceedings of the National Academy of Sciences, “fast enough to destabilize the biosphere before the majority of plant and animal life had time to adapt in an effort to survive.”

Pinning dates on an extinction

In 2006, Bowring and his students made a trip to Meishan, China, a region whose rock formations bear evidence of the end-Permian extinction; geochronologists and paleontologists have flocked to the area to look for clues in its layers of sedimentary rock. In particular, scientists have focused on a section of rock that is thought to delineate the end of the Permian, and the beginning of the Triassic, based on evidence such as the number of fossils found in surrounding rock layers.

Bowring sampled rocks from this area, as well as from nearby alternating layers of volcanic ash beds and fossil-bearing rocks. After analyzing the rocks in the lab, his team reported in 2011 that the end-Permian likely lasted less than 200,000 years. However, this timeframe still wasn’t precise enough to draw any conclusions about what caused the extinction.

Now, the team has revised its estimates using more accurate dating techniques based on a better understanding of uncertainties in timescale measurements.

With this knowledge, Bowring and his colleagues reanalyzed rock samples collected from five volcanic ash beds at the Permian-Triassic boundary. The researchers pulverized rocks and separated out tiny zircon crystals containing a mix of uranium and lead. They then isolated uranium from lead, and measured the ratios of both isotopes to determine the age of each rock sample.

From their measurements, the researchers determined a much more precise “age model” for the end-Permian extinction, which now appears to have lasted about 60,000 years — with an uncertainty of 48,000 years — and was immediately preceded by a sharp increase in carbon dioxide in the oceans.

‘Spiraling toward the truth’

The new timeline adds weight to the theory that the extinction was triggered by massive volcanic eruptions from the Siberian Traps that released volatile chemicals, including carbon dioxide, into the atmosphere and oceans. With such a short extinction timeline, Bowring says it is possible that a single, catastrophic pulse of magmatic activity triggered an almost instantaneous collapse of all global ecosystems.

Andrew Knoll, a professor of earth and planetary sciences at Harvard University, says the group’s refined timeline will give scientists an opportunity to test whether the timing of the Siberian Traps eruptions coincides with the extinction.

“Most mechanisms proposed to account for the observed pattern of extinction rely on rapid environmental change, so the sharp constraints on timing also serve as tests of these ideas,” Knoll says.  “[This new timeline] bring us closer to the resolution of a major problem posed by the geologic record.”

To confirm whether the Siberian Traps are indeed the extinction’s smoking gun, Burgess and Bowring plan to determine an equally precise timeline for the Siberian Traps eruptions, and will compare it to the new extinction timeline to see where the two events overlap. The researchers will investigate additional areas in China to see if the duration of the extinction can be even more precisely determined.

“We’ve refined our approach, and now we have higher accuracy and precision,” Bowring says. “You can think of it as slowly spiraling in toward the truth.”


Topics: Geology, Mass extinction, Geochronology

Comments

Simply, if I say I see six, give or take four, would you trust my observation? To say 60k years with a 96k variance is to, well, just sound stupid! How can a variance be 80% of the figure? How is that even possible or "scientific"? To a layman it is silly. Just saying...
Can you direct me to any publications for reference purposes? has this hit any journal. Thanks
@wayner1 - When you narrow something down to a span of 60k years for something that happened 252 million years ago, the +/- 48k years is miniscule.
Wayner1, would it be more palatable to you to say that the event took somewhere between 12,000 and 108,000 years, as opposed to the vast range of possibilities that were considered before this finding? This team has narrowed what used to be a much more uncertain and much larger range to a relatively tiny one, in geologic terms. To answer your question in the terms in which you asked it: If it were thought that a given event might have taken as much as, say, 100 years, and you told me that in fact it took between 2 and 10 years, then yes, I would think you had made a significant finding.
What will we do with them?
Eventually, evidence will validate the impact of an asteroid (not a comet) prior to the eruptions and basaltic lava flows associated with the Siberian Traps near the antipodal location at that point in time. Since that impact location in today's Southern Ocean is at great depth, discovery will require detailed assessment of deeper subsurface geology by remote means rather than directly drilling to retrieve a physical core of the strata, at least until deepwater drilling technology has advanced a lot farther. The logical sequence is: 1) external body impact (high-angle trajectory) which penetrates and shatters the mantle around the impact site, triggering 2) massive seismic waves that travel around the planet's mantle shell and pulses into the molten interior which 3) repeatedly converge in both the Siberian Traps and impact regions, rupturing the crust to great depth and producing massive outgassing over a long period of time, forcing abrupt climate change and oceanic acidification.
I saw a BBC documentary recently on the Permian Extinction, & it indicated that many researchers feel the Siberian Traps are probably the cause, but at that time, around 2011, the extinction was thought to have taken around 80,000-200,000 years, slower than the newer estimates. One scientist, Mike Rampino, theorized that for an extinction to happen very rapidly, not even the Siberian Traps could have caused it, & that it may have been a giant impact, even larger than the KT impact 66mya. Of course, there is no known crater, & not much of a global iridium layer or spherules, not to mention impact debris. The Permian impact, if it occured, even if it did as some think, been so ferocious as to cause lava to seep up & quickly bury the crater, should have left global signatures, if it were around 15km, in the form of massive impact dust, evidence of tsunamis, etc. But there seems to be little to none of this. So maybe it was Siberian Traps? How about a gamma ray burst, or supernova?
Well ; The MIT Geophysicists theory simply lacks the fundamental understanding in `evolutionary `direction as well as `thermodynamics of our universe` ; in other words the evolutionary leading(guiding) incentive/motive has always been source of `Energy` -food that is- and without energy source(food) there will be no evolution towards diversification of living things over time but a `bottle neck` , this fundamental principle of evolution applies `Archaea` too of course , acidification of the oceans is the first requirement so the `energy/food` source of `Archaea ` will be abundant , acidification is the `leading(guiding) event of extinction NOT other way around , simply you can not create food(energy) to sustain life –from nothing- it has to be `external source` because you can not self sustain or self create energy from nothing . The external source which has to be the `sun`s radiation energy ` or celestial events related chemical reactions , like volcanic activity etc . ; fundamentally biologic systems(living matter) has always been AGAINST the fundamental `entropy principle` of nonliving matter of our universe ; in which(living matter) the entropy always `decreases` towards to `Maximum Orderliness with Maximum energy` that the very energy needed for orderliness comes from non living matter –sun`s radiation , volcanic activity related chemical processes , heat , inorganic chemical processes etc . In other words without energy living matter can NOT create its own self sustaining energy , energy always comes from the nonliving things in our universe , the fundamental flow direction of energy is from nonliving matter towards living matter as always with not even a single exception to this rule exist in our Earth with life forms . As you may know the fundamental principle of Entropy in our Universe is Minimum energy with Maximum Randomness since the Big Bang 13,8 billion years ago .. So MIT Geophysicists obviously need to comprehend fully `what living things are all about in this universe` in other words `biology` ` fundamentals of evolution` and `the second law of thermodynamics particularly` ; before making any claim on their theory . So the Permian mass extinction 252 million years ago simply CAN NOT be created (initiated) by `Archaea` life forms or self sustain once started by Archaea life forms simply because all living things need `energy` from nonliving things first .. Abundant amount of (Archaea bacteria) they observed during Permian extinction period are simply innocent bystanders –benefactors – of Permian environmental change which is primarily and potentially originating from `nonliving things of our universe` like intense and sustained volcanic activity and chemical energy(food) created by that activity ... Am I being clear enough to explain the fundamentals of living and nonliving things in Thermodynamic terms in our Universe ; particularly the –flow direction of energy(food source) for the living things ? .. Of course we re not talking `symbiotic energy exchange ` or ` energy flow in between living things like the lower life forms is being the main food source for the higher life forms ; in other words inter dependent food(energy) cycle , we are talking about the `Bottom of the totem poll ` when the nonliving energy is being transferred to the living Archaea life forms and its fundamental unilateral flow `direction` of energy for the fundamental principle of Maximum energy and Maximum Orderliness for the life forms , but not the other way around . For example ; for a good analogy for you ; like good old `Photosynthesis ` and the fundamental source of photosynthetic energy from our sun`s radiation , algae bacteria's simply can not create its own `light source` so to speak to sustain itself , the energy HAS TO come from the sun , without sun`s radiation and its energy flow through algae`s chloroplast there will be NO algae . So anytime you see increased `Archaea` bacteria during Permian extinction –that is simply a bystander- follower of the flow direction of energy to the living things , but NOT the creator of it`s own energy source to self sustain its life form and cause Permian Mass Extinction 252 Million years ago ... Thank you
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