Volcanism And The Nastiest Extinction Ever
Researchers have finally determined with unprecedented confidence that extreme volcanism 252 million years ago is the likeliest cause of the greatest mass extinction the world has seen.
A quarter billion years ago (give or take a week or so), the world was not in a good way. It was undergoing the greatest series of extinctions that had ever happened. That record still stands today. This event goes by many names, The Permian-Triassic Extinction Event, The Great Permian Extinction or most floridly perhaps, The Great Dying. And dying is exactly what was happening.
When it was all said and done, here’s some of the horrifying numbers:
- 96% of all marine species died
- 70% of all land vertebrates went extinct
- It’s the only mass extinction of insects that probably ever happened
- Almost all the trees died
Such a cataclysmic event resoundingly shut the door on the geologic periods known as the Permian and ushered in the Triassic which clearly had a lot of ground to make up. It also ended the final chapter of the concurrent but more broadly defined Paleozoic era and started the Mesozoic.
Of course, the most pressing question regarding this event is: What the hell caused such a thing?
Finding clues to answer this is understandably difficult. It’s quite an overstatement to say that the trail has gone cold since a quarter billion years have passed. It’s probably more accurate to say that trail is near absolute zero. Yet science loves a challenge and can often glean vast amounts of information and possibilities from the most unsuspecting data. Over the decades many theories have waxed and waned to explain some of the significant yet ambiguous data that was being found including…
- A very large asteroid or comet impact
- Volcanism on steroids
- A Supernova. These can certainly cause global-scale catastrophes
- The formation of the supercontinent Pangea
- The sudden release of methane perhaps caused by a super-exponential bacterial bloom or other causes
- A combination of any of these
Extensive volcanic eruptions (magmatism) have long been a good candidate for the Great Dying if for no other reason than an amazing geologic feature in Russia called the Siberian Traps. This area in Siberia saw a truly outlandish amount of volcanic activity around the time of the Permian extinction that is still obvious today. I’m not talking about your nice cone-shaped volcanoes or even your super-volcanoes. I’m talking about what’s called a flood basalt eruption. Basaltic lava has a very low viscosity so it doesn’t build up a cone; it spreads far and wide creating massive “flood basalt provinces.” It also doesn’t shoot its wad by exploding catastrophically with a relatively brief follow through.
Flood basalt eruptions are a different beast entirely. These can be caused by actual fissures in the earth’s crust. If you saw one you might see curtains of lava going high into the sky from horizon to horizon. They could also erupt for decades, then stop, then start up again. The eruptions that caused the Siberian Traps could have erupted intermittently for perhaps a million years from multiple fissures. Think about that. The end result could have paved the entire United States…a kilometer deep!! Lava of course isn’t the only byproduct of such volcanic activity and it’s not the cause of the Great Dying; It was the gas release. These toxic gasses would have caused a plethora of nasty effects such as:
- Devastating acid rain
- Destruction of the ozone layer
- Blotting out the sun.
- Increased glaciation lowering sea level which killed marine life and released methane
- Methane could combine with C02 and cause a runaway greenhouse effect
Oh, btw, anyone on earth can see with their own eyes the result of flood basalt eruptions right where they are. Just look at the moon. Those dark patches (or maria) are the result of this type of eruption.
Seth Burgess, a postdoc at the U.S. Geologic survey said:
“It’s literally a singular event in Earth history…It makes Yellowstone … look like the head of a pin.”
As promising as this theory is, it has always been difficult however to precisely determine when the volcanism occurred and compare that to when the extinctions occurred. After all, the volcanism could have been incidental or just an accessory to the true cause of the loss of life. Well, now we have a much better idea.
Massachusetts Institute of Technology (MIT) researchers have determined that the timing of the eruptions was just right to account for mass extinction. The lava and gasses started belching from the earth about 300,000 years before the extinction. After the death toll was essentially complete, the nastiness continued for another half a million years (just to be sure I guess).
Burgess, who received his PhD from MIT last year also said:
“We now can say it’s plausible,…The connection is unavoidable, because it’s clear these two things were happening at the same time.
They arrived at this conclusion after examining over a 100 kilos of rock arduously collected and brought back from the Siberian Traps. They then dated the rock using a technique called uranium/lead geochronology. This involved looking at crystals in the rock to compare the ratio of lead to uranium. Freshly made rock crystals like this have some uranium but no lead. Over the eons, the uranium slowly and predictably decays to lead. That ratio then is a distinctive marker for how old the rock is. The final step was to compare these dates to the dates previously determined for the extinction itself which, importantly, used the identical technique.
Richard Ernst, a scientist at Carleton University in Ottawa, Ontario said:
“This paper nails it…this is the ‘smoking gun’ for this large igneous province being fully correlated with the extinction. At this point, additional dating and other studies will simply provide more details on the link.”
So what does the future hold?
Like Ernst said, it’s a matter of filling in the details. We still need to flesh-out the timeline more accurately. Perhaps the eruptions were relatively meager for a long time until a massive and quick release did all the major damage. Maybe it was a steady slow accumulation until the biosphere just said “Fuck it, I’m outa here”.
I know what you’re thinking, no matter how it happened, I’m very glad it did. Two of the carnivorous survivors to this catastrophe, the cynodonts and archosaurs sauntered into the newly minted Triassic Park to find a world with many new open niches just waiting to be filled. The archosaurs spread out and evolved into the world-dominating dinosaurs and we know what a fantastic run they had. Their dominance forced some of the cynodonts into niches (nocturnal insectivores) the dinos weren’t too interested in. It was in the so-called “nocturnal bottleneck” of those niches that mammals evolved many of their distinctive characteristics.
Our run has been interesting as well but that chapter is hopefully far from over.
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