Russian volcanoes fingered for Earth's largest mass extinction The largest mass extinction event in Earth's history may have been driven by incredibly violent million-year long volcanic explosions that destroyed the ozone layer some 250 million years ago. Scientists call it the Great Dying, where almost 90 per cent of creatures perished at the end of the Permian era. Animals in water and …
"These eruptions were yuge, bigly yuge. Some say they lasted a million years, some say ten million. I dunno. Beats me. But a yuge eruption lasting ten million years seems to me proof that Crooked Hillary hid her emails in the earth's crust. Why isn't Jeff Sessions demanding we investigate that? I spoke to the Russian Premier, a great man, great man, and he has no problem with our teams investigating all we want when it comes to Siberian rocks and Hillarycanoes."
Good post. Part of the problem is that the evidence no longer exists. Take Lake Baikal. It exists as part of a rift valley complex. Rift valleys are normally spreading centres between two plates (like the rift valley in Africa, the mid atlantic ridge, etc, etc). There's no plate boundary, however. There might have been, but due to subduction, etc, etc, we'll never know.
The time scale, however, does coincide with the break up of pangaea, however...
Some rift valleys are found on spreading margins - such as that along the MidAtlantic Ridge; but most are intraplate features created by an upwelling of hot Mantle under a continent. A really good example is the East African Rift Valley which is pulling the African Plate apart; but doesn't seem to have quite enough umph to actually break the plate and create new ocean floor.
Closer to home, there are nice rift valleys in the German Rhine region; the Midland Valley in Scotland, the North Sea and a hidden one running north-south under the West Midlands.
"there are nice rift valleys in the German Rhine region; the Midland Valley in Scotland, the North Sea and a hidden one running north-south under the West Midlands."
On the other side of the Atlantic there's the Reelfoot rift, which usually pops every couple of hundred years with a series of magnitude 8+ tremors. The last set were centred around the town of New Madrid. The USA has only just started waking up to the scale of the issue across the midwest in the last 25 years (the biggest natural disaster in terms of widespread loss of life, building destruction and sheer cost they're realistically facing is another New Madrid earthquake swarm, not Calfornia quakes/Cascadia Tsunamis or Yellowstone). With Trumplethinskin in the hot seat and FEMA et al being cut back, Puerto Rico/Haiti is likely to be the kind of scenario that may unfold.
It's worth noting that major river courses tend to roughly follow the path of deep faults like Reelfoot. It's one good reason why putting things like nuclear power stations alongside them may not be such a smart idea.
The dynamic of these huge events is pretty well understood as being related to Mantle plumes which are superheated columns of rock (not magma) rising from close to the Core/Mantle interface. They rise through the Mantle as relatively narrow features, but as they reach shallower levels they form mushroom-cloud shaped bodies of rock. The reduction in pressure is enough to partially melt the head of the plume; meanwhile the impact of the plume on the lithosphere causes it to bulge upwards, thin and fracture allowing the magma to pour out as flood basalts.
As you say, the Deccan is probably linked to the extinction of the dinosaurs; a massive decline in biodiversity (especially in the oceans) and a wildly-changing climate and acidified rainfall were all occurring long before part of Mexico was turned into a crater. Right now, that plume is driving the volcano on Reunion in the Southern Indian Ocean - but the good news is that once the head of the plume has been exhausted, the long tail only provides a relative trickle of melt.
The most productive plume on the planet right now is the plume that created the Antrim Basalts in Northern Ireland is now driving most of the volcanism in Iceland (the MidAtlantic Ridge is a relatively small contributor to Icelandic activity); but the most impressive is the one under Afar in Ethiopia which is pushing the whole of East Africa more than a kilometre into the sky and driving the Africa Rift Valley - although it probably isn't strong enough to rift Africa into two.
In theory, we could see any emerging plumes long before they arrive on the surface through technologies such as seismic tomography and their effect on local gravitation; but the good news is that there is no obvious threat from a new plume for the immediate geological future.
The threat is from the tails of existing plumes, which although they only ten to produce a fraction of a cubic kilometre of melt each year, can occasionally produce monstrous volumes of magma - such as our old friend the Icelandic plume which produced 18km3 in the Eldgyá eruption of 939CE; depressed Northern Hemisphere temperatures by 2C and probably inspired the Viking idea of Ragnarok; and then vomited up a further 14km3 from nearby Lake during 1783-84; creating a famine that killed a quarter of Icelanders, poisoned more than 20,000 people in England and probably contributed to a complete collapse of the Indian and Chinese monsoons. If they were to happen today, the death toll across the World could be unimaginable.
Just to put those into context, after 65 million years of erosion, the Deccan contains more than one million km3 of lava. Magnetic evidence suggests most of it was erupted within a span of 20,000 years which included several prolonged episodes of inactivity. A Deccan-like eruption would be the end of us.
It would however be a beautiful way to go....
It's a plume-driven volcano and it will probably have major explosive eruptions in the future. On a historic scale, a repeat of one of the cataclysmic eruptions from Yellowstone (or indeed its more mysterious southern cousin, Long Valley) would be devastating and cause huge hardship for the Northern Hemisphere. However, chances are on a human timescale, future activity will be confined to the caldera; and on a geological timescale, even caldera eruptions pale in comparison to flood basalts.
Though, the fading plume that drives Yellowstone was responsible for the magnificent Columbia flood basalts of Washington and Idaho. I heartily recommend a trip to anyone who wants to be awed by a landscape. (And Yellowstone itself is simply jaw-dropping).
Jack of Shadows: "We need to figure out what the dynamic is here that initiates million year long volcanic events."
Interesting question. Geologists occasionally muse about the way surface and sub-surface shockwaves propagate from major impacts, in particular the fact that, as they radiate around the globe from the impact point, they come togather again at another point on the antipode—i.e. on the other side of the planet (so, for example, London's antipode is a few hundred km south-east of the southern end of New Zealand). Some modelling (though I'm not sure of the quality, so far) suggests that this re-focusing of the shockwaves may have major effects, such as earthquakes, possibly fractures of the crust, and therefore maybe precipitating volcanic eruptions.
While it's a reasonable hypothesis, so far as I'm aware it remains unproven, particularly as to the violence and ultimate significance of any antipodal seismic disruption. By contrast, it may be that shockwaves can have more devastating effects closer to the impact point, for example as they refract through different denstiies of material. In other words, it's possible that the eruptions generating the Siberian Traps were caused, or made worse, by an impact, but the latter need not necessarily have been at the antipode (which would have been Antarctica today, hence some early interest in the Wilkes Land Crater features, which I think are now known to be too young to be guilty, if indeed they are impact features at all).
I hope that a good few excited geology postgrads are looking, firstly, at the historical evidence: it can actually be quite difficult to find really old impact points, and then determine that what you've found really was caused by an impactor rather than being a perceptual artefact or—like Silverpit—possibly rock collapsing due to salt exfiltration (also, viz the mention of WLC above). Secondly, let's hope they'll also be hooking up with some seriously powerful computing power to more accurately model and understand how impactor shockwaves propagate through the Earth's quite complicated mixture of layers and densities. There is an awful lot yet to be learned about this subject.
The problem I have with the idea that eruptions can be initiated by antipodal shock is that it doesn't account for the presence of eruptable lava at that antipodal point: whilst the shock might very well create new faults, which might make it easier for any existing eruptable lava to reach the surface and erupt, it won't create that eruptable lava - it would already have to be there.
A couple of things seem to be misrepresented in the article though, seemingly to sex it up a little bit:
"The scale of this extinction was so incredible that scientists have often wondered what made the Siberian Flood Basalts so much more deadly than other similar eruptions".
Scientists quite probably did wonder about the scale of the extinction, but only until they discovered the scale, both in size and duration, of the Siberian Traps eruption, then it pretty much did make sense.
And:
"But after the volcano exploded..."
This suggests a localised Plinian type of eruption, ending with a single, or short sequence of paroxysmal explosions, rather like Krakatau or Mt St. Helens, and which are associated with plate-boundaries and subduction zones, whereas it seems pretty certain that the Siberian Traps eruption(s) were of long duration, effusive and non-localised. This is not to say that there wouldn't have been any 'explosions' but they would have been relatively small and pretty insignificant in the overall scale of the Siberian Traps eruption.
A link between the Chicxulub impact and a massive increase in the volume of the magma erupting from the Deccan has been proposed in:
Keller, G., 2014. Deccan volcanism, the Chicxulub impact, and the end-Cretaceous mass extinction: Coincidence? Cause and effect? Geological Society of America Special Papers 505, SPE505-03. https://doi.org/10.1130/2014.2505(03)
Keller proposes that the Mantle could be fractured by a massive impact allowing melt to migrate more rapidly to the surface and produce cataclysmic amounts of lava. It's an intriguing theory with a lot to commend it, though it is clear the Deccan was buggering the planet well before the impact. The biggest problem is dating the Deccan itself; many of the lavas have suffered low temperature metamorphism or chemical weathering which have altered the feldspars normally used for K-Ar and Ar-Ar dating.
Annoyingly, the KPg iridium anomaly is not found in the Deccan. A few localised iridium anomalies have been found in the West of the province, but it is generally thought they represent concentrations of the element from terrestrial weathering.
I still think we need a time machine.
One of the hard things about seismology on a global scale is the wave front of a shock is seriously blurred and diffused by the time(s) it gets to the other side of the planet. Even something as massive as Chicxulub would only be a medium to large earthquake and it would be very unlikely to act as a trigger to a volcanic eruption.
Alvarez was using the older K-Ar dating method for his research.
It's now clear that this is not reliable in the Deccan as many of the feldspars used for dating have either been chemically altered by hot groundwater after the lavas crystallised, fractured - allowing argon to escape, or weathered on the surface. This has the effect of producing abnormally young K-Ar ages for the lavas which are in conflict with the fossil data found in sediments between individual flows.
More recently, geologists have moved to Ar-Ar dating on isolated, cleaned feldspar crystals which produce much more consistent dates. The new dates show the most prolific part of the Deccan all lie within the magnetic episode called C29r (66.398 - 65.688Ma) which straddles the K-Pg boundary (66.043 ± 0.043Ma) - although the position of the boundary inside the Deccan is not clear.
The Deccan traps _are_ wrong for the K-T event but they fit for the extinction trail and evidence of biosphere poisoning leading up to it.
The part that causes so much argument about Chixulub is that it's not large enough to have caused a mass extinction _by itself_ even given the location where it hit (shallow limestone sea), but a basalt flood event plus asteroid strike certainly would do the trick.
Peter Brannen has written a very interesting and readable account of this and the other 4 mass extinction events that have taken place over the history of life on the planet (The Ends of the World). It is amazing just how much can be learnt about the Earth's history from billion year old rocks.
The book is a bit like the Total Perspective Vortex from the Hitchhikers Guide to the Galaxy, highlighting the tiny amount of time that humans have been on the planet in the perspective of its 5 billion year history, as well as the fragility of life.
"And is why we really, really, need to find some way to send at least some of us somewhere else."
Why? To preserve the species? Are we really all that worth it? Evidence would suggest otherwise. Sure, some individuals are noteworthy ... but as a whole, humans are greedy destructive bastards who refuse to play nice with others. Sadly, I suspect we've stopped evolving and are yet another evolutionary dead end.
Why? To preserve the species? Are we really all that worth it?
Nominate some better candidates and I'll consider your rationale. Notwithstanding the worst that humans can do, at tour best, we're clever, cooperative, caring and altruistic. I think making an effort at preserving the species for its better qualities is very sensible.
I think you can add at least hens, cattle, sheep, probably horses, cats & dogs to that list.
And numerous species of plants, fungi, protozoans, etc. At least if the metric is something like population size or outlasting niche competitors.
If you want to go maximum Dawkins, you could argue that humans have been very bad for many genes (thanks to the various extinctions we've caused), but great for a lot of others. We've even moved some genes into genomes they never would have gotten into otherwise.
(Not that I'm recommending going maximum Dawkins. Even in an emergency, I can't recommend more than 0.7 Dawkins.)
Nominate some better candidates and I'll consider your rationale.
At this point, there aren't any better candidates. If we look at this being births and deaths of life, perhaps what was considered an advanced civilization did exist before the event. We don't know and may never know. At it its, we're the best currently. In a million or billion years, it may well be something else.
"At it its, we're the best currently. In a million or billion years, it may well be something else."
Unfortunately, there can be no post-human technological civilisation on this planet. Indeed, should this human city culture fail there would be no coming back. No recovery. No second chance at the stars.
All of the free, easy to grab energy sources, with the exceptions of wood and horse-equivalents are gone, used up, converted into City, treasures and CO2. Bootstrapping a second city-culture level society to the level that would allow it to take the stars can never happen as there are no energy sources to power it.
Solar, wind, tidal, nuclear and geothermal power plants need a preceding base of coal and oil powered technologies to get them up to a useful point. Once humans, once *this* human culture has used up the oil and coal there will be no way of *starting* such a base.
Life on Earth has one chance of getting off-world. We're it. We have one chance of getting off this word and it is *now*.
We're not going to do it. The era of manned off-world activity is dead. The Dream of Stars is dead.
All of our songs, all of our stories, all our splendid heroes, nasty villains, kings, cooks, magicians, wizards and writers will be lost forever. All the future of the cosmos will be silence.
Once this civilisation collapses there is no climbing back.
Why? To preserve the species? Are we really all that worth it?
Ultimately, our only worth is so that some future squid creature can create a work of fiction about creating a safari park inhabited by creatures whose DNA was protected by multiple layers of fake tan...
[...]as a whole, humans are greedy destructive bastards who refuse to play nice with others[...]
I'd like to disagree with you, but the evidence is on your side.
However;
Sadly, I suspect we've stopped evolving and are yet another evolutionary dead end.
As long as people are still breeding in the traditional way, we'll still be evolving. That doesn't mean we'll be (eg) getting smarter, as the evolutionary pressures might be pushing us towards developing a smaller brain (which might use less food for example), but we are still evolving.
Evolving doesn't mean constant improvement.
Try reading Vonnegut’s Galapagos. The premise of the story is that nature screwed up and gave us too big of a brain. However, she corrects her mistake, and we (d)evolve to be the critter she Intended us to be: one who spends everyday simply laying in the sun, eating, farting, and having sex, noting more.
And is why we really, really, need to find some way to send at least some of us somewhere else.
Not that it would help in this case, since Mars barely has an atmosphere let alone an ozone layer. We'd be far better off building shelters on Earth rather than Mars. It'd be much cheaper, more certain, and capable of protecting many, many more people than we could ever send into space.
It's worth putting that 'fragility of life' quote into context too: life survived, every time. And that was without having the advantage of intelligence or technology.
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