After reading Part 1, and seeing how big the Columbia River basalt flood was, compared to ordinary eruptions, you might be thinking about turning survivalist, but please don’t head for the hills just yet.
We probably wouldn’t be here today without large igneous province (LIP) eruptions.
Destructive as they must have been at the time, LIPs probably did influence the evolution of eukaryotes — animals, vegetables (plants), and
minerals fungi — in ways that scientists are still trying to understand.
That’s why there will be many images of life in this post about awesome geology.
True, LIPs are cyclical (though irregular) and another one will eventually happen somewhere on land or in the sea. (Ernst et al.)
Fortunately for us, such catastrophes follow Earth’s clock, not our own. A sense of geological time is very helpful here.
Take Hawaii, for instance. According to plate tectonics theory, those volcanoes should sit along edges of the Pacific plate, like most Ring-of-Fire volcanoes, not out in the middle like that.
Kilauea and Mauna Loa apparently didn’t get the memo.
But intraplate volcanism is one of the defining features of a large igneous province. (Bryan and Ernst)
The Hawaiian Islands are volcanoes, not a LIP. What’s going on?
It’s impossible to say, given our short-sighted human perspective.
Taking the long view — that is, seeing things from Earth’s perspective — it’s possible (though not yet proven) that, about 100 million years ago, the broad head of a mantle plume — remember those? — reached Earth’s surface at this spot in the Pacific tectonic plate and erupted as an oceanic LIP. (Ernst et al.; Oppenheimer)
There’s not yet any expert consensus on whether such plumes can stay fixed in one place on Earth’s surface or shift around a bit.
We don’t need to worry about it other than to understand that hotspots don’t follow tectonic plate motion. One look at the Yellowstone track shows that!
Tectonic plates roll right over a mantle plume, which have deeper roots of some sort. (Black et al., 2021; Pastor-Galán et al.) The lava from plume eruptions piles up into a LIP only because it erupts before the plate can move on.
So, getting back to Hawaii, the reason why there’s no LIP there could be that, after the plume’s head had been used up millions of years ago, and while its much narrower plume tail continued to rise and build individual volcanoes (as it still does today), Pacific plate tectonic movements carried the bulky LIP on the seafloor away from that hotspot and eventually down into a subduction zone, leaving behind only a string of islands and seamounts to show that something unusual had happened. (Oppenheimer)
A massive, intense event, yes. And very rapid, in geologic terms — our planet is 4.6 billion years old, after all.
Volume and eruption rate are two more characteristics that make LIP eruptions so different from ordinary volcanism. (Bryan and Ernst)
For us humans, though, the making of Hawaii is playing out so slowly that we were attracted to the islands’ “eternal” beauty and settled down there many centuries ago.
Time out. You also might want to revisit this later, after we get to the Siberian Traps.
Of course, H. sapiens wasn’t around for that LIP, which might have been part of a cluster of Mid-Cretaceous Pacific plume eruptions (a little more on those later in the post). (Ernst et al.)
We also missed the Columbia River Flood Basalts.
If our luck holds, and if it’s true that such events occur on average every 30 million years (Ernst et al.), then the next continental LIP might not be due for another 14 million years or so.
So this is nothing to lose sleep over.
But what causes LIPs, and just how do they affect climate and evolution?
These are cutting-edge research questions actually but very relevant, considering that some researchers associate large igneous province eruptions, at least in time, with most of the Big Five mass extinctions. Yet other LIPs (including the Columbia River Basalts and Hawaii) apparently aren’t linked to global bottlenecks in evolution. (Black et al., 2021; Bond and Sun; Harris; Jahren; Kasbohm and Schoene; Keller; Oppenheimer)
Geoscientists need to build clear connections between each LIP and the forms of life that were on the planet at that time in order to find out what happened. This is an ongoing challenge for several reasons, not least of which is the need for high-precision dating of Earth’s stony archives. (Youbi et al.)
Until more breakthroughs occur, experts can only collect as much data about LIPs and mass extinctions as possible, make hypotheses based on computer models, and then seek a consensus.
Here is what I understand from reading a little of their work for the cat-evolution series. It’s by no means comprehensive or complete, but LIPs are interesting and this might also give you a little more perspective, from a Court Jester viewpoint, anyway, on the evolution of animals and of cats.
Let’s approach things from the top down, starting with surface effects today and then, in the next post, which connects supercontinents and LIPs, working our way deeper into the planet.
Do the same climate rules apply to large igneous province eruptions?
Here’s the sort of thing scientists take into account when looking at this question.
Reviewing Part 1 a little, CO2 emissions from today’s volcanoes help to keep the world warm through the greenhouse effect — volcanism begets “fire,” or a “warm to hot” setting on the global thermostat (another word for the net effect of many intricately connected Earth systems and their feedback loops).
Things switch over to “cool to cold” when an explosive eruption, such as the one Mount Pinatubo had in 1991, blows enough SO2 into the stratosphere to form a layer of sulfate aerosols.
This layer will soon rain out, but while up there it does prevent some sunlight from reaching the ground. (See Oppenheimer, Chapter 3, for a more thorough discussion of the effects.)
This “here’s how we covered Pinatubo” video is in another language, but it contains views of the famous eruption that you might not have seen before.
Magmas at different volcanoes have different chemistry. The Tonga blast on January 15th, impressive as it was, lacked enough SO2 to change global climate the way Pinatubo’s 1991 eruption did. (Oppenheimer)
Satellite monitoring during the early 1990s proved that sulfate aerosols are why global temperatures dropped about 0.5° C (almost 1° F) for three years after Pinatubo’s eruption. (Bond and Sun; Oppenheimer)
So, volcanoes today can warm the world or cool it down, depending on circumstances.
What wasn’t mentioned last time, to keep things simple, were all the knock-off environmental and biological effects from these two major but temporary climate changes, including but not limited to:
- Sulfuric and/or carbonic acid rainfall that damages plants, increases weathering of rock, and acidifies the ocean a little bit.
- Complex effects on photosynthesis.
- Livestock poisoning and groundwater contamination from toxic metals like mercury or halogens like fluorine.
- Disruption of weather patterns such as the regional summer cooling, winter warming, and changes in rainfall after Pinatubo’s eruption described by Oppenheimer in Section 3.2.2.
There’s material for several posts in all that, but here’s the big question: If you scale such things up for a large igneous province eruption, do they cause a major mass extinction?
It’s hard to answer, considering that the world’s youngest and best preserved continental LIP (Columbia River basalts) is about 16 million years old and the worse for wear. Solid data on LIPs are hard to come by.
One would think that such huge eruptions could harm life on Earth. Although linear scaling doesn’t always work, given the differences between LIPs and today’s volcanism (Mather and Schmidt), theory does sometimes bear that out.
But a real-life connection between LIPs and mass extinctions is hard to establish beyond any doubt, and not just because the geologic record can be challenging to interpret.
For instance, to get a little technical for a moment with Bond and Sun, who are talking about the intense global warming that a LIP might cause and how it might affect life:
Baseline metabolic rate might…be considered a key predictor of survivorship during extreme warming events: in theory, groups with sluggish metabolisms (e.g., brachiopods) should fare better than those with higher metabolisms (e.g., bivalves)…However, bivalves experienced a well‐below‐average generic extinction magnitude of ~60% during the Permian‐Triassic crisis…and also did relatively well during several other crises that are associated with warming.
In plain English, sixty percent loss is sort of a success story for the end-Permian extinction in which up to 96% of all known species on Earth disappeared (Keller) during the infamous Siberian Traps LIP eruption that we’ll check out in more detail later on.
Yet Bond and Sun report that the group of marine critters that should have done worse actually did all right for themselves in that and several other extinction events!
Life doesn’t always follow theory.
And check this out, also from Bond and Sun (emphasis added, along with the table they refer to):
Warming also indirectly damages ecosystems because it reduces the capacity of water to dissolve oxygen, and therefore promotes the development of marine anoxia, prolonged exposure to which causes death by asphyxia without selectivity…Anoxia is a proximal killer invoked in several mass extinction scenarios (Table 3.1)…ca. 1.5 million pilchards at Redondo Beach, California, [died] during a minor, but inescapable anoxic event in 2011…Perhaps in response, many animal groups have evolved specialists that tolerate and even thrive in oxygen‐poor conditions. These specialists can decrease their oxygen consumption and scale up anaerobic metabolism as required…such as during transient anoxic episodes, giving them a better chance of survival from such events, and, in theory, even thriving during mass extinctions caused by anoxia…
Ian Malcolm was right: life does find a way.
But it is always at great cost, whether you’re talking about those Redondo Beach fish that had no time to evolve, or the nonavian dinosaurs, or the many Precambrian and early Phanerozoic (a geologic time scale name for the last 450 million years) groups that perished while survivors went on to evolve into, among other beings, four-footed Devonian animals that walked out of the water and colonized the land.
I’m talking about things like the five toes/fingers per limb that descendants of those tetrapods take for granted today — but that anatomical detail must wait until the other series, about cat evolution, gets up to and passes through the end-Devonian extinction (which is associated with one, possibly two large igneous provinces).
Three LIPs, briefly
What are these eruptions like?
Oceanic LIPs are hard to study, but there are many known continental LIPs (check out Ernst et al., who try to list all the LIPs!).
Here’s what geoscientists think might happen in a continental LIP eruption.
The good news is that the whole world doesn’t melt — it’s regional.
The Siberian Traps, for instance, erupted about 250 million years ago in the possibly waterlogged (Black et al., 2021a) northern part of the supercontinent Pangea; plate tectonic movements as Pangea broke apart have since turned that area into north central Eurasia.
Now for the not-so-good news.
According to Black et al. (2021), after the first lavas of a basaltic LIP like the Siberian Traps erupt, typically hundreds to thousands of eruptions follow during the next ten thousand to a million years (yes), with a total lava volume of 100,000 to well over 1,000,000 km3.
The Siberian Traps volume is an estimated 3,470,000 km3. In contrast, the Columbia River LIP — the world’s smallest — contains about 670,000 km3 of basalt. (Ernst et al.)
Most of a typical basaltic continental LIP either erupts as lava or intrudes into the ground as magma sills and dikes in less than ten thousand years, which is slightly less time than what has passed since the last ice age ended. (Black et al., 2021)
Imagine what our lives would be like today if fissure vents somewhere — that’s how basalt LIPs erupt — had been pumping out 100 to 1000 km3 of Hawaiian-style basalt every year (Black et al., 2021), ever since human beings first settled down in communities.
Oh, we’d be used to it — and probably fearing the resulting climate change if the eruption ever began slowing down because that’s all we would ever have known — but how would we be living?
Would settling down and inventing agriculture, as we actually did after the ice age, even have been an option for us in a LIP-eruption world?
That’s the scale of change that LIPs conceivably can bring to the world, and also why a look at them is relevant to cat evolution.
But do LIPs really have such effects? And if so, how do the changes come about?
These are still unanswered questions but quite important ones in human terms as well as from the cat-evolution perspective.
LIP eruptions are definitely bad news, but their overall impact also depends on factors such as the overall size, eruption timing and dynamics, local geology, the magma plumbing system, and whether the eruption takes place on land or under the sea (which can act as a buffer). (Racki)
As I understand it, that Middle Cretaceous mantle plume cluster 150 to about 100 million years ago — likely including Hawaii as well as other LIPs (Ernst et al.) — might have had much worse effects globally if it hadn’t erupted at the bottom of the Pacific Ocean.
Here is another, sadder example of how important these extra factors can be.
Bond and Sun noticed something weird when they crunched numbers for the Siberian Traps eruption:
…[T]he total CO2 released by one of the largest continental LIPs of all time, the Siberian Traps, has been estimated to have been 30,000 Gt (Courtillot & Renne, 2003), 10 times the mass in today’s atmosphere. At today’s rate of anthropogenic emissions, it would take just 800 years to inject that mass of CO2, and while some might forecast the end‐Permian style global warming in the next 800 years, few would argue that the entire Siberian Traps were emplaced in such a short time. It has been noted that the volume of the Siberian Traps volcanics alone is insufficient to have generated global warming on the scale predicted…There must be a missing link.
Bond and Sun go on to discuss other things, like methane release, that might have boosted the greenhouse effect for the 15° C (27° F) rise in global temperatures that they associate with the Siberian Traps and the end-Permian mass extinction.
But then they report this, and I’m quoting them again for two reasons:
- Each possibility that they describe is a mind-boggling horror that I’d rather not try to express in my own words (emphasis added in the text to show these points).
- It’s not often that you hear highly cited researchers talking about “game changers” and “shifting the goalposts” in 2021.
I’m also adding a link with more information about those intrusions.
Sobolev et al. (2011) revised Courtillot and Renne’s (2003) estimate of the Siberian Traps’ CO2 budget dramatically upward when they suggested that recycled ocean crust may form up to 15% of [mantle] plumes, and this material would yield substantial amounts of CO2 during partial melting. Driven off ahead of the ascending magma, an estimated 170,000 Gt (nearly 60 times the amount in today’s atmosphere) of CO2 may have been released in a few, closely spaced blasts, with devastating results. Sobolev et al.’s (2011) model has an order of magnitude more CO2 than previous estimates being injected into the Permian atmosphere in a geological instant. This is a game-changer, but the goalposts had shifted several years earlier, when Svensen et al. (2004) suggested…thousands of Gt of methane released by organic‐rich sediments being baked by high-level intrusives…So-called thermogenic gases represent a potentially deadly additional source of methane and CO2…Svensen et al.’s (2004) theory soon found favor in the Permian‐Triassic community with suggestions that significant CH4 [methane…BJD] and CO2 was generated by intrusions into coal…and other organic rich sedimentary rocks…Svensen’s and Sobolev’s hypotheses changed the way we think about LIPs, and apparently (for now) provided the missing pieces to the LIP‐warming‐extinction jigsaw.
Here are some views of Siberian Trap sills and layers of organic sediments as they appear today:
That’s amazing: 252 million years ago, almost all known species on Earth died off simply because of a mantle plume’s chemistry (recycled ocean crust) and/or the type of bedrock it erupted through (carbon-rich coal and other high-organic rock formations).
Wait, put your survivalist kit back on the shelf! Please?
After all, it’s not news to us that —
Kilauea, 2018, by Honolulu Civil Beat
— we are all —
— in some way —
— at the mercy of natural forces much stronger than us all of the time.
The events shown above happen much more often than LIPs do, yet we don’t worry about those unless they are likely to affect us personally.
We develop monitoring methods to protect ourselves and help those caught up in the disaster any way we can.
Rest assured that we will do the same thing in the unlikely event of an oncoming LIP during humanity’s time on the planet. Oh, we’ll know: the precursors are too big to miss in this scientific age and they show up long before the lava arrives.
It won’t be pleasant (perhaps we won’t fly helicopters on Mars for a while, for instance, and maybe we’ll have to stop arguing and start cooperating in order to survive), but human beings are in a much better position to handle whatever comes than other forms of life were back in the day.
Also, on Bond and Sun’s table up above, you’ll notice that none of the other extinctions, including the other Big Five events, even came close to the end-Permian’s numbers.
You’re not in survivalist mode any more, I hope.
Compared to the other Big Five, that end-Permian extinction event was just a truly unlucky, bad break for life at the time, including the first known sabertoothed mammal-like predators. (Antón)
Sabertooths! Back then!
You see why the question “Where do cats come from?” is not as simple as it looks. There are so many hidden links!
Obviously whatever genetics makes saberteeth wasn’t wiped out during those awful days. Life found its way through the end-Permian disaster, and life has continued to find ways, because here we all are today.
Our world today is partly a result, somehow, of that end-Permian mass extinction, along with the two that came before it (Ordovician and Devonian), and the two that followed it (Triassic and Cretaceous), as well as all of the smaller background extinctions down through time.
There’s another point, too.
It’s true that all of the Big Five, except possibly the end-Ordovician mass extinction, are associated with LIPs. (Keller)
Yet for some reason, these large eruptions aren’t automatically a death sentence.
Take the Columbia River Flood Basalts. This LIP is very bland compared to the Siberian Traps:
Little is known about the Columbia River basalt flood’s effects on Miocene plants and animals in terms of long-term local climate, but no known global mass extinction is associated with it. (Harris; Kasbohm and Schoene)
There might have been cats around to experience it, though.
As the Columbia River basalts were polluting the region’s air, water, and land, pseudaelurine cats (perhaps from Asia) crossed a land bridge into North America, ending that continent’s 7-million-year-long “cat gap“! (Rothwell; Werdelin et al.)
The cats (and other wildlife and plants) were getting around because Antarctica was beginning to ice up. (The “Oi-1” on that graph above marks the first signs of continental glaciation down there, though it was nowhere close to its current state of deep freeze yet.)
Those first Antarctic glaciers (and perhaps others elsewhere on the planet) contained enough ice to lower sea level and to expose some land bridges.
Now what would you say if I told you that a large igneous province eruption occurred at the point on the graph where the red line, signifying warm global temperatures, turns blue and Antarctica starts freezing?
And that it is not associated with any major extinction?
That’s the third LIP for this section: northern Mexico’s Sierra Madre Occidental.
True, this mountain range doesn’t look at all like the Columbia River Basalts or the Siberian Traps.
It formed through explosions rather than lava flows. This rare type of large igneous province is sometimes called a SLIP: silicic LIP.
The Sierra Madre Occidental erupted right around the same time as that “greenhouse-icehouse” climate transition at the Eocene-Oligocene border almost 34 million years ago.
Worldwide, there were plenty of minor extinctions and major ecosystem changes, too, but these seem to be due to the global climate shifts, not directly from volcanic effects.
None of the Big Five mass extinctions happened then.
Few sources that I have read attribute the Eocene-Oligocene transition to the Sierra Madre Occidental eruption of a mountain range, and the supereruption swarm that was happening a little farther north.
That sounds surprising, but there are good reasons.
Notably, other major tectonic and volcanic events that could cause global cooling were happening elsewhere at around the same time (Bryan and Ferrari; Katz et al.; Lyle et al., 2005, 2008; Youbi et al.), and also because silicic magma tends to have less sulfur in it than basalt does and any stratospheric aerosols that formed, even if the eruption columns were loaded with sulfur, wouldn’t last long enough, at least in theory, to trigger a greenhouse-icehouse switch in Earth systems. (Oppenheimer)
But some researchers, notably Cather et al., suspect that all of this explosive volcanism was a major contributor to the global chill.
They argue that such massive quantities of ash probably fertilized the ocean, increasing photosynthesis and thereby drawing down atmospheric CO2 enough to help reset the global thermostat.
As well, Youbi et al. list some basaltic LIPs, going all the way back into the early Precambrian, that occurred at times of global cooling.
I know. We seem to have wandered far from Fluffy’s food dish, but consider this:
- Up until then, a group of carnivores called miacids occupied the predator positions in North America and Europe that cats now own. Wolves and dogs are descended from their namesake, Miacis.
- Cooling caused glaciers, taking up enough water to lower sealevel.
- A shallow sea that had covered much of Central Eurasia until that point dried up, and a bunch of Asian critters, including feliforms, followed the setting sun into the west.
- Those critters, particularly the feliforms, apparently were better suited to the new dry, cool conditions than Europe’s miacids and outcompeted them so dramatically that the resulting change in the fossil record is called The Enormous Break, or Grande Coupure.
- During the adaptive radiation that followed, one of these feliforms evolved into the Dawn Cat, Proailurus.
We were close to the kibbles all along!
These little known but vitally important connections are what makes writing about cat evolution tough — and also a LOT of fun.
This is a good place to end the post, but consider yourself warned: next time (not necessarily next Sunday, but I’ll try), we’re going to get into continents and supercontinents, a/k/a the stage that cat evolution has played out on for billions of years.
LIPs are associated with supercontinents by many, though not all, researchers.
Yes, supercontinents, plural. The one we’ve all heard of — Pangea — is just the most recent.
Depending on who you consult, Earth may have had several supercontinents, going all the way back to the early Precambrian.
That must have influenced evolution in many ways (spoiler: as one example, according to one hypothesis, continental minerals and elements washed into sea from supercontinent Rodinia at just the point in evolution when our distant eukaryote ancestors were ready to use them in developing bone and other hard parts).
Enough for now. Meet you on Columbia/Nuna!
Featured header image: Surapong/Shutterstock
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Oppenheimer, C. 2011. Eruptions That Shook the World. Cambridge: Cambridge University Press. Retrieved from https://play.google.com/store/books/details?id=qW1UNwhuhnUC
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Prothero, D. R., and Heaton, T. H. 1996. Faunal stability during the Early Oligocene climatic crash. Palaeogeography, Palaeoclimatology, Palaeoecology. 127:257–283.
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Youbi, N.; Ernst, R. E.; Mitchell, R. N.; Boumehdi, M. A.; and others. 2021. Preliminary Appraisal of a Correlation Between Glaciations and Large Igneous Provinces Over the Past 720 Million Years. Large Igneous Provinces: A Driver of Global Environmental and Biotic Changes, 169-190. https://agupubs.onlinelibrary.wiley.com/doi/10.1002/9781119507444.ch8
Note: I am centralizing sources here that I dug up for this post together with those that I read a few years ago covering the Eocene-Oligocene transition, the Sierra Madre Occidental, the ignimbrite flareup and related topics, and some miscellaneous. As sparingly as possible, mainly for the part about Antarctica and Eocene-Oligocene extinctions and ecosystems, I drew on some of those older sources without going back to look up the specific citation.