Sustainability
Environmental Impact of Super Volcanoes
Moderator: Tonight we're joined by Clive Neil. Clive got his PhD in 1986 from the University of Leeds. And he describes his research as‐‐ he uses petrology and geochemistry to investigate the environment, from planetary differentiation to heavy metal pollution. His‐‐
his research is not constrained to earth. As I found out he uses‐‐ he studies the moon. He uses mars rocks in his work. He has so far edited two books. And I find most impressively is he's got 83 peer‐‐ peer reviewed publications in journals such as science. So, tonight it's my pleasure to introduce Clive and his Origins and Environmental Impact of Super Volcanoes.
Clive Neil: Thanks Jim. [Applause] I would save the applause until afterwards just in case. I got that jetlag thing going on coming from Indiana. So, tonight I‐‐ I'm going to talk about super volcanoes and that's a very sexy term these days because you put super in front of anything, it means it's better. This time it could mean that it's worse. 1
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I‐‐ I'll leave you to‐‐ to actually judge that because I'm here on behalf of the scientific ocean drilling community. And we have been drilling on this ship‐‐ is from the U.S. the JOIDES Resolution, basically for the last 10 or 15 years, from the Ocean Drilling Program to now the Integrated Ocean Drilling Program where there are actually 3 platforms, the U.S. ship JOIDES Resolution right here, the CHIKYU from Japan, which is a riser vessel. This is a much bigger vessel that will not fit under the Golden Gate Bridge because its drilling derrick is just a‐‐ it's a monster. We affectionately call that one the Godzilla maru because it‐‐ it's just big. And then we have the European consortium that run what we call mission specific platforms. And the first Integrated Ocean Drilling Program expedition was to drill a transect across the North Pole. So, this involved converting an ice breaker to a drilling ship and then taking sediment cores across the North Pole to look at climate change that was recorded in those sediments. So, basically what it comes down to is we're using the drill cores to understand what happened in earth's past. And trying to attribute that to well was it due to some of these super volcanoes? Now, these I've put here these I'm going be interchanging super volcanoes with LIP, which is a Large Igneous Province. And I'll get on to what that definition is in a minute, but if I flip flop back and forth I apologize. It's‐‐ it's the jetlag thing again; that three hour time‐‐ time difference. 2
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So, here we've already flipped, we'll flop again in a minute. Just to give you an idea of my experience, I've done field work in the Solomon Islands. They're in the Southwest Pacific. We have Cape York in Queensland from Australia here, Papua New Guinea. And then we have this monster Large Igneous Province called the Ontong Java Plateau, which is now butted up at a subduction zone here. We have lots of earthquakes there, lots of volcanoes. But, we‐‐ we're fortunate because we now have portions of the Ontong Java above sea level. And they outcrop in these islands. Here's Guadalcanal, that's probably the most famous of the Solomon Islands. 3
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And I've done field work in 93 Malate. And you can see here, it's obviously basalt because it's black rock and I stand out quite nicely. 4
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Then in 95 and 96 in the‐‐ on the island of San Cristobel, which is here, where we find this purple coloring is outcrops of the Ontong Java. And we spent quite some considerable time, two field seasons basically in being wet because you're in a tropical rainforest. The only outcrop are in rivers that you can see here. So, you have to go up and down rivers. Two weeks into the first field season out there I woke up one morning and I looked down at my forearm and I'd gone gray overnight. Every single‐‐ all the hairs were‐‐ were completely gray. And I thought how long did I sleep type of thing? And I went like that and it was mold. I was going moldy because I'd been‐‐ I'd been wet for too long and it's a very humid environment. You get a cut on your leg, if you don't catch it within 10 minutes it'll go septic. It's quite a challenging environment to do field work in and when I pointed this out to the guide, some of the locals here, this is Cromwell Capoto, he just laughed at me. He says, "Yea the white man doesn't last very long in‐‐ in‐‐ in the rainforest." And he's absolutely correct. The other thing that we‐‐ another experience that we had here was a magnitude 7 earthquake that woke us up one night. My colleague here John Mahoney from the University of Hawaii said to me one day, "Did you feel the earthquake last night?" I said, "No, I slept right through it." He says, "Well, it was about a 3 or 4." He says, "Quite‐‐ quite strong." And I said, "I‐‐ I go to sleep, it's going to take quite a big one to wake me up." Well, the next night magnitude 7 went through, threw me out of my camp bed. And its dead‐‐
after an earthquake it's just completely dead silence apart from John Mahoney saying, "Did you feel that one?" [Laughter] No kidding. 5
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So, field work was challenging. It was exciting. It was fun. It's a great way to lose weight, which I probably need to go back out to the Solomon's again. You drink the water straight out of the streams because they‐‐ everybody lives on the coast and it's just pure water. Well, I drank‐‐ so, in 96 I drank some water that was tainted because there was a hunting party up stream. And let's just say they were a little free with their organics. I couldn't eat for four days. I could just drink water. And I made good use of the rainforest when I needed to. And I went from 230 pounds to 188. It was a great way to lose weight, but my wife made me‐‐ basically hospitalized me when I got home. I got off the plane and she just‐‐ the look of horror on her face of what the heck has happened here. But, apparently I looked like I just got back from Belsen. 6
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So again, we have the drilling‐‐ three ocean drilling legs to different Large Igneous Provinces. This one is in the Southern Indian Ocean leg 183 to the Kerguelen Plateau and Broken Ridge. And I give you here, a picture taken from the bridge of the JOIDES Resolution. And I was on‐‐ on‐‐ on the bridge talking to the captain and all of a sudden the captain went uh oh. I said, "What's the matter Captain Tom?" And he said, "Look at the barometer." And it was doing this, plummeting. Then the waves started up. And this bridge is 50 feet above the sea. And we're looking up at the wave coming in. He called the‐‐ the drill platform and he said, "You have to stop drilling. You need to pull up the drill string because the heave compensator will be maxed out. We won't be able to take the heave. And we'll just break the drill string and lose it." And this went on for about 12 hours. And that's when you go‐‐ when you go to bed at night, you put your life jacket under the mattress in your bunk, if you're on a top bunk to roll you into the wall because you will roll out and hit the floor if you don't do that. 7
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That was in 1998‐99. It was over Christmas. And then 2000 I went to the Ontong Java plateau. You could see the contrast in the sea conditions between the two. This is from the sublime to the ridiculous. It was incredibly hot, but even though this was summertime in the Southern Hemisphere we still had a white Christmas at leg 183, little bit of snow on one of the‐‐ one of the life boats. 8
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And then, 2001 I went to the Emperor seamounts, which is the extension of the Hawaii chain going up to the Northwest Pacific. Interesting thing happened here. These are the two co‐chiefs right here, these two chaps. And we were supposed to start at Meiji Seamount. It's one of the oldest seamounts. It's the closest to Russia. It's in Russian territorial waters. And we left from Japan, but Japan did not grant the Russian scientist a Visa to enter the country and let him join the ship. So, Russia says, "You're not coming into our territorial waters." Okay, fair enough. That's the way politics works. Forget the science, we just do politics. So, we started at the Detroit Seamount, that's a very interesting Japanese emperor named Detroit. I think it's named after a battleship rather than emperor, but it is in the Emperor seamounts. And it's just outside Russian territorial waters. But, we had to do a seismic line on the ship to actually figure out where we're going to drop the drill string. It gives us pinpoint‐‐ where we can do it. What are the hazards? So, it just so happens that we're running the seismic line and the ship is heading straight towards Russian territorial waters. And all of the sudden there's a big seismic return from the middle of the water column. It's a Russian submarine. And next thing, you see these little vibrations come at low level‐‐ low frequency communications to the surface. Low and behold we see on the radar a surface vessel coming in intercept mode at 20 knots. And the captain says, "I'm not this‐‐ this is not good." So, he broke of the seismic line and as soon as he broke it off, the surface vessel broke off and we didn't see the submarine again or hear from it. And I slept through everything, as always. I was off shift and I just‐‐ you missed all the excitement. Well, isn't that always the case? But, if we would have boarded by the Russian Navy I think I would 9
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have been better off sleeping.
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So, what I'm going to talk to‐‐ talk about tonight is give you a primer on how we think the earth works. And then we're going to talk about generation of super volcanoes of LIPS because they don't really fit into the general model. We're going to look at the environmental impacts of‐‐ of these Large Igneous Provinces. And we're going to end up looking at just a quick couple of examples. We've got Iceland, which is an active super volcano. It's a country, but it's a big volcano. And then we've got Yellowstone, which is a little closer to home. 10
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So, in terms of how the earth works we've got our basic model. And I have to admit when I started learning geology I wasn't taught plate tectonics because it hadn't been thought of yet, which is a little depressing. So, we have a bunch of these different plates and you can see here, this shows where the major volcanoes are in the world. And these show where the major earthquakes are and you can see that they coincide with plate boundaries. So, we have a bunch of these different plates jostling around on the surface of the planet, bumping into each other and that's where we get our earthquakes. That's where we get our volcanoes. 11
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So, we see that these plates are actually made up of both crust and a little bit of mantle. We have a basic subdivisions of the planet, the crust that we're standing on and we go to the mantle, we go to the core. And with‐‐ the‐‐ lithospheric plates are made up of a little bit of mantle stuck on to some crust here.
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And we end up with basically three types of plate boundary. We have a divergent boundary where we get magna and crust generated in the mid oceans. And you can see them here coming up and all over the oceans. That's where we create oceanic crust. 13
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Then we have convergent boundaries. This is what we have along the Pacific Northwest, where we have oceanic crust being pushed underneath or subducted beneath continental crust. And that comes with a lot of volcanoes. There are a lot of volcanoes here too. 14
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Then we have transform faults and again San Andreas is probably the most famous transform fault or as I said in‐‐ to the class I lectured today is‐‐ New Zealand has pretty‐‐
pretty impressive transform plate boundary as well. Just ask the folks from Christchurch when their city fell over the other day or the other year. 15
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The mantle itself is about 3000 kilometers thick from the bottom of the crust down to the mantle. And it's made up of this rock we call peridotite. If you melt it you generate a basalt just as you would get of a Hawaii volcano. 16
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And again, we can actually look at how seismic waves propagate through the mantle to look the properties and different divisions. And we can see that if you heat up this peridotite it becomes plastic and it starts to flow because we've got a great temperature differential from the top of the mantle to the base of it at the core mantle boundary and heat is continually escaping. Heat continually escapes through convection and that's what drives these lithospheric plates and they jostle around for position with each other and generate earthquakes, volcanoes, so on and so forth. 17
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And again, these changes in‐‐ in temperature are important because not only can it cause convection, it can actually cause masses of that mantle to just rise in a point source of a‐‐ a material. 18
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So, what are super volcanoes or what are Large Igneous Provinces? Why do we care? While these actually don't really fit into a plate tectonic model directly, it's difficult to see. We can observe. We can go out and map and we can quantify the amount of lava that comes and it forms one of these Large Igneous Provinces. And you can't do it with a common or garden volcano like Mount Rainier or Mount Hood. It's not big enough. It doesn't do it. So, these are a big question mark then and as we study the planet and how it works as to what exactly‐‐ how exactly do they form? We‐‐ we see here that they are typified by what we term flood basalts. Lots of lots of lava eruptions that come out exceedingly quickly, very thick lava flows. And then they end up where they sort of tail off and we end up with these little tails that wag after these big plume or these big heads of flood basalts. And things such as Hawaii very long lived point sources of magmatism that occur throughout the crust‐
‐ throughout the surface of the earth. 19
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So, if we look at a map of LIPS, we have here what we termed the flood basalt for transient events in red and then the persistent or long lived events in blue. And you can see they're dotted around the‐‐ the‐‐ the world, they're on continents. They're in the oceans. They may coincide with plate boundaries, they may not. They really don't care. So, it's difficult to sort of‐‐ you think back to the first couple of maps, we've got the plates and the major volcanoes and they seem to be clustered around the plate boundaries. These really don't care. They make a habit of plate boundaries such as Iceland that‐‐ that forms a‐‐ that's right on the Mid Atlantic ridge. But, it's much more active than a mid ocean ridge because it has built a thickness of magma so now it's above‐‐ it's above the surface of the water. It stands high, tall and proud and puts up the‐‐ some quite spectacular volcanoes. 20
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So, how can we explain this? I said, these are not directly associated with plate tectonics. But, what we know from our geophysics when we have these subductions some of these steeply dipping plates actually will go down to the core mantle boundary. You've got a big temperature differential across this boundary here. So, if you push something down there, something's going to come up. And that's when you get this buoyant body of mantle material that's been heated by the core and all of the sudden it starts to rise. It reaches a critical mass. It gets a kick from the subducting plate and it starts to rise up. Now, rocks are great because they hold on to their heat. They‐‐ they take a long time to heat up. They take a long time to cool down. So, once it comes up it holds on to that heat, but it's going up to lower and lower pressures. So, when you do that you start to melt it. And if you take something of temperature down here and you put it up here you generate an awful lot of melt, which will then give you your super volcanoes and Large Igneous Provinces. 21
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So again, accumulation of subducted material within the interior of the earth can actually promote these hot spots and generate these flood basalts or super volcanoes that come up not as a line of volcanoes in terms of here we see the Cascade Arc and the Cascade Volcanoes that are very close by. But, as a point source that begin with a very catastrophic eruption of flood basalts and then they wind down to a persistent plume tail. 22
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And this has been modeled in the lab. And you see here that this is actually a photograph of an experiment using corn syrup. It's the same as mantle apparently. I don't believe it, but‐‐ but the density contrasts are such that you end up with this very‐‐ this is‐‐ this is what initiates the‐‐ the rise in material. You need a certain mass to actually get off from that plate boundary and come up and then you've got a feeder tail that trails along after it. And if you look‐‐ this is one of the earlier papers in 1989. It maps out the plume heads that come up and give you these flood basalts and then these little tails wagging along after it. There‐‐ there are a number of issues with that particular hypothesis.
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But what it does it allows it‐‐ us to make predictions that are testable. We should see uplift of the surrounding area before we get the large flood basalt eruption. There's a narrow conduit to the source. They break up continents, if you look at how the Atlantic unzipped. You have Large Igneous Provinces in North where we now have Iceland sitting. We go down to the center. We have the Central Atlantic magmatic province. And then you go south we have the Parana and Deccan Flood Basalts part of which you see in South America, part of which you see in Africa. And that seems to have unzipped the Atlantic. So, predictions can be made and everything is fine, we can explain it. 24
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However, and this is why geology's a great subject, there's always that however. One size does not fit all. And so, do we throw the baby out with the bath water? Well, let's‐‐ let's look at a couple of examples of what doesn't fit. Hawaii doesn't fit because you've got this long chain from zero all the way back to about 86 to 90 million years. We weren't allowed to drill major so we couldn't age date that one. A bit of a bugger, but never mind, but no flood basalt plume head material at the end of it. It's not on Kanchaka, which is right here. Seismics show that it's not been subducted beneath Kanchaka so it doesn't fit. We look at Ontong Java here. This is the world's largest Large Igneous Province. The biggest super volcano if you like in the world and the 1989 paper they were saying Louisville was the hotspot. You see here we have a subduction zone that's destroyed part of this, but the plate reconstructions mean that Louisville misses Ontong Java quite spectacularly. There is no plume tail associated with this plume head so there are problems with that. 25
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Other‐‐ other lines of volcanoes here‐‐ we look at Hawaii, there's an age progression. It gets older as you go away from the‐‐ the currently active volcano. In others in the Pacific you don't see that. There is no age progression. So, it appears to be breaking down.
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This has actually led some other people to suggest oh, you don't‐‐ plumes don't work. You need too many variants, they don't work. So, everything's done from the upper mantle. We need nothing from down there. 27
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It just means that we have a very heterogeneous upper mantle. If we have‐‐ for example, I said the Atlantic opened because of the effect of plumes that forced the continents apart. In this hypothesis it's the opening up of the Atlantic will reduce pressure and then cause a lot of melting of the upper mantle and you generate the super volcanoes that way. Now again, this one ends up with testable hypotheses, but a lot of variants. Neither one works for every case out there. And that's the intriguing thing. We have these observations‐‐ lot of magma coming out in a short period of time and we don't know why. We don't know how to predict them. We don't know what environmental effect they could have and that's what I want to start looking at.
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And we'll start off small and we'll get bigger. Yea.
Audience member: [ Inaudible ]
Clive Neil: Plutonic LIPS. You‐‐ you actually do see some in the Caribbean where‐‐ where it's been tipped on its side. You can actually see some accumulate layers within that and that's on Aruba, great place for field work.
Audience member: [ Inaudible ]
Clive Neil: Well again, what you can‐‐ what you can do with the ones that are there you can actually calculate because you look at the composition of the magma at the surface. It's not a primary magma. It has been modified since it left the source. You can calculate, but if I melt the peridotite this is the composition I expect. This is what I see. The water's fallen out. And you can actually do a mass balance to say well I know that there's going to be this much cumulate material beneath it in order to generate that. And then in the seismics you start this oh yea, I can interpret that layer now as a cumulate layer. So, there‐‐ it's‐‐ it's a sort of a circular argument, but you can use the observables to actually track back to see what your‐‐ what your seismics are actually telling you. So, there‐‐ there are cumulate LIPS, they're all cumulates, because you have such a thickness there there's going to have to some accumulation that goes on. 29
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So, we start off looking at just these related to plate tectonic volcanic eruptions. 31
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This is Pompeii, A.D. 79, very famous. We have Vesuvius erupting. And what you see here the‐‐ are the preserved people and dogs from Pompeii because they got caught in a [Inaudible] daunt or a‐‐ an ash‐‐ an ash avalanche that came down the mountain. And they're preserved because their skin solidified the ash around them before it got burned away. This poor old dog was tied up and you can see caught in his death throat, just preserved that way. This‐‐ this chap apparently just gave up and then these were all found down by the docks. And when you actually look into them you can see that their skulls are all exploded because flash boiled the water in brain, bam, gone. So, it would have been quick, would have been quick. So, yea if you're going to go I suppose quick is good. 32
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It‐‐ this is from‐‐ from an explosive‐‐ this one was from an explosive volcano. This is in Hawaii, where we‐‐ we have very runny lava that comes out, but if you don't get out of the way your house gets burnt and the school bus gets inundated. I think everybody got out of that. 33
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In Gomma in West Africa, lava flows and no respect to‐‐ of infrastructure. This lava went right down the main street of Gomma, two meter thick lava flow went down and now you can see it's a bit of a problem getting around in Gomma. 34
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One of the big issues is ash fall. So, over I've got a‐‐ a little electro microscope image of ash fragments. They are very small, point 01, but look how sharp they are. When they come out and you start to breathe that in, it'll get in your lungs, but it won't come out. So, your body says foreign out‐‐ foreign body in here, got to get rid of it. So, they can't get rid of it, they isolate it. So, they‐‐ they actually put a film over that shard and if it's in your lungs that means that you cannot use that area of lung to exchange oxygen with your blood. And if you keep breathing it in, well, you just asphyxiate and you die of silicosis. In Pinatubo, it was falling roofs. The ash built up to such a thickness on structures that the roofs collapsed. And when that happened people died, which was not good. 35
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Mudflows‐ this ash gets remobilized. After Pinatubo they had a monsoon go through and that remobilized a lot of the ash into these mudflows and it's like liquid concrete. So, it can clog up rivers and completely change the drainage and it goes on for decades after the eruption because these are very unstable deposits. 36
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The other issue is how do‐‐ how do they go global? Well, they get into the upper atmosphere. So, I've got here‐‐ this is‐‐ this is altitude down here and this just shows you the pressure as‐‐ as you go up the air gets thinner and you can't breathe as much. If you get into the stratosphere you can get into the JetStream. Once you get into the JetStream you go global. So, this can actually transport volcanic emissions around the planet and depending on those emissions it'll either heat the planet up or cool it down. 37
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With Pinatubo we had NASA satellites up there that were tracking the upper atmosphere and it showed that Pinatubo put a lot of sulfur dioxide into the atmosphere, which reflects sunlight. So, in Northern Indiana we had two very pleasant summers, mid 70's, no humidity. It was great. Then the sulfur dioxide got taken out and we went back to 90 degrees and humidity and mosquitoes. But‐‐ but again, this shows you if we‐‐ if these erupt and get into the stratosphere they can go global and they can affect global climate.
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There are catastrophic eruptions. Tambora was just a small one, but we had an 1816 year without a summer in Europe. Actually snow in June was reported. And you can see here Tambora was a big eruption in terms of cubic kilometers, but in terms of what we're going to be talking about this is small. 39
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Krakatoa is another one that blew its top and this‐‐ this blew material halfway around the world. It was a big explosion because sea water got into the magma chamber, flashed to steam and just blew the top of the volcano off. 40
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Again, this‐‐ this was impressive because the explosion was heard 5000 miles away. Number one, it left a hole 6 kilometers wide and 80 cubic kilometers of the material was actually gone, just blown to smithereens. 41
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And they actually found material, tropical vegetation in African deserts from that eruption, caused a tidal wave 120 feet high, that killed 36,000 people. So, it's not just the eruption, it's the tidal wave that can then‐‐ then follow. 42
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So, those are small ones. Those cause local extinctions. We're talking about mass extinctions. How do we go global on a much bigger scale? And this is where the super volcano idea comes in of going global and causing these mass extinctions. Now, right now we have two competing theories for causes of mass extinctions. One is the very sexy meteoroid impact. Extra‐terrestrial is going to come in and kill everybody. It killed all the dinosaurs or did it? And then we have super volcanoes. Volcanic eruptions that go global and perturb the climate in such a rapid rate that life cannot evolve to keep up with it. 43
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So, if we look at the geologic record and just‐‐ this is just to show the different divisions of geologic time. The‐‐ the point being there've been five possibly six major mass extinctions throughout geologic time. And there's debate as to whether we're in the sixth one right now. That there's‐‐ the species are going extinct at an alarming rate present day and this could be another mass extinction. 44
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But, if we look at the geologic record we need to look‐‐ we look when life was first abundant in macrofossils at about 570 million. But, the‐‐ the most catastrophic one that we know of was about 255 million years ago where 80 percent of species went extinct. The question is why? After they found the Chicxulub impact crater for the K‐T boundary, the dinosaur extinction, everybody's been looking for this one. And they found one in the‐‐
Northwest Australia off the coast of Northwestern Australia. It's not very big. It's smaller than Chicxulub. 45
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But, if we then look at this table here, these are the numbers. These show you mass extinction in the general scale, but every time there's been a mass extinction there's been a Large Igneous Province or super volcano forming and erupting and going off. If you look down at this one, we're 80 percent what extinct; 255 million years ago there were 2 Large Igneous Provinces erupting, one in Siberia and one in Southwest China [Inaudible]. Exactly the right age and again we go back, we've got the Central Atlantic Magmatic Province, we've got Karoo/Ferrar here, this one. It goes on and on and we can actually start to correlate the ages of these Large Igneous Provinces with the mass extinction. And that's been the‐‐ the intriguing thing of the‐‐ what‐‐ how‐‐ how does this cause a mass extinction? We say, well they go global. They get their material up into the upper atmosphere, but we need to actually make sure we understand how that works. 46
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So again, here we look at the end of the dinosaurs because we've got this very sexy impact crater in Yucatan Peninsula. It's a big impact. It put material into the stratosphere. Actually material probably left earth when this‐‐ when this impact occurred. But, before the impact we had Deccan Traps going off in India severely stressing the global environment. And if you look at the geologic record there's‐‐ there are lots‐‐ lots of the macrofossils are in decline leading up to the K‐T boundary, up to this impact. It was pushed over the edge by the Chicxulub impact. So, the two of them combined tended to make it quite spectacular and then all these big boys died off. 47
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So, you can see here this is now a gravity map of the Yucatan Peninsula and you can see the sort of bull's‐eye pattern coming out. And the Integrated Ocean Drilling Program announced just before Christmas that they have approved a drilling expedition to the Yucatan and it's going to be a combined offshore ocean drilling and onshore international continental drilling program to drill this ring structure to actually recover the impacted material and the impact melt to get an idea of what it‐‐ the exact scale of these‐‐ of this impact actually was. And that should be‐‐ should be 2014 when that‐‐ that occurs. 48
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But, there again there are other reasons why the dinosaurs may have gone extinct, maybe not breathing these gases, but maybe some volcanic gasses. But, it's always good to tell people to quit smoking. 49
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So, let's talk about the environmental impacts of super volcanoes as we understand it. And I preface that because we are dealing with something that is not really occurring present day. So, we have to look at the geologic record and make inferences on the basis of what we do know. So, this is just a flow diagram, you won't be able to‐‐ to read it I'm sure, but I've put it in here to show that the assumption is that when you have a Large Igneous Province, you have a large release of carbon dioxide. That may not be the case. But, if you do it can lead to global warming and it can lead to ocean acidification. It can lead to a lot of die off. It can lead to increased weathering and these red boxes represent areas of doubt, where we don't have much evidence to support it. It is something that is a logical inference, but it is not conclusive. 50
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So, the thing to do is to go look at the rocks. That's where all the information is. So, we've got this spectacular view of the Deccan Traps out there. And you see here we're now down‐
‐ so we've gone from the field regional area to a microscopic slide. This is about 2 mm across. This is a little olivine crystal and that's a little melt inclusion. Now, when you get these melt inclusions in the crystals, they're a little tape recorder, because that has preserved that melt composition prior to‐‐ as it was prior to eruption. When you bring it up all the gases that were dissolved in the melt tend to resolve out because it's the pressure that keeps them dissolved. So, the material around it is useless for understanding. Well what was the carrying capacity of that magma, because it's all gone? It's gone into the atmosphere. So, we look at these inclusions and here we see one in olivine and over here, we've got another right there and we can see them down here. We know there's a lot of glass because the one's outside the glass, the ones outside the crystal had a lot of bubbles in it. So there must have been a lot of gas coming out. So, these inclusions can tell us exactly what the compositions were and what the abundances were of the elements that give us the gases that are then emitted into the atmosphere. 51
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And the guy, these‐‐ is Steve Selvin and his co‐authors have put together this model and this actually for the Columbia River Basalt, which were the parents to Yellowstone. This was the first eruption of the Yellowstone hotspot was the Columbia River. And there was an awful lot of SO2 that went into the atmosphere from Columbia River; not CO2 but SO2. SO2 gives you global cooling, CO2 gives you global warming. 52
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Now, what we've also got to remember is that when we bring magma up from the mantle it's going to pass through the crust and other sediments that are there and some of these sediments could be these methane hydrates. These form in oceans on continental shelves where you have deep water where there's a lot of pressure. It's quite cold and basically you end up with methane ice. You get ice crystallizing within the sediment that contains an awful lot of methane. If you either reduce the pressure by lowering the sea level or you heat it up all that methane evaporates, goes into the atmosphere and methane is a much more intense greenhouse gas than CO2. We know, for example, in Siberia where we had that big volcano at the Permian‐Triassic Extinction. They've erupted through vaporizing coal measures. And you can see here you got a person for scale. It's always good to carry a person with you when you're dealing‐‐ taking geological photos and you can see how thick some of these coal beds can be. That's a lot of tracked carbon that gets immediately released back into the atmosphere. So, there's‐‐ there's‐‐ not only do we have to worry about the gases within the lava, but it's what does that lava interact with that could actually compound the environmental impact?
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So if we go to the oceans, we're going back to the LIP map again, you can see over here in the Western Pacific we have a lot of oceanic flood basalts. We have Ontong Java. We have Manihiki, Hikurangi and Shatsky; these are the big ones. Over here we've got the Caribbean. Some are emergent, but most are formed under water. 54
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If we look at the biggest one, Ontong Java Plateau again here this is‐‐ the map is the area. But this is the same scale Ontong Java is the same size as Western Europe and it's a volcanic construct that formed 122 million years plus or minus 3 million years, which is geologically pretty damn quick. 55
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However, there's more. If you look at what's been done by the German group, led by Ky
Hernley [Assumed spelling] they have actually now gotten data from the Hikurangi Plateau and Manihiki; they are exactly the same age. They have lavas of exactly the same composition. So, this Western Europe size is now Europe size. And they're going to form very, very quickly. So, you're going to form Europe pretty much instantaneously by volcanism. That is going to perturb the environment. 56
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And what we see here is a schematic that shows that you're going to have sea level rise. You're going to have a lot of gases emitted into the ocean; a lot of material is going to be dissolved into the ocean. Your going to change ocean chemistry. You're going to promote initially a bloom, a lot of productivity and then there's going to be a die off as the CO2 gets into the upper atmosphere. It starts to dissolve into the water and you start to acidify the oceans. When you acidify the ocean, life dissolves and dies. 57
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And we can actually see that punctuated throughout the geologic record by this very organic rich layers, shales that typify oceanic anoxic events. And over here, I just want you to look at the purple and I want you to look at the red. These purple line bars here represent oceanic anoxic events. These red bars here represent Large Igneous Provinces or super volcanoes that were going off. And they seem to punctuate‐‐ these oceanic anoxic events occur when you have Large Igneous Provinces forming in the ocean. They‐‐ they dramatically affect global ocean chemistry that promotes both growth and then a lot of death in the oceans. So, the one thing I want to point out, the major problem in our understanding of these environmental effects is the fidelity of the age days. We see here that we plus or minus 3 million years is a long time. Did they all come out within 50 thousand years or was it basically oozing out continuously at a constant rate for over 6 million years? We don't know. Our age dating techniques don't allow that. Obviously the more rapid the eruption rate, the more dramatic the environmental impact is going to be. And again, this represents another area of research that we've really got to get tied down to understand when were these eruption events. Did the Ontong Java form in one event? Did it form in several series of smaller events over that age range that we can just to get to with our current age date techniques? We don't know. So, there are still questions. 58
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But again, this die off is seen globally. Oceanic anoxic events don't just occur in one little region. They're global events. You can correlate them around the world in oceanic sediments either through drill cores from the oceans or where oceanic sediment is now on land. You can see here, this is some drill core from Shatsky Rise, the sediment above it. And they've actually recovered the oceanic anoxic event one, which correlates with Ontong Java plateau forming. 59
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Other‐‐ other indications of‐‐ of issues are in this little ratio. Here's looking at strontian in ocean sea water. So, the only thing you've got to remember here the arrow going down this way means a lot of mantle input or volcanism and you can see here we're now looking at how ocean chemistry has changed over time 200 million years to present. And these red bars represent major oceanic anoxic events. 60
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So, you see here we start to see a decline in this ratio around the time the Central Atlantic Magmatic Province was formed. 61
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We then have a recovery. We have an oceanic anoxic event recovery. Then we have the Karoo event and we get another decline. 62
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We have the East Indian Ocean starting to open. 63
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We have Ontong Java Plateau, a major drop off and an oceanic anoxic event. 64
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We have the Caribbean plateau in a little belt from the Ontong Java, another drop and another oceanic anoxic event. 65
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KT Boundary and Deccan Traps and also the North Atlantic eruption events caused a perturbation here. 66
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And a little change when we had Columbia River forming back‐‐ back only about 15 to 16 million years ago. 67
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However, nature is great. We have other events that have no effect on the ocean. But, these events appear to be all subarial, erupted above the ocean. The other ones were all beneath the oceans, within the oceans. So, we can see here that okay, we've got these things‐‐ they don't really coincide with what we would expect with input from volcanism. 68
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So, what about super volcanoes today? I've‐‐ there's four circles here and these represent the currently active ones. Hawaii is an incredible volcano and continues to erupt, quite spectacularly when you're in the locality. But because the magma is very runny, you don't see the explosions. You don't see the stratospheric emissions as you would see in some of these others. Now, Iceland similar sort of thing, you get sea water into the magma chamber, it could really mess up air travel in Europe. I mean I got caught in 2010 trying to get back from Vienna and we get to Frankfurt to get on the flight to Chicago. We get on and we wait and we wait and they come on‐‐ the captain comes on and says, "Our trip is going to be three hours longer than normal." Okay, well we had to fly due north, straight up the North Sea then go around that volcano that was erupting in Iceland and then come down and into Chicago that way, because the ash cloud would have put a bit of a crimp in the engines. And you really want the engines to continue working when you're at 36,000 feet. There's the story of the British Airways jumbo that flew through a plume of volcanic ash over Indonesia on its way to Australia. You're at 36,000 feet and all four engines stop. Jumbos do not glide, the plummet and the only way you can get the engines to work again is to open them all up, put it into a forced plummet, put the air through the engines to blow the ash out and then got all four engines started around 18,000 feet. I'd say there were a few changes of underwear required in‐‐ in the passenger cabin there and probably in the cockpit too. Ethiopia, we're going to come back to Ethiopia. I'm going to leave you with that one at the end of the lecture.
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But let's have a look at the‐‐ anybody want to pronounce that for me? It's‐‐ it's not English but it's Icelandic and its Eyjafjallajokull [Speaking Icelandic] there we go. 70
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I put this up here to show you the spectacular eruptions that you see.
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And it is a spectator sport, but watch what's coming out of here. There's a lot of blocks being blown out, there we go. 72
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Hello. There's people standing there.
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Must be a‐‐ must be geologists trying to get some fresh samples, you know. 74
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Yea, get your baseball mitt on. 75
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[Inaudible] 76
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[Inaudible] 77
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But you can see here the types of explosions that are going on.
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And this ash cloud a lot of its coming down.
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But a lot of it is going up.
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And again, you can see them coming down. Now they've figured out we've had enough. 81
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But look how high that is getting. 82
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And this was‐‐ this was all over Europe. 83
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It really shut down air travel
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Because you really just can't fly planes through that sort of ash. 85
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So what about Yellowstone? Now, here was an interesting thing. We've got a very runny magma in Iceland that caused the regional crimp in travel. But in Yellowstone, we have something a little spectacular. We have this very runny magma coming up and it can't get through. So, it's pounding under the continental crust and it's actually melting that continental crust and its changing its composition. One that makes from a very runny magma to a very sticky magma and when you have a sticky magma and a lot of gas, gas can't escape. When it does, it explodes in a big way. 87
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So, this is an aerial view or satellite view of Yellowstone National Park. You can see here this is actually the whole kit and caboodle. This is the plume tail. This is the plume head, Columbia River Basalt's right here and then it's‐‐the plume tail is wagged a little bit through the Snake River Plain and then we get into Wyoming where the current‐‐ the current Yellowstone National Park is and this is in Kansas. This is an ash deposit in Kansas from a Yellowstone eruption. This little map down here I put up to show two things. This is the extent of ash deposits from various Yellowstone eruptions. This is the 2.2 million year event. You can see it covers half the USA. This is the 600,000 million year event and then we've got the 1.3 million year. This was Mount Saint Helen's in comparison. Mount Saint Helen's was a little‐‐ a little pimple compared to what we see a being deposited from Yellowstone. 88
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So here, this just emphasizes the fact that we have this‐‐ this very runny magma that comes up. It starts to melt. The continental crust becomes much stickier, much more silica rich and sticky. It gains more gases from assimilating these‐‐ these crustal materials, which makes it more explosive and then more gas goes into the particular‐‐ the environment. 89
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So, again here I'm showing Mount Saint Helen's for scale and what I want to show is some video from the Mount Saint Helen's eruption just to show you these types of devastation that occurred there. In the class this morning I got depressed because nobody in that class was born when Mount Saint Helen's went off. It's really depressing.
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[Video] Ash covered trees go by the lateral glass from the May 18, 1980 eruption of Mount Saint Helen's provides stark evidence of the danger of Cascade Volcanoes. Trees, ash and water from mountain glaciers turn swollen rivers into raging torrents and destroy everything in their path. Only the lower half of the once beautifully symmetrical mountain remains together with the lava dome that formed inside the excavated crater. Remnants of the former lush landscape are now surrounded by thick layers of gray volcanic ash.
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Clive Neil: So, this one is time lapsed photography of the actual eruption. 96
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And it was very uncharacteristic. It was a lateral blast that nobody expected. Everybody expected it to be vertical and the lateral blast actually killed a U.S. geologist stationed a few miles down here because once it went, there's no way you can outrun it. That's your luck. So he is now fossilized beneath that pile of ash. But something that is just amazing is to think of the types of forces that go‐‐ you basically blew the top off‐‐ the side off that volcano. A lot of force involved. This was very small. 97
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If we look at the volumes of material, this was the biggest Yellowstone eruption that we know of, a 2 million year ago eruption. This is Mount Saint Helen's by comparison. You can see there's a big difference so that 12 million year event came from the hotspot when it was there in Idaho still. But, sorry the 2 million year one comes from the current Yellowstone event. But as we track back we can still find deposits of ash and a lot of violent eruptions that occurred over geologic time. 98
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So this is in Nebraska. This is an ash deposit in Nebraska and they've actually found a huge kill of prehistoric rhinos, prehistoric horses and dogs that all succumbed to this particular ash fall deposit. And what they found was is that smaller animals died quicker because their lungs got choked. They all got‐‐ breathed in the ash. The larger ones took a lot longer to die because they were all together in a watering hole and that's where they ended up paying the price.
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[Video] And the feature of ash fall is prehistoric animal skeletons are very thin. This was something that happened almost 12 million years ago. Birds [Inaudible] rhinoceroses, camels, bisons met their death in a water hole and their skeletons are just perfectly preserved now for 12 million years. And that's the whole‐‐ [Inaudible] is to give the public a first‐hand view of a real paleontology site, which is still actively being excavated.
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Clive Neil: Okay so that's in Nebraska and that's Yellowstone or‐‐ a prior Yellowstone eruption. Same hotspot, big eruption and you're talking about ash deposits that some of the early ones did cover the country and you can see it in the geological record and then you can see what it could do to life that was around that time. 106
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So right now USGS is actually monitoring Yellowstone closely because we have‐‐ the surface is moving. It's tilting in the direction of the arrow and you can see that with the light levels. The light levels are changing and drowning the southern portions and the northern portions are actually becoming elevated. Well, that tells you stuff is moving underneath the national park. 107
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And here is‐‐ these are the earthquakes that have occurred there since 1973, but again there's a lot of earthquakes occurring between Yellowstone because of magma movement. It's not on a plate boundary there. All of these earthquakes come from magma that is moving beneath the surface. The very fact that we have tilting indicates that we have a very dynamic situation beneath Yellowstone. 108
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It's not just the hot water springs that tend to burst forth quite regularly. There's magma down there too, hence the heat. So, this is projected. We've got all the states here. This is Yellowstone. If‐‐ if Yellowstone erupted tomorrow there's a 100 mile diameter here where there's total destruction, gone. And then this is‐‐ massive devastation is the way it's been called in this particular 500 mile area here. And I think we're just okay, aren't we? So, again when will it go off? We don't know? All we know is it's still very active. And you can see that there. When it will go off, we have no idea. 109
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So, just to bring it to a close then what I've circled here in black the Large Igneous Provinces that scientific ocean drilling has actually drilled into and we have samples of. I've circled this one because the International Continental Drilling Program has just completed the Snake River Plain drilling, which is part of the Columbia River‐Yellowstone igneous project. So it's pretty fundamental in increasing our understanding because if we look at the oceanic LIPS, they have not been contaminated by continental crust. They tell us a lot more about the compositions of where that magma came from and how‐‐ how it evolved in the oceans. Nope. Don't want to put that one up. 110
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So, I've circled this one here, which is Ethiopia, the Afar region in Ethiopia, spectacular volcanic area that was very difficult to get to because of the old Civil War that's going on. 111
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But, if we look at Ethiopia, this is the Gulf of Aden. This is the Red Sea. What we see is we do see uplift occurring and what is happening is this is splitting apart as is this and East African rift is‐‐ is a failed rift because we have a rising body underneath the Afar region. We've just seen eruptions of a surfacing super volcano in Ethiopia. The question is, is when will the big flood eruptions start to occur? We don't know. We have no idea. But what we know is the observations are that they are splitting apart the Middle East from Africa. I mean if we had waited a few million years, we wouldn't have had to build the Suez Canal. We would have let nature do it for us. Again here this being split apart and here they're starting to pull apart, but of course doing field work in this area was thought with other hazards such as guns and wars and kidnappings and beheadings, that sort of thing. So, it's very difficult to get infrastructure in there such as seismometers to monitor earthquake activity and to actually monitor gas emission activity from some of the active volcanoes that are there. 112
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So, again ocean drilling has greatly enhanced our understanding of these Large Igneous Provinces that go along with super volcanoes, especially this is a new area really. The environmental impact of these things is now really starting to come into focus. 113
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Again, I already mentioned this with regards to the contamination. It's easier to get to the ones on continents. You don't have to have big drill ships and spend millions of dollars, but you have the added problem of contamination of the magma by continental crust. 114
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But, as I said there's these questions that still remain, not the least of which is predicting eruptions of any volcano let alone one of the big ones. 115
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There are no flood basalt from the present day; some would argue with that. There are no‐‐
Afar is in the early stages. Iceland represents the waning stages of a‐‐ a Large Igneous Province and Yellowstone is the plume tail. It is not the flood basalt stage. So, we are really trying to use the geology to look at processes that we can't‐‐ don't have any present day reference for. Afar may be it if we wait long enough and it erupts and we can actually see how flood basalts could work. 116
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And again, Afar is this sleeping giant. 117
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And again it comes down to the ocean drilling program. This is a much younger me in late 1992 when I didn't have gray hair and I had no gut. I need to do more field work. But, the rocks that we pulled up from Ontong Java added another piece to the puzzle because it showed that these were erupted well below sea level in all but one site. We did not expect‐
‐ a lot of unexpecteds there, but they add to the understanding of these sleeping giants and thank you very much.
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[ Applause ]
Clive Neil: Any questions? Good we can all go to the pub.
Audience member: [ Inaudible ]
Clive Neil: Well, I mean there's‐‐ let me answer that obliquely to begin with. Hopefully it will all come into focus. One of the physical volcanology and understanding how you can actually get these flood basalts to‐‐ to run thousands of kilometers, I want to put back up a picture of the Ontong Java because the fact is we know that they do. We've got to have a very effusive source to actually feed the lava flow. That lava flow then has to be encased to keep the magma running. So, that lava flow has to‐‐ the effusive source has to be there for a long time in order to have it run over hundreds of kilometers, alright. The question I have is on land, it's pretty easy. We know that we have lavas of the same age at exactly the same composition on the later at 1183 and at 807; that is 1200 kilometers. How do you do that under water? Similar process, but what it means is that that lava‐‐ that the eruption rate has to be much, much bigger than what we're used to and what we see present day. And it's a big‐‐ big question in physical volcanology. Again, Steve Selvin has done a lot of field work in the Columbia River to actually answer that question. How do you get these very long lava flows? And a lot of it has to do with inflation. So, you start off pretty small and you keep pumping magma in the middle and you inflate it and then that forces the tow out to go further. You inflate it again, inflate it again, inflate again.
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So, there's‐‐ there's‐‐ you have to have that continual supply of magma at rates which are pretty much unprecedented today. So that's‐‐ that's a big issue because we were just amazed when we drilled here and did field work down here and compared it with what was from site 807 exactly the same, and it's 1200 kilometers away. Something that's the size of Western Europe you find exactly the same magmas here, here, here, here, here, here, exactly the same. Yea Terry.
Audience member: [ Inaudible ]
Clive Neil: It's the entire ocean. You actually‐‐ you actually—
Audience member: [ Inaudible ]
Clive Neil: It‐‐ it maybe, as I say we find‐‐ let me rephrase my answer. We find these black shale horizons throughout the world and then you can see in where is it, this one here. 120
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You normally find them with‐‐ with very‐‐ in limestones, especially in the cretaceous. You‐‐
and they stand out like a sore thumb and in some of the type‐‐ localities in Italy are beautiful. You can go see them there. In regards to continental shelf regime I'm‐‐ I know that there are some localities that do show that anoxic event. You do not see the black shale as well developed. But what you do see is an increase in organic carbon in the deposit of that horizon. So, you may not see this very vivid and easily the spotted black shale horizon there, but you do see it geochemically. And that's why it's amazing. It's global and it's in the oceans. Yea.
Audience member: [ Inaudible ]
Clive Neil: It's not magma. It's not magma. When it comes up it's actually rising hot rock and then it creates, it hit the rigid lithosphere. You know it's supposed to push it up a little bit. You get uplift but when it can't do that, you've still got material coming up and it starts to spread it that way. It spreads it out in three ways and you end up with a three‐pronged rift such as you see in Ethiopia right now. And the East African rift is the failed portion of that, that rift. So, it's‐‐ it comes up and it's‐‐ it‐‐ think of it as when you've got convection in the mantle and it’s not molten magma that's doing it, it's plastic rock. So, when you have this hotspot that comes in the plume head, it doesn't melt until it gets to the lithosphere and stops. And then it starts to melt‐‐ it starts to melt as it's spreading out and it falls apart and rifts the continental‐‐ or rifts the oceanic crust so you end up with a conduit to get material to the surface. So it's‐‐
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it's not molten until it’s close to the lithosphere. Then it starts‐‐ you get a 30 percent melt that goes on, which is huge partial melt, but you've still got 70 percent of plastic material there that can rift that thing apart. That's‐‐ some of these experiments they do with corn syrup. It's the density differences is what they're after and not the actual materials. So, that's Ian Campbell's work at the Australian National University has looked at that and is‐‐
there's a group at the University of Rhode Island doing very similar sorts of study. So, yea.
Audience member: [ Inaudible ]
Clive Neil: Well, obviously it's going to stay above its liquidous temperature otherwise it will stop flowing and it comes down to the fact of the rate of coming out of the conduit. So, the temperatures that have been‐‐ been calculated, there's a delta calculated in delta versus the ambient mantle and its 300 to 400 degrees hotter than the ambient mantle. And that is a huge Delta T at that point and then it causes the degree of partial melting. So, you have a large degree of partial melting up to 30 percent of that material, which means you have a lot of magma to get out, which then allows these magmas to follow a long way, because you're feeding that flow and keeping the magma you've put out warm so that it can be plastically formed and inflated and then you keep pushing it out and pushing it out and pushing it out. It's‐‐ if you get a chance or if you have been to the Columbia River, you see the thickness of some of these flows. I mean, it's pretty impressive, especially in the rows of
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formation. [Inaudible comment] Right. Actually no it would be‐‐ be higher than that. It's close to 1500 degrees. Yea, yea real degrees not Fahrenheit; we kick ourself and keep all units. I can't believe that. Yea Todd.
Audience member: Is there a gold usually associated with these rifts?
Clive Neil: Interesting. Interesting. It depends on the hydrothermal circulation that gets set up. We found no evidence of mineralization in Ontong Java but we did in [Inaudible] and the question is well why? Well, [Inaudible] has a continental signature associated with it because it forms during the rifting apart of Antartica or Australia or India. That is‐‐ that is we actually found and I related to you that we found continental crusted materials in the middle of the Indian Ocean when we were drilling in one site. We've gone through these typical basalt lava flows and then we hit this conglomerate had Gneiss' in it and those Gneiss' are very similar to the ones in East India. Present day they are now exposed. So, it was close to continental material that had all goodies to set up with the‐‐ with the hydrothermal circulations that come with some of these‐‐ these heat engines you get with a large [Inaudible] but those ones that form‐‐ just in an oceanic base in Ontong Java. We saw nothing in Solomon's and we've seen nothing in the drill core to suggest that there's any mineralization going on. So, you see it with Siberia because you have a huge sulfide deposit because it was erupted through vaporize. So, you have a lot of sulfur being dissolved into the magma then the sulfa became and when you have that happening it takes all the [Inaudible]
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sulfur loving elements with it such as platinum, gold, sea copper and so you end up with this huge economic. Not because that was the magma composition, but what it erupted through changed the composition and changed the partitioning of the elements in there to actually form into sulfides. And that was on continental crust, not the‐‐ not in the oceanic realm. Yea.
Audience member: [ Inaudible ]
Clive Neil: Ah yes. I don't know about major. There was an extinction event. 124
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Here we had the mid [Inaudible] event about six percent when extinct. It was also the same time that the Ries Crater formed in Germany, which is a small one. If you go to Ries, all of the houses are built out of the impact. It's pretty neat. Go start hitting people's houses with a hammer they get quite annoyed. So, but yea there was a six percent decline at that time. Not my work, somebody else's work. I don't look at extinction events like that, calculate. I try and correlate them with what could cause it. Yea.
Audience member: [ Inaudible ]
Clive Neil: No, I mean a super volcano means well what were the eruptions like. They have to be big eruptions. What‐‐ in looking at what people term super volcano, over 90 percent of them are associated with Large Igneous Provinces. Lassen, Yea, it's big.
Audience member: [ Inaudible ]
Clive Neil: Right. Right, but there again you look at the products that came out of that. It's what‐‐ how widespread were they? How often did they erupt? Was there associations with any regional die offs such as we saw in Nebraska and the ash falls from there and Yellowstone. So, it could be. They're not restricted to Large Igneous Provinces; most of them are, but not all of them. Yea.
Audience member: Is there a super volcano in Hawaii?
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Clive Neil: In terms of material erupted, yes. In terms of environmental impact, no, Kilauea. Yea. Yea.
Audience member: You mentioned how there's two deposits like with a hard flow are they the same material of each other. Are they the same magma?
Clive Neil: It was a lava flow, yea, yea, yea.
Audience member: So you get two of the same compositions of magma miles away from each other?
Clive Neil: Exactly.
Audience member: Do you have your own theory about that though? Do you have any idea?
Clive Neil: Oh, I have a pet theory. I mean again, I think you've got to have‐‐ you're dealing with an area of‐‐ a real of physical volcanology that we've not delved into. How do you transport lava under water hundreds of kilometers, over 1000 kilometers? So, you've got to have either a fissure eruption or you have a point source that is effusing magma. If you put it right in the middle let's go 600 kilometers each way. But we can't find anything in the middle that looks like its event. So, yea
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how do you do that? I don't know. I really don't know. It is one of the‐‐ that's why we have to do research and go back to the Ontong Java and go moldy again. So, maybe somebody younger and bits might drop off this time and we don't want that to happen. Yea.
Audience member: You mentioned when the [Inaudible] impacts the lithosphere you get an uplift and a possible lifting of the [Inaudible] Do you see that in any of the other igneous provinces?
Clive Neil: I'll go back to my favorite, Ontong Java. It's the biggest that we know of. It all forms‐‐ well until Lat 192 it all formed well below sea level. The amount of uplifting that was expected was much less and that's what started people to say, "Well plumes really can't cause this." 127
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Then we went to, let's see where is it? We went here, site 1184 and this classic we got a bunch of igneous petrologists and a bunch of sedimentologists on board and we bring up volcanic plastic sediment and we bring up about a kilometer of it and it was, I don't know a kilometer, about 200 meters, 300 meters with 90 to 100 percent recovery. And this stuff has to‐‐ it comes up on board and you have to describe it. Well, I'm an igneous petrologist. I look to that and I say, "That's sediment. I'm not touching that. Bye, I'll see ya later." So the sedimentologist comes up, they're igneous bits, we're not touching that. [Laughter] So we drew straws and the igneous boys lost or won, depending on your viewpoint. So, we had to describe it. What it helped us do was we found within the sediment as you went down fresh glass, 122 million year old fresh volcanic glass. Because it had been buried so quickly it was preserved. And I came on shift one night and I'm bleary‐eyed at midnight. I did the midnight to noon shift when I was on board. I came on and said, "Oh, what do we get. Oh God, more bloody volcanic plastic crap again to look at? What the hell is that?" You know you see something there that shouldn't be there. What's the first thing you do? You poke it. What is that? It was carbonized wood and we found carbonized wood several horizons throughout these volcanic plastic sediments. We had the first evidence of emergence of Ontong Java. So, what people have been saying for years is because this is the bathometric eye of the pelatuk. So we assume that's where you should find subaerial basalts or close to the surface. It's over here. 128
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So, if we then look at the reconstructions of these three, over here is right in the middle of it. Here we were just looking at one part of the puzzle. We weren't thinking about these two being attached and have since drifted off. So, we did find evidence of emergence in site 1184 and all that whining and moaning that went on about its sediment, I'm not describing that. Those volcanic bits in there were pretty cool I have to admit. And even some of the textures with sediments were pretty cool. And since that time I'm a reformed character because I think the way we can get to actually pinpointing eruptions and when they occur is to go and not core these edifices right here but to go out into the surrounding basins and get sediments that would deposit at exactly the same time. Then what we can do is we can go down and we do very detailed geochemistry. We can find inputs from igneous material. You can find the details in the geochemistry to say, "Oh, oh there's a big influx right there." And it's over about that and you can use microfossils and you can get a paleontologic age and you can get an idea of sedimentation rate then you get an idea of how quickly some of these pulses actually occurred. So, my next proposal to the ocean drilling program is to go drill the syn‐LIP sediments so we can get an idea of eruption and eruption duration. And we're going to try that with Deccan Traps because they actually have cause in [Inaudible] Japan from the Indian Ocean that preserve the syn‐Deccan sediment. So, that's the plan.
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