 Okay, thanks very much. So the the next course talk is by Fedra Abton. She comes all the way from New Zealand. So please stay here and listen Don't go away So Fedra, so Fedra is going to talk about really important subject here About all the workshop copying geodynamics and surface processes. So please go Thank you. I didn't think about the microphone situation when I chose my dress So I hope this will work. Um, I'm really excited about this workshop. It's kind of as Mark said been in the Planning for about four years. Um, so it's great that it's happening now Um, and you know, it sort of came from CSDMS and Jaisiewiczki being open to the idea of a Geodynamic focus research group and then CIG being willing to Join with this meeting. So it's great. Um, so we're gonna change tech. Is there feedback? I'm getting feedback. Okay. Um, yeah, so we're going to change tectonic regimes and and scale. So my Natural laboratory has been the southern Alps of New Zealand for all my time as a geologist gear dynamic system Now moving into surface processes. So and it's and I'm going to be talking about the collisional Collisional setting within southern Alps. I just like to acknowledge my co-authors Peter Coons who has also spent years looking at Active tectonic belts and southern Alps Sam Roy who's who's here, and he'll take any tricky questions on his models and Nick Richmond who's also at the University of Maine. He's a master's student. So as I Ambitiously said, I'm going to look at the coupling between geodynamics and surface processes and we're going to zoom in from the last talk I'm really going to look at the rocks because the rocks are what acted upon both by the tectonics and the surface processes So I said I'm going to largely going to focus on collisional settings and these are settings with high uplift rates high Eximation rates So we're we're looking initially at a largely supply limited system the rocks at the surface It's not covered by soil I'm not really going to focus today on sedimentation sediments but sediments obviously extremely important That's one thing that came up on our breakout group the role that sediments and the sedimentary record have And in telling us what has happened in the past So this is South Island of New Zealand and you can see this beautiful landscape and there's two this the Rock has two really strong planes of weakness one's a foliation and one's a jointing surface It's kind of really perpendicular to it You see both of them really reflected in the landscape that's that's produced right there But also it turns out makes it quite difficult to get from that bridge down to this lake and This is a It's a landslide dam lake and if we zoom out we see that that that feature to is a direct Product of the of the rock properties It's the the foliation surface is the sliding surface on which that landslide that landslide formed and dammed the lake so what I'm going to do today is talk about materials earth materials and process and I'm going to give a brief introduction and then talk about modeling Modeling the materials and the processes are trying to bring them together and then I'm going to Present a conceptual framework that Peter Coons and I and others have been working on for quite a while that where we're trying to really bring the jet dynamics and genomic processes that the Materials together with with the surface processes that are acting upon on those materials Okay, so as I said we're looking at dynamic landscapes And we want to look at the forces jet dynamics forces that are that are associated with deep earth processes I mean subduction Polition these are the large-scale forces that are driving these processes and then we have the the gemmophology the the shaping of the earth surface driven by atmospheric processes and Particularly in these dynamic environments that we're going to look at we end up with quite complex competing interactions and we get these dramatic Landscapes and we want to understand what what's driving those landscapes why they look like what they do What we can say about them So we're kind of coming at it from I'm really going to today I think I'm going to be talking about Materials material strengths and driving forces or stresses. So we have Instructive forces or or strength that keep the rock there versus destructive forces We have stresses things acting upon those those geological materials that That break the rock or and allow it to be available for a surface process to act upon it I'll probably use the word failure quite often and what I mean by failure is breaking the rock and failure can happen in a in a in a rock or a soil or anything and we can have Oh, I'm largely going to be talking about compressive forces But to get failure in a rock you have to break it So if you're pulling it apart you have to overcome that tensile strength of that rock if you've got a sand pile and for the sand to flow down to You have to overcome the frictional strength of that of that sand Or if it's a rock and you're sharing it you have to overcome a cohesive strength of that rock So I will use those terms or failure But what I mean is we we need in order for a to a road or transport a Rock or a part of a rock it has to break away from that the bedrock that it's connected to and that's kind of Really where we're coming from with this This conceptual framework that I'm going to present to you and also where we're trying to calculate What's holding that rock together? Why is it strong? Why isn't it strong and what's acting upon those rocks? Why are they breaking and failing? So I've just so this there's a variety with we've had most of these mentioned already today Obviously, there's that the topography and in a mountain landscape and topography can both Strengthen a low topographic load will strengthen that the material the rock mass But the steep slopes due to the high shear stresses can weaken so topography kind of acts as both a destructive and a constructive force We have the blue veal and glacial horses acting upon the landscape I Couldn't find a picture with everything I wanted and the glacial is kind of what missed it out, but so So the blue veal we're talking about I mean water running over a strong rock isn't going to do anything But it carries tools it carries sands gravels etc. So that and the stresses and if it's a weak rock if it's a shear zone I mean it really doesn't take much for that those students With that process to a road we have Tetonic horses so in the landscapes that I'm we're looking at here, you know the southern Alps. It's a collisional environment the rock is constantly These are the GPS vectors. So the rock is constantly under convergent and strike slip It's quite a bleak system and Then now and then it is hit by seismic waves which Yeah, obviously we had quite a large earthquake a year and a half go which has given us a lot of a lot to work on Um, this this landslide here in the landscape actually occurred following a 7.1 in 1929 so, you know, why did that particular bit of rock break under those stresses rather than another so I'm first going to Talk about materials and material properties and then move on to process So southern Alps all the West the West Coast of the South Island has long been thought it known But um, you know dramatic uplift high erosion. It's where the the critical wedge theory was I've talked about in our breakup group this morning You know the two-sided wedge This the southern Alps was kind of the basis for some of those models. And so if we look at the Central central South Island across kind of the classic cross section across the southern Alps This is rainfall this map. This is sediment yield. This is The this the central southern Alps, you know, we have moderate to steep slopes. We have Rapid uplift and exclamation on this western side We have quite a bit of rain at times You know the rainfall is five to ten meters a year the rocks are just Just along the West Coast and greywackies and the sediment yields are some of the highest around up, you know Greater than 2,000 tons per kilometer per year and it's yeah, we know what's happening There's high uplift rates the rocks not that strong. It's being eroded rapidly and we're getting this huge sediment rate We moved down to South-Westland here again the rainfall is at least as dramatic, but here we've got near vertical slopes It you know, if you look at that picture there, it looks like the ice left yesterday. That's your left 10 of 10,000 years ago and the difference of course is the geology that those rocks are granite's granite diorites And they're just too strong for fluvial Processes to really influence them and it takes ice it takes ice to erode those rocks and what we see here is the steepest slopes have The lowest erosion rates and it's because of the material properties Um, this is this This Publication is already mentioned today. So this is just another example on a slightly smaller scale that comes from Huntington and Cleppes the challenges and opportunities for research and technology tonics And of course one of their their big challenges is is the topic of our workshop Over the next couple of days and here they they point out that there's these three catchments Similar erosion rates, but very different reliefs and question is it climate? Is it rock strength? Is it process? In this case they say it's likely to be difference of material properties so We have made quite a bit of progress and in taking and looking at how material properties and material properties that are driven by tectonics Are reflected in the landscape and the next few slides. I'm going to talk about a largely Sam Roy's work. So What he did was modify child which is Lancelot evolution model, which is very well used and and so he modified it so that he could include the that rock strength for a variety of of Products of tectonics. So we went into the field and and measured That the cohesion of this is the bedrock Jointed greyworkie and it's been deformed into cataclysides and gouges gouges along in a series of fault zones and by looking at the properties of the rock in the field and using this hook brown hook brown criteria here could estimate the Cohesion of the different different materials and then using this relationship for the detachment we can relate a rotability to cohesion Based based on field observations The other the other thing that happens in in the process of weakening driven by tectonics is a reduction in the The fractures a change in the fraction space and therefore a reduction in the grain size of the products of of erosion and so that's also Sam also classified that so that it at a grain size, which is a function of the fracture Spacing and and was into the models as well So if we just look at a couple of the of these models This is this is a that's the This model is only is homogeneous with just the strong the strong rock This model has a damage zone down the middle of it Based on those field observations so that the core of that damage zone is Much much weaker and much much easy more easily eroded and Then this this model we're looking at a map view down onto these models So flow outlook let here. There's a simple uplift put on to the model And hopefully this will make them run. Okay, so we can see immediately as you'd expect that There's a much Large difference in the in the form of the landscape as a result of the change in rock properties here It's all equally erodible and we get this kind of dendritic type pattern Here we've got this much more erodible zone. So that erodes out more quickly and These that these hillsides respond and we can look at how the sinuosity of the system changes with this Change in material properties Increase in the rate of nit point migration when you've got that weak zone And we can look at sediment storage and in these models as well. So the colors now represent how long a sediment stays in the system Yes, here the erosion rates are slower the slopes are slopes stay quite Steep the sediment is produced and and moves out of the system. Yeah, because we get we erode that material out We get that we get this nice less steep Main valley through here and what that ends up with this the sediment particularly the core sediment that's coming off the hill slopes stay in the system and in the amount of time That the bedrock and in the weak zone is armored is actually significant and so This zone is more easily eroded but because of that These slopes reduce the sediment stay in there and it protects it until a big storm and I think believe this model did have Storms so then the big storm might come through wash it out and then you'll get more rapid erosion Um, that's it these we've we've also taken that model. So this has taken that model and coupled it to a Strain softening geodynamic model. So instead of imposing we're saying this is where the weak zones are and let's look at how the landscape responds to that We're taking a geodynamic model. This is a simple simple collisional zone orthogonal collision and also simple or graphic precipitation model on top to to feed the to feed the rain into the into the landscape model so in this case The geodynamic model produces gets a strength. I'll show you to one is got no no They both have strands of me. So this the geodynamic model we predict where the Vault zones where the strain localization is going to occur we take and where we have the fully coupled we take That those resultants cohesion values convert them in the landscape model to erode ability And so we can see how they they feed back between the two So the top one has Geodynamics and the landscape evolution, but it does not but it doesn't feed the erode ability back this This one has the erode ability So initially they look quite similar. We see the the streams forming downslope but as these Strains often zones Development here struck that softened the weaker the more readily erodible Let's see if I can play that again. And so once these start How many things to coordinate here Does what you want? Control it with this it doesn't so yeah, so these start similar, but you see we start to get these other Weaker zones. It's much easier to erode that so we start to focus the deformation in there And it but the the water still has to the river still have to head out eventually So they just pick a couple of these zones and and move through so We do have Quite a this is this is coupled but but there's there's still lots to do and one of the things that We want to do is Start to think more about breaking that rock so these are these are diffusional landscape so that the Erode ability and the erosion the landscape isn't a diffusional law, but We want to really start thinking about Rather than having just a right and the diffusional law why is it happening? And can we say where is where's that rock going to break and why is it breaking? What are the stresses that are causing it to break so now I want to And there's lots of stresses to think about so first of all I'm going to talk a bit about topographic stresses and the relief of and what we can say about how topography influences both Where surface prices are happening and also where the geodynamic prices are happening So I'm kind of going to flick back and forth between the two this is a another example from the researchers and in Tetonus and here The authors show just they just show quite nicely how the topographic stresses are reflected in The properties and so they've used a model to topographic stresses and then I've looked at P way of velocity and the P way of velocity Indicates where you've got Disaggregation and fracturing and groundwater flow and so you can see that there's quite a nice relationship between the the damage and and the stresses so this is the West Coast of the South Island and the alpine fault and We there's been a deep fault drilling program that's been happening over the last Ten years and their aim was to sample the alpine fault at death But for us and for this community, it's a fantastic opportunity to look at the interaction of the tectonics the topography the surface processes But for many reasons, so we've got a plate but boundary fault the alpine fault here It's a highly a bleak fault. So so it's got a strong component of strike slip and and and uplift on the hanging wall So the tectonics is three that the driving forces are three dimensional and then we've got the main divide back here, which is about This is about 20 to 25 kilometers and these peaks are three to four kilometers high And then the the range is cut by these these big rivers that are basically perpendicular to the boundary So it's highly three-dimensional system and it's complicated, but it's great. It's great for all the sort of questions. We are answering it It may try and decide where to put the drill hole quite complicated So There's a couple of just Things I want to tell you about the results from from this. Oh Which have lots of implications for the sort of questions we're talking about So this is the drill hole there So one of the things that and we knew that there was high heat flow in this region, but you know when we When we we drilled we drilled to we got to about 900 meters below Their ground surface and then we didn't actually hit the folks we ran into technical dish difficulty But by the but it down there We were getting the geothermal gradient was was you know over a hundred degrees Celsius per kilometer, which is Way high for any region that doesn't have a volcanic source. So really There was it was hot It's quite hot and the reason it's hot It's it's the tectonics the main reason it's hot is because of the tectonics These the rocks are being uplifted along the alpine fault faster than they can call but in addition to that we have a large a Large fault here, which the damage zone associated that fault means that the rocks and the hanging wall are highly damaged So we've got high permeability there and then we have this high topography which is giving a topographic driving force and so the Hopefully you can see these arrows on here. So The there's this flood flow that's going down the hill and then up into the valley. So there's we've got a Breakship rock We've got high high rainfall lots of rain. We've got a topographic driving force that's that's driving that water down that's picking up heat and it's Taking it up into the up into the valleys and so what we and actually today in our breakout group. So once we were talking about thermocronology and how important That surface processes etc might be the thermocronology and that is definitely the case here and that you know, you cannot put just you can't assume in the west and southern Alps that you are That your temperature great contours are gonna track With topography, which is a common assumption. In fact, it's exactly the opposite So you your thermal gradient beneath the mountains is is much lower than your thermal gradient beneath beneath the valleys and and this is because of tectonics and sir and what's happening at the surface and Both are you can't you can't figure out what's going on without thinking about both eight minutes So this is the same region But in this case, we're more looking at how the topography is influencing the the It's not the tectonics. It's influencing the structure. It's influencing where the deformation is taking place and Don't worry about staring at it unless you want to so again, we've got the photo rower Valley And this is the photo rower Valley here and what what we were looking at is if you've got the the Current oblique strike slip motion that's happening on the alpine fold does it enter does the topography influence where that Bolting actually takes place in the near surface and it turns out it does and it influences because it It rotates the stress tense it changes the stresses And so we end up and we can so we end up having a strike slip fault there and a thrust fault there And another strike slip fault there and are there because that valley is there and stresses bring me nicely to this that what we're calling the failure through response model and this is to try and use it and Earth to use a an approach to break to the failure of earth material so breaking the rock that's That takes into account the strength and the stress is the strength of the rock and the stress is because basically that rock will break If the stress is overcome the strength of the material, so if you're at a particular point You know you need to we need to Compute the local strength of the material look at what the stresses are that are impacting that material and If these overcome that then then we'll get then it will break and if it breaks It means that it's available to be moved from from where it is So in a in the landscape we have as I said, we've got this like we've got the tectonic stressors. We've got slope stressors fluvial Laceal Seismic it's short-term So Okay, so I'm gonna go through some results that we've got from from this model at the moment where we've built it in energy dynamic models flat 3d That's really is not an open-source model, but it's which is frustrating, but it's But it has what it has the capability to do what do what we want We're assuming that it's a completely supply limit so that we can we're not looking at transport We're not looking at sedimentation as soon as something breaks. We remove it from the system and That's a huge assumption, but it's useful and and it's a starting point So what we do in the model is we can sum all the stresses I'm tectonic if we depending on what our boundary conditions are tectonic GM or biology, but that the Tava graphic stresses we can impose Fluvial stresses and I'll show you example where we're using another model to do that And so we've just built this quite simple two ridges in a valley and we've we've built it so that This slope is stable this slope is is at failure because it's so steep and these two are kind of conditional It depends on it depends on what's happening to them And oh, this is this is useful to we can distinguish between share and tensile failure So we can look at where failure is occurring because it's it's failing and share or Because it's it's tensile so it's because it's being pulled apart so these This is a map view of the material properties that we've put into these into these Couple of examples. I'm going to show you this is basically just random heterogeneity with a weak zone down the valley and this is that but with these weak planes and added to the model and We've put in our model model glacier and and so this this sits here And in some models we we can put a velocity onto it and This is the stability field and I don't have time to go into this in any detail, but Basically what we can see is which bit of the model is stable and which bit of the model so which bit of the model is stable and so you can You know, you'd have to change either the stresses or the strength parameter for any failure to ever occur and which bits Unstable and so you could you can see like this backslope is Stable except that because of the loading of the Glacier here and the erosion on this side. It does start to erode back from from the rich here We see these weak planes and they we are not stable So that when you've got the weak planes are the only bits on the slope that's unstable. We see that the that the load of the glacier Strengthens underneath it, but that that transition between the load and no load is actually more unstable in these plots Red is is unstable and and blue is Is stable And I have to move on but if anyone wants to talk to me about this in more detail feel free This is an example where we're looking at at rock road ice velocity, so comparing a System where there's there's no ice where we've got a stationary glacier, but it's but it's so mostly it's a loading loading and here we we put a Velocity on it, so we're we're effectively simulating it a share sharing of the Sharing of that material as that ice moves along our substrate And we see and this is out. This is Sigma one. So this is that's the compressive stress and Here if we've just got a valley the direction of Sigma one is parallel to the slope If we if we load that with the ice the direction doesn't change, but the magnitude does if we share along here we can actually rotate so that This this biggest stress becomes parallel to that sharing of of the ice And I'm gonna move on So we've got Yeah, there's lots of challenges. Many of these have been raised already the time frames obviously Long-term tectonics versus what happens in an earthquake And again long-term slope Slow processes versus what happens in an earthquake Long-term climate variability versus what happens in a huge storm then Another big issue is imposing realistic surface processes onto this onto this model And Nick Richmond who's one of our students at Maine has been doing some of that with smooth particle hydrodynamics So he uses smooth particle hydrodynamics to calculate the fluvial stresses So instead of guessing the fluvial stresses, he's actually calculating them. So I'm gonna show you this movie really quickly This is a so he's we've built his build a model. This this model has strong and weak so the blue blue is weak and This is looked between firm and flak and the smooth heart particle hydrodynamics and so he He can calculate the Velocity magnitude and and the stresses that develop from that from that flow and Put it on to this code and then we see where we get Where we get failure and removal of material He's also done these quite these are not connected at all But this is an it's well, it's connected and that it's a tool So, you know, if you've got a river, it's really the boulders that are flowing down that river That are doing most of the work and this again is a smooth particle hydrodynamic model where We're modeling one tool, but you can see the stress that the stressors that develop first you see the stress from the waterfall and then So there's there's a stress from that and then you see the boulder So there's lots of implications for this and we've just really touched on some minor ones and Many of these I didn't really have time to go into at all, but yeah, the topography topography records Well, it hasn't had a plan isotropy and a lot of that is recording what's happened to that rock in the past from the tectonics from its Geological history, but in general we can say that valleys holes classes are weak high points tend to be strong and because they're staying there Stress gradients lead to erosion Tectonic stress I didn't really even talk about tectonic stresses, but Also, there's two things one that the tectonic stresses and strain Modified by ice. So I said that the ice can be Stabilized if you've got the load it can be stabilizing you get destabilizing effect from the velocity from the shear velocity or all the margins of the ice and The Sort of the opposite or not the opposite but related to that and the other way is that we find that glacial erosion is more efficient in the Presence of tectonic strain because when you've got tectonic strain that that rock is already sort of halfway to or part of the Way to breaking so you put whatever your driver is on top It's easier for that driver to break that rock if it's already strained Poor pressure is important. It was mentioned in the last talk and that can be incorporated into this any questions so my question has to do with how you use observations of rock strength in models and I wanted I think I think you We discussed in our breakout group as well as you sort of described in your talk how that's sort of a material Observable property that in many ways is a link between Geodynamic and geomorphic models, but I think going from field observations To actually implementing that in a model is not necessarily straightforward And so I wanted to see if you could comment on there are some of the challenges that you guys faced as you've been doing this as well As for many lessons you have It is a challenge. I guess this The the topography that we see is a constraint and yeah, I mean I I Think about cohesion and that sort of strength And I guess Sam would be a person to talk to about how you can that relates to an erode ability But you know we in a actively deforming landscape where you know you have these seismic events and or even where you don't But the slopes that you see and in the topography that you have is a constraint it tells you How strong that rock has to be and I guess it it tells you something about the erode ability to but I yeah How you get a number of that? I can answer I just wanted to actually focus in on something I've been really intriguing when you were comparing the formation of the uniform strength versus The weak trough versus strong sides You had these very interesting deposits. You're looking particle resonance time And you have these I guess you from the Milluvial fans of course material And actually then took a much longer resonance time than the rest of the landscape And they also protected the underlying weak bedrock is this modeled within child Um, yeah, Sam's right behind you and he did it but yes, it it was done with a child Anyway, I just thought it was really quite fascinating Talk guys curious to know how distributions of you know gravel along the Normal fault would rather than spreading out across the base Detail would probably have some impact So I'm not actually going to answer your question I'm going to ask a different one, but I'm happy to talk about it more So this is really cool because this is trying to get a physical interpretation of what Kay might mean rocks themselves and so in this case you're indexing damage strength on Being at failure, but there's a lot of damage that can grow subcritically right when you're not at failure And that has a time scale to it. You think that's a time scale we should worry about or you think it's fast enough relative to landscape No, I think I mean time scales is this I Think the time scale is important and I think Yes, yeah, well actually one of the so in a in a mountain about like the damage done I talked about in the alpine fault, you know I just talked about damage and that it's caused by the tectonic stresses and the seismicity, but at the same time you've got healing so So you can actually bring a whole component of chemistry into there because you know, we've got hot fluids We've got lots of circulation So some of those fractures on even on a seismic cycle are gonna heal and and we see them We we see those fractures in the drill hole where you've got quartz and calcite So yeah, there's there's a lot there'll be some critical stuff It'll be time to time the time frame and then there'll be other processes that are either enhancing or slowing down Thank you again. There is a break now. So there's coffee And I have a salmon for Michael Barry