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GEOL6351-Basin Modeling - Day2 09-24-2022-AM
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00:00 we're gonna start. Perfect. Right let me share my screen and we're
00:14 take off where we left yesterday. that is um we're looking at a
00:24 earth. So I'm gonna repeat where start where we ended yesterday and then
00:30 gonna go from there. Okay so we started with this cursed that consists
00:37 an upper crust and a lower And underneath we have demand a little
00:43 . So here's the upper crust and gonna go over it again because it's
00:47 really need to know all of this we continue with the rest of this
00:53 and tomorrow. Going up across the course a mental little sphere. And
01:03 their mental little sphere we find the . 10 0 sphere. Now the
01:11 between the cursed and the mantel is the mojo. The boundary between the
01:17 sphere and the ionosphere. Or the little sphere. And the ionosphere does
01:21 really have a special name but sometimes people call it the L.
01:25 B. Which stands for a little . A steam atmosphere boundary. Yes
01:34 have an upper crystal, oh cursed Mental little sphere sphere estimates were boundary
01:40 an esteem a sphere. The other that we looked at were densities.
01:47 if we talk about continental little sphere of course you can say it has
01:52 density let's make 2700 kg per It's often assumed to be a little
01:58 lower than the lower curse. Let's 2800 kg per cube. For the
02:03 curse. It doesn't really matter that for this course the mental little sphere
02:08 a density of 3300 kg per And then under that we have the
02:15 a sphere of the density that's a bit lower. Let's just make it
02:19 200 kg per. Cute just to things easy. Alright. We also
02:30 about a normal crystal thickness or normal depths and in the continent it's something
02:36 30, 40 km or so. just gonna put 35 km here but
02:41 place to place, that number varies in the depths of the little boundary
02:48 the continents also ferries from place to . But we can take something like
02:54 or maybe 125 km. So that you an idea of what we're looking
03:03 the upper crust. We set deforms behaves in a brutal manner. Which
03:11 that if you you know put too stress on it full to start to
03:17 and the lower crust reset behavior. doctor manner. And then the mental
03:24 sphere below it is fiscus. I'm talk a little bit about that later
03:30 morning. What that all means. the Osteen o sphere is fiscus as
03:41 . Now the brittle ductile transition. the upper course lower cross transition.
03:46 basically a temperature, you know, an isil term, somewhere where you
03:50 a certain temperature, if temperatures are than the temperature it is very difficult
03:56 faults to form in crystal crystal So then we have doctored information.
04:01 at lower temperatures in the upper we have brittle deformation. At higher
04:06 in the lower cost we have dr . Now the brittle ductile transition um
04:12 know what temperature exactly that happens varies little bit from place to place.
04:17 I'm just gonna put a temperature So, you have an idea of
04:21 we're talking about. I'm gonna say maybe around 375°C. The temperature at the
04:33 of the curse. So the the boundary between the crust and the
04:38 little sphere fear is also strongly from to place. I'm just gonna put
04:42 temperature down here um let's say 600 700°C, okay. But it can be
04:49 lower than that and in other places can be higher than that. But
04:53 is again, just to give us idea of what we're talking about.
04:59 then at the base of the mental little fear of sickness, fear boundary
05:02 L. A. B. Many think that this was also an isil
05:08 and that the temperature here is something 1300°C. So let's talk about this L
05:23 . B. For a moment So if the L. A.
05:27 . The little sphere assed industry boundary an ice. A therm 1300 degrees
05:32 , it means that if you start heat up this area. So maybe
05:38 comes in from below. Maybe there's mantle plume or whatever process that's going
05:44 . It means that a little fair three boundary is gonna move up.
05:48 see that if you heat it this boundary is gonna move up because
05:54 an isil serum questions about this. , ma'am, then let's see,
06:18 move on. So when we talk sedimentary basins, these sedimentary basins form
06:30 of some kind of tectonic process that's on and these tectonic processes, they
06:38 because of forces that act on the on the tectonic plates or plate boundary
06:46 . So there's forces acting on the the little sphere, the tectonic plates
06:53 the earth, the forces acting on little sphere. I'm gonna go over
07:00 few of those because they relate directly the sedimentary basins that we were talking
07:05 yesterday. So, yesterday, remember talked about the different types of sedimentary
07:11 and those were atomic basins or platform were were inter contra tonic basins or
07:18 basins. We talked about rifts, rift of margins. We talked about
07:30 land stations, reflection will basis. talked about four art basins and back
07:41 basins. Um I think the deal it briefly yesterday for our back arc
07:49 apart basins. So, those are the different type of basins.
07:57 what I'm going to talk about next how um you know, tectonics writes
08:04 is driven by by forces, how form these different types of basins.
08:08 it's a very brief overview. I'm not gonna talk basin by basin
08:13 , but I'm gonna talk tectonic area tectonic area and force by force.
08:18 the first one that I'm going to about is what happens at subduction
08:32 The subduction zones. As you remember , those are the places where ocean
08:35 gives your subjects into the mantle. , I'm gonna sketch here in mid
08:41 spreading rich. This here is the mid ocean spreading rich where the oceanic
08:49 is being formed and then the oceanic . Eventually oceanic little sphere eventually subjects
08:58 drives into the mantle. So this is oceanic oceanic little sphere or an
09:08 plate and that oceanic little sphere also of a thin layer of oceanic crust
09:17 a layer of oceanic mental legis Now, here's the other side of
09:28 subduction zone system. Here is the , continental little sphere. So
09:37 the continent. This here this here two volcanoes. So this is what
09:46 sometimes call arc magnetism. And again the art magnetism is there because fluids
09:57 are in oceanic cursed ocean atmosphere, come out of this slab, they
10:02 up forward. This is this now to melt right. The estimates for
10:06 rocks here start to melt the molten move upwards and then reform volcanic
10:14 This here, the oceanic little sphere being seductive. We call that a
10:20 an oceanic slab and then here again the left is the mid ocean
10:32 Any questions about this sketch is already where, what we're looking at here
10:38 they were going to go from Alright, sometimes it's not, sometimes
10:42 just a spreading center. Sorry I sometimes it's not a ridge, sometimes
10:49 just a spreading center, correct? this is the Yeah, I'm sketching
10:53 here as a rich but this is location where new oceanic crust is being
10:59 so that that's the meaning of that the rich there. Alright, so
11:08 start with the first process that is to us and that causes the formation
11:14 many different types of sedimentary bases. this process is called slap rule
11:28 slap, roll back. So what we mean with that? I'm just
11:34 sketch the same slab as I sketched the upper sketch. So here it
11:40 your oceanic little sphere that starts to you recognize the sketch right? And
11:48 back means to following when this oceanic sphere moves away from the spreading rich
11:55 it's it's it's pulled down here into mantle. This is not like a
12:01 about. So it's not moving around certain point, it's not doing
12:07 What it does is that this lab heavy, it's high density material.
12:13 accursed oceanic mantle, little spheres high material, so it actually sinks into
12:19 mantle, it wants to sink. you can already see it a little
12:24 when it does that, it tends roll back. This is what we
12:29 with it. So it rolls back that, you see that and then
12:36 10 million years from now, maybe does this we call that rollback.
12:45 the slap instead of staying this, um this point here staying in the
12:52 location it moves in this location, see that it's a little bit unclear
13:02 me. Um let me try to it again. Here's the ocean,
13:11 the ocean and atmosphere, right? abducting into the mantle. This is
13:15 slab. Now, this slab is material, high density material. And
13:22 it does not want to stay it seems as a result of gravity
13:30 the mantle. And when it does , it's um it may start
13:38 This sinking maybe faster than the movement this oceanic plate in that direction.
13:46 if this sinks faster, then the is being, you know, renewed
13:52 and moving in that direction, which do in the next time step,
13:58 slap, I'm just going to sketch top of the slab. Now,
14:02 time step, it's here. Next step, it's there. Next time
14:08 , it's there. You see that rolling back towards the mid ocean,
14:14 spreading center. Now if this rolls , just putting the arrows in
14:23 But you get the point if this back like this in this direction,
14:29 was here, another plate, Maybe a continent continent. If this
14:36 back, there's not gonna be a year here. There are no holes
14:42 the earth. There's not gonna be gap or a whole. What's gonna
14:47 is that this continent is gonna basically its own way. It's allowing itself
14:53 extend in this direction to fill up hole. So the next time step
14:59 could be groups. This is a weird slap. Sorry about that.
15:02 could be that the slap has rolled and now the continents with the volcanic
15:08 that was present over here starts to in this direction basically to fill up
15:15 space that was that was available. . The continent may undergo some
15:23 It extends in this direction. Does make sense or not? Yes,
15:29 . Yeah. So there's no there's a whole right every everything on earth
15:34 take up the spaces can take Now this extension doesn't always happen
15:40 Sometimes the continent may move in this . There's not much extension. But
15:44 can see that if you roll back right, you allow the continent to
15:50 if it wants to extend in that , it now can do that.
15:56 there may be extension. Now when start to extend a continent and now
16:03 know, maybe the subduction zone was , we're now gonna look at the
16:07 itself if this continent is now allowed extend at that point in time.
16:18 you start to extend that you start extend that you've seen it. And
16:22 extension and sinning may result in the of a sedimentary basin. Maybe a
16:27 basin right here, just sketching it this. This can go here.
16:37 now, here, this is a basin. This here is the
16:43 this is the cruised. When when extend the little sphere, the christians
16:50 the mojo often comes up a little . You see a thinner crust
16:54 you see that thinner than here and and then here I sketched the literature
17:00 fear boundary. So this is the little sphere and this is the esteem
17:06 sphere. And also you can see this Christina sphere boundary has come up
17:10 little bit. So here we've now a rift basin and risk basin will
17:18 filled with sediments, etcetera. So means that when an oceanic slab,
17:25 atmosphere, when it's when it starts roll back, the continent has a
17:31 to extend. So, if the wanted to extend because previously it was
17:35 under compression. Now you allow to and as a result of that,
17:40 may start to form rift basins. rift basins, they may form closer
17:46 the trench, but they may also very far inland into the continent,
17:51 doesn't really have to happen close to subduction zone. It can really be
17:56 kilometers or more inland. Now, is the way that we can form
18:03 continental rift zone or maybe a back basin and more about back arc basins
18:09 the third weekends. And then here be the volcanoes of the volcanic
18:17 Questions about this. No, Alright. Now, next thing that
18:26 happen with subduction zones is the I'm gonna sketch another subduction zone,
18:32 this one looks a little bit So towards the left here, we
18:35 again, oceanic spreading center, here's slab and now our slab, instead
18:42 diving deep into the mantle, we're to say that this slap doesn't dive
18:48 its light, it doesn't want to and it's gonna stay fairly horizontal before
18:54 dives down later into the scheme of . So this is again our oceanic
19:00 here, let's assume that this is continent again, continent. So now
19:08 have a different situation instead of this going down, It doesn't want to
19:14 down, it's like material, who what's going on. So it stays
19:19 for a little while before it goes . Now, maybe this distance is
19:23 km or so, it doesn't Just gives you an idea. Now
19:27 can already see that the situation here very different. You can imagine that
19:33 slab here, if it doesn't want go down, it's gonna push against
19:38 continent. You see that these plates gonna push against each other, there's
19:43 be compression. Now, what happens we compress a plate? The plate
19:54 probably start to deform and it may to deform by forming fall first belts
20:00 mental or sorry, mountain belts. , so it starts to deform,
20:05 starts to sicken of course, starts sicken. We start to form full
20:09 spells. And an example of that be the Rocky Mountains in the United
20:16 , the Rocky Mountains. So now are in a very different situation.
20:24 compressed this continental plates, we start compress it, we start to deform
20:30 and we may form false response. these folks first bouts, you can
20:37 of see it from this sketch but I'm gonna sketch this in more
20:41 on the next slide. So, faults. First bells. These are
20:48 oops where crystal slabs basically fought over other. This shouldn't be here.
21:06 , so this could be a fault belt for a mountain belt. So
21:15 is crystal material, this is crystal , this is crystal material, this
21:19 crystal material verses here. Now, you can see something else that's going
21:30 this here. This is all that's kind of kind of folded and
21:36 on each other. Right? So extra crystal layers here on top of
21:42 that was already there. This is the curse, that's already there.
21:47 this is extra weight on the This extra weight this this this
21:54 we're gonna call it a load of crystal material is gonna bend or bends
22:03 the crist you towards the right. we create a space and this space
22:09 can start to fill in with This accommodation space that that forms because
22:18 this loading here, the heavy rate bends down the little sphere. This
22:24 called a flexible basin or a foreland , flexible basin. So because of
22:35 compression that occurs at the plate boundary the subduction zone, we started to
22:40 the continents. It's gonna deform. gonna form these three thrusts of continental
22:47 that slide over each other, that on top of each other this year
22:51 now an extra load of material on crust that was already there as a
22:58 of that, the crust is gonna down, you bend it down,
23:02 create some accommodation space for settlements to deposited in and you form a sedimentary
23:08 . So, this is one reason we have flexible basins or four land
23:21 , but doesn't the crust flexes beneath the mountains and then it's on the
23:29 the inboard edge of it for the with the four landforms. Right,
23:33 that right, correct? But but we'll see later today is
23:41 Is that this crystal here, this the moment, right? The chris
23:45 I'm sketching here at the top of um sketch this chris has strength.
23:51 , if you have a strong, see how I can show it maybe
23:56 this. It's not gonna work. , if you put a load on
24:01 , this is a pet writing If you put a note a note
24:05 that, but it's gonna do, gonna bend like this, right?
24:08 it has. And so even though loads, maybe only here, this
24:15 occurs over a larger distance was a distance to create some space here,
24:22 depression that will be filled in great still there. Let's see um She's
24:37 there. Yeah, so it's the same situation here. Um So we're
24:42 talk about that when we talk in about four earth bases. But here's
24:47 subduction zone, right? This was subjecting slab here. You can see
24:51 volcanoes that form the magmatic arc. , these volcanoes volcanoes by themselves,
24:58 a power of rocks that can you know, 10 km in diameter
25:03 more than that. It can be km high. So that's a pretty
25:07 mass. So you can imagine that large, large volcanoes, a large
25:12 system will also start to bend the . So this here is gonna bend
25:17 a little bit. You see that the volcanoes and this is here that
25:22 can create you create a depression fill with sediments. This would be part
25:28 your fore arc basin system. So in your lower diagram, you don't
25:39 an arc in that, but there be an arc somewhere because you
25:42 oh the ark is out further import the thrust, you're saying right and
25:48 this moment it's it's actually on the side. And at this moment,
25:55 here would not be active because we have those fluids coming out of the
26:00 , They're coming out of the slab , here you see that here,
26:04 nothing going on there coming out of slab here. So your your access
26:09 will be there. So with the american flat slab, where where are
26:17 volcanoes at? So these are um sun wants the volcanic fields. The
26:27 of volcanic fields in New Mexico and Arizona and the Pecos volcanic field in
26:35 texas and east aren't those volcanic fields to the Rio grande rift?
26:42 they're pre they're older. So there about um 40, million years
26:51 And they are cut by the first of the Rio grande rift. So
26:56 is how know this? So these um they in in um New Mexico
27:13 those volcanic systems and easternmost Arizona and most Arizona colorado. These volcanoes,
27:22 are arc magnetism from when in the US there was this flat slab that
27:28 to dive in the mantle somewhere here then these are those are large old
27:35 volcanic systems. So they became extinct um you know the main post of
27:43 was around 35 40 million years So we know that around that time
27:48 the end of the, you know maximum extent of the flat slab,
27:52 started to roll back and then these system slowly became an access. So
28:01 dates to three dates the San Andreas system. So the so the cascades
28:07 the arcs uh the lander, I'm to waste time on this stuff and
28:14 just trying to connect the dots because the northern, you know up up
28:19 around you know at the US Canadian , you have, you know you
28:24 you have a seductive slab and it's art rocks down in through down to
28:31 mount ST helens and further south to Oregon and Washington. And then in
28:40 , what happens? And it's in there and eastern Arizona, what happens
28:48 the ark? So this is the U. S. Coastline. It
28:53 a bit like a sketch about, make it a sketch. So today
28:58 have the san Andreas fault here. , this is baja California, This
29:04 California, this is the San Andreas system and it's a tertiary right?
29:09 San Andreas developed in tertiary right? last last 20 million years, just
29:16 I thought it was a little Okay, anyway, maybe 25
29:21 maybe the first time 28 you're the on that part. Alright, so
29:31 here is a transform fault in oceanic sphere, there's a spreading which in
29:39 here and this here, it's a zone. So, um and then
29:47 in Oregon and Washington, Are these of which Mount ST helens is
29:55 Does that make sense? Yeah, just but it's a trans transform that
30:03 all the way through California san Andreas a transform. Right, okay.
30:08 then and then you have them and said eastern Arizona and western New
30:14 You have So this this this type folk in Ism was probably arc magmatic
30:27 volcanism that forms when the flat slab basically covering this up. So that
30:35 slab extended until it doesn't have to that March, but say somewhere around
30:41 and then these large caldera systems formed that. That's what people say in
30:49 . So there's an offset there. Oh, I see. You just
30:53 just project the mendocino in board and say that's where the opposite is.
30:57 see. Okay, Alright. Didn't to take up class time with my
31:02 questions. All right, So we talking about seduction song, right,
31:12 boundary. It can cause extension of continent. It can cause compression of
31:17 continent dependent on what's going on If it causes extension, it forms
31:23 such as rift zones if it causes , it forms mountain ranges. So
31:29 is the rocky mountains that loads the sphere that loads the tectonic plates and
31:33 a result of that, we can flexion basins of foreland basins and you
31:38 see an example there, Yeah, move all now. Um So the
31:46 example, the next next time we're take a look again at the subduction
31:52 area. So this is again this little sphere or oceanic plate that is
31:58 subjected to a gynecologist slap. And here is the continent. So same
32:04 again, continent is here. Now take a look in detail at what
32:11 right around here. So if you at oceanic cruise oceanic atmosphere, it's
32:19 thin layer of crust Maybe seven km or so that overlays a layer of
32:28 mental atmosphere. So this is a that I'm sketching here of this plate
32:39 crystal layer here and the mental atmosphere . But there's something missing in this
32:46 . On top of this oceanic on top of the ocean crust is
32:50 layer of sediments just gonna sketch it here and the settlements, they consist
33:04 verifying verifying much particles that basically rain in your ocean basin and also,
33:15 know, skeletons of of of of and whatever lives LG whatever lives in
33:22 . Right when that dies, it down to the bottom of the
33:27 it is being deposited on the ocean and it becomes ocean sediments. So
33:33 other words, when we're here at place where the oceanic plate subjects into
33:40 mantle at the subduction zone. This plate has a layer of sediments on
33:46 of it and the layer of sediments be kilometers thick, that can be
33:51 pretty thick layer of sediments. what happens when with that layer,
33:57 this oceanic plate reaches the subduction some of those sediments, they go
34:04 in the subduction zone, they're still top of it and they go down
34:08 they give you some of the water is removed here from the subduction slab
34:14 the mental material here and causes the is um at the surface. But
34:19 of those sediments, they never make down there, scraped off. So
34:29 scraped off as this oceanic plate goes and they're scraped off and at the
34:34 time they're added to the continent Yeah. So these are scraped off
34:42 used to be on the ocean floor that are now piling up here on
34:47 edge of the continent. So these have a name, will come back
34:54 to that in the third weekends. sediment power is called a creature
34:59 which creature binary. So that piling is called accretion secretion of sediments that
35:11 from that subjecting oceanic slab and they're they find their way onto the continent
35:18 . So now we have a situation we have a power of sediments
35:22 We have volcanoes either active or non towards the right there and then in
35:30 here you can see you form a bit of a basin as a result
35:37 the loads of that. These volcanoes . This is called a sack a
35:41 bit. The same is gonna happen . Maybe the slap here pulls down
35:46 the plate. So you have a bit of subduction of subsidence here.
35:50 other words, you create a space , you can start deposit sediments.
35:55 sediments would come from the volcanoes, rock steps are being eroded and the
36:01 can come from this missionary ridge. gonna fill up the space here and
36:06 form a basin here. This would called a fore arc basin. It's
36:13 basin, whoops. That is located the foresight. The subduction zone,
36:19 of the volcanic arc questions, Right now we're gonna move away from
36:44 zones. Now we're gonna go to different type of location in continental
36:49 Let's talk about the san Andreas fault . I assume that you've all heard
36:55 this forts on the san Andreas fault California just came up. So if
37:00 is the California coastline here is baja Mexico, I think we all know
37:09 this is the north american plate. here the plate boundary between north America
37:20 the pacific plate. Oops, is transform fold and it transformed fault.
37:32 should remember that is a fault along to crystal blocks move in opposite directions
37:40 respect to one another. Strike slip or transform fault, you call it
37:44 transform fault. If it cuts the plate, the entire little sphere.
37:50 um and and you know it separates north american plate from the pacific
37:55 That's when you call it a transform . If you have a fault like
37:59 where you have crystal blocks moving but fault is not as deep, you
38:03 call it a strike slip fault. have heard of that as well.
38:10 transform faults and strike slip faults. when we sketch or we look at
38:16 large map of these faults, it like this right align and then the
38:21 plate moves northward or northwestward with respect the north american plate, this is
38:28 you see it sketched. But if look at in detail at this photo
38:32 see something that's a little bit different I'm gonna sketch that next. So
38:37 the detail specific plates moving in that . North american plates moving in this
38:44 and now we're gonna look in detail this transform fault. This transform
38:49 it's not one long fault, what is, it's a series of shorter
38:57 that are located like this too short fault segments that together make up the
39:04 faults. The san Andreas fault Now if you move um this plate
39:13 this direction and this played north american in this direction. Let me just
39:20 um if I sketched it correctly. . So if you move this in
39:29 direction and this plate here moves in direction. Let's just look at one
39:37 of the SAn Andreas fault system. move this in this direction and this
39:42 this direction. You can imagine if moves like this and this moves like
39:48 , that in this area here, gonna pull off open the crust,
39:55 gonna pull apart the crust this year be called a pull apart basin or
40:07 slip base and pull apart basin. see that? So if you look
40:12 the large transferred for a transform fault or a large strike slip fault
40:17 it's never one fault like that. always broken up in short of fault
40:23 and then the shorter fault segments, not they're not perfect like this.
40:28 see that there's always an offset between . So they're like this or they're
40:34 this. And then in between at this step over between these four
40:41 , that's where you can start forming basins. And we call these basins
40:47 apart basins. There basically rift basins we're literally extending the crust right
40:55 But there's a difference in shape, very deep. Um And they're much
41:01 in size. So I called pull basins. Alright. And then there's
41:16 more uh important tectonic environments or two that I'm gonna explain to you to
41:24 like forces. The first one is following. We're going to look now
41:34 a mountain range, maybe the This is a cross section through the
41:40 . It doesn't look like it. just to to imagine that those are
41:45 , the Himalayas and here we have base of the crystal mojo. And
41:50 can see that's underneath the Himalayas. crust is very thick, much thicker
41:58 in other places. So the the base of the crust is found
42:02 larger depths maybe at 60 kilometer steps of the 30 kilometer steps. And
42:07 the surface we see this high mountain , the Himalayan mountains. Now at
42:14 point in time the indian played that find towards the south, here's north
42:22 , it's no longer gonna bump into . That's gonna stop it from point
42:26 time. And what's happening at that in time. Then we're still left
42:32 with this large mountain range. But is compressing it further. So nothing
42:37 keeping it together. What's gonna happen is the following, this mountain range
42:44 start to collapse under its own And you know why that is it
42:54 because it has what we call gravitational energy reputation of potential energy. So
43:11 energy or gravitational energy that is energy is stored in a mountain range because
43:18 its its height and so on the time scale, hundreds of millions of
43:26 . The Earth does not want, know, presentational high mountains to be
43:32 out its attempts to flatten its That's what everybody would do,
43:38 Every body that is in a gravitational would like to smooth this out
43:44 it's being smoothed out because of erosion sedimentation, erosion and weathering anyways.
43:50 added to that is this gravitational collapse that will happen. This is not
43:57 that will happen fast. It will over tens and tens of millions of
44:02 . But eventually this mountain range is collapse like that. It's not gonna
44:08 spectacular. That's a slow process, it's gonna basically gonna fall apart.
44:12 can already see from the arrows that drawing here, that gravitational collapse under
44:18 own weight. These arrows are pointing . You see that. So that
44:24 that this mountain range or portions of may become under extension. So within
44:35 mountain range, you may start to rift basins and you know what that
44:44 already going on. So, if you look at the Himalayas,
44:49 have identified some of these rift smaller basins in the Himalayas that give
44:55 the idea that this mountain range has to collapse under its own weight.
45:05 about this, No, ma'am. then, the last force that I
45:18 to talk about that's that's forms sedimentary , that is the earth's mantle or
45:31 flow or mental confection. So, confection is another word for mental
45:45 So, I'm gonna sketch here, portion of the earth and this here
45:49 the upper part, it's the little . And underneath the little sphere,
45:57 know, we had the esteem a , right? And then underneath that
46:04 the transition zone and then underneath that had to lower mantle. Now,
46:18 sure you've all heard of mental the earth mental is not laying still
46:23 over the course of millions of it is conflicting, it's flowing and
46:29 way it's flowing is often in what call confection cells. So I'm gonna
46:34 one of those confection cells. Maybe year is a confection cell and um
46:43 here there's an area where the mentor welling up the confection sell.
46:53 you may wonder what is going on . So here we have have mental
47:00 towards the right on this sketch. ? And on top of it is
47:04 little fear this plate, little sphere . What is happening here to some
47:14 think that this mental confection here may drag or share this plate above.
47:23 some geologists think that if you would in on this area here, you
47:28 have here, the little stick the base of it, so the
47:31 A. B. Let's first industry and below it, you have confected
47:37 and that is confected mental. These , they basically drag um drag on
47:44 base of the little sphere. So pull it right along with the mental
47:50 and these people think that maybe that some deformation here in the place.
48:03 I have to say there's not much for it, places on earth,
48:08 looks like that, this might be on, but not certainly not
48:13 You can imagine if you start to on the base of the little spherical
48:18 that you started to form this says information that you start to deform at
48:24 spherical place and maybe deformed in such way that you start to form a
48:29 in here. So that's the idea this. So it's called mental people
48:34 it. I think sometimes mental drag this force exerted by the esteem sphere
48:45 the base of the little sphere would called a basal traction force, a
48:55 attraction force. Now there's discussion going on how important, no different
49:07 different thing, I'll explain it in sec. This is really the conflicting
49:13 the large mental confection that is dragging the base of the little sphere based
49:21 force. Now, what I have say is that um it's a minority
49:27 geologists who believe that this is Most geologists don't think this is that
49:32 , but I want to mention it you because you may read a paper
49:36 on in your life where somebody is about this. Okay, so
49:40 you know, some people are talking this, what's more important is what
49:45 what I start to sketch here towards right side of this um figure.
49:50 I'm gonna zoom in on that. now just gonna look at the plate
49:56 then an area where we have mental going upwards upward flow. This could
50:03 a mental clue or this could be a zone in the mental where you
50:09 concentrated, strong mental up, flow flow or upward flow of material in
50:17 mental years. Again, the little and this would be the little fear
50:24 sickness, fear boundary apart show. this is more important. Many geologists
50:35 that this can be quite important. , again, this mantle plume may
50:38 from all the way the base of mental rights that deed of a prime
50:43 that is located directly above the So here we have the plume coming
50:48 . Now, what is plume is to do is the following,
50:55 it's moving upwards in the mantle and moving upwards it is causing this.
51:02 top of the little street here actually little sphere as a whole two brooch
51:14 above it. So this is the effect as what you could have in
51:18 bathtub. If you if you fill bathtub or a swimming pool with water
51:23 you put your hands flat underneath the and you move your hands up,
51:28 in the water underneath the surface. see the surface of that pool of
51:34 bathtub, that water moves that the will start to deform. If you
51:38 your hand up, you will move surface up. If you move your
51:42 down, you will drag the surface the surface of that fluid. The
51:47 effect happens in the earth. So move mental material up the surface
51:54 It is gonna go up. You mental material down, concentrated way the
52:00 above it is gonna go down. call this broaching upward or that's that's
52:09 that forms when the mental moves We call that topography. And that
52:15 is called dynamic topography. So, topography is topography of the surface.
52:28 surface of a fluid that is caused stress is vertical stresses that are exerted
52:35 the base of that that surface by flow of the fluid. That will
52:39 the definition. Now, you may , well, you're talking about the
52:43 and we're talking about the Earth. , but it's mental conflicts,
52:49 It acts as a fluids on very timescales timescales of hundreds of millions of
52:58 . So that mental confection and mantle going up even though that occurs very
53:04 . It does tell us that that fear the transition zone, lower
53:10 the upper mantle of the earth, act act as a fluid. But
53:19 fluid is just very viscous. It's like water, it's very viscous.
53:23 it's, you know, the viscosity the viscosity of a rock. So
53:26 very slowly moving. Now this dynamic , the uplift above it or the
53:35 if you have down going mental um there there's some evidence that this could
53:43 important information of some sedimentary basins. take a look at the at the
53:49 the right side of the sketch You can imagine that if your mental
53:55 downward and this mental confection is very . So this slowing this slowly moving
54:01 may go on for 50 million years maybe 100 million years. You can
54:08 if you drag the surface of the slowly down over a long period of
54:12 . This here this space is gonna filled up the sediments and you might
54:18 a sedimentary basin. You see So you can see that there's a
54:24 between mental flow and sedimentary basins. also a relationship between these these upwelling
54:32 or strong zones of upwelling and sedimentary . And we're gonna talk about that
54:37 the next hour. Alright, so summarize this. So um at seduction
54:47 just repeat about the basic attraction Yeah, go ahead. I just
54:54 to hear about the base interaction I didn't get it right the first
55:00 . Okay, so um well let start from, let me start repeating
55:04 door and then we'll get to that traction force. Okay, let's start
55:08 subduction zones. So we sketched the zones. And then we saw the
55:15 where the slap will start to roll , We may extend the continent that
55:23 cause the formation of rifts. Then saw that there are situations in which
55:30 slab basically compresses the continent maybe because doesn't want to go down compression.
55:40 that particular case, you can start form mountain belts for thrust belts and
55:45 may start to form foreland basins. we saw that also here, closer
55:55 this trench, a lot maybe going . Maybe there's extension here because of
55:59 slap, roll back and you form basin here. Maybe material is scraped
56:06 from the sub ducting slab piled onto continent into a creature Neri arc,
56:12 accommodation space behind it and forming a in there. Other plate boundaries that
56:19 looked at is if you have a fault plate boundary. So for
56:27 the SAn Andreas fault, in the of the san Andreas fault, we
56:31 the pacific plate here in the north plate there, the pacific plate moves
56:35 that. The north american plate moves that. These um transform faults,
56:42 slip faults. There never one contained , but they're always segmented into smaller
56:49 and an empty step overs of these . You may start to form pull
56:54 basins. Now, then we looked forces that may act on the base
57:02 the little sphere plate. This is little sphere underneath it. We have
57:10 confection. Maybe. I'm sketching here confection cell, maybe this mental confection
57:19 . These these these rocks of the a sphere that are moving in that
57:24 . They're exerting attraction force here at base of the little sphere. So
57:31 gonna start to drag the base of little sphere in its same direction.
57:37 that attraction force. You can imagine if you would do that, if
57:41 would start pulling like that on the of the little sphere that you would
57:45 deforming the little sphere, that's more McIntyre. So it's the fourth which
57:57 just moving the plates towards the little for the force exerted by the conflicting
58:06 flowing mental below. So, this your mental below, right, This
58:10 flowing, it hits the base of little sphere and it starts to it
58:17 attraction, it doesn't flow, you , without friction or so it feels
58:23 , so it starts to drag it it, that's basically what it's
58:28 Um Sometimes people call it a drag . Thank you. Yeah, then
58:40 looked at gravitational collapse, if you a mountain range that is no longer
58:45 , you know, compressed significantly, will start to collapse under its own
58:51 . And when it's starting to collapse its own weight, it may start
58:54 form rift basins within that mountain maybe there and there. And then
59:03 we looked at um you know, is a little thick plate, we
59:15 at maybe, you know, a plume coming up or maybe there'll be
59:20 other area where there there's concentrated mental going down. This may result in
59:28 topography and the dynamic topography could also a depression, right? It can
59:34 uplifted at dome. We sometimes called a dome and we could call this
59:40 depression. And you can imagine that depression can be filled up with
59:49 You can imagine that this dome may to erode. Yes. So,
59:56 are the main forces associated with the plates in geology and the main driving
60:05 for why we form the sedimentary basins different locations. Questions about this,
60:23 , if you have no questions for , um it is now 9:39
60:29 What I suggest is that I'm gonna sharing is that we take a short
60:35 and then I'm going to talk about basis. Right? To see you
60:43 about 10 minutes or so. Perfect. Great. Alright. Type
60:53 basis that we're going to talk now our atomic basins and um platonic basis
61:01 sometimes their their calls. Um So called tectonic basins called tonic or intra
61:11 nick or platform or sack basins. so all these names make sense.
61:22 I'm gonna explain you why next. , here is a map of part
61:30 the earth and these figures, they , by the way, come from
61:33 allen and Allen basin analysis book. Mac was part of the earth showing
61:40 cra tonic basis in this part of earth. So let's focus on north
61:47 we have here, the Williston We may have heard of that Illinois
61:53 , michigan basin, Cincinnati basin. there's a very large run in Canada
62:01 Bay basin. I'm gonna point out few other ones in South America.
62:09 am gonna point out the amazon basin in africa, I'm gonna point out
62:19 , it's called here, that's the basin, basically, basically the Congo
62:23 . And here the Child's Basin. in europe, I'm gonna point
62:30 um, let's call it this one the Moscow platform. No, what
62:39 all these chronic basins have in common the first place? Let's let me
62:43 about one other thing related to this . So, you see here that
62:47 cra tonic basins are indicated either with circles with the song colored circles or
62:55 blue colored circles. And they give the age during or or the time
63:02 Earth's history when these basins started to . So the blue ones are the
63:08 , they started to form in the Cambrian, the yellow ones, the
63:13 circles started to form in the Cambrian the sum or pink colored circles started
63:19 form in the order vision. So other words, they're all very
63:25 And so, um, you let's take a look, I'm gonna
63:29 a lot about the real stone basin the michigan basin here. So the
63:35 american ones. So, these basins to form initially in Cambrian times.
63:44 a long time ago, hundreds of of years. And since that time
63:50 atlantic ocean started to break up before we had continent continent collision. We
63:57 the formation of the Caledonian and the mountain ranges. And so a lot
64:03 happened over the lifetime of all these basins. And that is important to
64:11 in mind because all the tectonic events happened over there, hundreds of millions
64:16 years lifetimes, they have affected those basins. Sometimes they may have resulted
64:23 a little bit of deformation in the maybe some folding and the folding and
64:29 anti clients or the dome structures that as a result of that are now
64:33 present day traps. So keep that long, uh, very long life
64:41 in in the back of your Okay, now, the other thing
64:45 you may notice is that all these , these platonic basins are on the
64:50 course of the continents. So, example, if you look at the
64:54 american continent, this here is the core of the continent. It's the
65:01 little sphere that we have. And little sphere here in this area is
65:06 than one billion years. And in places, it's much older than that
65:16 . Does anybody know here about the of ages of the oldest continental little
65:21 of continental crust anywhere on earth? , close to four billion years
65:29 It would be the oldest are key Aurel are key and there's bits of
65:34 up here in western Greenland, some here in labrador sum up in this
65:39 , there's also a bunch of western etcetera. So I'm sorry.
65:45 Yeah. So this is absolute oldest forms found anywhere on earth. Now
65:54 don't have sedimentary basins, we don't cortana bases that are that old.
66:00 um, all the chronic basis that have on earth, they are located
66:06 , on crust that is between one four billion years old. So it's
66:13 at the oldest course of the Right? So keep that in
66:18 So the basis are old and they located on very old continent. Now
66:24 this map in the back of your and I'm just gonna show you one
66:29 map and that's this one here. this map you may know, you
66:33 recognize from one of your undergrad introduction geology or So. So what
66:37 see here is a map of the and the continents are colored by age
66:43 the crust. So the age of , of course varies from place to
66:47 . Right? We have places where continent of course is very young and
66:51 have places where the continent of course very old. Now, if you
66:54 at this map, we find the cursed in these pink colored areas that
67:01 called chutes and then close to that in age are these grayish colored areas
67:08 are called platforms or stable platforms. the stable platforms consist of very old
67:16 in which layers of usually flat, laying, very old sediments coffer that
67:24 oldest crust. So we see those regions, all the scores of the
67:31 here in the United States, here North America, Here in South America
67:37 is almost completely very old. Eastern of europe are very old and here
67:44 already mentioned it, the westernmost part Australia. But actually all of Australia
67:49 very old. It's very old core in India. And then also when
67:55 look at this map, you see regions on earth that are much
68:00 Right? The entire western part of America is young. Young means we
68:06 um new crist forming. It means had a lot of tectonic activity.
68:11 Rocky Mountains, the basin and range in South America. Here you have
68:17 endless mountains, the endless forming in last 100 million years in europe.
68:22 course, you have the alps and mediterranean, the Himalayas. Those are
68:26 younger areas where there has been young and tectonic activity on earth and young
68:34 . So these chronic basins, we find on these places where the crystal
68:40 on earth. So you don't find basins in the oceans and you don't
68:45 them anywhere. We have younger christians , they're they're they're marking old
68:51 the oldest cursed on earth. That's they are. All right, let's
69:00 about a couple of characteristics of these tonic basins. So what I'm gonna
69:05 now and um it's very simple. gonna give you a map view of
69:11 of them and that one chronic basin called the michigan basin, michigan
69:23 This is what it looks like. if you look at it from a
69:27 field, you see in the old rocks that are old rocks that
69:33 of Jurassic age and then almost concentric around that you find older and older
69:43 . So here you find rocks that Pennsylvanian in age year. You find
69:50 that are Mississippian in age. And you find rocks that are Devonian in
70:01 . Now, if you look at map view of this basin, you
70:04 it is awful in shape and we the oldest rocks at the center.
70:15 we're now gonna sketch a cross section this basin. So let's make the
70:22 section go east west, right through center. This is what the cross
70:32 looks like. So here's west, east, this is earth surface and
70:40 we're gonna sketch the subsurface. That's underneath. Here we find a grenade
70:57 . So those are crystal rocks, crystal rocks you find here, those
71:06 sediments. And then surrounding that, Pennsylvanian settlements below it below it,
71:15 Mississippian settlements and here the Devonian Now let's talk about size. Such
71:28 platonic basin can easily be 800 km so in diameter. And when you
71:41 at this vertical transact, you may , oh, that's that looks like
71:45 very simple basin. Well, these are in fact simple. So they
71:49 not heavily deformed. And sometimes we that their saucer shaped, soldier shaped
72:04 . Now, when you look at sedimentary layers that have filled in this
72:09 over time, they're actually fairly These sediments, they were deposited close
72:17 sea level, usually just below too to sea level. So um um
72:25 environments that these chronic basins formed in usually shallow water most of the time
72:39 not sea water, it is actually we call terrestrial, so continental or
72:48 something like an inland sea and more inland seas in the next hour.
72:54 this is not a real ocean right? They were never in that
72:58 could have been in a shallow a large area where the continent was
73:04 for example, but the water depth never deep. So it was,
73:09 know, 50 m 100 m, like that, not kilometers of
73:14 So mainly shallow water or terrestrial. what the sediments are telling us.
73:20 when we look at the sediments in , it is clear that these
73:26 they did not come from mountain So these um platonic basins, they
73:32 not not directly surrounded by mountain These sediments when you look at
73:39 they're like old sediments. So they been transported a long distance from a
73:45 range that may have been far Yeah, so they're really these these
73:55 there, the the final dump place the sediments. So the sediments formed
74:01 a far away mountain range, then sediments were transported maybe by rivers and
74:07 into the basin. By the time the sediments entered the basin, you
74:12 , the grains were small, it clear that they had travel a long
74:16 etcetera. So we know that these um that these um Chris tronic basins
74:24 not, it was not that they a basin within a mountain range or
74:28 that wasn't the case. So what think is that the topography surrounding the
74:34 was was fairly long, nothing Now there's something else going on.
74:45 what we also know when we look these sediments, we don't find sediments
74:50 these basins, that indicates that At one point in time, there
74:55 a lot of accommodation space, a depression for sediments, but there were
75:00 enough sediments to fill up that There was, you know, a
75:03 water layer. These basins, there always what we call kind of filled
75:09 with sediments there never under fields. in under field sedimentary basin would
75:16 for example, Death Valley in California the dead sea in Israel. So
75:23 is a basin that has a very depression could be filled with sediments but
75:28 isn't filled with sediments that would be under field basin. And we're gonna
75:33 another example of an under field basin . So this basin, these
75:39 they're always filled with sediments. You really see a gigantic deep depression,
75:44 like that. Now, furthermore, we look at these vertical transect of
75:49 earth basins, we don't see any information. Maybe there's some folding of
75:55 sedimentary layers, but there's certainly not deep grab ins that you would associate
76:02 the rift zone. There may be minor grabbing, but nothing spectacular.
76:12 questions so far. No, Okay, now, the depths,
76:21 sickness of that sediment power varies from to basin. I'm gonna talk about
76:27 later. So now we're we have idea of the, you know,
76:31 dimension the lateral dimensions of these basins of kilometers. They're big.
76:38 so what I have here is a link, a youtube link to a
76:44 tectonic um cycle. And I want show it to you to make you
76:52 of what all happens on earth when platonic basins are already there.
76:57 I'm gonna go back quickly to this that we started out with and then
77:03 gonna look at the basins that are blue or yellow. So when that
77:10 of plate tectonics is gonna play these that are blue or yellow in
77:16 They were already there. They were there in case of the blue ones
77:22 they started to form at that time case of the yellow ones. So
77:26 focus on the basis in North So that's where the animation will focus
77:32 . So these these basins started to at the moment that this animation that
77:37 found on Youtube starts. And then we're gonna do is we're gonna look
77:42 that youtube video if I get it work its last six minutes or
77:47 And then while we look at it we watch that video, we focus
77:51 this area in North America. Just see what's going on with these basins
77:57 the world with plate tectonics while these are already there. Okay, they're
78:02 for me. So, let me if I can get this to
78:05 Sometimes it works. Sometimes it And it comes with the sounds I
78:11 to it last night. And um actually has music. So the person
78:19 made it put music behind it. don't know if you can hear it
78:22 it will come up the sounds. we're starting 540 million years ago.
78:29 your music. Sorry about that. don't know how to turn it off
78:33 we're focusing. I don't can you my cursor? We can't see
78:38 I can't see the video. Okay I'm gonna stop it. No let's
78:43 go. So towards the left side can see north America on its
78:48 It's that island on the left side the ocean. We see it we
78:52 we only see the link. It has your your title side there.
79:01 about we do the following. Um about you open up your your no
79:11 gonna play in the power in the . I don't think so.
79:17 Um If it was I don't yeah don't know if it will I don't
79:22 if you can create a hyperlink on pdf. Mhm. But we should
79:27 should be able to maybe copy that paste it into. Let me see
79:31 we can do that. Okay. just tell us the name of
79:35 We can find it on Youtube and it here. You can play that
79:40 own. We can what's it called Youtube. Um I need to click
79:47 it in order to see it so me do that quickly. Okay and
79:55 it's gonna start for me and I'm copy the link to you. I
80:00 have to link what's the name of ? I mean it will find it
80:04 fast. What's what's the name of thing? Yeah it's something like plate
80:13 . Um And you can just copy link in the chat of the zoom
80:17 that we can click oh yeah there go. Just put it in the
80:25 . Okay. Yeah, it's working me. Okay. I'm complaint here
80:44 well. You have running. it's working. So on the left
81:08 um is this like island with the blerp in it? And that's north
81:15 on its sides. Do you recognize ? So that North America on its
81:23 at this point in time 500 million ago, those basins start to form
81:30 then see what they undergo. They . Sometimes they're flooded when they're brown
81:35 green color there above sea level. they're below sea level. And then
81:40 like plates are colliding and breaking up those basins are. There is the
81:59 when the african played, the african comes up from um the south and
82:08 one point in time do you see ? Yeah, it's just forming
82:12 I see that now. Yeah, that's Llorente. And then the one
82:20 was coming in from the, from right was Baltika which is like
82:25 And the one on top that's Siberia but you also really nicely see around
82:37 I don't know where you are of in your video or. Okay,
82:44 you see the Caledonian, so the forming very nicely and that is a
82:49 range that once extended from southeastern us the way to northern europe And
83:12 Everything that is green or brown is sea level. Everything that is light
83:18 . That is very shallow water. that is like a lens that is
83:23 with a thin layer of all that be 50 m or so. So
83:27 underwater but not deep water. So roughly 300 to 200 is Panji I
83:38 . And you can see the toughest up on the right after like
83:43 So there's three tests oceans, there's paleo, the miso and neo testes
83:50 and and the ocean all around it called Panther Lhasa. Yes I've been
83:58 just wrote a chapter in my book supercontinent. Saw me this stuff is
84:02 in my head. So there was book finished yet My dreams. I'm
84:23 ahead. I mean I was writing into the part one which is all
84:29 know plate tectonics and supercontinent cycles and data and methods and basic classifications and
84:36 like that. But I'm jumping forward I'm just it took me too long
84:42 write that chap because I realized that need to write the main section of
84:47 basin studies part different classes of basin you know how the what gravity magnetic
84:54 look like over those and etcetera And then I can write the introduction
84:59 because I got like a target to to you know what I mean?
85:03 you can focus that chapter then on it needs to have right? Yeah
85:07 I don't need to cover methods that not going to use in the other
85:10 . Because I'm not a I'm not of these grab bag people that
85:15 you know, filter things to I'm not really crazy. But I
85:19 I basically interpret the data pretty much up. But and that's you know
85:25 mean. Anyway. So yeah, think I'm gonna make better progress now
85:30 I'm leaping ahead to do part two then go back and do part
85:37 I hope so. So also in cretaceous around 100 million years, you
85:44 the central part of north America being by a seaway. I don't know
85:50 you're there already. Pretty cool Yeah, it's nice. Huh?
86:22 was just wondering where India is and just came in from the south.
86:27 so good. Yeah, it's Huh? So so these these reconstructions
87:21 all done with uh relative rotation So you can generate a rotation pull
87:30 any two pairs of rigid plates on fear of the earth was just a
87:38 that goes through the center of the and some angle. And then what
87:44 do is people don't worry about this . They just uh tabulate all these
87:51 polls, relative poles between all the plates over time. And then they
88:00 put those in. What was talking earlier is the hot spot reference
88:05 And so once you do that and digitize all your your platonic boundaries.
88:12 you just feed it through this this polar wander uh framework for all the
88:22 relative plate motions. So it is incredibly complicated, but it is also
88:29 of a very simplistic thing to do if you don't mind me interrupting
88:36 No. And it's it's it's pretty . Huh? I think it's it's
88:41 , um, it puts things very in perspective if you know what I
88:50 . So anyway, I mean people work every single one of those,
88:57 , one of those internal reconstructions, hundreds that are in that thing are
89:05 because I can look at parts of world that I work on and I
89:08 this thing is wrong. So, I mean, it's not like this
89:13 this may be kind of a general on a very kind of a tech
89:20 tectonic scale on a global scale, locally everyone's gonna be arm wrestling over
89:27 they think is right and wrong inside . Yeah. And that is that
89:31 right because your eye goes to you know, your favorite regional earth
89:36 you know a lot about. And think, how did he do
89:41 I think that's the that's the danger when people make things global,
89:48 Whether it has to do with sea rise or you know, a topic
89:51 this, everybody's always gonna look at little postal stems that they know a
89:57 about. And yeah, anyways. take a look again here, these
90:05 in North America, they were there the entire time of this animation.
90:13 you could see it right at no in time were they in the deep
90:18 ? They were always in the light to green or the brown. So
90:21 means that they sometimes were uplifted both level and um at other times they
90:29 right at sea level or just below . So that's the situation.
90:34 what we saw is that um during existence there were places where continents
90:41 So, for example, the Caledonian that today are the Appalachians and they
90:45 here in europe. That mountain range furthermore on the right on the western
90:53 of the north american continent. I know if you saw that, but
90:56 points in time, whole islands and arcs collided with North America and grew
91:02 continent on the western side. So other words, this north american continent
91:08 the last 300 or four million sometimes was under compression when it collided
91:14 another continent or with an island are other times it was under extension.
91:20 know, the north atlantic broke up reformed the atlantic ocean in this
91:26 Sometimes there was uplift and sometimes there sub science have been a mental plume
91:30 whatever going by. So all those are recorded in the several very subtle
91:38 in these sedimentary basins, for the Williston basin, you know,
91:43 basins have a saucer shaped, if you look at the sub
91:46 but if you look for example, Williston basin in more detail, you
91:50 that within that saucer shape there's there um sedimentary layers that dome a little
91:59 , they don't and so that domo in the effect of compression. So
92:05 was a little bit of compression felt in the center of the continent.
92:11 and as a result of that, solo anti clients started to form
92:17 Those very subtle structures, they form traps where people, you know,
92:22 to find petroleum and natural gas, example. And so there's there's some
92:28 ones in these very old bases here the central part of the continent where
92:33 first started to drill for oil and . So keep that in the back
92:39 your mind. What's go what has going on in the road since 400
92:44 years since these basins started forming? come back to that in a few
92:53 . Alright, so here is a view of the Michigan basin and Michigan
93:01 is another example of a chronic So, you see here in the
93:06 the Jurassic sediments surrounded in Pennsylvanian age , Mississippian Devonian and then here on
93:13 outside or the eviction sediments. So is the basin, if you if
93:18 look at the cross section through you see that very nice, you
93:23 , gentle dipping of these sedimentary Now, if you look at the
93:29 uh this is the state of michigan Not everything is above water today
93:34 And some other layers have been um . But it gives you an idea
93:39 the size of these basins. So is a vertical transect through the mexican
93:45 . We just talked about the horizontal . So there's hundreds of kilometers that
93:50 talking about here hundreds of kilometers. now let's take a look at the
93:55 scale. So the vertical scale is feet and the lower greenish layer this
94:01 here that is actually the bedrock. those are not sediments. And this
94:06 starts here at the depth of about ft. So just over a kilometer
94:11 at the deepest part of the the bedrock is at the depths of
94:15 13,000 ft. So that is about km depth. Now we also know
94:24 are Cambrian rocks. So this basin been forming for hundreds of millions of
94:33 . So now let's think about let's take maybe this point here in
94:41 sedimentary basin. So say that this is I'm just gonna make up an
94:47 400 million years old sediments that you here for a million years just made
94:54 h And today we find those sediments the depths of 11,000 ft. So
95:01 just below four km. So versatile . This is today, This was
95:14 million years ago. And this here death, this would be a
95:25 This is four km steps 3, 1, 1, 2, 3
95:33 , so Earth services. Yeah, a little bit of topography, so
95:37 this is zero and this is where land surface elevation is today.
95:43 so this is depth. Alright, from a million years ago we're gonna
95:50 which was just around sea level. something like there and today that particular
95:56 was at about 3.5, almost four or something like this. So,
96:03 the course of history this sedimentary layers to where we are now. Now
96:12 don't really know what this line looks . I'm just making it up now
96:18 we're gonna be a little bit more later. So this curve is called
96:25 subsidence curve. And geologists love these curves because they tell you so much
96:35 what's going on. You can imagine in some places you may have very
96:41 subsidence and other basically you may have slow subsidence. You can also imagine
96:47 in the sedimentary basin for some maybe 10 million years, they subside
96:53 and they subside more. So. me get, it's resonating more more
97:02 . So such a science curves are that geologists really like to look at
97:08 . The only thing we know at moment is that this place and this
97:13 . And can I ask a question , is is no longer hasn't been
97:23 sediments since like you said Jurassic Right, correct. Okay,
97:29 So this should go to like shouldn't it? Now? Let's make
97:35 400 till today and then we're going fill in the details later.
97:41 Okay. I'm sorry. No, okay. It's a good observation.
97:45 when I sketched this, I knew one of you was gonna say
97:48 So it's okay. Alright. So know that we are here today and
97:58 know that we must have been there the past. Right? Because sediments
98:02 start to deposit in large areas when when you have a region that is
98:07 . Right? So if you think the Mississippi River in North America,
98:11 transports sediments from half of the continents the gulf of Mexico and the settlements
98:19 they are dumped in the gulf of because it's on the water and that's
98:23 you dump your sediments. And so the river mouth where the Mississippi flows
98:29 the gulf of Mexico which is right sea level, that's where the sedimentation
98:33 . So that's why I'm putting this sea level. But you know,
98:37 you get to the point hopefully Now don't know yet what happened between this
98:44 here and this point there, but are there are clues. So what
98:50 just mentions the oldest sediments, they to be something like 200 million years
98:55 . So that is around like Also, if you would drill a
99:05 in this basin, you may find some sedimentary layers seem to have been
99:12 and if a sedimentary layer is that happens mostly when it's a gulf
99:19 level. So in the continent and there's erosion of the continent.
99:23 And we saw already when we looked this animation that for some periods of
99:29 time this basin has been above sea . It was either brown or green
99:33 color. So we can find that when we drill well. When we
99:39 well, we can we can look the different rock layers in the well
99:44 we can say for example, it like we are missing some rocks
99:49 This must be an un conformity. missing piece of geology. We can
99:54 by looking at the type of we can see where these where these
99:59 were deposited, where they deposited, at sea level, where they deposited
100:03 m steps where they deposited above sea and the flu feel system, a
100:08 system. So that information can we is what we can get out of
100:13 . So, if for the michigan , if we include all that
100:17 we may end up with a subsidence that looks something like this. Um
100:35 other words, there has been Maybe this phase here where subsidence was
100:41 rapids, there have been other maybe this phase here where subsidence was
100:47 , there also may have been faces there was uplift above lift, double
100:52 level and above erosion. Maybe here is a phase of uplift. You
100:57 that this is a phase of uplift we know that that that may have
101:03 if today were drilling. Well, see that are missing rock layers,
101:08 formations. There's a gap in That gap may be present. A
101:13 of rocks of sedimentary rocks that were . So maybe there was uplift and
101:18 around this time. Maybe there was lot of uplift and erosion around this
101:22 . And this is where we end today. So this is called a
101:27 curve. Now the subsidence curves, record two things what it's the tectonic
101:37 . Whatever is going on in geology makes this sedimentary basin. So a
101:43 process or tectonic components and that can continent continent collision during which the continents
101:51 the compression and there's uplift and mountains me or a tectonic process can be
101:57 extension of a continent. Anything like could be a tectonic we call a
102:03 process and subsidence curves have a second in them and that is what we
102:10 the sediment load. And with I mean the following if you have
102:20 sedimentary basin just going to sketch it simply. So here is this is
102:26 the first, right? And then here we have a depression and we
102:30 sediments in here, Those sediments, have a weight, they are whatever
102:38 kg per cube, something like Those are sediments native become sedimentary
102:43 So that is some mosques, they a weight. These sediments, they
102:47 as a load a load on the . So as a result of that
102:55 , what the christians doing, it's subside a little bit further under influence
103:00 that load and then more settlements are in here and it's gonna subside a
103:06 bit further on the influence of the again. So in other words,
103:13 subsidence curve that you see here sketched shows that tectonic process. Again,
103:20 there was compression and some uplift, the atlantic ocean opens and the entire
103:25 was under extension. And was there subsidence and that it combines that with
103:30 sediment load again, when you load cursed with settlements, the crystal subside
103:36 little bit further, you can put sediments in that accommodation space etcetera
103:41 So these two effects together make the curve. Now the subsidence curve for
103:51 the Michigan basin, you may be maybe you think of four km of
103:57 . That's actually pretty good. Well about that this happens over hundreds of
104:04 of years. There was at least millions years of subsidence before we got
104:11 we are today, hundreds of millions years of subsidence. So let's put
104:17 into perspective. So I'm gonna put into perspective now, I'm gonna sketch
104:23 same graph but slightly different now the axis is at the top of the
104:31 and we put subside ear's here. I'm gonna sketch the same graph that
104:39 just sketched. So the past is and the presence is here and now
104:46 gonna look at the subsidence curves. you start in the past maybe here
104:51 then we don't know what what went . Maybe there are phases of uplift
104:55 subsidence, we don't know. And end up some somewhere like here
105:02 So that's that sub science curve that just looked at now we said that
105:06 uh consists of two parts a tectonic and a sediment load part. Now
105:19 have a simple simple way available to to remove the sediments part. And
105:28 tend to do that. They like do that because they can look at
105:32 subsidies that happens as a result of tectonic process only. So next
105:37 I'm gonna explain to you how we do it now. I'm just gonna
105:40 that this is the case. So this subside and scourge of if we
105:47 here the effect of the sediment we end up with a curve and
105:51 just making this up that looks something this. This is the end
105:56 Now, here's the beginning point and something look something like that. This
106:07 we're gonna call tectonic subsidence just to that it's no longer having that effect
106:14 the sediment load on it. We remove the and um this is what
106:21 left with now in the case of Michigan basin. Um if this was
106:26 km this is probably only gonna be kilometers or so. So we now
106:34 up with 2.5 kilometers of subsidence let's just make up some million years
106:43 200 million years. I can tell that's very little for 200 million years
106:51 only have 2.5 kilometers of subsidence or four kilometers of subsidence, that's barely
106:58 . And we can compare that with pull apart basin on the pull apart
107:03 , you easily have four kilometers of in a few million years. So
107:09 to that, this is extremely So what we say is that these
107:14 tonic basins, they undergo slow subsidence almost you could almost call it ultra
107:25 subsidence super slow. Not much happens all those um millions of years.
107:36 , when we look at the tectonic curve, the shape of the curve
107:40 the total subsidence curve. It's not different. You see, it's not
107:44 much, right? It just peters a little bit. It may go
107:48 . It may go up, but about it, There's nothing spectacular going
107:53 , nothing shooting up or shooting So it's basically rather gradual subsidence.
108:01 the other thing that you could say um that characterizes its subsidence. There
108:06 always these periods of uplifts. One shown here, one is shown
108:11 So there's always phases of uplift. phases of uplift. They again,
108:19 correlate to when the continent was under . Yeah, so that is what
108:28 the subsidence of these cra tonic And we'll come back later to this
108:33 weekend and the weekend after any questions this. Um Yeah, that that
108:39 a lot of sense. Um One I had was that I was gonna
108:45 if the process of removing subsidence from load. Um Does that relate at
108:54 to back stripping? It is back . I wasn't sure if if I
109:03 I didn't want I didn't want to the word but I'm very I'm very
109:08 that you picked up on it. , good. And that's a that's
109:12 very simple method today. We like do it, you know with a
109:16 computer codes. But next weekend I show you you can even do it
109:19 hand. It's a lot of Right? But you could do it
109:21 hand. Um So yeah, so do an example in class.
109:27 So you just mentioned that in the , this is low subsidence? Is
109:33 going to differ for every basin and it's going to like, how can
109:38 say that it's low in this catatonic it might be different in the
109:43 That's an excellent question. Let me if I have more space. Um
109:52 really, but this is an excellent . So what's gonna be the clue
109:56 this course? One of the conclusions that every type of sedimentary basin,
110:02 basin is a type of rift is type, a catatonic basin is a
110:06 . Every type of sedimentary basin has very characteristic subsidence curve. And so
110:14 subsidence curve for all catatonic basins, can just sketch it here in a
110:18 corner first onto excess years time from to today, vertical axis is subsidence
110:27 as you see here on the back , it always looks like this always
110:34 matter when subsiding started. It's always like that, It is never
110:41 it is never um this, you what I mean? It always has
110:48 like just slow just on going a bit, not much is happening going
110:55 . It's always that. And so means that at the end of this
111:01 , I can give you a subsidence For example, this one and you
111:09 know that this must come from a that was drilled in a creek tonic
111:15 . I can give you a different skirt, maybe one that looks like
111:21 and by the end of this you would know that this comes from
111:24 drifted continent margin or in the case a foreign land basin subsidence curves look
111:31 that. It's never any anything So at the end of this
111:37 you will know this, this type basin is formed there. This is
111:41 it subsides, this is what it like, it's always the same.
111:46 that is really helpful. So, know, one time in your career
111:50 may be getting well data and you get to answer the question, what
111:55 of basin are we actually looking at ? You, you create such a
112:00 science curve, you plot it and know, but what sometimes happens is
112:06 case is that a place um let's if there's a good example here.
112:16 is actually sometimes a place may start as one type of basin and lady
112:23 a different type of basin. So can imagine here in Oklahoma um it
112:30 have started out as a chronic but then at a later point in
112:35 maybe this became a foreland basin for . So sometimes you see that there
112:39 an earlier basin and then 100 million later there's a new type of
112:43 You can see that but those these that we just sketched, they never
112:51 . Um so it's very cool. you. You're so welcome. Now
112:58 one thing, I actually was misleading another the following. So I said
113:04 , Okay, four kilometer of That's how deeper on the michigan
113:08 You remove the effect of the sediment an hour or 2.5 kilometers maybe
113:13 So, in real life, in in platonic basis, if you remove
113:19 effect of the sediment load, it not even be 2.5 kilometers, maybe
113:23 only end up somewhere here. It be even like only one km of
113:31 in two million years. So maybe less deep. If you would never
113:36 any sediments, that's how deep it be. So, if you look
113:39 these curves, this one, what call tectonic sub science without the effect
113:44 sediments. That is if you would have had the tectonic process and you
113:48 the depression or the accommodation space. you then add the effect of the
113:53 , the sediment load, that's when basing becomes deeper and deeper quickly.
113:58 then you can end up at this color if you see that.
114:04 all right, let's take a look this figure and then we can have
114:11 short break. So here, I've this is from a paper that I
114:17 actually send to you tonight or sometime week. Years shown subsidence curves of
114:26 tonic basins here. They're called intercontinental . It's again another name for the
114:32 type of basin from about eight difference these basins on earth. So what
114:38 you see the version two accesses Time you see that million years ago
114:44 here presence today, vertical access is or subsidence usually shown in kilometers
114:53 shown in kilometers Now, these are types of atomic basins but follow some
115:00 these curves. Let's follow curve number . It starts here around 400 540
115:06 years ago subsides tiny amounts a little more than you see here, a
115:13 flat part and I'll come back to in a second, a little bit
115:17 . Science fled a little bit more in there stopped. Let's take another
115:23 , number six here. This basin forming about 250 million years ago.
115:30 there was a phase of fairly rapid . You see that. And then
115:34 then it has been going really, slow. Let's take another example.
115:41 number one here started as around 550 years ago, fairly rapid for a
115:49 and then it just petered out and slow, slow, slow,
115:52 slow. So you see the right? Nothing spectacular. Slow subside
115:58 nothing's particular. I'm going to talk one more curve number seven year.
116:03 it starts around 230 million years Slow subsidence. The face of uplifts
116:09 little bit faster subsided face of uplift face of uplift subsidence face of uplift
116:16 , etcetera. That one really goes and down. It's the paris basin
116:21 europe. So the paris basin in has felt, you know, when
116:25 looked at that animation, you saw forming because although those collisions,
116:30 just colliding at everything. So, the course of millions of years,
116:34 continent sometimes was uplifted and that is is recorded here. Now. Also
116:41 here, you may have noticed this is what's called sea floor subsidence when
116:48 floor is created at the mid ocean , which it's um you know,
116:55 cools down over time and it's cooling over time of the sea floor causes
117:00 subsidence. That subsidence is considered to slow. And it's shown in this
117:07 here. So, these authors plotted curve. So, you could could
117:12 it with the subsidence rates of these basins. So, you see,
117:19 very slow, you know, sea subsidence is supposed to be slow um
117:27 to sea floor subsidence, this is even slower. So, super slow
117:33 on. And we're going to look other subsidence curves on this plops,
117:37 pull apart basin subsidence curve would basically almost a straight line down like
117:42 or maybe even deeper than that. , compared to all other basins on
117:47 , these inter continental basins or platonic , they're super slow. Okay,
117:54 about this before we have a No. So what we're gonna do
117:59 have something like a 10 minute break 102 and then I'm gonna finish these
118:04 basins and then we're gonna move on talking about the strength of the little
118:12 . Okay, I'm gonna stop sharing and we can have our little break
118:21 perfect alright, so you can see screen, right? So we're gonna
118:25 at some examples of Cortona basis. what you see here is a close
118:30 of southern Africa, south central I would say. And this reaching
118:39 , you see it's a depression, is the Congo Basin, this is
118:44 some geologists considered to be an active basin. So you can see the
118:51 , right, it's around shape, is slightly lower topography, the rivers
118:56 flowing towards um this depression And if look at the dimensions, so this
119:04 10° north, this is the So this is about what, 2000
119:12 or so. So that gives you idea of what you're looking at
119:15 So these are very large areas often or roundish in shape. Here's another
119:23 from Africa, this is the chat . And so the chad basin also
119:27 slight surface depression as you can see . Um it is not just like
119:35 the Congo basin, it's not surrounded by high mountains or so. So
119:41 , these sediments that fill up these are not, you know, and
119:45 coming from landslides from the mountains, undergone a much longer um you
119:51 path of transport. Same child And also here, you can see
119:55 shape, right, somewhat circular in . Another example, the West Siberia
120:00 . So we're looking here at Northern Siberia here at the Euro Mountains to
120:06 to orient yourself. Um and this would be the West Siberian Basin which
120:13 hopefully recognize here is um in the the oldest core of the West Siberian
120:22 . There are some fine rift nothing major but some minor rifting that
120:32 in the earliest phase of the formation this, this platonic basin. And
120:36 see that in many other chronic basins well. So that is not
120:42 Alright, so let's summarize these characteristics atomic basins. So they're usually over
120:52 in in a a map map. and their souls are shaped if you
120:58 at them in a vertical transect. there's a saucer shape we noted that
121:05 writes the large, well maybe 502,000 or so in diameter And they're not
121:15 deep. Um so have several They can be easily before kilometers deep
121:22 so they're not not 12 km so deep but not extremely deep.
121:29 the other thing that we saw is these cra tonic basins, they
121:34 So they're forming for hundreds of millions years and we find them only on
121:48 creek tonic, the oldest part of continents tectonic regions, but the oldest
121:54 is huge. Um Those parts of continents, that's where we find them
121:59 in oceanic little sphere, never in portions of the continent. So with
122:06 characteristics in the back of our how can we explain their information?
122:12 , these basins, the interesting thing , is that we actually don't know
122:17 they form. So there's a few in in the literature of people,
122:22 say now we know it, they like this, but then if you
122:26 at another critical invasion, it could have worked like that. So it's
122:30 a mystery how they form. So are they forms? There's several theories
122:36 in the literature and I'm going to discuss all of them. So,
122:41 are the four. The first one called a sleep model for atomic
122:46 And sleep here is the name of scientist from stanford who came up with
122:51 model. The 2nd model is gonna it dynamic silence. The 3rd model
122:59 subsidence of both anomalies, density, sphere or mental. And the first
123:05 is economy called slow rifting. And model here, the fourth wall has
123:11 most fence doesn't mean it's true, it seems to work for quite a
123:17 cra tonic basins. So I'm going first start with the first explanation sleep
123:23 for chronic basis. Now when you at the center or when you look
123:32 a couple more models, like some suggest like phase changes in the,
123:40 this fair and weird stuff like And uh thermal anomalies phase change,
123:49 one is gonna be part of the third one and the thermal anomaly
123:55 going to discuss. Um, and , so every year when I teach
124:03 class, I asked the students, you come up with another one or
124:08 better model? And most years students up with something that's actually better a
124:14 of all this existing, but what's , um, that is how,
124:18 know, but whenever I see something this, whether it's like half a
124:24 models suggested for something, I always nobody knows anything but rifting suggested there's
124:33 of tectonics going on there. And not really the, I mean,
124:38 know that there's people that say but I mean, I personally,
124:43 just don't like it because I I think a lot of these things
124:46 don't see any evidence of, you , I mean, there's an older
124:50 beneath the michigan basin, but that older rift is like pre Grenville
124:56 the Michigan basin is a paleozoic So, you know, anyways,
125:00 sorry to interrupt. No, so a really good point. So this
125:05 every year, most of the students don't like anything most, any
125:10 these and it's also really good and think it's really good to bring this
125:15 deal. So when I go through list, um, feel free to
125:20 super critical because I, I cannot start to say about how I don't
125:26 these explanations. I do have assault about these basins, that is very
125:32 . So I'll mention it in the but we're not going to put it
125:35 because I never published it but they , I'm interested to hear Europeans.
125:39 let's let's walk through these and you just be completely honest with me if
125:46 don't like it. Okay, let's . The first one is the sleep
125:50 for a platonic basis. So This person is called norm sleep and
125:55 was a fantastic scientist at Stanford University you may know him alright. Oh
126:09 , yeah, yeah, yeah, , yeah. So this this person
126:14 , he's truly a brilliant earth So he suggested this this model many
126:21 ago before we had much more evidence that that have come true. But
126:27 added to the list Anyway, so model for Cortona basin. So this
126:31 is based on mental clones. So looking here at six figures that show
126:38 transact through um the earth schematically showing colors mantle plumes. So what you're
126:46 at here, this is the outside the earth, right? This is
126:49 surface of the earth. This here the core mantle boundary. So everything
126:57 that bluish sphere is the core of earth. And so everything that's open
127:03 the mental these things here are mental . You see that these are mental
127:10 that are sticking up and you see they are very different in shape and
127:14 . Some seem to be emerging, seem to be dying out fading
127:20 Some seem to be clustered very forming large zones of uplift anyways, they
127:26 all kinds of different forms and shapes this is how many scientists thinks Earth
127:32 , what earth mental looks like and these mental proofs look like in real
127:37 . So plumes coming up consisting of material moving up to, you
127:43 moving into the Mental towards the Now, this is a computer animation
127:50 about the same situation. What you here, these colors are again,
127:56 mantle, the red sphere in both , is the core of the
128:01 So what you're looking at it, blue colors towards the left and yellow
128:05 towards the right is what we call confection. The yellow colors towards the
128:10 show everything that's hot and coming up blue colors towards the left, show
128:15 that's cold that's coming down. So things going down in a mental are
128:21 sub ducting oceanic slaps. What stuff up in a mental is usually mantle
128:27 . So that is shown towards the Now. What did we see
128:32 Already a little bit if you have plume like this one coming up moving
128:38 towards the surface, what it's gonna , it's gonna cause this dynamic topography
128:43 dynamic uplift of the surface and dynamic of the surface is very long wavelengths
128:51 1000 km or so. And the of that dynamic uplift is not much
129:00 of meters, maybe a kilometer. nothing spectacular. And you can imagine
129:07 a distance of 1000 kilometers, 100 or even a kilometer of uplift
129:13 You know, it's even very hard see that, but that is what
129:17 mental plumes do. Now. What sleep suggest, norm sleep? He
129:23 , hey, if you have domo above such a mental plume this
129:30 these mental plums, they live for long time, right? Tens of
129:34 of years. So this will start erode and you're gonna erode apart.
129:42 know, that took part of the uplift. Now, the next step
129:47 that mantle plume dies out. You longer have dynamic uplift. This is
129:51 it's gonna look like. Normal uplift it other side of the dome.
129:59 , if that mental plume dies out the dynamic topography completely disappears the
130:04 So too will be this for its , a depression where the dog used
130:11 be and the material that has now eroded earth surface. You see
130:15 So here, now you have a large area. Remember that at wavelengths
130:20 1000 kilometers or so that is now depression and that can be filled in
130:24 sediments. So this was an idea norm sleep has to explain this cra
130:30 bases. Sleep model. I'm gonna this, this and this. We
130:38 talk about this another time. All , I do need to go back
130:46 I need to finish this sleep So, what this does this model
130:51 ? It predicts that you have a that is large, Probably awful in
130:57 . Right? Because these mental plumes up, it's not a square,
131:00 not an elongated region, it's rather in shape. The dimension should be
131:06 large, maybe 1000 km or This can be filled in with
131:12 This will be a slow process. ? Mantle plume that comes up,
131:18 eroded. Then the whole thing subsides . You would expect us to be
131:22 slow process. So, what would model explain? It would explain probably
131:27 dimensions of Kryptonian basins? It would maybe the saucer shape because there's nothing
131:35 going on. So, saucer shaped . Um, so, to explain
131:42 whole shape of the basin, let's what else would it would explain?
131:48 , maybe a long phase of slow . So, the subsidence part of
131:53 story, it would explain why why you look at these colonial basins,
131:59 never anything spectacular going on. there's not a major risk basin or
132:03 else. It would explain that because much happens. And that's it.
132:10 , why don't people like this model . If a mental plume came up
132:16 bringing that hot material towards the What would you expect? Volcanism and
132:23 of these catatonic basins are correct. by a lot of folks at no
132:28 in their development. Two, if had such a large dome, remember
132:33 was a dome presence here that was completely eroded. These settlements must have
132:38 somewhere. So these sediments, you , you're talking about an area 1000
132:45 wide, maybe 500 m high. a huge pile of sediments. The
132:50 have never been found. So, this was true, where are
132:56 Um we can't find them back. in other ways, although this might
133:04 might be a nice model in our . There has been no evidence for
133:08 . So, it's no longer seriously as an explanation for um cra tonic
133:16 . Any questions about this model? right, then, let's move
133:25 The second explanation was not the second on the list. I noticed.
133:31 it was the second one on the . Let's just see if we can
133:34 to the order. Hear o dynamic , I will I will do this
133:43 now and then we go to the one, Let's talk about dynamic
133:47 So, we just had a sleep was dynamic uplift and then erosion.
133:52 , That was the sleep model. second model is So what related?
133:57 called dynamic subsidence. What's going We saw earlier today that if you
134:02 , you know, if you have mental flow in the mental so downward
134:10 or downward slow in the mantle, above that area, you may have
134:17 topography causing a depression, just accelerating here. But you get the point
134:23 , So sleep was talking about the coming up and you've uplift here,
134:28 would have mental flow going down and . So, some people have suggested
134:35 if this would happen, you you could fill up this space with
134:42 . So what would this explain this confection? Mental flow that happens a
134:48 scale. So you would expect this have a wavelength of us, maybe
134:52 km or so. So the diameter be correct. You would expect the
134:58 to be slow because mental confection is . Nothing happens fast in the
135:05 So, you would probably have slow term subsidence the shape of the
135:12 Well, mental confection, it isn't line or something like that.
135:17 you probably would expect an awful So that means that the shape predicted
135:23 this will be fairly similar as Now this um um this particular explanation
135:34 cra tonic basins, there are there's not much support for it because
135:39 no evidence for it. So, works really well in theory, we
135:43 make it work. Um but there's evidence for it and that is why
135:47 don't really like it, but but , I mean, dynamic topography amplitudes
135:54 only a few 100 m and you to have that initial kilometer of,
136:00 basin fill before you get the feedback the thing filling up, don't
136:06 Yeah. So, what you could is that there was something that caused
136:11 little bit of a depression here, there wasn't all the rift base and
136:15 with settlements in here that was followed downward flow, something like that.
136:21 So there's, there's, you you you can you can come up
136:25 arguments to make it work, but , there's no evidence for it.
136:31 , what are you gonna do? next model that has been suggested in
136:40 literature is subsidence above enormously see dense sphere just gonna go forward and we're
136:47 go to that one here, it . Now the outside of the
136:54 the little sphere has a certain We talked about it yesterday, the
136:58 , the density of 20 720 800 per cube. The mental little sphere
137:02 of 3300 kg per cube. Um have argued that in places, the
137:10 layer of the little sphere may be than in other places. So,
137:14 could this be the case? This be the case if maybe um there
137:21 mental little sphere was deeper at some in time and therefore um it's the
137:28 that are in the rocks underwent what call a phase transition. A phase
137:36 basically means that minerals that could normally be packed like this. If this
137:42 a crystal of a mineral, what say is that at large depths or
137:49 are very high. Um these they are no longer stable, they're
137:53 be taxed more efficiently. Basically we it a phase transition. And the
137:58 mineral may look something like this. basically packed into a smaller value,
138:10 called a phase transition. Now you I mention that when such a phase
138:15 happens that the density is going to this year is a dancer than this
138:23 . So denser material, high density would add an extra mass to the
138:29 sphere. So here's such an extra is shown. So so to face
138:35 , that's 11 way to create an mass. People have also thought or
138:40 if there's a mental plume coming up there's a lot of melting of the
138:46 and some of these modern rock they reach the surface rights and results
138:51 focus on is um the stuff that's behind is denser rock. So that
138:56 also cause a denser rock here we that a dense magmatic residual, like
139:02 denser magma chamber. So anyway, denser. So you can imagine that
139:08 you have a high density mass in little sphere in the mental portion of
139:13 little sphere, what it's gonna it's gonna deflect the service above
139:19 You see that and it's gonna cause depression that can be filled up with
139:24 that is shown in the figure here the lower left. Such a depression
139:29 such a high density mass now. there's scientists who have suggested that this
139:34 be an explanation for economic basis. can imagine that the wavelength is about
139:40 . You can imagine that the shape the basin will be about right because
139:45 again very slow process, rights, of subsidence, long term is about
139:52 . Um, so you can make work again. However, also for
139:58 explanation, there is no evidence questions this explanation. No, it looks
140:10 we can make anything work. this model was the fact when people
140:16 to look at the Congo Basin. the Congo Basin. Remember that's the
140:20 tonic basin here in south central the Congo Basin. So, when
140:27 looked at the mental below the Congo , it looked like there was indication
140:34 the Mental here may have higher And that is actually shown in the
140:38 below here. You may have seen figure like this before. The vertical
140:43 here is depths and horizontal access is and this is a vertical transact here
140:51 africa through the Congo basin. These here show what we call seismic wave
141:05 basically how fast seismic wave travels through . Now, seismic waves travel faster
141:13 rocks that are fast that are quote um yeah, let's let's talk about
141:24 about cold Besides my grades travel slower rocks, that's our warmth or even
141:34 molten. Now in this panel here the bottom, everything that's orange and
141:41 is slow. Everything that's bluish is . Now you look here below the
141:47 basin and you can see here there's big blue blurb. So big blue
141:54 . People think, okay, fast . So maybe the mental here is
142:00 cold cold rocks or a denser than rocks. So worm rocks are less
142:15 so. People thought, OK, way, philosophies, blue blocks called
142:21 material denser material. Maybe this is example of a place where you would
142:27 done some material in your upper mental down the whole plate there, causing
142:33 sub science, that's basically the only we have on earth for that.
142:39 model could work in this specific Questions about this. All right,
142:54 then, the last explanation for chronic is has has most fans amongst um
143:03 Earth scientists. It doesn't mean that right. Just is most popular.
143:08 , this explanation says that these basins formed by slow extension, slow extension
143:14 the little sphere. What do we ? Let me see if I have
143:19 empty slide here. I have an slide here. Just gonna call it
143:23 extension. Now, we started out with Earth cursed right underneath. You
143:30 the mojo. And underneath that you the mental portion of the little sphere
143:40 nobody needs that. We have the And then we talked to the beginning
143:48 the morning about that this little sphere for boundary here is an isil therm
143:54 or so. Now imagine that you're extend or stretch. Oops. I
144:04 I just turned it off my Oh so my pan I just turned
144:14 pan off and I don't know how turn it back on. Its magnetic
144:20 . Uh Let me just oh now loading sticky notes. I didn't want
144:28 do that um taken out. I'm maybe I should drop it again.
144:39 have an idea if you have such magnetic pen, how you can turn
144:43 on again. That's um just gonna go out of here and see if
144:52 can somehow make it respond again. I'll do that during lunch time and
144:58 just quickly go on here. I'm stop sharing. So free to take
145:07 minute break. I'm gonna see how can link the magnetic pan um to
145:15 computer again. Okay. You have suggestion. Oh no I wish I
145:23 . Sorry. So I had it before. Um So I will be
145:33 to find it at least in a break. So I think I'm
146:03 I'm just gonna see if it works . Yeah I'm back. I got
146:09 . You got it. I got about that. So we're back,
146:14 the screen again. Yeah we are . All right, sorry about
146:28 All right, So, we're back the little sphere cruise mojo mental
146:34 Now, when we start stretching or this little sphere, what's gonna
146:40 We're gonna form a rift basin. gonna have normal faulting in the brittle
146:45 crust and um of base informs that will be filled in with sediments maybe
146:52 something like this. The mo hall actually um No, it's saved
147:00 The mobile will start to come up the crust thickens a little bit.
147:04 it looks like this. So that's new mole hole. And then here
147:08 large depths, we also see that little sphere as the boundary is coming
147:14 . Because we stretched the crust, stretch the little sphere, it needs
147:17 thin that sinning is taken up by faults in the upper crust by dr
147:23 information and lower by viscous deformation in mental atmosphere. Now, what's gonna
147:32 next? Say there was some minor , we form a rift grab and
147:37 spectacular. And now extension stops. , when extension stops now, the
147:42 system will come to a halt and that means the following This little sphere
147:50 boundary, that is actually an a therm 1300°C at this point in
147:56 , it is actually at rather shallow below the rift zone. But if
148:01 comes to an end extension comes to end, the system will cool
148:07 Nothing happens anymore. Tectonic lee with down. this here is too
148:13 so it's gonna cool down. And ice affirmed the base of the little
148:17 is gonna come down in the course time. Would that make sense?
148:26 . When this comes down, this ? When this this this isil
148:31 the 1300° isil therm Goes down and found at larger depth cans. The
148:38 the following is going to happen to rocks. These rocks used to be
148:54 or 1100 degrees Celsius, the rocks cooling down. What's gonna happen with
148:59 density of rocks that are cooling City increases. Yeah, the density
149:11 increases and here the density increases So, in other words, these
149:20 here has during the schooling phase their will increase. It will increase to
149:29 than it was when the whole system fought. Now, we've just seen
149:34 higher density rocks here, What's gonna ? This surface is gonna subside a
149:40 bit, not particularly, but a bit over time. And the surface
149:47 subsides a little bit over time, create some accommodation space rights that can
149:51 filled in with sediments and you can that you start to form a slow
149:57 sedimentary basin there. So, that the explanation that is associated with slow
150:03 . So, when people say minor or slow rifting explains atomic basins what
150:09 mean? As first some kind of zone formed, there wasn't anything spectacular
150:14 rifting, but as a result of minor rifting, you had some heating
150:19 of the rocks here. Now, next step, what would happen is
150:23 the system cools down these rocks cool , the density increases and as a
150:28 of that, you have a little of subsidence at the surface and you
150:32 form a cra tonic basin. That's thought. Now, this would explain
150:38 the long duration of subsidence. It explain approximately the shape right of these
150:44 basins. It would also explain that of these platonic basins and they would
150:49 mentioned it a few minutes ago. you know, when we look at
150:53 patients at depths, some of them these old rift structures underneath them.
151:01 that is the fourth explanation for the of crotona base. So let's go
151:05 quickly and then we have time for and discussions and I can also give
151:13 maybe a different idea. So, roughly four models out there in the
151:20 . Um The sleep model was a that said mental uplift erosion subsidence,
151:26 dynamic subsidence model that said, you down going mental flow above that you
151:32 a big depression is filled in with , you form a platonic basin.
151:37 third explanation of subsidence above an ominously little sphere. So maybe there has
151:43 some kind of process that increase the of the little sphere in a certain
151:48 . And as a result of everything is going to subside. And
151:52 fourth explanation is by slow or minor . And that was the last one
151:57 we did that we just discussed any or questions about any of these
152:07 May I jump in or I don't . Okay, I hope you're the
152:13 students don't remember. Don't mind I have a lot. I
152:17 I've looked a lot of a lot these bases and I think that if
152:22 saying the consensus is the slow I still think there's consensus. But
152:28 slow rifting seems to be most I think that's just nutty because
152:37 if you're gonna have slow rifting then gonna have slow convergence somewhere. Where
152:42 that? Yeah, let's move into uh deal. So if you there's
152:49 paper by armitage and Allen and that actually shows that slow rifting that results
152:59 what we just sketched this, singing little bit of singing of the mental
153:06 , that actually this Sinning is not and the cooling is so fast that
153:12 could never form a catatonic basin. they show to their own models that
153:18 actually doesn't work. I mean you know, the thing about these
153:24 is they're very simple geometrically they're just bowls. But the problem why is
153:31 these methods is because you have to some initial and they reckon a kilometer
153:37 accumulated sediments before you start to get feedback where it's now it's subsiding and
153:44 it's accumulating more sediments on top of . But you've got to have that
153:48 kilometer. And these all these models an attempt to capture that. That's
153:53 idea as far as I understand And but I mean if you're gonna
153:59 plate tectonics, that is, you , horizontal lateral motion of little
154:06 then if you're gonna extend it, you have to accommodate that with some
154:11 sort of, you know, compression I think. And there is um
154:19 is also in the basin analysis book the third edition, right, a
154:24 um that I think you have a of. So if you if you
154:31 at that that book, so the , they have been looking at that
154:37 there, you have the third edition the second. Okay, so when
154:47 look at that third edition, they up with some um they try to
154:52 the formation of these chronic basins to large plate tectonic events. So,
155:01 continent collision or so, and that isn't there? So, um what
155:08 what you talk about, you it needs very slow extension just means
155:12 else. You need very slow what . And um so they have not
155:18 able to find that. So I'm , they've not been able to find
155:26 . So deal in europe impression what cause, what do you think causes
155:32 first phase of subsidence that puts the there and then get the whole thing
155:38 . So I think what I would is I would, I mean I
155:43 and I could probably do this, could I could look at subsidence rates
155:48 some joyed anomalies, you know, and and and see if that gives
155:54 some joy there, you know, I haven't done that, but I
155:59 and then I guess, I don't if I guess someone's probably done
156:04 but I would look at maybe there's thermal anomalies. I mean, I
156:08 if there's a thermal anomaly, you , um in in the Congo
156:14 you know, if there's a and because you got because you have to
156:18 it, you know, you have do the thermal anomaly at the time
156:20 basin farm, which is challenging. I mean, I guess you can
156:25 it with, you know better night or whatever. But but I think
156:31 uh yeah, I mean to me anomalies or geode anomalies just seems like
156:38 they're not systematic. There they I mean, I don't have a
156:44 thinking it's, you know, some sphere IQ stuff going on. But
156:50 the idea because I don't think it's tectonics, I think it's just
156:54 I mean and bring one more point in this discussion. And that
157:02 you know, when we sketched their curves right that time and that's,
157:09 when we looked at those curves, often go through some uplift subsidence is
157:15 minor most of the time that there's tectonics involved, but there are phases
157:20 uplift. And the interesting thing is after those phases of uplift and
157:26 These basins continue to subside. You that the uplift phase may have been
157:31 and followed by another 80 million years subsidence and may have been another uplift
157:37 . So, somehow what's going there doesn't end with minor uplift But
157:45 , you know, there they the growth of these things is on
157:49 supercontinent cycle. Okay, so super , you know, from from closure
157:56 opening the closure, that that cycle on the order of 300 million
158:01 So, you know, maybe it's to to the, you know,
158:06 avalanches and super plumes and all that of stuff. But I mean,
158:11 that's the sort of secular variation That things occur over, you know,
158:17 that sort of 300, that's a cycle, It's also another time.
158:25 it takes 200 million years to 300 years to erode a mountain.
158:33 remember that the sediments for these bass , we said that earlier on they
158:37 from far away. These basins are , it's not that you have a
158:41 surrounded by mountain range right? There's far fields um mountain range for example
158:48 Appalachian mountains. Those mountains provided the for many of the platonic basins in
158:56 America. So you could also see as a sediment source problem and there's
159:03 continuous enormous source of sediments when a range starts to erode and eventually completely
159:10 . That's the same time scale. . So yeah. I mean I
159:17 there's things to chase I imagine. mean I'm gonna be this is the
159:21 chapter I'm gonna write by the I've just been doing a bunch of
159:25 searching but um I I think that there's a lot of things to chase
159:33 that I think make more sense than plate tectonics. You know, horizontal
159:40 of with the spirit plates two. think that is just I mean it's
159:47 it's like yeah you would think that , it's like your first guest not
159:52 last guest to me. I mean know I don't know I just agree
159:57 you. And so when I look the subsidence curves we can look at
160:02 again. Yeah. That's very I like that figure with all those
160:09 from Allen and Allen. Is it subsides curse. Yeah, this
160:13 Sorry about that. Yeah, this . So we're going to see much
160:20 from their paper. So This the curves especially this one, # four
160:30 . This tells you if you think , you know, next weekend we're
160:34 talk about back stripping and how you these curves. What you will see
160:39 that if this side so slowly it's slow as this part of this
160:46 right? Basically it means there's no going on. Um So there is
160:54 technology here. Yeah. Yeah. . Yeah. Yeah. That's a
160:58 point. Yeah. There's no And if you look at the error
161:03 introduced by the back stripping methods, curves except for something like this and
161:08 like this. This you could basically is completely flat. It's it's the
161:14 margin in the back stripping methods creates slope like this. So you could
161:19 this as flat, this as this is already flat. Do you
161:23 what I mean? It's flatter than looks here. And so that means
161:27 me is you had something going on the beginning as a result of
161:32 This becomes a huge basin where sediments and that load of the settlements.
161:40 the whole job going forward, if makes sense? Yeah. No.
161:46 . Once you get that initial amount you you have the potential to to
161:51 a deeper basin. Absolutely, So Bill, let's write this up
161:56 the paper. So I think the to do. I mean I'm happy
162:02 that would be fun. Um um I think I mean the clear the
162:07 things that I would chase after would G Oid anomalies and thermal anomalies and
162:11 if I can find some correlations with bases. And then you need to
162:16 back 200 million years in time. ? Because that's how all these basins
162:20 . Well, except for congo. the present day work. So,
162:23 I it makes me want to look the anomaly over congo right now.
162:27 mean, but anyways, I'll do . I'll do it probably tomorrow or
162:31 . But sounds good. I I mean it's Is that #
162:38 Is that congo? That's fair Yeah, but that's too complicated.
162:45 got the big load of flood, salt sitting on top of it.
162:48 that's Yeah. Yeah, because I , I'm just looking for the only
162:55 that go to present day, the , the Northeast german basin.
163:03 that's europe right, basically. So all that orange area. Yeah,
163:14 area. But those they don't Okay, northeast. So that's Oh
163:30 . You know those, I don't a lot of I don't have a
163:34 of experience working with those basins. mean, I work Poland once I
163:38 . But I don't think I'm I a lot of experience working in that
163:42 of the world. I work but that's too far east of
163:48 Like you were talking to paris I don't know anything about the paris
163:52 . So anyway, whatever. But think that that I don't know,
163:58 just think, like I said, is like your first guess, and
164:04 not your not your last one. because it's just, you know,
164:11 , let's it's interesting. Right? , let's talk about petroleum systems and
164:18 basins. So, we now have idea that we actually have no clue
164:22 they form, but what we they're not hot, there's no
164:26 there's nothing spectacular going on, no . So, if you have to
164:32 a catatonic basin in patrol mode, not gonna make it hot. It
164:38 hot. There's no evidence for any . Right? So, these basins
164:43 probably fairly cold. And that's also you're going to see that the Anadarko
164:48 , it's a cold basin. there's the heat flowing into the basin
164:53 these basins. It's not very it's cold. So, let's keep
164:57 in mind. Let's take a look the sediments and the sediments source and
165:03 potential for petroleum generation. So, the beginning, when we started talking
165:09 atomic basins, I mentioned that these are their entire life. They're around
165:15 level, Right? They can be you know, it can be a
165:19 of the continent that's flooded. It be a shallow ocean basin, there
165:24 a very deep water. And they they're not going through, you
165:28 enormous tectonics or anything like that. , in other words, they are
165:33 shallow water most of their lives. you can imagine um that much of
165:44 is gonna be organic rich, organic sediments that are being deposited here,
165:50 though they're terrestrial much of their You know, if you think about
165:54 , lake sediments, shallow seas, those are organic rich sediments. So
166:01 means that often there's really good source presents. And that is why you've
166:07 of the the buck information. And the Illinois basin and the michigan
166:12 , um prolific source rocks. the subsidence history of these basins,
166:20 just seen tectonic subsidence is almost but if you add the settlement
166:25 okay, it's slow subsidence overtime. also here nothing spectacular. So after
166:32 million years or so, your organic source rocks may actually be in the
166:37 window and some of the deepest layers the sedimentary basins, they may reach
166:42 gas window. Furthermore, what we is that there's never any spectacular tectonics
166:50 on here. So, no complex , nothing like that. Many of
166:55 basins were already there. Then there continent continent collision, for example.
167:00 , they may have experienced some compression some uplift and that compression and uplift
167:07 have resulted in normal structures or anti and as you know, anti clients
167:15 domo structures. Those are these those for very good traps for petroleum
167:23 So, and for example, the basin, DoMA structures that people found
167:27 the subsurface were the first structures that started to drill for oil.
167:32 So these are the first ones you want to go after and we find
167:36 in these chronic patients just because they've around for so long. So that
167:43 these basins um you wanna jump I just want to ask a question
167:49 that these these structures they're basically form you have a space issue, you're
167:54 , you're pouring sediments in and there's place for the goals. We start
167:58 on top of themselves. Yeah. . These are gentle falls,
168:02 This is gentle which is perfect. . Yeah, so some compression of
168:11 Hayden. Yeah, I have a and you know, I don't really
168:15 what, I don't know. So it's completely off base um but could
168:20 have anything to do with the idea having dense material, like a thick
168:27 material deposited um that is eventually um um compaction, you know, is
168:36 a lot smaller because of all you know, fluids in it are
168:42 and then eventually you have this I don't know you see subsidence because
168:48 got smaller. Yeah. So I that that is exactly what we see
168:53 these subsidence curves. My case would yes, it's exactly what's going on
169:00 that's it. So it's basically sediments are being deposited because you have a
169:05 bit of a depression these sediments they become denser they create because they
169:11 , it creates more accommodation space and they become denser, they push down
169:15 bottom a little bit. I think exactly what it is. And then
169:19 only thing you would need, you need to have a starting point,
169:22 ? So a starting point could be mountain range, which is the Appalachians
169:27 are there, they're eroding the sediments transported downhill. River systems form,
169:34 flow in a certain direction. Maybe was a depression there to begin
169:38 You put the settlements there, you loading and it just goes on and
169:41 and on until the mountain ranges gone . So today the Appalachians aren't gone
169:47 there are no large river systems anymore the Appalachians going all the way to
169:52 east to the west coast. you know what I mean? There's
169:55 much going for that. We have Mississippi going down etcetera. So,
169:59 think that's exactly what it is. you have that, you know,
170:03 need to have the initial condition and think that that's that's that's what it
170:07 . Yeah. Okay, thank So we agree. Yes,
170:14 All right. Um So, cold right. There's no evidence for
170:19 So there's no reason you would you give these basins a lot of
170:24 You wouldn't do it. The sediments shallow water probably organic rich um probably
170:31 grains material. I wouldn't expect many in these basins, that maybe a
170:37 , but I wouldn't expect many, would expect Shiels, maybe lime
170:41 fine grain sand stones. Um trips will be present approx will be
170:49 because of all the shoes in their will be present, forming, you
170:53 , formed by nice antique clients. with this whole story, you can
170:58 that this could be pretty good, conventional and unconventional basins. So they're
171:04 explored in many, many places on . Questions about this. No,
171:16 . Great. So we have about minutes left. So what I
171:21 I do Wanna make a start with material that we're going to talk about
171:25 afternoon. Um, so I'm just go out of this power point.
171:41 she open gonna make a start with mother screen here. So what we
171:58 to do next, unfortunately, because need to go through um some basics
172:06 how the cursed and the mental portion the little sphere. Oops, this
172:11 just an all time, an old point that are open just to create
172:17 white board basically for myself. So need to start talking about how the
172:23 three D forms of false versus All the information for example and the
172:28 of the legis fear. And that needed to understand all other basins that
172:33 gonna talk about the rest of today next weekend and the weekend after.
172:37 we're gonna go through a little bit theory before we go back to the
172:42 type of basin. Okay, so gonna call this Realogy Realogy basically tells
172:53 how a rock deforms if you wanted form a rock, how is how
172:56 it going to do that? And call that reality? And I'm gonna
173:02 Realogy of the crust, fundamental reality the little sphere. Based in two
173:08 . The first steps step, I'm to talk about the mental or the
173:12 portion of the little sphere and we're do that before lunch. And then
173:16 other step is gonna be about the , the upper crust and the lower
173:21 . The brittle crust. The Doctor and I'm gonna do that after
173:27 So first we're gonna talk in the minutes about how does the mental
173:32 Now we talked about mental confection a bit and we talked about mental confection
173:37 slow taking a long time. What's , slow is maybe centimeters per
173:50 And that's when it's fast. That's the upper Mental. In the lower
173:54 it can be even slower. It be millimeters per year. So slow
174:00 really slow here. The other thing we talked about is that the mental
174:05 of rocks rocks like we see at surface we call them silicate rocks
174:13 silicate rocks you may have heard of . And then we talked about the
174:19 mentor is fiscus and fiscus is the of the information that the mental
174:27 So the mental is Solid solid We say it can flow or confected
174:40 . But we see at the same this confection is super slow, many
174:43 per year, two cm per So what are we talking about
174:47 But how does solid rock flow It flows by a process that we
174:53 creep and creep of solid rock is following. I'm just gonna go and
175:05 a new fight here creep. So I'm first going to do is sketch
175:14 simple in two dimensions and detail. crystal of a crystal, of a
175:20 that builds up a rock. So you can see it. So in
175:37 case of a silicon mineral, this be silicon and oxygen and some type
175:43 to each other. I'm just gonna it simple. Otherwise, I can't
175:46 it. Just gonna sketch one more below it now. In real
175:52 This is three dimensional. Right? , we would build a three dimensional
176:02 . All right, This is what looks like in our minds in the
176:08 earth. This is not what a lattice looks like in the real
176:14 There are mistakes in this lettuce and of being silica here, maybe there
176:21 an empty space here and I'm gonna the empty space. V and V
176:26 for a vacancy. So in other , the crystal is not perfect and
176:40 not perfection of the crystal is used the creep process to move rocks around
176:47 flow the mantle. So how does work? This vacancy, The non
176:55 crystal, it acts as a weakness that weakness is taken up. Um
177:07 we try to move this mental material . So for example, we're exerting
177:12 or stress on this piece of rock we want to deform the rock,
177:18 want to move material in the How's that gonna work? Work?
177:22 just gonna go to the next slide do that. So we're gonna start
177:26 with the same crystal lettuce that had one weakness in it, A
177:32 an empty spots in this particular So this is how we start
177:38 here's our VR vacancy. These are bones that are um connecting these different
177:47 of the crystal lettuce. And now exerting a force on it. Um
177:54 direction, just gonna sketch it like . But for the story it doesn't
177:59 matter much. Now let's make it in the other direction. Yes,
178:05 we're gonna try to deform this Now, what is gonna happen then
178:12 of these old bulls in this crystal gonna break, the new ones are
178:18 form. So sometime later this may going on, I'm gonna sketch the
178:23 lettuce again, nothing much happens but there was this vacancy here and
178:33 vacancy um is now going to be by the new um lettuce. So
178:40 little bit time later, this one , these balls are starting to break
178:48 this one shows up here, it's be gone connected to those bonds,
178:56 it's gonna jump and then the next step, it may look like
179:21 No, there's actually an awesome So this is it. So we
179:27 from a situation in which we had vacancy in this location, in our
179:33 lettuce to a situation in which we a vacancy here. You see
179:40 So in other words, what's happened this mask moved from here two,
179:48 , you see, this is where is. So we had mass movements
179:54 this direction. So we just we were gonna try, you
179:58 it's sort of force or stress on , we're gonna try to move it
180:01 this direction that happens this little component , moved it jumped, it moved
180:09 location, this is called creep. this is one example of creep.
180:17 , what is important here, you see immediately that what is important is
180:23 because you've all learned in your chemistry that these bones, they break more
180:30 . When temperatures are higher temperatures are , these elements are going to be
180:35 to jump to the next stable place more easily, They vibrate more vigorously
180:41 their around their position. They can out of it more easily and they
180:45 move more easily. So in other , when temperatures are higher in the
180:52 material moves more quickly, which you also see by this process breaking the
181:00 moving on such an element forming new . This is gonna take time.
181:06 you can imagine if this is the that's going on. That flow of
181:11 mental confection of the mental is measured millimeters per year rather than kilometers per
181:17 . You see that if this is needs to happen, this is how
181:21 it it, this is what it . So this is how um fiscus
181:27 , fiscus flow occurs. Now the types of creep. I'm just showing
181:33 this one because I can sketch All the other ones are much more
181:38 to sketch, but that will send at some point in time links.
181:42 you can look it up on So there's a creep that is called
181:46 dislocation creep, for example, dislocation . There's a creep that's called diffusion
181:54 . There's a line creeps, plane . So here I sketched it in
181:59 dimensions, right? We had a . You can imagine if you extend
182:04 into the third dimension, that maybe is not the point, but maybe
182:09 is a line that goes through your . Or you can imagine that maybe
182:14 is not a line, maybe this like some kind of plane of weakness
182:18 is in there. So there's all types of how this creep can
182:23 And you can imagine some creeps they better with this material or some creeps
182:29 better with higher temperature or lower temperature . So there's a lot to it
182:33 we're not going to talk about. this gives you the general idea of
182:40 flow. Yeah. So this is flow. This is what we're talking
182:48 . Some of these creeps are more associated with doctor the information that we
182:53 in the lower crystalline or false Some are more associated with the
182:57 It doesn't matter. It gives you idea of what we're talking about.
183:03 . So we're gonna say that this how the Fiscus Mental mental little sphere
183:09 by creep. And then after the , I'm going to talk about how
183:17 crist reforms questions about this man. . So now it is three
183:32 So I just got one. Go . It's like from what you said
183:38 the grip, it's the process of of the one lattice point towards the
183:44 . Right? Yeah. So within crystal lettuce there are impurities right there
183:49 impurities, a vacancy, an iron has been replaced by a nickel
183:55 Things like that that normally occurs in these minerals. So what we don't
184:00 about is that those are weaknesses. bones are slightly different. An element
184:05 be missing and there's just a void that in that crystal right at that
184:10 . It's those weaknesses that we make of when we have fiscal information or
184:15 information. So what basically happens to bones A an element may make jump
184:22 , find a new space that was before is going to go into there
184:27 gonna sit in there etcetera etcetera. happens everywhere. And you can imagine
184:33 is super slow, right? We're millimeters per year or centimeters per
184:37 But you can imagine if this happens then um in the end you can
184:43 mass transfer and I want to show to you. I'm gonna show it
184:47 you now actually. So I'm gonna out of this power points and I
184:52 a I had a youtube link that it really nicely and I just want
184:59 pull it up and see if I paste it again in uh um in
185:08 chats and then we can look at and that will be the last thing
185:12 do for the break. So I'm paste it in now. Take a
185:20 see if you can make this This one may have a commercial in
185:25 beginning, this is diffusion creep. really cool. You see it?
185:57 when when this process happens like within mineral many locations you literally transfer mass
186:04 one side towards another direction. You that. And if you add that
186:09 , you basically move rock so you flowing rock. So even though the
186:14 is solid, you can start to it and flow it. That's what
186:18 is, fiscal flow. Yeah, cool. Huh? So this is
186:24 people say rocks are solid but they like fluid. Now you can see
186:29 it is. Yes. Alright. else before the break? So then
186:39 afternoon that was really a nice discussion and uh creep mechanisms for uh mental
186:48 polenta. That was really nice. it's the simplest way of showing
186:52 right? Um So let's pick this after the lunch. So after lunch
186:58 gonna talk about brittle deformation, ductile . We actually already have had.
187:03 some of the script types I said are more for fiscal flow, others
187:07 for doctors. So we're not gonna worried about that. We're going to
187:10 something similar for brittle brittle faulting. we're gonna look at the strength of
187:14 little sphere and then we're gonna go form and basins. So what I'm
187:19 to suggest is that we're gonna be here in an hour road that work
187:24 you. Yes. Great. We'll see you in an hour and
187:29 hope you have a good
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