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GEOL7330 Potential Field Methods - Day7 02-10-2023
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00:03 Okay then. So we can the time we we managed to get through
00:10 first half of lecture seven and tonight going to finish that one and I'll
00:17 on the, on the final we should probably be able to get
00:21 through through all of it even though spent whatever 10 minutes messing around with
00:27 with the exam. Alright, so , complex basis. So, so
00:35 we look back at our Wilson cycle , our little uh you know,
00:40 cycle of phases of opening and closing of basins and then my sort of
00:48 of base informing, you know, fundamental elements regarding force and crystal types
00:55 deformation down here at the bottom, have this sort of multiple phase
01:01 And to be sure, I mean you think you can think of a
01:05 margin as having multiple phases of deformation it's rifting but beneath every passive margin
01:12 one half of a rift basin. you can sort of think of it
01:16 way that it's a rift or some just call them drifted margins because they
01:22 lifted margin. But um yeah, don't know, I like to say
01:27 margin because I'm thinking in terms of composition of the cross. Um but
01:34 know that your auntie um van Dijk teaches basin modeling and for john she
01:43 caused a rift and passive virus and of course there's um you know,
01:50 my sort of three groups of of groups of of whatever classification scheme here
02:03 , you know, a continental mobile based on the composition of the
02:08 you know, the substrate and whether continental oceanic or sort of mobile
02:13 people talk about and each one can single anyway, So, so complex
02:20 or basins with complex histories. This what we're talking about. We're talking
02:25 some some sort of complicated complication that's things, uh, you know,
02:35 sort of, well, sometimes I'm what's going on sometimes just making the
02:40 look differently. Right? So, for example, this session here,
02:44 talk about basin and version. Now version is a word that you see
02:49 lot, we talked about inverse, modeling, but that's not what people
02:55 about when they say basin version and word inversion have to be careful about
03:00 . It's a bit hackneyed because, know, she used in so many
03:03 ways and almost doesn't mean anything. say, for example, you have
03:08 sort of pro grading delta system where have, you know, you have
03:15 faults, growth fault as they uh forming, you know, beneath
03:24 beneath the delta or passive barge or . And this system is, you
03:29 , just kind of a slope sort thing. But then if there's some
03:34 of contraction where there's, you conversion forces compression, all forces acting
03:42 this. Then sometimes these things, things will pop up and that's an
03:48 and inversion of the structure. It once down. Now it's up.
03:53 . So these are all being drifted , you know, they're going down
04:00 whoops and then all of a sudden pushed up. So that's an inverse
04:05 basin inversion and a very famous one called the central basin platform. Have
04:12 heard of the central basin platform? ? It sounds familiar. I know
04:20 gone over but it's just, it's a while, I would hope you
04:23 of that. I mean this is Permian, this whole thing, the
04:28 plus the midland plus the central basin . This is called the Permian basin
04:36 it's called the premier basin. If before pennsylvania time. This is this
04:43 when this inversion happened that the structure pushed up in pennsylvania at the very
04:52 closure of Pangea. Okay, when America finished closing, finished crashing into
05:02 America to make Pangea. This is this popped up this, what you
05:09 hear people talk about the ancestral Those are a bunch of Pennsylvanian structures
05:17 are sort of sub parallel to this here and they're all up into new
05:23 all the way up into colorado. ancestral rockies. In other words,
05:28 were, they were structural highs that before present day rockies. That's why
05:36 call it the ancestral, they have to do with how the rockies farm
05:41 they're not related in that way. are much younger. Rockies are formed
05:46 guess severe Lehrman time. But Okay, so this is Pennsylvanian and
05:53 before then this was all one big basin. There's a gravity low,
05:58 mean the basin is thickest right through Delaware and down into the val verde
06:03 then it's thins away from it. mean, yeah, so it's it's
06:10 that classic typical asymmetric geometry words deepest through here and then it gets thinner
06:21 ways, it gets thinner, you , very sharply to the southwest,
06:25 gradually to the to the northeast. that basin was called the turbos A
06:30 to bosa is a, you comes whatever it's a it's not a
06:36 anymore. So that's why they but they call this whole area the Permian
06:39 . All right. Um And here's couple of cross sections through it.
06:45 one right through the very center of here. This is the Delaware
06:49 Delaware basin, the middle and base the central basin platform. Again,
06:54 whole thing is called Permian basin. just in case you, you
06:59 in case you don't get, I , so you don't get confused if
07:01 have people talking about these things. so the Delaware, we just know
07:05 in the Permian basin or the So and so forth. And this
07:10 here is further to the south south and it's shorter. But again,
07:18 you can see the geology is pretty and everything like that. So this
07:23 um a three D. Model that done in the premium basin by my
07:29 Zhang. Um and this is the depth I think. And this is
07:38 anomalies over here. This outline is the Abilene gravity minima. And she's
07:45 it in over here. It's just name given to this gravity anomaly.
07:50 big low sort of trough through But you can see the platform.
07:55 really easy to see. You can the Delaware basin. In fact,
08:00 looks deeper here than here because it now. I don't know see the
08:06 , there's no basin over here. why, why, why do you
08:10 there's this low is So it's like . I mean if there's not a
08:17 here. Um There might be, might be. I think the
08:24 I think that the, Oh this is I think I think this
08:30 the fourth worst basin over here. think this is the paddle dural basin
08:34 here. I don't think that's a , but it could be but why
08:40 I so undecided. You have a a guess at why I'm um sort
08:46 wondering about this low here. I , I don't remember it being a
08:51 . Um I should remember stuff like but I don't but tolerant wise it
08:57 it looks quite like this but I that the Download bases quite deeper than
09:01 one. What's what's causing my uh confusion here. Um hmm. I'm
09:21 at wave legs. I'm thinking about . I'm thinking those. That's what's
09:27 me. Our wavelength. So remember wavelengths for gravity can be related to
09:41 uh some gravity. That's the It's the mojo crystal thickness. Why
09:58 I always get that wrong? Alright. So um Right. So
10:05 , so I'm confused here because even I think I know that the Palo
10:10 is up here, the Delaware is , the midland basin is here.
10:14 thinking that I'm thinking that this could this could be, you know,
10:21 on the base of the crust. crust could just be thicker here.
10:25 even though there's not a base in crust can be thicker for some other
10:30 . So yeah. Alright. Okay. So she made a model
10:36 . I think we're looking at this right here. A two D.
10:40 is controlled by some refraction stations, like our model from our exercise.
10:48 so the interesting thing about this is she's modeling the premium basin, the
10:56 basin platform as a structural high, is correct. Um She's really constrained
11:05 well controlled for this shape. So just putting in some lower densities up
11:11 . I see the way. I think that's the right way to do
11:15 . But I mean I mean I on her committee. I was not
11:17 advisor. I did. I did her. I don't think no explain
11:24 discomfort with this. But here's what thinking. So she's almost got the
11:28 here if these are basement terrain then need to drop all the way down
11:34 the to the through the top through upper crust. Maybe not so much
11:40 lower crust because that's that's a little you know that's lower crust is typically
11:47 and stuff. But And so she this 2.64-2.75 for the basement rocks.
11:56 me that's just too big of a . And if you made these things
12:00 all the way down, I mean whole made a hole like a basement
12:06 then you have to make that density . And so the contrast between the
12:13 this pink basement and this yellow basement be far less. That's what I
12:20 I think that and that would be reasonable to me. Right. I
12:24 large density contrast with that sort of . Just just don't make sense to
12:29 . Why would why would that be mean if that were the case,
12:33 would why would the top of I guess you could argue it's been
12:38 away. I don't know. But that's that's what sort of budget about
12:42 model? Well but I still start thesis. So yeah. Um And
12:51 she made so here's on the lack the mojo depth. So it is
13:04 she hasn't getting deeper beneath this I tend to think that this is
13:11 a compositional change. So and then did the density inversion on the on
13:19 upper crust. And see it ranges 2.74 to 2.77. So it's just
13:27 . Right? I mean it's not of a contrast at all through
13:31 So even though you have all these and lows, they're very subtle,
13:36 And I agree with that. And she made some basement trade interpretation.
13:44 she did that based on her modeling . So that was kind of kind
13:48 Okay, alright. Um I think talked about this. I think this
13:57 be the third time we've seen this . I think we saw it
14:01 Already saw it for four arts. I think I showed it to
14:05 We looked at it once before But remember this is the caribbean plate
14:09 how the fair line plate tore As you know, the subduction flipped
14:17 the caribbean plate tore away. So caribbean plate, the southern rim,
14:22 we call the southern rim of the plate right here. Is that a
14:27 history. And there are basins formed along here. Um uh They're not
14:35 indicated, but there's bases that formed uh in Colombia and Venezuela, all
14:43 the northern uh coastline of south America what I'm going to call the southern
14:51 rim, but there's also part of place as being subduction, even though
14:57 northern part, there's no subduction. all just, there's just a
15:01 it's like slip boundary up there. that's kind of an interesting thing.
15:05 did this part? Why is There's such convergence down here, but
15:12 a little bit up here. In case, we're going to take whatever
15:16 steps across and look at all these that are forming along here. And
15:21 complex because this is a right, is a passive margin. And then
15:29 plate, the caribbean plate is moving it, uh you know, trans
15:34 the transverse direction. It's not like not, there's the tectonics is
15:39 you know, normal to the passive , which is kind of like,
15:43 know what you what you normally It's this is being, you
15:47 the place just driving right past like scraping bits off. And that's
15:52 crazy things are happening. So that's idea. So we're going to start
15:56 uh Columbia over here and then we're go, we're gonna look at the
16:03 , at the base is right the falcone basin. And then there's
16:08 basin here and it's called, well a rift in here and then there's
16:15 more basics. We're gonna look I'm sorry, two more bases on
16:18 . We're gonna look at in through . Um but this isn't really
16:24 This is a uh really, I like these figures because they're showing,
16:31 , so they say there's six tectonic separated by these dash lines. I
16:36 know, I really agree with but it's okay you can do that
16:40 of thing. Um Yellow arrows, they have relative gps motion relative to
16:46 fixed south America. In other these blocks are moving relative to fixed
16:53 America down here. And as well up here, these arrows are
16:59 you know, they're all scaled to same but they're showing the relative motion
17:04 these blocks. So yeah, there in motion right now. I mean
17:09 a lot of convergence plan, There's here, you know, sub ducting
17:14 the southern part of the Caribbean plate here and then also going back here
17:20 G. A. C. Is great arc of the Caribbean. Uh
17:25 and as as it was plowing through , right beginning right here, there
17:32 bits of it that were kind of and kind of left behind abandoned as
17:38 arc moved to the east relative to America. So that's great art from
17:45 America. You see that a And so that's what all these islands
17:50 . These are parts of the great . And in fact they they dashed
17:57 yeah. And it goes right up the abs Ridge which remember is a
18:02 island arc. Remember that of course lesser Antilles is an active island arc
18:08 . There's volcanism happening right now. they call the southern caribbean deformed belt
18:18 through here and it consists of the Antilles. So these are these bits
18:23 the great arc that were abandoned. let's see this is the Wahida Wahida
18:34 which is right there and then the peninsula which is right here. Um
18:43 marta. Uh let's see who Bucaramanga . So that's that's going right through
18:53 and then the iPCC. This is L. P. Large fault zone
18:57 is thought to be a transformed body money. And below it's free air
19:03 . And we know it's free air because it looks like both um a
19:07 , right? It looks like The island arc is a big
19:11 Big honkin gravity high that's ready island . The Aves ridge is a
19:19 the basin is a big low, all these islands producing gravity high.
19:25 we know it's free air gravity because looks like now they divided it into
19:33 types and they did some age This is the part that I find
19:37 crazy they have. So this is age of the dating which is
19:46 Remember that the caribbean? When did arrive? It arrived? You know
19:52 ? You see it arrived between 90 75 M. A. right 75
19:58 . A. It still wasn't in , But they have rocks here dated
20:03 . Is that right, 74. they have cretaceous cretaceous, that's older
20:09 60. So in my notes let me see, I got my
20:14 . They say they have great argument . Great arc of the Caribbean magnetism
20:21 between 128 occurred from 1 28 AM 2 70. For yes. So
20:30 74 is a. Is a date 28. Wait a 2nd. 1
20:38 . I mean that's way to hang here. So what does that
20:43 That means you see when did this , when did the polarities change?
20:49 after 90. I mean after 90 . A. So that means there's
20:54 28 rocks if they found something. do they do they have any data
20:59 ? 1 10 1 28 right there are rocks these these are are the
21:08 as Tobago remember was Tobago Tobago. off it's dead. Tobago's off the
21:18 up here. That means they these is 110-128 I would say 1-14-1-15 I
21:28 say. Those are bits of arc the previous arc. The one where
21:34 polarity was um where the slab was to the east instead of to the
21:42 as it is today. So that's really interesting. I mean that's that's
21:48 quite interesting. I've never talked to about that but I should probably
21:52 That's paul man. He was this vince. I don't know I don't
21:56 never met vince but I mean palma a professor on campus. So I
22:02 have talked to paul about that. that's something that's that's really interesting.
22:07 Yeah and then below is a two time basement structure map showing the debt
22:14 two way travel time. So that's yeah that's really interesting. Okay.
22:23 . And then I'm gonna show you seismic lines just so you can see
22:26 the structure is a lot on the caribbean room. Let me show you
22:31 C. D. And E. . B. Is right? There
22:34 a C. D. And And here you go. So you
22:43 I mean here's the thrust front and , you know, seductive. So
22:48 you know this is like non rigid , right? So that's the it
22:53 like a subduction zone. It looks there's convergence. But the convergence is
22:57 , right? Remember this part? caribbean plate is like moving towards you
23:02 of the plane of this, of cross section. So the structuring is
23:07 complicated. I've done a bunch of along this large and for different
23:11 Yeah. I mean it's if you you're thinking about forces then they're orthogonal
23:19 this picture or I would say more oblique. Okay. Um now let's
23:31 at Columbia. Um So here are bunch of terrain that were created onto
23:38 northwest part of Colombia. Um As Caribbean plate was shoved in here,
23:44 ? Or as it formed while while know, while the arc, great
23:50 crashed into here and see they've identified say realms. I would just say
23:58 but I guess I don't know I anyways um Yeah Guiana shield uh cabo
24:13 . And then this is so this this is just a nice picture.
24:19 I don't know how to pronounce it but then then Sanchez Rojas and Palma
24:28 Rojas and Palma made a three Gravity model based on a bunch of
24:33 . They had refraction data, they seismicity from you know earthquake um They
24:39 reflection data, they had all kinds data in here and they made a
24:43 D. Model because there's subduction going here from a couple of different
24:48 There's subduction from the Nazca plate out in the uh pacific ocean that's sub
24:58 beneath you know south America and central . You know that subduction zone plunging
25:05 know, dipping to the east. then there's this southern part of the
25:11 plate which is also sub ducting beneath corner of south America of Colombia.
25:18 it is way, way complicated tectonic . It is not a nice static
25:24 but there's a bunch of features They're all labeled but I'm going to
25:29 you three cross sections A. And C. And here's kind of
25:33 A three G. And are you in here with these beach balls with
25:39 uh play solution. Beach balls I learned about them before. Yes and
25:45 and intro video. Okay so this like a three D. Volume with
25:51 things plotted in three D. So is kind of manager friendly I
25:57 And yeah here's the seismicity depth I that's in these. Is that I
26:06 . Yeah because there's some red ones maybe some blue ones down here
26:10 Okay so that's a nice little And here are the three cross sections
26:16 . B and C. Um um has a lot of control. He
26:23 done depth estimates. He has seismicity ? He has the magnitude of seismicity
26:29 in the size of these circles And oil or depth estimated estimation with two
26:39 um zeros and ones. So that's a lot of these symbols are all
26:44 here. Um He's done mojo depth from spectral analysis. So how do
26:58 do that? He's probably done that spectral analysis, gravity data. So
27:03 then he's calculated nice a static This just this place is this
27:07 This region is not an isIS static . So I don't know what
27:12 I have no idea what that But if he's using that to constrain
27:16 his model, I think that's incorrect basically what he's done is the they
27:25 their control and that's all these symbols they mean a lot of different things
27:30 basically you can look at it kind so you know that these these are
27:35 you um sort of like a minimum of the top of their saying upper
27:45 and lower crust right in here. then they have the atmospheric mantle down
27:52 beneath the white line. The white is the white line is the base
27:55 the crystalline crust. And then for for continent and then just this two
28:03 dark green is oceanic crust. Light is oceanic atmosphere, right?
28:08 With a severe mental issues here in density contrast is 3.343 point 353.341.
28:20 . So if you notice there's not of a density contrast for the deep
28:25 , 3.4 versus three point Well, 4141 She got here three 35.
28:39 is something I've seen people trying to subduction zones. It's really hard because
28:46 I said, they're not static Which is sort of how these models
28:52 , right? But do not mistake . Plus, they don't really produce
29:01 anomalies. I mean, you um is this gravity low produced by
29:07 slab? Probably a little bit, know, but if you look at
29:11 density contrast, there's not much of density contrast, you know, they
29:16 a big one here. So this the crazy part here is this this
29:19 the caribbean slab, this green one this purple one that's the Nazca slab
29:25 in from the pacific side which is know, you're looking at sort of
29:30 sort of bent or flexed. So really crazy. Um, I'm kind
29:40 ambivalent about these three models. I , as, as a rule,
29:45 don't like to see so many segment , especially with density. I mean
29:52 Magnetics, you almost have to, with gravity, it's just really sort
29:57 painful for me to look at that . I just think that there has
30:01 be a better way. But maybe tried other ways. I don't
30:05 Um, in any case, you , I'm not even talking about the
30:11 fits the fits pretty good. I , it's probably the fit is probably
30:15 than, than the model, I mean the models shaky is on
30:20 set. Okay. And then of they made, they rolled all this
30:25 into a 3D model, which is ambitious and I mean, you
30:29 hats off to these guys for tackling problem, but it is pretty
30:34 I think that it certainly would be you could use if you want to
30:38 into this part of the world a bit more. Here's the base of
30:42 crust. So these are contours in kilometers subsea. So there's the,
30:48 , I mean in kilometers subsea, the 45 35, 25, 2015
30:59 , 15 km. Now the water out here is, I guess three
31:04 probably I don't think it gets much than that, maybe 3.5. So
31:10 it's, if it's 25, 15 , That means the crust is 10
31:19 more Kalala stick. So that's why call it. They think it's all
31:25 plated or large parts of it are plated, especially up here in the
31:31 ridge, underplayed by the, you , magnets from the Galapagos plume as
31:40 is that part of the, at time Farrell and plate passed over and
31:47 the right here. Our friendly little transect but also they've contoured the dipping
31:56 from north to south right, The slab is dipping south this way.
32:01 it's kind of just like the corner the places or the place, you
32:06 , so it's just the corner of America and then here's the dash lines
32:12 the nascar play, which is part the pacific pacific. So it's really
32:18 a sharp bend in it there. don't know that seems that seems pretty
32:26 to me, but yeah, so if we step over to
32:34 to the east a bit, we to the beneath this um, what
32:39 the name of that peninsula? the paraguana paraguana peninsula, there's this
32:52 column basin and it has some intrusions through the middle of their uh,
33:01 , what did they say? They ? The uh, Igneous intrusive buys
33:09 crop along the axis of the okay, along the axis of the
33:13 . So through this way, I'm . Okay. And um, they
33:22 a model. They did this model here. So this, this map
33:25 is uh, gravity anomalies. let's see here. That's a
33:34 So this is, this is free data and I'm not and I know
33:39 because again, it looks like This is the water, it's
33:44 It's a gravity low so high here the islands are to grab you
33:48 So this is all three year data least the obstacle part is free
33:52 It looks like it's bouquet on In any case they have a cross
33:56 that goes through right through here. this is where the falcon basin
34:01 right, right, right in there going from, let's see this in
34:14 case north is on the left something on the right side. I
34:19 make bottles that way. But in case, so the falcone basin is
34:25 here and see they made us this . So, so I'm not doing
34:31 disregard. I mean, I think very believable with these geometries. They're
34:35 they are using some multiple densities, just very few. So I just
34:40 their reasons for doing that. It interesting that they have to change the
34:44 of here, right above the So maybe there's some problem with how
34:49 densities for use it for that. any case. I still think it's
34:55 pretty good model and why is the what's going on with that? I
34:59 , you can see it's high It's interesting that it fends right near
35:05 end of where the slab it so it's a trans tension all feature.
35:10 , Because along this margin, You see the same thing like along
35:16 san Andreas were depending on how the bends, how that and in this
35:21 , how the subduction zone bends, could have transgression or trans intentional
35:28 So you can have a case where producing a little basin and right next
35:36 it, a long strike along the caribbean rim. You can be producing
35:41 little, you know, convert structures convergence or whatever uplifted area. But
35:56 you catch my gist with these is that what I'm doing is I'm
36:02 looking at this and I'm taking what we've already learned about rift
36:07 passive margins and, you know, basins for our base and just taking
36:14 we learned from those. And I see elements of all of those in
36:19 complex zone here. So, throughout , there are uplifts and there are
36:25 trans attentional basins and structural highs that a result from this oblique convergence of
36:32 caribbean plate. But you can just that down into the smaller bits and
36:37 you can understand it in that So this is the uh gua deco
36:45 , would you say that that What would you say? How would
36:49 say that? Um Ok, Ok, ok. Yeah. So
37:03 is this is actually a little four . Right? But it's remember the
37:08 that produced. It is oblique. um disorientation for these lines seems to
37:19 should be actually be this way. they did them anyway, they did
37:24 this way. So this is the sorry, terry Randall. What's
37:30 So they're calling these geodynamic transect And have reflection data along parts of
37:38 I think they have refraction data as . Um what we're looking at here
37:44 residual blue gay from a 10 climber continuation. Just because I want to
37:49 if you can see any structures in , um residual glue for land.
37:57 still freer. Right, It's still out here. Yeah, I think
38:02 , yes. And then yeah. this is the thrust front through here
38:10 you got the san sebastian, the slip fault and the el pilar.
38:14 all of this has to do with , you know, the caribbean slate
38:19 moving east relative to south America. then this range is formed from the
38:28 and it's produced a little foreland basin . This is the magnetic data.
38:36 magnetic data, we're looking at that all of a sudden you have these
38:39 wavelength here. So the basis getting . You kind of get a better
38:43 for how this basin is formed if can trust this mag data. Um
38:49 then it's kind of smooth out here you can see that things are shallower
38:54 then deeper of course. Um There's low over the mountain range here or
39:00 little this little part of the northern . So I would just interpret that
39:09 a compositional thing because I mean, don't know, I don't have to
39:14 if you do it. And in case. Yeah. Um I think
39:18 gonna. So these are line interpretations reflection data, right? So A
39:27 a prime is right here and Two B. Prime. So this
39:30 going right into the well this is this is a four land for this
39:36 . But then there's a rift The Espino rip Espino grab in which
39:42 through here. Now. Is this trans intentional feature? I mean you
39:49 convergence. This is why I'm calling complex examples because or complex basin because
39:56 here you definitely have kind of an right? For B. And in
40:02 part of a you have this your classic foreland asymmetric geometry. But
40:09 right over here you you run into grabbing that's so maybe this is maybe
40:15 four land again. And I guess how it works. The four land
40:19 just this southern this this northwestern sort bit from here. Let's look at
40:25 gravity again. So the four land here and then the sp no drift
40:33 no grabbing is right there minute next the monitoring base. So.
40:42 Um Yeah, I don't know, mean you have to play around.
40:45 see what they did with their So this is going to make the
40:52 that these are not the whole these just decided that and they make a
40:58 of these longer profiles. Okay. that the models I'm going to show
41:02 are these long profiles and they include work from this from, you
41:09 interpreted from these smaller sections. This my understanding from the paper. So
41:15 , so here's the little the seismic right in here and right in
41:21 Mhm. Um Yeah. Okay. look at the range. This is
41:34 or minus 75 mil ago. So 100 and 50 mila. Go.
41:39 is. So these anomalies are really anomalies. And what they've done is
41:45 said there's this little thrust, this cordillera thrust belt, you know,
41:51 sort of obliquely been, you kind of causing, you know,
41:56 this deformation here and then you You have this other basis. So
42:02 Espino grabbing, It's all the way . And it seems to be unrelated
42:08 this thrusting here. It's amazing I mean, this is, you
42:11 , you have a grab. The explanation for that grabbing is that it's
42:16 it's a fossil grabbing right that that formed with with the break up of
42:23 and the only you can't really figure out with just what we have
42:27 But that's a possibility. Okay. we can step uh east a little
42:35 further to the east. Here's our Espino Gavin, here's the Mcferrin
42:42 It's a big giant and now this a foreland basin and it actually turns
42:47 a passive margin. It's a four in this direction from Northwest of South
42:55 , with the 8th symmetric part being here because of the convergence. But
43:02 here this is a passive margin dipping the south into the, you
43:07 whatever the equatorial atlantic ocean, the ocean. So way way complicated.
43:14 we have to just sort of use tools or use what we know about
43:17 basins and try to investigate that. you can see gravity low right
43:27 What's interesting to me is that Espino . I mean, it doesn't have
43:31 of a much of uh you uh it doesn't have much of a
43:38 signature today. And in fact look what they do, they don't really
43:43 call this thing a gravity but it seem to be they didn't even model
43:48 much relief on it at all. fact. Yeah, I mean it's
43:53 an afterthought, I mean, it's interesting. So this isn't really
44:01 mean, I I really liked how overlaying this map. I was really
44:05 with, you know, I like map quite a bit there.
44:10 Comey their math because they're showing all regional structures. Of course the the
44:17 time for the subduction zone, but got the ball to matt in
44:21 in the prism and then the Tobago here. Barbados, there's Tobago and
44:28 Basin, then all these these these of the great arc that were abandoned
44:35 the plate kind of scrape them And then it's showing the christian prison
44:41 top of the caribbean plate as So, and then this little thrust
44:45 over here. So I think this a really well done matt. That's
44:49 gravity. This is the bouquet, is okay, so this is boogie
44:55 freer offshore. But now its bouquet . You want me to ask you
45:04 I know that. You know the . Um because it's a low over
45:15 ocean. No, where is Where's the ocean at? This is
45:22 ocean over here. This is it's the blue over the Venezuela.
45:29 , I don't know the land goes the way up to here.
45:35 oh ship. Okay, I'm really on the spot. I'm sorry,
45:45 promise. I'm smart. So it's it's boo gay because it's a high
45:54 the ocean crust. The crust is . The mojo is coming up.
45:58 mojo density is 3.3 crust. Dancing 2.9. So there's a big
46:03 it's the second biggest density contracts, is the biggest content to contrast.
46:10 when you move that, remove that , then the second biggest density contrast
46:15 the base of the crust. So mean many times many ways.
46:23 so that's bouquet, here's the residual it. And uh you can see
46:32 trace of subduction zone in the christian doesn't really make much an anomaly.
46:37 yeah, you can see um before am based in here, you can
46:43 the shape of the asymmetric shape where getting really deeper, right into the
46:48 into the foothills. Here's the magnetic . This state is very average.
46:56 think it's kind of sparsely stations are of sparse. So it's not really
47:03 what's going on here. But you , but if you just Okay,
47:11 just gonna if you just ignore areas you know, basically there's no
47:16 But you can definitely there is some up here. So again, what
47:20 we know from magnetic data? It's about wavelengths, short wavelengths, things
47:24 shallow basement, shallow long wavelengths basement deep. So the matter Marine
47:32 I mean there's some shallow stuff going here. And the Robin the
47:38 oh grab in and uh Gwahd Ico here. You know, there's not
47:46 days that the date is pretty, mean it's pretty smooth. So it's
47:51 with being deep or it's just not . So but this is interesting.
47:58 you let me just go back and . So the deepest part of the
48:03 four land, the monitoring basin and just ramps right up onto the Guiana
48:08 which great parts of our outcropping. so it's getting and you can see
48:16 how the how it's smooth here. then it's getting shorter and shorter wavelengths
48:21 though it's negative. Which doesn't mean deep because it's magnetic data. What
48:28 this blue and red mean? Does mean it's deep or what does it
48:36 ? Is it I'm sorry. Can repeat the question? So this is
48:41 data and we know this is getting because of the wavelengths are getting
48:47 Yet it's colored blue and this is . Why what's going on there?
48:52 isn't that for me is it steepness shallow? Well I. Yeah
48:58 I was saying that we know it's deeper here and getting shallower because of
49:02 wavelengths but but the intensity of the one. This is red, this
49:08 blue this broad blue and this What what does that mean? You
49:15 ? Wouldn't that just be like a drop like a because if it's it's
49:27 shallow. That just means it's a park surrounded by why is it if
49:33 shallower why is it blue instead of ? Why why is the magnetic
49:41 Blue. Why is it a minimum minimum? It has superimposed on these
49:46 wavelength anomalies which tells you that things shallow perverse. Yes. Yes.
49:54 you. Good job I'm there but not I don't know how to say
49:58 . Okay, the field is That's the only explanation I can think
50:05 because I know it's getting shallow. shield is the outcropping shield is right
50:11 and this actually shows you terrain within outcropping shield, right? Because you
50:16 see that this is changing. So are not, you know, are
50:22 the same everywhere, so Okay um , so we're gonna, this is
50:29 are cross sections, you can see down here below and these cross sections
50:33 going from, these are kind of . It should be northwest on the
50:37 side for me, but they're doing southeast to northwest. So they're going
50:44 from close to the shield Into the land base. And so this is
50:50 to show you the japanese, these on two way time, but you
50:55 see that you're coming up onto the , right? The base is
51:01 you know, it's the deepest part you know, classic asymmetry. So
51:07 are going, those are going from southeast on the left to northwest on
51:13 right, so they're coming right right off the shield into this four
51:20 , which is, you know the geometry, you know, I look
51:25 this for a while. What is thing, what's going on then?
51:27 realized that they're not, you most people would plot this northwest of
51:33 , you know, because because they're , you know, in that way
51:38 , I don't know. Um so um we're gonna end our little
51:48 along the southern caribbean rim kind of into an area inside this motorin uh
51:58 and its river basin? S premier Espino grabbing. There's another line
52:05 A model to model was that was along these seismic refraction stations. And
52:11 had some wide angle reflection data as . So in here there's there's the
52:18 of squares, uh um White stars shot point squares are recording points.
52:24 receivers and shots and okay, there's kinds of three kinds of recording
52:34 And then here's that on top of bouquet anomalies. So again, here's
52:40 right, here's the outcropping Guiana Here's our little four land turns into
52:45 passive margin as you go to the of to the coast. And then
52:51 Espino grabbing is right over here. the magnetic data. Remember here's our
53:00 polarity. You can see the depth the base and you can see the
53:04 getting deeper as you go to the . And then all of a sudden
53:07 gets shallower. Again, all these wavelengths here. And this is their
53:15 . So this is their model they with basically with the seismic velocities.
53:20 then these are all velocities posted So this, remember we looked at
53:28 last 5.55.9. So this is this probably the, I wouldn't make it
53:34 deep. I would make it I think 5.9 is a little high
53:40 um I guess it's okay. I that's okay. You can make that
53:43 top of the basement And then 6.0 6.7 into lower crust. 8.1.
53:51 definitely mantle. So yeah. here's a question. How would you
53:57 these velocities to density? What would do? Um converts into dense
54:10 Oh, there's a formula. Um right, that's right. There's
54:22 the velocity velocity to density conversion. , so and then here is oh
54:30 the gravity model. So here's the model and here's the gravity model for
54:38 . So they're calling this the oriental . But this is the most
54:42 this is the most serene. And don't know if this shape is if
54:45 like the shape that much. But , upper crust lower crust.
54:53 quick question for the for the I mean, I know there's a
54:59 but it's not like the because I it's like mass divided by volume.
55:04 how do you know that? You do the mass. So what was
55:07 name of the formula that we use ? Are you can quantify, I
55:14 you a table. I showed you table. Um And there's a settlement
55:22 like Gardner. Um I think I it right in here. Hold
55:28 I'll show it to you. Um actually think I did that with dr
55:39 like the both module assess and okay. I was just like,
55:44 know it's not like I see Oh no, here it is.
56:09 right, there's a paper by bro that summarizes a bunch of these
56:14 Um Jerry Gardner used to teach at University of Houston, Really smart
56:20 Um he did a bunch of laboratory and that's probably what you learned.
56:24 gardener equation. Um can you see screen? Can you see the table
56:38 ? Okay, so there's the knife which is from Ludwig and others in
56:46 of the volumes of the C Right? People still use it like
56:54 and that's this black line here, black diamonds. So the velocity in
57:02 per second along the bottom axis and and gravity per cubic centimeter in this
57:08 one. And then christian ceremony have some of this work and they for
57:14 . That's plotted on this here. Godfrey and others have done some here
57:22 culture actually summarized all this work. um jerry Gardner did did laboratory measurements
57:31 individual rock compositions, types, sandstone shells, limestone, salt,
57:40 and hydrate. That's all these other little ones. Right? So if
57:45 have your velocities, you just go this thing, you can just look
57:49 up but there is a formula Here it is. So this is
57:55 is in meters per second. So one, these are the terms
58:01 The the whatever the uh right, this is, you know, this
58:13 . Right? Uh It would be a 0.32 plus one point oh five
58:19 10 to the minus three X. mean x data accident, Y of
58:25 . Why is it density? And this is like X one, X
58:29 x cubed X. You know like . So you can actually fit
58:35 oh wow, you can actually fit to these. So someone did this
58:42 me and then they see they even the whole derivation down here. What
58:52 this mean? Does that mean the too big for the for the
58:56 I'm not I'm not an Excel They did it in feet per second
59:02 well. Solid. Yeah, because a there's a there's a number there
59:12 , whatever. So yeah, so how you would do it. So
59:17 would look at those um you look at these velocities, you could
59:24 do that. I mean this is , you know, this is not
59:28 a two D model, this is a continuous function. So you can
59:33 do that continuously for here. All different velocities. So that's what they
59:39 2.89 C2.8 something around there. So was that? 2.8 something or
59:44 Yeah. Anyways, I should get table back up. Okay, so
59:52 see what they did. So they 8.1 is 3.3 and So 8.1 is
60:04 over here so see that's right about right right there it is. I'm
60:10 looking at Nate Drake 2.8522 point They 2.52.92 for lower across 2.85 2.92.
60:21 that's 6.5 kilometers 6/6 kilometers. And was yeah I don't know 7.1
60:37 That gives me at 6.5. Yeah don't know. Anyways that's how that's
60:45 you could do it. But this pretty typical. I mean you know
60:50 have they have I guess this outcropping up here so you have to catch
60:55 anomaly by changing the geometry of the of the crust. Now. That's
61:01 not a bad thing because I mean you only have one thing to do
61:06 all you can do. So that of gives you some you know kind
61:11 pins down this part of the model a way. Right? I mean
61:16 if you change anything in here you change everything. So that's okay.
61:25 crust That's tank oceanic crust is like km sick. Um Yeah I don't
61:34 so. Oh yeah I think I I think everything in here is I
61:49 this whole thing I think everything in is dinner. So this is going
62:00 to 40 con like I don't The only way do they have,
62:07 a second. They have refraction data you, don't they? That must
62:15 what these are 35. I'll bet that's what these lines are here.
62:20 are from their stations because they have these refraction stations here. That's
62:27 That's really sick. So what does mean? What does that mean?
62:35 how far just go? Let's look that. So why Star Shop
62:45 So does the model go all the ? Doesn't even go to the
62:51 does it? Oh wait, the is right here. The coast is
62:59 here. So the market goes way beyond the coast. Oh,
63:04 dash line. But it doesn't really . Okay. I don't I don't
63:09 how far it goes offshore, but goes up quite a bit. I
63:14 know. I think, I think way too thick. I mean,
63:19 don't know if this part is thinking , you know, the hot
63:23 but I don't think so. I think there's a I think there's
63:29 issue here. Yeah. Alright, just move forward. Ok, so
63:38 flood the salts. Remember? Large provinces. They can exist also on
63:45 here. The Siberian traps. Here's Columbia River basalt. These are on
63:50 . The deccan traps are actually um part of India India is very faded
64:00 , but that's all on top of . So they can also exist on
64:05 And then remember that I have the , the paranoia over here and the
64:10 flood basalt are really, uh, steel. The volcanism covers an area
64:18 1.2000 km2. Um, they estimate km3 of basalt. So yeah.
64:30 it's those assaults sit atop overlying a called the paradigm basin. So that's
64:40 , I mean, they're, they're big. So they're huge,
64:46 The decade traps flood the salt. from the reunion hotspot, that
64:52 It erupted a big outpouring, but one actually lived longer and produced hotspot
64:59 all the way down into the indian . Here's a picture of it right
65:05 and the thickness of them Up to km. Now, wait, most
65:12 this is in the range of I think. I don't know why
65:17 might be some, I don't but this is what they look
65:21 Just alternating layers just flooded. You've of, you've seen the Colombian,
65:27 assaults, Have you seen Colombia? , structuring whatever columnar basalt?
65:36 yeah. And then here are the traps. Now they're not very thick
65:40 all. But look at look at is from the ocean, how they're
65:47 to erosion there. Good, except traps. Okay. They erupted in
65:55 , their pennies look in the um, Their thickness, their main
66:01 seven, only 700 m. So not as thick, but they're all
66:08 here on this side of the western Canada basin huge. And then we
66:16 our own here in the United we have the Columbia of river basin
66:21 a Columbia plateau right here in Washington Oregon. And then here's the extent
66:28 the flood assaults. The Columbia, river basalt, I guess is what
66:34 call them. And uh they they're c they're Mycenaean age. So there's
66:46 bunch of wells in here and there some exploration, they actually drill,
66:52 drilled through the Columbia flood assaults, are about 11,000 ft and they produce
67:00 from them out here in the Washington the, you know, eastern
67:06 Um And then here's the cascades come here, right, and then right
67:13 and then the coastal ranges are out , right, right through here.
67:19 So this was, I've been up three times the first time I did
67:23 little project for a company, they to, you know, a little
67:27 company in southern Southern Canada in british and they wanted to explore for some
67:34 . And because this is right, know, it's right near there,
67:36 markets, there's lots of population and guy was working for, he was
67:43 local geologist in Tacoma and he asked if I'd ever been out there and
67:48 said no, he said, well got to come out to there,
67:50 got to see that, you got see the basin, which was very
67:54 . He was a total geologist and spent like a few days, you
67:58 , exploring the geology out there. course this is wine country.
68:03 you know, we had a pretty old time. Um The winds out
68:10 just F. Y. I. is this is a really important
68:16 The winds out here, the best are west of the river, see
68:21 Columbia river comes down here and it out that it's the border of Washington
68:25 Oregon. It's east of the And there's a little college town of
68:31 , Little Liberal Arts College in a called Wallawalla right here in us
68:38 You stick east of the river, of Walla Walla and north of the
68:44 north of the state line. There's 300 wineries in there and the wines
68:51 this part of the Columbia River Basin ridiculous. They're as good as anything
68:56 California, I swear. Um It to do with some flood flooded soils
69:03 came down here, but it also to do with the assaults. You
69:08 , I mean, the meteorology of assaults, It's really good for
69:11 so yeah. Um Yeah, so , that was sort of like an
69:17 I guess. Um Okay. Uh you want to take a, I've
69:24 talking about our 20 you want me , I only have, I probably
69:28 have maybe, I don't know Less 10 slides to go to finish this
69:35 . You want to finish this and take a break. Yeah, that's
69:39 . We can finish this. alright, so okay, so back
69:44 the serious business now. This this a busy figure, but here's a
69:48 map of the Columbia River of There's the, the Yakima fold belts
69:53 are big long basalt and declines, there's a there's a plot here,
70:01 a gram here and the left side kind of wraps around things and what
70:07 showing is it showing that there are are six units. I think there
70:10 more. I think there's 12345. seven different units, but these are
70:16 six of the units that have the outpouring of the salt by volume.
70:24 whole basin is filled up with the , right? And by volume,
70:29 is the different units. So the one, the biggest one by
70:33 85% of the assault in here are grand run assaults. And over here
70:40 the timing, here's our little chart millionaires 17 million. This is all
70:46 . The Grand Run erupted at about I guess 15 0.75 M.
70:54 Right here. The very first ones here, about 17 M.
70:59 But it wasn't very much. In this Uh that's this one right
71:06 so it's just about 5%. And um this one's not here. Snake
71:13 . Snake River is not there. , Snake River, that's down
71:18 that's why. Okay, this is just from the Columbia River. There's
71:22 couple different this is back seat for material here. And this is this
71:27 plots from Tolan. So I'm kind crossing things up. But anyways it's
71:33 to look at this because this is very favorite geomagnetic polarity reversal scale which
71:40 identified five A. Five B. and so forth. Five C.
71:44 here. Okay, five B. . R. Means reverse. See
71:50 solid colors are positive correlation. And at the Grand Run. The Grand
71:55 is negative polarity and we know that from rock samples. Okay, so
72:05 it erupted during 5b.1 are the normal for these crowds. It gets pretty
72:12 because every time we get more data keep subdividing these things. But
72:18 that shows you the the deposition of difference. Assault units in the Columbia
72:25 . Um Remember the wells. So some cross sections drawn through the
72:31 This one starts in the northwest To a prime and it connects up
72:36 these different wells. And the basalt . Is this sort of plus symbol
72:41 . This center here. So there paleo jing sediments. But ain't that
72:46 there's I think paley uh there's a I know maybe a legacy. I
72:53 there's a scene and a legacy. if I remember correctly and then you
72:58 the and then you have you have know, sediments piling on top of
73:03 . So that's what's happening now. is the ice a pack of the
73:08 run in terms of meters. So 800 m to over 33 a half
73:15 thick this unit. So it's really . It's a bunch of it's a
73:20 pile of assault without a doubt. , now going from southwest to northeast
73:29 through, you know, we're crossing of the one of the same wells
73:32 think to be in 19. That's show. Yeah. B.
73:36 19 is intersect that well was No, maybe I think it was
73:41 maybe Shell or Exxon. And it's this one was a gas producer and
73:49 , so this is the the other section. So it's really well
73:54 I've made probably here there are four that I made through here. But
73:59 probably made You know 10 more. mean there's the paper there but I
74:06 to get someone to release that in case. So here's the topography showing
74:12 showing the contours the ice pack of of the flood assault unit and here's
74:19 bouquet gravity. So finally getting some , all that background material and it's
74:24 big gravity high this is a big high over a basin. It's a
74:30 broadway that it can mean a lot things. It could be crustal,
74:37 could also be what else It could crossed also what else could it
74:51 What is the density of the It's um Oh my gosh. Very
75:02 don't think I asked you to. it's it's the density of the salt
75:07 like the density of ocean floor. . So in our two D.
75:11 , what was the density of the upper oceanic crust? Oh we didn't
75:16 do that. We don't even do . Never mind. So it's it
75:20 be it should be on the order 2.8. So and when you compare
75:27 with the density of sediments, do have a do you have a sense
75:33 density of sediments? What they would to be. Remember a little exponential
75:37 function? Yeah. It was like . know how far Between there and
75:48 did it go up to? Was like 2.3 or 6? Getting there
75:55 a little a little plot went from to 2.7. So I mean 2.7
76:03 really hot for sedimentary rocks. I give them more like 2.65. But
76:10 basalt are 2.8. So what does mean? Look at that? Look
76:13 the ice pack how thick it is compare the density of basil to the
76:19 of sediments? So just Mhm. mean just that big red area.
76:35 just that's the high density. Well I mean the can too I
76:42 if the assault is constant density it's filling it up. Right. I
76:48 it's just hired. That's that's one . So it could be a
76:53 it could be crossed it could be density contrast of the thick of the
76:58 with dense with sediments. Any other it could be. Is this the
77:07 ? No I said that I say crustal. I mean that's what I
77:14 . Yeah the thickness of the What else could it be? Let's
77:21 Mount Hope salt down. No no out here. It could what would
77:28 think about processing? Okay. What's what is the bouquet correction? Dancing
77:46 ? What is the book? A , density correction density. Remember I
77:55 a big deal. I said it's the same. No matter what.
77:58 though it doesn't make any sense it's the same number. Oh um You
78:05 it's like a legacy data. If bouquet you can back out the bug
78:10 correction and you know what that number gonna be. 2.67 Oh that's granted
78:22 it? That's actually courts but But yeah so. Right that's what we
78:30 think from our from our plots that went through was granted was the average
78:38 or something like that or 2.662.66. got our test here because you answered
78:48 question correctly. 2.66666. So two 67, which is very close to
79:04 , right? Very good, very . Um so what it could be
79:09 you don't remember this is this is topography is flat and it could be
79:17 bug a correction. So it could a lot of things. I
79:23 And how would you figure that What would you do to figure that
79:27 if it was crustal or or if was the contrast with sentiments or if
79:32 was the the bouquet correction, how you figure that out? Couldn't you
79:38 look at your mag data? you just make a model through
79:44 stick in those values and see what . Yeah, you just you just
79:49 a model of that would help you figure it out. That's true of
79:51 lot of things. But now speaking MAg data just here it is now
80:04 is a mess, right? I it's just full of high short
80:08 you know, chatter and that's because the assaults right there at the surface
80:14 near the surface. So you're getting that catches. There are some longer
80:18 though in here that these things are opposed on. Um Now these blues
80:27 reds, they don't bother me that's telling me it's reversed polarized. There's
80:31 some remember all these but here's the that I think is interesting is that
80:37 are a lot of positive anomalies, though the grand run is reversed And
80:43 is 90% of these flood. That's interesting to me. That's really
80:57 I'm gonna send, I'm gonna send note with friends of mine because I'm
81:05 send a note. Terrific blakely about . He's done a lot of work
81:12 here. Um Okay, anyways, , right, so um yeah,
81:34 you're looking at here is just very way. I think its surface
81:37 Um we can look at that Um Again, this this is,
81:45 some blake, here's some map from work here. Both of these are
81:50 he's showing um, gravity anomalies here , different color scheme. And he's
81:58 some modeling in here and here's zooming here that the Yakima fold, Yakima
82:06 belt. I know that. I , I don't know what T stands
82:10 , but it's all these little lines outlines of the Yakima fold belt and
82:18 see them here again. So, the Columbia River, Columbia River over
82:23 is um it's right here is right , Columbia Washington. I don't,
82:40 , can't find a ripper doesn't haven't in, but it has to
82:45 oh, there it is, right . There's a Columbia river right
82:48 Um but you can see those four in the magnet. Look at
82:52 a lot of these lines are lining up with the full belt here.
82:56 are there now, blood vessels. liquid right there. They have a
83:07 , low viscosity they flow. So in the world is producing these these
83:16 lines. These are all structural. big fools, big declines in the
83:22 of this, of this, of basin, of the of the on
83:26 of the plateau here, there's many them. Um Let's see where are
83:32 at? He's modeled some of Like this line here goes right through
83:37 . He's modeled some of these Um What in the world are
83:45 We're gonna look at that in a . But I think I got another
83:48 study here by withers. Withers. . Um he's saying there's an unexplored
83:55 tectonic basin just to the south So here's one of these big giant
84:05 uh falls here right here. And one of these folds up here.
84:13 see this is the blue mountain and . It's one of these basalt
84:18 Let's see cemetery rocks and the site yeah, right. Columbia River.
84:30 , I see. Everything is Columbia basalt except was recorded at the city's
84:35 . Okay. Um so, uh says that he did some gravity modeling
84:47 Dave actually. So this is a data showing the the uh the base
84:52 the basalt right here. And he that it's prospective beneath it.
84:57 I guess, I think I'm just you this. Oh, yeah,
85:01 . And then this is where he the models. So, this model
85:04 is right here going from northwest to . And it's right, you
85:11 it's right on the flank of this basalt thickness. And here's here's the
85:17 model right here. There's three different of the same model where he has
85:23 , which is, that's Columbia river , which is just thick bit
85:29 And then um, then he has other john day and clerical and the
85:40 , the hair and are the different , these are page in sediment
85:46 So he's thinking that there's a there's basin in here based on this
85:51 Yeah. So, okay, let get back to this part again because
85:58 a question I want to ask You have all these assaults, these
86:04 lines that have formed on top of basin, on top of the
86:08 And the here, this is really good figure in the Yakima fold belt
86:16 . Um, but the salts they don't like make an declines.
86:24 these these antique lines are actually, know, growing today. In
86:33 I stomped up on one of We pulled over, I went right
86:37 on one because there was some beautiful columnar assault blocks. And I had
86:43 . I had one of lining one the beds in the backyard. I
86:46 up with a suitcase that weighed £28 came back with the same suitcase laying
86:52 £50. So I took a big giant from up there um in any
86:58 Um uh uh what do you think causing these things to, what's causing
87:09 folds? I mean they're growing today right out who used to be a
87:14 up there at this university up in . I was talking to him about
87:19 and he told me that. he said that they're growing like
87:22 a few centimeters a year or something that. I mean something, some
87:27 that's actually measurable. So what in world do you think is causing
87:37 Could it be um I don't want say like a hot spot, but
87:43 like still erupting underneath or something causing to uplift. Well you're thinking in
87:48 right direction. So let's think about another way. Do you remember that
87:53 show you a, did I show a heat flow as a function of
88:00 age plot? Didn't I show you ? Or did maybe I didn't.
88:04 don't know. I believe so. . So what's the time frame on
88:09 flow is a function of age. drops quickly over the first how many
88:22 ? I mean, it flattens its log rhythmic, right? It
88:25 drops and then it just flattened, plateaus out. I don't remember the
88:34 off the top of my head about million years. So if you go
88:39 to this mid atlantic ridge is and met there their depth as a function
88:46 age? They all flattened out 20 40 million years. When did
88:55 when did these eruptions happen? What I say? You said these eruptions
89:10 ? No, that was the I'm just looking for one.
89:19 sorry, You have it on the . Okay. Yeah. 16 -
89:30 . They're my C. Okay. . So 16, 17 million years
89:37 . Where would that be on that of of the ocean cooling? They
89:46 still have a lot of cooling to , wouldn't they? Like in the
89:50 ? Not even Right. I I think these are from cooling.
89:58 think their wrinkles, some people have to say that they're from some sort
90:05 structuring, but they're they're all different this way this way. This
90:11 they're all different directions. I think are wrinkles on the, around the
90:17 , the basin is still subsiding and wrinkles and and that's and that's why
90:22 still growing. Hmm. Some people like that idea a lot because they're
90:31 invested in other ideas, but but mean, I'm just thinking, I
90:35 , you look at their different What in the world's wonder what's causing
90:39 ? You know? I mean, me it's just Yeah, Anyways
90:44 that's enough. We can take a . It's 2 43. You want
90:48 come back at three o'clock. Alright, Okay, so The last
91:02 . this is going to be gravity and hate flow thermal properties. This
91:07 kind of like he follows still a field. So I mean it's all
91:13 fields. This is extra stuff this I haven't taught before so we'll see
91:19 it goes. Um I think what gonna do is I'm gonna start with
91:26 flow and then go back to gravity and then I might end up just
91:32 the time to introduce gravity gradients. you understand conceptually what's going on because
91:38 went through those slides this morning and there's just a lot of lot of
91:42 histories and a lot of high highly stuff and I don't know if we
91:49 I don't really know if yeah maybe can just uh maybe I'll just start
91:56 the heat flow. Um Where's that ? Here we go. Yeah I'll
92:06 with heat flow and thermal profit. is stuff I've been actually working
92:12 I don't know if you know I a presentation that the experience of field
92:17 last month a couple weeks ago and I made I'm making one next week
92:21 the G. S. H. luncheon. Uh Same material, it's
92:26 be heat flow and and uh machine predicting heat flow. So f.
92:36 . I. That's going to be Wednesday. It's gonna be online too
92:40 you can watch it. Are you member of the local societies Geophysical geological
92:47 I believe so I don't I think needed a new my membership, it's
92:50 up but yeah it's always it's a idea to be a member of you
92:56 , a couple whatever international groups like S E G A P.
93:00 But also your local ones, the . S. H. And the
93:03 G. S. Because you know in Houston because you know you get
93:07 good quality presentations, there's no shortage material being being presented. I mean
93:15 you look at like the the if like the calendars for like the Permian
93:21 or the Dallas Geophysical Society, there's on it. I mean they got
93:25 planned. So it's the Houston is very societies are very active because there's
93:31 many people obviously anyways. Yeah, a good idea to to to to
93:38 those things and check it out Okay, so heat flow definitions,
93:43 flow, the formula of heat this is called Four Years Law.
93:49 it's just basically the it's the thermal D. T. D.
93:55 Or in this case dy but for we think in terms of up and
94:00 time and it's just scaled by the conductivity. So heat flow is flux
94:06 like gravity field or a magnetic field It's it's the the units are mila
94:12 per meter squared so that is Um And thermal conductivity is a linear
94:20 . It's just a measurement. It's the right here. I wrote it
94:24 the rate of temperature increase within the as a function of depth. In
94:28 words, I'm sorry. That's the conductivity is down here. Yeah,
94:32 just a Iraq's ability to trance trance transport thermal energy. Right? And
94:40 just it's what's per meter kelvin is unit. I don't have them
94:47 So he follows something to thermal gradient by thermal conductivity, right? Hate
94:54 . Production in in the earth is associated with crystal and rocks in the
95:02 continental crust. Because it's old, still a lot of radioactive elements like
95:08 and potassium and thorium. And as decay, they produce heat. So
95:14 heat production. Oceanic crust is thought to be is not to be able
95:23 produce heat because it's you know, recycled. There's no it's it's the
95:27 they use to describe oceanic crust is , depleted in radia genic sources,
95:34 other words, radio developments. So , and this is why oil and
95:40 . People who explore for oil and , I don't like to be on
95:44 of oceanic crust because they don't think there's one, I don't think there's
95:49 source rock on it. And to don't think there's any heat source or
95:54 any heat, there's background heat coming from every part of the planet.
96:00 ? But there's but there's but for you get background heat also called reduced
96:10 plus radio genic heat. So heat is a knot and then d is
96:17 thickness of the heat producing layer. is not really, it's the thickness
96:26 the layer, I think. So is written um by his chief and
96:33 the folks that do this heat production , they're always working at outcropping
96:38 So they have what they call the depth of of the characteristics depth of
96:48 heat producing layer. In other words standing on the top of it because
96:54 working on an outcrop, then you , the bottom of that is actually
97:00 . Which is the thickness of but for a basin you're not standing
97:06 it. So it's actually the thickness the heat producing layer, not the
97:11 of the basement. So that's a it's a little, it's a little
97:16 , a little wrong. They're basically is the thickness of the heat producing
97:22 and anna is heat production. Um , so what you measure over continents
97:31 the background heat flow plus the heat just over ocean, we just have
97:36 one variable. Okay. And what chapman found was that um from a
97:44 study That the background heat flow is , the signal um 3/5 of the
97:52 flow. And that means that the produced by radojevic sources, it's two
98:02 . Okay, so yeah, this just the units again, mila watts
98:06 meter squared, which is flux heat is micro watts per square meter.
98:13 note that if you go back to equation here, this is, this
98:17 volumetric for cubic meter, but this distance in terms of meters for
98:23 So that means the meters cancel And the second term is flux.
98:30 , watch premier covenants, linear. . Alright. So I was explaining
98:37 about heat production and how it's So this is a really nice
98:41 how that formula works that in By the way this formula down
98:46 this is what I'm calling equation That is a empirical formula and it
98:53 that was discovered given a credit to guys named Birch and others in 1968
99:04 some obscure journal. Not, I a book. It was in a
99:08 of the book. Okay, So how it works. They go out
99:13 to an outcrop, several outcrops in in a whatever zone or a particular
99:21 that sort of uniform. And they a device that measures its heat
99:27 It probably some kind of a Geiger that measures radioactive decay. And then
99:33 do some math and figure out what heat production value is according in terms
99:38 micro watts per cubic meter. And they plot that for each terrain plus
99:45 error bars. And then they also heat flow. So they have some
99:51 drill down a little hole and they a unit and they measure, you
99:56 , they measure temperature in two places then they measure that depth and then
100:02 measured thermal conductivity. And so they heat flow. Okay, so they
100:07 heat flow in the same location as sample from the production with the error
100:13 on that. So what you're looking is all these different these seven different
100:17 is plotted with error bars. So once you do that, you can
100:24 that you can find the best fit line through those. And and that
100:31 line. The slope of that regression that is D. Oh, that
100:40 D. D. Is the slope the regression line. And it's also
100:44 thickness of the heat producing layer. where that intercepts the intersects the
100:54 the y intercept that is Q. the background heat flow. So background
101:01 flow is here. And then you D. Which is that. And
101:10 have the heat production values. And you you can satisfy that equation and
101:18 equation. So that's how that So this is a little figure
101:22 this is what I was talking about . You have background heat flow,
101:26 is everywhere. And it's from comes from beneath the little sphere. And
101:33 you have heat flow that's produced by continental crust from radioactive decay. So
101:40 little cross section here shows a passive , you know, ocean basin,
101:46 margin, rift basin, continental upper and lower and then the upper
101:51 is kind of shaded black. And also showing it. And of course
101:56 mojo, which is the basic I'm also showing you to temperature horizons
102:03 dashed lines. So the look of dance your boundary which is called the
102:07 . A. B. And the point depth. Those are both temperature
102:12 so they can be found in But they also have a temperature associated
102:17 them. For the L. B. It's thought to be about
102:20 30 degrees. Kingery Carry point is temperature at which rocks gain or lose
102:29 magnetization. Alright so and in this 580. That's for magnetite. So
102:38 , if you're heating it up once hits 580° it will no longer be
102:44 . And once it cools back down 500° it will become magnetic. So
102:53 remember we did death to source So we can map the basement surface
102:59 magnetic anomaly. We can also map key point depth from magnetic anomaly
103:08 Key point is thought to be produced the very longest wavelengths um in the
103:15 after after of course it's core corrected you remove the I. G.
103:19 . F. Dead. And so then of course we learned about depth
103:25 estimation. And so the basement. this magnetic layer is um is where
103:35 continents is where you have radios being from. So we actually see what
103:47 this say. This says the remaining makes use of magnetic Permian basin.
103:52 we did a study uh me and colleague and uh beneath the premium for
103:58 Permian basin. We we did a of uh magnetic layer and tried to
104:05 determine different thermal parameters, thermal So the idea is of course we
104:14 to use debate the curie point death of the L A. B.
104:18 it's, you can map it with data. We mapped a near surface
104:24 using open file borehole temperatures and then define pre temperature horizons, the near
104:34 temperature and the temperature at the basement . And then of course, we
104:40 the Cherry Point Championship. And then those three temperature horizons, we congratulate
104:47 thermal gradients between those and other thermal . So let me just work through
104:53 and I'll show you what I'm talking . So, again, here is
104:55 Permian basin. As we've seen This is the topography, here's the
105:02 basin, the middle air base in basin platform. This is whatever the
105:07 arts, the Val verde basin and Marathon or genic bill. Now,
105:14 is um heat flow stations, these circles, there's some thermal conductivity
105:21 these green and yellow circles and there's heat production stations down here in the
105:27 plus sides, there's a basement So the basement ranges, you
105:35 uh over over a kilometer deep. sorry, it goes from a kilometer
105:41 over six km deep, which is right most most remember most platonic basins
105:48 only about maybe seven km deep You can really see the shape of
105:52 base in here too. Um and here's the, oh sorry, So
106:00 the basement with contours and here's the without country. It's okay. And
106:06 heat flow. Miller asked for me square uh just credit up those stations
106:15 then here's another review of what we for years. Law. This is
106:21 equation, this is the empirical equation birch and this is the relationship of
106:29 and chapman. Now there are two sources, there is heat flow heat
106:38 sourced from deep in the earth beneath little sphere. And there's heat that
106:44 in the crystalline rocks. But but been recognized for a while that there's
106:49 heat produced um in the sentiments, for example, if you have some
106:58 , these are all plastics by the . So if you have some classics
107:02 are eroded from them from nearby mountain , like in a foreland basin,
107:08 may, they're probably not going to well sorted. You might have minerals
107:13 in there that include uranium and thorium potassium elements. So you can have
107:21 flow in particularly plastic rocks in cemetery . This is understood. It's very
107:27 though, right? So, so folks sushi and others Developed five different
107:37 based on heat production values of ranging from 0.5 to 1.5 micro watts
107:45 cubic meter. Um And this is they plot. Uh here's here's how
107:53 well, using these calculating these they can they can also calculate heat
108:03 as a function of base and Okay, so this is the heat
108:08 versus the thickness of the base. you can see they range from,
108:15 know, for the deepest part for kilometer basin, deep kilometer basin,
108:19 is very, very thick Up to million square. But really, what
108:26 are we in? We're in a of around here. Most platonic bases
108:30 around here. So now we're down less than 10 million watts. So
108:35 can see it's not a lot. in fact, the Permian basin,
108:39 use function three just because it's in middle Permian Basin is about seven kilometers
108:47 . So right about here. And means it's about a maximum of adding
108:53 million watts per meter cube. what does that look like?
108:56 here's the range of heat flow. flow goes from basically, you
109:03 uh let me see, we're in in the light, the greens,
109:08 goes from about 35 to almost 100 this thing. Well, six million
109:17 premiere six. gonna watch per meter , is not really that much,
109:24 it? So, anyways, it's correction that we made. Um here's
109:29 station data and this is um the of right, okay, so that's
109:36 correction that we make. And the thing is to make the near surface
109:39 . Right So we take the well's take the well depth. This is
109:45 the T. D. S. you can calculate the temperature at the
109:49 that I mean you are calculated it's . So the wells have all these
109:56 have temperatures and they measured the heat as well. Okay so there's their
110:03 there's the temperature of the wells. then we can between those temperatures and
110:11 service temperatures which have been measured by is the University of Delaware. They've
110:18 25 well they have they have terrestrial temperature for for the Earth Monthly going
110:29 to 1900. So what I did I just took this two standard deviations
110:36 this for the date range, the , the range of the dates that
110:41 wells were drilled on And just took averages and that's what you're looking at
110:47 . So over the premium basis as can imagine, it's not very much
110:52 . This whole thing goes is about So it's not a lot but the
110:58 interpretation between this and and and the temperatures gives you this. So this
111:07 the near surface temperature at 100 m the surface and it goes from about
111:12 to 20. So it's about seven . So the reason I'm doing
111:16 I want to establish a temperature horizon a near surface temperature rise and then
111:21 can calculate the thermal gradient from there to the basement. Now the reason
111:27 picked 100 m depth was because I to capture as many of these wells
111:31 I could. Some of them are very deep. Okay now I didn't
111:36 very much very many thermal conductivity I have since discovered there's a lot
111:41 so this this this study needs to updated but it doesn't really matter for
111:48 what I'm talking about right now. ideas are all the same.
111:54 so here is the radio genic heat in the basin, that correction that
112:00 made for the basin heat flow. here's the basement temperature. So this
112:07 at the at the stations I can forays law because they have where's my
112:14 sir, I have near surface temperature at the stations that I have you
112:21 he for all the stations and I thermal conductivity and I know the death
112:28 the to the surface as well as basement. So rearranging four years
112:32 I can calculate the temperature of the . That's what I've done here.
112:40 let me see where I'm at Yeah. So right so I have
112:45 temperature horizons. I can calculate thermal now because I have these three
112:50 I can calculate the gradient between the service in the basement and the basement
112:55 three point which again is the magnetic . What I'm calling the magnetic layer
113:03 . Uh Yeah. So we have too, which is basically the total
113:08 flows equal to reduce plus that crystal sources. We have the two empirical
113:15 Park and chapman. Um Yeah, therefore the basic background he follows .6
113:26 the measure minus the correction from the . Right. And thermal conductivity of
113:32 basement. So we can calculate the conductivity of the magnetic layer, recognizing
113:38 if you know the background heat flow the base and then we know it
113:41 . So we can rearrange forays law and thermal conductivity of the magnetic layer
113:48 the from the basement to the So here's security Point depth And there's
113:59 thermal gradient calculated by rearranging four years . So the format here is what
114:05 doing is I have some I have text blocks where I explain everything what
114:12 going to be doing. And then So the workflow one here, I
114:17 this text block and it tells near temperature based on thermal conductivity based on
114:23 flow of energetic sources, based on . So, I worked through all
114:28 , there's two stations, there's the borehole temperature depths for cold temperatures.
114:38 is the borehole depth. This is borough temperatures, service temperature, average
114:43 temperature. And then interpolated between the and the surface, the thermal conductivity
114:51 regional source. Then he flow from basin, the basement temperature. So
114:56 I go to work flow too. we take those three temperature horizons.
115:01 can calculate the thermal gradients and then calculate calculate the uh the background heat
115:12 that will calculate thermal conductivity in the . So that's what these next
115:16 A Series of slides are. Key depth thermal be great at the base
115:22 the thermal grading of the magnetic The heat heat flow from the
115:28 This is 3/5 of the total. . And then the thermal conductivity of
115:32 magnetic layer. So all those steps follow. And then then we're looking
115:39 basement terrain. So this is a interpretation by Whitmire, Whitmire and Castro
115:54 Geo Sphere 2007. And what they was they combined a bunch of outcrop
116:00 and um well penetrations to crystalline And they used magnetic data as well
116:09 map all these boundaries so that the and these light pink and these oranges
116:15 here in the northern part. Those all our key and rocks with the
116:19 part in these. And then the ones to the south. These are
116:25 protozoa Going from I think 1.76. the Riley? One point So I
116:36 it's 1.76 but one point seven should in there. You have applies as
116:43 in any case these are successive accretions juvenile crust onto the court is our
116:52 and core of Lorenza. So remember key in time Is 2.5 gigi
117:00 2.5 billion years and older proto resort . The Protozoa Eon lasted from 532
117:10 years ago to 2.5 gig. So like a two billion year. You
117:15 , it's five, it's five times long of a time from the earliest
117:23 or so. Yeah. And so are, these represent five accretion.
117:31 mean, I'm sorry, juvenile accretions the Yama pie, which is this
117:37 wedge here, the which is this one here And the olive colored here
117:44 the granite Riley and then the reds to the outward, Those are Grenville
117:53 out of the other ones. And with those were some granite IQ
117:59 Granite toys is what they call them what what what college would call.
118:04 those are the light greens, the blues and some of these dark greens
118:08 so they, they were intruded at same time. These, these uh
118:17 IQ collisions were occurring but also later those. So these basement to reigns
118:26 radio genic elements in them. They , you know, uranium and thorium
118:30 . So they have radioactive elements in . So yeah, here's the,
118:35 the big terrain here. Um I'm not sure. Oh yes,
118:41 have a pie for this area. just have sell um, granite rye
118:48 and Grenville and the bright greens in . The granite intrusions. So our
118:53 area, the premium basin is right . And we also have the this
118:58 intrusion. There's a well that was in into the central basin platform.
119:09 uh right, so all these terrains mapped and then uh interpreted. So
119:17 so we integrated those uh we're costumes map with the magnetic susceptibility and version
119:26 believe. Yeah. So here's the field, here's the susceptibilities. So
119:32 that's a that is a that's a a linear inversion. Remember we talked
119:38 inversion modeling inversion. So this so total fuel anomalies here were inverted um
119:49 magnetic susceptibility for the rock property. structurally but for the right property.
119:57 . And then this basement terrain map made. Yeah. And this kind
120:15 shows you uh what that looks So here you can see these terrain
120:23 that are interpreted. Remember some of things were I mean There were three
120:30 that three elements uh tools I guess were used to map the terrain.
120:37 had they had some outcrops, they some well penetration and then they used
120:42 data to kind of like connect the . So remember this is the abilene
120:47 from Zhang's paper which also had a anomaly over it. Um and you
120:55 see these outlines here, they are together. So I'm overlaying the trains
121:00 top the susceptibilities. And you can what I'm tracing here. Right?
121:08 why am I doing this? I'm this because we have heat production
121:12 Remember that? We have those We have them for the world.
121:16 the idea is to assign heat production to each of these polygons. And
121:25 use that with that. Remember we that empirical formula which has the total
121:31 . The total heat flow is the of the background heat flow plus the
121:37 flow produced by these terrain. And heat club is the product of the
121:47 production of the trains with how thick layer is. So this is a
121:53 thickness that hangs off the basement. if you can visualize we have a
121:58 layer of sedimentary rocks, we have layer beneath that that we're calling the
122:04 layer which extends from the basement down the key point. So in our
122:10 layer model right we go from the surface to basement to carry in our
122:14 layer model. We have different rock . We have we have we have
122:19 temperature of the horizons. We have heat flow within each layer and we
122:24 the thermal conductivity with each layer. in addition in the basement we also
122:29 heat production but that heat production within magnetic layer basement to Kerry point there
122:40 it is subdivided bye whatever thickness this production layer is. We know that
122:48 heat is produced in the magnetic layer we don't know where it is.
122:53 don't know that until we examine the production data. So that makes sense
123:00 you. Is that really confusing? a little confused. But it makes
123:06 . Like it's like okay. So , I'm sorry but you know I've
123:11 presenting this material and my presentations have over time but I prepared this last
123:19 and I've been doing this work. let me just let me just quickly
123:24 everything because now that I look, breezed through these this morning. I
123:28 I understood that. So okay, this is how peak production and this
123:34 you know, we have these basic , right? We have the basic
123:39 flow equation which is forays law which very simple. It's just the thermal
123:46 D. T. D. Scaled by the thermal conductivity. That's
123:51 simple. Then we have this other which is empirical which is says that
123:57 you measure over continents is the is some of the background heat flow plus
124:04 heat flow coming from radioactive decay in basement rocks. And that heat flow
124:11 the product of heat production times the of that heat producing layer. So
124:18 I look at my little cross section horizons are we have a near surface
124:24 which basically tracks the topography here. we have a then we have a
124:30 horizon, right? And then we a query point. So we're really
124:35 looking at the near surface the basement the curie point. But when we're
124:42 about the heat production separately, there's another layer that hangs off this,
124:48 we don't really know what it is we go through a bunch of
124:52 Because even though we know the ridge flow exists in this layer in the
124:58 layer, we don't know what its is. That distribution is is is
125:06 by the product of how many you what the heat production is, how
125:13 how concentrated the radioactive decay is and thick that layer of radioactive decay
125:20 Right? So there's a there's a in here that that is a heat
125:27 layer. So that is that is that that Yeah. Right.
125:33 So this is a bit a sunrise kind of explains all that's gonna
125:39 So then I show you the topography then the station data, right?
125:44 have three kinds of stations. We uh heat flow, thermal conductivity and
125:49 production. Now this I sample an much larger than this. Um and
125:56 we have, of course, the surface is just topography minus 100
126:01 The the the basement. Is this by uh Rupel from 2009.
126:11 And so we have the measure heat a grid of that. And I'm
126:15 the same color scale for all the flow maps. It's a linear color
126:21 . That's why this one starts up around 35 because I have the near
126:28 , I mean the basin heat Okay. And then I'm repeating again
126:33 equations, So I'm starting into this for this example. So it was
126:38 days law that the birch uh empirical here and then follow chapman's empirical study
126:48 the world, where they found that each of these are 3/5 and 2/5
126:54 what's measured on average, on And then we make this little correction
127:01 heat flow that he that's produced is in the basin. It's a tiny
127:09 and it might not be necessary, we're doing it anyways. So we
127:13 that. Okay, so again, here's developing the near surface horizon,
127:21 the stations, there's the depth, the temperature at those depths. Then
127:28 have the very surface terrestrial temperature. there's what that is averaged over
127:35 you know, the range of well . Well, the days of wells
127:40 drilled down and then here's the linear from the borehole temperatures to the surface
127:47 . So now I have a surface um a near surface temperature in depth
127:56 temperature. Right? So here's the conductivity of the basin, here's the
128:02 flow produced by cemetery rocks in the and here's the basement temperature. And
128:10 I went through another set. So looked at the temperature horizons and since
128:15 have three horizons, we have two gradients, the gradient between their service
128:20 basement, the gradient between basement and point. And we can calculate background
128:26 flow using equation two and correcting it Paul Chapman. And then we're saying
128:32 you know the background heat flow in basin then we know it everywhere.
128:38 can do that. Then we can the film gradient In the magnetic later
128:44 just using equation one again. So through all those all those things,
128:50 security point tap, here's the thermal of the basin democratic and the magnetic
128:58 Background Heat Flow. This is 3/5 the total and then through the conductivity
129:03 magnetic. Later then we're looking at deeper into the basement terrain. So
129:10 can map those basement terrain. And just using already work that was already
129:17 . You can download these shape files the internet and um they spent a
129:23 of time mapping mapping the. Well least the protest. I don't there
129:28 be more detail up here but I know why um In any case these
129:32 the trains in in our area the granite, right? Like the
129:38 All created all the created in the resort. You know all created uh
129:45 500 million years before paleozoic time. yeah. Um And then here is
129:54 basement terrain. This is a total . I can totally feel unique
130:01 Total magnetic intensity in that one. we wanted Do a three d.
130:07 of those. A three D. for magnetic susceptibilities. Remember that's a
130:14 relation and a linear inversion and that's that looks like. So the magnetic
130:22 range here from about pleasure minus 3000 CGs units. Which is pretty
130:29 Okay so Do a three D magnetic and version of the total fuel
130:40 And now we use that with the from what Mark Whitmire and Kallstrom to
130:50 make our final interpretation of the basement . And yeah I mean it looks
130:57 good I think. Um Yeah. so workflow # three We have basement
131:08 . We have heat flow from regional production and then we can figure out
131:16 the heat production layer thicknesses. So the heat flow from raging sources.
131:22 is two fists of the total and the heat production layer thickness and that's
131:33 in the workflow. Yeah. So and this sort of shows a summary
131:38 that thermal conductivity from stations heat flow the basin. We raging sources in
131:46 basin that sushi. Then we used one for the first time to calculate
131:52 temperature then thermal gradient basement to surface a thermal gradient curie point to
132:01 Then using Polident chapman background heat Then we used the background heat flow
132:06 calculate from the conductivity in the magnetic then we then we interpreted basement trains
132:14 we integrated the public data with our susceptibility inversion. Then we used it
132:21 to get the heat flow produced by sources. And then finally, we
132:27 it empirical equation to to captivate the of producing later. You have any
132:42 with that? No. What did do have? Just the image question
132:54 slide. Go ahead. I'm trying find this slide. I was I
133:03 , just page through, did you passing already? It's 73. What
133:12 causing those like um like towards the of the map, Like those two
133:18 right there. Like what are, are those there? Hmm. I'm
133:24 curious. Well, okay, I , so this is the thermal gradient
133:29 the basin. Right. This is thermal gradient from the basement to the
133:36 the near surface. And um that's good question. I don't know what
133:41 causing it. So, let's just at the oh, look at
133:44 So this is the basement temperature. there's let's let's look at the basement
133:55 . Ah, okay. So the , I mean, I think the
134:04 elements to to this thermal modeling are geometries, the geometries and the temperatures
134:14 the, of the near surface. basement in the curie point. And
134:19 you think about that kind of makes , right. I mean, because
134:23 their properties are what control the heat . So, you see here,
134:28 isn't, this is called, I Arizona arch. So this is these
134:32 structural highs and if we look so he club, you really
134:40 This is the thing about heat It doesn't, it does not correlate
134:43 the base and depth as you can . It doesn't correlate at all.
134:49 what does correlate with invasive death? Does the near surface temperature? Not
134:59 um thermal conductivity? No. Now heat flow from raging sources, it
135:08 correlate, but it has to because because this dysfunction, our correction is
135:18 function of basic things. So it's , you know, it's no surprise
135:24 the this this little correction we which is tiny. Right? I
135:29 , it's not even, it's just few million watts per meter squared.
135:33 we can really discount this. But at the basement temperature is strongly
135:41 And how do we do this with temperature is calculated by rearranging for law
135:49 at the stations we have heat we have thermal conductivity and we know
135:55 depths to the, you know, know, you know, disease to
136:00 basement. And the only thing we have, we only have one of
136:04 temperatures we have the temperature of the surface. So we can rearrange all
136:10 that. Right. Let me just just go back to the formula trying
136:22 see do I have it in Okay. To use So at the
136:31 we have Q. We have We have Dy DZ this case DY
136:38 And we only have one t. have the temp the near surface
136:42 So we can we can arrange that to calculate temperature of the basement by
136:56 rearranging that formula. And that's where are coming from. Those highs are
137:07 , which makes sense. Right? temperatures go up as a basement as
137:11 , as the basins get deeper, ? Or thicker. Right.
137:17 So that's where those are coming Oh, okay. Yeah, that's
137:23 . Yeah, that's where those are from. Because because if if the
137:33 about it, you have the heat is not only the same throughout
137:38 And the throne conductivity is as So what's controlling this is is the
137:46 ? The basin, the basin is basic temperature here, temperature is
137:55 So the tea is low but in thickness is small. That means you
138:02 to have high gradient to produce the heat flow. It's just a trade
138:08 . Mhm. It's really pretty. mean, Yeah, Yeah.
138:22 ask me questions on this if you later. I mean, I'm not
138:26 what I'm gonna do. I might test you on anything in these things
138:30 the slides are not obviously, I to do some work on these
138:35 So, I might ask you a of general questions that are in the
138:39 . But yeah, I won't blame for being a little confused. This
138:45 new material for me. In this is when I presented this,
138:49 presented this this work, not these , but I presented this work like
138:56 from the Denver Jill's berg and potter basins at the image conference last
139:03 And and yeah, and I've been I said I've got other presents.
139:11 new stuff that I'm trying to, to do. What I did was
139:16 my cover on my title slide, slapped across it what I did on
139:22 pandemic vacation because this is material. is all stuff that I that I
139:29 um in 2020, 2021. So , anyways because you know the industry
139:38 changing a lot and there may be geothermal opportunities and anyways. Yeah,
139:44 I'll just, I might ask you basic stuff out of here but not
139:48 , nothing that you have to, know, be too concerned. Probably
139:53 other stuff to the great allergy stuff well. I didn't used to teach
139:57 stuff, so you're getting new new . Um Yeah, so such as
140:03 is so um if you want, we take a take 10, come
140:11 at four and I'll finish up with at least introducing the gradient stuff.
140:20 . Okay. Alright let's just finish up and celebrate. Okay, so
140:29 this is more new material. Um gravity gradients um and no they do
140:40 do collect magnetic grades but it's just just, what they do is they
140:45 fly uh with like two stingers where airplane would have one sting and have
140:52 right below it. So they just a physical measurement of the field and
140:57 locations. And then their difference is , is the gradient, is the
141:04 gradient. You can do that horizontally they put stickers on the wings and
141:10 they measured the, you know, magnetic, you know, than just
141:14 to those across the wings and you a horizontal grade or whatever. So
141:21 done. Um gravity graders can be that way as well. I
141:25 you could you could just measure gravity two different elevations and their difference would
141:30 the great the, you know, grading of the field. Right?
141:34 there's there are instruments. In the very first measurements of gravity were
141:41 instruments back in the, You 19,000,000 Early 1900 1910, 1920.
141:50 that. The cost of Romberg Instrument developed until 1930. So yeah,
141:59 so gravity and magnetic data are acquired measured in quantities. Uh What they
142:06 are the fields of course, write vector fields and those can be expressed
142:11 in Cartesian X, Y. Components. Now, when now the
142:17 commonly, what we what we Okay, let me go back
142:21 Standard values how many good contour maps scalar is right. So when we
142:26 at all the anomaly maps we've been at are basically the scalar of the
142:32 field values. We're not, we're getting any vector information criminals Right?
142:37 mean, nothing is telling us what direction of the vector is. We're
142:40 looking at the, you know, the the amplitude, so to
142:47 But in some cases the actual components measured of the vector field. For
142:54 , flux gate instruments measure the components the magnetic field. Okay. And
143:02 are geodetic instruments. Remember we talked land measurements of the ge Oid?
143:08 actually measure the deflection of the gravity relative to vertical relative to, you
143:15 , steroid. So if you want think about the whole idea the whole
143:26 you know mathematically from from potential to . Right? We have force
143:35 The force fields are the drifters or of potential and the gradients are the
143:42 of of the force fields. and then inverse mathematically integration. You
143:48 go backwards from gradient field to So I made this little table
143:56 We have the field, the type quantity and then math direction of math
144:07 derivative versus integral. Right. So field um it's it's derivative as a
144:15 field. It's driven a gradient A scalar to vector two tensor.
144:24 ? So that's just kind of a that way. I think of
144:26 And I imagine a mathematician might tell there's some problems with this, but
144:31 just think it's convenient to sort of them that way. Okay, so
144:37 data. What is the earth's gravity effective fuel with xy components. Thank
144:43 . The grading field consists of excellent for each X. Y. Field
144:50 . So no these could say I'm T here but I can say G
144:57 as well. Okay so T X Y T. Z. Are the
145:02 components of the gravity field and then . X. T. X.
145:05 . T. X. E. . Yeah these break down into three
145:10 each of these right now there's some because fields are conservative, you know
145:20 Illinois elite center it center that supply plot. They satisfy the plaza's
145:25 There's symmetric about along this axis X. X. Y.
145:31 Z. Z. That means X. Z. Is equal to
145:35 . X. Y. Z. . And so forth. Okay so
145:41 kind of a visual way to think it. How how do we measure
145:46 ? Um They have these instruments basically accelerometers and So the gradient of the
145:55 Chicago by subtracting the measured field values pairs of accelerometers monitor opposite each other
146:02 spinning disk. Right? They have for the F. T.
146:07 Instrument. There's three spinning discs and all inclined. And so each opposite
146:17 of measurements so each measuring the gravity . That means their their difference is
146:25 gradient. And these little things are called G. I. S.
146:33 This paper from 1988 um gravity gradient survey system. This is this shows
146:41 little G. I. S. and vertical. So the gravity great
146:47 survey system G. S. Was in the late 19 sixties this is
146:53 a military thing, like lots of . It's either developed most of our
146:58 is either developed in the military by government Nasa or D. O.
147:04 . Or in universities. Very few actually generate new technology. Um So
147:15 gravity grading amateur, I'm reading this block down here theoretically is insensitive to
147:22 accelerations since it measures the difference in . Okay right. Just a little
147:30 . Um So this is the the of the first instruments Grady after instruments
147:37 it was this enclosed box and this this is development Bell Aerospace and now
147:45 spin off from the Bellagio space which the F. T. G.
147:51 . Okay. Um and the platforms that are the dynamic platforms. I
147:59 they have, you can measure you on the bench or on land if
148:04 like but there are dynamic plant one fixed wing, here's a here's
148:13 this is a Cessna caravan. See B. And D. This is
148:20 you look closely that says bellagio space fly, there's with the Dc
148:25 So they're expensive surveys and then they've there's a lot of the very first
148:30 were marine and then de beers, famous diamond company flew with a
148:38 this is in South Africa, that crashed I don't know crashed two years
148:45 . Um Right so if we have little square prism and we want to
148:53 the gradient, the gradient field over for each of these components. So
148:59 X X Y I'm sorry, this gravity, gravity ingredient components. So
149:11 , X Yeah, X X, X, Y X. Said,
149:15 y y zed said said um this is, this is the shape
149:25 you get. So if you X means um yeah, the gradient is
149:36 for the X component in the X . Okay, so for the X
149:43 component of the field, it's it's the X component of that.
149:51 , and then these two are for Y component and this is for the
149:54 component of the vector. Um in example is a 10 kilometer square
150:03 28 kilometers thick where the top is kilometers down in the desert contrast is
150:09 g per cubic centimeter and here's here's just the gravity signature of
150:16 So the gravity looks quite like Z. Z looks quite like the
150:20 looks like a vertical derivative. No, that's because that's what it
150:26 the vertical component. We know a about we calculate this all the
150:31 Now, what is the conversion from to eat boats? Right, so
150:36 is, there is a conversion, tell you what it is. I
150:47 I had it right here in front me. I don't, I think
150:50 have it in my notes here in in the class notes here. Oh
151:00 . Okay, this is nice. is nice. This is this is
151:06 this parts of this is in wellings on Grady actually. But so if
151:12 take instead of I think I think problem was using a square where the
151:18 the sides are are, you oriented north, south and east west
151:25 china doesn't really help you understand. And that's because these data are processed
151:34 the N E. D. According the N E. D.
151:37 any D stands for Northeast down in words, the gradient is calculated from
151:49 to north west to east and top down N E. D. So
151:57 the direction that the gradient are I mean when you look at data
152:05 data, that's how it's displayed. , this helps make the point.
152:10 let's just look at let's just look X. Said and why is it
152:17 ones that have the arrows and the lines? Those both of those lines
152:25 to this profile with a red red Over this. This model was
152:31 So this is a .1 g per centimeter contrast of this three D
152:37 So this is a this is a deficiency. It's a cavity And the
152:43 with the Cavity of zero. The is .1 and this profile goes from
152:50 to east or south to north here . And you can see when you
152:57 this body from east to west from to east. This is the there's
153:06 there's a minimum of closure directly over edge of the source and a maximum
153:15 over the edge of uh of the side of it. So not only
153:23 this peak and trough does this these anomaly. Men max tell you where
153:31 edge of the sources and it also you which direction is getting uh lower
153:39 or higher density. That's really I mean that's really useful. You
153:44 just make that inference directly from looking these data. And that is something
153:50 until our paper just came out is described in the literature. And it's
153:56 and when I explain these data to , this is the first thing I
154:02 . I go through and say, , this is X x,
154:04 you know, x, Y And Y said blah blah blah,
154:08 these things and explain what they And then I say, you
154:12 this any d standard. And I , let's just look at these two
154:19 I explained what I just explained to that X and Y. Is that
154:25 the most useful components. Now. people say that is because it's,
154:29 know, it's it's looking at, know, it's centers over the mass
154:33 I think there's a really good point that, right? As you look
154:37 here, Z. Z. That they're the same as just regular gravity
154:45 . That's what this is just Z. Right? It's just regular
154:50 data. But those look quite like are quite similar. Right? I
154:55 why did you do that if you that, you don't need to do
154:57 right? You don't need to collect the other components. So why do
155:02 ? And the answer I think is you can map the edges of sources
155:07 from these data. And um I we had a hard time getting that
155:14 published. It was it was in for 16 months because we just couldn't
155:20 to these mathematically biased folks that really think about geology very much that that
155:30 though this is very simple minded, not described and people should should be
155:36 to look at these data and understand . So let's just compare them.
155:41 look at this is this is even is going and the reason I like
155:46 more than the boxes because it's showing it's showing different directions, right?
155:51 . Anything that's generally north styles, ? You can have to be at
155:58 angle, the high will be west the edge will be over the western
156:05 and the low will be over the edge. The high will be over
156:09 eastern edge. Right? Let's look look at this one. Okay.
156:18 know that from this but you don't know it for something that's at an
156:24 . It's just it's not clear. plus this thing is too deep and
156:30 thick. You don't really see That's why I made this one with
156:35 such a small feature so I could see these anomalies. Really isolate
156:41 Anyways, I spent a lot of on it, but I think it's
156:44 , it's really important because this side explains to you how these things work
156:50 the most the two most useful ones X and Y. And if
156:56 you can amaze people, you if you ever see these data asked
157:01 see, let me see Exit a because you'll know that you can match
157:06 from those directly without having to do inversion. And yeah, okay,
157:13 now in version is pretty much the of choice for these data because they
157:18 so complicated and this is just from paper uh and they're just doing
157:23 you know, one of these laminate that we've covered for for just the
157:31 gravity data, it's pretty standard Okay, here is now now there's
157:38 bunch of a bunch of examples So this is a an example from
157:44 and Barbosa and I think this is brazil Oliviera, those sound like Brazilian
157:51 to me. Um We'll see. . It's slide slide 12 oh here
158:15 yeah. Um Yeah, maybe Why am I thinking this anyways?
158:26 , in any case. So they the components here. This this one
158:32 um yeah A. S. X. B. S.
158:38 Y. X. Said why why is it? Okay so here are
158:45 two that we would look at to . Okay going okay so this is
158:53 this one has to be um X. X. X.
159:00 Right? So that means action. can't be right. That can't be
159:11 . I think they're backwards I Yeah this is this is easy.
159:19 is the vertical one. These these but it just has to be
159:24 Said these two are backwards. You make that correction. C.
159:29 And C. And E. Are . In fact A. And
159:37 Are reversed as well. A. to be Y. Y. And
159:42 . Has to be excellent. You why? I know that don't
159:44 Because it's because it's kind of like long strike. They don't change
159:48 Right? Yeah. X. That's where the big changes anyways.
160:01 what do we know? Okay so is going from we go from south
160:05 north. Low density high density. means the low density is north of
160:13 source body. And the high density I mean this this means it's a
160:18 density feature between you because the high gonna be north of the source.
160:28 ? Yeah. The highest north of the the highest north of the low
160:34 source. That's right. That's That's right. This is a
160:41 right? That's so that's what this . This is not simple because it's
160:47 circle. I think that's what's getting messed up here. Yeah.
160:52 it doesn't matter. We're not gonna not gonna worry about that. So
160:58 there are two in, there are two instruments, there's the bell instrument
161:04 really not austin, we can forget those. There's the bell instrument and
161:12 this is what it looks like. it's three inclined spinning disks that are
161:20 in in in this carousel that rotates they each in each one of
161:27 there's an inclined G. I remember with two pairs, so there's six
161:32 of spinning disk in these. And carousel can also rotate with any
161:41 And here's some of the very first that this was donated to University of
161:45 over Vincent dome Louisiana. And this some noisy data. I mean,
161:51 dome is producing this broad, she said, and there's a cap
161:56 over Vincent dome in Louisiana. And just, yeah, this is really
162:03 to look at and this is what FTN are what they call their tensor
162:16 reduction. So on the right, reduced noises, it's reduced, it's
162:21 . But I mean, here's another of their noise reduction. So you
162:28 see it's just just chatter and it's it. It's improved it. But
162:34 don't know, I get the sense , like there's some artifacts that stretching
162:39 stuff. Um Okay now this is . Oh this is a paper I
162:49 this is more F. T. . Noise reduction. Yeah. Method
162:58 use notion. I don't think I'm test you on that. I wouldn't
163:04 you on that. That would be mean of me more sort of filtering
163:10 . So there's there's a whole bunch folks that sit around and think about
163:14 James brewster. He's a really nice and just ridiculously smart. He's that's
163:21 mentioned a lot of these a lot this stuff he works for Belgian
163:29 Okay. Um this is a case . Now some of the tools they
163:36 besides inversion they use what they call variant calculations and invariants are basically um
163:45 of the tents of components. You these. So in variant one um
163:52 this combination of texture components and variant in very zero? Is the traces
164:00 laplace. Um It's del squared. T X X plus two Y Y
164:04 Z. So that's and and there's called. And the reason these I
164:13 through eye to eye not I one two, they're called rotational invariance because
164:20 you once you do these combine the components in this way the data or
164:28 the rotational doesn't matter what direction you at them. The N.
164:31 D. D. N. D. Is is accommodated so there's
164:38 directional about it but what you also with it is you lose that ability
164:44 know which direction is getting lower or , you know high debt to your
164:48 density and then there's this horizontal invariants are independent of just the vertical
164:56 Yeah. So you know, Oh no, I'm just kidding.
165:02 I either to know is that the tools for gradient interpretations are inversion,
165:14 inversion and in various calculations and direct of TXN and T. Y.
165:30 . So right, so here is is this one? This is this
165:37 this Newfoundland study? So they did just study in Newfoundland. I don't
165:43 . We can just look at the TXN T Y Z. So we
165:49 here the highest also. Right. if the high is north of the
165:57 density that means it's south of the density and vice versa. So the
166:02 right in here. Yeah. Yeah. Yeah. Yeah. Same
166:05 here. The source. You can the source so that goes, let
166:09 go back to that when it was was confounding. So. Right.
166:16 . Yeah. Yeah. So it's going to be in here.
166:19 Yeah, I get it. Alright. Um here's some demonstration of
166:26 invariants again. Is this the same ? Yeah this is from the same
166:32 so that they apply to invariants The rotational ones are too. Uh
166:41 . What do they call our-2 and too with the first vertical driven.
166:46 it's the first, yeah The thing gravity gradients gradients it's relatively new.
166:54 mean it's they've only been doing this of work for 20 years or so
167:01 it's the literature I mean there's just ton of literature but it's dominated bye
167:10 my view folks that don't know a of geology that they really they know
167:15 about math and geology because they're geophysicist kinda geophysicists that don't know a
167:23 I mean you know geology I I hate straight lines. I mean I
167:28 think that's where geology is anyways. Yeah here's the last map so they
167:34 some sort of horizontal in various map . So from this from this analysis
167:40 drew these lines. I'm betting you really need to do all this work
167:44 draw these lines. I bet you just draw those lines probably just from
167:48 mag data or just a vertical derivative gravity. That's just my blast more
167:58 variant work with a different Murphy and . So call Murphy and James brewster
168:04 their bellagio space. Um This is state of brazil. Um Maybe this
168:11 what I was thinking of. So did a power spectrum residual. Remember
168:15 talked about those on the T. . Z. Component and they separated
168:20 into two bits. This actually looks nice. I mean I mean they're
168:25 teasing out some stuff in here but still got a lot of noise if
168:31 ask me. I think it's really . David. Yeah. Um Yeah
168:45 don't know. And I'm not I looked at this and this morning
168:48 was staring at it for a long . So this is a linear analysis
168:54 Murphy brewster and I don't know. just picking a bunch of regional field
169:02 direction. I don't know what that's for. Okay so the bell instrument
169:09 is the which is the three cara of inclined spinning disks. That's one
169:19 . The other instrument is is owned C. G. And it's called
169:24 falcon instrument. And it has a disk, a single big broad spinning
169:35 . And you might ask why one . Well this was developed by BHP
169:42 even though there's an hasn't an oil to it. It's basically a mining
169:49 and it always has been. So those targets they're all near surface.
169:57 death is not an issue. Everything near surface. I mean no one's
170:02 know one's mind go at the bottom the anatomical base and it's eight kilometers
170:08 . Right? I dig down through kilometers just to just to start
170:13 you know to strip mining or Right? So so miners everything is
170:19 the surface. They don't even think terms of death. Everything is if
170:22 listen to them talking about structures. just talking about surface features. They're
170:26 talking about anything with any vertical It's just the way they talk.
170:32 So for that reason they have they have a disc that's bigger. But
170:37 has four pairs of um of opposite accelerometers. So in fact because it
170:48 a it has a bigger disc. error is a little bit less just
170:56 of that geometry, but also it such redundancy in it because it's it's
171:02 as measurements. It's actually a better for measuring in the horizontal plane.
171:08 it doesn't do like, you it doesn't do like any, it
171:13 calculate directly anything with a Z component it. Obviously. Now this is
171:26 is the other, where was where there it is? Austin.
171:34 . Bridgeport's is, well, it's a new company anymore, I think
171:39 just called Bridgeport's now, Austin, dropped Austin but Bridgeport, They're trying
171:48 make a three access system. So kind of combined Everything. We're trying
171:58 have an instrument that has a big disc with eight accelerometers each Instead of
172:05 mine on a carousel. They've been to do that for a long
172:12 And by the way, when I they, when I say there's two
172:17 , they're all built by Lockheed they're all built by Lockheed, all
172:22 them. They build every instrument. build bells instrument. They build CGs
172:27 and they're working on Bridgeport's instrument. you know how in the world does
172:33 work? I have no idea because guys really hate each other. They
172:37 hate each other. Um Yeah, that's what that instrument is and they
172:47 . Okay so that's it. Now talk about this core NG test
172:51 There's a famous gravity and great geometry gravity test site in uh in western
173:00 . Just you know just east of . And uh basically data has been
173:11 has been donated and you can download . If you go into you know
173:16 car NG test site, it will you to a place where you can
173:20 a bunch of data, gravity and data and granularity data. So here's
173:24 the test site is. This is size of the of theirs to
173:29 So this is the ties of the data and I think this is the
173:33 , the site of the aero mag . Right? So this is the
173:38 data outline I think right uh and is the airborne gravity, the magenta
173:49 then the A. G. The grad geometry is the green. So
173:55 airborne air gravity grade geometry. All data has been donated. Here's the
174:02 gravity, There's the coastline. Perth right over here. That's that's the
174:07 test site. So here's the Here's the gravity data, the regional
174:14 gray to data with the airborne Their resume into the airborne gravity.
174:20 the airborne gravity and this is the geometry flowing at three different line spacing
174:28 oriented southwest northeast. So assuming and you can see this line spacings are
174:35 and then zooming in even more. is um topography and here is uh
174:45 and data integrated uh into um basically well it's it's it's the it's aero
175:02 in the korean death site integrated with guess land bouquet. So its gravity
175:10 the great it's the A. Converted to gravity. And then and
175:14 that stitched in with the airborne Bradley you can see that the resolution is
175:19 right in there. They have a mag and you can see all the
175:26 because this is outcropping basement. I all of these are little intrusions and
175:33 crust here is our key and it's very old crust. So here's some
175:40 noise application on the korean test So it's just this narrow strip in
175:47 middle and this is um standard And then so so that there's just
175:55 not CG anymore. It's Excalibur. just recently so CG just sold this
176:00 they call their their multi physics uh to a new company called Excalibur and
176:15 they have an ongoing battle with It's just two companies who can deny
176:21 the data the best. And so is just one of the many,
176:25 , many papers out there where they different Denoix zing techniques and here's a
176:33 a repeatability test over the car. using CGs noise testing difference. The
176:43 is uh I guess plus or minus at bars. So I think,
176:51 don't know why, I can't remember . I mean, I thought I
176:54 it, I thought I had Yeah. Right, That's it,
177:04 it. Um yeah, here's the from elbows to mill igel. It's
177:16 had to do milligram per meter, head boss equals one over 100 mg
177:26 meter. Okay, In other and that boss is essentially 10,000
177:36 10,000,000 of a middle gail. So very tiny. So This is like
177:44 , 7 over 10,000 mg. So really tiny and they're very, you
177:51 , very tiny units. So they're sensitive obviously. Okay, so the
177:57 and version of occurring test data by School away. So let's say they've
178:02 okay. So they did uh they the car in test data and um
178:10 see joint inversion. So that means they're in this term, the
178:16 the phrase joint inversion can mean a of different things to a lot of
178:22 people remember I told you inversion means lot of them things talk in this
178:30 with great amateur. What they mean they're inverting all the components, they
178:35 considering all the components when they're doing inversion, that's what they mean.
178:43 , so this table. I think is from a paper in A.
178:46 . L. E. It looks a T. L. E.
178:49 of table. And let's say this all for the CGs instrument again,
179:00 difference, repeat surveying commons, estimated amplitude, estimated. Yeah, it's
179:09 it's just more more on the battle noise between the two contractors. Um
179:22 A and Peterson presented adverse method to strike and depth of thin sheet
179:29 So I was reading this, let get to this point. This is
179:33 41. So, so these are dykes and contacts. There are models
179:47 strike in the in the Y. . So from south to north this
179:53 and projection of the dip angle into line. Yeah, I'm not sure
179:59 this what this is about. We're gonna worry about it. So here's
180:08 uh F. T. G. or is it F. T.
180:12 . Or is it? Um who's the authors, robert said
180:17 Uh No, this is a Falcon , but they flew it over the
180:27 part of Lake Tanganyika. So here's East African Rift one. This is
180:30 eastern branch and this area here, is their peak, their their permit
180:39 energy permit area right down here. it's kind of hatch erred in in
180:44 figure here. So just on half the half of the lake and this
180:48 topography. Yeah. So let's see just looks like. So there's a
180:55 seismic line shot right here. So is this is this is the lake
181:01 here. This is their half of of uh Tanzania. And here's the
181:07 . So you can see there's some drop blocks here and uh there's some
181:13 centers in there. So they're they're that from these data and then they
181:20 this structural interpretation where this this blocks ? To see uh They have little
181:28 structures that they've mapping in here. that saying saying? My notes.
181:35 have highlighted two major depot centers were in the magnetic, in the magnetic
181:41 thickness is in excess of weight, the magnetic depth of basement in north
181:48 west central parts of the survey area sediment thicknesses in excess of four and
181:53 kilometers. So let's just look at . I see it's getting deeper.
182:01 yeah, so this is their magnetic . So these are the deep half
182:09 right here in the center as That's it. Did you learn something
182:27 that? Did any of that make to you? It's a lot but
182:33 makes sense. I just have to through it again. Yeah. So
182:38 , I think it's important to just that gradients, you know, they're
182:42 the derivative of the field except in case is they're actually measured gradients.
182:47 ? So I think that's the key understand that's why I made the point
182:51 the beginning about measured magnetic gradients you know, in this case it's
182:57 the same. It's two accelerometers that separated but it's all encased in one
183:04 and these surveys are really, really . I mean only the big oil
183:11 can afford to pay for these Um yeah. And then they go
183:16 like I said listen this is this 1988 and this picture looks like it
183:20 taken out of you know, should things should be sitting on a model
183:24 or something. But yeah, this the 90s they started sailing around collecting
183:32 data in the gulf of Mexico and did it and then they did some
183:37 they were driving around with the instruments vans and then they only started flying
183:42 them Jeez around 2000. I mean want to say it was.
183:52 Yeah. Yeah. Because I was business I want to say it's only
183:58 15 years, 10 to 15 years they've been collecting gradient data reliably reliably
184:06 airborne platforms. So it's rarely really stuff. I think I think this
184:12 a really good figure because it explains , you know, the relationship between
184:18 and why is it? So that's way, remember that's one way you
184:22 interpret these the way it's not used many people but I think it's an
184:26 one. And then of course the way is inversion inversion is the most
184:32 used way to interpret these data. remember inversion you start with a model
184:38 the closer you are to the the better the inversion works okay.
184:44 then um there's the bell instrument and of course the CG instrument coming
184:51 Don't worry about all, they're all about the noise. That's, that's
184:54 thing, the instrument companies, I the acquisition companies and then a lot
185:00 these examples are about that um in , so this direct mapping inversions and
185:08 variant calculation because they are irritation. right. Some are completely irritation in
185:14 direction and some are just irritation of horizontal I believe. And then just
185:21 of some, I like this one best, this is just a
185:24 I mean slope, everything else you know, really kind of hard
185:29 understand. There's the falcon instrument. it's a big giant just in Bridgeforth
185:36 trying to make a hybrid of both those and there's the famous korean test
185:41 where I think Bell has done some , conscious and test data there as
185:48 . And yeah, more inversion stuff then more, yeah, more techniques
185:57 map these things. I'm not sure are map from but yeah,
186:09 So I also noted in my I still got, I got the
186:14 wrong, I said, I said the 14th but Wednesday is the 50
186:20 , but Wednesday is the exam Yes, I believe so yes,
186:28 do the same thing on Tuesday, send it up, I'll send it
186:31 then and then you just give it me whatever thursday morning. Okay.
186:37 that that should be fine and then , I'll just score it and then
186:43 guess I got to get into, can get into the thing, the
186:46 center in my US thing and I go ahead and give you a
186:52 So you're doing fine. No, worry about anything, so thank
187:04 Alright then. So um that's It's uh I've had it, I've
187:11 enough. Um yeah, just send any notes. You have any questions
187:18 this? So this is gonna be this this test is gonna be 567
187:25 eight. Right? Yes, I whatever. 6, 6, 7
187:30 eight. There's just three, there's It's just three elections because apparatus ah
187:46 sorry 5678. So it's gonna be super continents and basic classification rules of
187:57 . And then and then um the , Wilson cycle and coastal sites and
188:05 maybe a question or two about gradients heat flow but nothing nothing too heavy
188:10 this stuff. It's new material and understand that. My notes, my
188:16 be a little bit better so. , alright, well I'll send you
188:23 thing on Tuesday. Okay, thank so much.
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