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GEOL7330 Potential Field Methods - Day1 01-20-2023
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00:13 Yes, got it. Are we now? Okay, great. So
00:25 already chatting about what you're doing, you're from and everything. Um Now
00:33 the notes here. Did you did download the notes? I have to
00:43 Yeah. Yeah. Yeah, no getting into my GPS. Alright,
00:50 , so um seven lectures to exams exercise and I already explained to you
00:57 we may. I got a plan for this. It will be another
01:02 . Um Probably test but more It's about porn. It's about I'm
01:19 . Hello? Yes, I'm I'm right now. I'm I need to
01:28 you first thing monday morning, have insurance and I'll send that information first
01:32 monday morning. I know you don't it well then I'm gonna have to
01:41 because I mean, I'm not gonna home till like six o'clock.
01:46 So. Alright, so Right, seven or eight lectures, I'm hoping
01:50 get this thing worked out. I'm hard on it. I got a
01:53 of different two pronged attack. That's the problem because that's that's a good
01:57 to do. Um kind of like basic theory, data interpretation,
02:05 uh processing, you know, interpretation and then then 5 67. I
02:13 uh the good part because I'm teaching to interpret gravity and that's what my
02:19 is. I'm writing a book about and basically the idea is we're gonna
02:25 through different kinds of base where we're learn all kinds of bases, There
02:29 classifications and then we're gonna go to different kind of basic platform basis rift
02:35 , You know, four land bases our basis, passive margin basis and
02:41 bases that are kind of complicated and gonna lots of examples that show you
02:47 kind of anomalies are produced in those , whether from mythologies, structures,
02:52 like that. So that's the The thesis of um the grading is
03:00 for each exam And then 20% for exercise. So if we do switch
03:05 , I'll probably give you a paper read. And then you can summarize
03:09 of like connect what you learned here what's in the paper like Oh,
03:13 see that they that way. So can I can I can learn what
03:19 learn. All right, So, so here's the beginning and I had
03:25 get my notes out for this But yeah, so gravity magnetic methods
03:33 how come can I get rid of thing? Man? That's, that
03:43 bites, you know, put it there for right now. Okay.
03:50 so the history of pragmatic method. they go all the way back to
03:55 of load stones by uh the Greek fails, fails of militants. And
04:04 the Chinese also discovered both stone and fact jumping like 1200 years or so
04:11 years, 1200 years. They actually the root of military compass. Always
04:19 back to you know then And then the matter? You can't get rid
04:25 that thing. Okay, thank Alright. Um Right, so then
04:37 , the italian scientist Galileo. Uh dropped, he got the famous experiment
04:42 he dropped two different size mass, two masses off our pizza to demonstrate
04:50 they hit the ground at the same . Okay. Um and of course
04:55 Gilbert, do you know about? don't know. Okay, so he
05:00 was, he wrote a famous book called day magnet day magnetic magnet.
05:07 magnet and of course he famously proclaimed world as a magnet. So he
05:13 the north polar magnetic field back in . Start doing Oh I think so
05:31 Okay, so um the first folks use potential fields to prospect were the
05:39 and they in 1630 they used magnets data magnetism to prospect for iron ore
05:46 then uh jean, is that how say that 16 72? He's a
05:52 astronomer on and see, he mentioned , He mentioned that depends only at
06:02 at the near the equator of french well as in paris. And so
06:07 he worked out that the earth shape a little bit different because of
06:10 Okay. And of course the place very famous for laplace equation which we
06:17 know from geophysics and then um but developing the spherical harmonic polynomial. And
06:31 then uh with regard to isil the idea that the crust of the
06:35 was floating in the man kind of an ice cube floating in a glass
06:39 water. There were two ideas that being argued between john pratt and George
06:47 Carey. And um and that was course they were called the hypotheses.
07:00 Pratt argued that the cross is uniformly and just had a different density variation
07:05 area said no across various thickness and of hit the thicker crust roots into
07:13 mantle and they're both kind of right . Um Then James Clerk Maxwell,
07:21 Maxwell equations, you probably know that class, uh you know the four
07:26 that connect electro Magnetics describe electromagnetic And then the first actual airborne magnetic
07:33 measurements were made from a balloon by Thompson elder in 1910. So we're
07:39 up to the 20th century, I know how I'm bending, mens mens
07:49 mens mens mens should not say So he's a duck's geophysicist and geologist
07:58 he's attributed with developing instrumentation to measure , particularly at sea. And then
08:08 guy Google from 1932. This is very interesting one. So he was
08:14 Hungarian and he he was, he the first gas reservoirs in Transylvania
08:24 So it was the first use gravity explore for hydrocarbons and victor. He
08:30 a very famous person, he has long history of long resident worked at
08:36 . He's, he's born in Russia Ginsburg, but he worked at golf
08:41 during the World War two where he the that they used to find Germans
08:46 range. So he's uh yeah um then you know Sgs actually conducted the
08:56 parable air man servant. And that Hannah 1994 from the first airport 1940
09:04 10,009 miles over the north slope of . Okay so we'll look at satellite
09:13 we started deploying satellites to measure gravity data. Uh 97 9 with the
09:18 sat Nasa launched that. And so just measuring the Earth's magnetic field from
09:25 very high altitude elevation. And then Germans launched the champ 2000 and that
09:32 at about 455 kilometers um of the . And then Nasa and Germany launched
09:40 . And this one is still collecting . There's there's talks on every year
09:45 the age where and they do a of leader not a lot of
09:49 things like environmental relations. And then the E. S. A.
09:55 Space agency launched gold which is a is a great atmosphere. And those
10:02 of what you really want to read history of gravity Magnetics. You can
10:05 out S. E. G. . 75th anniversary articles um with division
10:13 you know I have those if you to. But those uh yeah so
10:18 kind of an introduction into the history gravity Magnetics. Um And any questions
10:28 that observation. Alright so. Alright let's start with potential. Right,
10:39 we're gonna go potential then force and we'll start looking at rock properties.
10:47 . Oh I think everyone really, think it's important to, I mean
10:57 don't think it's I don't think it's necessary to have to be able to
11:03 or write these formulas down from I mean this one, I think
11:08 probably knows that anyways due to this , but it is important to understand
11:13 the potential is they want to force . And so I think those are
11:19 because once you understand those ideas then can start thinking about kind of rocks
11:26 stuff that produce anomalies. So gravitational is just using uh this is the
11:34 constant and it's equal to this right . It changes over time. Um
11:41 the reactions of constant times mass over distance. And so it's actually
11:47 It's the work required to move something a distance, to move a massive
11:52 of the mass over a distance. the Joy is a quick potential surface
12:00 we measure that in meters economy measured meters of ups. Uh But for
12:13 it is sea level. Um Okay , gravitational forest, which is And
12:22 the unit it's uh quality is uh kind of mass per area,
12:31 For probably two masses over area square through that. So you probably remember
12:40 m per second from physics or 32 per second. But that's also 980
12:45 or 980,000 Milligan and Milligan is the that you always see gravity expressed in
12:53 industry, gravity is always in the . And most data are collected.
13:00 resolution of gravity data is one Typically they're measuring contractors will tell you
13:11 we can measure you know practice of that's fine, you know, But
13:16 one and that is like one part million. So let's grab it.
13:21 be measured with very extreme actors. , so when any potential work of
13:27 is more complicated because the gravity field mono polar. Everything points down the
13:31 field. Di polar. So you you know the poor situation. So
13:35 have two parts of the magnetic field B and H. To make field
13:43 and the the potential B times this uh times delta scale of potential.
13:59 . Right. This is the magnetic potential over there. Um Okay.
14:08 the forest is equal to the sum the two components that Hb H.
14:14 and M. A writer. H . Is the field strength vector.
14:18 M. Is the magnetization like and some of those times the probability is
14:24 to the magnetic funeral. And but this part is important parts in boxes
14:32 we talk about 45 Tesla's might hear say gamma same thing. Um This
14:43 Tesla's or 0.45 Gauss. No one to everyone everyone use when we talk
14:51 . And again the resolution one. that's about 20 clocks in terms of
14:58 . Okay. The field actually ranges over 60,000 to less than £30 At
15:05 Poles. It's like over 60,000. can imagine those flux lines all
15:10 So it's more. And the magnetic is the weakest like 30,000. Just
15:16 you can imagine spreading out. That's it works. So that makes
15:22 It's not computing. Great. So financial is always described as in
15:31 of work, the amount of work to move some particle from one position
15:37 the next position through a field. the idea. So potential is always
15:43 . You know? And If you to, I don't know if you
15:47 about Rick. You want to read this stuff. I think somebody's at
15:52 library but 95. My friend in fact I have some slices and
15:58 wrote a book called theory and dramatic . And so in any case uh
16:09 a pretty good guy. Alright so I mentioned the GOP before the
16:16 I. As I said, it's equal potential service. So what you're
16:20 at here is the relative sea the height of the sea, relative
16:26 the W. G. S Spirit. You know what steroids and
16:30 are. Okay. Yeah. So to WTS. Which is a a
16:39 surface it is a it is derived polynomial has zonal sectoral, all this
16:47 components in and its attempt to best the shape of the so the is
16:55 and it is relative to the it's above it over here. So
17:02 what this means. Is there's some masses out here that's producing that that
17:07 masses here. There's a big mass here that's that's producing these big
17:13 So that's what that means. So is a is a measured surface in
17:19 . So that's important to think Okay, this is a really busy
17:26 . This is from book 2013 and is comparing topography which is this jiggly
17:34 up here, right with the Oid which is this long dash flying
17:41 . Right. So uh so the level, the sea levels down here
17:47 the ellipse oid, which is this uh Why here let's see. And
17:58 all these are just right angles, angles to the to the or oid
18:06 . And this goes to the center the earth dot. So gravity preventers
18:13 the vertical gravity relative to the so other words it's gonna be deflected from
18:21 actual uh angle through the earth. ? So that deflection when people do
18:32 said you measured. Right. So can we can do the oceans with
18:38 data because we have satellites out there measure that when places they measure the
18:45 , they just stack that data out we can measure the marine areas.
18:52 land, land is like it doesn't like why? So we can't measure
18:58 with satellites. These we have to to go in with a meter that
19:03 the gravity but also measures this So there there are joyed measurements which
19:11 gravity measures. They're also have the angle measures. So there are far
19:17 adults. It's free dating download from National Geodetic Survey. The NGS they
19:26 . Okay, so right, normal is defined preferentially avoids here. So
19:32 gravity is to the spirit it looks here. So that's that's the
19:37 Um Yeah. Okay. Alright. that's that's that kind of explains the
19:44 of those those things. Okay, now here's my little case history.
19:50 is um this is Chavez and and they did was these are g Oid
19:59 anomalies over Yellowstone. Right? So the topography. So you know,
20:05 or minus 4,404,000 m on this color . So everything here of course is
20:11 starts over here. Um use the it goes from 2 to 20
20:18 So it's comparatively tiny. It's a small difference. Only 2020 m 20
20:25 is like you know nothing in So even though these colors are
20:31 This is just a tiny tiny novel terms of amplifying and then this is
20:36 crust the crust here. This is the service tomorrow. This is going
20:42 on this 30 year 55. So on the order of I would say
20:48 20 to maybe 60 km that's pretty . And then they did they had
20:55 they tested to s way demographic So this is this is kind of
21:03 I'm gonna do things. I'm gonna you, I'm gonna explain something,
21:06 gonna show some application and all I have all these papers you want
21:11 else? Um So they have this , N. W. U.
21:17 . One one dash S very catchy . And so this is s way
21:23 at depth 50 kilometers, 100 Uh just basically looking at depth slices
21:30 the crust. And this is the always in percent, you probably have
21:36 any commodity bakers before. So when do the pictures they make like this
21:42 always used some percentages of and and do the color scale backwards from what
21:55 do, gravity Magnetics. We always always color magnetic maximum read and minimum
22:02 . But they decided that guys always it the other way around. They
22:07 philosophies, they always blue and slow they call it red. And I
22:11 they do it that way because it right, slow slow and be you
22:17 hot hot would make things slower. ? So that's why they do it
22:21 in any case you can see this this is the the trace of the
22:28 track. But the north America's very you see it going all the way
22:34 . So the inversion of all results both tests indicate that madam densities derived
22:40 can be integrated with tomography to include improve the mantle imaging. And that
22:47 a necessary thing. Mantle imaging It's really important. I mean,
22:54 anomalies are like, okay, so are you looking at? So that's
22:58 degrees right? The resolution of toma to market, I think it's like
23:02 degree like 100 clock in and then It's like 50 club plus mine.
23:13 , so yeah, in any so that's a good thing to
23:16 All right. So, we can for fun, we can look at
23:21 potential uh graduate potential of MArs which , which is of course fun.
23:27 let me see what I have some here. So, right, the
23:32 Southern highlands, this this area here from goth topography. So this this
23:42 topography. MS kurt This is the that they manager from. Okay,
23:51 an airy conversation model. And so predict that a large portion of the
23:55 should be composed of ancient enriched representative sample of primordial crust. And
24:03 think I got my notes pretty Um Right. Published estimates of Meyers
24:12 crustal things have ranged from 1 to clones. And uh in any
24:20 So, So they're saying that this power, this high power, this
24:26 uh root power route of the power this this is harmonic degree 0-30 and
24:33 that this high power um with low degrees is most likely a result of
24:41 load and global flexion associate with this order site. And then this five
24:50 um whenever I go to the, you been to the EU? You
24:55 really go this next year is gonna , this year is gonna be
24:59 It's the best common states. I it's amazing. You should go,
25:05 you can submit a paper, you submit a poster. In any
25:11 It's uh there'll be 20,000 research students and the Eu covers all covers
25:22 oceans, magnetosphere planetary like seeking those those guys don't know anything and they
25:30 big fights and I got no dog the fight. So I like the
25:35 just wanted the one in Chicago. always in December going to the one
25:38 Chicago last month for the first time 2019 there were 17,000 which is pretty
25:47 considering Chicago. So you should think money. It's about if there's 11
25:54 I would choose that would be the I would for you have a new
26:01 everyday work anyways. Right? So , I like I like the planetary
26:05 because I don't have a dog. , now it's like a magnetic
26:12 Okay. Um so just remember the hat that I talked about before,
26:16 some data from it and this is . So it's very, very tiny
26:25 very very small enough. And the that kind of sticks up at least
26:33 me is that this just looks like data are, I mean it looks
26:38 it's just one dominant waving percolating through . Um, In any case.
26:46 this, the Mag said that's a km altitude and then they convert that
26:53 potential. How do you convert the potentially integrate? So the, the
27:00 when you take the driven potential, get the field and interval, the
27:04 brings it back to potential. so here's the potential and I guess
27:09 is in New Tesla per me Plus or -2.7. So that again
27:18 small and it looks, it looks like this. But uh, it
27:24 like, you know, things are of subdued a little bit like things
27:29 short and a little bit. I wavelengths are kind of like uh
27:35 Alright. And then what they did they downward continued that continuation. We're
27:41 talk about that more Probably tomorrow. think what continuation is is the financial
27:48 he says if you know the field one elevation and you know it every
27:54 . As long as there are no or since between those two elevations.
27:59 , so I think I would continue to 10 km. So it went
28:03 3 410. So that will But as long as they're still above
28:11 you're probably not going to many So it's probably okay. And again
28:16 can see that now always going are up. They're getting smaller and smaller
28:21 you're getting closer to the source you . So you go from these just
28:26 attention to this area. Here you from those to these and you can
28:32 that the amount is getting smaller smaller you're getting closer to the source.
28:36 that's how it's worked. And then this they did a they did an
28:42 . We're gonna talk about that as . But basically there's two kinds of
28:48 forward modeling. When you take a and you calculate what its responses and
28:53 in responding where you take data and try to figure out what the models
28:59 can invert for rock properties in this magnetic susceptibility. So actually invert this
29:06 is the distribution of the magnetization of rocks. These are s I can't
29:13 that conversion easily. Um Yeah in case my sense is these are not
29:22 but But that if you look at bottom one and and if I can
29:31 at all these bats they're all just alike, aren't they? Um Yeah
29:38 that's an example of potential of magnetic and then of course you got to
29:43 back to mars and then here's a by journey and Stefanik. Um See
29:49 is security. Alright, so let's there the satellite that measures 400 meet
30:02 altitude. And what they did was took 14 die poles. Okay.
30:07 here's the field And then here's the of potential. So this is an
30:12 to get here. And they represented by these 14 disciples trying to model
30:18 field and they're suggesting that this exercise they're interpreting that different stages of
30:30 Yeah. Results suggest states and organizations episodes of the mechanism. So I
30:41 in my notes here that maybe you to take a little break point.
30:45 got a late start. I don't which one keep going. Alright,
30:50 . Good. It's easy with one . There's no disagree. Okay,
31:01 here's I'm sorry. Here's my summary potential. This is after this
31:05 But anyways so remember grabbing our units exploration, millions tests and you might
31:15 old people like me say gammas. exactly the same. Now again,
31:27 is always about work. Okay. the greater potential our field for
31:34 And of course the integral goes back I said and again, once
31:39 five times joy is a measured act potential subjects typically immediately. All
31:47 so that we can graduate from from to force fields. And so there
31:55 the gravity may I feel they are to the fields they are conservative,
32:01 means that they have continuous to emit , they're harmonic because they satisfy the
32:06 equations. In other words, the order differential equation with respect to position
32:10 equal to zero. Del square times field del square is zero. They
32:21 the rotational. In other words, no funny business going on in the
32:26 . They don't like do funny no vorticity. And they're so in
32:33 ? And then that flex through the of zero. So what you got
32:36 going in is the same as what got going out. Um They can
32:41 and contract, but but the field concerned. Okay, so it's a
32:46 confusing to me. And then of they are, they are flux.
32:51 fields, you know, the properties right there measured their measured over now
33:00 . Uh for points and regions that outside appear, they just follow the
33:08 white voice lines reduces, but for inside 245 mrs constant times. I'm
33:22 gonna test your first uh This is F. Y. Okay, so
33:28 law, that's actually Newton's universal law gravitation attraction. And that says the
33:34 between two masses is equal to their or their distance apart times gravitational
33:40 And that's that's something everybody knows. But I mean this is a theoretical
33:48 because the masses are point masses. a non physical. And the distance
33:53 fisherman's. That's also so this constant over time because our ability to measure
34:02 better. So you know Newton's universal of gravitation was thought to be true
34:10 universal to this guy named Albert Einstein demonstrated that this is gravity actually spends
34:18 . So just just to show that still a theory. Still theoretical.
34:25 so this guy got um Friedrich Gauss think um Glosses law basically is is
34:35 this idea that you get this from theory as well that you have this
34:40 can encapsulate some disturbance, some little and a sphere. And you can
34:46 over that sphere. Remember we're talking grades there, right? The same
34:50 of idea. So total massive push the normal component of the graduate
34:54 integrate over a closed mind in the . Yeah so it's a surface integral
34:59 gravitational flux. And uh inside you to use you have to use poison
35:06 that's why I mentioned question so um here's a little example of gravity.
35:17 applying God's law for gravity and it's be, he's using Michael gravity basically
35:25 high resolution measured data over small And um my program is modeled for
35:35 a lot to examine carboniferous limestone, , lime stones and this is in
35:43 catchment area. This public water in southern U. K. Right on
35:48 on the coast. And then we down to Bahamas and they did the
35:53 thing. I mean study by the reefs. And this was for a
35:57 terminal of pork terminal construction to sort make sure there's no voids. You
36:03 what car stitches, right cartridges. like for its like limestone, but
36:09 water will reach out cavities in them then become hazards and big sinkholes ahead
36:13 there or something that's called constituting. yeah. Um, okay, so
36:24 the UK example right here is great and along the coast down here.
36:30 interesting here and along that coast, little tiny here down here, this
36:34 tiny area right here and that area right here. So it's a
36:40 tiny, tiny, uh, but it's okay, it's still gonna
36:43 fun. So look, it goes 70 80 69. So that's 100
36:49 . So it's like 100 and 20 . It goes from 88 42,
36:58 , 80. So it's 120 it a tiny tiny area. And the
37:02 dots are all the little stations and is Milan that goes from 0.6 minus
37:11 plus 0.38. Okay, so and that adds up to, that
37:18 up to 0.1. So it adds to the whole range is 1/10 of
37:26 . You can do services, but you have to do a lot
37:29 special operations. But this data once you get this, it's actually
37:32 beautiful data and you can see the right here. So these are gonna
37:38 , but you might target those are deficiencies. So that's gonna be where
37:42 might think that there is uh you , a karst feature in it.
37:49 , okay. Um and here's the a little three D rendering of their
37:55 where got to these things. So they're doing is I think they're assuming
38:00 constant density of the invert infrastructure. they have the density counts and then
38:06 that then they have adapted to define these features and that's kind of busy
38:11 I think there's another figure that Oh no, that doesn't.
38:15 so anyways, right, so they hatch into the deepest ones down
38:22 and then they have big areas patch 55, 5 m, five
38:35 Yeah, my own cabinet things in . So what did they say?
38:39 me just okay, This result providing depth incident between two and 5 meters
38:52 our south training features. So best these, I think. Yeah.
38:59 using, Alright, so all right let's jump down to the Bahamas.
39:06 this grand bahama island and it's kind like beneath this thing and this is
39:10 container factory this down here and the ports and they wanna, I guess
39:16 want to out build it's taking here they want to make sure they can
39:20 which is microgravity. Now this let's get some scaling this 79
39:26 78 degrees west. That is on word of 100 kilometers, 111 kilometers
39:32 degree. It's always it's always a , so whenever you see in that
39:40 no scale, it's just some Okay so oops. Ah alright so
39:51 this now, this is a little bigger. So this goes from zero
39:53 about 3 50 So it's about 350 350 m. So it's a lot
40:02 . The other ones just like and goes from, okay, they call
40:09 just it's still the lows are still flip they flip the switch, it
40:15 from minus point oh six plus So again the dynamic range is about
40:20 say like point 1/10 of a. And then you see you have this
40:25 eyes in what they called, not one, not only to this cross
40:30 A to B. And then going de sc going, I always I
40:35 know what they're doing it this But anyways C. D.
40:38 Um they intersect this one and this goes here so you can see what
40:43 those results look like. And here have it. So the 20
40:52 And and and and even hopefully we the exercise. Well the observed it
40:58 always dots. Those represent the actual measures and calculated from modern. Always
41:07 solid one. It's calculated from So here's the result, here's their
41:15 data in the dots versus the calculate is A to B. So here
41:20 have some shallow features and then you this steep feature here. This big
41:25 down here at 10 m depth, m step and see the deep.
41:32 this is actually going south the door they intersect here an anomaly one.
41:37 these these models should tie there uh integrated. All right. Um Is
41:45 anything else I think to himself interesting or was that was? And then
41:53 feature here. This is just they what's called oil or depth estimation and
41:58 going to learn about that. Um , alright. For Magnetics. So
42:08 it is of course more comfort. this this is the formula for so
42:14 uh our regional integral of del field normal to the field. So that's
42:28 a like a. O. Is do a here's what happened and what
42:37 find one of them wasn't good enough up. It's not asking me it's
42:49 now. Yes, I stopped. stopped. Right. Yeah,
42:54 Yeah. Um Okay. Right. yeah, so it's it's very simple
43:02 to like we were talking about in beginning before class. You know,
43:06 this is all, can you pull the it's the same sort of
43:11 Okay, the magnetosphere. So the magnetic field interacts with solar winds to
43:22 the magnetosphere. So the Earth is slow circle down here is here down
43:28 . But then you have, you the plasma sphere, this geometry of
43:31 solar winds are blowing this way. the main atmosphere is important. It's
43:37 so you understand how have you seen figures like this before? Yeah,
43:45 simple ones. But this one is really nice one. And because it
43:50 the different components plasma sphere, the ring currents, plasma sheet, magnetic
43:55 , plasma, mantle tail, current then what they call the inter
44:00 And then the magneto pause. you know, lots of stuff to
44:06 about. But in any case just get your sense of what the magnetic
44:10 magnetosphere around the Earth looks like. then um I'm sure you've heard of
44:15 Northern lights, right? Aurora So that's where you've seen.
44:23 So yeah, so that's basically um when the solar winds interact with the
44:31 at the polls, because the you know, the the fuel lines
44:35 converging, getting vertical uh electrons are in the other atmosphere when they lose
44:43 energy debate in the So yeah, are that's just and uh whatever.
44:51 and the fact of the magnetosphere. , so getting back to the Earth
44:56 a giant magnet under as well, would say the geographic north pole,
45:05 ? Is that where the magnetic north the magnetic north pole is, you
45:10 sort of at a different angle that is called declination. And then of
45:16 the field comes out of one pole rapture and goes to the other
45:21 So what that means is that the earth cornfield? What I'm talking about
45:27 , it is inclined at different angles on where you are at on the
45:33 . So this is called declination at magnetic equator field is you know,
45:40 uh flat as we say, say flat, zero inclination is horizontal.
45:47 then of course at the poles that magnetic pole, rather the field is
45:51 . Okay. And as I it's it's well over 60,000. Less
45:56 30,000 when you go from pool. , so here's a contour map of
46:04 magnetic field intensity. Right? So is 20, you can see this
46:08 25,000 going up. These are 5000 . So that's 30 35 40 45
46:18 55,000. And this goes up here to I think that's 85,000. There's
46:25 southern pole. The maps only go or minus 70 degrees the north
46:32 So sweet. Is that it? guess that's it. That's the north
46:36 , is it? And we have . Yeah disclosure there now I think
46:41 pulls them somewhere else. Yeah. . Alright. So we can look
46:47 the inclination. So this is the core here, this yellow line and
46:54 goes up to let's see these these by 20. So there's 2040 60
47:01 . Yeah, it doesn't go it doesn't go up to 80.
47:08 these are by Tuesday, is that ? Yeah. 2 to 4.
47:15 86 degrees inclination. But this is magnetic sample. That's 80. That's
47:23 the 2468. Yeah. So that's the inclination. You can see that
47:31 magnetic. So here's the here's the equator. So they're roughly satisfied.
47:38 not really. This is well. . And that's fine. Let's look
47:45 duck. So this means this is angle. So this is so this
47:51 is my and this is zero degrees . Those lines all run straight into
47:58 pole. Right? Here is the pole. So all these declarations like
48:03 here is gonna you know. And I think yeah reds are positive
48:08 lose their negative. So bed for methods we have to adjust the
48:17 All right. Right. Right. . Exactly. Right. Yeah.
48:25 Okay. Let's just dig into because some important concepts to understand it.
48:31 then so at either pole, north soft pole the magnetic field produced.
48:37 mean, it's only if the magnetization only from the inducing field and the
48:45 will produce the symmetric hot. No what annual you transact through the
48:52 Doesn't matter. It will produce a economy. The same source body.
48:59 mean it will be magnetized this way at the magnetic equated depends on what
49:07 . So from south to north it produce this magnetic mode. Right?
49:14 then so yeah, the inducing field write the same thing. So you
49:21 this risk is horizontal. Right? . So that means in between the
49:30 and polls in the northern atmosphere you a what we call an anomaly taker
49:40 the source will be so this is So this will be right in that
49:45 halfway between the low. So in northern hemisphere the high of the
49:51 there is always south of the source is a direction and in the southern
49:59 high is north of the certified. . So what does that look like
50:07 three dimensions. So here we have same source, the square Q.
50:14 and north pole. It produces a heil just like can you see that
50:20 these kind of tours? See that at the magnetic equator it produces,
50:28 is why this. Now you're getting sense for a while I say south
50:31 north south to north. And and it's always sort of but the same
50:37 for produced this symmetric lo So now you go from here just down to
50:49 inclination, you can see that this starts to migrate southward. You start
50:54 develop low at the northern part of . You go down another 30° and
51:00 highest migrated down here. Now the was here. And then you go
51:04 a pretty good deal up to See how that how that works.
51:08 know from here to here to here here actually I said little is abc
51:17 but you would go as you you know as your as your source
51:23 softly in the northern hemisphere. What the south pole? So.
51:29 Two things at the same time saying pole equator obviously the equator. But
51:34 see that's the same monopoly and all all I did from because it's so
51:41 you're at the south pole again it's poll. So there's the same the
51:46 . But then as you move north latitude 60°. You see that this this
51:52 now the high sense to moderate uh the North. Right? And as
51:58 you and as you go closer to equator of the high line further and
52:04 finally the highest place quite well as . So it's the same thing
52:11 But that's that help you visualize how last night again we talked at
52:18 S. H. Meeting and there a profile, a magnetic profile and
52:25 was a model and I said it to me like it's hemisphere. Absolutely
52:35 . And I knew that because the between the profile of. Okay,
52:46 this is this is a historical reference God. So gas. Um.
52:56 . Yeah. Yeah. So uh earliest recorded magnetic intensity is useful for
53:01 present politics stuff. This is from this is 9 18 44. This
53:08 an old paper, the first the um Measurements of 1790s. Okay.
53:18 God's developed method in 1832. So Lewis is doing, he said I
53:24 to test it. So he's gonna to these cities around the world and
53:28 the magnetic field and compare this. go go's presented his law. His
53:34 in 1831. Loomis tested it Um direct measurements in 1844. Just pay
53:43 we now for the few elements Okay so what I'm calling dr nation
53:49 called variant when I call inclination they what I call field trip. They
53:54 intense. So there's some terminology. What is not to say the appearance
54:01 a general theory of terrestrial magnetism from name. So celebrated back in the
54:07 uh furnishing the three elements inspiration. have computed from the three elements of
54:16 Station, the four tablespoons. So just show you one. So here's
54:19 of the tables from that paper. again, so here's declamation, inclination
54:27 field strength. And you have different Montreal Syracuse, Albany, Albany spring
54:35 Hartford whatever most of them. The here's here's Loomis I think from yeah
54:47 measurement is from uh cause presented oh he presented a law. So he's
54:57 his idea. And so this is difference in a degree. So to
55:04 . Anyways. So that's that's some scientific historical stuff. And This is
55:13 Loomis conclusion he says from the sealed way they talked to deal with uh
55:19 is not manifested in respect to magnetic . We may expect that in a
55:23 years the errors of God's theory for part of global. Pretty well known
55:28 it is to be hoped to The illustrious author, resume the discussion
55:34 give this theory the greatest. So is a very famous man is big
55:37 of in Brunswick Germany. And then an 18th session compass. Just for
55:44 . I just stopped at it. Okay so the summary of of magnetic
55:52 fields, gravity. The r vector , they obey the classes uh equation
55:58 poisons equations. Um Law are the for calculating potential fields and the Earth's
56:06 field. So the same source will a different not only shape depending on
56:13 it is on the earth and So that's really because of the
56:18 declination feels straight. Okay, so you wanna take a little break
56:24 Good. Good, good. So 17. Am I going too
56:38 All right. I mean I just I mean so that's the theoretical stuff
56:44 I'd like to just now we're gonna about density and magnetization. Okay,
56:49 we start with that easiest for um both density is controlled and controlled by
56:57 minister of the grain density porosity and course space fluid. And you can
57:01 this by weighing a sample and air adversity of water. And the difference
57:07 gonna be what it's um it's measured by relating ferocity to the matrix
57:15 Robi That's that's gambling. But there also roby measurements like um it's estimated
57:23 by assuming that increases like passion will you some examples of that. Um
57:29 the units we use graphic here gcc often literature, you might see kilogram
57:39 usually industry, everybody talks. So rocks in generally range from 1.92
57:52 basically Crystal and Ross in the The upper crust brand. Um
58:01 in general. These are just rules thumb. Lower across 2.9-3. And
58:08 the upper mantle uh will be right , 3.2, maybe a little bit
58:17 if it's like close to a spreading . Okay, so We're gonna track
58:26 of three rock types Sansom granite and various sources, there's just, you
58:36 , there's just tons of literature out that have these tabulated uh rock samples
58:44 their destinies and their mechanization center. ? So here's a fraction of all
58:51 from Carmichael. Carmichael is, you , CRC manuals goes up. CRC
58:58 all kinds of mathematical table. They rockets, right? So Carmichael.
59:04 is mathematical CRC handbook rock properties. , So here's Here's the comparison of
59:13 bulk densities actually frequencies. So a of granite. Right? The density
59:21 sandstone density. This is dash It's pretty variable assaults. They're more
59:28 , but they can be sent down . So, but these are the
59:32 things. So sand stones are typically the range range here density some
59:37 It's in here. And what's also ? Just as a sort of
59:43 Okay, we can look specifically at . This is from Carmichael again.
59:47 . So the main density from their 2.2 Plus 9.2 Standard Deviation. And
59:57 is a history graham showing that the of densities pretty well behaved Granted.
60:05 mean, that is 2.66 And That's very well. So, I
60:13 , I've always used like 2.7. the boot a correction and which is
60:22 of the gravity crisis we'll learn But 2.67. Identity of parts.
60:28 yeah. So this is the that's very well behaved data set. How
60:33 samples did they had? What do say? Uh So 3334.
60:44 334 I guess. Yeah. So a lot of savage And the
60:50 So they're saying the mean is That's um medium rather is to question
60:57 mean is 2.74. I've got the ones. Go back, go
61:00 go back, go back. that's the same. That's the
61:05 This is a little different. So means 2.74 standard .47. So,
61:12 it can be low density. What it lower densities? You can have
61:17 erupted the salt their best killer. have bubbles in them and stuff.
61:24 that will lower the density. That's that's what all this nonsense is.
61:27 like I've modeled seamounts in the south . They have like densities like please
61:36 on the ocean floor, but they this kind of dense okay ball ranges
61:44 bulk density for rocks with insufficient All right. So, in other
61:47 , no, no more history. here's the range and hydrate 2.8 to
61:53 . I'm just gonna circle on a of these. And hydra, that's
61:57 precipitation. Right? So, when you know, in where you
62:01 like in reasons like salt is you can also end up precipitating an
62:08 , which is modus We're salt Right? So 2.1 or 2.2.
62:14 used 2.16 in the industry typically. No. Does it sound but it
62:20 also precipitate, you know, and 2.8-2019 for chips. So the chips
62:26 in here. There's no chip Okay. And then of course,
62:34 can look at some uh carmen's don't limestone, 1.5, That's really very
62:42 again, that's because this maybe this , you know, limestone that,
62:49 know, that is not very This might be like limestone with corals
62:57 stuff like that. And I think close to some kind of change.
63:03 2.7. Okay, let's look at . Under cemetery shale. 2.062.
63:13 that's again, that's really very, just depends on it's compacted and
63:18 alright, let's look at some. So these these are metamorphic rocks.
63:25 2.59 to 2.84. That's like lower 2.673 point one prototype. That's like
63:35 rocks 3.1 point 274. So I highlighted the ones that are, that
63:45 really kind of more common for me catch my eye. Okay, now
63:52 stances from Sharma, another source Sharma . There's a, there's a newer
63:59 , I think it's 81 or But sandstone here 2.152 point 42.73 point
64:08 granted. 3.2 point 5 to So just kind of tracking our
64:13 Call me index rocks. Just for edification here, we're looking to get
64:20 And 211. Okay, California this is a handler Bob sheriff,
64:28 of them um sand stones, So the average 2.35. And then
64:40 okay, they have wet and dry granted from Salford uh 2.5 With the
64:50 and an average of 2.64 assaults? 2.99 average. That's really high.
64:57 really really high. That's a 76 . Okay, 1988. Another
65:06 So here he has a bunch of stones from different parts of the
65:10 different parts of the United States. there's some great Britain Switzerland but mostly
65:16 U. S. And To see is a high value 2.17 down
65:24 So sedimentary rocks can be more very you can imagine because they can be
65:30 levels of compaction. Different companies with units. What am I looking at
65:37 ? So this again, this is going like chalk and marble. So
65:42 are different formations in Edinburgh is very formation out in West Permian basin.
65:51 it's co evil with what we call the NOX the NOX like in
65:57 Um Yeah, but so these are carbonates, um marble is a metamorphic
66:05 but I guess Metamorphosis Card, it be anyways, densities, saturated,
66:13 density 2.75. So these are 2.26 the lowest one I see here up
66:20 2.8. That's really, that's really . But that's the total lights,
66:27 the lights are gonna be more Okay. Glenn roles in texas.
66:35 , So just more examples. You use these as a resource I
66:40 So I don't have a shale placed a slate. So slate is a
66:46 . So where's the slave show? are all everybody you all just
66:52 Um 2.4, is the lowest one see here. 2.66. And then
67:02 sand, clay, gravel. And this is very loose, shallow
67:05 They're all very light, but at , just under two. So,
67:12 you would imagine, because they're in surface, they're not compacted at
67:18 Okay, granted they say mean density , which is really consistent. The
67:26 is 2.5.8. So that looks consistent the other work. All right.
67:33 what is all this stuff? What I doing going? So, I
67:36 this little summary Carmichael C. S telford at all. T
67:44 Right, so sandstone means two x - 2.42. And for each of
67:53 , overall the sandstone has two point does that fall on our graph?
68:00 about here. That's pretty good. all those different sources, Granted from
68:07 those ones. Average 2.67. well, granted. uh it's probably
68:15 averages 20 little bit bullish. Carmichael , You said 2.66. And then
68:24 was salt 2.96. So it looks looks about right as well. So
68:33 this this is kind of some good to kind of keep in your head
68:38 you're thinking about these rocks because these numbers that are pulled from man,
68:45 good. Good to know. And um Ok, so, Alright,
68:49 , hi, this is again average of surface and of course based on
68:54 referred was from mobile oil. So of samples, 617 2.32 for
69:03 2.42 for shale. 2.54 for 2.61 for specifically, that means
69:12 And they only have 101 105 cent metamorphic, which is pretty one.
69:20 And then But so basically, so so I think this is consistent with
69:29 summary from before. This is this from behind and they're just doing the
69:35 stuff. But they're kind of I'm showing because it's kind of a neat
69:38 to plot this data out. So going from 13 plus grass or cubic
69:45 and you have different kinds of So up here are these are all
69:49 are precipitated these salts. Um sandstone gap grows cyanide um miles.
69:59 I'm just my circle dollars, Right? So everything the three standards
70:05 been tracing through all this seemed to and uh right along. And I
70:10 that if you look into this stuff compare these ranges with the other
70:14 you would find it. This this is probably pretty good. Okay,
70:20 that's Hanson, that's just physically measured . You can also measure density in
70:26 , well, right. Um, is both density for every cubic centimeter
70:32 goes 2-3. And so this is and you see everything is just under
70:38 . Right? So things go from about 2.5 to around 2.5, maybe
70:46 , something like that. So that's density as a function of top.
70:55 so if you were to quite honorably data, what we do is we
70:59 of come up with a depth you know, layering structure because you
71:05 do things I mean is based on , there's no that density function to
71:13 into the layer. So you would block this out. I mean,
71:18 is one density to hear another another interval. Where is this
71:24 So and so forth. Kind of a lot. So another example you
71:32 convert from velocity, right? From laws. There's uh, there's some
71:38 by uh, Jerry Gardner used to at this university. He did a
71:43 paper 97 for gardener and gardener and know about that. Okay,
71:51 so jerry, I took two Right? So here's our you do
71:57 same thing. You can block that into into velocity region and then you
72:03 go to Gardner, I think I buried the next slide cross my
72:09 Yeah, so here's the table. has to figure out if Gardner jerry's
72:13 and you see for different mythologies, has a, the philosopher just has
72:20 velocity percent on this side and the gets me on this side, these
72:27 logs. But so you could, know, measures that you have the
72:34 here, density and he has limestone, dolomite and hydrated. But
72:40 also has this, it's uh 123 velocity to the corner of And people
72:53 that relationship still today. Now this published a paper uh, whatever 15
73:05 ago. Uh, and he could , here's Gardner's equation. So we
73:13 talked about, but then we also in another one. This is a
73:17 famous one, the Nathan drake which is after Ludwig, the name
73:23 . And that's just one that goes here and christian ceremony published the paper
73:28 just do compliments. Yes, their . Um, Godfrey, right,
73:36 freak some based on oceanic rocks. that's this profile here. What
73:50 Here we go now. Okay, . Um, right density from
74:02 so uh, this, this is same increments. I just showed you
74:10 , in the table. I have , uh, I didn't give you
74:16 spreadsheet, but this is stalled, for all these. I mean it's
74:20 in BP and actually um, the is that this snake drakkar we solved
74:30 analytically. So there's a formula and this is that's uh, feet
74:39 second. The other one was meters second, right? Yeah.
74:44 Now on sanitary basis because rock mostly . They as as they get buried
74:52 get more and more dense compassion. ? So there's a whole bunch of
74:57 that study this. And you could the compassion with the death density profile
75:08 presidency based on some exponential decay Right? And this is it.
75:12 in this case 2.7. Right? um Z goes to infinity. This
75:21 2.7. Okay. Now if zero it's c If Z is zero then
75:34 . So here it is. See sets the desk for zero
75:37 So if if you use minus 0.55 . Then you're gonna end up.
75:46 then the zero debt is gonna be . I I use this function.
75:53 used it to model onshore offshore Like I didn't model the whole top
75:59 land. So the land part. you can't even even 2.15 is a
76:05 too low for land, it's a too high for water body motion.
76:10 bottoms. But you can't use to different density because then you have a
76:15 at the coastline and that would look . So so I use this
76:19 So I use 2.15. Used to C. Sets the minimum and then
76:27 . Is of course in in depth kilometers and K. Is the shape
76:31 this. So um this one uses minus 0.2. But if I use
76:39 .4 U. Shaped this will go this. Everybody's .1 shape of.
76:46 what you do is if you have bunch of wells you populate, make
76:51 scattered clouds as wells. And then just use this function you diddle with
76:57 gentleman to see and the first So you figure out this range and
77:03 you play around with K. So get the best fit kind of curved
77:07 then you can apply that to other areas when you're modeling. Yeah.
77:15 . Now here's an important thing to salt salt is like the fluid is
77:23 . So that and and its density the industry we used 2.1 cents.
77:28 everyone recognized it could be a little be, you know could be but
77:33 a dirty soft. There might be sort of mixture of some sentences.
77:38 . Um What that means is that shallow sediments are gonna be lower density
77:46 the song. And but but mostly sediments are gonna be much higher
77:55 So that's what we call a crossover . The stash alone and it's typically
78:01 1200 m below the poverty or about ft. That's a good number to
78:06 on. You never think about But it's so what do you
78:11 This is an old paper? Anything but it really illustrates this very
78:16 Now they're doing this as a function d right? But it still it
78:21 worked. You can just think of in terms of salt is beneath the
78:27 depth and as as the height of salt crosses it's above the cross over
78:32 depth you start to see this. this part here the nominees broad part
78:38 being produced by this thick deep low contracts. But the upper part is
78:44 produced this bit here being produced by shallow party. So you have this
78:51 anomaly that shows you that's that's a anomaly for salt. Sometimes here's the
79:01 . Sometimes it all could be done but you could have right, it's
79:07 high intensity it's precipitates another middle. that could also be produced by so
79:15 could be two things, it could the salt is telling you about the
79:18 it could be this cap right on of that song. Okay, okay
79:26 I have here a little model and I'm gonna have I'm gonna show you
79:31 example of a two dimensional cross sectional from the literature and I like this
79:36 because I don't know if you've seen seen this favorable versus up it's pervasive
79:44 was great things man and everybody likes time I complain about this, people
79:50 well he's a nice or or or they know him you know I know
79:56 a really nice. So this is they always say that? So that's
80:00 of right? But okay, so okay, so he has this idea
80:05 he says that the breakup now this the breakup of this is this is
80:10 this is before Panji. So he that he can map spreading segments and
80:22 from, so there are now beneath Appalachian and I think that's just
80:30 I mean that's like saying you can the bridge and transforms, right?
80:37 just defies logic. So um and and plus there's a there's a it's
80:47 rift. So it's a special powder they're just dead end. They don't
80:52 . Um So, so this is risk which which required some sort of
81:00 thought or some sort of even oblique . He's got he's got extensive going
81:05 way to represent that's not physical Right? So I think, and
81:12 say, okay, so here's of course there's the Mississippi investment.
81:18 are all rest bases that form with . Okay, so these are these
81:26 protozoa and Cambrian teachers. Well, I think that and this is just
81:40 brief extension together because because I just that's just that anyways like I
81:54 but yeah, anyway, so it's . So here here's this feature laying
82:01 top of the graph, his same . Um here's the now this was
82:07 in pennsylvania with the collision of south and africa. Right? So this
82:14 this, this popped up at the time central basin platform. You've heard
82:18 before, it's in the middle of Permian basin. Um you've heard of
82:23 ancestral rockies. So those those you look at but the ancestral rockies which
82:33 oriented and which is which is where Oklahoma used to be. But then
82:44 inverted. He's all for intensity with of America and there's right, but
82:55 these pictures were Denver but the Mississippi see is high, high, that's
83:02 the rift, this is right, not here, that's the rift and
83:06 the wrong trough comes up, comes through here. Yeah. Anyways,
83:15 the graph and then here's the view so there's right, there's they model
83:24 slab, Right? But he's here then the collision of Africa and South
83:33 Gun one. Now um the slabs it this way because there's no
83:41 that's why we think the the other because and here's a little mom,
83:49 think this plan's a little flawed. this is 25 km and they have
83:56 have basin sediments going down 25 there is no base that people in
84:01 world that is not physically, 25 on this planet, it's just not
84:07 . Okay, the deepest basins on planet are 16-18 there's no there's no
84:17 face. I mean there are some are as deep as nine, maybe
84:21 , but most time based seven So okay, so that was 25
84:28 . And then they have a whole of different things. But see I
84:31 made a model of that and I , well you know what actually if
84:35 just use some reasonable dents, you have to have all this complexity.
84:40 can just model this way. I think you can model slabs,
84:43 argue they're not easy to model, that Dennis had some really elevated
84:50 But yeah, so I think they their their model goes like this.
84:56 I think really this is kind of to my my attitude about modeling and
85:03 using the same density control that he in this paper. So my idea
85:10 is you only have. Alright, um All right, let's talk about
85:25 mechanization around. So rock magnetization is more complex dense rock samples remnant and
85:31 . So they can be induced. can be magnetized by the inducing field
85:35 also they might carry some remnants from previous mechanization. Feel about that.
85:39 heard about that. Okay, Alright, so rock school Um typically
85:45 less than 580 500. Once they're to the point where they capture the
85:53 uh magnets, if they can do . If they had minerals that can
85:57 magnetized, they will capture the inducing orientation. Right? Well then if
86:04 rock moves around plate tectonics, Blah Blah slipped around or anything. It
86:11 it will begin to be magnetized by new industry but it will retain it
86:18 retain some of the original organization that's remnants. Okay. And there can
86:24 primary readiness. There can be secondary to get the picture right because rocks
86:29 a long time. Um Alright, it can be highly variable even at
86:35 scale there can be reversed magnetism, remnants. Like sea floor spreading
86:41 You heard about those? Those are those those are reversed magnetize the ones
86:45 are pointing the wrong direction. So the opposite. Don't be wrong but
86:50 the opposite direction. Okay, so Maxwell again, there are two kinds
86:54 magnetic fields of the field and the that we talked about. Um They're
87:01 to one around. Again, the abilities will be probability. So,
87:07 there are the common magnetic metals. two groups according to charlotte. There's
87:12 iron titanium oxygen group, F E E two, S. E O
87:18 203. That's a turner system. is an iron software. Okay.
87:27 That's kind of why I'm not gonna that. Alright, so the types
87:31 19 was dying. And that's where . The little diet polls are actually
87:38 up in opposition of the industry, is dying magnetic. It's weakly
87:44 So but but the little things, little that can oppose the inducing
87:48 Okay, this para magnetic which is small field is induced under the inducing
87:56 but it's tiny and it's really insignificant us. We don't care about the
88:01 we want. The one we care the most I say worry about is
88:05 alike and that's a product of spontaneous is very formal for pedestrian. So
88:11 you have a rock with arbitrary domains but once you hit the feeling
88:17 magnetized and induces your direction. Okay here again is our strongly magnetized our
88:26 magnetic source. So run in So as I said is a current
88:33 of the rock independent of the applied so that once ahead once it gets
88:38 primary mechanism is gonna hold on So then after you rotate it then
88:44 I said you have some you have combination. And basically the magnet measured
88:49 is equal to the industry field is vector of Plus the remedy. Very
88:57 , very easy to understand. Um actually like 14 but I'm just gonna
89:05 70. So run and mechanization, ? So what whenever you mention accusation
89:14 all all it's called the batch of right? These are all but there's
89:21 is thermal rent. So this is in rock school below the period temperature
89:27 a. Okay. There's a So that means grains that were previously
89:36 but they're forming there there they are a component in a sedimentary rock.
89:44 will align in the field direction, ? There's crystallization or chemical remnants so
89:52 acquired at the time of new creation growth of crystallization of magnetic grains that
90:01 will retain the remnants and as long they're below the curie point. And
90:06 you have a remnant magnetization tabling, pizzo remnant. So that's under mechanical
90:12 . So if the rocks are they can be magnetized on that one
90:17 reverse. So that that acquired And I can't think of an example
90:23 this is in other words, there's , random mechanization that is acquired under
90:31 tension. So lightning strikes. So you can be then there's
90:38 This is a long term explosion to a nice. So there's lots
90:46 different kinds of remnants. They exist . Okay, let's let's go back
90:52 our favorite three little rocks here, granted. And best salt. And
90:58 can see the magnetization. So let's susceptibility. This is in micro
91:05 These are humans island. There's in literature, there's people with all different
91:09 of uh units, but it's also sedimentary rise. They are effectively not
91:19 or metamorphic rocks. See how tiny are. They're all down here.
91:25 think the nominal value people use for rocks is 70 In an animal.
91:32 you solve this -10. But igneous . All right now this is 600
91:40 typically use about 2000 grants and for microts this this is 6 47.
91:50 pretty low 25. That's, that's low for uh Okay, so this
91:58 from dobbin and savage. Let's Do I have some more? Of
92:01 I do. But back to So they had Sansone 230 samples um
92:09 of the four avenue micro. So is this is 10 to the minus
92:21 . No, this is this is is tantamount. That's um Michael
92:24 D. S. Right, So 0 to 1665. That's a really
92:29 value. Oh and then um but of you should see are pretty
92:35 I don't know anything about that number 1,000 4000. I believe that.
92:40 was wretched. And then they have samples here, like Minnesota, Oklahoma
92:46 so forth. They had whatever they . Sure. For samples.
92:56 100 to 800 beds. I Okay, the salt. So 2100
93:04 that 100 27 samples 900. That's low, 84 80 400. Now
93:11 talking like that 6000. That's Some of these in Australia.
93:20 That's extraordinary. Um 20 900. what what what are you learning here
93:27 this stuff that susceptibilities are all over place. There's no there's no
93:34 Wait. Right, so what we're at here, we're looking at
93:37 this is the salt continue. Yeah. Okay. Um Now this
93:46 sharp granite. 22 40,000. I don't believe that because I had
93:54 model stuff like salt 502 £120. extorting sand stones 35 to 19.
94:04 would never give it that high but I like 35 35 to 70
94:11 . Let's see if I have some . Of course I do.
94:13 This is back to tell food. stones 016 60 that remember 0 to
94:22 to 14,500. So, in since the sedimentary rocks are very
94:30 sand stones are pretty high in major . Assault gag rules. They're very
94:37 Megan. That makes sense. The oceanic rocks are full of iron
94:43 manganese and you know, granted are , there's a high degree of
94:50 And and uh so they're not gonna left. Okay, so we're going
94:59 to dover and savage sandstone 16.8 25 - 2700. The south.
95:12 bad. Um This is a this kind of it's a nice exercise because
95:18 see how different everyone has. So, all right. Again,
95:24 Major. Right, So this is again, basic intrusive. Uh
95:32 Oh, actually this is right, is the range. That's the number
95:35 samples in those ranges. Okay, very few and more. Most of
95:39 in this range. And then basically grants. That's enough. Look at
95:46 . That's horrible. Um sedimentary. , most of. Alright. Um
95:58 this is he has decent charts in book assault acceptability. Uh Right.
96:07 This is so the conversion from I. One S. I.
96:13 way S. I. Is I know what university you have to look
96:20 S. I. Conversion or. , I gotta look that up because
96:31 that's weird. Alright. So but a relative thing. Right? So
96:39 is in this range grants are in range. Perhaps there's no sandstone.
96:45 this chart doesn't have no red circle . Way. Really tiny.
96:56 Yeah. Alright. This little This is from a from a thesis
97:06 a student here and the student modeled gulf of Mexico. You have these
97:13 anomalies. And the students said well can line up these features with
97:18 This is magnetic ated. So the goes from 1 to 43 2 or
97:23 22. They said this must be ancient bridge is supposed to be a
97:28 that formed when the basin opened So these are enormous amounts hundreds of
97:39 . When I saw this, I her I said those analogies cannot be
97:44 by starship because they're too big. must be produced by composition ship.
97:52 don't like that. They published us . But if I model this with
97:57 constant magnetic 7,000,003,000, which is kind high for granted This structure has relief
98:05 going from almost zero 2, That's not physical. There are no
98:16 not. So the thing is is big and when we get into
98:24 I have a I have one slide I say to memorize and that will
98:30 relationship wavelengths and amplitudes and how you think about this. But that will
98:35 that will be anyways. Uh If tomorrow, maybe it'll be next
98:40 But anyways this is a pitfall and related to rock properties. When you're
98:48 and big, it's going from minus 32. That's that's five. I
98:55 it's 303 100. Uh Anyway, a pitfall. All right. Now
99:03 a thing we call it a ratio that's the ratio of remnant mechanization to
99:10 mechanization. So the bigger the values the stronger the remnants. Pretty
99:15 Um So this is carmichael. This collin burger ratios for here's basalt.
99:25 kinds of assaults ratios ranged from 15 over 100 82 57. So,
99:33 burger ratio. Um uh Whatever. to write that would be 2-1,
99:43 it? That would be That would two times. That would be one
99:48 remnants. Two parts who two one part induced. That's a
99:54 So anything over I would say anything a half is important. Right?
100:04 over a half the support that we to. That would be a third
100:07 the remnants. So Grant Sedimentary rocks than .1 because they don't quite often
100:16 don't have, you know century. . If if there all the church
100:22 bases on around around this around the . You know those they're all in
100:27 pretty much cost to an inducing Okay. Um graph of metamorphic and
100:36 rocks. So here's Heinz again one these remnant dominance and induction dominant granted
100:47 saying their introduction. I don't believe uh Simon, I believe this,
100:52 I think why is that? I . Yeah. Okay okay uh
101:05 So here's magnificent ability. Okay so are different, well is like a
101:17 print effect. So these are these done. These are all mantle
101:23 Okay, intensity. And then the . Oh yeah of automatic rocks and
101:31 rocks and metamorphic. So automatics are mental rocks. Okay so um the
101:42 example is um of Connie's murder So this is a study. They
101:49 some R. O. V. . So they had a they had
101:53 deep a deep source of instrument I . It just motored around the ocean
102:00 here and they took some samples and calculated races of 1 100 -
102:09 That's really hot. And this is , this is in the Okinawa trough
102:15 . So Japan is there Taiwan china . So let me I think I
102:23 some notes on this. Yeah. the equivalent source inversion vision model statistical
102:34 . What's the result here? So they inverted these data for
102:44 So you just have a layer and just they have the total fields.
102:49 have the data to calculate the magnetic from the field. So here here's
102:57 inversion solution. This is in uh in susceptibility in F m. I
103:06 the conversion from that 1256. So m 1256. Now it does.
103:14 this ranges from -1202 plus Uh 1500. My procedures. So not
103:29 highly. Um Then this one is annihilator and that that's just a function
103:37 makes this all positive. So this their final magnetism organization. They want
103:42 have all positive values for whatever. don't think it's really important. But
103:48 , so this is the shape of magnetization of the rocks. And they
103:54 the I guess that they used to they used to call just supposed to
103:58 a confederation. Rocks indicate high colonics . So the summary for density and
104:11 for density rock samples from rock logs, conversion from philosophy and estimated
104:17 compassion lots of different ways. Megan basically rock samples and I think they
104:23 susceptibilities tool that they can put down . Okay, for density sedimentary rock
104:29 range from 1.9 and 2.7 salt 2.6 higher. And of course you have
104:36 cross over that 1200 m crystalline That means that is 2.7 you know
104:44 in the upper upper continental crust, upper crust. And so for magnetic
104:55 . Some of the rocks are essentially magnetic, effectively not magnetic one.
105:00 to christmas rocks, hundreds, 200 units. Amazing assault gathers thousands of
105:15 run the magazine several types and contributions very specific. So that's the summary
105:25 density and magnetization. That's a good to know. And and you
105:31 I don't know, I've gone so . How long is this supposed to
105:34 to? What should I do more ? Well, it is a lot
105:53 because you know, I don't have I don't have people interrupting me and
105:56 not okay, actually have a question you out of curiosity because I remember
106:04 when I took a class with doctors he was talking about whether or not
106:11 maybe entering like a polar reversal. like what are you, what are
106:16 thoughts on that? That's the timescale reversal. So what's done? I
106:34 , you know, the long normal that. So between 121 roughly?
106:43 for 80 million years ago, there no reverse. They call it the
106:50 things and during and then between Like 21 60 that is that Jurassic
107:08 There is what's called, there's there's cretaceous negative class. I just told
107:13 about those from 81 to 1. there's also something called the Jurassic that
107:18 something but that wasn't because there were funeral versus that's because there were just
107:25 few reversals were very fast and the strength is very weak for that.
107:35 , you know, it is you know, who knows? But
107:40 mean, it's just speculation. I not something that I think a
107:46 So maybe just some, some literature that. I have a friend,
107:52 of my colleagues he worries about, he's looked into this, he's
107:59 he likes to talk about, but not something like not good. So
108:08 all right. So, um, , any more questions, why don't
108:13 flip through the slides and you see we can stop and talk about it
108:17 that way I won't feel like I'm . So no questions on,
108:21 so wait a second. So, . So it's next saturday interpretation rolls
108:31 film, there's a single slide out that will right, right. Say
108:38 because whenever, once you memorize that for the rest of your life,
108:43 you know that information, you'll be to look at any grab and say
108:49 , tell us about. So, . So this is where I
108:56 this is the stuff that I teach dr is these these three lectures
109:02 I split it up in the but, but yeah, um,
109:08 , I have a question about it . So is it a four
109:13 So I don't think so. I I'll just write, you just write
109:18 exam to you just taking it at . So um I just said it
109:24 you and you just you know to that that even you know and I
109:30 the same thing here and then if we get that and I hope that
109:36 organized stuff. But if this I don't know this week, I'll
109:42 you know. But if this happens I can then I will, you
109:48 , we'll do the exercise together. will do the you'll see the
109:53 Okay? So then you just have go to work through and through the
109:55 . And I want I mean the I work because I'm not so much
110:01 want you to answer. But what more concerned is that you understand if
110:05 get a feel for the kind of and magnetic contrast produce different anomalies.
110:12 what I think you did the right? Did you like it?
110:17 know very well. And I think just it's just designed to fit with
110:25 data. Right? See that's one . Did you get a good grade
110:30 it? Yeah. You got you the model. Perfect. Okay.
110:37 right. I mean, but some don't some people like they tend to
110:44 take this personally. But, my , my opinion, people that have
110:48 a geologic background do better in my then people would just straight up
110:55 you'll be fine. You gotta get here. You have you have a
110:59 challenge. But a lot of they have an undergraduate geophysics and they've
111:04 no job. Some universities do it way and there they struggle because my
111:12 really you have to understand something about . One more question about. So
111:20 have final exam because according to the dr so we have a final exam
111:30 February 14. So do we still that one? I thought it
111:38 What's 10? The 10th? It's 10th. It's Wednesday the 10th.
111:44 tenses friday so. Oh right right . Um Yeah Final 6-15 on the
112:07 . Yeah. Yeah. Oh I'll it, I'll fix the schedule.
112:14 god. Um Yeah, I don't that's frank, that's frank.
112:37 cause our last class was supposed to Friday and then I take the final
112:42 , I mean I could just take final um Yeah, I don't know
113:00 to do, but So there has be something happening on the on the
113:07 . Okay, so we can actually the schedule then? Yeah, Except
113:15 . Yeah, I know this is , but the ones in the
113:19 Yeah. So I could. All , Okay. Alright. Anything else
113:24 this thing? What else did Alright, so alright, so I
113:33 through this history blah blah yada yada . And then uh this is a
113:39 is a little, I mean I need to rework this slide because I
113:44 potential enforce potential enforce and um I that's okay But what's important is uh
113:54 know, is really these boxes on slide. I think I think maybe
113:59 need to do that slide over and of course this is this is from
114:04 rick's book and uh I think that's . Can we go over these slides
114:11 um starting here. Okay. yeah, yeah. Here we
114:29 Let's start here. I think it's to start because you're talking about the
114:34 is a magnet, right? So have to north's different from magnetic,
114:38 know that from your field, And the field at the polls.
114:44 polls is burning and the field of magnetic equator is horizontal everywhere else It
114:53 . So it produces a symmetric high , symmetric low here. Then it's
114:58 combine those two shapes everywhere in Yeah, that's where you have the
115:04 between here and here. Right. then the field strength inclination declination.
115:15 right. So at the pole again high. Either pull north or south
115:22 think equator south to north or north south because it's symmetric. But is
115:27 going south and north oriented in a south direction. It's going to produce
115:32 symmetric low at the magnetic equator. in the northern hemisphere, This is
115:42 because you have an anomaly high low . And the source is directly beneath
115:49 . The maximum gradient. Right? you know, it's in the northern
115:55 because the high is south of the loads in the north. Right?
116:07 think about it this way that high you go south in the northern answer
116:13 you go south, this low has migrate to be over the that's what's
116:21 . This shape is changing such that actually like a face face. And
116:29 in the southern hemisphere in the high north of the source. You can
116:34 tell what happens for your in once understand it. So in the three
116:40 . This is just showing that in D. So if you take a
116:43 would be like symmetric high the cube the is the source and it produces
116:49 symmetric high pole northern hemisphere and the is always the same such a
116:59 But then as you go south from north, the high everything starts moving
117:04 with the direction, so now you're degrees inclination C. So this high
117:10 shifted down to here and there's a developing on this northern flag,
117:15 You go further, that high starts lose, right? See this is
117:20 amplitude and this high is losing it that amplitude has been Consume this
117:27 right? You know, first off 30°. Now you're losing a lot more
117:33 to the high but your on the and then if you keep going
117:38 you end up with just a see how that it's like it's like
117:44 law was consuming farming and getting bigger bigger. And then of course Southern
117:51 the same thing. Just the other instead of as you go, sounds
117:55 you go north, col 60° The saluting amplitude, lowest gaining
118:03 30°, the lowest gaining and losing And the high, the lowest getting
118:10 to end up back here. That sense. Visualize that. So this
118:19 is just interesting. The stuff on . Did I pass anything that was
118:23 ? No, no, no, like this little study. But uh
118:32 else did they go over? Uh ? I think this stuff is pretty
118:38 . It's just I just wanted to you that there are a lot of
118:42 values. Um you know, you , people measure these rocks and a
118:49 of different uh samples values to I went too fast. I gotta
118:59 slower. It's not understandable question about . So why don't you just use
119:08 low pass filter too? You mean block out these things? Because you
119:21 to first you have to have sharp , right? Because you want to
119:25 it. But if I blow it would be. And anyways,
119:35 mean, I don't really work with don't in this kind of stuff,
119:40 definitely someone will send you a file LS file and then we'll have robi
119:45 in it and then you can plot . Typically what I do is I
119:49 do a scatter plot of those and just block them out like this.
119:54 just live on so I don't I don't have an example of
120:03 No I don't I've used sonic check shots and velocity conversions. And
120:11 used uh three I'll send you the spreadsheet and I've. Yeah but yeah
120:28 used this one's not just I use one most of the time and then
120:33 I use this a lot. This of relationship that's just informational. That's
120:39 just whining. Um It's an interesting . I mean it's too calm.
120:44 think your models to come. I you can make anything up if you
120:47 . Right? But I mean they have data to support small. You
120:51 have it. It's just weird. then we talk about modernization and then
120:57 types of that promise again a lot different sources. Um Then I think
121:13 showed you this pitfall and Collins were . Uh And then the school
121:21 It's kind of hard to understand. Yeah and sovereign I guess.
121:32 I have to work on. I know if I gotta add material.
121:36 need to add material or just go explain it or something. What's the
121:48 left so far. Just like a and
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