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GEOL6358 Terrigenous Depositional System - Day1 02-17-2023-Part2
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00:00 And there there. Okay, um we look at the role of sediment
00:09 , um and some of the references rely fairly heavily on again, you
00:18 see those as reference. Now, spent .4 summers working in delta and
00:26 reason I mentioned that is that the was to have input for the possible
00:38 impacts of offshore drilling sound. And reason why the delta was important in
00:45 because it supplies sediment to the And so it is the sediment dispersion
00:53 is in part a surrogate for pollutant . It also sediment is a transporting
01:03 , particularly for plays for certain types pollutants, heavy metals, etcetera.
01:11 addition, by looking at the pattern deposition erosion, we can better anticipate
01:20 onshore pipelines might come on. And by looking at the pattern deposition environments
01:27 the age of the deposition environments. could do a better job of looking
01:31 the world from a force in terms which areas um more or less prone
01:39 . So this was not an attempt create a deposition mark. It was
01:47 try to define the setting in which drilling could occur. Having said
01:55 it turned out there is a some differences in this delta and other deltas
02:02 are not ice influenced. So, you'll be getting pieces that as we
02:14 , Oh, Alright. Uh we about seven ft sword institution in
02:28 We talked about sources to say in sediment routing system and we're looking at
02:35 over time scales to basically translate into history. When we look at the
02:47 influencing that source to say on We need an apology mainly do solve
03:02 the biosphere, which is important in storage area and implication and affecting settlement
03:11 this same. I'm Cyril wave energy supplies in affecting the redistribution in the
03:26 . So we go back to this source transport deposition. Except of
03:34 in reality it's never so simple. for example, here's a Subsys within
03:42 to sink. You've got erosion of hill, that position of Kalu
03:46 Um and Faith. Here's the erosion the goings deposition of Faith source to
03:57 within that larger. So some of settlement is actually sequestered here. Never
04:04 it to the coast. If we at the source of sink system in
04:12 , you find there's a lot of . We're for reaches country. You
04:24 say there's a complex assemblage of sources a large draining this. Then even
04:39 the settlement get some green setting, can be redistributed, you can get
04:45 the shelf going to submarine fan, we can add some settlements to be
04:51 off the slope. So when we of work on our source to
04:58 it gets pretty complicated here are different . There are different states in your
05:08 here plus other sources, most of makes it in this case to the
05:14 of fan, but some of which to the places as well.
05:25 I want to focus on for a . The amount of settlement it's or
05:30 rate of set that's coming to any of that system and what the very
05:38 looking at by composition. How what being transported in what that in term
05:52 important with respect to the sequence species , strata, graphic protection and constraining
06:01 supply is important. First photographic forward predicting reservoir presence and quality. If
06:12 look the north sea turns out changes sediment yield. With the principal control
06:18 the sequence developed. You may have or recalled that when sequenced photography first
06:26 developed it was strictly use static stealer control the path. But here
06:35 seeing sediment supply is the single most girl and that reality both show temporal
06:47 spatial distribution of sediment. The state whether that you got potential reservoir faces
07:00 the term is the nature and science those deposition systems. So cinema supply
07:07 a huge independent variable. It's cycle . Oh and we're gonna see it
07:17 this course. The role of Sadam and affecting deposition. It affects the
07:26 of transgressions and regress we saw that that diagram about sediment supply versus
07:34 In the diagram. The difference in between transgressive and regressive systems. Remember
07:43 for a constant cee lo we could transgressions in the delta and regressions.
07:50 in the delta. Transgressions on the depending on the lateral change on the
07:57 line of the rate of setting the . I mean if Louisville decision,
08:03 are all things that we initially think driven by sea level and sea level
08:14 but are significantly influenced by sentence And that's what's referred to here.
08:23 you think of the various rainfall bench basic basically automatically controlled drainage area,
08:37 belief and social base level actually is base level and be affected by tectonic
08:50 themselves. So these are the drivers produce the sentiment that creates our vitamin
08:59 . Rocks of interest. The one that's missing is human activity. So
09:12 why you even bought because in fact rock that you're interested in is petroleum
09:23 is going to be older than any human activity. The white bother to
09:31 this less other than maybe some academic for what? General volunteer. But
09:39 a practical reason for including this. you think of why I'll give you
09:53 that is most of the studies that used to infer about past relationships starts
10:01 the study of the President and so we have to do is be able
10:08 extract human influence. Yes. We to be able to look at the
10:18 factors that affected your your up. we'll see that in more detail
10:26 Now there's a terminology issue but the supply. You need to understand the
10:31 load which is the rate of central tons for you, oops and their
10:40 year. That is the rate per area times per year through Barcalounger.
10:50 Hector. Can you think of a why you might prefer one term versus
11:01 and in fact we use both because different circumstances load is more important than
11:07 or yield more important. So what sediment load? Total amount. Can
11:14 think of a now let's include modern include things that might be going on
11:29 . Why might you want to know amount of sediment annually? Your water
11:43 , you're in charge of the sediments the water supply for Houston texas.
11:51 managed lake Houston. Why would sediment because the sentiment coming down the river
12:06 filling up there is real and so has to do with the lifespan of
12:11 reservoir. My first job with S. Geological Survey was a resource
12:19 and there we had these small reservoirs santa cruz Mountains that filled so rapidly
12:27 set up. Yeah we would basically out annually with the atomic senator figure
12:35 how fast and then literally we drained lake, bring in the bulldozers and
12:41 again. That's how high the sediment was relative to the area of
12:50 Now so sediment load is unique to spot. Okay sediment load as you
12:58 upstream presumably gets less As you go three more sediment yield is eliminates that
13:12 because it looks at the amount of for drainage area now where that becomes
13:19 useful is if you're trying to extrapolate compare study two different studies for different
13:28 . I've got one river here 600 miles. This 1 50 square
13:35 I've got sediment loads of each. different totally un comparable at least until
13:43 normalize it with respect to drainage They end up at least got
13:49 Now they may differ also. We the things relatively rain climb at least
13:58 the first cut. I can start compare different drainage basis. Now when
14:07 look at the seven, we have suspended loading result. Okay, the
14:17 room includes what's called wash load and suspension wash loads of terms you might
14:26 have heard. It's the stuff that in suspension and usually it's transported past
14:32 specific place until water doesn't move So it might actually be polyps in
14:39 flood face after the flood or in pro delta beyond the delta. But
14:46 not gonna be preserved within the channels , isn't it? Now, one
14:56 the things we're interested in with respect source to say. And also describing
15:01 amount of sediment that might be coming a base is the amount of lowering
15:07 the land by both weathering in the . So the material that's generated from
15:19 basically is that stuff. I just this all alone it's solid wood which
15:26 be bed load suspended. So those are the result of. We tend
15:41 refer to the dissolved load as Tds dissolve solid E. S. S
15:47 suspended someone. We don't have really good time. Bad load. I
15:53 Tbs just because I can't. It out that there's different types of innovation
16:01 therefore different types of sediment produced. chemical d innovation where we lower the
16:08 by totally or partially dissolving books better near the surface. Capes mechanical determination
16:22 we're physically eroding the solid material and can go on. Although the relative
16:30 of chemical versus mechanical denomination obviously depends part on climate and in part of
16:40 so if you look at chemical climate and then Rachel soil thickness maybe
16:49 intuitive but it affects the rate at fresh rock it's exposed. Okay,
16:59 you have very thick soil and relatively relief, you're only eroding the
17:09 weather and material. It is very soils and steeply your weathering the material
17:16 the soil and in which case it's longer chemical uh rock type. Obviously
17:27 biology types of terrestrial organisms have a effect. Now one of the things
17:36 we want to at least be aware is how do we measure this?
17:42 remember that the product of chemical weathering dissolved by science. So that's what
17:50 measure total dissolved total dissolved. Now turns out we measure it and normal
18:01 even low flow. Do you have idea why you might not want to
18:04 dirt floats? It's a subtle but obvious when I tell you in
18:18 , most of the water doesn't soak the ground, It runs off over
18:24 flow in low flow. What water there has made it through the soil
18:34 the bed. So if we want measure the rate at which water is
18:41 bedrock, you want to try to the water that you measure to water
18:48 has flowed through the rock, not that flowed over. So you're gonna
18:53 a completely different measurement and really irrelevant . Uh two chemical weather, if
18:59 measure during floods, if you look the sources of world's dissolution, world's
19:08 solids. Rather, Almost 2 3rd the soft onions come from 17 the
19:17 club area. So this is the and a quarter hard to dissolve those
19:29 rocks. It's now, I started at the water quality water chemistry.
19:37 rivers is pretty, very light amazon , total dissolved solids turns out most
19:48 the drainage area in sister thick. it's highly leached because it's an equatorial
20:00 . And because it's flat, you to be eroding just talk of
20:05 So climate has played an important They're gone. Geez no higher.
20:14 largely the effect of carbonate rocks in lies really hot 67 times higher than
20:26 audience that reflects carbonated and increasingly irrigation we're irrigating water in an arid and
20:41 arid environment. We're having precipitation of medical detonation, it's a little harder
20:56 measure because measuring total self politics literally measuring the conductivity of the water take
21:07 . There's a little more than but not much here. You're measuring
21:13 solid particles and we're trying to get rate of transport the solid particles.
21:18 , that's hard. So you can the sentiment world of a river to
21:29 that. You've got to do it a gauging station and you have to
21:32 it continuously for a while. Please tell you can figure out what's going
21:38 . You could also do short term accumulation rates. These are sometimes called
21:46 . So he's not the reservoir you're in. But the reservoir I was
21:49 in in the santa Cruz Mountains where looking at the rate at which the
21:55 is filled. Like it could be . You could look at if you
22:01 determine the time package. Uh they'll sedimentation if you're pretty confident sediment was
22:10 the delta bypassing delta. You could that. There are nuclear studies that
22:18 could use and finally degradation rate of accumulation studies that you could do.
22:41 . Yes. River load, anything give you a record A year to
22:48 lucky 100 years basically. How long did. So only water maybe a
23:00 100 years. Usually it's based on , metric patients before and after.
23:12 . Climate land use changes that you when we get into the larger units
23:21 longer time periods. You look at of settlement on the basis for volume
23:30 rock exposed removed by intimidation. They looking at tectonics. Land use is
23:38 longer a big deal in part because looking at thousands and millions of years
23:45 . And how about you look at sediment biden, particularly offshore the
23:51 Think that we routinely measure volume of sediment for different time, apples be
24:04 David and then infer from that something starts to sink. What we measure
24:16 a uh aging section, suspended Why do we measure that?
24:24 It's easy. We literally have to the line of suspended sediment at different
24:34 . Part times time, average velocity got to read. I say that's
24:41 . That's actually pretty difficult. And tend to spend time a lot of
24:47 trying to be able to extrapolate ways tying the sediment transport to the water
24:56 . That's another story, relatively The problem is, bed load is
25:04 to measure the good news is it's relatively small percentage, totally solid love
25:16 news is that's probably what we must in in terms of reservoirs. So
25:23 , we could measure it at the , but then we literally have to
25:28 a trap on the bottom and measure of sediment with very, we could
25:41 to take actively try to estimate by driven equations bed load equations.
25:56 now we can get the longer term studies or the innovation volume studies.
26:04 point there is that perhaps everything the . Now I said earlier that we
26:16 to be able to extrapolate water discharge . I mean correlate the water discharge
26:25 set in the district. Well, began with the stage that's very easy
26:31 make. It's literally a floating this . That information is sent to somebody
26:40 cares. Um 7 15 minutes. if we also have some guy out
26:48 measuring discharge during different elevation, we get the rating curve which relates elevation
26:56 water discharge. So that is a discharge reading. Mhm. Well we
27:07 also, once we've got that poorly water issue, major get a seven
27:25 . And finally, if we're really we can get it bad little
27:38 We don't have a lot of these fuel of these. That's what you
27:45 to do. If you got a Now we're measured or estimated. It
27:52 out it varies a lot. We we often Like I always use
27:58 I don't know any better. I 10%. Total load is Amazon is
28:08 . Y'all come on the river in , There's a huge variation. So
28:15 pays to know what is causing this . Uh huh global variation. A
28:31 have some other problems. This is measuring sediment load but water load as
28:37 . Water discharge. Did you sample rare event Turns out that typically half
28:48 annual sentence was during three or 4 floods. River we got three days
28:56 flooding transported more than seven years previously so long term records, hopefully catching
29:09 really high magnitude flood or what you . If you're trying to translate into
29:18 long term theological records and now we're to human activity. These are all
29:32 that affects the sediment. We'll just fine the first stage building the urbanization
29:45 . Mm I made a change in magnitude. This actually is here only
29:53 we're beginning to see people change Most of them said that makes it
30:08 the code, it's from rivers and all blowed suspended ability. The rest
30:17 not much wind and coastal erosion. it turns out then locally these are
30:35 , it's important in the way in Yukon delta and north slope ice is
30:40 factors controlling the way sentiment is restricted coastal deserts, swim. Coastal erosion
30:57 , it turns out that when we look at the amount of fluid real
31:00 that makes it to the ocean, lot of it doesn't. A lot
31:05 us trapped Yellow River, 80% of this trap. If we just look
31:20 the change of 197 Percent of change , 3 what 100 bees basically says
31:38 River today basically no longer flows into at the gulf of counselor. Therefore
31:47 Colorado River delta is no longer, are only a few rivers that actually
31:55 increased their sediment during the last 50 . And if you look at these
32:08 , oh, Have had 80-100% instead shut off by Dams. So what
32:17 measure today may have very little relationship what was going on even 50
32:29 And of course theologically we know there these buffers, these areas where there's
32:35 prior to getting in there. So reason why some of our rivers are
32:41 getting a small portion to the delta because of a damn, but because
32:51 lakes or subsiding basis, like when think about it, we wouldn't have
32:58 accumulations of fluid deposits. That sediment just transported through the transit system.
33:09 let's look at some geologically more So here we've got passive march kind
33:19 like what we are today, said and not necessarily texas, but in
33:35 acid margins economically induced subsiding areas, there's some accumulation is removing. Then
33:46 basically transformed into more don't. And of that settlement reworked, transported across
33:56 shelf makes it um shelf. Whereas in politics, some of reworking
34:06 Some of So what we could look is the pattern of I passed a
34:22 in each of these cells. Their mainly at that load, a little
34:30 of suspended, no maximum deposition dealt . Why is the offshore fish and
34:44 re working and redistribution the deposition. . Where's the ship trip beyond?
34:54 for a passive margin. Uh An tectonic margin might look similar except now
35:01 got and tectonic lee in this high . And so this is not a
35:12 think this would be our adult show again, would be our sediment april
35:23 and I should add was not included . This ocean ocean ocean come.
35:31 an ocean economy. You're gonna have queue four more years. Now that's
35:44 obvious when you look at this this might be the him alliance.
35:53 would be the Ganges Plain. This be the future delta. So here's
36:01 foreland basin got the little piggy back trapped within these through us. We
36:13 an inner Montana basin. But what we see is that there's a
36:20 of ways in which sediments intercepted and preserve and therefore of interest. Now
36:29 tectonic control. What about climate control example, racial integration. We know
36:35 really, especially during the playstation. we've seen alive relatively atypical um glacial
36:46 had ice uh times in the Global ice house stuff but it's
36:53 Okay, so that now looking tough better transport during the glacial periods most
37:11 the set of transport a little bit . Alright now it starts to warm
37:25 the appreciation passport pressure stops. We this increase of the only energy.
37:35 big spike. That's because as the found we have these big out wash
37:45 coming in and of course reworking of settlement including nurse, which is that
37:51 said and eventually with the interglacial period is not so great because we don't
38:01 as much exposed nation fluid policies, is getting warmer. So we got
38:09 and it's predominantly fluid. So we just in the last 18,000 years l
38:22 mount and type of sediment transport it change. How do we deal
38:30 how do we figure out the safety the animal? What we're looking
38:41 We know that there's forlan basis in and then accumulated senate we know they're
38:51 storage within figures and we know that delta Felix of increase for this
39:01 you know, there's a dipsy. , let's just see what's going
39:13 Well in modern starting here We've got reworking of these things from 97 I
39:30 that sediment is this is a high during the low statement the fans farm
39:53 little more active and then we're reworking delta. So when we look at
40:06 things are being stored during the glacial towards the positive in the today you're
40:22 most of the sedative foot plane reworkings most unsettling is in delta back then
40:43 this becomes important because if we look storage source to sink into my saying
40:53 got active position in active formation of sea fans. So what it tells
41:02 is that modern is not a very analog for my c the most and
41:11 max in part because there was not wide shelf and or because of that
41:23 tectonics. But when we're looking for analogous to our basin, recognize the
41:32 of climate into politics. Um, look at climate talks a lot about
41:41 , but look at the geographic variations big fires where areas on the other
41:58 , there's a lot of work being on analyzing our rivers are affected.
42:07 climate type fine, fine, And the hyper graph shape. It's
42:17 be one of the clues as to transport of settle. Now we can
42:24 this kind of global weather pattern. very simple. Yeah, basically those
42:38 areas here here are associated with down. Well in terms the air
42:50 dropped, they're able to own more . No ring when air masses uplift
43:03 is wet. These are the power and where less is being uplifted in
43:11 equatorial zone. That's the equatorial cons really calm. It's just the water's
43:20 up building. The air is going and not silence the donuts. So
43:25 wet, dry planet drawing and we look at that here. Blue is
43:35 uplifting air concentrate. Yeah, I'm here mrs I'm sorry, lack of
43:48 finding air fronts homer fronts one more has more really in the tundra and
43:57 regions. It's a desert republicans temperature attracts what you'd expect sme later who
44:10 heading towards? But evaporation actually is is low. My rainfall is
44:25 brief in the clouds. Evaporation is not where rainfall, these guys,
44:33 but we're actually rainfall is lease and got not the highest temperatures. But
44:42 lack of the other thing is notice fall of vegetation. There should be
44:50 to that has to buy biological productivity that's going to affect the chemical
45:03 So when we look at that, can actually look at the depth of
45:08 and the weathering products every time a , the almost 30 and my daughter
45:23 within that deep one with most of it is. We go from
45:28 altered bedrock to realize they overnight and a woman of the guard actions.
45:37 letter get up into weathering products in like texas, our maximum. So
45:53 type of clay we get at least the soil. It's the largest tent
45:59 by these variables and has a geographic . The amount of holder dog Saunders
46:13 the specific runoff occurs ends up, said you bizarre silence in the temperate
46:35 and here there's not much detonation going in the tropical award. Yeah,
46:48 noticed. So in these, those gonna see mechanical weather or not.
46:56 zones chemical chemical where the products were in the temperate zone. No
47:12 Now we see these global weather patterns and of course, one of the
47:18 we're interested in is can we infer the global weather product past. So
47:24 of our goals, if you one of our requirements is to be
47:29 to look at the geometry and anal distribution of the continents in the
47:36 of the continents at different times in past. And for whatever reason we're
47:41 in. Yeah, the human problem . Most of the erosion is a
47:55 sick. Most of the sentiments are because basically they're Well now let's make
48:07 point within this. Oh it Almost everything has been reached out to
48:17 surface. But you know the majority no whole lot what heretic dissolve
48:29 Mhm. It says here total I the question. Because what we see
48:40 the amazon is that even though you have mainly place that is the solid
48:50 , the dissolved solvents are to a extent depleted of ions because of the
48:58 that will very and Aaron you're writing , there's really not that thinking protected
49:11 , mainly sandy, whatever it is we had before. And here you
49:17 a mix of all which means you mixed clay sands and grabs. Now
49:24 one other thing you better got a of you have high rates of
49:36 Therefore you constrict them get into the . So what what is the role
49:43 belief? Well, if you look but sometimes it's scary the land three
50:05 . But then when we get into steep zones, That's where almost 3/4
50:13 the center. So so clearly the of relative relief is a huge one
50:22 determining the amount of set of being . We see that here in the
50:27 again, the envy sitting up in Or contribute are eroding at 100,000 years
50:38 now. A lot of it is there's carbonates, scales and a lot
50:47 this because so the combination pathology giving huge bias for sediments. It's all
51:00 , from the Andes 86% The total 12% of the area. Can.
51:12 when we look at this adam think particular looking at uh precipitation take that
51:26 put it as one x. So relief, aluminum. And here is
51:42 the relative amount, wow family. . No surprise if you have a
51:56 in the equatorial region, actress imitation the greatest well relief. Right?
52:10 you can begin to see how this , this relative relief combined these graphic
52:25 tell us qualitative, how can the of areas. The problem, one
52:34 the problems is most of our models our information comes from low latitudes ever
52:43 going towards high latitude targets like the . Maybe some day we're gonna have
52:53 look at how those things fear. what we what we need is away
53:09 . So one of the variables wealth , more area, relative relief we've
53:18 there and temperatures asserted. So this the ark And 75% factor to our
53:35 with six and 9, it's The problem is, it did not
53:42 into account geologic variations and human in . So there's a model here.
53:53 added to be fact pathology in the traffic officials. Human induced.
54:06 true. If we have that now have no. Now we have an
54:17 about the big, big forms, , geologic androgenic effects, water
54:27 area relief in temperature, what a climate and area, granny jerry,
54:41 tectonics, average basin temperature. we're trying to pay the class.
54:49 gonna apply these to an area of . And so this is what we
54:57 when you take into account of geologic anthropogenic factors When our Square 2.95 and
55:05 is the best equation we have to , but it has its limitations.
55:15 tells you the rate of suspended a river and a near seal
55:24 It does not estimate dead load of . It doesn't look at those intra
55:32 , all deposition areas in the areas retention. Would you, In
55:41 sometimes it's kind of hard to for example, determining drainage area.
55:47 , we can use equation that relates discharge area. Well, we've got
55:57 couple constants here. And if you pick an empirical costin's normally do look
56:06 the between Syria estimated the area match what fixed costs. Now, if
56:22 look at this, the area and down here humid here. When So
56:38 get an R square 2.5 looking at . If you look at varying the
56:49 based on the climate and Aaron is apple, which is no real surprise
57:05 if you're trying to predict water discharge area basin in a desert, not
57:15 surprise us not. But if we the climate, see if it's semiarid
57:22 human way, then we got it better where Approximate the area and flooding
57:29 the Big one. Of course. this gets back into reconstructing the climate
57:37 at the time that you're interested Jeff, this is the center
57:46 So here's a model towards the state . We need water seven insurance based
57:59 the I mean you've got another marriage of the waves. But when
58:11 when you do this model of which component, he sent him a
58:17 That's when you can match the The variables until tomorrow. I mentioned
58:29 and it's the input a lot with sediment portion being. Now there's actually
58:39 different methods that we use has to set influx. Yeah, The Top
58:49 is big. No, this is big fort and those are the
59:00 There's a mentioned one of those we to be more careful of. So
59:09 is a case study basically stores There are some things and it used
59:29 Carlos simulation, the determined sediment discharge at how it's very Yeah to come
59:44 with a source, Remember how much occurred last 18,000 years according to glacial
59:58 . These are variations in predicting. don't know man. Okay. And
60:08 his Children from different small texas Is 10,000 years ago. Good. That's
60:22 we don't have to worry about We don't have to worry about racial
60:27 . We're just talking about weather. ? Look at the variation. So
60:34 one of the hair trump measuring things . It's just it's a tough time
60:42 the GM or fix scaling or we at different components of source sink,
60:50 volumes locally, shelf length, This is the history books. There's
61:00 lot we have certainly action all of and this is the the paper that
61:12 introduce that concept the last at the model and it kind of is related
61:20 that sediment balance. Remember that? talked about where increased sediment increased
61:25 decreased sediment increased approach. We're here editor settlement input for Cambridge. It
61:37 there's a kind of a balance like red coming in april and it was
61:53 now that model works has a lot it. A lot of the building
62:02 related to calculating the alien ideology of at the with depth global lost six
62:19 kind of school. I saw something , these are just nice full
62:30 That's kind of hard to. So are very some of which it's a
62:34 complicated procedure, but when you look the inherent errors that follows an annual
62:46 and then when this is huge, in a plastic perfect fear factor.
62:58 naturally the week this just to show example, this is trying to reconstruct
63:09 from green size. The what I you can do it because using this
63:19 you need something but don't expect any . Mhm. So what I've done
63:28 try to focus on the role of supply in the larger story of source
63:37 sink and determining where you're gonna get and deposited. And increasingly, we'll
63:46 the type of sentence. And of , we've seen that this both tectonics
63:51 climate that determined the selling rate. there are a variety of techniques to
64:00 to incorporate or create that uh measurement put into the source of ST
64:09 So I'm gonna take a break Mhm. It's 3:45. Let's take
64:15 a 10 minute break and then we'll up the next
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