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GEOL6358 Terrigenous Depositional System - Day2 02-18-2023-Part4
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00:00 Yeah. Anyway, okay. I'm gonna talk about the customs
00:06 but the reality is that you cannot with lakes in isolation. You've got
00:13 look at the context in which they're the adjacent deposition systems and the structural
00:22 reasons for their formation. Now, actually a lot of good literature on
00:31 . But the one that this is of those cases where the textbook really
00:37 a good intro and I'm gonna be some of the chapters from the
00:43 including this one in the country. you'll see these names down here
00:51 in a lot of the figures, also notice there are a lot of
00:55 names because the chinese have really taken the study of the customs systems and
01:06 basins, uh to really the state the art at the President.
01:13 what is it about the custom Well, they don't cover a huge
01:18 today. Um, but they have the past, there are a limited
01:26 in the geologic record. So they're as well studied as other systems
01:33 They contain a large amount of important ranging from oil shales, we both
01:42 and reservoirs, uh, evaporate, rare earth minerals within cold uranium
01:52 So we continue to hold them in high esteem, in fact, even
02:00 , 10 years ago. Uh they about 20% of conventional petroleum reservoir.
02:06 , we really started looking at the in petroleum systems much more in the
02:13 15 years or so. These are some of the areas where we've seen
02:23 oil deposits. So, in offshore , in the south atlantic, all
02:28 china, uh the outer river in Denver Basin, in uh of
02:36 US etcetera. So, we see studies from many of these areas,
02:41 areas uh Indonesia and china and that's the bulk of the petroleum is
02:49 from the custom source rocks. uh these are major uh fields and
02:58 increasingly a major area of interest. the first question I might ask you
03:04 , how do you form a And clearly you need a whole,
03:10 you could block drainage, blocked drains a river. I mean by a
03:18 that would be like uh ag for example, when the continental uh
03:26 sheets began to retreat. North flowing formed this huge lake, you get
03:32 by dunes, uh, river oxbow lakes, landside lava flows.
03:39 Grand Canyon was damned by lava flow lake for awhile, balts. Uh
03:45 got thoughts that would lock off the . Um Most of these though are
03:53 . Um and so if you want long live, like, you're basically
03:58 have to create a whole due to . Okay, um subsidence volcanic
04:07 racial scour really is, is a longer lived result. The great
04:14 finger lakes, but tectonic depressions, rift valleys, foreland basins create,
04:21 sacks. That's really where the bulk our lancastrian deposits in the bulk of
04:27 petroleum interests has occurred. Okay, , 90% other lakes are the result
04:37 tectonics and glaciation. The one of variables that's beginning to sound kind of
04:45 . Well there's geology or whether there's climate and hydrology which is related to
04:52 and geology, which is related to and time and biology. Biology we
05:00 with respect to shale composition, but is much more important with respect to
05:07 customs policies because of the role of productivity in lake systems. So this
05:17 says the same thing. It just a little deeper into some of those
05:23 geology and things like tectonic setting accommodation, space, blah blah
05:28 You can read it, it's all but um it's all important in terms
05:35 understanding the controls on the customs The control systems have some things in
05:42 . A non marine final assembly that of goes without saying no astronomical
05:50 Okay, that makes sense. But can't have wind tides and so you
05:56 have set up and set down during that can generate some interesting environments.
06:03 it's a reduced wave climate, but course that's because lakes are generally smaller
06:09 oceans. But we talked about the sea which is a lake or the
06:15 legs. You got pretty good wave . So wave activity is a function
06:20 the size of the basin and fetch wind over. So for the most
06:26 lancastrian deposits on lower wave energy that but um you can't generalize uh episodic
06:37 and it can really lead to evaporate exposure and related cyclical prophecies is the
06:49 of those very large non use, fluctuations in lego like like Malala in
06:56 east. Um It's the frequency of fluctuations is driven by climate, the
07:09 extent tectonic activity. Um And it's an order of magnitude more rapid than
07:17 changes and it can be greater in . Uh Usually you see an increase
07:27 brain size towards the border, fine the middle will show exceptions paleo currents
07:33 the center. I'm not sure I agree with that. Now. Um
07:38 local sediment provenance that is shared by fans, they both tend to have
07:45 small drainage basins and therefore the local provinces. Having said that as we'll
07:56 , fans and Austrian deltas can intercept and more larger and larger advantage areas
08:04 become larger and larger rivers and have provenances. And unlike marine settings,
08:14 you can produce sediment with a high of oil, but with waxy organic
08:20 , the geochemistry of lancaster in organics different than the geochemistry of marine organics
08:29 I'll leave that for the next course get into detail. Whoops. Um
08:36 need to think a little bit about different settings uh in which we can
08:44 a late uh the littoral zone. the term we use for marginal water
08:52 be the marine or lakes. Uh that's basically the zone to the base
09:00 way, let's say weight base, in this case is also the zone
09:05 mixing because that's of course how you . Um, and then as we
09:11 into deeper water below wave base, getting into the pelagic zone. We're
09:19 deposition a lot of the deposition from center. We can also subdivide
09:25 No, we can use this for classifications to just 10 to into the
09:32 zone. Photo zone is the depth which you don't get significant like
09:38 of more interest is the zone that that's dark below plastic has no life
09:50 therefore no primary voters synthesizers, with death. Yeah, there's a
10:03 here mixing, but I'm gonna get to that in a moment. But
10:08 called the epidemic. And it's basically transition from the upper zone to the
10:18 zone. And this is for stratification stratification is an important variable in allowing
10:32 material that settles in the zone to non oxidized to be in reducing conditions
10:42 allow it to match your it to and gas. Now, if you
10:49 at the organic sentiments here's that epilepsy again, Lord May or may not
10:58 on that later. But below the he has stratification in, tends to
11:09 greater than the rate of decay. it is potentially hydrocarbon sources.
11:18 these here are allergenic, they're coming the outside our sports water bloom detritus
11:31 here. We also have auto jenny that's basically from the softest living fish
11:40 plankton yourself. So the accumulation of bread sentiment is going to be a
11:48 of both allergenic and allergenic resources. a surprise. The allergenic door
11:58 the photogenic sources very dominated are gonna towards the deeper usually metal parts of
12:08 we see here, big ball describing zone fans, they stay here.
12:25 little unclear what's going on here. , I wouldn't know the hot
12:30 So, and uh these tectonic li zones where we have early rifting.
12:38 we not only have early lake deposits the alluvial fans, but we often
12:44 hot springs as well. And uh dr gravest talk about custom carbonates,
12:54 a little. Okay, well they're they're locally very important. Um in
13:05 there are some of the main uh sources and reservoirs in the sub solitary
13:13 , brazil's example. Okay, uh said that I'm gonna kind of pretend
13:19 don't exist because fundamentally I don't like rocks and uh I'll mention them in
13:26 , but just know there's more to and that's one of things I like
13:30 the textbook. I want you to . It's got almost a half the
13:35 is on carbonates. Right? So think about the non uh biological maybe
13:48 . Uh we still have the but now we've got a delta over
13:59 , some of that sentence. So density currents in some cases if there's
14:07 strong stratification, Let me just get pen going for a second. If
14:19 lake is stratified, some of those currents will float out along that stratified
14:27 and some will float as a clue the top. We'll talk about how
14:34 of these may vary. And of , providing sediment either from suspension or
14:42 uh bottom traffic uh related from that viel inflow, uh maybe ice drop
14:51 , a little volcanic added. so there's a lot of different things
14:56 can combined to fill that lake. , this is actually a diagram.
15:04 personally confirm in that. It still that delta sedimentation. It still shows
15:14 plumes of sedimentary gravity flows. It's the biological productivity. It also shows
15:25 that zone of mixing in the wave can cause erosion and re deposition.
15:34 , so depending on the size and velocity, a significant amount of the
15:42 in the lake can actually be um derived as far as the water.
15:54 have sources and sinks of water rain the lake, surface blow from the
16:00 and groundwater recharge from the influx. lose it by evaporation and evaporate transpiration
16:07 surface water exiting and groundwater reach being . So in short, that's what
16:14 in and that's what goes out and lot of what happens in the lake
16:19 the relative water budget. Think of like sediment budget if we have more
16:25 in than out, we've got a open lake, we have less water
16:30 that water out. We've gotta close . Yeah, we'll be here.
16:37 Water salinity certainly is a way of lakes from fresh to hyper saline.
16:45 I'm not gonna talk about that much . I'm more interested in some of
16:48 other aspects of it. Um We talk about open and close perennial to
16:55 pan, degree of stratification and last overfill the under field, overfill the
17:00 filled uh is probably the classification that geologists are using most today. So
17:07 focus a little more on that than we would have in the past.
17:13 let's start with the open she opened uh because there's more water coming
17:21 Um Then the lake can hold as spilling over whatever the seal is,
17:29 gonna have a relatively stable short. can never fill it over the
17:35 Okay, so it's always gonna be the rim level, it's never gonna
17:39 below. So here is the rim . What they call a spill
17:44 Okay, um inflow and precipitation is greater than outflow and evaporation because the
17:55 is constantly being replenished. We mainly solicited classic settlement derived from the rivers
18:03 erosion of the sides. Okay, again here we've got that zone of
18:11 but now that uh this was eroding depositing, here's our turbid ites,
18:17 our delta's okay. And here's our sedimentation. Now down here, the
18:27 are laminated. The mud are laminated they are below the zone of mixing
18:38 the this particular lake or this type lake is often stratified with the more
18:45 water below not being mixed with the dense water above. Okay,
18:53 right in here we've got homogeneous mud laminated. That's because it's oxygenated is
19:04 above anaerobic below. And so what have been laminated mud has been biology
19:12 aging is more massive. In that's the area where we're gonna get
19:17 related sedimentary structures. Okay, so we have an example of what would
19:29 decreasing brain size towards the myth, that really depends on the Botham itri
19:39 the shape of the source or source of the sources in here. That's
19:45 not the case. So in the geometry, even though open lakes
19:51 to have solicit classic settles, they to find with distance from the
19:58 It doesn't always hold that the finest be in the middle. That's usually
20:04 case, but not always now closed , on the other hand, does
20:09 fill past the spill point, more is leading and it's coming yet it
20:21 fill to that level. So as result there's a lot of up and
20:27 movement depending on climatic changes in the of influence. That means you have
20:36 shorelines as the water moves up and and there's a lot of chemical precipitation
20:45 and carbonates. Okay. And it to be sailing tends to be more
20:50 a salih lake then the open legs tend to be fresh. So here
20:59 got areas that are exposed during low of lake level dry periods, you're
21:09 have a lot of evaporates here, of apple rights and you may have
21:14 nuclear hated evaporates as well. And may have some sediment come celeste classic
21:21 coming in as well. But an lot of it is going to be
21:28 precipitated, dissolve solids. Well, legs are typically associated with internal
21:38 Okay. And if you look at those areas are there Australia, the
21:49 , basically, they tend to be desert areas. Okay. The Gobi
21:58 less so with the pompous sitting But And the reason for that is
22:04 you want to establish a through going , you're gonna have to fill all
22:08 holes. It's kind of a fill spill. The next fill and spill
22:13 and spill. Giovanni reached the Zeke if there's not enough rain. You
22:19 feel that first bill. And so drainages are typically associated with arid
22:27 They're also associated with areas of a amount of block faulting. So the
22:35 way too segment. The Grandage basin to break it up into fault horst
22:46 in fact we saw that with the grande route. Rio grande river was
22:54 the headwaters of the river and the partition by block faulting during basin
23:00 During the Miocene. It wasn't until those robins were filled and spill that
23:06 have the reintegration of the Rio grande . So if you're looking in south
23:12 , um you don't see much until those block faulted bases had filled in
23:21 one of the reasons they filled vaulting and so I couldn't maintain the relief
23:28 eventually the Senate filled it. So eventually do see the influx of sediment
23:33 into Rio grande health after those closed had filled. Now let's go back
23:43 look at stratification for a second. we look at solar radiation, we
23:50 to vote example going into the april summit. If that's very uh 10
23:58 , it's probably, oh, the part of the this is, I'm
24:11 quite sure um is well mixed, means it's warm, but it's uniformly
24:21 to the bottom. Once we get that fixing zone, you see a
24:30 in temperature coincided with a decrease in decrease in thermal solar, But it
24:39 levels out in about 4°C. And the for that is that as ISIS begins
24:47 water is beginning to freeze, it to form linked, solicit silica tetra
24:56 hexagons that have a little more space therefore less density. So the most
25:04 packing of water is occurs not at it freezes, but when it's about
25:10 freeze. And so up until that the silicon tector he drew are getting
25:19 together, more dense and then At 4°C. We have our density max and
25:26 like that problem. Yeah. Now thermal type is a measure of temperature
25:36 with them. We can also talk the picnic client which is a measure
25:42 density variations in depth. If you a fish, you might be more
25:50 in the thermal Kline. But if are hydraulic, they're more interesting than
25:56 , because the low density cap is keeps this floating and therefore these potentially
26:04 from the high density lower zone. unless you've got a way of breaking
26:12 that technically by all of this water gonna stay up here and more specifically
26:21 of this oxygen is gonna stay at . Yes, unless we can break
26:28 up. Break up the stratification, gonna have an an arctic zone down
26:36 . So here we have empty Let me on late. That's a
26:47 Mhm. I tend to think about on that really just a transition.
26:58 here's a thumb applying well, lots of that experience poorly mixed.
27:08 , one of the ways of breaking that Nixon later. He's not waiting
27:16 when you have wind blowing across the of water. If I want that
27:21 be late, it could be a . The water accent piles up.
27:28 it filed up? It forces a . So what we see here is
27:37 being piled up a down welling which turn forces and upward. Now nutrient
27:47 water, nutrient rich because they haven't uh oxidized are coming to the surface
27:56 oxygen rich waters are coming down so can have minimal medicine at least the
28:08 . And this probably holds in oceans well. Now in addition to driving
28:16 , there's a lot of features above things that we get along the margin
28:23 large legs and his legs that have big fetch. Uh that we would
28:28 in any marine setting. We get , we get barrier islands fits programming
28:37 . So there's all sorts of Yeah. Um Here's an example um
28:46 very wrong awake. Oh the other I want to point out remember when
28:59 said there's a down dwelling on the side is being that download can not
29:09 bring oxygen to deeper water, it actually bring settle in the deeper
29:15 So what we get are some of sediment drips. Yeah, bringing creating
29:23 settlement down into the deep part. is not a turbidity current. The
29:29 current here, here we're But here are. Whereas here they are.
29:42 induced. So in a strata pot an idealized lake fill. No change
30:01 the water surface. I mean If it's for getting internet in some
30:15 Oscar pods because an offender. Suddenly could be these sediment drifts that could
30:25 the high protected source above it. go through self the same and this
30:36 predominantly mimics pieces. A lot of we've got this. So we get
30:50 and this could be waving to short could be cooperating dealt well. They're
30:56 currently set if it's not a strategy . I think that is to say
31:06 there is uh mixing for whatever months down here are gonna be
31:17 It's the there will be a sediment as we go upwards. We're gonna
31:27 to see on the why here we , what do you think? Primary
31:46 . Structure five. Hey, this the way is exactly the same thing
31:56 happens in green sex going on a scale. Into a certain different secrets
32:04 . Yeah. And in many cases the electrical picture of the gamma ray
32:26 has to be sensitive to the relative of players and and so we use
32:33 as kind of a third great So when you see this uh rise
32:40 one of the hot uh flood saying that that's a whole another area of
32:52 . Well, log interpretation that I'm know, kind of ignore except for
32:57 I just said. Oops. so we've got the sense of stratified
33:06 non stratified. Now let's look at and let's think about source for specifically
33:20 relative size of the catchment areas compared the size of the face and as
33:31 increase the relative sides of relative, gonna get more more water coming
33:42 So you'd expect perennial place like always be with this large, but you
33:55 also the climate is gonna and does good. So with this climatic
34:07 we basically go from, well dr , large catchment basin turn so larger
34:25 this field here, that's here. you got this perennial link, it's
34:33 open lake. Um but you're gonna you get more and more for any
34:41 uh geometry as you get drier and and ephemeral lakes that eventually gone in
34:57 solitary. So it begins to give a sense of how drainage and lake
35:09 and climate affect the type of length we're getting. So let's take a
35:16 lake that might actually evolving from flood say what are the types of
35:24 Yes, we would expect. alluvial fans are gonna be in all
35:30 the things that we're talking about But then as we come into here
35:36 but flats, maybe a sand dudes, rich and probably error.
35:45 gonna break it. So that might a kind of a typical hold
35:57 All his leg supplier said this is from your textbook, this is more
36:05 the line of what dr Davis might been talking about. But again,
36:12 got this Bahana sand flat with without saline lake and okay, such as
36:29 see their help with the alluvial fans the fan plants to the mudflats and
36:40 so in as preserved, we're gonna this inter bedded kind of muddy flats
36:50 the back lines. That's the first . This is gonna be where we're
36:54 be looking for bad and neither are of the sequences you might get on
37:02 lake margin in early on preserved in deepest parts are gonna be a permanent
37:15 saline waters. Well, now, the water begins to drop as we
37:22 from the open to assistance, we from a perennial to a criminal
37:30 We go into a permanent decisional. . When it was permanent and particularly
37:43 it's stratified, here's our oil change here's our mud stuff. So this
37:50 going to be that base of the and he's gonna be. But on
38:09 no beach, obviously that was big . Got themselves. So you just
38:16 some, we're looking at if that here in the center as well as
38:31 the what one of the things that still grapple with is the fact that
38:41 can get a lot of evaporating deposition the center plate because it's hyper selene
38:50 we're getting crystal growth on the the crystal here or often growing within
39:05 muddy matrix. And so they're gonna logical if it was sometimes called chicken
39:11 structure. So this would be the for permanent non stratified assault. Let's
39:23 an example of where that may have out. This is in Argentina and
39:29 is uh, an oil field in restaurant. It's got the vaulted
39:40 Alluvial fans reading into the company Right here the light, lighter
39:54 lighter color. Come right here, flows. Grady, I'm sorry.
40:03 dairy flows of the orange. These taylor's coats. Whoops. No,
40:17 about? I'll be there. We a tactical for one. Okay.
41:21 need to get back to screen too I can't, I can see
41:37 but I can't, we'll always have . Okay, you're trying. I'm
41:54 need your help again. Sorry, can't get back to this that and
42:17 clicked that but I don't see click different. That's what I want to
42:25 to. I can't forget to here we go. Don't know what
42:45 did that this them stuffed shirt. , okay. Where I want
43:08 Okay, Alright, okay. We're where we were, we got this
43:17 in the no mid to distal alluvial . The fluid. Then we go
43:34 , let's look a little more specifically what's going on. Okay,
43:53 We had periods of relatively low standings brought with a lot of reworking of
44:08 of building. It was eric it a lot of evaporation getting bailey
44:23 strict ID. Like with significant So that was the evaporative period will
44:33 a lot of evaporates forming at the drum, analyze ships in the hairline
44:42 level rose when it got wet. so the lake became less sali less
44:56 and it began to rework those dudes has extensive do feel during the
45:08 No, Those sentiments will be only Dr. seven or positive as high
45:19 flow sedimentary gravity flows down into the water to overfly the embankments. It
45:29 time and time again. The evaporator . No doubt respected writes carbonates
45:54 Uh, so that intermediate zone right here, we lose it when we
46:09 too far away. I protected for lose it over here where we don't
46:21 the map lines. So this fluctuation open and closed or at least more
46:28 . And let's say leave uh, is giving us a significant opportunity for
46:38 pay zones. Now, when I about here is really the classification that
46:49 mainly use or is mainly used most . But let's begin with thinking about
46:57 long and still maybe another. Let's on this. Right, wow.
47:12 into in a series. Oops. , I'm just saying, okay,
47:33 exiting right here and of course it's do that for. So climate tectonics
47:48 determining how much is coming into the basin floor subsidence and still uplift affect
47:56 accommodation range, which is. So look at this. The rate of
48:07 coming in. Both water and sediment is a function. The large extent
48:22 the amount of precipitation. More water blowing into the city for precipitation over
48:34 yet. Oh more water percent. not any subsided what you're gonna get
48:47 . Really? Oh and by the , so the extremes this is
49:03 No matter what the wrote the accommodations it's gonna be old. There's a
49:11 of variation within here but that's the . Uh huh. Here though,
49:18 gonna happen as you increase the ratings science for concentrated water again you're gonna
49:29 from the river related because there's a of waters in these overfilled with his
49:39 over until then. Yeah if you to increase the accommodation brain but you
49:52 change him out with water instead of in. That's gonna become a balanced
50:00 and field. So you can talk being overbuilt. Yeah. Out under
50:18 . Let's see what those look. When you got increase accommodation brand tend
50:40 go from thin sick. So so at this here. Why is it
50:50 is the package here? Let's do here thinner than here because of the
50:59 in a combination left The last 7 10. So I had the thickness
51:13 the custom. Right okay so let's what is it characterizes overfilled with.
51:28 1st 1 overfilled lake is an open . Therefore love to stay stable
51:38 Well in fresh water in the if think of this as being a half
51:53 . We have the master ball over with alluvial fans going into now.
52:04 here we have belters as well but procreating and they may actually be in
52:15 typically hard associated with large. It's to make this connection. Exactly just
52:26 these can be larger like I mean built well and the appropriating as well
52:39 so as a result you tend to from grading para scenes with a lot
52:50 flu bulimic, anybody looked like this . And here's another example of a
53:06 open, right killed it. Now particular of the gods at all.
53:22 a good place to get some of , the petroleum characteristics. I'm just
53:28 kind of skip over it because it's but basically highest porosity and permeability and
53:36 overall resource associate are associated with these . Okay, okay. One of
53:43 word once started teaching some really important realized because I never looked at things
53:55 big plan, the profoundly just needs deeper portion of the thing and that's
54:02 your yet they cannot now balance bill open sometimes for Les, which means
54:22 gonna be variations from periods of time at least on the low relief side
54:30 going to get transgressions and regions we're going to get stable program. So
54:40 gonna have well showing of, we talk more about but basically as the
54:53 fan belts building cycles, input Um they're the best vertical permeability
55:14 But again, I'm gonna leave you look at these as you like.
55:21 field are close links. As a , it can be a lot of
55:35 and blood stones in punctuates a completely . You still have, we still
55:44 some code. Let's make it We might get some travel coming up
55:53 the hot springs, there's gonna be recharge and so we're gonna get a
56:02 of the vaporize and other characteristics. a clothesline. This is our imposing
56:16 it has the thickest death penalty in because approaching vibrates accommodation. Hey shot
56:27 best horizontal when but it's complex you can you can make this situation
56:40 here's an example. 1 2nd. you. Try. This is ray
56:52 . It's never completely inversion but it's fun. We get blood cracks,
56:59 mats information. You're back basically do high percent concentrations. If we look
57:15 this area here standard, just have better idea. Think she's tried of
57:20 of the shallow saline lake systems again the shower. Hey, and you
57:35 be an example under filled lakes. then this is I like this diary
57:47 it kind of give me a visual of thinking about the transition from overfilled
57:56 under filled with really overfilled. You get there should be solicit plastic
58:11 But as we get more into balanced classic sediments begin to drop out.
58:21 begin to take over and then evaporates there. So that rights are dominated
58:29 the under filled and mixed. You flu viel to evaporate rights and
58:38 You get predominantly classic physical sedimentary That would be the uh sedimentary structures
58:47 uh cross bedding. Okay, dominantly began to get biogenic structures associated with
59:00 carbonates and then chemically associated structures chemical with the of athletes stacking goes from
59:12 gradation to aggregation biodiversity high in the . The load of very water low
59:20 you build from freshwater to hyper So it's intuitive, but it's a
59:29 visual way of thinking about what's happening that lake goes from open,
59:35 overfilled two closed hyper saline under Okay, and again, I'll let
59:43 read this, but it's kind of summary of what I just said.
59:50 there's a lot of oil in different environments of the lake system. There's
60:01 lot of it is from streams, streams and greatest streams, alluvial
60:07 van deltas. So we're gonna see and we're gonna pretend like that doesn't
60:12 . Uh We're gonna look at these environments to see what are the reservoir
60:20 . And so one of the things recognizes when we're looking at the evolution
60:24 a base in Philly. Uh We're gonna look just at one type of
60:32 , those legs change with time, like the alluvial fans. We saw
60:37 with time. So it went from ville to overfill the balance to
60:42 And this is just for one of basics. So let's look at some
60:50 the lancastrian systems in terms of tectonic and basis. Or we can look
60:59 the east african rift system, which the way is, is a dead
61:06 for those early drastic to cretaceous rift in north and south America. So
61:16 you're interested in sub salt riffs, the analogy is at least in part
61:30 what is exposed in the northern midland there's no salt like the Newark basin
61:37 also in the east african rift we've got a big sad lake here
61:44 a lot of lakes running down So let's look at a typical lake
61:51 lake structure well and it turns out a series of half problems even though
62:00 think of it as being pulled Extension is not giving us nice,
62:06 roberts is giving us these alternating zones half province. Let's look at it
62:19 closely. There's a half Robin, a half Robin and there's a kind
62:27 a transfer zone connecting those to have in different directions. So we have
62:35 hinged margin and in there's a lot different words for this main fault
62:42 but it's our half brother. Now beginning to see where some of that
62:56 , those deltas come from because there's lot of drainage basin area available to
63:05 into the hinge, March, there's much drainage basin area to go into
63:10 escarpment, March. So that's where would expect your little Fan belt is
63:15 we saw the western side of the of California. Okay, this might
63:24 more like the eastern side of the of California, draining larger areas.
63:31 . Now, if we look at species within this lake, which is
63:42 pair of half Robbins, um one the things, I'll point out here
63:50 then I'll look a little more The second is that we've got deltas
63:59 in here and here. Little Fan aren't bringing much, we've got a
64:06 of classic mud here and then a blanket down here. So there's a
64:16 to sell axle trans gradation, this not mud in the middle and sand
64:23 the sides. In addition the sand the west side on the hinge margin
64:31 much wider than the sand on the or escarpment margin, which is much
64:41 because we've got more drainage area and bigger rivers coming in on the hinge
64:47 side. Now, if you look little more closely now we were looking
64:55 hinge margin over here, not only we getting rivers coming in that are
65:00 large, both axel and on the , but we're getting these sublet custom
65:09 and delta deposits are hyper picked delta . He was here just Fan tells
65:16 not much. Yeah, and this that russell. So the wind is
65:26 from south to north and therefore the deposit before the classic deposits are restricted
65:36 to the northern zone, much to sun. This is a family of
65:48 , the east african rift system that tremendous fluctuations in water level hundreds of
65:57 . So we actually have high low stands deposits. And we even
66:04 what's kind of analogous to a uh, a continental slope. Dark
66:10 shell. Right? And we have size canyons and sublet custom fans.
66:20 . And then up here, I deltas, We have up to 300
66:32 uh lake level base level change. uh, in 12,000 years.
66:42 now let's say, yeah, About years 150 In about a 4000
66:53 That's a lot of change. It's a lot of water that's lost 97%
67:02 in water volume And 89% reduction in surface over 150,000 years. Yeah,
67:13 here's that same module. But this the accommodation. So the rift shoulders
67:19 the block vaulted area. I'm the block fault margin, The flexible
67:26 is the shoulder. So this is half roll and you can see how
67:33 changes as we go down with robert's . And and that's basically what we're
67:44 here. And that's basically what we talking about with the open overfilled versus
67:53 field. Okay, so this is model that we can visualize in cross
68:00 and here's a model, we can for that same half Robin in Matthew
68:08 have the active margin where the main is with a series of small Olivia
68:21 and fan deltas depending on whether or the lake has been filled on the
68:31 side. We've got larger alluvial fans in some cases deltas. And then
68:45 have an axial river that typically is in well parallel to the troll.
68:56 let's look at some examples. Let's first of all in a case where
69:02 the lake hasn't hasn't been filled So here's a case what we got
69:09 symmetrical Robin with Fan deltas coming in into the lake and braid deltas coming
69:19 here again from the lake, it's these have a larger drainage area.
69:24 is that lower areas, it's not steep, still fall boundaries, it
69:31 out, but it's not as And then we have some deeper water
69:36 going on here. Sobre deltas where less subsides. Fan deltas where it's
69:42 and smaller granny jerry here we have deltas, we have the main fault
69:52 rather fans. They were fan deltas just one leg compared to more stream
70:02 deltas, larger and more water related there's a larger drainage area.
70:11 it's a half dealt. Yes. you can see the difference in the
70:19 area and therefore the difference in the of the alluvial fans and the difference
70:28 the type of sediment transport larger drainage . Higher, more precipitation. more
70:36 related stream flood stream, um, relief a small area. Your brain
70:43 . Okay. Uh, here's a where we've got an axle river coming
70:49 forming a rather large delta that's filling this lake. That would be analogous
70:55 this longitudinal river. Here here we the river building in the fault bounded
71:10 alluvial fans, merging with this longitudinal and this was a lake until it
71:26 up the same pattern. And one the nicest examples is a devonian and
71:36 shows that trans intentional half throttle Up 25,000 ft of cm of set a
71:47 of subsidence and on the flanks on flank, we have stream flow dominated
71:55 and another flank other side. We the brief flow dominated fans. And
72:03 you look at the math view, got debris flow plans, larger stream
72:12 plans in an axial delta coming filling the lake in particular cross
72:22 We have these smaller, smaller debris fans in these larger streams of
72:31 Again, we're looking at them here then what this is this is the
72:39 filling up with this actual river actually a graded stream. Okay,
72:46 here's that like custom fan delta, coming down the axis and here are
72:54 little fan deltas coming in from the . Mhm. And we talked about
73:02 before. Van delta, braid Ban delta, braid delta, Van
73:13 , Xray delta. Here we go , steep, steep here. We
73:24 have a distributive alluvial system. It's a large system that we're actually getting
73:30 splitting up. But again, the of these asymmetrical robins ban raid or
73:52 , 3 15. Uh you wanna now or try to finish up and
73:58 it over. Hey, okay, . Well it'd be nice if we
74:06 just finish it and leave early. . Um, Gilbert type deltas are
74:13 assumed to be the norm for the deltas and the Gilbert type delta is
74:20 described as one that's got Top steep four sets, shallow bottom
74:30 just like this. And the reason the, or the assumption that these
74:40 what should form in deltas is because you have fresh water, alluvial deposits
74:52 and diverging into a fresh water you have what's called home a pick
74:58 floor. The density of the in water is the same relatively as the
75:08 water. Fresh water. Fresh So the argument is, you have
75:14 very rapid divergence. The flow lines rapid sedimentation rate and the deposition of
75:27 four cents might look like this. , and this is an example of
75:37 Gilbert type guilt. The problem is in a marine environment. So the
75:45 thing we have to acknowledge is that type deltas can occur in marine as
75:54 as the acoustic settings. They're not to the customer and they're not unique
76:02 or float. um that are well , very steep. A lot of
76:11 sands, massive gravels, a lot sedimentary uh defamation. Here's another case
76:20 marine deltas. Starting off is what shallow water deltas and gradually as the
76:33 deepens grading into Gilbert type deltas. what what Gilbert type delta is really
76:44 are delta's pro grading into deep relatively deep water without a lot of
76:54 . So you're depositing large force. into that system. It has almost
77:04 to do with the home a pick flow. And it's not at all
77:11 to lakes. In fact, many deltas are completely unrelated to Gilbert
77:21 Now I'm expanding on this because we read everywhere. This is the type
77:27 delta you get with lakes. it's the type of delta that you
77:31 in alluvial lakes that G. Gilbert described around Salt Lake City when
77:41 lake level was high and it was into a steep front. Yeah,
77:52 do see in this case it's lacosta Gilbert type deltas, um pulses of
78:01 grading transgression for grading transgression. In particular case, we're looking at sequences
78:12 to episodic thrusting. We talked earlier how alluvial fans. Systems could pro
78:20 and out by thrusting by tectonic lee allergenic site, they're all asleep.
78:28 , so this is one case um lake bonneville, it turns out where
78:35 Gilbert deltas were first discovered and they basically, the course reigned steep
78:47 Water deltas elsewhere. We got fine deltas that weren't Gilbert type. So
78:55 have taken these three or four examples it is multiplied like mushrooms.
79:04 Now the rest of what I'm going talk about, our case studies,
79:10 of chinese deltas. And then reservoir associate with those and I'm gonna talk
79:16 the Bohai basin, the Hunger The early in basin doesn't matter their
79:22 necessarily, but know that you can them if you wanted to. And
79:27 look at the early in basin first all, and this is a really
79:31 early publication by chang song Back 20 ago. And if you look at
79:39 cross sections, you see there are bunch of mainly half problems. This
79:44 typical of the structural setting of these bases. Okay, have problems.
79:52 so here's a a and interpreted seismic . We had alluvial fans raiding into
80:03 deltas. So we've got lake Now, then down here we're getting
80:10 lancastrian deltas are fans wrapped over here deltas. So we're seeing this transition
80:17 fan deltas on the steep flank to deltas on the less steep flank.
80:25 , if you look at the deposition within the early basis, the size
80:31 , field grade deltas and the Subway fans and hyper pectoral deposits here are
80:38 main residence, Louisville fans. Don't about. We've talked about those and
80:44 not reservoir, but they're restricted to early phases of that delta before it
80:53 a lake. And actually maybe at , the later phase where the lake
81:02 filled, that we would have alluvial bands grading into non lancastrian lake
81:13 . Fan deltas are occurring when those fans are now grading into a
81:20 The system is closed or at least the accommodation rate has increased. But
81:28 getting a lake water. We have delta front and then a floodplain.
81:41 delta front is where there's a lot reworking and therefore it has. The
81:48 for being a resident is that we something in here. It's also that
82:01 and we saw in the devonian where were looking at that axial lake coming
82:09 axial river, rather filling the lake the east. Now, here's what's
82:18 a fan delta for the hunger. , I'm not sure that it might
82:24 better called a braid delta. There's its transition. But this is a
82:30 fact. These are, these are and inter channel bars. Uh,
82:36 is a reminder that you will be an error if you just do a
82:42 strata, graphic correlation of sand You need to do a chrono
82:47 graphic correlation. Uh, here's another where this sand does not correlate with
82:55 one. Correlates down here. So have to think about what are the
83:02 that are giving you the the The pro grading timelines and therefore pro
83:12 sands. Anyway, so here are deltas and the reservoirs are mainly in
83:23 zone here in the fan delta That's the reworked area. Yeah.
83:29 those are gas reservoirs here. We've a fault here. Van Delta's here
83:39 great Delta's here raiding into a delta . There was a lake there
83:49 We've got Van Delta's adjacent to the margin, gray deltas to the southern
83:55 . Okay, that's what we're looking here in a different reservoir, except
84:02 , we're actually looking at the we see this pattern over and over
84:09 , the great deltas or some of better reservoir. Some of our best
84:13 were their finer grained, they're thick coarsening sequences probably when it was a
84:23 delta. This is an example of variation and permeability in ferocity of one
84:35 those delta lobes. So there's a of variation in here, which we
84:41 talk about later. Talk about deltas here we have not a great delta
84:49 a meandering flu viel delta. Uh again, both our river dominated
84:56 And so these would be the equivalent those stream flow to unconfined or two
85:10 river belters. Okay, and they're occur in the axis of the trough
85:18 on the lower gradient margin, non margin of the half Robbins.
85:25 eventually those fan deltas and those meandering great deltas coming in are going to
85:31 the lake. Okay, so the is gonna disappear. And what happens
85:38 this? It's all meandering river and fan. Yeah, we can have
85:49 stand and low stand deltas that can opened and closed, insane vertical
85:59 I stands tend to be wave Remember how much area was covered,
86:08 , uh to wind on the high of the lake Malawi. More
86:18 more of a wave dominated delta down , there's not much wave actions.
86:24 little more flu ville dominated. You have a lot of evaporates if you
86:30 to know where the best reservoirs Look for distributor very channels and mouth
86:38 in those delta and lacosta and delta . Okay, we'll skip that.
86:46 , another good place to look is incised valley field. Here's that incised
86:52 . Okay. And there were getting pretty well sorted, forced to find
86:58 stones and gravels. Now, what's these they're gonna be submarine sedimentary gravity
87:08 and slopes. Here's a cohesive debris . Here's a high density turban tight
87:19 here are thin bedded, lower density . Now there's we're gonna spend a
87:28 of time talking about these types of sedimentary gravity flows. We talked about
87:36 water, marine setups. Let me say here that we get the same
87:42 of sedimentary deposits in lakes as well the marine and dark. And we
87:50 the same transition from Deb writes the pick nights which are hyper picnic flows
87:56 I will find that a little better hide to low density turbo tights.
88:03 , so here are sandy debris flows muddy debris flow and here's a high
88:15 her body, the low density turbodyne this particular turbid Aight is serge like
88:28 this particularly turbid ite is classy Now, what we mean by that
88:35 search type turbo died is one that there's failure very instantly we get all
88:43 sediment put into suspension in one event then it spills out into the deep
88:50 of the base across a stable low interpreter is one that's being fed over
88:57 long period of time and that's due a river. I concentrated river sediments
89:03 into a basin for a long That's what I mean, a long
89:07 . We can have rivers in flood weeks, maybe months, but certainly
89:13 . And so that's gonna give us different pattern of deposits. Now,
89:23 actually showed this earlier and I said was an example of a relatively stable
89:30 grading para seats, but in it's not stable. It's kind of
89:37 up up. So there's a pro , all climate forms followed by an
89:46 platforms and procreation. Now, that to do with the rate of sediment
89:54 accumulation. That's pretty straightforward. But importantly, okay, when it's pro
90:02 , these deltas are right at the edge and they're slumping. And these
90:09 are giving you a series of slump and deeper fans when it's more
90:21 These are beginning to break into turbo channels in submarine fans. So we
90:32 bypassing the deltas to get into the water deposits with sand. Now,
90:45 the slumps, this is kind of we get this slump induced fan and
90:54 often elongated debris flows. Kind of like those debris flow lobes. We
91:02 on that debris flow dominated, uh fan. Now, they're associated with
91:11 steeper front here. This is an a pack, but it really consists
91:17 a series of overlapping lobes. and you can see in cross
91:29 this is one in brazil. There's delta, here's those individual sand lobes
91:40 grains uh too 30 m, 30 thick sandy loads got a potential
91:55 Here's another. Okay, um up 60 meetings of Sandy Lopes here are
92:07 of the slope deposits raiding into turbidity . Okay, in fact, that's
92:18 of what we're getting here as we from a sandy debris flow to muddy
92:23 flow to turbidity currents. Now, it's slumped, it's gonna be a
92:30 single event turbidity current. Okay, here are those Sandy Debra. It's
92:37 are permeability is up to um it millie darcy's uh yeah, or
92:46 it's not millie darcy darcy permeability is to 8 to 14%. I gotta
92:53 this, but permeability is high enough these are residents. When we look
93:00 in here, Here's permeability, ease up to two Darcy's averaged 200 million
93:09 for these sub custom fans associated with Debra writes here. Lower uh army
93:22 . Similar the lower process. I to double check this out here.
93:29 , here's a blood triggered system slump system, debris flow, high density
93:39 . Current policy, steady turbidity, debris flow. Oops. To search
93:47 density surge like turbidity current. The thing I want you to remember for
93:53 now is that these deposits can be our bridge and uh and laterally
94:06 But they vary let because what has is very deceptive. There is a
94:15 of that sedimentary gravity. Yeah. I did see tremendous crime today.
94:33 . Oh yes. Each of these have a characteristic sediment package.
94:45 I'm gonna defer talking about what those are and therefore how you distinguish.
94:52 I want you to recognize that there seven biological signatures for each of those
94:59 , even of a single event. can think of this almost as a
95:02 . She's man um of an So here we have coming in in
95:12 water and here we have flood generated to diets and there we have paint
95:27 generated turbo adults. Yeah. Here the slump generated uh sedimentary gravity flows
95:39 you mainly Sandy device. And here the flood triggered sedimentary gravity fluids.
95:47 um Well fine. Now these hybrid are basically flood generated, 70 friends
96:09 form in you can have this So coming in and they're staying high
96:21 a long period of time. So is basically the duration for yeah take
96:31 focus and as a result you've got and and erosion at various times as
96:43 information that material is accumulating. So got a variety of vertical sequences.
96:54 you don't have is that plastic bomb sequence that we think of turbulence finding
97:04 massive parallel Ripley. And again um it's that vertical variability that is characteristic
97:17 I predict whether it's or something or . Custom, vertical, very building
97:24 size, anti sedimentary structure and thinks can be a lot thicker and many
97:31 they are more long lived. Um Here's just an example of some
97:37 the variation you might get. Uh player later. Um here we have
97:54 upwards the packets but at different scales have the this variability. Yeah.
98:08 similar story here. The take home the variation and the origin here,
98:21 not a hypertechnical, it's a failure time we generate a degree flow going
98:32 . But the density of the turbidity is getting less and less in part
98:37 it's incorporating water as it flows down because it's a signal and then we
98:45 the capacity development finding those same very . Get um getting towards the end
98:58 . Uh This is the north Auckland in the south atlantic isn't that Robin
99:08 is uh, this if we look that as a half problem, what
99:20 we see side? You see little and a lot of these subs custom
99:32 . These are the major residents and inside sally. These are just kind
99:45 some sketches and some of the vertical here are those fans that's time slice
99:55 they have broken up in folks if this looks very similar to when we
100:03 in marine. There's a lot of and basically what type uh det
100:23 These are the, so when we're into the deeper water causes, we've
100:35 two things either have sand coming My slumps and surge is one or
100:44 setting out of suspension. So the consists of fine grained material. I
100:54 much in some cases the uh, it's shallow it may be blood
101:06 stones will bring money, but below critical death using we get the six
101:18 that are typically laminated, high organic . Um, Nick writes so and
101:32 missing. Well clued you an, ignoring all of those sand um,
101:40 gravel tons. This is what surrounded forces your brain deposits. And one
101:48 the things we recognize the country particularly those portions of them that are
101:54 in an anoxic conditions is they are laminate. Mm If you look at
102:03 lamination, they are typically, let's often patient place Number one, you're
102:14 there. The annual barbs that we of the blood customers deposits. Now
102:21 other ways of getting lamination. Um not gonna get into as much as
102:27 the text. You can look at later, you can peruse and but
102:36 vary from where there's something controlling them a kind of a regular basis like
102:45 , weather conditions to irregular events, a volcanic talk or something else.
102:53 , when you look at those look at those deep places, fish
103:05 began to look at herself. We one of 48 analysis that if you
103:13 the east lamination is a year, is pretty good. It's then you
103:21 figure out that you have certain peaks varied a certain find italy. There's
103:29 20 years. So. Oh I mean 20,000 a. 40,000 140
103:45 . Those are basically climatically controlled. , have you heard of like
103:56 Okay, okay. A cycle is a cycle of variations in incoming solar
104:08 based on long term astronomical changes in position of the earth and sun.
104:17 so uh an 18 year cycle is common. We can see that in
104:23 title process. But the 120 year is the cycle that seems to to
104:31 glacial integration. And we have finer and longer cycles. So a lot
104:39 our twice the scene climatic variation is by along these cycles. And a
104:47 of the cyclist city in our sedimentary is driven by that as well.
104:56 , we had these red lights down very small. Here they are,
105:06 getting larger and larger cycle that basically annual, longer term dynamic cycles in
105:18 cycles. Our technology. So we a combination of tectonic automatic control on
105:30 cyclist city, both the alluvial fans customers policies. Let's try that.
105:40 this is one. So this is this. It's And we're looking at
105:55 delta. All of your fans. . Bringing up into um public
106:08 fans ready back in. So a Mhm. And a cross section that
106:27 like this. Here's a great diligence the way, you know, lower
106:39 relief, lower rates of subsided that a problem. Here's our against the
106:59 we got shallow water deposits here overline flu beginning of the plan to transition
107:08 shallow delta. And they're going to water. We begin to see the
107:20 things is greater than the settlement supplies paper people beginning having great. This
107:32 more of a um overfilled setting. in notice we've got these deeper water
107:43 packets that are the simpler custard fans summit size balance. We can also
107:55 of axial center sources coming in here's our it's like and that's pretty
108:13 . Uh You won't say it but state we're beginning to say that
108:21 in in the chinese uh Custom systems least all over china. And actually
108:29 different tectonic settings? We're getting similar of the customer based film? Here's
108:39 one that's predominantly shallow to the function . So it's more of a balance
108:47 close this balance of 100. But ray delta shell. So what we
109:03 way we had this vertical transition from D. So here is that cross
109:20 be shallow. So this is how cross section might look a delta.
109:37 when we look at this, that's of what we're beginning to see.
109:49 this is a model that suggest that a half problem. And as early
110:01 it's a shadow room filled. That accommodation space increasing. Now that's filling
110:19 , delayed is actually even filled. still we have a border fall that's
110:26 the center. At some point we post riff for the sediment expands over
110:32 while. In other words, the have subsided by thermal subsidence and erosion
110:42 then there's no more base and Okay. And uh that's sometimes called
110:52 the longhorn model because it's got Okay. But we see it.
111:03 I mean that's typical. And so is just kind of a discussion of
111:08 style and the problem with this cross is something missing. What is missing
111:23 this graph section that I've shown you Many other cross sections. There's a
111:37 deposition system or systems that aren't shown . What are they? We got
111:52 like delta food. Mhm. Is nothing else that we talked about particularly
112:03 the margins with the face. She's at times too. The please tell
112:24 no thank you. So if not is missing in that space, she's
112:33 that just kind of describe crossing from in custody. What? I'm
112:52 Yeah, challenge. But there are shells. So the first thing is
113:05 is all the sudden stuff. The absolutely. We would expect to see
113:15 stand bodies in here. Now you argue maybe scale, but what's
113:25 All businesses, all the alluvial all the fan belt that are coming
113:33 from the flat. This delta here maybe coming from the actual plane where
113:47 filling up the whole valley. But was, and also it shows
114:01 I want to make this stops right . So, uh, this is
114:14 just here, it doesn't show the , but here's the filling. Remember
114:22 we had the, those axle deltas side delta is just completely filling the
114:34 . So I'm gonna take it. , I'm gonna have a question on
114:39 exam, we're read something like draw a cross section of a half Robin
114:56 you go from early flu viel through custom to a real system including syn
115:09 and post rift geologist. Okay, that's gonna be kind of a
115:15 this diagram, this diagram, that plus maybe some details. So you
115:24 to think about that first of And then I'm gonna also ask you
115:27 also draw the face. She's tracked a typical half Robin where there is
115:42 significant portion of it still having a . Okay. So you might think
115:49 it as someplace along will someplace along . Yes, or along here draw
116:04 the map view of the deposition system there we go. He got a
116:10 of sitting there. They don't get . Okay, so work with
116:18 And the last thing I would just that you know these these changes from
116:23 , maybe deep to shallow alluvial um They reflect in part long term
116:31 in the rate of sub science. the deep lakes typically are where the
116:38 rages uh the greatest and and as turns out um there for example
116:49 Alright, the but it turns out you're looking for source law, they
117:02 with those periods of baptist sons. bars are actually subsides rates. So
117:15 wider that bar the greater the substantially intervals of source rock formation are shown
117:37 . Okay, those deep lakes, source rocks are being to us and
117:48 in addition uh they are probably the where we have the longest lived and
117:58 and toxic deposits, the dark shapes ships. Yeah. So in
118:10 this is a good article to read the customer unconventional resources, no permeability
118:19 probably horizontal drilling or fracking. Uh gonna let you read this, but
118:29 of the things to point out is the custom deposits can be quite deep
118:40 of Lake Malawi 6000 ft of Uh, and again, you can
118:51 this. Okay, this lower Permian here. This is a good summary
119:02 why this particular lake system, as hydrocarbon potential. And this last
119:11 is to remind you that those deep rich, the customer deposits have to
119:27 expelled and then you have to get to a sandy reservoir. So they're
119:32 be mainly coming up false. So gonna come up the fault and then
119:38 distributed in this area here. you're looking at the migration as well
119:43 the source of industrial ones. All right. Uh, that's all
119:50 can talk about because I'm talked So I'm going to I suggest we
119:58 reporting better than
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