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GEOL6380 Sequence Stratigraphy - Day5 05-06-2022
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00:04 get started. Sorry. So I all the lectures up. I'm guessing
00:16 probably downloaded the PDFs and can follow . So going to start with some
00:30 deconstruction, I call it. Uh we're gonna talk about the sequence photography
00:37 alluvial systems sort of with some general , some of this would be a
00:41 of repeat from, from our early . So I'll review that stuff very
00:47 . Mhm. But let's start with diagram. So this is a diagram
01:02 Peter friend was a was the sediment at Cambridge University back in the 60s
01:09 70s I guess. And this is sort of a general diagram. It's
01:15 kind of diagram that I learned when was an undergraduate and even a graduate
01:21 . And what it shows is a diagram. And on the surface you've
01:26 different types of streams. So you've a strongly meandering stream on the
01:31 you've got alluvial fans on the left a. And then be you've got
01:35 streams and see you've got a lot curiosity stream. And if you focus
01:40 block diagram, B and D. implication is that if you have braided
01:49 , you produce big buckets of whereas if you have a strong and
01:55 stream, you produce buckets of mud ribbons of sand. Okay, so
02:00 idea behind this diagram is that the thing you need to know to predict
02:04 large scale strategic graffiti flew real systems the planned form of the river.
02:09 assumption is that the platform of the particularly braided versus meandering controls whether or
02:15 you've got a mug dominated political system a sand and gravel dominated political
02:23 Now, here's a rather different diagram a book actually on braided rivers,
02:28 this is a general diagram that shows stacking of channel belts, those the
02:35 things. Okay. And everything that's in the box, we would assume
02:40 mud. Okay. And from left right, it's got low channel migration
02:49 the left and high channel migration on right. What's channel migration? What
02:55 mean by channel migration? Yes, money. Yeah, that's always right
03:11 say it. Right. And so I'm if this is my hand,
03:17 your hands like this and show me river that's that's migrating a lot.
03:24 are you going to do? and not migrating at all?
03:30 So the more that migrates the white the sand body. Very simple
03:34 Right now in the front we've got revulsion and then in the back of
03:41 mother we have high revulsion revulsion. , that's not the sinuous city.
03:53 what what does the word of vulture ? You know? So avulsion refers
04:06 a river switching its position. So once again, let's put our
04:09 here now a vulture position. And it again, I've also again,
04:18 , now migrate and then a pulse then of course. Right.
04:27 so when you have also the river put the river in a different position
04:32 the floodplain. Okay? And if river switches position upstream, it can
04:37 up in a very different position We call that regional adoption.
04:42 Sometimes a river can adults out of course and rejoin. That's sometimes called
04:46 local avulsion. And sometimes in a of all, she can occur all
04:52 one and sometimes it can occur at points upstream and downstream. If it's
04:58 at one point we call it, call that node revulsion. And
05:06 you know, if the rivers here then it switches that position and then
05:10 switches to that position, that would at a nodal avulsion. Okay.
05:18 from that point, a river flowed and then it switched to that position
05:25 then it switched to this position. . Uh that would be uh random
05:32 in words that the vultures occurring at points on the river. And if
05:36 river is flowing in this position and it switch flips, flips out and
05:42 back to where it used to We would call that a local avulsion
05:49 out comes back now and then on on the vertical axis we've got
06:04 Okay, if you don't like the aggravation, just the word subsidence in
06:08 and whatever is causing the flood plain to build up. Right? Usually
06:12 if the basement is falling then the will build up. If the base
06:16 stable, there will be no Right, okay. so now we've
06:21 three parameters. Okay, the degree which the basin is siding, which
06:26 the aggregation of the floodplain degradation is partly controlled by settlement supply. We've
06:33 the rate at which the channel is and we've got the frequency in which
06:37 avulsion, avulsion. Okay, so look at a scenario in the
06:46 That's weird. That's better. Some I penn was going all over the
07:16 , so let's look at the front . Okay, so now we've got
07:21 basin that's that's maybe subsided quite but the river is neither migrating nor
07:28 in that case, the river just verdict. Now that's not a that's
07:32 a that's not particularly common scenario, that's what you would expect.
07:37 In contrast in the right hair, base is still subsiding rapidly.
07:42 the channel is involved in very but it's migrating along. So you've
07:46 a river that's migrating on a base falling, you get a nice big
07:51 cluster of channel belts. Okay, look over here, we have the
07:58 where the rivers exulting frequently and it's rapidly, so it's producing wide channel
08:04 , but because it's evolving all the and the floodplain is signing the river
08:09 over here when it comes back to it used to be floodplain is accumulated
08:14 . So now you get a bunch isolated wide uh channel belts with a
08:19 of floodplains. Okay, um who like to tell me which of these
08:27 produces the most amalgamated continuous reservoir, scenario would be the best and
08:41 Right. Mhm. Yeah. So least number of compartments and the
08:50 the biggest stack of amalgamated channel belts stuck together. For more information.
09:03 . So that would be this Yeah, Okay, and Maybe that
09:13 there, maybe not much, you , a lot of migration, you're
09:18 a nice big wide chat about, know, and the basic subsiding is
09:22 get a big blob of amalgamated right? Which would be the worst
09:28 , which would be the worst do you think you're drilling?
09:31 you find oil in the sandstone and go like, oh my God,
09:35 100 sand stones, and they're all by shales. Yeah, high frequency
09:44 bullshit. Right, I 5%. much? Exactly? Right.
09:53 Okay. Okay, so we've so what you can see is we've
09:58 we've now this diagram, we have probable net to gross net to
10:03 I just mean that sand to gross . Right? So, essentially,
10:06 share ratio, right? You this would be a lot of,
10:11 lot of sand, sorry, a of mud with a few sands,
10:14 would be mostly sand and very little , Right? Um And what words
10:20 on this slide, What words are on the slide that we usually use
10:25 describe rivers, we go back to slide, nana is not here.
10:32 else is missing graded, right? the two words that we've always thought
10:37 as the most important to describe rivers missing on this diagram. We got
10:43 ah now you guys would probably taught little bit more advanced rivers than your
10:49 were. But to this day I to oil companies and I hear geologist
10:53 about, well, this is a , extremely me an extreme what they
10:56 mean is this, is this a net ecosystem amalgamated? Isn't loan it
11:00 growth? And their assumption is that controlled by the plan view,
11:04 the stream. And yet now we're , no, it's controlled by the
11:09 rate, it's controlled by the avulsion , it's controlled by the subsidence
11:14 Okay, now then you can go , okay, well that's great.
11:18 controls the vault the avulsion frequency? might control that? Okay, what
11:30 ? So the greater the floodplain might that. What else might control
11:35 Yeah, but the number of flooding , ah The sinuous city might control
11:41 if you have a single threat, stream, you know? And the
11:45 is going around the corner, it blow out as a crevasse splay and
11:51 might just, it just might, might just produce an oxbow lake or
11:54 produce an avulsion, right? To braided streams don't necessarily have those big
12:00 loops. So it's possible that that streams don't impulse as frequently as meandering
12:08 , you know what one of the research topics influential systems is right
12:14 that's true. Ah, I wouldn't that. And I'm leading you
12:21 we've just identified a big problem. . What do you think? What
12:26 you think people are trying to understand how rivers behave? Oh, that's
12:37 of interest. Yeah, it's right the slide here. Exactly, right
12:48 an avulsion, right? Everyone's trying figure out what controls revulsion.
12:54 What's, what's the importance of flood versus slope changes versus, you
13:00 details the floodplain, whether it's muddy sandy. Now, it's possible that
13:07 so McDonough's what controls whether a river braided and meandering the gradient and the
13:16 . Right? So, and gradient discharge may control things like sediment supply
13:23 avulsion frequency. So, you there there may be some link between
13:28 plan view of the river and its , but it's certainly not as simple
13:33 these models would suggest. Okay, , so part of the setup and
13:38 river systems, you know, and is a bit more, I
13:41 it's photography, but it's also just physics of how rivers behave.
13:52 we talked quite a bit about equilibrium in our first meeting. And we
13:58 out that rivers will commonly have a area and then that will become
14:04 they go towards the shore line and not uncommon that because asthma Dennis correctly
14:10 out steep graded rivers tend to be and, and lower graded rivers tend
14:15 be meandering. However, when you tribute of systems, in other
14:21 when you, when you're in a gradient part of the system commonly you're
14:24 water and then you go to until get to the trunk stream, which
14:29 higher discharge, the tributaries of the stream discharges the water right? Qw
14:43 , you're the tributaries are collecting water feeding into a big trunk stream,
14:47 which has the higher discharge the tributaries the trump street? Of course the
14:53 street, right? And then it distributive. And so you get smaller
14:57 and big channel, smaller channels. . And so and of course if
15:02 trunk seems big enough, but the discharge may keep it braided even though
15:06 gradient slope. Right? Anyway, we talked about these equilibrium profiles.
15:14 today we're sort of focused on the river profile and you know, that
15:18 drop down if if mountains are being or it can lift off if mountains
15:23 uplifting. And of course sometimes this uh can be connected to the continental
15:31 and of course if that gets you get a steeper slope that's a
15:37 point and uh that can cause the to speed up. And then we
15:44 talk about a bit about choke points nick points. Um This would be
15:49 good point for you to look at . You know, when I show
15:52 diagram twice in a class, you , it's important, right? If
15:57 important, it could be something that might find on an exam tomorrow or
16:02 next week. Right? So this of choke points and nick point is
16:07 , but because it controls where rivers size and where deposition occurs, so
16:13 tends to occur associated with nick a deposition tends to occur with choke
16:20 . Now, we also talked about idea that that there is a window
16:27 zone in which rivers are either either up or dropping down. John Holbrook's
16:33 that the preservation space and and that that that is constantly moving depending on
16:40 river has more water, less more sediment, less less sediment and
16:44 or not the land is lifting up dropping down okay. And he also
16:49 out that that that the president preservation can shift seaward if a delta,
16:54 grades or sea level drops or sea rises, it can change the point
16:58 which the river is granted to. . And so the green, the
17:04 zones on this diagram represent the new space as a buttress shift seaward like
17:10 would occur if there was a regression the shore line or if there was
17:15 gradation of the delta such that the was now flowing over a longer
17:20 Okay. And obviously we've talked about you have rise of sea level then
17:28 the rivers will lift up and they they moved they actually move may move
17:32 if sediment supply is insufficient to keep and of course if there's a cultural
17:36 fall, river's can degrade. Mhm. So mike bloom sort of
17:47 out that most of this is very here, but he points out that
17:50 continental shelf for the most part is at low stands, rivers run across
17:57 and flooded a high status. So when you've got glacial maxima, the
18:01 continental shelves are surface over which rivers flowing. Okay. And so he
18:07 out that most shelves, the grading actually the old long profile of the
18:15 . Now, when sea level Okay, you'll get a new coastal
18:20 . Okay. And the online limit the new pro coastal prison, which
18:24 this green, yellow and gray wedge . Okay. That that Okay,
18:31 upstream downstream length of that wedge is to be related to the magnitude of
18:35 level rise and the slope over which occurs. Right, So a small
18:39 of sea level rise just haven't got much distance to get a new alluvial
18:44 , but you've got a big sea rise and a very low radio claim
18:48 that wedge can jump hundreds of kilometers and it can get bigger and
18:53 The lower the great Okay, all , now we like to talk a
19:05 about boundaries and obviously, you a critical boundary is the shore line
19:12 separates land from sea, but in of shallow marine or Deltek systems,
19:20 you'll have, you know, the river and that may or may not
19:22 incised. And the point at which river is no longer confined, it
19:28 start to pulse. Okay. and in addition to a pulsing,
19:34 may get more than one channel active one time downstream. And those become
19:38 we call, distribute terry channels. there's some question of big deltas as
19:42 whether the Nile has two big distributor and some people say, well actually
19:47 river's just hasn't quite decided whether it to be the Rosetta or the Damietta
19:52 . Right. Uh Some rivers have of multi simultaneous distributor t channels.
19:58 deltas have a few at any So we we we subdivide the delta
20:05 into an upper delta plane, which an entirely alluvial environment and a lower
20:11 plane, which is the marine influence of the system. Okay. The
20:16 between the upper and lower delta plane called the bay line and it's given
20:20 name because it marks the language limit brackish or brackish water bays essentially marks
20:26 language limit of saltwater incursion. of course the custom deltas don't have
20:33 salt water. So there's no such as a no salt water and no
20:38 . So the customer, the customer don't have a baseline uh seaward of
20:46 shore line, you get an offshore called that the delta front and then
20:50 pro delta. Okay, so one the questions is, you know,
20:55 kind of faces changes do you get a result of these moving boundaries?
20:59 baseline is may not be the most boundaries. You know, we tend
21:04 think of the shorelines the most important , but you can get a lot
21:07 sand seaward, the shorelines. So terms of reservoir, you know,
21:10 lots of potential for sand seaward of shore line because the shore face is
21:16 is below is below the shore Right? That's the offshore area that's
21:21 agitated by waves, produces nice sandy . Okay, now the bay line
21:27 the area where tides can influence Okay, the tide goes in,
21:33 stops deposits, a layer of the tide goes out, deposit,
21:38 stops, deposits, a layer of , the tide moves in, moves
21:42 more sand stops and deposits a layer clay. And this happens every
21:46 sometimes twice a day. So tidal tend to have little clay drapes all
21:51 time. And that makes very hetero reservoirs. Right? So title systems
21:56 particularly interest to oil companies because they be complicated to get the oil out
22:01 because it's clear everywhere, Right? because the high because of the high
22:05 to tide, you can have very clean sand in between. So the
22:09 that that that Baylon is of interest that can define the point at which
22:13 get a lot of clay drapes in in your poor alec reservoirs.
22:20 So here's an example of the po in Italy. And you can see
22:26 is a distributor rechannel here, there a distributor very channel here. There's
22:34 there, another one there, there's one coming off here and you can
22:40 these plumes of sediment that marked the terminal ends of the distributor distributor
22:46 So this is where the the distributors spewing their sediment into the sea.
22:51 a wave rework delta. And you see that there are these these lagoons
22:56 in these bays bounded by spits and can see a difference in the color
23:01 well. That probably indicates saltwater tolerant . And so the green line in
23:07 delta marks the baseline. Okay, , tidal effects can propagate if a
23:17 is flowing downstream. Okay, remember talked about the the uh my brain's
23:26 dead. The back wall, we about the backwater. Don't remember what
23:33 backwater is, Right, So it's depth of river divided by the
23:43 Okay. Um Yeah, so in Mississippi would be let's say 50 m
24:00 divided by point zero zero zero So that's going to be 123,
24:14 or five. Yeah, Is that ? So it's going to be
24:34 should be about 500 to 1000 Okay, Now the baseline is the
24:40 range divided by the slope. So the Gulf of Mexico, the tidal
24:44 is about 1.5 m. And so means tidal effects can propagate 30 km
24:49 the river. That's obviously much less the backwater effect. Okay, but
24:55 you've got a small river and high range, then sometimes the the bay
25:00 could be bigger than the back Right? So that's of interest.
25:05 is the Indus Delta. Two images the, in the photograph on the
25:10 , you can see that the darker represents the salt tolerant mangroves and the
25:16 green represents freshwater plants in this. the satellite image, you can see
25:22 extensive wetland and you see all these features. Those are tidal channels.
25:27 you'll see that they look like you've a big channel at the, at
25:31 seaward end and it breaks up into whole bunch of channels at the land
25:34 end and that's the type of water in and breaking up into a series
25:38 tidal channels. And you've got to at this carefully. This is the
25:44 channel that's linked to the river. , all these other channels are tidal
25:51 and have nothing to do with the at all. Now we talked about
25:57 backwater. So, okay, there's Mississippi Uh 40 m divided by .00005
26:04 800 km. The Rhine is still pretty big river. Uh the slope
26:10 quite a bit lower. So it's a backwater of 100 and 20 kilometers
26:15 the backwaters. The point at which river, the base of the
26:19 sorry, the backwaters, the point which the base of the river is
26:21 sea level. So if you've got level rises and falls or you
26:27 or even tidal effects, that's going affect the river up to the
26:34 And uh and that, that has big control on things like migration and
26:42 . Okay. Which I'll show you just a second. So we showed
26:48 diagram before. So we've got the would limit of saltwater. That's
26:53 that's the bay line. Tidal effects propagate further up depending on the scale
26:59 the tides. And of course the effect, as I said, is
27:03 water depth of flow depth of river by the slope and that may be
27:10 than the than the title backwater or less depending on, depending on the
27:16 range and the size and scale of river. I think I drew this
27:23 last week, but kind of discussed for you. So here's the Mississippi
27:32 there's it's backwater leg. So it's to 1000 m. Okay. And
27:37 dash line represents the point at which base the channel is below sea
27:42 Okay, that's about 750 km Now, the blue line represents the
27:48 of the water when the river is in flood. So that would be
27:52 stage and the yellow line or yellowish , orange line represents the top of
27:59 river when it's the flood. And can kind of see there's an interesting
28:02 . The top of the water has be always at sea level. You
28:06 , you can't get a the waterfall freshwater into saltwater, right, Doesn't
28:10 any sense. So, of when the river is in flood,
28:14 interesting things occur. You know, , the water is pinned to that
28:20 . Try it again, You can't any further seaward and flood. So
28:23 whole river can lift up and that's to, it's interestingly, it causes
28:29 lot of scouring in this area here all of a sudden the river's lifting
28:34 , but it can't lift up at seaward end. So that forces it
28:38 cut down in the most seaward Right? So my students, uh
28:45 wu that is PhD at Rice University went into, into the outcrops looking
28:51 evidence of excess scours as rivers get to the sea because the backwater
28:58 The river is kind of kind of a, you know, it's kind
29:00 like a shovel. You know, there's there's actually a lot of weight
29:03 put it as the river lifts up it causes the river to want to
29:06 down in the in the in the . Word part because it can't lift
29:10 top up. Right. It's impossible lift up what let's see fortress.
29:22 , exactly. I started an example of of of the river uh shifting
29:28 in its buffer profile. Okay. the buttresses facts right now. What
29:35 blended and others. Ah There's Jeff who did the work on the
29:42 And so what this is showing is belt with channel belt with versus
29:52 Okay, so that's the that's the dots. Right? That's telling us
30:03 uh language. So on the bottom is the is the normalized backwater
30:10 So that would be the the actual divided by the back water lake.
30:16 at one would be 77 50 km upstream, divided by the background limit
30:23 km. That's one okay .5 would half of 750s. That would be
30:30 my math here. Uh 325. of them anyway. Um No,
30:40 not right, is it? three and 25. Okay. Um
30:48 Mhm. So I love this And it's it's because it's it's it
30:54 the point that I'm trying to make people trying to figure out what the
30:56 controls Flavius photography? So what what what they realized is. So the
31:02 line represents the migration break, that's migration rate, right? So you
31:06 how the river migrates aggressively? Ah know at about certainly above the backwater
31:14 the river is going crazy. It sort of drops migrates a little
31:19 less at about 1.25 aggressively around a around the back water distance. And
31:28 it gets lower and lower and lower towards the shore line, the the
31:34 leandro when it stops migrate. So channel belts are getting narrower and narrower
31:39 that's exactly what you see with the window. The channel belts are getting
31:44 and narrower. Right? So the belt with divided by thickness is plummeting
31:53 we get to the to the backwater . That makes all sorts of predictions
31:57 what child belt should look like in strata, graphic wedge. Right.
32:02 you're looking at the classic wedge, know, the the channels at the
32:06 end should be now the channel And then as you go vertically up
32:11 the photography, as you move into more proximal part of the system,
32:16 should expect to see the channel belts get wider. Right? And and
32:20 you're in the lower back water you might expect narrow channel belts,
32:24 they might dig quite deep. So, a diagram like this makes
32:28 sorts of predictions about things you want know which is what, what are
32:32 dimensions of channel belts? And they to these things like uh you
32:38 they're relating to things like the backwater . You go, okay, but
32:42 the backward limit again? How do calculate that nature system? Where is
32:45 ? Right. So the baseline is by the slope, the tidal
32:53 And of course over longer scale sea rises and falls. The backwater length
32:59 primarily controlled by the slope in the , but it's independent tidal range,
33:05 there is a title backwater. Um of course the knowledge of backwater Bay
33:10 limits can predict width of channel the depth of channel belts, how
33:16 title faces entitled mud drapes. There in a given system and other key
33:22 of the faces. None of this particularly sequence data graphically oriented. But
33:28 know, I mean part of this is to give you the key information
33:32 to walk, controls the limits and of settlement bodies. Right. Some
33:37 it has to do with photography. other other has to do with
33:40 With these. With these, With boundaries. But of course sequence photography
33:46 also, you know, how to shift through geological time as a function
33:50 the controlling parameters. And how is expressed in terms of a correlate able
33:55 or a feature that you could So when you're doing your assignments,
33:58 might you might think about this and , is there any difference in the
34:03 of the of the of the of sentiment bodies. I'm I'm interpreting based
34:08 where in the classic wedge you are these kinds of ideas I'm putting up
34:12 you predictive tools now in this room now we have a series of things
34:27 up on the tables and these are for students to measure exactly. And
34:38 , what's the lowest, what's the angle that they could measure here?
34:57 say, let's say you're just using standard Brunton compass. Right?
35:00 what's the, you know, you're to measure the dip of something,
35:04 ? What would be the lowest step feel comfortable measure or when you,
35:09 you wrote your angles down what what of, you know, let's say
35:11 bed was dipping. You know, would you measure the dip of
35:15 Of that bed there? Yeah. , yep. Yes, I do
35:34 you. It's a song before. , so you, you, you
35:45 like that to be say 35° Okay. 30 or 35°. Right.
35:52 anybody like to do better than About 35.76231. Would you be happy
36:00 that? Okay, awesome. Would be happy with that number? I
36:10 what's the smallest? What? So You can measure one degree,
36:14 ? What about .1° 0.01°. What about . Okay, so what's that?
36:25 , so the precision of the instrument , is, you know, I
36:30 ? And I've got my little silver , you can barely see even one
36:32 . Right? You know? so rivers flow over over slopes that
36:39 be measured with a bunch of compass they're too small. Right. And
36:43 , you know, how do we these low slopes in ancient sedimentary
36:47 Can't use a Brunton compass. Right there are things like the manic,
36:54 manic demanding equation, which if you the debt of a river and the
36:59 , you can calculate the velocity. there are ways you can estimate the
37:03 independent of slope. And and if know the depth of the river,
37:06 can estimate what the philosophy must have . If you know the grain
37:10 you can calculate the shear stress. you know the shear stress and the
37:14 . You can back calculate the So there are ways to get a
37:17 slope using paleo hydraulic analysis. And there's also a photographic techniques.
37:26 . Have to measure it. I'm , you know, to a first
37:32 . You know, if if a fills up only it's not multi
37:36 then you can assume that Now the of it is there's a channel,
37:46 ? Obviously four. You know, they're Okay. So what's the depth
37:56 ? one m. What's the depth ? seven m. What's the depth
38:01 ? nine m. So what's the the channel again? Right? Now
38:08 you have a well, log the log might just hit the channel
38:13 Now if you have an outcrop, clips like we have in Utah.
38:17 can see the entire channel form so can get the uh Right so yeah
38:22 depth is a bit of a pig you know there's bank, full channel
38:25 , there's mean bank, full channel . There's towel wag depth. The
38:28 would be the deepest part of the but that might be only local
38:32 Um There could be confluence cara So I mean you know there's lots
38:36 different depths and and the river will a different depth at low stage versus
38:40 flood stage. So not a simple . Okay, so here is the
38:50 . Okay and this is an outcrop . And ah have I been through
38:57 with you before? No, we looked at this yet. Right.
39:02 this unit is let me draw So what is that? That's almost
39:10 . A. And then from here here. D. And then are
39:26 then ap and then the then it back to a here is a
39:49 What are these two here? You that? Right? What's 12
40:02 Did you see 12? Yeah, what are the paris sequences doing?
40:15 . And that's what letter or Retro gradation. Right? Um 12
40:30 11 is what P. And From to 11. There's the roll over
40:46 then it's way out here then it down there. So what's that
41:07 What's the letter? So it's Cause its degradation along down stepping dropping
41:14 . D. D. D. . Right then it kind of lifts
41:17 again and shifts back and forth. then once you get in these younger
41:23 of sequences now you start to see channel belts and sizing and see how
41:28 students drawn little channels emphasizing its multi . Okay, so those are the
41:36 , successions. You guys did a job. So we've got we started
41:41 with a largely a with a bit P. Then a little drop than
41:45 are then ap big D. Then went a R. P R an
41:54 D. And then another degradation than pr little presentation, another R.
42:02 . D. And so on and forth. So those are the accommodations
42:07 from that cross section. Now the thing I thought is wait a
42:13 I've got two incised Valleys here and two black lines just represent. And
42:20 I've hung it on a lower Angela, see lower datum and now
42:25 something going on here, it's probably around the bend. I'm getting a
42:28 of strike there, it's not a dip section. So because obviously the
42:32 can't go uphill. Right so you think of that at the cross
42:37 Maybe having a little thought in But you know I thought what what's
42:43 elevation drop into the base of the that will be the base of the
42:47 part of the buffer zone, the deepest point the river ever
42:52 And so that elevation, so the drops 12 m over a distance of
42:57 km. And that gives me a of About 10 of the -3,
43:04 .0009. And and it's pretty consistent You know, pretty consistent. So
43:14 is 30 m over 21 km. was .0014. So again about .001
43:21 both. Uh And then I also calculated the actual slope of the top
43:29 And again, a slope of about , calculate the slope of the degradation
43:35 drop Uh and that was maybe twice steep .002. So now, of
43:43 the river is sinuous. So the line length, the river might be
43:48 than the straight line distance of elevation . Right? So the slope of
43:53 meander river could be would be lower the straight line distance from an upstream
43:56 downstream position at any rate. Uh know, that's actually pretty steep slope
44:02 a river, Right? The Mississippi 10 : -5. The the Ryan
44:06 10 to minus four and the fairness the monastery and they're quite gravelly
44:11 The gravel never quite gets the but the gravel stops pretty close to
44:15 shore line, the gravel, sand gravel, sand transition. So this
44:20 an example of how we can get slopes an ancient system just using a
44:24 graphic method of measurement. We could then look at other harry hydraulic methods
44:30 compare. Okay, on size with , you see the platform,
44:34 So you can just you can see actual elevation drop on the surface.
44:38 only issue is if it's been tilted or subsided. Okay. Mhm.
44:47 the tidal range ah we don't know tidal range in the Faron. We
44:55 it's probably about less than a couple meters. Okay. However, you
45:02 , here's the shore line, right , sandstone and this blue and and
45:08 or teal faces are beautiful faces. so if we sort of look at
45:14 width again, that's a That's a km scale bar there. So it
45:20 like, you know from the shore , the land would limit the shore
45:25 to the on lap on lap limit that of that Laguna faces. Um
45:31 , you know, not quite 10 . So I said with the tidal
45:36 is the, is that the the line would be the tidal range divided
45:46 the slope. And if we know baseline by looking at the on lap
45:50 of of the bay fill faces, can rearrange that equation to estimate the
45:54 range. So it's 10,000 m or km Multiply the slope, which is
46:02 zero three And that gives us a range of three m. That's probably
46:08 bit high, but probably you just some transgression in there. And that
46:12 that the width of the, of bay line is a little bit wider
46:15 the actual limit of the bay line you know, it's the faces of
46:20 . Right? So that the belt sediment is wider than the actual title
46:24 . Makes it makes sense. the fair and backwater limit is a
46:30 kilometers. Mississippi is a few 100 so a big, big difference.
46:43 , and here's the fairer. So a backwater limit of a few kilometers
46:50 and Sandstone in Canada. I worked maybe 30, 40 km and so
46:54 and so forth. Okay, so shorelines aqui boundary, but bay lines
47:00 backwaters are also important. They have controls on the behavior of rivers and
47:05 ultimately controls the width and depth of channel belts. Okay. They also
47:10 the land would limit of marine That's critical if you're trying to find
47:14 gravel sand transition or the limit at you get a lot of mud interspersed
47:18 your reservoirs because of tidal mud Okay. And these backwater effects are
47:25 big reason, you know, when think about a river, it's the
47:29 is flowing as fast as it But the bed load is moving at
47:33 10th of the speed, You the grains are rolling pebble by pebble
47:37 slowly. so the bed load moves in these doomed bed forms and bars
47:43 they move much, much, much fast than the water the water carries
47:48 called the wash loader, suspended load fast as the water, right?
47:52 the bed load moves much more Mhm. As a cold and certain
47:56 never gets to the shore line. ? So it's common that you'll see
48:00 river with boulders in it and then go downstream and not there's not a
48:03 to be found. And it's not the grains are getting are being,
48:06 not because the grains are being rolled become smaller, the big brains just
48:10 being moved moved downstream past the past certain point and it's because the river
48:18 its gradient so it just loses its stress to move grains of a certain
48:22 , right? All this is particularly where the course faces in a
48:26 wedge, you know, or in sedimentary basin and that's what you're exploring
48:31 . Okay. And of course, know, if the slope changes from
48:39 to minus one, Sorry, if slope changes from 10 to the -5
48:45 attend the -4, that's an order magnitude increase in slope, it's still
48:49 very low slope in the absolute But boy, you know, a
48:55 we might think is a fairly small in tilt can really change the way
48:59 behaves okay. And you know, one of the projects that we thought
49:06 doing, I was looking at growth in the gulf and looking at three
49:10 . Seismic data sets to see when cross the growth fault. Do they
49:14 their plan view as a result of on the growth fault? Because that
49:17 change the slope dramatically? Right, . I'm gonna finish off with a
49:28 few more slides there, maybe 10 slides to go. So Back in
49:33 early 90s, there was some big conferences to sort of pull together some
49:40 the thinking about sequence photography and keith and his former supervisor, Pete
49:46 put together this nice paper and I a PG or Js are on non
49:51 sequence photography on the right. They of show the classic paris sequence stacking
49:58 , uh and the associated sea level . Okay, so at high level
50:03 got a grading, accommodations succession, sea levels rising, they've got a
50:08 or recreational accommodation succession repair seeking set stage, they've got degradation and at
50:15 stand, they've got procreation to aggregation a slight uh back stepping of paris
50:22 . And then on the left, indicate what the rivers might be
50:26 So at falling stage, when when level is negative and accommodation is
50:32 the rivers will be tending to in , then at low stand, the
50:37 will tend to fill and as sea reaches its peak, you may start
50:43 get tati influenced alluvial systems and And ultimately, you know, if
50:52 river is confined in a valley, we'll have my computer's one side the
50:57 the other, you know, there's limited window or area for the river
51:01 the river to migrate the balls. once it's no longer the valley it
51:07 go anywhere, which means it's not to be there most of the
51:10 So the river is over there, going to accumulate here? Buddy
51:15 Right, so they point out that stand because there's a much wider area
51:21 the river to occupy. Two things . The actual accommodation increases by orders
51:26 magnitude is simply way more space because way more area that the systems are
51:32 longer confined to the valley and that two things happen. A the systems
51:36 to backstab because they simply can't maintain position at the coast and the system
51:42 tends to become much muddier. the other thing on this diagram is
51:47 sort of imply that high stand tracks are characterized by high sinuous city
51:53 real channels, which is sort of a another word for a meandering
52:00 whereas they suggest that that at falling , you tend to get Los nur
52:08 higher gradient rivers again, which they're to avoid using the word braided,
52:14 because I was kind of a little out of favor when they wrote this
52:17 this paper essentially, that's what they . Now in this diagram, they
52:23 , they have sort of a a through rivers and a dipped you through
52:27 shorelines. Andrew Mallory just stuck the together. And so he's got the
52:33 boundary with him. Incised valley, channel belts in the valley les amalgamation
52:40 you go into the late low stand then retrograde ng shorelines and more isolate
52:46 channel belts as you go into transgressive tracked. Uh Typically the water table
52:52 rise at the maximum flooding surface. a propensity for coals in the floodplain
52:57 the times of highest sea levels and the system turns around and begins to
53:01 grade as you move into the high systems tracked and as a combination
53:06 you tend to get an increased clustering channel belts date. Notice the word
53:12 and braid is not mentioned on this . Okay, although it is implied
53:17 this one, then john Van Wagner his version with sort of a single
53:24 profile, showing amalgamated channel belts associate his low stam's and then isolated channel
53:33 associate with his transgressive systems tracked. and he also points out that low
53:41 systems are typically characterized by multistory sand and uh if you can read that
53:52 rivers. I whereas the the high and transgressive systems tracks are characterized by
54:01 bonds and point bars are produced by kind of streams meandering streams.
54:09 so once again, you now you've this idea that low stands abraded and
54:13 stands are meandering. So once again got this braided meandering dichotomy entering into
54:20 sequence data graphic concepts. Ah right Marriott in Britain did work on paleo
54:28 and they said wait a minute you are all focused on the channel
54:32 What about the police calls? How they change throughout the sequence? So
54:36 said look, so in order to this diagram, you've got a low
54:42 transgressive and Hiestand systems tracked. The vertical lines represent the soils and
54:48 longer the line the more mature the . Okay. They point out that
54:52 sequence boundaries tend to have the most apparently salt because those surfaces are high
54:57 dry for the longest. Okay, the length that the depth of soil
55:03 to decrease towards the valley and the margin is a place of net
55:07 You don't get the soils in the margin. It's really kind of the
55:10 flew away from the actual side of valley that tend to have the deepest
55:15 the modes which are police cells. you should go to the transcription transgressive
55:20 tracked. You get these HYDROmorphone or more wet soils so coldly faces which
55:27 kind of similar to what. Andrew . Said, you get your your
55:31 floodplains and your propensity for calls in transgressive systems tracked. And as you
55:37 up the diagram, you know you from HYDROmorphone soils to less HYDROmorphone
55:43 And finally as you go into the the high stand systems tracked, the
55:47 got more and more mature with time you've got less accommodation and so the
55:52 exposed for longer. Anyway, so should they should have predicted a systematic
56:00 of parenting saul's as a function of data, graphic position. Okay,
56:08 then two more topics and then we'll this lecture. Um This is another
56:18 paper. Yeah. And again remember question I asked, what are people
56:26 avulsion? How does evolution control Graphic architecture. So this is a
56:33 that lets hey Jack and her former , paul Heller and Ben sheets who
56:39 with chris paola worked on. And Dagenham you've got a lower series of
56:49 . The orange represents little crevasse plays the margin and gray would represent your
56:54 shales. Let's say look we've got basin that's subsiding slowly. Okay,
57:00 not much combinations being generated. That us kind of on the bottom of
57:09 diagram here, right, low, level of subsidence. Not much aggravation
57:18 then the basis until we get a of amalgamation of channel belts and caress
57:22 . Then there's an overall change, the basin starts to subside more
57:26 And so all of a sudden you've more floodplain. Unless channel belt,
57:30 an example of a change in the viel stacking that's controlled by a basin
57:34 change in subsidence? Then we have characteristic and size valley model. We've
57:39 the size valleys and mature penny And you get clustering of the channel
57:44 in the valleys and the area outside valleys that represents high, high high
57:49 have more isolated channels and and a of floodplains then. And see they
57:56 a third hypothesis, which is that channels may experience random avulsion. I
58:08 it looks like a braided river, just imagine how it pops out and
58:11 back again. They said that can produce a cluster in the channels that
58:18 a lot of local avulsion going And so they said, you
58:23 is it possible that you can get clusters that aren't related to being sitting
58:29 the incised valleys are related to changes substance in the floodplain, but are
58:34 to this, this avulsion process. once again, investigating the role of
58:39 in control and channel clusters. So looked at two data sets. One
58:46 photo mosaics of the E CN ferris in Wyoming and black is channel belt
58:52 as floodplain. And you can clearly what looked like clusters right? There's
58:59 a cluster here, There is a here? Maybe a cluster there uh
59:10 here and they want to know, these just is it just completely random
59:15 ? Or is it random avulsion? is it local avulsion and local avulsion
59:20 produce a cluster? That's not Then the other dataset they used was
59:27 chris paola flume experiments. You these were bent sheet. Sorry,
59:35 I think he's still doing it on the pale of flu. And so
59:38 notice that the uh this is about couple of centimeters of photography. This
59:45 very this is a small experimental Black is the channel belt and white
59:49 the floodplain sediments. Then they did deal statistics. Okay, perform what's
59:56 a crescent function. I'm not expert statistics and but just to illustrate how
60:02 works, uh is completely random. is obviously not random and she has
60:12 clustering, that's not random. So the crescent function basically plots a so
60:22 bottom axis is essentially normalized distance. . And in the random model,
60:29 black represents the center and the gray the window of points in a completely
60:35 system. And so the plotting of so when you look at the the
60:40 the closeness, you know, so you have a point you can calculate
60:44 likelihood of a point being a certain away. Okay? You're noticing the
60:51 one, you know, because you've extremely tight clusters and then big spaces
60:55 no area at short distances. If have a point, there's a very
61:00 likelihood that there'll be a point next it. And that's clearly not
61:04 So that departs from what we what expect in a random distribution, then
61:10 see that it goes negative. And of course means that at a certain
61:14 there's a high likelihood of not not a point because you're in the middle
61:19 clusters. So then you get a correlation. Okay. And then it
61:24 of settles down in this example the closeness of the points, they
61:30 , there's a greater likelihood of finding point. If you have one
61:35 there's a high likelihood of finding a close to it. That's that's that's
61:39 higher than you expect in a random . So at a distance of about
61:45 from away from the point, uh a there's a high prediction likelihood that
61:51 get points close together. So that mean a an avulsion cluster if they
61:58 channels. All right. So to a long story short, here's the
62:03 from the flume experiments and from the formation. And they showed at distances
62:10 Sort of uh this is mm. that's 50. So there's a bit
62:15 negative correlation that it's positive correlated. there's a slight clustering at about
62:21 but it's fairy random. So not lot of emotion clusters here.
62:26 in the fairest, they just they parted the center of a channel
62:29 not the, not the width of . And I mean, even though
62:32 looks pretty random to me, they that that at distances of great about
62:37 m there tend to be these Okay, now we thought about applying
62:44 to our fair in data. And here's the sequence photography. Sorry
62:51 the rap here. Uh this is stand transgressive systems track the green surfaces
62:59 represent little marine bands uh and calm . The coli faces overlying the marine
63:06 . And they matched the predictive models fairly solid evolution pretty well.
63:11 You've always gotten sized valleys, There's of them. So there's two major
63:15 boundaries and then but the in the you notice that these these clusters of
63:20 and the upper rather muddy your But they do seem these areas where
63:26 have clusters of channels. There's even here. We did talk to Liz
63:31 doing the crest analysis. She said that you don't have enough thickness to
63:36 have the statistics work. So we suggest that they could be involved in
63:41 Anyways. The last two slides I'll about is just a couple of,
63:47 know, a lot of secrets, done in foreland basins partly because they
63:51 and they get stuck up in the and they get a road and you
63:54 see all the geology right in a margin. There's a passive margin substance
64:03 to be great here and it's less it's less and that tends to be
64:08 hinge point. Right. So a margin subsides like that for the basin
64:12 the opposite. Right? It subsides the direction of settlements are coming
64:17 Do you tend to get an area high subsidence and as you go
64:21 an area of low subsidence at some you even get a peripheral bulges that
64:25 part of the basin pops up a bit. Okay, of course.
64:30 all of that's going to change the depending on whether you're in this area
64:33 high subsidence, this area of low . So as an example, you
64:39 , Henry post material. So just there's a sea level drop.
64:42 zone A see that was dropping, the base maybe dropping faster. So
64:47 still creating a combination now, it be less if sea level is
64:52 If sea levels dropping, you it might be your combination might be
64:57 . If it stops dropping, then combination takes over. So what you
65:00 expect is just just to see an similar to this upper effect here,
65:06 accommodation is low, you get clustering is high, you get you get
65:11 expansion. Okay? Yes, from stage. Yeah. So that's on
65:24 right. So then what Henry said look in this zone B where accommodation
65:29 much lower or you have peripheral A sea level drop is likely it's
65:34 to be expressed as a force progression value film, but that same sea
65:38 dropped in the high combination area may have any sequence boundary associated. Just
65:42 change in the amalgamation of channels. right. That's a little introduction to
65:50 marine sequence photography. Let's take a . And when we come back all
65:57 about incised valleys. So it's kind two things I want to talk about
66:10 . Oh. Mhm. Back when was probably around 90 nine, Somewhere
66:19 there, The National Science Foundation. you. I had this big
66:27 what they called source to sink. the idea was they want to get
66:31 bunch of researchers to look at a source system. So some sort of
66:36 real system draining an island and a of oceanographers to look at the offshore
66:44 and try to really, you examine an entire source to sync system
66:49 look for relationships. Typically in the business, we're very focused on the
66:55 . You know, we're we're looking oil and gas in the sediments.
66:59 But sometimes the size and scale of in the sink is related to what's
67:05 on in the source area? And have been a number of times when
67:10 been working on a play and you , the question is, what's the
67:16 quality? Is it nice clean Is it? Is it dirty
67:20 Is it clay rich sand? Is mostly courts, Is that courts have
67:24 specific. Is there heavy minerals, minerals, you know, and a
67:29 a lot of that affects the porosity permeability and the reservoir quality and a
67:34 of that relates to the area that's drained. And if you're, I
67:37 some of the largest amounts of sediment the world are eroded off island arcs
67:44 they're stuck down subduction zones. How oil fields are there in a subduction
67:51 or in the marianas trench? The is most of that stand is has
67:56 volcanic origin and when it gets compressed has no porosity. So you
68:02 it's their marine systems, there could source rock there. But the trick
68:08 volcanic island arcs and the sedimentary basins them is the sediment tends to be
68:13 immature and it tends to be dominated labor minerals such as plastic plays and
68:19 the beans and stuff and they tend break down easily with burial and basically
68:24 up the works and destroy all the . So, so the the source
68:31 sync idea was sort of part of was, you know what inferences?
68:34 the other thing is, you some of this is academic, some
68:39 it is relevant to your business. know, sometimes you want to,
68:43 where where was that land mass? know, if an ocean rifts,
68:48 know, the rivers, the the on one side of the ocean that
68:51 feeding sediments on the other side of ocean when the ocean wasn't there?
68:56 now the source, you know, sort of the atlas mountains are now
68:59 from the sediments that they deposited in North America because the atlantic ocean
69:04 And of course, you can look the composition of the sediments, say
69:07 area was being drained Well, we be eroding our key and rocks were
69:12 appears full thrust belt and that will be indicated by the composition and the
69:18 of the minerals. So to try icons, for instance, can give
69:21 the age of the of the rocks the source area. All right.
69:29 these are diagrams that kind of modified mike bloom. This is his power
69:35 metaphor for source to sync system. , some systems are very large.
69:40 know, if you look at the I'll show you some examples in a
69:43 , you know, the Mississippi drains Rocky Mountains and those rivers flow all
69:47 way to the gulf of Mexico. a continental scale system. And,
69:51 know, you may have uh rises falls of sea level. Right.
69:56 all those do they just change one in a large source to sync
70:01 Right. However, other rivers may start within the within the sort of
70:07 system, such that when the sea drops, the only sediment really available
70:11 dump into a submarine fan is the the material that's evacuated out because of
70:16 fall and the generation of incised valley opposed to a system that's conveying sediment
70:22 a much larger system and that of has a profound difference on,
70:27 the size and shapes of submarine fans you might be exploring for.
70:32 a conveyor belt model that might be continental scale system will produce much larger
70:37 store fans than if you've got very rivers just excavating sediment from a small
70:45 . And again, we go back this idea of of types of channels
70:52 channels on the basis of whether they're , braided or nasty most. But
70:57 like to emphasize the classification of channels to the splitting and joining behavior.
71:03 when you're in the drainage basin or catchment, the system is collecting water
71:09 small channels and delivering them downstream to channels. And so those, that's
71:14 tribute to the tributary system that's commonly the size system, You know,
71:20 systems or what Wiseman partly called contributory typically incised. They will collect the
71:27 and frontally into a trunk system. if the trunk is in size,
71:30 can also get side drainages, so can get tributaries that are small tributaries
71:36 laterally into a trunk system or an tributary system that's draining a larger drainage
71:43 , of course, ultimately the trump un incised, and so at that
71:48 it's free to begin a pulsing or or both. Okay. And then
71:53 get into a distributor very system. . And in a tributary system,
72:00 slopes by definition must be convergent and is distributed system. The slopes by
72:06 must be divert. Right? So very nature of the slope of the
72:09 surface is different. And typically of , if it's an inside system,
72:13 slopes are order of magnitude steeper. also means that, you know,
72:17 incised rivers, even the small ones have a lot of boulders and gravel
72:22 , because they're in size, they don't have a great strata. Graphic
72:25 . Okay. And of course, , 1 of the big questions
72:31 can you distinguish trunk tributary and distribute channels in the system? And it's
72:37 , right? If you find a And you determine that it's a small
72:42 channel, that means you're downstream. could be 100 km downstream. Whereas
72:49 you find a terminal distributor channel, means you're at the end of the
72:53 , there's no likelihood of getting sounds unless there's been a forced regression.
73:00 ? So in exploration, you we we explore in an area.
73:04 you're exploring for structural trap, but want to But one of the deposition
73:08 on that trap, but they proximal distal of a convergent rivers or tributary
73:14 , trunk or distributor, the And then if you know that you
73:18 start wondering what kind of what scale channels deltas and systems do you have
73:26 what kind of films do you And that of course relates to
73:28 what kind of boundaries are present in area? And this is just a
73:35 that's got horizontal resolution, The bottom , vertical resolution on the vertical axis
73:41 from kilometers, two millimeters. And emphasizes that different types of data allow
73:47 types of resolution. So outcrops, know can give you information, you
73:54 , you can get out crops that kilometers high and up to tens of
73:58 wide, sometimes more and so you , you know decipher the size and
74:04 of systems at a wide variety of and our crops in core. You
74:10 have mhm ah there are places where get, I actually was in Russia
74:20 they drilled the Sputnik core and it , it was several kilometers of continuous
74:25 . So I mean, well logs be, You know 20,000 ft
74:30 So you can get a few kilometers well log and you know, most
74:33 are 20 m, but you know you'll get core information that that is
74:39 , Quite extensive in terms of its . But of course the width of
74:42 core is about 10 cm. You get a lot of lateral information.
74:46 logs again can be very deep but again the width of the width of
74:53 of the longest, You know, deep induction law might give you information
74:58 or 10 m away from the well and of course we're interested now today
75:03 channels and channel belts. So the is, you know, what do
75:08 capture in a well log? Do ever see a channel or do you
75:12 a channel belt? And you can distinguish the two? And you're doing
75:15 right now already with the exercises where got one dimensional data and you're trying
75:21 say, okay, there's three channels here. Five channels. You look
75:25 that sharp based finding upward succession. it's, if it's conglomerate capped by
75:30 , you've probably got a full channel if you have a conglomerate and then
75:34 , coarse sand, it rode into another conglomerate, you probably haven't got
75:38 upper part of the fill preserved. ? So that's in the in the
75:41 of, you know, how much the fill is preserved and how can
75:45 approximate the channel death. And of in size valleys can be big things
75:50 you know, depending on the size scale. Seismic data has a vertical
75:55 problem. But obviously you're able to things laterally. So we do have
76:01 on the size of scales of things we can see depending on the
76:05 And then there is, you one of the other big things that
76:08 are trying to predict in the subsurface given that we have lots of information
76:12 the thickness of sediments. Can we predictions about their lateral extent. And
76:18 a lot of people have compiled a of data on sedimentary systems, whether
76:22 be deep water, shallow water. I'll return to this when we talk
76:26 deep water systems tomorrow and I'll talk scaling relationships uh that allowed to predict
76:32 size and scale of deep water systems how how many of you took the
76:38 of systems deposition environments class with Bill , Did he talk about deep water
76:43 ? Much the little bit at the , Yeah, yeah. So I'll
76:49 you a little bit at the very of this class as well.
76:52 But with the two together, you'll a bit, you know, obviously
76:54 water is a big has been a big play for a long time.
76:58 , you'll notice, for example, this compilation here, you've got channel
77:02 that, you know, a single Phil and then a channel belt which
77:07 deposit the channel makes it migrates And of course the thickness of the
77:12 fill the channel belt pretty similar because the channels migrating laterally. Now,
77:17 channel can lift a little bit, know, so the thickness of a
77:20 might be a bit thick, bit than than than the channel Phil.
77:25 you notice that the thickness really overlaps . The only difference is channel belts
77:30 wider, wider in general than channel . Haley valleys cannot be much
77:37 So perry valleys tend to be both because they cut deeper and produce a
77:42 succession of rocks or sediments? And course, because by definition they're both
77:47 and larger than the channel that makes . They paley valleys tend to be
77:52 . Okay, and then in in and pink, we've got the compilations
78:01 giggling who compiled information on bedrock which is the blue data and valleys
78:08 into sediments, which is the pink . And so there's overlap. But
78:12 the data collected by mike bloom, is the his paley valley data and
78:16 additional data that giving collected. But , there's lots of, there's lots
78:21 data around like these. How do use this? Well, here's how
78:26 would use it. Okay, so say that Andrew is giving me a
78:32 and she's pitching a play and she , I've got this 10 m uh
78:39 and I think it's uh, so here. Right. And she
78:43 I think it's It's 10 km then I'm going to say,
78:49 you know, There there aren't many that are that are 10 m deep
78:55 10 km wide it's more likely if a channel belt that it's a kilometer
79:01 . Right? So if you if you want to map that's 10
79:04 , I would say you're at you're at the P 95 You
79:08 in the words there's there's there's only 5% probability, it's going to be
79:12 big. Right, Have you done yet with dawn P 90 p 10
79:20 50. Yeah. So when you when you do, I mean,
79:34 should have done a whole lecture on it. Yeah. Anyway, so
79:37 I assume that you know about this . Ah But anyway, if you're
79:41 an F in a while yet, have to or prospect you have,
79:44 have to do a risk factor, ? And the problem risks the
79:47 So if you're only 50% sure of source rock and 50% during the
79:52 then right away your risk is Which is which means you have to
79:57 four wells to get a success. then if there's only a 50% chance
80:01 the structures holds because of seal Now it's 12.5%. So anyway,
80:07 are multiplication. Okay. And you apply rich to anything, you can
80:11 , well, what's the what's the that your 10 m deep channel Phil
80:16 a 10 kilometer wide channel belter, kilometer wide. You can say,
80:19 , I'm pretty sure that it's at a kilometer wide. I'm going to
80:22 there's a 95%. Certainly it's it's it's a kilometer wide there's only but
80:27 only a 5% chance it could be km wide. That was 10 km
80:32 . It could be a billion barrel field. So very high prize,
80:37 high risk, right? And you know, the least likely cases
80:44 resulting are the bigger things that have , more volume and therefore a bigger
80:49 , right? And oil companies have have to find this match balance between
80:54 risk of a play versus the right? And as I was talking
80:58 Don the other day we had you know, oil companies, you
81:03 that the the riskiest business that oil engage in his exploration and the least
81:09 things they engage in its production. you've got the oil, you
81:13 it's all about just getting the maximum out with the lowest cost to make
81:17 most profit. So you skip off of that money into exploration, which
81:21 much riskier. But why do exploration ? It's so risky? Why would
81:27 want to exploration? It's so What Who cares about that?
81:36 Your production do you want new reserves ? I think actually the value of
81:43 company is based on the value of dollar value of the resource that you
81:48 . And so of course once you it all feel great, you make
81:51 lot of money, maybe trillions of . But once it starts to wind
81:56 , you've got to replace the reserves how does an oil company replaces reserves
82:01 days? No by another company because so risky exploring anyway and there's a
82:11 of people out there that like to but they don't have the money to
82:14 it. So they work and play then they go and sell it,
82:16 try to get someone with money to into their exploration. Right,
82:22 Yeah, I could talk about this day and when I teach my petroleum
82:27 class, I give quite a few on risking and and play analysis
82:32 But I promised I said, the reason for teachers classes to show
82:36 how all this stuff applies to to to to the business decisions that your
82:42 may make right and you need to everything you do in geology at the
82:45 everything. What's the risk that my is correct? What's the risk that
82:50 over correlated? What's the risk that sand is? But the sand is
82:54 than I've mapped? Right, well the risk that there's way more sand
82:57 I think is there? Right. know, because sometimes Risking also is
83:01 missed opportunities. Right. And so diagram like this, this is the
83:05 of diagram you should really internalize. so when you go work in the
83:10 and someone says, yeah, this a channel. Okay, well let
83:13 see, I remember the channels can low net to gross, high net
83:16 growth. They could be wide and and it's controlled by these things.
83:19 that allows you to start thinking? , so is this a high subsidence
83:22 lotion? What kind of basins that basin or rift basin. And they
83:25 , oh that's a rift basin that probably has a high subsidence phase.
83:29 that would be high accommodation. So there's rivers there that that there's lots
83:33 space from the go, you and so maybe there's going to be
83:36 amalgamated channels, right. Whatever it be, or if you're in A
83:40 B. Zone the foreland basin And of course, you know,
83:45 trying to predict the dimensions of of and then this shows that the dimensions
83:50 systems depends on where they are with to the backwater length. Right?
83:55 if they're laminate the backwater, the aren't being that they're not being lifted
83:59 by by by tides and sea So though gravity is basically keeping that
84:04 stuck to the ground and so the tends to migrate laterally, making wide
84:09 belts. If you think about it of is you know, if you
84:13 the concept of the backwater is the level, talking to the river and
84:17 it's annoying, the river, the tends to lift up and if it
84:20 up, you can switch, So so within the backwater the river
84:26 more likely to lift up and switch less likely to migrate, which means
84:31 narrower isolated channel belts, which means quality reservoirs. And then if you
84:36 the title back water you could start have mud drapes. However, if
84:41 in the lowest backwater, it might a little bit extra incision because of
84:44 push during floods. Right? So could get a little sweet spot of
84:48 incisions closer to the shore line. bloom also points out that, you
84:56 , so we've got a couple of here on the on the right is
85:00 he calls, you know, classic period of icehouse period. So you've
85:05 large magnitude or high aptitude sea level and when sea levels low, you
85:11 a lot of area of area that underwater is now exposed. And that
85:17 for more tributary junctions to occur, means you can get much larger rivers
85:22 the downstream. And but during greenhouse when the attitude of sea levels
85:28 the small changes in sea level don't separate drainage systems to coalesce downstream.
85:35 so you tend to get small delta during times of during greenhouse periods.
85:42 the Canterbury Plains in New Zealand, sort of a good example of what
85:46 a a low frequency amplitude sea level might look like you've got relatively small
85:54 to sink systems with braided rivers all way to the coast and lots of
86:01 . And you can drop sea level these rivers are never going to have
86:04 space to join together. Right? the same, the same, the
86:08 delta systems will be the same regardless if you're a high standard low
86:13 That's not true in in, in in a passive margin in an icehouse
86:18 . You know, the low stance fans are much bigger and deltas than
86:22 high stand. Delta's okay, all . And so here's the Ganges brahmaputra
86:29 and you see all you know this there's much more area for these all
86:33 rivers to join together, right? got the Ganges and brahmaputra coming
86:38 And of course they feed, you , one of the biggest deltas in
86:41 world. And of course the the brahmaputra fan is one of the largest
86:47 fans of the as you made up notice the scale there 200 km vs
86:54 km. So completely different scale stores sink systems. So I was kind
87:01 getting into the source to sink game decided to put together paleo drainage maps
87:09 and the downstream systems for north America the entire uh mrs Zoe and and
87:20 . So these are the late Triassic . When Pandya was still assembled,
87:24 had a Himalayan mountain chain down the of Pangea. And you know,
87:29 of those rivers were probably draining, know, So this is the translator
87:33 river system that was mapped by what's name of this Liz miller I think
87:41 stanford. Uh and then the chin dot com system in texas here and
87:47 the these Triassic systems in Canada Um By the late Jurassic you had
87:55 more organized drainage again, still draining Appalachians. Ah and there was a
88:02 and that there was drainage coming from evolving cordillera. So the Rocky Mountains
88:11 well as the Canadian shield and the feeding kind of into Alberta. Uh
88:19 taylor drainage system, was there all way through to the early cretaceous.
88:25 of course these deposit, these incised here are filled with 70 m deep
88:32 belts that are in turn filled No, we want that. We've
88:41 the sediment, the channel belts and channel belts are filled with. Thank
88:48 a little bit. The sand is with what kind of oil? The
88:57 sands. There you go. You , at least one of you knows
89:01 about Canadian patrol geology, but that's you're born in Calgary right. There
89:05 go. So that's the Alberta oil . Right. And they're they're in
89:08 continental scale river that drains the entire north America and of course then you
89:13 a drainage basin here and then you've the, the cretaceous systems in
89:18 Okay, now then the forum base to develop And it split North America
89:25 two subcontinent chlamydia to the west and to the east. And we had
89:32 series of much smaller delta systems And in a time of warmth. And
89:38 we get a lot of small separate . So rivers are never deeper than
89:43 10 m As opposed to the 50 60 m deep rivers that were associated
89:48 the Manville formation, which of course the Alberta oil sands. Okay,
89:54 , foundational, different sources and systems in very different reservoirs. Okay,
90:01 hmm. And as the, as , as the land meteorologically culminated,
90:08 get what's called this kind of mega to which is the belly river in
90:13 and the Mesa verde in in in the States and the Diferente in
90:18 . And eventually, uh, the foreland basin drained seaway drained
90:24 Uh, and this is the present drainage basins. So the drainage basin
90:29 , that the continental divide used to along what's called the transcontinental arch in
90:36 late, later, late cretaceous. , and that area basically subsided.
90:44 now the drainage basin is just south the US Canada border. And so
90:48 got that the, the trans Canadian that drains into in the Hudson's
90:54 Uh, and of course the ST , which is smaller. And then
90:58 got basically paley drainage for the Okay, that produces a big source
91:03 sink systems, Right? These are , the gulf of Mexico deltas and
91:07 fans. That, that, that's the deep water that everybody's growing
91:12 right. All right, little stretch . That, that's kind of my
91:18 source to sink. Uh, lecture it will come back to it
91:23 you know, it's really critical for , it's really, really important for
91:28 making risk predictions about the size and of things. And, you
91:33 one of the beauties of sequence photography that if you have an incised valley
91:37 predicts a low stance seaward. if you have, if you have
91:40 low stand submarine fan, it predicts there might be a submarine that might
91:45 of incised value feeding it right? predicting one systems tracks allow you to
91:51 what's linked to it, both down and up. Okay, so the
91:55 Canyon is obviously the largest in size on Planet Earth today. And there's
92:02 colorado colorado river at the bottom with sand bars in it. And clearly
92:07 doesn't matter how much the colorado the . You know, if you're standing
92:10 the rim, that water is never to wet your feet. Okay.
92:14 of course the Grand Canyon was cut the colorado plateau lifted up as a
92:18 of the flat slab, the transition steep to flat subduction of the Farallon
92:24 in the Laramie. Heterogeneous. so definitions. Remember there'll be definitions
92:30 the quiz tomorrow, I think I I can tell you fairly safely.
92:37 , I've got to be careful I think there's really very little on
92:41 quiz on anything I've lectured today. , Other than stuff that I repeat
92:46 . So if I repeat something that's . But this new stuff, I
92:50 think I've got, I don't think got anything on incised values anyway.
92:54 what if you're studying, don't don't too much time on today's lectures.
92:58 more on what I talked about last . And I'm really happy that you've
93:03 made the attempt of all the exercises going to just help cement things.
93:08 won't be any correlations tomorrow. There will be something that relates to correlation
93:12 the final exam. So even if haven't finished the exercises, I think
93:16 all done enough that you'll be pretty with it. Okay, so values
93:21 elongate irrational feature that is significantly deeper the river that now occupies and the
93:27 and size of which do not routinely the Grand Canyon. Although we call
93:31 a Ghanaian canyon by definition, you , it is a valley according to
93:37 definition. It's an elongate topographic low significantly deep in the river that occupies
93:42 and the walls of which cannot flood the river floods. So it's essentially
93:47 gigantic value. And we also talked the fact that the the the the
93:52 the elongate low is the river. river is under fit with respect to
93:57 topographic feature. It lies now incised are interpreted to form sequence boundaries,
94:07 surfaces that form as a result of level drop. And what else is
94:12 to the size of valley, sea dropped. And for me gotta have
94:20 river system. Yeah. What else required if you want to revert to
94:27 size, what do you have to you have to expose a steeper slope
94:32 have an IQ point. If you a shower slope, the river
94:35 will elevate, right? So that's of important. Right? So sequence
94:41 are interpreted form because of relative sea fall accompanied by an abrupt sea witch
94:46 faces and a basin would shift and lap and also erosion of an incised
94:53 and widespread severity exposure. That could expressed by paleo halls or cars,
94:59 in ancient systems. And of because of the narrow, small length
95:06 time associated with drops of sea level a, on a, on
95:12 on a sine curve like that, that sea level has signed soil.
95:16 an assumption. The Exxon folks assumed these irrational surfaces formed essentially instantaneously or
95:26 a short enough period of time that probably wasn't much deposition going on.
95:32 not a great assumption, I would . It's actually quite wrong. But
95:35 was a simplifying assumption they made, know, back in the, in
95:39 90s, right. And they had lot of one dimensional data that proved
95:44 . But unfortunately it was one dimensional . And if I think about it
95:51 , I can give you the argument tell you where they went wrong.
95:56 of course, okay, now this the third time by showing this
95:58 So that tells you that I think is a very important point. You
96:02 , the valley initiates at the point the slope increases and that's what we
96:07 , you know, it's a nick little knocks that occurs at a
96:10 But of course it occurs along the that defines where that slope break
96:16 Okay. And when we went through slide, you know, the and
96:21 nick point grows with time. So thing to remember is that the size
96:26 the valley, in terms of its is controlled less by the nick point
96:31 more by the amount of time that level is low. So if it
96:35 falls and rises very quickly, there simply not be much time for a
96:39 to do much work. Right? get a small, you know,
96:43 the value won't be very wide. if it sits there for 1000
96:46 like the Colorado River or millions of , then then a river could cut
96:50 very, very, very large topographic all feature. And so the ability
96:55 the riveter road is controlled. The of the depth of erosion. Scope
97:00 controlled by the slope. The depth which the smoke change occurs, the
97:05 of the river to erode the material exposed. Is it bedrock or is
97:09 soft sediment? Obviously the climate plays role. If it's if it's a
97:13 desert, there may not be much for erosion to occur, there was
97:17 more humid environment and it rains more there's more water to do more
97:21 And of course, time is a deal right along the duration of
97:25 the more complex drainage patterns and the and more complex incised valleys can be
97:32 . So here's a series of just cross sections that show, you
97:36 a river that's not in size. in this case the rivers, it's
97:40 stage and it's it's flooding over the and flooding the flood. The flood
97:45 . Okay then, and be the is now in sizing and so at
97:49 level, it can no longer flood the the the the area that used
97:54 be a flood, a flood Of course, this creates a subsidiary
97:59 point. And so any water on floodplain that falls on the floodplain will
98:04 this little notch air. And so will cause value widening. Okay,
98:09 of course, the valley will will roll down to the point at which
98:13 buffer allows it, and that relates the depth of the increase in
98:20 So here's the original floodplain level, are incised valley and that's the the
98:27 , the maximum height of the of channel in in flood. Okay.
98:32 of course, okay, here's another section, I'm showing again. So
98:36 the model for for cutting and filling simple incised value during the falling
98:42 F SST falling falling falling system. systems tracked will force regressive wedge systems
98:50 . We get a decision interestingly keith show some preserved terraces, right,
98:58 that those yellow represent terraces that the left high as it was degrading,
99:04 ? So, you know, there a step in which the valley was
99:08 , then it was lower. And we see the valley is deepening with
99:13 and as it's deepening, it's also a little bit more narrow.
99:16 you know, you stand in the in the Grand Canyon, you look
99:19 and when you cut down the cramped Grand Canyon, it gets narrower and
99:22 , eventually gets the Colorado river, the deepest point and also the narrowest
99:27 the canyon ever gets. Now, the valley is now, then the
99:35 the then you get into low stand the river begins to a grade.
99:40 in this model, the river simply over the original valley and doesn't do
99:45 more lateral erosion. That's not So I'm gonna, I'm gonna We've
99:51 that a little bit and then shot showed that when sea level reaches its
99:57 , you start may start to see influence in the valleys, but that's
100:01 if the valley is within the title and if the valley's way upstream and
100:07 tides are minimal, you won't see title for it. So you need
100:10 be, you know, the value to be fairly close to the sea
100:12 you need to have a title high range to see tidal influence in a
100:16 filled our mantle channels in the tar show title influence Probably 200 km landlord
100:26 the shorelines. There's been a huge of debates as to why it shows
100:30 tidal influence. It's also an extremely developed laterally migrate extreme that shows no
100:37 of lifting so bloom said it's got be louder the backwater but it shows
100:42 insolence. And what option is that was a massive tidal range down
100:48 There's also saltwater trace fossils and the on what they're doing there. One
100:55 is that the tidal water comes in that's hard to believe unless you've got
100:58 massive tidal range, but the tar basically rolled into salts. So it's
101:05 that salt water was actually in the the red river is salty. I
101:09 know if you know that that's because drains evaporates. Right. So some
101:13 are salty because the drain evaporates. , I dry grass and we talked
101:18 that a little bit now. So been thinking about this idea of incised
101:27 for years and oops, probably wondering what I'm doing I guess.
102:38 this guy got a bit messed up here we are at time one and
102:43 see this nice shallow wide valley then level starts to drop and so the
102:48 narrows and deepens here at its lowest , the valleys of its deepest and
102:55 sea level starts to rise and in example, the river starts to cut
103:00 the old value of widening. And so in the end you get
103:05 erosion will scour surface that never existed one time as a geum or fix
103:11 . There was there was a wide valley, narrowed, deepened, and
103:16 as it expanded, the river eroded wider valley but there was once again
103:23 . And so they point out that strata, graphic erosion of surface never
103:29 as a single point in time. they suggested this idea of topographic versus
103:35 , graphic valleys, strata, graphic would be an irrational feature that you
103:39 correlate in a cross section. That necessarily mean that there was a big
103:43 hole that existed at that time and sort of the antithesis of of the
103:51 Mccabe model that says, look, was this great, great big,
103:54 massive hole that existed because of the and that whole never got any bigger
103:59 as it filled up. What what paola group demonstrated is that in fact
104:06 valleys can widen with time. So a little sort of movie. So
104:14 we are at time, one which a shallow wide valley just beginning to
104:20 , then it deepens and narrows deepens narrows the red dot is sea level
104:28 . Then it gets to the lowest and here they show a little widening
104:32 , so it deepens and then cuts . Okay, and then it starts
104:38 shallow and cut some more. So red area used to be the old
104:42 . Now it's gonna rode away and it rises and fails to cut some
104:48 . And then we and then we to the end. And so the
104:51 represents the incised valley fill. The represents the erosion of surface. But
104:57 point out that that surface evolved throughout entire fall to rise cycle, with
105:02 of that of that widening of the occurring late in the filling.
105:07 what they don't show is preservation of is, but so that's another
105:16 So the point they make is that that is that they can this what
105:21 means? Is that the sequence boundary this idea is a single,
105:30 you know, widespread surface without a of sediment on it. It's just
105:34 . An irrational surface. Maybe a bits of lag, right? And
105:39 model, the rivers never migrate laterally channel belts behind. That's not the
105:44 rivers work, Right? So rivers leave channel belts as sea levels
105:49 Uh So they can cut and cover erosion of surface throughout the fall to
105:55 cycle. And that's a very different than Exxon proposed where they said,
106:00 , the system just completely excavated and preservation of the falling stage occurs.
106:06 we think that was a pretty serious . Okay, the blue surface represents
106:13 largest D'Amore Fick value that ever existed the red surface represents the strata graphic
106:18 and the area between the blue line the red line would be these
106:24 these rising and falling stage terraces. so in order to try to help
106:30 understand this couple of things, but I show a cross section in a
106:39 section, you sort of have to the river is kind of coming in
106:42 out of the page. Right. know, anyone cross section, unless
106:46 cross section goes exactly up the acts the river, you're not always gonna
106:51 it on the dip line. So if we imagine, uh,
106:59 know, if we imagine a anna delta, you know, if
107:05 draw a cross section, you I only hit the river at this
107:10 here here at the cross section doesn't the river. So we're imagining the
107:16 section. I'm showing you is from point to be there, it's going
107:23 . Okay. You know, So we are at time one we've got
107:29 little meander about. They're labeled one an orange color And it's feeding Delta
107:34 . Okay, so there's little distributor running across this black surface here.
107:38 I'm, I'm just gonna say the smaller would illustrate, but we've got
107:42 little, maybe a little nick point a seat over there and we've
107:45 so that's the original sequence bounder that black surface there. Okay, now
107:51 let's allow sea level to fall a bit more. Okay, so there's
107:56 old there's the old time one time . Okay, so we've dropped sea
108:05 And now we've got delta number two deposited. Okay. But of course
108:09 above everything about the red line, dashed area have eroded away.
108:15 this area doesn't erode anymore. That has already done its business. So
108:21 we get we cut an extension of of of this irrational surface. So
108:26 got the original sequence boundary. I've red. Then we've got the new
108:31 boundary in two. Of course, new surface has to be on top
108:35 that oil surface. Okay. But rivers are now overriding the delta that
108:41 just fed. And if we continue process, these river channels ride over
108:46 delta is they're feeding it. so now we've got a surface,
108:55 this surface here and the extension of . And the rocks above the sequence
109:05 in this old terrace are older. the delta below the sequence boundary in
109:12 more distal position. You get Right? So there's there's a single
109:18 surface that you correlate and that's riding a delta below it. That's younger
109:26 the than the river above it. that river is preserved terrace. So
109:33 we have older sediments above the surface younger sediments below the surface because the
109:39 is the same age everywhere. So we've got an erosion of surface with
109:44 rocks above and younger rocks below. , wait a minute, a sequence
109:49 is defined as a surface that everywhere older below from younger above. But
109:56 we've got an evolving surface that's diaphanous a little bit of old stuff on
110:01 . And it's building out over over systems below. That violates the definition
110:07 the sequence back. It's not a accurate surface. That makes sense.
110:15 can be tricky to grasp the best of course to show it with the
110:18 diagram. Right? So there is age of the Delta's, right?
110:24 their young wood age. You've had with wheel diagrams. So you should
110:28 able to more or less understand these when I show them. Look at
110:33 age of the of the, of valley fill, right? There's an
110:37 flavor of Olivia Rox, right? was feeding unit one, then there's
110:41 younger channel, it's feeding unit And I can't draw a horizontal line
110:46 that sequence boundary that, that everywhere , you know, in order for
110:52 to be Cronus radical graphically significant. , that channel would have to be
110:56 here. And then I could say , there's a period of time in
110:59 there's no deposits, but because of migration of channel belts that cover over
111:04 evolving sequence boundary, you get these relationships. Okay, that makes
111:12 yep. So, I mean, know, I'm anticipating myself.
111:18 if that was the age of the that would satisfy the definition of a
111:23 boundary as a surface that everywhere separates sediments above from older sediments below.
111:29 if the wheel diagram relationships look like , then it it can't be a
111:35 boundary in the strict definition. So security is the gap in time that
111:42 that that that represents the area that sentiment has been eroded as long as
111:47 empty, then you've got yourself a boundary. If it's not empty,
111:51 it's a bit more complicated. Does make a huge difference while the difference
111:55 makes is whether or not you think is that age or this is
112:00 Right. And if it's younger then means that's filled with transgressive sediments much
112:05 and doesn't have anything to do with with with these systems here. Whereas
112:10 this is filled with the same sediments as that, then it applies that
112:15 sediments were feeding those sediments and that have implications for reservoir quality as well
112:20 paella geographic maps. So the traditional strata graphic view of a sequence boundary
112:26 that although it's never been defined this . If I was going to define
112:29 sequence boundary, I would say it's sequence boundary in which horizontal line could
112:34 drawn with lacuna that separates older and unions. I think I should write
112:41 paper on that and in geology and redefinition of of a sequence boundary,
112:47 if I can get away with And here is the Faron. We
112:54 talked about this because they're nice undulating boundary at the base. And here
113:01 the wheeler diagram. Okay. And a little bit hard to see.
113:07 let me just show you. So my student put together this wheeler diagram
113:14 you know here we have this forced ah seaward stepping wedges. Uh And
113:27 that's ah that's these systems here. down stepping and these systems are down
113:35 and they're fed by that valley Right. So the question is,
113:39 the age of the channels here versus sediment seaward. Okay. And this
113:46 E. J. Kind of just all the valleys up as quite young
113:51 I just took away his valley surface relax the ages of the channels of
113:57 channel belts. In the more language these channels could be as old as
114:02 . I put some I don't I don't have any idea. But
114:06 just said I hypothesized that some of channels could could drop down into the
114:12 and maybe even drop down into the . Okay. And it foundational changes
114:18 understanding of the genetic strata, graphic , you know in sequence? Trickery
114:23 requires definitions. Right? What's the about power sequence? Yeah. And
114:36 the definition of a sequence relatively conform succession bounded by sequence boundaries and the
114:52 conformity. These you know? And with the word genetically related assistance,
114:57 , that genetically related group of de systems. Right, So this this
115:03 of genetic relationship appears in sequence And I just think, you
115:07 the value of the real diagrams. , it's a bit academic, but
115:11 wheeler diagrams tell you what's related in and that that without the wheeler
115:16 you shouldn't be talking about genetic Right. Genetic relationships in time can
115:21 really be fully demonstrated by understanding wheeler or the the time strata, graphic
115:28 . Now bloom. Mike bloom is , you know, a gifted paternity
115:33 . And he got tired of being academic and jump ship and went to
115:37 at Exxon for For about five or years. Anyway. Then he went
115:42 to become an academic needs in Kansas . And he started working on the
115:47 sands. And so he was very to understand how those valley fills in
115:51 oil sands work. And he well, you know, in the
115:55 , you know, a lot of valleys are cut with this sort of
115:58 degradation and it reflects the quaternary. level curves. Right? So this
116:04 uh today, zero, 120,000 years . And you can see that that
116:11 level is falling in hiccups falls a stabilizes, falls a bit more rises
116:16 bit, but never back up to level of laws falls again And eventually
116:20 down at the last glacial maximum 18,000 ago to the lowest level. And
116:25 what happens is the river cuts, , cuts. Maybe it rise a
116:29 bit moves laterally, but then eventually kind of ends up ends down this
116:33 hole, right. And so but lot of people are turning these things
116:38 kind of, you know, but Exxon idea was the cold gets cut
116:42 then the whole valley fills aggregation. excellent. Just did not like the
116:46 of degradation. They didn't like forced in the shorelines and they didn't like
116:51 their values. And so, you , Henry post material promoted forced regression
116:58 he left Exxon. And I think were unhappy with the fact that he
117:04 and I think got real political. I mean to this day that the
117:09 Exxon folks struggle with admitting that anything and that anything is preserved during
117:16 And that's unfortunate because you missed the process but clearly required by the way
117:24 sea level falls in the veterinary. if that kind of steps it will
117:28 occurs in ancient systems, then these degradation patterns should be common in the
117:32 record. Not rare, which was original exile interpretation of course, what
117:38 does is it leaves all these terrorists that, that completely changed the genetic
117:47 and you know in in Alberta in , in those late cretaceous sized
117:55 there are compositional changes. Some of degradation of terraces have different compositions that
118:01 in different die genesis that results in reservoir qualities. And there's lots of
118:06 on that in the uh, the and the other formations equivalents to the
118:11 farther to the west, which are oil and gas fields in Alberta.
118:16 there's at this, there's hard applications understand these differences in how valleys cut
118:21 fill in terms of reservoir quality and genetic relationships. And so bloom sort
118:29 point out the difference in the ages surfaces in low accommodation degradation systems versus
118:35 accommodation systems. But in either he points out that the valley fill
118:41 is dia chris. Okay, here's example that sort of emphasizes the idea
118:49 , that in the strong and pale paper. So here we've got a
118:54 of valley at time one, time two times three and four.
118:59 you can see that the valley is deepening and narrowing, then it
119:04 to fill and widen and eventually, know, shallows and widens a little
119:09 more. And of course, you , here is this master irrational
119:16 Okay, so that's the basil grand fill on conformity, but that's a
119:23 surface formed by complicated both degradation, land aggregation processes during cycles of sea
119:30 rise and falls. So the point , you know, the simple point
119:35 that sequence boundaries aren't so simple and irrational surface do not form instantaneously,
119:41 know, everywhere. there's just this hole they form painfully and slowly with
119:48 deposits of variable ages filling these Then the longer the more amount of
119:54 , the more complex the history of , the more complex the valley fills
119:58 the bigger they are. Okay, right, how about wintertime here,
120:05 other break or keep going for a more, keep going. Okay,
120:12 , so let's talk about how you physically recognize the value. Here is
120:15 nice photograph from uh, from Ron and it shows simple truncation and
120:24 And you've already been drawing this in , in your, in your cross
120:28 , right? Drawing a scour and and stuff. Not a particular concept
120:34 and stuff that, that, that cutting into uh, and the fill
120:38 laps or down lapses the bottom and of the valley. Uh huh.
120:44 here's a photograph of an incised this tectonic valley, the Red river
120:49 Alberta photographed that Henry took that he's into Calgary on one of his many
120:53 and we've got these uh, side , side drainages feeding into the
121:00 the main valley that's occupied by the river and its flood plain. So
121:05 this case, we've got a pretty river that's got a river and floodplain
121:09 the valley system. So whether or the valley fills with channel belt or
121:14 depends on the size of the river the width of the valley, it's
121:17 very wide valley and a very small . Then you can get, you
121:21 , you may get a lot of filling the river. I want to
121:25 out that the erosion in a sea fall by rivers is inefficient because it's
121:31 little rivulets of water. You you can only get erosion where the
121:35 is. You get a bit of and stuff. So as a
121:40 you know, the original, the, the incision is partly scaled
121:44 the, to the age, to the magnitude of the agent,
121:48 is the size and the, and behavior of the river. You
121:52 if it's shifting around, then it cut a wider valley. Thanks,
121:57 values can be seen in seismic I mentioned seismic human ethology when I
122:03 about the seismic and of course seismic has really opened up our ability to
122:09 at ancient morphology is, and topography uh, and both symmetries of both
122:17 and freshwater systems. So this is offshore gulf of Thailand. Of course
122:21 gulf of Thailand is a shelf at last glacial maximum. It was,
122:25 was a flood plain with rivers running it. And because there was a
122:29 , smoke break. Those rivers size these beautiful incised incised valleys,
122:35 the channel is largely mud filled. so it shows up as a black
122:41 , don't drill the channel, you're have mud and one of the big
122:45 people solve these channels said, oh sand and drilled it and like
122:50 you actually drove the abandoned channel. you should have drilled is the area
122:55 to it, which is the old belt. That's where the sand
122:59 Don't drill the mud filled channel. . And then you've got these beautiful
123:04 drainages feeding into this uh nice and river. So there's a classic example
123:09 an incised meander uh and uh the travels in that direction. That's the
123:16 line cross line is perpendicular and you see the scale this valley. It's
123:20 a super big valley, maybe a kilometer or so across here's an example
123:25 Kalimantan, which again shows these dendritic feeding into a central canyon and here
123:34 see the mud filled channel highlighted with black color. Okay, so how
123:39 you recognize the valley? So the story is similar restoring the building.
123:45 it refers to uh one channel Phil be one story. So the story
123:51 essentially the thicknesses story is about equivalent the depth of the channel. Of
123:57 if you're in a valley, the of the valley is much deeper than
124:02 depth of the channel. So the , the valley by definition has to
124:06 up as the river either cuts Lady or Phil's aggregation either way,
124:11 going to produce a multistory film. , if you've got a big river
124:17 the Mississippi that's 17 years deep and cuts of minding me in a deep
124:22 . The valley that, that the is simply too big to get much
124:25 than 1.5 stories. But if you've a 10 m deep river and it
124:30 100 m valley, then you can it up with 10 stories.
124:34 So the number of stories in the fill is also function primarily of the
124:39 point exposure that that controls the overall of incision and then depending on how
124:44 the river is. If the, the depth of the nick point is
124:48 a little bit bigger than the then the river just simply won't cut
124:51 very deep valley. It won't be deeper than the actual river. And
124:56 see that in with really big river can cut valleys, but they're commonly
125:01 as multistory as smaller rivers travel faces not interfere with the floodplain unless the
125:08 is in the valley. And I'll you examples of floodplains in valleys and
125:12 are not in valleys. Ah Valley into fluids are typically associated with periods
125:20 widespread exposure. So that gives you styles and cars, You may have
125:25 flu viel or estuary fills again, on how close the values to the
125:30 and how aggressive the transgression is, big the tidal range in terms of
125:34 marina valley will fill will be, marine, how marines, the sediments
125:39 be that filled the valley. And can see in good seismic data as
125:44 saw the outcrop with truncation and on you can also see that in seismic
125:50 , if the valley is big enough be to be imaged and you may
125:55 multiple episodes of cut and fill ah they can have complex patterns depending on
126:01 it's a forced aggressive degradation of valley or whether it feels mostly during the
126:06 of history. And of course incision both downstream and up steen.
126:12 away from the nick point. unless you encounter another midpoint Lebron Willis
126:17 together these little cartoons and I kind covered them up and it's sort of
126:23 kind of illustrate the difference between an channel and an incised valley. So
126:30 systems are on the left, confined , or valleys are on the
126:34 So valleys on the right, unconfined the left, this would be unconfined
126:41 these will be the incised valleys. imagine a measure section or well logged
126:50 these systems. Okay, here you mud, you've got sound courses upward
126:59 to mud here, you've got sand finding upright and then it's over line
127:08 question upward. Okay, so in case you've got an open questioning pair
127:17 , you're gonna channel that's smaller than paris equals. Okay, so if
127:23 I did was give you, it looks like this, you might
127:31 , well that could be just an question delta, or it could be
127:37 upper coursing delta super post by And you couldn't tell if you just
127:42 a well off, you might well, look, council finds
127:45 but so I'm gonna go for the interpretation. It could be right,
127:49 be wrong. Right. In look at this one here, here's
127:55 paris sequences and then then we go the, into the here muddy.
128:23 here we're back to marine para So now we've got eight bell shaped
128:35 up with feature finds upward, that's twice as thick as the pair of
128:43 to go, like, okay, a mismatch between the scale of the
128:47 finding faces succession and the uh precaution adjacent to it, therefore you can
128:54 a valley in there. Okay. , you know, so if I
128:59 gave you this, well, logs correlate them, you'd say,
129:01 what's the size the scale of the finding unit versus the precaution units to
129:07 ? So I think I've got a . Okay, And you can sort
129:11 go through the exercise with all of block diagrams and in every case,
129:15 know, here we've got, you , here we've got a big block
129:20 Sam's. Okay, and here we've block of sand shale, a block
129:25 sound shale, a block of sand . Okay. And you I
129:30 you could say, well, I that's a valley or you could
129:34 I think it's just fortunate just juxtaposition vaulting channels, right? An avulsion
129:39 . Okay, brian Scotland, Ron for a lot of papers on incised
129:52 . I mean, you know, think they, you know, they
129:56 the idea of shortness valley systems that just have a simple couple Phil.
130:01 once again hit back to our example , we've got 1, 2,
130:11 , 4, 5 para sequences on left. We've got a simple company
130:15 that cuts one para sequence out and little bit of another one. But
130:19 all right, we've got ah a valley that consists of three episodes of
130:25 Phil and the deepest one is cutting three full para sequences. So we
130:32 a mismatch between the scale of the finding valley fill faces versus the
130:38 upward cautioning high stands that represent the units. The valley is cutting into
130:44 I'll show you examples of simple and systems ah in the later alluvial example
130:54 later this afternoon probably. And of coming back to the texas example,
131:09 is a bit interesting when, before mike bloom did his PhD at the
131:14 time. I did. So We graduated about 1989 and he was working
131:21 me aloe strategic graffiti of the quaternary , colorado systems in texas and I
131:29 working on the Alice photography of cretaceous in um, Canada and we met
131:37 this news conference in 1990 and because last name is bl and monty's bh
131:45 stuck us in the same room I never met this guy and we
131:50 it off immediately. Think we're the two people conference that knew what adults
131:54 was. And remember mike, I going fishing, he had this fishing
131:59 , he was going to go fish Banff, I said you can't fish
132:01 the national park without a license and like, sure, yeah, I
132:05 think so. I probably, you , you don't get arrested right?
132:09 , so what problem is he So, so historically, you
132:13 people saw these incisions, right? the decisions that it switches left,
132:19 switches right? And so with the are about, You know, they're
132:23 30 m deep and it's about the of the Mississippi River. So this
132:27 just auto cycling, river switching, ? This is just avulsion. And
132:32 they had a very oughta genic view the strategic graffiti like bloom came
132:36 So wait a minute, you there's, there's paleo halls associated with
132:41 decisions, you know, the river a few meters deep. This decision
132:46 30 m deep or You know 20 deep. He said that's not a
132:51 , that's a, that's, that's small valley and these valleys are
132:57 this is not load switching. And he built, he was one of
133:03 first guys to do, oh, data, you know what that is
133:07 stimulated luminescence. So carbon dating gets back about 10,000 years. Oh sl
133:16 a method where the courts grade is to the sun and it Resets the
133:23 to zero. The coarse grained gets . And radiation in the environment causes
133:30 dislocations in the court's crystal and it it to luminous and the longer the
133:37 crystals buried, the brighter and the luminescence. And so he took course
133:43 these quaternary sands and the luminescence and out that they were way older than
133:50 had thought, You know, 120,000 ? Not not a few 1000 years
133:55 this was not delta switching. stuck that on in we were diagram
134:01 demonstrated that the that this was a erosion surface surface formed Over the last
134:09 years of steps, suitable phone. . And it really forced him to
134:15 thinking about. So again here he's you know, icehouse inter stadio icehouse
134:20 stadio the last glacial maximum. The line represents the sea level change and
134:30 red line is basically showing the sediment . So the sediment discharges is low
134:37 the at the time of incision, is that? Why would sediment discharge
134:46 when when sea levels falling? Because are building up the red line shows
134:59 sediment discharge, right? The amount sediment that's being supplied the system.
135:05 interesting, it's lowest at the time of of of falling sea levels when
135:13 ice building up in the river is and it's a little bit higher when
135:18 get a bit of melting. Why that? This is the water?
135:24 the glaciers are melting, that's an with water. So. Exactly
135:31 When when the ice is building although the rivers are cutting, there's
135:35 water available because there's more more trapped the ice. But when the ice
135:39 a little bit, it adds a of water to the systems that just
135:42 . And that means the settlement discharge up. So it's kind of a
135:45 between when sediments being supplied the system the cutting is going on. So
135:50 again it kind of so we have relation with a lot of settlements supplied
135:53 the cutting happens and that's when that the rivers to migrate laterally and leave
135:59 sandy channel belts right, a little after the main phase of cutting.
136:06 we get periods of of of widening deepening depending on whether the sea levels
136:15 , whether it's a bit more Okay. And so that also,
136:19 know, so when you got valley , your your your your taking sediment
136:24 shunting that in the deep water versus sediment in the valley. So sometimes
136:29 valley storing sediment and sometimes it's exporting . So that has a lot of
136:36 for when you're getting seven sedimentation, fans. And so for the deepwater
136:41 , they need to know how the fans are reacting to sea level
136:45 And that that's very contingent on the of the rivers. Are they widening
136:50 leaving a trail of of sand behind a deepening and exporting? Right.
136:56 during these times exports occurring during these , Sam is being stored in the
137:01 . Right? So this is what expect your major export to the submarine
137:05 . Right. And it's not always that that's exactly coincides with the CW
137:13 . And then, you know, originally said, sea levels fall,
137:19 they rise and they fall and they , boy, they love that
137:23 You saw the pattern. And I , well, wait a minute.
137:26 paternity is not inside and cycle. got this very, very obvious stepped
137:33 progression low stand extremely rapid transgression. . And sometimes it's symmetrical here
137:42 step forced aggression. A prolonged low , extremely rapid transgression, stepped,
137:49 up the forest regression. You and 20,000 year long low stand at
137:56 incredibly rapid transgression. So I well, actually, You know,
138:01 periods of fall make up about 75% the of the cycle. Uh And
138:09 , you know, falling stage and stand closet should dominate the rock
138:13 Transgressive systems track should be rare because know, so, and Exxon,
138:18 they said, well, wait a . There's a very rapid, very
138:21 time occupied by the falls, very time occupied by the rises all the
138:28 is wrapped up in the low stands the high stands. Uh, and
138:32 not the way the world works. know, the, the high stands
138:34 actually pretty short lived, like the melt and then almost immediately begin to
138:39 up against it. There's no wide stand, Right? I mean that's
138:44 stage. That's not high stand. almost no high stands on these
138:48 It's all falling stage and low So there is to me, there's
138:53 big debate in my mind in terms just what's the preserve ability of those
138:58 versus high stands in the rock That becomes important when deciding how to
139:02 Iraq's. Right. Are you looking low stands within low stands or are
139:06 actual high stands and how much is ? So the conclusion from the Colorado
139:13 , is that the bifurcating pattern that initially thought to be auto genic
139:18 distributor channels over a period of a 1000 years Suddenly became Valley incision due
139:25 a complex step fall over 100,000 And that relates to pleistocene glaciation and
139:31 level changes and has nothing to do auto cycle delta switching and that of
139:36 reflects an incredible overuse of the Mississippi . Okay, okay, let's see
139:50 . I, we're going to take break. I've got a little bit
139:54 estuaries to talk about. And then fairly long talk on Identifying Valleys vs
139:59 your channels in the rock record, must be the concluding part of this
140:03 . A lot of examples. So take about 10 minute break and then
140:06 kind of finish this lecture. So a few words on estuaries, you
140:16 , and and I do these reviews a couple of reasons. Not all
140:20 you have done dr price class and know, it's it's good to,
140:25 know, I mean, he, know, I'm assuming he talked about
140:29 Teresa stuff anyway, so I don't these diagrams because, you know,
140:37 almost too simplistic, but this sort shows, you know, once
140:42 we've got a sonia soil, sea curve, we've already said, you
140:47 , that's probably not the way sea works, but you know, it's
140:50 approximation just to give you an you know, sea level certainly does
140:54 . And the fact that it's not more competent chinese toyed, adds
140:58 but it doesn't mean that systems don't to sea level change, right?
141:02 , you know, you could well, yeah, it's it's good
141:05 know that it's, it's complex, , you know, the concept can
141:10 taught without getting into the all the right away. Anyway, so here
141:15 in the falling stage, Right? sea levels falling. And in this
141:20 we cut the hole, right? we're inside the valley, they were
141:24 lowest down. So we deposited a as some sort of shore line at
141:28 mouth of the valley. Then we to transgress. The valley is closed
141:34 by wave dominated barrier. The river now back stacked and it's dumping a
141:40 at the language out of the valley there's a central basin area, which
141:44 , which is not receiving much flu sediment, maybe some of the clay
141:48 isn't receiving much marine sediment because it's cut off by the barrier.
141:52 so that's going to be filled with stuff. May show some title
141:58 So you get the sort of big bay or mud mud plug.
142:04 And then of course they show it Pie stand and again, here's to
142:07 they make a big error. Because you know, at high
142:14 you know, you get to this here, well now the shorelines gonna
142:16 back here and you're going to get Hiestand deltas, right? And of
142:20 eventually those will go from a to so what they're showing here really
142:29 is more here. You know, end of the high stand where the
142:33 has come back. What I don't about it, it's showing these massive
142:37 that are bigger than the low Right? I mean, you
142:40 so I I don't really think that is right, I was going to
142:45 it. I would probably show it bit differently. But anyway, uh
142:50 lot of folks have looked at modern and they, They commonly show this
142:54 part film where there is mostly marine at the seaward end, alluvial sediments
143:02 the landward end, kind of a of flu viel marine sediments in the
143:07 . Okay, now the term estuary a variety of different definitions. Richard
143:20 it as an area of less than salinity. In other words, any
143:26 water environment according to print it is estuary. Ah Damn. Rempel said
143:31 not very good definition because you can't salinity. Then the trace fossil guys
143:36 along as well actually, you brackish water trace false is very distinct
143:41 freshwater marine. So they were we actually can identify variations in salinity
143:48 develop the brackish water faces model. but dad ripples have had none of
143:53 said no, I'm just going to an estuary as a transgressed valley and
144:02 , and but the word estuary comes the word s trees, which refers
144:08 monthly cycles. Okay, you've heard those, I'm sure. And what
144:15 basically means, it has something to with the moon and that basically means
144:21 . So the word estuary, the, the, the, the
144:24 Entomology of the word, that the of the word estuary implies something to
144:29 with monthly cycles. Right? Which means tides. So you could argue
144:35 estuaries have to show some tidal But anyway, that's, that's and
144:43 polls showed two different models for The wave dominant estuary is basically this
144:50 and it hypothesizes that when a valley being transgressed, if it's a wave
144:55 environment, the mouth of the valley closed by a wave dominated barrier.
145:01 mouth of the valley is closed by wave dominated barrier uh and the river
145:07 upstream dumping obey had delta. And we get the central basements, primarily
145:13 and or thin bedded muds and Darren points out that waves that the
145:20 word of the barrier, you've got wave energy, obviously the language and
145:24 got, you've got river currents coming . But the central basin tends to
145:28 an area of low energy in which means that mud can settle that
145:33 a a non reservoir or low quality faces in a valley field. So
145:39 terms of faces models, you one of the big questions if you
145:43 an incised valley, where is the spot to drill? Where's the best
145:46 reservoir in a wave dominate estuary? best quality reservoirs would be behead delta
145:52 your barrier island. In contrast, you're in a situation like the Bay
145:58 Fundy where the tides are extremely then the tides keep the center of
146:03 estuary open all the time and it's high energy area. So it's filled
146:07 sandy title bars. The mud tends be sequestered on the lateral margins of
146:12 estuary producing extensive mudflats, mudflats. see that the Bay of Fundy,
146:17 see that in turning an arm in . So a lot of tide dominated
146:23 have extensive muddy mud flats on the . And the central area where the
146:29 is coming in at all time is dominated. So in that case your
146:33 sequestered in a very different place. you. Then the boy Darren paul
146:40 the guys, you know, they these general model faces models for incised
146:45 systems and they published this this idea segments. Okay, so they
146:50 well, you know, a valley an outer segment which is the area
146:55 , that's dominantly marine. Then it's an inter segment which is dominantly flu
147:01 , that could have a little bit but still within the valley. And
147:05 it kind of a middle segment where kind of marine full of your
147:07 So that's kind of the, the mixed system uh in the middle.
147:13 got systems tracks. So the low systems track will be the low stand
147:18 and the flu viel part of the filled the marine influence part. That's
147:23 or retro traditional, they would put flooding surface on or transgressive surface or
147:29 regressive surface on top of the low and they would find a transgressive systems
147:35 and once the valley's mostly filled and shore line comes back to where it
147:39 at low stand time. They would that as the high stand. So
147:43 got their sequence boundary. Uh They've their transgressive surface which is also that
147:51 regressive surface kind of the same Uh and then they've got their maximum
147:57 surface. They also show that the can sort of do a lot of
148:02 in that area where the waves and river meet. So you can get
148:06 a transgressive surface of erosion that's below point of maximum flooding. Okay,
148:15 just keep keep these extreme models in because we'll come back to them in
148:19 of these examples. Okay, Another little rest break. We're not
148:26 to take a walk and rest, this is just a good stopping point
148:30 digest. So this, there's a of themes I'm going to talk
148:48 but the main one is on distinguishing torrey channels versus incised valleys ah question
148:57 troubled me greatly and with a couple key examples from the pennsylvania cretaceous.
149:12 in 1992, I have had About actually, ah I was contacted by
149:24 walker, I had finished my PhD he said john we're redoing the textbook
149:31 models published by the Geological Association He said, would you like to
149:37 the chapter on Delta's? I said chapter in the textbook like the most
149:42 sold textbook sediment ology but the highest book ever published by the Geological Association
149:48 Canada that every Canadian student uses and used globally. I said sure,
149:53 know, count me in and we a discussion and he said yeah but
149:58 problem is like you said in the version Andrew marr wrote the chapter on
150:02 said, well just ask Andrew write the chapter on rivers, that's
150:05 baby weight. And so that's what did. Anyway, so I went
150:11 you know, doing a PhD thesis suddenly writing a general overview of delta
150:17 . And I was talking about said , do you know any good examples
150:20 ancient bird foot delta? As he , Yeah, the booze turns out
150:25 mispronounced it my students or you build family boat worked in Oklahoma and told
150:32 it's pronounced the bulk. So so I guess I should be called
150:36 boat delta and dan bush back in sixties and seventies produced these maps of
150:44 pennsylvania and both delta as the classic of an ancient Mississippi type bird foot
150:51 . And so I xerox that diagram stuck it faces bottles very happy.
150:59 that was published in 19 92. think we finally got it published.
151:06 then we wind the clock forward to 8 99 and I get a call
151:14 Henry and roger again. They set we're gonna do sort of a Faces
151:19 was revisited but we're not going to this with the Geological Associated Canada,
151:23 going to publish this as a special of S C. P.
151:28 Would you like to write that Sure, I'll do that one.
151:34 but by that time I was, was getting a bit worried about Bradford
151:40 and I published a bunch of examples Distribute your channels in 1992 and I
151:49 that every single one was an incised , like how I thought, I
151:55 what a distributor channel looks like. all these things I mapped as channels
151:59 trunk channels there brother, part of valley system, they're not at the
152:03 of the system. So then I to go back and look at these
152:06 examples and I said, wait a . The ice APAC says, this
152:12 out 40 ft of sand in these , the channels, A 73 m
152:19 distributor rechannel, that's bigger than the . Now, a distributor channel means
152:27 water from one trunk stream is distributed several or maybe several 100 streams.
152:35 the channels, the further down this system you go, the channel should
152:43 smaller. That's how you're paying attention you answer my question correctly. It's
152:50 meant to be intimidating. It just me know that you understand what I'm
152:55 , Right? So thank you for . I appreciate that. It
153:00 It helps make me believe what I'm , you know? Um, And
153:04 like, well I've never heard of 73 million distributor. Now the Mississippi
153:08 the biggest river North America, you , and this is Panja and maybe
153:13 rivers were that big. I wait a minute. There's all
153:16 all these shoestring sands and they just at the shoestring and like rivers don't
153:24 don't do that. They have mouth . Where's the math bar? There's
153:27 math bars here. And then this area is 0-20 ft of sand.
153:33 like 0-20 ft of sand coming out a 0-20 ft of sand coming out
153:40 a 250 deep channel Mike filled with . Like, I don't get it
153:46 . This is where I began to , wait a minute. The scales
153:50 by this map or nonsense. They make any sense. I said,
153:55 should be buckets of sand coming out novels of these rivers because they're all
153:59 way to the terminal land. Then went back and looked at the cross
154:03 , you know, there wasn't much . So the, the,
154:08 the, the book channels are associated the mcallister sand stones and here you
154:17 . Maybe you've got 1234, five coarsening para sequences that paris sequences.
154:25 of them are completely cut out. top of one is partly cut out
154:29 this kind of blocky to maybe finding looking sandstone. The Sandstone is 100
154:39 thick, maybe that's not a maybe that's a multistory system. So
154:48 said, there's a mismatch between the of the adjacent upward cautioning delta front
154:54 that these quote distributor channels erode So I said, you know,
155:01 are probably better interpreters in size Okay, mm hmm. So the
155:08 example I put in my chapter on models as a bird foot delta was
155:14 cleaves and Broussard working on the molding , a Pennsylvanian age once again.
155:22 where the heck is this Alabama? know, remember I was at a
155:28 , the source of the same source sync conference when I met this guy
155:31 was a pathologist at case Western Reserve said, what do you think that
155:37 ? He said, Oh, Incised valley once again. How is
155:43 that you've got no no lobes of coming out of these fingers? Why
155:49 it only the fingers are preserved? should be, there should be fringing
155:53 front sands coming out of all these very channels also kind of. I
155:58 , well, you know, they the flow is the river is flowing
156:02 northwest to southeast. Could that be system going in the opposite direction and
156:10 thickness of these elongate shoestring sand interpreters, distributor channels are 300 ft
156:17 . Well, that's, that's another m deep. Delta. North America
156:23 the pennsylvania, maybe it's Pangea could . So This is a diagram from
156:32 Harms in 1956. And ah actually said this for some years, but
156:43 157% finished. This is Ron Boys based on harms and I think harms
156:50 that these things might be in size . Notice that there's, you
156:54 upward coarsening pair sequences outside the a couple of them and the valley
157:00 much thicker multistory overall, he finds finds upward and erodes into at least
157:08 full pair sequences. There's a mismatch the thickness of the, of the
157:13 finding quote channel Phil and the marine that it's supposed to be associated with
157:21 it's not associated in its cutting them . There's no genetic relationship between this
157:25 upward unit and the rocks adjacent to . So Don Bowen. And ah
157:34 think paul Weimer remap these pennsylvania systems forced them to show a tributary
157:43 So now the delta is a tributary valley lee Christine X. Don't work
157:50 these. He found all sorts of halls. Uh so people have gone
157:56 and looked at this and and clearly reinterpreted as all these pennsylvania systems as
158:02 valleys. The Pennsylvanian folks is also time of the late paleozoic ice
158:09 most have gone to wonderland was in South Pole and there were massive ice
158:13 that grew and and and and retreated they caused extremely high amplitude sea level
158:20 worldwide. So pennsylvania systems in general characterized by marine lime stones eroded by
158:28 valleys. You see that west You see that Oklahoma, you see
158:32 in Alabama, you see that in , you see that in England
158:40 brian Willis who I work with. this was before I worked with him
158:45 was working on another system, interpret a delta burke delta in Wyoming.
158:53 this is the fall river sandstone. Wyoming and north yeah, north Dakota
158:59 think. And it was originally interpreted uh a bird foot delta O'brien reinterpreted
159:08 incised valleys. So the delta interpretation based on maps like these bifurcating shoestring
159:18 . And here is the well log section. We have a sharp based
159:23 upward system and adjacent to it or upward coarsening para sequences. And see
159:33 few of them here. Okay. there's again, clearly a mismatch between
159:38 thick upward fighting unit and the thinner coursing units. It cuts into.
159:43 interpret this as some sort of a meandering channel with levees that inter fingered
159:48 these upward coarsening units. I've looked those in course they're filled with Nikki
159:53 stratification, marine fossils and they're not not floodplain at all. Right,
159:59 faces interpretations made no sense. What's interesting look at the bifurcation
160:05 Mhm. Do you see any wells ? Right. So they have
160:12 you know what I'm saying? I'm saying, why would force us to
160:15 join. Right, so the distributive is forced. You know, it's
160:23 problem with subsurface data. All you is a bunch of holes. You
160:26 to choose how to connect them right? In this case they chose
160:29 delta model and connected them up in distributor the fat pattern. Anyway,
160:37 that sort of says what I thick quote channels eroding into thin upper
160:43 something or other. Let's make it delta. So there's their detailed maps
160:47 there there's the map of the of of the entire powder river basin in
160:52 fall river. And you know, looks like my looks like my my
160:59 black walmart in the wintertime. once again you've got shoestrings and there's
161:06 fringing sand. Like how come there's mouth balls? What's wrong with these
161:10 ? Don't they? Like mouth What about what about a little bit
161:13 a wave dominated sand? I mean do you get these birds put doubts
161:19 the cretaceous. See you in any it's a storm wave dominated sea wave
161:24 course, give it to a good . It kind of looks realistic I
161:27 . You know, So that's the of the delta and okay, they
161:31 some barriers on the margin, but know, little barrier island there,
161:36 not really clear where the hell that and will stand that. But
161:40 and of course why do they make interpretation that's because you know, in
161:43 fifties, sixties and seventies and even eighties, you know, every delta
161:47 in Mississippi and the Mississippi is a for it. There it is.
161:50 just stick that, stick that in , you know, stick down the
161:53 cement, right? You know, ever heard of the *** delta,
161:56 forbid, you know, which might be a better analog, right or
162:00 else, You know? And of , you know, the Mississippi delta
162:04 deep distributor channels all the way to coast. And people forget that there's
162:09 lot of sediment that fringes the Mississippi there's a sub Aquarius component to the
162:15 the to the sediments that's kind of . So they're using just the platform
162:19 the wetlands and then calling that to sand distribution of that. That doesn't
162:24 a whole lot of sense to me and missing is a dominated system.
162:28 scale of the Mississippi is not appropriate may not be. And of course
162:35 interior parks are shallow and don't have shelf slope break and again they have
162:40 fringing sand. So of course brian back and revisited the outcrops. I
162:47 a lot of work on ropes and know, to sort of make the
162:51 short identified these in fact were incised with some questions as to whether the
162:58 descended from one surface or that whether were different valleys of different ages.
163:05 that's why I put a question mark . I think the valley probably extends
163:09 that surface there. But, and here's an example of some of his
163:13 sections and hopefully you can see But uh that that these arrows represent
163:20 currents. But more importantly, you sort of see one up and finding
163:28 awkward finding another awkward finding. So is just like your exercise and so
163:37 have their evidence of multiple stacked, up, finding a prophecy successions.
163:43 of them had ah floodplain and abandoned fill in them. So you've got
163:49 full preserved channel Phil and uh and interpret this as a valley system.
163:56 I talked about simple versus compound Clearly this is a compound valley
164:02 multiple episodes of cut and fill. he interpreted as a large aggregation of
164:08 as opposed to a degradation of How interesting the valley and individual valley
164:15 1050, about 20 m deep. they're not super huge, right?
164:21 the average shore faces. Cretaceous interior gets to it about 20 m.
164:26 when you drop the sea level in margin, the biggest nick point,
164:29 exposed to the shore face. There's there's a flat area, a
164:33 m short face and then a flat . That short face could be about
164:37 or 2° same as the shelf slope . And so the valleys in the
164:41 interior seaway typically are about the scale a short face because that's the nick
164:49 that gets exposed. So back to example, again, you know,
164:53 the well logs that show the upward on the sides and then a nice
164:58 based finding upper unit middle. That out that this family is related to
165:05 , the oil sands. In other , this is the same river that
165:11 all of north America. Okay, is, it's this river here,
165:22 the fall river. So ah the area is kind of in, it's
165:31 of in here. So it's probably tributary branch of the system that ends
165:37 in the Manville, but it's a hefty tributary. Okay, so
165:42 so the fall river channel, they're pretty big in general and brian worked
165:49 the outcrops, the pattern of basin into and even the map that
165:54 you know, fairly big incised river there, the shoreline is hundreds of
166:00 away. So there's a 10 on scale there. So, you know
166:13 channel was 30, 30, 40 deep. It's a pretty good sized
166:19 . And interesting what that means is because it's a really big river,
166:22 it is a 20 m seat of fall plus a 30 m river cut
166:26 a 30 40 m deep hole. ? So it's hard to get super
166:30 story, but you can do But anyway, and so going back
166:47 this slide here, I emphasized the by which you can identify valley,
166:53 know, a much thicker finding up the unit cutting into several pair sequences
166:59 I show in the two right hand , that diagram was directed by bryan
167:06 based on the work that brian Willis on the far river. Okay,
167:09 it's not surprising that those diagrams So he noticed that some of the
167:15 , so he noticed that there were amalgamated valleys. The lower valley is
167:20 a simple cut and fill. The valley represents a value that cut then
167:24 , then cut again and narrowed and filled finally. So it's got three
167:29 of cut and fill and some of phils have a lot of flu viel
167:35 the bottom with todd influenced and then on top. So marine base will
167:41 with increasing marine upwards. Some of films are eschewing from the top to
167:45 bottom. And so Bryant has said of the films seemed to be more
167:52 marine filled, all of them seem be more alluvial filled in some kind
167:55 mixed. And so he had this that some of the, some of
168:00 valley fills tend to have, but major, the major flooding at the
168:04 of the valley. So we call flood capped and in which the values
168:10 largely filled with river deposits and the only at the top and some of
168:13 other valleys were festering sort of all way through. And he called those
168:18 based valleys. Okay. And then got his secret cryptographic cross sections for
168:24 flood capped valley fill versus flood based in the flood cat valley fill there
168:29 a lot more sandy flew viel Phil the flood based the valleys are filled
168:34 more estuarine faces. And going back that the faces model, we sort
168:41 wondered could that mean that some valleys a bit more proximal and distal or
168:46 it mean some valleys have stronger tides other valleys weaker tied. So there
168:50 be different explanations for why these valleys more or less estuary faces.
169:00 Now one of the difficulties with secret is, is what to do with
169:07 , with the valley floor as you see it. Okay, Because eventually
169:14 river has become un incised and they distributor channels and deltas. Right?
169:19 here's a cross section which you've got low stand valley, The valley floor
169:23 rising as you go towards the You might get an area of deeper
169:28 because that backwater effect. But at point, you know, the river
169:32 up feeding distributor channels. So I'm showing that it's kind of a
169:37 , right? A series of distributor associated with an degrading pro grading delta
169:43 , which is the yellow unit, is your upper coursing profile. Notice
169:47 the distributor channel of red sits within upper coarsening. Okay. And of
169:53 that invites a possibility. What was is when I was published in my
169:59 many decades ago, this guy, told you the story, this guy
170:02 Exxon was really trying to push me put the sequence boundary on top of
170:07 sandstone. I said, no, brown Wagner says I should put it
170:11 the sandstone into a correlative conformity. and so I decided to disagree with
170:18 advice from the Exxon reviewer to put sequence boundary on top of the sand
170:24 . And I'm gonna explain why that's in a minute. So, some
170:32 good work done by Ron Steele's research when he was a professor at UT
170:38 . Amazing outcrops in Spitsbergen and uh Norway, ah Spitsbergen and these are
170:48 owned by Norway. And it shows size channels and and and and mouth
170:56 channels which the sort of light green . And they correlates a submarine
171:03 And they're at a shelf slope so that the distributor channel is as
171:07 sebaceous counterpart. And there's clearly hi and low stands. It's and so
171:18 do have a sequence boundary, that's red surface. But look at all
171:21 subsidiary surfaces that are peeling out of sequence boundary, right? When we
171:27 about forced regressions Maybe surface one is first step fall and the sequence boundaries
171:34 culmination. And so you get these like, well, wait a
171:37 Maybe, maybe four should be the boundary, maybe five or six.
171:42 the idea that you can simply correlate surfaces when they so the erosion
171:47 our top lapping against the red surface then they're peeling out as you go
171:53 , resulting in extremely complicated lap part of a variety of clustered irrational
171:59 Good luck and good luck picking up sequence boundary. But ultimately these correlate
172:04 with submarine lobes and sheets. Which is the exploration target, which
172:09 landed emotional surface do they correlate And it can be tricky to
172:15 So here's what gets weird despite the that john Van Wagner clearly said,
172:22 sequence spanish should go below the paris to become a correlative conformity. For
172:29 I'm not clear about. That's not he did. When he did the
172:32 Close Photography, he tipped out of boundaries on top of the deltas.
172:38 ended up with a very strange which I'm going to repeat in the
172:41 lecture, which will probably get to . Okay, he put the sequence
172:48 on top of the deltas. So had low stand valleys that just disappeared
172:56 no deltas that they fed eroding into that have no channels feeding. I
173:06 , that's nonsense. That can't be . But that was the interpretation as
173:11 can see this cross section, all red colors are incised valleys, all
173:15 yellow is delta and pro deltas. you notice that the, that the
173:23 , The Saas Valley faces all tip to a 00 point. And he
173:29 all of the red colored faces as stems and all the yellow and gray
173:37 high stance. And I went ahead put together some wheeler diagrams to illustrate
173:45 time strata, graphic relationships required by Van Wagner's sequence strata, graphic interpretation
173:51 the book, cliffs and in a space you can clearly see you've got
173:55 these lovely sands and shales of a origin, but no river deposits feeding
174:01 . And we've got all these low valley fills that don't feed me
174:06 Okay. The solution of course, to is to split the desert to
174:10 channels and channel belts and then relax ages and then you'll start to get
174:15 that makes makes sense. So, the same book that John Van Wagner
174:22 , he showed this diagram and complained negatively that this was a terribly dreadful
174:29 ST a graphic interpretation and wrong. again disagreed. Foundational e with Van
174:36 point here, I was a bit , he was allowed to publish
174:41 but, you know, it was by a PG in a book that
174:44 paid for in reviewers, john Wagner Wagner Wagner was an editor of the
174:49 . He put the paper in his the book that he edited and he
174:53 sure the review is, we're going accept his opinion. I mean it
174:57 really dreadful. You know, find and say, no, this is
175:01 sequence of photographic interpretation that's not And it's different from yours. And
175:07 made a wheeler diagram to show different , different valleys, feeding different
175:12 right? Uh and I so I no, that the sequence bounties
175:17 So there's your sequence boundary and then is my little zigzag that shows that
175:22 sequence boundary turns to karachi conformity and the river deposits become co evil to
175:28 deltas that they feed. And that's illustrated with the wheel of Viagra.
175:35 question is why is it difficult to out, why is it so easy
175:38 tip out the sequence boundary on top the delta? You know, unless
175:42 have an incised valley cross section that exactly down dip. You know,
175:47 it's gonna cut across the valley margins even here. And so it's
175:53 you know, that could be a valley margin if the cross section goes
175:58 , because you're now you're into the flu. Um but then you go
176:02 down the acts of the delta or it. So it goes down the
176:05 . It could be difficult for someone sticking to the base, but that's
176:08 you really should do. Yeah, , we're now coming up to my
176:21 point or a main point. and it goes back to this,
176:28 kind of personal crisis I had, call it my 1992 crisis where I
176:33 something I published 92 was just completely . And I'm gonna show you some
176:38 these wrong interpretations, I think a bit later. No, I won't
176:42 I talked about those, We'll see . Anyway. Um, so I
176:46 interpreted these big trump valleys that feed Dunvegan formation as an incised valley.
176:52 I talked about that last week and published those incised valley as distributor channel
176:58 , oh no, those room sized . And I said, you
177:02 I don't know what a distributor channel like. I just have no
177:06 So I started looking at modern deltas said, well, okay, let's
177:09 look at some modern deltas and figure about about distributor chances, holy
177:15 Look at the leaner, there is incised valley with bedrock on either
177:19 then the bedrock ends here. So the river starts to bifurcate,
177:24 You've got, you know, stream in that direction, kind of
177:28 sprawled stream going in this direction, going here and then one wrapping around
177:34 , right? That's the first order , then the second order split,
177:38 then, and then you can follow of these threads and splits again and
177:42 it splits again. And when you to the terminal land, The,
177:47 channels have split eight times, So the terminal distributor channels are represented
177:54 orders of splitting. And so the distributor channels or orders of management smaller
178:01 the trunk challenge started with and they're little piddly things that are a few
178:06 deep And maybe 10 m wide. the Trunk River may have been 20
178:10 deep and a km wide. now then I just did a thought
178:16 . I like doing thought experiments once a while and said, just imagine
178:20 I had, I don't know a of holes, drill holes in that
178:25 and I just did a sandman. is what the map would look
178:30 Now that looked to me looks like wave dominated delta clearly isn't right.
178:35 I would say, oh, that's nice margin of sand. No,
178:37 clearly isn't. It's filled with little floodplain lakes. This is a
178:42 , but if there was tides in . So, I mean, it
178:46 map as a simple sound, but would be a very that map would
178:51 a lot of complexity. Okay. so in petroleum geology, you
178:58 these general Mattis we make based on can hide a lot of complexity and
179:05 had an extremely successful, happy, funded career explaining to engineers and geologists
179:14 their maps are very simple and working them to put the complexity in the
179:19 models. So they get the fluid right? And know how to place
179:22 wells right? That's not secret but, you know, the first
179:26 is getting the correlations right? ultimately to kind of figure out what
179:29 internal complexity is, Right? And of course like this depending on how
179:34 focused you are. You know, why you're getting not only sequence
179:38 you're also getting faces models because you've to kind of start putting things
179:43 And then I gave this talk in I said, you know, all
179:49 distributor channel models are wrong. I , deltas grow by sort of growing
179:57 growing and the areas get bigger and and bigger. This is a set
180:02 mythology ideas. So, I give in another course. And I
180:07 you know, you know, I , delta's don't reprogrammed. They build
180:11 build outward and laterally. They just bigger and eventually, unless there's a
180:16 on the change, they get too and they just go somewhere else.
180:19 ? So there's a theoretical limit as how far delta can regress before it
180:24 switches somewhere else. And so I Dave Jamieson. So you're saying the
180:29 don't re progressive, but not No, Delta just can't pro grade
180:33 . Because if the water gets that the combination is too big.
180:38 they just they laterally switch. I , it's again, it's it's it's
180:42 got big. They start to annoy channels that's feeding them and eventually they
180:47 of triggered revulsion. So, we're back to what causes the vultures
180:51 the growing delta load. It's kind like, you know, uh,
180:58 know, like sticking fingers in your . There's too many fingers can't talk
181:02 . You got to go somewhere right? That's not good analogy.
181:05 anyway, but but I said, know, you know, we're interested
181:11 strictly in understanding why delegates the landward seaward and how much that is controlled
181:16 just the system has enough settlement versus , it can't progressed that far.
181:20 it programs that far, there had be something that pulled it right.
181:25 so it forced to start thinking about theoretic limits of probation based on no
181:32 of sea level versus what you need get it to move and how that
181:38 to the scales of channels that have . Now, James is talking at
181:44 at a, at a every four , they have a meeting that looks
181:48 rivers Delta Research River research meetings. one supposed to happen this summer.
181:53 it was, it was postponed again of Covid. And mary Kraus was
181:58 my talk. He said that was great talk. You should publish
182:01 That Js are, it didn't take right away. I said,
182:07 that's a good idea. But it's a half baked. So Carla Lori
182:10 my PhD student. So why don't work on that problem? And he
182:13 a great job. He looked at Systems, previous literature and did a
182:17 of outcrop work and this amazing. so here's an example of the the
182:23 Delta above, which is a small of the Mississippi and the Mississippi
182:29 And what he points out is to these upper coarsening faces successions in the
182:34 . And he points out that the occupy a little bit of the paris
182:39 . And so they're kind of buried the well log, right. And
182:43 why I realized. The problem I is when I was defining distributor challenges
182:49 grad student, the only thing I pick was something that was big enough
182:52 be seen and it was big enough be seen. That means it had
182:55 be big in the paris sequence. than otherwise, it was just a
182:58 , just a little bit of coarse in the middle of a parent
183:02 So I said, I don't know , I don't know what, I
183:04 know what distribution channels look like. then I said, wait a
183:07 The best place to go look for channels outcrops because then you can see
183:11 the clip of sandstone distribute, you see the distributor channel that very
183:16 And I've done buckets of research and lots of papers that describe what distributor
183:20 looked like as a component of a sandy or upward coarsening para secrets.
183:26 not gonna give you those examples today it's too much sediment ology. But
183:31 you can, I can, we time, I could show you a
183:34 of examples tomorrow. And also explain my my my distributional channel stopped before
183:40 end of the sand because there's there's distributor channels, whoops, you should
183:46 them in there. You know, the distribution channels are here,
183:50 They're too small to be resolved with well logs that I had. And
184:06 hard for me to know how many them are or there were.
184:09 so that sort of resolve that And then of course, you
184:14 there's the base of the valley, ? But the low stand delta,
184:20 feeds, it shifted and you this area here is the area of
184:26 distributor channel become narrow, shallow And when the sea came back across
184:32 caesarea, it actually eroded away some those shallow term of this tributary
184:37 And and in the case of the cliffs, the bypass zone, the
184:43 cliffs that that Simon patterson worked on wave dominated and the depth of transgressive
184:49 is quite extreme. The valleys are detached from the low stand deltas that
184:53 feed. And I, you I've shown these slides before. And
184:59 sort of explains the process where you've a little erosion. The depth of
185:03 erosion is linked to the depth of increase in slope, which is the
185:08 point exposed by the drop of sea . And that's only 20 m when
185:13 come back across the top, they easily rode, rode away 8 to
185:17 or 10 to 15 m, so can erode away almost all of the
185:23 , allele degradation all channels. The stuff they leave behind is the gravels
185:27 be moved. They wash those around bit. Remember I showed you all
185:31 pictures of gravel beds, but they originally transported. Rivers formed incised valleys
185:38 the valley is largely gone. And only record left is the few bits
185:42 pieces that were really big. The carried that couldn't be erased or removed
185:47 transgression. And that results in these low stands that that make this isolated
185:53 body that was fed by river. been detached. And now you've got
185:57 beautiful strata graphic trap, this is sand body over land by sealing shales
186:03 by sealing shales. It tilted a , you get the billion barrel Kardian
186:08 , right? And of course it interpreted as what kind of a system
186:11 the 70s. You remember they give whole lecture on this last week.
186:16 was the original interpretation of these isolated stones in the middle of the
186:24 And then remember remember that lecture, think I gave four or 5 interpretations
186:30 sand bodies. Remember any of Oh, so it was the prevailing
186:47 of these Sand stones in the middle the shelf back in the 70s.
186:57 if you guys can remember and that a newer that was a sequence interpretation
187:15 before sequence photography, how they interpreted . Remember at this diagram but shelf
187:52 , we have some shorelines and then had these sand stones in the middle
187:59 the shelf. What was the prevailing of those sand stones in the
188:07 Exactly right. Distal auto. The is that they were interpreted photogenic some
188:14 shelf process magically built this bar of in the middle of the shelves by
188:20 traffic flows interacting with tidal processes. we wiped out that interpretation and replaced
188:29 . Now the scene over dropped, the sand there, but it ripped
188:34 the top. That was my my on top, truncated uh lo stands
188:39 mid stands. Right? What's And we'll see if we have
188:45 You know, we can do some tomorrow. Okay. I do have
188:50 electron shells and all the processes that thought to apply to these offshore bars
188:58 do cause mud to move on the . And that's very important to people
189:04 for mud, mud plays right, not sound unfortunately, or if it
189:08 sad, it's just a very fine . Anyway, so the point is
189:13 history channels are small contained with the contained within the paris sequence on the
189:19 and they broadly conform to walther's Even that little scour valley floors violate
189:25 law by putting flu real rocks over marine rocks that cut deep into paris
189:31 . So there's a mismatch between the of the fill and the paris
189:36 They cut into transgression. Can remove , distributor channels and it can cause
189:44 of the trunk valley from its low delta that feeds and there are
189:50 It's not really a conclusion. It's an add on in wave dominate
189:54 humanity get one or two channels. there are situations where you can get
189:57 rivers that get all the way to sea. Ah and and of course
190:03 big rivers kind of size quite deep the shore line, especially with excess
190:08 , especially when they're in flood because the backwater causes them to dig
190:13 downstream out. These may resemble They typically won't be multistory. And
190:20 I didn't talk about this braided rivers tributary channels come together, you can
190:26 very deep scours at the tributary Those can look like multi story
190:33 values. There's been some papers and which have irritated me that say you
190:38 get multistory sand stones and consulates scours their nonsense. You get a big
190:43 scour. All you get is a bar. You don't get five stacked
190:48 when five rivers come together, get deep hole and it feels almost like
190:51 delta with a big four set. , and we've gone back and demonstrate
190:55 with good field work. So okay, that's it. Um We're
191:02 5:00. Have one more lecture to . I can probably get through it
191:07 today. So let's take a little minute break. Is that okay?
191:12 then we'll start the last lecture, see how far again and well,
191:17 know, Maybe and a little bit , maybe 15, 20 minutes early
191:21 something. I'll just see how far is. So it's on the black
191:34 , like there's a mhm in black and blackboard. You get this
191:48 Yeah, I got all of them there. Oh, I see.
191:53 . Okay. And We've got two scheduled which isn't gonna take all day
192:02 , but I do have some options things we could talk about if you
192:07 , we can talk about some of subjects that you might want some more
192:12 . It's not the kind of stuff would usually test on, but it
192:14 give you some some broader understanding of it's mud stones or carbonates or
192:22 So, the book cliffs has been central area of interest and uh,
192:31 in sequence photography and mm hmm. is, I've already kind of mentioned
192:41 of this. So, here's what rocks look like. This is
192:44 the castle gate at the castle gate it's a beautiful thick better 34 100-foot
192:53 of amalgamated sand widely interpreted as Brandon uh the the area below it where
193:01 can see all the rocks as muddy ah and is the Blackhawk formation the
193:09 is razor sharp. My sharp contact amalgamated alluvial systems above and floodplain dominated
193:18 . If you turn around, that's the black hawk looks like, filled
193:21 black holes. You can see these uh single thread meandering streams.
193:29 Okay. And so indeed, you the, the, the the,
193:33 black hole here looks like it's single streams with well developed lateral accretion
193:41 You go to simulate rocks in southern , the john Henry and the drip
193:48 member. Uh And once again you see a razor sharp contact separating amalgamated
193:55 viel deposits above amalgamated channel belt deposits highlight too gross from a muddy the
194:03 john Henry. If you look you can see some single channels,
194:14 ? Some lateral creation there, you see a little channel belt. And
194:22 was keith shanley's PhD area and that's he kind of got his idea that
194:30 get a sequence boundary over land by sands. He saw some tidal influence
194:35 and there at the top of the and then units like john Henry in
194:39 black Hawk, a mud, mud floodplain dominated. And of course they
194:45 promoted the idea that that low stand were low sanur city braided rivers and
194:51 channels were Hi Cynthia City meandering And this idea was was promoted by
195:01 Wagner who specifically said that low our sand dominated, multistory amalgamated braided
195:08 as as labeled on his diagram. he interpreted the high stand and transgressive
195:15 as single story lateral recruiting point which means he thought they were single
195:20 meandering channels. Yeah. And then course harks back to this idea that
195:26 channels make money, flavia deposits and channels make sand and gravel dominate
195:33 Yet we know from the newer theory the net to gross is controlled by
195:38 frequency migration rate and the degree of and subsidence on the floodplain.
195:45 Okay, now Van Wagner is kind a hazel slide. So, I
195:53 clearly remember him showing this slide at talk at a PG meeting. He
195:59 waving his arms and he's talking about casket rivers losing all the water because
196:05 was a very air environment. And was this big climate change and the
196:08 is just kind of stopped in the of this kind of uh, shadow
196:13 and swampy area. Not sure I a swamp sobriety. He claimed the
196:18 in the channels filtered into the underlying and evaporate. The water just disappeared
196:26 . Um, and this was his of explaining that the un conformity tipped
196:30 on top of the marine sequences Okay. And I thought,
196:37 they also said that he thinks, know, he interpreted as a terminal
196:41 fan, whatever that is. And , you know, coarse grained alluvial
196:45 , you know, closer to the end. So I thought,
196:50 you know, maybe I should look the council Blackhawk contact in this area
196:56 . So that's what I did. , so, you know, Van
197:02 , you know, gave the Mm hmm. He said the Castle
197:07 was deposited in a more arid more arid environment compared to black
197:13 The black hawk has cold, so has to be humid. And he
197:18 , you know, the Castle Gate many rivers in an arid environment because
197:22 was a braided system. But the hawk had fewer rivers meandering system and
197:26 was humid. You got that got , the difference between the interpretations.
197:34 if the Castle gate is an arid mega fan braided and the black hawk
197:40 a wetland muck dominated, meandering rivers less rivers, which river should be
197:49 . The calculator, Blackout Blackhawk, Black Hawk has more water and less
198:01 gotta be bigger. Right on on a channel by channel basis.
198:04 testable by looking at the scale of between the two formations. So,
198:10 the Castle Gate should have more They should be wider and shallower,
198:15 should be shallower and the scales of forms and sedimentary structures should be
198:22 Okay, so now we have a . Of course, yes, we're
198:26 in the foreland basin. I kind showed you these diagrams already, or
198:30 versions in general. You know, overall probation is from west to
198:38 It turns out that's actually a little of a of a That's not right
198:43 . But that was the general paleo for the Blackhawks and casket. They
198:46 always kind of map together way back our early days of meeting with each
198:55 online, I gave a talk on graphic norman clay church. And of
199:00 here is the black and white diagrams show the various schemes for naming the
199:07 and casket and the various formations Right? And rather than go to
199:15 black and white ones, I'll just three. So here's one of the
199:20 ones. This is Wheeler Mallory in and the black hawk is divided
199:24 into sandstone and shale members. in which the shale members are separated
199:32 the market share with an arbitrary vertical off as we talked about. Now
199:38 1957, young uh, began to these tongues of, So here's the
199:48 formation and it's broken up into Spring , Aberdeen, Kenworth members. And
199:53 spring canyon consists of 12345. Aw sandy tongues and he's got a sharp
200:02 on top and a gradation of This is pretty good work from
200:08 So he didn't draw shamanism line. draw a dash line saying,
200:12 the sandstone grades into the, into shale and the top of the,
200:18 these tongues are sharp and they and correlate language into coles. So now
200:23 see that he didn't call the flooding . That's what is. So he
200:27 identified a parasite into the flooding surface the language equivalent into a cold.
200:33 , he did notice that the Castle was everywhere a sharp contact with the
200:38 black hole. And he just he distinguished this inter tugging of non
200:43 Blackhawk and green that passed into short and deltas and ultimately into pro delta
200:50 . So he's got the inland The Laguna faces the literal marine,
200:55 is sand and then the marine which shale. Then we took a step
201:01 in complexity In the 1972 rather than these very vague terms like inland lagoons
201:07 literal marine marine. Now you start see flu real faces. Delta,
201:11 faces, shorelines, faces, delta faces and everything is just one big
201:17 . Okay, and now the Castle is shown as having a spasm relationship
201:22 the black hole black hole. No conformity whatsoever. No pair of
201:28 Just one big fat cheese omelet. , so to me this is a
201:33 back, but this is what people , this is you know what people
201:36 face these analysis. They forgot about and we were very focused on showing
201:41 environments in much more detail, but think they did a worse job than
201:46 . So, I think this is . Anyway, let me get this
201:51 photography and in the Van Wagner sequence . He just kind of stuffed all
201:57 the flu viel into a valley and of the kind of delta to shore
202:01 into a into a high step. he tried to indicate how he thought
202:07 occurred. So here's kind of pro of a unit and then there's a
202:11 system. But the valley never feeds that's overline by another set of paris
202:16 . Then there's a second seat of fall that cuts out all the high
202:21 of this unit and cuts into the stand of the older unit, forming
202:25 low stand valley system. But for reason, then he's got this weird
202:30 level curve. So it's low here high and then falling again. And
202:34 court that fall cuts the second low . And it sort of looks like
202:40 so he's gotta step step, he's these steps sea level rise and then
202:48 . The shape is the exact opposite a fraternity set of the following.
202:52 so then he published this diagram, annoyed me greatly comparing the sequences photographic
202:58 on top with the quote little photography on the bottom. This of
203:04 is all nonsense. Uh and his of the sequence photography, he's got
203:11 casket desert Hiestand sequences feeding as landward they erode into high stand. Uh
203:22 high stands of the grass and desert , but never the Twain shall meet
203:27 rivers don't feed any deltas and deltas fed by many rivers. So it's
203:32 of a very strange looking correlation. I said, well maybe that's not
203:38 little strata. Graphic interpretation. Maybe just a different sequence data, graphic
203:42 to yours, in which we have , you know, incised rivers,
203:47 low stand, deltas in a low , pro delta. It's mostly all
203:50 stand, not much high stand. this interpretation, the different little faces
203:55 placed in the same sequence in Van view, that the different little faces
204:02 placed in different sequences. So all marine shells and marine sand stones are
204:06 in a high stand and all the viel stuffed into a low stand
204:11 Low stand systems track. Anyway, we thought, well let's go ahead
204:17 test just whether or not there's even difference between the castle gate Blackhawk in
204:22 of size and scales channels. you know, most of the regional
204:28 is focused on the distal area where got this thick clip of of casket
204:34 on top of a bunch of marine sequences. And indeed there's, there's
204:39 in the, in the desert, fossils in the tongue. It looks
204:42 there may be some zones missing. not. So what's not so clear
204:47 happening with the casket marine. So the casket flew viel sits on the
204:52 viel black hole. All the previous focus on these areas and very little
204:58 the question mark. So I well let's let's look at that more
205:02 area that's well exposed along Solano Canyon Several 100 km from this area,
205:11 is where all the previous work was . So we thought, let's look
205:14 this area and in Solano Canyon, looks exactly the same as at the
205:20 gate 100 kilometers away. A big of sandstone overlying the muddy Blackhawk floodplain
205:27 flavia. And there's a nice razor contact that separates very little bit of
205:33 has been done in the Black suggesting amalgamated braided rivers. That this
205:38 a massive degree at Brigham Young. a very detailed study never published.
205:43 Justin thesis, there's James Mccracken, buddy of mine looking at the
205:49 there's Dave Macdonald at from the University Aberdeen. These massive accretion sets.
205:57 and stand next to cross bedded sand . And this is part of a
206:03 sand body there you can see that large accretion set that passes into cross
206:11 . So in our study area we a section that was parallel to the
206:15 . The section that was perpendicular flow Based on about 90 to pay the
206:21 measurements. Uh, the parent currents northwest to southeast, the Blackhawk Pro
206:29 in that direction. There's about a difference in the Perry current. That's
206:36 because that pain. The current difference that you've got change in the tilt
206:42 the landscape that suddenly starts to smell a tectonic feature. We also looked
206:48 some thin sections to look at the . We had a bunch of four
206:54 X. And we had, you , a bunch of standard grain
206:58 purely currents are a lot of good . So here's a close up of
207:02 dip section parallel to flow and you see that there is an elongate cliff
207:07 Blackhawk, some floodplain, another Black Channel and then it's over land by
207:13 Castle Gate. Okay, the diagram the bottom just shows the general mapping
207:17 the channel belts. The Black Hawk belts are about 5 to 8 m
207:22 . The cascade channel belts are more And they range from 4 to 7
207:27 thick right away. You'll notice that not a big difference between the scale
207:31 the finding of the finding upward units the Black Hawk versus Castle Gate kind
207:36 , you know, Somewhere between 4-8 . Stick all in. The Black
207:40 might be a little bit bigger, is what was predicted based on the
207:44 story, but not that much We go around the corner now the
207:49 is coming towards you. The middle Channel belt pinched out completely and the
207:54 one is wide. So it goes the whole study area study area is
207:58 that big. This is maybe a m or so of, of
208:04 So the Blackhawk channels very nice. see beautiful trough cross bedded sand stones
208:10 the basil channel overlying these gray but it is filled with plant
208:17 wow, these photographs of myself see faces all these nice faces, photographs
208:27 floodplains. It's a beautiful climbing current sand stones, typical crevasse plays some
208:35 footprints, plant material indicating a humid floodplain. So this is what
208:41 thin sections look like, interestingly. Castle Gate on the on the right
208:46 all courts of course, at The Blackhawk is elliptical tonight with 25%
208:53 fragments. Again, if the Castle environment was arid as Van Wagner
209:01 you shouldn't have chemical weathering. So the providence is the same, you
209:05 have more carbonate. The casket. Black Hawk is a more human
209:09 You expect more chemical weathering of so you might not get as much
209:14 as a rock fragments, but in , you see exactly opposite composition as
209:20 expect from the climate story. the short story is the Castle gate
209:25 a completely different composition again, implying got a different tectonic provenance. So
209:31 lifted up and exposed. But what is exposed, This court's Novak you
209:36 and that is largely what feels feeds castle gate. And even the
209:41 the cascade has kind of a creamy color and the Cat and the Black
209:45 looks a bit a bit more So this sort of third step was
209:52 start looking at the faces architecture. I'm hoping that Bill probably talked about
209:57 kind of, you know, diagrams betting geometries that allow you to identify
210:02 the geographic elements that build de positional . And in rivers, you've got
210:07 forms like ripples and dunes that form that can create lateral downstream, that
210:13 channels to make channel belts that can to make larger settlement bodies.
210:20 And we can distinguish bank attacked point from mid channel braid bars. So
210:27 a betting diagram that Michael did on dip view. Beautiful downstream. Accreting
210:33 downstream recruiting bars, majestic braiding. do have areas where you've got little
210:40 . She knows those are confluence So when, when to, when
210:45 stream splits around a braid bar, splits. That's called the different zone
210:50 it converges in the consulate's own. cuts a little scour and that's what
210:53 look like. Those little little little deeper cuts, right in some places
210:58 got ripples overline cross beds. And we think the ripples of the upper
211:03 stage. So you have, if have ripples over cross beds, then
211:07 can interpret that as a complete bar . Of course the critical thing to
211:12 braiding is to look at the view the flow coming towards you away from
211:17 . Now the flow is towards you lo and behold beautiful by directionally down
211:22 bars. There's one here. So the top of the bar, There's
211:27 bar margin and that requires a channel either side with a braid bar in
211:32 middle. There's another one, there's channel, there is the channel and
211:37 the mounted bar in the middle, arrows on the slide. If they
211:41 down, I mean the flows towards , if they point up the flows
211:44 from you, if they put two , it means flows left to the
211:47 , to the right. So in diagram, you see the parents that
211:51 pointing downstream. Okay, so that you can visually visualize the direction of
211:56 with respect to the bedding diagram. so Michael did abetting diagram at how
212:04 surface, lower surface and the upper . And again, based on the
212:11 on the left, uh was was clear that these are braid bars,
212:16 that's interesting because the black hawk at is unequivocally meandering. But here we're
212:23 , much, much more proximal. even though these are isolated channel
212:28 in case the floodplain, which, to Peter Friend in 19 3 would
212:35 them to be meandering. There. brady. Okay, we can just
212:42 the measured sections together when you put together. You can't distinguish the
212:46 the cross beds or the thickness of fills. You can also do some
212:51 bit of math. You know if know that that the thickness of a
212:54 band. You can infer the height the dune that makes it the bed
212:59 . And then you can infer the depth and there's scaling relationships. And
213:06 use those scaling ships to infer that casket rivers were about 2.5 m
213:12 and the Blackhawk rivers were about 2.5 3 m deep. So not a
213:17 difference in the size and depth of of the Blackhawk or the cascade
213:22 Okay, um Here's some of the so that dune height is 5.3 times
213:29 that thickness. Anyway, those are numbers if you want. And then
213:33 empirical formulas, you can calculate channel and all sorts of stuff. And
213:37 we when we start to do some hydraulic calculations based on the political
213:41 we find that the channel depths, wits and and and and and and
213:46 belt wits are pretty similar for both . And the cross bed thicknesses are
213:52 similar as well. So in general conclude that the Blackhawks channels contain unequivocal
214:01 of midstream braid bars. The visit exhibit both downstream and lateral accretion.
214:07 got nice confluence scours. We don't any change in the flow of your
214:11 between the Blackhawk and Castle gate. no difference influential style, negating the
214:16 that the low standards braided and the stand is meandering. All we see
214:20 a change in net to growth much compatible with the basin wide change in
214:27 . The question then becomes why the in price meandering and they're braided
214:34 And it could be that you're just down the distributed system and maybe the
214:38 of the downstream channels is lower. there could be lots of reasons,
214:43 ? So we may be just looking a more, more distributed system in
214:48 price river outcrops and maybe more attributed . Uh in in in in
214:57 the scales of shams look identical. no evidence for smaller channels, substantially
215:02 channels in the casket. The idea river style can predict sequence jump sequence
215:11 is not well borne out by this and maybe this is one study and
215:18 general idea that the plan view, of ancient river systems can be,
215:24 the critical knowledge to distinguish net to or sequence photography is not well borne
215:32 . And to distinguish meandering from bravest . You've got to do very careful
215:36 , architectural work and it's really, almost impossible to do that with well
215:39 . Of course it can be done some seismic datasets. So I would
215:45 that the sequence trickery version two is . I published this paper, I
215:51 this in I forget 2000 something or 2000 I think after I published
215:59 my colleague Sandy Patterson who I went school with. Ah he's been working
216:05 book post photography for 30 years and measured thousands of sections. And so
216:12 puts john van Wagoner's cross section above the sequence to retake tip out and
216:17 his new work on the bottom. boy, does his work ever differ
216:22 john Van Wagner's. So he contrasts Wagner's interpretation on the left with his
216:29 on the right. It's absolutely clear Simon's Patterson's much more careful work with
216:35 of additional sections in between the rather . Now, there's nothing wrong with
216:39 work that that john van waiting for time. But you know, he
216:44 a handful of measured sections based on limited amount of time that he and
216:49 workers had when they worked on this the few years. They were
216:52 Simon Patterson spent 30 years at it students out And simply had 10 times
216:58 data and ultimately showed that Van Wagner's was wrong, that my interpretation was
217:04 correct and and shows the correlation scenarios the bottom. And then just a
217:11 diagram illustrate that there are there are deep channels, but and they do
217:16 through a couple of pair of There's actually very little evidence for sea
217:19 fall in the black hawk. Mhm. Anyway, I promised that
217:27 talk would not take the full Okay, We are at
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