| 00:15 | Okay, let's see what happens. , we've we've looked at the modern |
|
| 00:22 | foot, and we've looked at the Low Bay LaForce delta, both of |
|
| 00:31 | we've seen in pretty much construction. A's is. But now I want |
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| 00:36 | think about what happens to that delta it as a portion of it is |
|
| 00:43 | . Remember we looked at this? ? We look at the growth |
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| 00:48 | a major distributor. Eri So now happens is what happens when that tributary |
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| 00:54 | abandoned and go someplace else. well, the first thing, of |
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| 00:59 | , clearly is gonna fill the channel pauses and notice it's going to go |
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| 01:04 | the swamp begins to shrink the brackish begins to expand, the whole area |
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| 01:13 | to subside and eventually subside. Insp in it being bearing. And we've |
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| 01:23 | erosion going on here, so we to see erosion on the flanks. |
|
| 01:30 | so let's see what happens. And view Well, here's our active |
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| 01:37 | and we're gonna abandoned it. So here's the active delta and this waas |
|
| 01:47 | acted delta before the abandoned loner. let's look at what happened. First |
|
| 01:52 | all, we're seeing erosion and in , erosion of the delta Front to |
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| 02:00 | reworked into a series of barrier We're also seeing some science so that |
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| 02:14 | , uh, seaward extent of the plane eyes being submerged. And also |
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| 02:22 | wrote it. So a combination of and erosion and the Delta plane because |
|
| 02:30 | submerges is becoming marshy. Okay, draw a cross section through there. |
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| 02:38 | this was the delta. Is it ? So we wrote it here. |
|
| 02:46 | we have a transgressive barrier island submergence , and erosion along the flanks and |
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| 03:00 | here. So that distributor Eri Phil the transition to pee from the previous |
|
| 03:09 | is sitting here. So all of is the construction all phase, and |
|
| 03:17 | they're just kind of thin veneer with destruction will face. Okay, |
|
| 03:26 | if you look at that area and details, that's again what we were |
|
| 03:30 | at as this whole area subsided, ? And he wrote it. |
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| 03:40 | if we look at this section this is is a barrier bar. |
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| 03:46 | is a transgressive Very everything we said holds the difference here Now, Is |
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| 03:53 | what waas a Delta plane has subsided this is transgressed. And of |
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| 04:03 | what we're looking at is washing deposits . Okay, so again, same |
|
| 04:10 | section are saying that you rather a example of this abandonment phases the Shandler |
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| 04:18 | . It was abandoned up 1800 years . And so what we have |
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| 04:24 | um, a Bay area. a lot of coke. Enas. |
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| 04:34 | of reworking of always should deposits Okay, now I got a lot |
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| 04:41 | marsh deposits. Organic Pete's okay. if you look here, all these |
|
| 04:50 | gods that have been hard to uh, those are those air oyster |
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| 04:54 | and those oyster reefs are basically along levies submerged levies or or some urgent |
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| 05:03 | of the distributor Eri channels. of course, that not only topographically |
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| 05:07 | , but they're also course your so they make a great spot for |
|
| 05:12 | . Now there's a Schadler Rylance. the LaForce delta and let me so |
|
| 05:21 | . There's some that are offshore and that are older. Okay, the |
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| 05:28 | that we have, they're still Was that about abandon us 62,000 years |
|
| 05:35 | ? Okay, so by looking at various Delta's, we can reconstruct a |
|
| 05:42 | by which we have the active Delta . Its emergence continued, and then |
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| 05:51 | reoccupation. So let's look at each these stages. Uh, the first |
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| 05:57 | is that, uh, I lost . Okay, eyes, this |
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| 06:03 | A little headlands. So they got of the headlines and spit a creation |
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| 06:10 | bar barrier bar Formacion. Okay, had a different figure, but this |
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| 06:18 | have to do. So we've got it called flanking barrier islands and Rekers |
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| 06:26 | that are from the eroding. Okay, uh, and here we |
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| 06:33 | members of transgressing Barrier Island eso We're to get a title channel, |
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| 06:38 | And maybe a little bit of the spit in the foreshore. Yeah. |
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| 06:45 | , eventually, the subside since outpaces ability of sediment to keep up. |
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| 06:51 | we have a basically a submerged Very . And, uh, I'm |
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| 06:58 | this this I had these redone and I picked up the wrong out of |
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| 07:06 | . So this here also applies for year. Now we got the flood |
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| 07:14 | delta and wash over marsh on a . Thank you. This is our |
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| 07:25 | guessing during your island. Okay. Todd Landlords, the inner soul |
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| 07:35 | the whole thing submerged. In it started here with a simmers barrier |
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| 07:43 | and eventually that submerged barrier island So this is an active summer shoal |
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| 07:54 | migrating, but, um is migrating and is completely by automated. It |
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| 08:02 | coarsening upwards because, of course, . But it's a highly about elevated |
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| 08:09 | that is moving the legal deposits. this is an example. Ship shoulder |
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| 08:20 | ah, president today, with the being within about four liters of |
|
| 08:27 | Okay, so what we see as go from the active delta, we |
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| 08:35 | to a flanking barrier, transgressive barrier Sancho. And if you're gonna put |
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| 08:46 | in active, an abandoned sequence, kept the lagoon show Press our show |
|
| 08:59 | to show crest or some of the the thickness Here. Oh, |
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| 09:08 | First of all, there's a difference scale here can change this Sunday. |
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| 09:16 | this is only 4 m. This 10 m, but the other thing |
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| 09:22 | 10 majors are better. Said that dealt, uh, distributor mouth |
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| 09:27 | something like, No, I see 0 to 10. The thickness here |
|
| 09:33 | grossly underestimate. This is a much section here. Okay. Uh, |
|
| 09:41 | even though this says 68 10 this is on the order of 80 |
|
| 09:48 | , not 8 m. Uh, closer to being right? Yeah. |
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| 09:56 | , if we compare that, this a river dominated pro gravitational point |
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| 10:05 | Okay? And this is the is emergence the destruction will face. |
|
| 10:15 | if we look at this as being active, relatively active channel, |
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| 10:23 | let's imagine what happens when it's That's a do the same things we |
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| 10:31 | before. Imagine that it's bend. only difference is this hasn't factored in |
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| 10:37 | once. Ah, and so let's at the various parts of the cross |
|
| 10:46 | . We've got the outer bar Inter , pro Delta Shell active and abandoned |
|
| 10:55 | . Okay, so if you look the reservoir is the best reservoirs in |
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| 11:02 | channels with lower ones, that portion it, they were the active. |
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| 11:09 | second next best reservoir is the interdistrict . That was at a bar finger |
|
| 11:23 | , Ah, the worst is the channel fill and almost is bad. |
|
| 11:33 | the distant channel a distant bar? ? Okay, so we see our |
|
| 11:44 | reservoirs of being the active channel and Amalgamated Sands of the distributive amount more |
|
| 11:55 | non reservoirs are basically proved delta the in the large. So if we're |
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| 12:03 | at a cross section, uh, , off and, uh, let's |
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| 12:13 | , Let's look it right through We see this coarsening upward sequence we |
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| 12:19 | to this tributary Mount Bar, and it was dropped back down to the |
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| 12:25 | . Now, what would happen if went laterally or offshore? Who's |
|
| 12:32 | the bars going to pinch out So we see this pinch out in |
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| 12:50 | the reservoir face. She's offshore. we look at the Delta channels, |
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| 13:02 | is our active channel. Maybe something this. Uh, this is the |
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| 13:18 | abandonment and late abandoned stage. So go from a complete channel sequence is |
|
| 13:25 | not particularly great up here. Still down here, but a complete channel |
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| 13:33 | to a largely abandoned. The exact of this sequence is going to depend |
|
| 13:42 | how that channel migrated through time. it a barrier bar? Is it |
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| 13:49 | straight channel? Is it to be channel in center? So the nature |
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| 13:52 | the distribute Terry bar deposits is a of the nature of the river. |
|
| 13:58 | now we've got a pro grading Delta active in their instructional phase. |
|
| 14:09 | And, uh, this is pro tau aggregation. Okay, so the |
|
| 14:17 | Delta Tau Delta front toe Marcia, seems pretty straightforward. That's gonna be |
|
| 14:27 | . Okay. And then we're gonna this hair for second. That is |
|
| 14:36 | transgression in flooding due to abandon. , when we come in here, |
|
| 14:43 | still say that lower part of the sequence. But now it's cut out |
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| 14:52 | chance. That's the active. well, that's the distributor, Eri |
|
| 15:01 | . And now we see one Here's the base of one here. |
|
| 15:04 | can't be the same channel. So gonna be something like this. And |
|
| 15:11 | got the Phil here and Phil So we had this bar front is |
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| 15:23 | grading, distribute Terry Bar, sitting and then a channel here channel here |
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| 15:32 | basically aggregation here. So the whole is submerging until here. Now, |
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| 15:48 | is the abandonment face. Yeah, we've got some limestone here and we |
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| 16:00 | a deposits here. And here's one those shoals. So you see how |
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| 16:11 | thinner the destruction, all phases, also look at the lateral variation in |
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| 16:21 | programming patients. So the chore is Delta's to be able to make those |
|
| 16:32 | now, in particular, referred on Delta's because they are the most |
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| 16:39 | Very well, especially something like the Foot Delta. Okay, now, |
|
| 16:47 | talked about this before. We may seen this diagram, but we looked |
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| 16:50 | normal regressions forced regressions and things that the thickness like accumulation, raid or |
|
| 17:01 | story. Okay, so just as held for strand planes, it holds |
|
| 17:06 | Delta's. And in this particular we've got a se transgressive system where |
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| 17:16 | is back stepping pro gradation regression, gradation, regression program nation. |
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| 17:27 | And then we've got was typical of high stand pro gradation regression programmed agent |
|
| 17:34 | . Prue gradation. Okay, so pattern here is basically where there's enough |
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| 17:46 | overall to allow the delta Pro grade in this particular example all the way |
|
| 17:53 | to the show. Fetch now, is causing these intermittent transgressions? |
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| 17:59 | there could be changes in sea but they also are maybe more |
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| 18:04 | changes in the river location by Okay, actually, your second. |
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| 18:21 | , so you can see when I excited. Okay, so here we're |
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| 18:26 | at a situation where sediment accumulation is than sleeping level rises called retro grading |
|
| 18:32 | sequences. Okay, we're increasing. , um it's slower than sea |
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| 18:39 | Rise on this will be had This is a series of Delta's They're |
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| 18:54 | stepping. Shit Show is a reworked island that was developed on, |
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| 19:04 | this delta. There's an even older on older, lower delta. Here |
|
| 19:12 | have a barrier island that hasn't quite . So we see that Siris of |
|
| 19:17 | that we saw and that view that Mab you seen also as this regressive |
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| 19:27 | Equus? Yeah, here's the And then they kind of work, |
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| 19:37 | , back to here, and then start working their way up again to |
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| 19:45 | or the pro gradation of Paris Okay. And that's what we see |
|
| 19:53 | , uh, albeit in my sink . Okay. Now, clearly, |
|
| 20:00 | , click. Sea level changes are , but also within these larger sequence |
|
| 20:08 | , we have transgressions and regressions that related to changes in sediment supply associated |
|
| 20:15 | abandon. Now the other thing toe think about it and we're gonna kind |
|
| 20:20 | put on our size big hand for . We see these big, pro |
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| 20:27 | kind of forms and the kind of said force at top set. I'm |
|
| 20:33 | . We forget the scale here. things are hundreds of meters. And |
|
| 20:37 | down in here, the this little is maybe tens of meters to maybe |
|
| 20:43 | . So the question is, what this really? And typically there Delta |
|
| 20:48 | con forms that indicate the pro gradation the delta all way to the shelf |
|
| 20:56 | . And then once it reaches the edge, you begin to have slope |
|
| 21:03 | . So this point here is the of this shell. It represents these |
|
| 21:09 | Delta's working their way out to them to come shelf edge. Delta's programming |
|
| 21:15 | show now that show pro gradation, is seen here, or vertical accretions |
|
| 21:27 | rep back stepping ah, not only a change in the preservation potential of |
|
| 21:37 | the delta itself, but the Delta's changing with Tom. So, for |
|
| 21:42 | , for things we see with this Delta here is his progres further |
|
| 21:52 | with the old to the young. , uh, it's gonna change shakes |
|
| 22:02 | intensity more. Well, would you it more like this? Uh, |
|
| 22:11 | delta, which is down here as back stepping, he's becoming more of |
|
| 22:23 | this. So that all of these sepak shapes No, there's more to |
|
| 22:32 | that the point that I want you make out of this is that as |
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| 22:36 | delta is crossing crossing the show, just say this is the shell. |
|
| 22:44 | going to change. And as the is transgressing the show, the delta |
|
| 22:50 | will change. So the suggestion here that during that period where the delta |
|
| 22:58 | working across the shelf, it's river . But when it gets to the |
|
| 23:02 | edge, just wave, dominate, then, as it transgresses is even |
|
| 23:07 | weight. The suggestion here is that has to do with the change in |
|
| 23:14 | rate of sediment supply as well as show itself. So, for |
|
| 23:20 | as its transgressing just says, we a wave dominated barrier island, we |
|
| 23:25 | a wave dominated don't as its maximum Dacian. It's gonna be the most |
|
| 23:33 | influenced. We'll see if that whole that works for the Mississippi Delta. |
|
| 23:41 | , Uh if we look at some the shallow water, Delta's preserved in |
|
| 23:47 | ancient. We get an inter interesting here. We've got some Delta's sitting |
|
| 23:53 | here. They look at these things . Okay? And those look like |
|
| 24:03 | type Delta. They are. In , you were tight filters. |
|
| 24:08 | Yet between them, there are pro delta fronts, pro grading, distributed |
|
| 24:18 | that are much thinner and, smaller bed forms. What we're looking |
|
| 24:28 | is distributor Eri mouth bars that are of lately typically thought of And Gilbert |
|
| 24:38 | , we talked about thes with respect change in in River Mount process. |
|
| 24:44 | what we're looking at here is the Dacian into deeper water during relative |
|
| 24:49 | Yeah, here. We got Delta in here. See, that was |
|
| 24:53 | to rise. We're getting some offshore now. We're beginning to get a |
|
| 24:59 | grading melt bar, and we've got whole picked inflow or hypothetical flow |
|
| 25:08 | And then we come up to this sign, and as the water gets |
|
| 25:19 | , we're getting a combination of turbulent and grateful but so hyper picnic. |
|
| 25:27 | so what we see is a transition transgression from early shell to deeper |
|
| 25:45 | You know that could be just wait Shipping. Shifting. Remember, says |
|
| 25:50 | Cee Lo. So it suggests. as a single delta lobe is pro |
|
| 25:56 | into deeper water, it will change shape. And remember what we said |
|
| 26:02 | the Mississippi? They shallow water The Bush was then replaced in this |
|
| 26:14 | , not my pro grade ation but it was replaced by the Mississippi |
|
| 26:20 | grading into deep water. How you ? Oh, we honestly and Gilbert |
|
| 26:24 | here we don't we don't, because this particular example on you're looking at |
|
| 26:35 | picked inflows. You're looking and, , similar water. Oh, I |
|
| 26:45 | summer water densities. And so this rapidly settling out. The problem with |
|
| 26:51 | water than this sipping is that even it's Dean, that plume is so |
|
| 26:59 | . Leah So, Brian, that get that bird foot built. So |
|
| 27:08 | went from a shallow water to deep learning bird foot. Here we |
|
| 27:13 | from a shallow water to a deeper guilt. Okay. And so these |
|
| 27:18 | the kinds of sequences you get with upwards. You can Okay, let's |
|
| 27:30 | look at this Delta like the And here they're called inner shell for |
|
| 27:38 | water deltas. And in this those Delta's is they're abandoned. |
|
| 27:48 | they pro grade off to the shelf . And once that the shelf |
|
| 27:55 | a lot of things happen that we see elsewhere. But what we need |
|
| 28:00 | think about is the modern Mississippi Food is in between. What about |
|
| 28:11 | ? Yeah, So the the LaForce the inner shell. The modern bird |
|
| 28:18 | represents mid shell, and if it be allowed to get all the way |
|
| 28:24 | the shelf, it would be a . Now, these are some of |
|
| 28:28 | characteristics from the inter platform to the margin. And I'm not gonna get |
|
| 28:33 | those. I'd like you to look those at your leisure, but a |
|
| 28:37 | things your obvious, uh, All right. The Delta is not |
|
| 28:43 | steep, and all of a sudden hits here really big con forms, |
|
| 28:49 | . And that's what this is. lot of deformation of the Mississippi is |
|
| 28:57 | a hint of that much more We're going to get a Siris of |
|
| 29:05 | channels and low, but now these air not mud lobes. These air |
|
| 29:10 | sandy lobes, these air going to Turbodyne moves. And as we'll |
|
| 29:18 | we make really great into letting some channels here. Okay, a lot |
|
| 29:26 | loaves, A lot of deformation. , I'm picking. The flows can |
|
| 29:33 | anywhere characteristic of pipe Piper picked I'm not gonna go into that |
|
| 29:39 | but they are characteristic of Delta's that in deeper water, and they most |
|
| 29:46 | occur as shelf. It's Delta's, they're not restricted to that, as |
|
| 29:50 | saw with Deep Lake deposits. one of the things about Deltas, |
|
| 29:59 | opposed to some of our other is that we get, well, |
|
| 30:08 | finding storm deposits. These are our lines, but we also get, |
|
| 30:17 | it called fluid much and fluid. is a very high concentration mud that |
|
| 30:22 | out in a flood that tells you you're near a river's mouth. So |
|
| 30:29 | presence of that high concentration fluid mud a good measure approximately two rivers, |
|
| 30:37 | that you're in a pro gaining off system. It's also the deposition on |
|
| 30:45 | mud that gives us a lot of soft sentiment information. Okay, so |
|
| 30:53 | is a which refer to is a shell margin Delta. Okay, pretty |
|
| 30:59 | forward. Uh, I mentioned these and love because we're gonna look at |
|
| 31:05 | but that this afternoon. But one them, this is a high stance |
|
| 31:11 | this. Was the shelf inflow graded ? So this would just be an |
|
| 31:19 | of that pro grading with the debris and other types of self sentiment |
|
| 31:26 | But if this is stable, what if it's not unstable? Margin is |
|
| 31:32 | more common. And so here we a whole series of down to the |
|
| 31:39 | growth falls. This thickening can be huge compared to the thickness. Just |
|
| 31:48 | a subsides and procreation. Okay, here we've got an unstable margin. |
|
| 31:56 | got growth false up in here in fault. This is five kilometers. |
|
| 32:04 | these are greatly thickened deposits in these , as this delta system is pro |
|
| 32:14 | out something like this. Okay, our Hiestand Deltas are low stand. |
|
| 32:21 | with faulting you re working and the series of things submarine fans notice |
|
| 32:31 | Well, some morphology. This are emitter mathematic high. So we've got |
|
| 32:38 | rivers that are pausing pond id turbid basins. Many basins here. So |
|
| 32:46 | we see is that as the sentiment loaded at the show veg and as |
|
| 32:50 | begins to the form it not only is the death imagery but also causes |
|
| 33:01 | complex pattern for trapping set. So , for example, we have ah |
|
| 33:07 | . But I feel pond another a night filled pond, greatly thickened |
|
| 33:15 | fronts and not uncommonly kind of a alone here. What's the examples of |
|
| 33:23 | , too? Eyes not unlike a landslide with failure rotation compression. |
|
| 33:34 | so here we've got the shell Waterloo working out to mid shelf. I |
|
| 33:40 | this is gonna be more like a foot If it's a big river, |
|
| 33:45 | out here and then what happens? . Estuary they had dealt. This |
|
| 33:54 | your ST Louis now. We talked about the programs a pro gradation that |
|
| 34:03 | across all the way and that's called supply driven shelf edge Delta if there |
|
| 34:09 | enough sediment to make it all way , usually we say a forced regression |
|
| 34:18 | the sentiment is getting across the shelf the shelf has become emerging at sea |
|
| 34:26 | is dropping, so that would be forced progression. Okay, In both |
|
| 34:38 | , we could get a shelf No, if you were to look |
|
| 34:47 | the rate at which Delta's a pro , um were set well, the |
|
| 34:55 | , which seven is being supplied and to look at how long it would |
|
| 35:03 | to pro grade across the show according in this city might make it. |
|
| 35:11 | it doesn't evolves, it is going evolve to don't work in many 5000 |
|
| 35:18 | . Uh, denial. On the hand, 25,000 in a subset of |
|
| 35:22 | here simply will never make it They will never be a their rates |
|
| 35:29 | pro gradation or so slow. And shelf is so live that they will |
|
| 35:34 | become a shelf edge. I'm a supply driven shelf built for these |
|
| 35:41 | to make it across like the You have broken Cee Lo, which |
|
| 35:45 | and have a force progression, which of course, what happened. |
|
| 35:49 | so this could be the process. this is very typical coming forced |
|
| 35:58 | Now, one other thing to keep mind is here's the old shell |
|
| 36:07 | Sea level began a pro grade Look, what happens is to go |
|
| 36:12 | that shallow too steep area. but we looked at that and we |
|
| 36:17 | at how that gave us that But what we didn't realize at the |
|
| 36:25 | was it. When that happens, you begin to program it past the |
|
| 36:31 | , that lower show margin, that shell often becomes the site of a |
|
| 36:40 | failure here. And so, if was a shelf edge delta to shelf |
|
| 36:51 | . Now we got encrypted regional fault here as to progres past it. |
|
| 36:59 | as two stops a new shelf edge then we programmed past it. We |
|
| 37:07 | a new shellfish controlled fault these the origins of these regional growth fall |
|
| 37:17 | that we see all on the co Coast. They typically are located at |
|
| 37:22 | shelf edge of an underlying. Just Wilcock shell break his will. So |
|
| 37:27 | see this in pro grading coastal And of course, they're going to |
|
| 37:34 | us these large. I have a of it. These large breaks, |
|
| 37:44 | are regional scale came now, the than happened. We were coming across |
|
| 37:51 | and instead of this, making it and having a large head. You |
|
| 37:55 | have basically a landslide occurring here, you're creating a failure plane that's moving |
|
| 38:12 | fairly catastrophic. And so we get Siris of rotated blocks here and then |
|
| 38:20 | chaotic slide, which I'll call a transport complex. So this here, |
|
| 38:27 | failure again is following the old but is not The shelf edge |
|
| 38:33 | The shell itself is the surface of Cold War, and in some cases |
|
| 38:41 | get reservoirs that have been displaced trapped these shelf scars. In other |
|
| 38:50 | the area remains completely evacuated and is later filled with mud. So we'll |
|
| 38:58 | this a swell, and in some it will be filled with a pro |
|
| 39:05 | delta. It starts all over Now, little growth falls are real |
|
| 39:15 | in Delta's. This is just some okay, um, and this is |
|
| 39:25 | they look like. Notice it Soling all pretty much at the base |
|
| 39:32 | the Delta complex. So these aren't kind of faults that will be a |
|
| 39:39 | edge failure, but it's a common of growth faulting at the delta mouth |
|
| 39:49 | on the other hand, we can a look at some large areas where |
|
| 39:54 | shelf has collapsed. And now this on area. In Norway, the |
|
| 40:00 | quotations collapse, rotated blocks. And we've got a pro grading Delta front |
|
| 40:12 | blow It are a series of turbid ICTs And then the whole thing |
|
| 40:17 | covered. Do you care? That's this is. If there, I'll |
|
| 40:22 | you a hint. The guy who this for the Wilcox also had worked |
|
| 40:27 | Norway before. So this diagram is on this exposure in a fjord, |
|
| 40:34 | . And something like this now is from right to left. Here's a |
|
| 40:41 | here is surface. Now look at Delta pro grading out here and then |
|
| 40:56 | plane. Same thing here. Broken . Maybe we talked about the delta |
|
| 41:08 | being trapped in these local blocks, then the Phil, which is basically |
|
| 41:15 | and the programing delta and then delta . Okay. Okay. So this |
|
| 41:26 | just some examples of deformation. Quit for Delta's and I've got to take |
|
| 41:33 | five minute break so I can record , and you can get your notes |
|
| 41:37 | for deep water. Okay, So back in about five minutes or |
|
