| 00:09 | All right, good morning. Just of you guys today. Okay. |
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| 00:19 | any any questions about what we covered about the reefs or the sands? |
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| 00:31 | it's not all. I'll give you guidelines here about the next exam and |
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| 00:39 | kind of stuff I think you should familiar with for both of those |
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| 00:43 | Um we're going to continue our discussion the other carbonate sedimentary environments. Oh |
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| 00:55 | . And talk about what happens. want to come back to the northern |
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| 00:58 | because you saw that keiko's platform was dominated by grain stones. Right, |
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| 01:03 | energy. So it's influenced not only oceanic conditions, the, the swells |
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| 01:09 | the margin, but also by the winds. And I want to bring |
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| 01:14 | back to the northern Bahamas and talk what happens once you get away from |
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| 01:19 | margin of the northern Bahamas that are by tidal currents and talk about the |
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| 01:24 | and products that occur more inboard. , we're gonna talk about the nature |
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| 01:29 | the platform interior first for great bahama . And then we'll continue to go |
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| 01:36 | back on the platform and talk about other style of carbonate deposition is common |
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| 01:42 | the rock record, which is tidal . So, you appreciate the, |
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| 01:46 | the tidal flats are put together for great bahama bank. These are famous |
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| 01:51 | flats that have been well published and in the literature for decades. And |
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| 01:58 | sort of controls are thinking about where should expect to find comparable deposits in |
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| 02:05 | rock record. But then I'll take back to keiko's and I'll show you |
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| 02:09 | way to make tidal flats. It's little bit different. And it obviously |
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| 02:13 | back to the trade wind models that talked about before. Okay, so |
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| 02:20 | back to this diagram, we talked the nature of the uh platform margin |
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| 02:29 | on the, on the northern Most of the northern Bahamas is dominated |
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| 02:34 | non scalable grain deposition involving either words political fabric. And we talked about |
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| 02:42 | models for making new IDs. And you get away from the high energy |
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| 02:47 | of the politics and environment, you into a broad area of low energy |
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| 02:53 | water where you accumulate a lot more mud and that lime mud is borrowed |
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| 03:00 | converted to fecal pellets. Okay, we use the term pill Lloyd in |
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| 03:06 | rock record for that kind of So, I'm gonna be using the |
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| 03:08 | colloidal sand or mud to characterize that . And you can see on this |
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| 03:14 | here that once you get behind the part of the analytics sand environment, |
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| 03:20 | get into the two belts, more belt that we call pellet sand. |
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| 03:26 | these are principally fecal pellets produced by burrowing shrimp by worms by mollusk, |
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| 03:32 | mixed with uh skeletal material that's adapted a little bit more restricted environment because |
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| 03:39 | circulation is more sluggish and the salinity a little bit more elevated. And |
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| 03:47 | call it a pellet sand or hard sand because most of the fecal pellets |
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| 03:53 | interstitial cemented on the sea floor, they're deposited by mechanism. We don't |
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| 03:59 | . Okay. But we observe and observe it not just in the |
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| 04:03 | but we see this in the rock as well. Okay. And so |
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| 04:09 | if you take a fecal pellet when comes out of the organism, you |
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| 04:12 | squish it back into the component lime , right? It's very easy to |
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| 04:17 | it back to the lime mud but some time period after being deposited on |
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| 04:22 | sea floor, something happens internally in fecal pellets and they become interstitial e |
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| 04:29 | . Alright. I mean by very my critics event we can't see the |
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| 04:33 | really. And but these fecal pellets so hard. If you put it |
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| 04:37 | your fingers, you can't break them like you couldn't break a piece of |
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| 04:41 | . Okay. And so you can that kind of fecal pellet is gonna |
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| 04:45 | well preserved in the rock record when bury it. It's not going to |
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| 04:49 | , you're gonna see a very distinct fabric preserved. Okay, now in |
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| 04:55 | Palestinian environment, that doesn't mean every pellet gets interstitial e cemented, it's |
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| 05:01 | a high proportion of them do. , So it's going to be a |
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| 05:04 | of soft and hard and fecal pellets it produces a distinct sand fabric and |
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| 05:13 | mud present alright because organisms need But to make fecal pellets. So |
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| 05:18 | the rock record, the pellets and is going to be preserved as a |
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| 05:22 | political act step. Alright, Brain but with some mud. All |
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| 05:29 | And then you see the green belt the headboard side of this diagram is |
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| 05:35 | colored mud. And that's because most the fecal pellets are not interested really |
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| 05:42 | . There's no difference in the fauna these two environments. Alright. And |
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| 05:47 | only, the only thing is in pellet mud environment. Most of the |
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| 05:50 | pellets don't get interstitial e cemented. we suspect that what we're seeing here |
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| 05:56 | a circulation effect. Right? As go further further up on a carbonate |
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| 06:01 | , your title current exchange, becomes sluggish. Your salinity increases a little |
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| 06:09 | . And we suspect that that that that you see on this map which |
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| 06:14 | consistent on a lot of these carbonate today, is due to circulation |
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| 06:19 | Alright. Some sort of subtle circulation . But we don't know for |
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| 06:24 | but we don't really know what's causing interstitial sanitation. But we make that |
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| 06:30 | that there is a textural change. , so the more seaward, more |
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| 06:35 | part of this broad area of lime deposition is always characterized by a more |
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| 06:41 | fecal pellet or colloidal sand. The part more of the softer fecal pellet |
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| 06:47 | , it's going to be preserved in rock record is sort of a vague |
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| 06:50 | wacky stone tax stone texture. so here's the map for the northern |
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| 06:58 | , that shows you the distribution of of these sediments. And Yeah, |
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| 07:03 | , we published this paper, we the different terminology for this political |
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| 07:09 | But basically the purple here are the little lime sands. What I just |
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| 07:16 | about that occurred and the more open of the platform. So the purple |
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| 07:22 | dominates these these platforms. Okay. you can see once you get behind |
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| 07:29 | margin with the coral sand and behind margin with the analytics and you get |
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| 07:33 | these broad areas of line mud deposition are being burrowed. But then with |
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| 07:39 | proportion of these fecal pellets being hardened the sea floor. Okay, and |
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| 07:44 | look at the orange here, The is really only occurring where you have |
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| 07:52 | afforded by this high pleistocene topography. , so Andrew's island is a high |
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| 07:58 | in Ireland and not that high. mean, maybe 40 50 60 ft |
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| 08:04 | sea level. A Luther I told over here is 200 ft above sea |
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| 08:08 | . But you can see, I you can see the story here if |
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| 08:11 | factor in the setting that we're in general easterly trade wind belt. |
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| 08:17 | where's this lime mud being deposited? where is it more restricted? It's |
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| 08:22 | the paleo topography. Right, So islands are acting like energy shadows to |
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| 08:28 | you to accumulate the lime mud and you're more inboard on the platform. |
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| 08:34 | is where you get a greater proportion these softer fecal pellets. Okay, |
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| 08:38 | why we think everything's tied back to . Alright. I'm gonna show you |
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| 08:43 | in this discussion that the more open of these platforms, shown by the |
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| 08:49 | are subjected to these weak cross bank that are set up by the general |
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| 08:55 | trade winds. And they went all some of the lime mud and they |
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| 09:01 | move stuff from the inner part of platform over the edge on the leeward |
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| 09:06 | . This is another part of the . We're gonna develop here in a |
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| 09:10 | . Okay, everybody appreciate what I'm here. So there are always these |
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| 09:14 | belts that occur on this kind of . That is where the energy is |
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| 09:19 | just on the margin. Alright, it's tidal currents that dominate most of |
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| 09:24 | platform. The only reefs we have the great bahama bank are over here |
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| 09:30 | of this side of Andros Island because catch the swells that come in through |
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| 09:34 | north east providence channel or we have that develop on the outer parts of |
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| 09:39 | islands that face directly into the atlantic . All right, so the rest |
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| 09:44 | this platform is all dominated by tidal . Again, tidal currents are only |
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| 09:48 | right on the margin. Okay, this means the rest of the platform |
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| 09:54 | is quiet water. Little energy Okay, so when you look at |
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| 10:01 | organisms, you look at the there's really no difference between between these |
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| 10:08 | . The hard colored sand environment has cover of sea grass. It's got |
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| 10:15 | producing calculus allergy that we talked about first day. Those little things that |
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| 10:20 | like the shaving brush. Uh It's debated by the burrowing shrimp, |
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| 10:27 | worms. The typical borrowers that we . Uh there's a restricted fauna here |
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| 10:34 | there's not a lot of good circulation . So just a few species of |
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| 10:39 | species of benthic foraminifera. Okay. essentially no difference between that and the |
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| 10:48 | palate environment. Alright, so it's the heart fecal pellet has nothing to |
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| 10:54 | with the organisms per se. so if you go to the inner |
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| 11:00 | of the great bahama bank, there's island that I showed you on the |
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| 11:05 | . This is looking to the Okay. And remember I think I |
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| 11:11 | you the slide our first day when talked about the origin of lime |
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| 11:15 | Right? These are the whiting's that talked about the stirred up bottom |
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| 11:20 | right? That some people think is of instantaneous precipitation. But I gave |
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| 11:27 | my feeling that most of this is just stirred up bottom mud by fish |
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| 11:32 | feed on the sea floor. so, you know, you're in |
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| 11:35 | quiet muddy environment and when you look , both of these environments, whether |
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| 11:41 | a hard fecal pellets or the soft pellet environments that both of them look |
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| 11:46 | this underwater. Okay, This topography see here is biologically created topography related |
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| 11:54 | to the burrowing shrimp. Alright, I showed you those little shrimp are |
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| 11:58 | this big and they have the ability burrow meters below the sediment water |
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| 12:06 | Okay, now, here the sediment never gets more than about two or |
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| 12:12 | m, so they can only go two or three m before they hit |
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| 12:16 | places in bedrock. But there are settings in the world of classics where |
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| 12:22 | shrimp will go down eight m below sediment water interface. All right. |
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| 12:27 | nothing to stop other than hard Okay. And so I told you |
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| 12:33 | they will go down, they'll put vertical chambers and put outside chambers. |
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| 12:38 | go down to another level to put chambers. All right. And the |
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| 12:42 | they encounter or make fecal pellets from burrowing activity, they throw the lightweight |
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| 12:48 | pellets out the top to make the current. Now that you see |
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| 12:52 | the little volcano shaped fabric and down the depressions, down in the depressions |
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| 13:03 | where they have another enter into their structure where they bring water in. |
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| 13:09 | ? And they actually use their tails set up circulation. Right? And |
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| 13:15 | circulation in their in their burrow All right. And we know this |
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| 13:20 | all created by the shrimp because after this whole surface is as flat as |
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| 13:24 | table with a zillion holes on top it. All right. And then |
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| 13:29 | a week or two, it'll build back to this this kind of |
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| 13:33 | Okay? So this is what the do, right? And you can |
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| 13:36 | what what they're doing to the sedimentary here. The first thing they're doing |
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| 13:40 | they're destroying any primary stratification that may been laid down by a storm. |
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| 13:47 | , Because this is not actively so there's no primary stratification related to |
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| 13:52 | or anything like that. The only would be related to a big |
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| 13:57 | but they're going to destroy that. . And secondly, they're going to |
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| 14:03 | the texture of the sediment. They're to take this mud size material and |
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| 14:08 | going to convert it to these fecal that you see here in thin |
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| 14:13 | Alright. Typical avoid to lift saddle fecal pellets. But again, in |
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| 14:18 | rock record, we're going to use term p Lloyd for this fabric. |
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| 14:23 | we see those unique internal striations of favorite vehicle pellet. And then what's |
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| 14:29 | third thing they do? Well, they destroy the organic material. |
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| 14:33 | so we're gonna talk about carbonate source next weekend. You'll see that as |
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| 14:39 | as you get any by observation superimposed a carbonate settlement or rock. The |
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| 14:45 | . O. C. Drops to , basically. Okay, they're either |
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| 14:50 | it or they're bringing oxygenated water into to oxidize that organic material. |
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| 14:58 | And then the other part of the that occurs back in this in |
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| 15:02 | Part of the those platforms like great Bank is that we have these uh |
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| 15:11 | features that that my colleague Harold Wanless called tubular tempest tights. The term |
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| 15:16 | tight is a german term for a deposit. And I'm going to show |
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| 15:22 | some temple sites that they're talking about this afternoon. But please, we've |
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| 15:32 | this term here for a situation that back in the inner part of this |
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| 15:37 | . We have this interplay between bio and hurricane activity. Right? So |
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| 15:44 | can see panel A is sort of typical story, right? These organisms |
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| 15:49 | down. They put out their side . I told you when they encounter |
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| 15:52 | coarser grain stuff, they don't try carry it out the top, They |
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| 15:56 | pack the side chambers, they throw lightweight fecal pellets at the top. |
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| 16:00 | then imagine what happens when a hurricane through hurricanes? Going to strip off |
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| 16:05 | burrow mound is going to create this of skeletal colloidal and mud material. |
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| 16:13 | what is it gonna do? It's backfill these borough structures. Right? |
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| 16:17 | going to create a fill that is different than the surrounding sediment, |
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| 16:23 | And you can easily recognize this in subsurface and core data, you'll see |
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| 16:27 | circular holes about the same diameter as shrimp burrows filled with this different |
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| 16:33 | Alright, these are what we call tubular tempest sites. Okay. And |
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| 16:42 | imagine as this process goes on right , you go back and forth between |
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| 16:46 | burrowing and the storm deposition. You see what you're doing through time. |
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| 16:51 | basically a modernizing this fabric. You're destroying the T. O. |
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| 16:57 | . And uh sometimes you don't see end up with, you know, |
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| 17:02 | few distinct boroughs actually preserved. But see no stratification. So, I |
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| 17:07 | I told you last week and if we don't see any stratification in |
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| 17:11 | rock, we assume it's been burrowed many times over. Okay. That's |
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| 17:17 | sort of the first principle of carbonate . Okay, everybody clear about |
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| 17:24 | So that dominates the inboard part. me. The great bahama bank. |
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| 17:32 | we come back to, that's a . When we come back to to |
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| 17:37 | platform, I'll show you there is little bit of that fabric that accumulates |
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| 17:41 | the inner part of keiko's platform, not to the same extent. I |
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| 17:45 | showed you. Yeah, I guess kind of unfair. Well, it |
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| 17:58 | blends everything together. It blends the sediment and the storm related sediment |
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| 18:04 | Okay. Whereas here, like in B you would have seen distinct differences |
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| 18:09 | the borough fill and the surrounding background , which would be that colloidal fabric |
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| 18:18 | . Yeah, that's all that's all made. So you'll see you'll |
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| 18:22 | I think you'll see some pictures of rock. Record what I what I |
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| 18:27 | by something like panel E later. . Alright, well, let's move |
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| 18:35 | and continue more inboard. If you more inboard on great bahama Bank, |
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| 18:42 | actually come up onto Andros Island that showed, You know where that |
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| 18:48 | right. Andros Island is the largest the Bahamian islands in the northern |
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| 18:53 | Ah It's famous for a lot of things. It's infamous for the drug |
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| 19:02 | that's occurred there for decades. In , the drug activity got so bad |
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| 19:08 | in the 80s that all the oil stopped going to Andrews to look at |
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| 19:12 | title flats because it's just too And that's actually what switched everything down |
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| 19:19 | keiko's to the keiko's tidal flats. going to talk about a little bit |
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| 19:24 | . Okay. Uh but it's also it or not, it's a big |
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| 19:29 | island, they grow a lot of of vegetables that get imported into south |
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| 19:35 | into the U. S. And never think that, but, but |
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| 19:39 | is. And so we're going to about Andrew's island. So, here's |
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| 19:45 | map again. Alright. So we've finished talking about the nature of this |
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| 19:50 | restricted, low energy, quiet water , interior styles of deposition. The |
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| 19:55 | and soft fecal pellets when you come on the western side of the andrews |
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| 20:02 | . This is where you plaster some that settlement up against that older landmass |
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| 20:08 | storm processes. Alright. So the title flat um for a lot of |
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| 20:17 | has this connotation that the tidal currents driving the deposition. Right? Whenever |
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| 20:24 | uses the term title, usually think tidal currents playing a role here. |
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| 20:29 | , that's a misnomer for almost all tidal flats. It's common in classics |
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| 20:35 | see tidal currents drive tidal flat but in carbonates we really should use |
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| 20:40 | term storm flat. Okay, because is driven by winter storms or the |
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| 20:47 | hurricane. Alright, so, I'm show you the nature of the andrews |
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| 20:53 | flats up here. Alright, remember . This is these are the larger |
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| 20:58 | were in a general easterly trade winds . So the tidal flats are on |
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| 21:03 | least side of this high pleistocene Um We're also in a rainier |
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| 21:11 | Alright. The northern Bahamas have no effectively associated with the shallow marine carbonate |
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| 21:20 | . Alright, and so I'm going show you the nature of these tidal |
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| 21:23 | first, then I'm gonna bring you to keiko's platform and I'll show you |
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| 21:29 | different style of title flat deposition, it also in a different climate. |
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| 21:34 | a semi arid climate here. I've told you there, evaporates here. |
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| 21:38 | think we talked about that last weekend we're talking about demonization. Okay, |
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| 21:44 | , again, just by going 400 miles further to the southeast, |
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| 21:50 | get into a situation where we're in windier climate and also drier climate compared |
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| 21:56 | Andrews and then later, when I into the carbon a ramp model, |
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| 22:02 | about tidal flats in abu Dhabi in Middle East. That will be the |
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| 22:06 | era tidal flats. And you'll see lot of evaporates associated with parts of |
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| 22:11 | tidal flat system. Okay, so just think about the lay of the |
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| 22:16 | here. Okay, I think, hope you're starting to get some sense |
|
| 22:19 | for the general fizzy graphic setting. have the we have the trade wind |
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| 22:25 | here, have a climatic over But what are the other two controls |
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| 22:30 | come into play here? Uh, are first of all winter storms. |
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| 22:36 | , so the cold fronts, they through the canal? Us right. |
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| 22:41 | got one coming in here, I later, tonight or tomorrow morning. |
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| 22:45 | front, right, that front's gonna on down to Miami and a lot |
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| 22:50 | times it's going to run offshore into northern Bahamas. Again, the strength |
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| 22:55 | that winter front cold front determines how down to the southeast it goes before |
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| 23:01 | dies out. Okay. But if look statistically every year, Andrews Island |
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| 23:09 | 40-60 winter storm effects. Okay. so when we think about the storm |
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| 23:16 | the start front comes like this, what are the first wins? The |
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| 23:20 | wins are the strong winds coming out the southeast, right, You always |
|
| 23:25 | the winds up from the southeast and the front comes through and the winds |
|
| 23:29 | . So where are the strong winds out of the northwest. Okay. |
|
| 23:33 | it's the northwest winds that would do would affect Andrews island. Right, |
|
| 23:38 | that island is facing to the west northwest. So it's a stronger cold |
|
| 23:44 | , northwest winds that drive deposition on tidal flats. And then what will |
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| 23:49 | to those winds that will swing around the north and then they'll come back |
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| 23:52 | to the northeast and then they'll come to the prevailing easterly. So, |
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| 23:58 | , so that's part of the story title fat deposition on andrews. And |
|
| 24:02 | the other part of the story is . All right. We're in the |
|
| 24:07 | of the world that hurricanes moved through area. Right. In fact, |
|
| 24:12 | area between Cuba and Great bahama This area right here is called Hurricane |
|
| 24:18 | because this is where a lot of major hurricanes shoot through. And |
|
| 24:24 | if you look at the statistical record the last almost 100 and 50 years |
|
| 24:29 | more, uh, Statistically Andrew sees hurricane every 7.5 years. Okay. |
|
| 24:37 | so we're going to talk about what due to tidal flats, but appreciate |
|
| 24:41 | . That's the case here. now keiko's being further south and closer |
|
| 24:46 | Hurricane Alley actually sees statistically a greater hurricane every 5.5 years. Okay. |
|
| 24:56 | you know, like I said, a different setting here. It's a |
|
| 24:59 | you're setting and it's also drier climate to. And so let's take a |
|
| 25:04 | and let me try to show you this this tidal flat system is put |
|
| 25:07 | . All right now, the whole whole point of these conversations here started |
|
| 25:13 | and carry on today, is to you to appreciate, you know, |
|
| 25:18 | these carbonate environments are put together. . But I also want you to |
|
| 25:22 | thinking about, you know, what some of the preserve about attributes that |
|
| 25:27 | carry through to the rock record? would allow me to interpret the platform |
|
| 25:32 | barrier reef or a platform margin sand or a widespread platform interior colloidal |
|
| 25:40 | stone or a tidal flat. so that's the concept of comparative climatology |
|
| 25:46 | we talked about yesterday. So, want you to be thinking about |
|
| 25:50 | but more specifically with respect to tidal . Why do we care about recognizing |
|
| 25:56 | flats? We care about it because a proxy for sea level. |
|
| 26:02 | You know, the carbonate realm is the Bay of Fundy where you have |
|
| 26:06 | 30 ft tidal range, right? m tidal range. Alright, macro |
|
| 26:12 | , right? These are micro 2 to 3 ft of title of |
|
| 26:17 | change level water level change every 12 . And so what that means is |
|
| 26:23 | tidal flat is basically accumulated right, or close to sea level. |
|
| 26:28 | So if you can recognize the title in the rock record, it helps |
|
| 26:31 | understand your overall vertical sequence. Because sometimes when we look at things |
|
| 26:38 | of context, we don't exactly know to place some of these environments. |
|
| 26:42 | ? Until we see the whole picture being able to pick out a tidal |
|
| 26:46 | or a beach, right? Beach be the same thing. Proxy for |
|
| 26:50 | level. That really helps. And then what happens when we pop |
|
| 26:56 | the sea level close to sea What did we talk about from the |
|
| 27:00 | genesis standpoint? We have the potential either be exposed to rainfall, |
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| 27:05 | But to start to create some die scenarios or in a drier climate, |
|
| 27:11 | wouldn't have rainfall, but we we have exposure to evaporating fluids. |
|
| 27:18 | we talked about how they could drive like demonization. Okay, so that's |
|
| 27:22 | other important consideration. Okay, so here's andrews tongue of the ocean, |
|
| 27:29 | is Nassau, This is the capital the Bahamas. And you can see |
|
| 27:36 | darker colored stuff here is all placing topography and all of this stuff on |
|
| 27:43 | back side is the modern, laid within the last few 1000 years of |
|
| 27:50 | flat deposition. Okay. And then right offshore is the shallow, soft |
|
| 27:56 | lime mud environment. I mean you know, just a couple of |
|
| 28:00 | of water down. It's very difficult get a boat in here and said |
|
| 28:04 | . Okay. And uh so let's talk about how this whole system was |
|
| 28:09 | together. All right. So, you look at a cross sectional view |
|
| 28:13 | what I just showed you the there's a high places in bedrock topography |
|
| 28:18 | Andrew's. Okay. These are essentially little grain stones, which is a |
|
| 28:23 | sort of sediment that we had back the Pleistocene for made up most of |
|
| 28:27 | islands. And then the title flat is shown in red here And you |
|
| 28:33 | see it's an awe flapping wedge, ? It basically pinches out up against |
|
| 28:39 | pleistocene bedrock topography and then it is to 4m sick at the seaward |
|
| 28:45 | Okay, and almost all of this , I would, I would never |
|
| 28:51 | all of it because there is some skeletal material that gets produced there. |
|
| 28:56 | almost all of that fabric is not locally produced is being produced offshore. |
|
| 29:02 | , the green area that you see this diagram is the area of mud |
|
| 29:07 | that gets burrowed and pellet ID, the source for most of the sediment |
|
| 29:11 | gets thrown up onto the table flat hurricanes or by occasional winter storms. |
|
| 29:21 | , Alright, everybody appreciate that. , most of the modern tidal |
|
| 29:29 | I'm gonna show you. Andrews, even the abu Dhabi example here are |
|
| 29:35 | MMA critic and colloidal because that's what's produced offshore. That does not mean |
|
| 29:42 | ancient title flat is going to be composition, it depends on what is |
|
| 29:48 | produced offshore. Okay, so sometimes tidal flats are grain stone. Excuse |
|
| 29:59 | if you if you're producing carbonate sand , right then your title flat is |
|
| 30:04 | to be the same composition carbonate And we have a couple examples of |
|
| 30:09 | today in the modern and we definitely examples of that in the rock |
|
| 30:14 | Okay, so, I don't want to come away from this discussion thinking |
|
| 30:17 | ancient carbonate tidal flats are the critic colloidal. Alright, I'd say most |
|
| 30:24 | , but not all. Okay, , so just make sure you appreciate |
|
| 30:29 | . Okay. And as I you know, we call these tidal |
|
| 30:33 | , but really we should call these flats. And if you have more |
|
| 30:38 | a classic background, um I think good way to look at a carbonate |
|
| 30:44 | flat or storm flat is to uh at it like it's a delta turned |
|
| 30:53 | out. Okay, so, you , river delta, like, like |
|
| 30:57 | Mississippi delta. Right? The sediments being being pushed from land offshore. |
|
| 31:03 | ? You get over bank deposition on levees. Okay, you feed stuff |
|
| 31:08 | into a little bit deeper water. look at it the other way around |
|
| 31:12 | , Right? The sediment is coming offshore. It's being fed, pushed |
|
| 31:17 | these distributor very channels with over bank . That's what produces the levees. |
|
| 31:23 | , so it's like a classic delta inside out. Okay. And you |
|
| 31:29 | see there are three parts to this here. The first part is the |
|
| 31:34 | marine and we link it to the flat because that's the source of the |
|
| 31:39 | . And then the second part is we call the Channel belt. |
|
| 31:45 | Those are the title channels that cut bedrock. So bedrock is up to |
|
| 31:50 | below the water level. All That doesn't mean all, all the |
|
| 31:56 | are four m, but that's as as they can go. Right, |
|
| 32:00 | can only hit down to bedrock and can see that they dissipate as you |
|
| 32:05 | further onto the title flat. They die out. And you can see |
|
| 32:10 | levees are better developed on the seaward because that's where during a winter storm |
|
| 32:16 | push a wall of water up on tidal flat and you overflow or get |
|
| 32:21 | bank deposition on the levee. And that's as far as you go |
|
| 32:27 | the winter storm cannot push sediment this back into the, into the so |
|
| 32:31 | pond. Okay, so the channel and pond complex here is the second |
|
| 32:37 | . Alright, The ponds are underwater the time. The levees are high |
|
| 32:41 | dry during normal high tide. They're covered by water when the storms push |
|
| 32:47 | wall of water over the levee. . And then the third part would |
|
| 32:52 | the inla naga martian green here. marshes colonized by continuous maths of black |
|
| 33:00 | and uh they're back there because it's restricted there. The only thing that |
|
| 33:06 | live their rights to restricted for It's too restrictive for scalable producing |
|
| 33:12 | Okay. And the only time you sentiment back in the pond or into |
|
| 33:18 | marsh would be with hurricanes. so winter storms focus their deposition along |
|
| 33:23 | seaward edge of the channel belt. can lay sediment down anywhere across this |
|
| 33:32 | . Okay, so on a clear , on a normal day where there's |
|
| 33:38 | no winter storm, the offshore marine water is crystal clear. All |
|
| 33:44 | It carries no sentiment. But when winter storm front comes through, this |
|
| 33:49 | what happens offshore. You can see water, it becomes cloudy. You've |
|
| 33:55 | it with both nick, right? fecal pellets. And actually some of |
|
| 33:59 | lightweight things like benthic foraminifera, those those little multi chambered benthic foraminifera that |
|
| 34:06 | a couple of millimeters in size. actually can be easily put in |
|
| 34:11 | And then that stuff is delivered onto title flat. Okay, so this |
|
| 34:15 | the condition you need to move sediment the offshore subtitle up onto the channel |
|
| 34:22 | in that title. Flat complex. ? As I said, this will |
|
| 34:26 | 40-60 times uh during the winter. . Nothing like this happens in the |
|
| 34:33 | . There's no winter storm of Alright. Hurricane obviously would do the |
|
| 34:37 | thing, but to to a greater . Okay, so another view just |
|
| 34:43 | give you the three belts and I'm . Alright, you already know what |
|
| 34:46 | offshore marine environment looks like. It's got a restricted fauna. Its |
|
| 34:51 | baited by the shrimp. You're producing of fecal pellets in the inner part |
|
| 34:57 | the platform. Most of these are fecal pellets. And then here's the |
|
| 35:01 | belt and you can see how the just die out into the inland algo |
|
| 35:06 | . And then the high prices in occurs back here. So all this |
|
| 35:11 | fabric you see here and you see little bit of it out here on |
|
| 35:14 | channel belt. All of this dark here is related to the continuous mats |
|
| 35:21 | cyanobacteria. Okay, okay, so appreciate what I'm saying here. |
|
| 35:29 | The sediments coming from offshore is being up onto the complex. The winter |
|
| 35:33 | lay down most of the deposition along levees. The levees eventually die out |
|
| 35:38 | the ponds. The ponds are relatively . Alright, in Nago marsh and |
|
| 35:45 | pond only sees sedimentation during the hurricane not because of the winter storm |
|
| 35:51 | All right. And then you notice the map is showing these little gray |
|
| 35:56 | here. The gray patches. Are proto dolomite press that we talked about |
|
| 36:02 | weekend. Number one of the models um evaporative pumping model. We pull |
|
| 36:09 | up from the underlying marine water table a tidal flat and you precipitate out |
|
| 36:14 | dolomite as a cement. All so that's the patchy crest development that |
|
| 36:21 | some of it on the levees. of it occurs in the marsh |
|
| 36:27 | Okay, so let's take a closer at this fabric here. Let me |
|
| 36:32 | you a feel for what are the between these sub environments? Right. |
|
| 36:37 | , what what do we see on levee? What do we see on |
|
| 36:41 | back slope of the levee? what do we see in the |
|
| 36:45 | And then what does the inland algo look like? Okay. Again, |
|
| 36:50 | thinking about, you know, I'm to recognize an ancient title flat and |
|
| 36:53 | punched a core hole into that ancient flag. What would I expect to |
|
| 36:58 | depending on where I punched the hole the map like this. Okay, |
|
| 37:07 | , we're gonna start with the channel here. We're gonna we're gonna talk |
|
| 37:10 | the levee deposits, which are the features you see here on the |
|
| 37:16 | Right? So this is elevated levy to over bank deposition every time you |
|
| 37:21 | winter storm forcing water in onto this . During a normal tidal cycle, |
|
| 37:28 | levee sits high and dry. It's out of water. Okay. And |
|
| 37:32 | , so basically, this is super in terms of where it fits into |
|
| 37:36 | title cycle of water level and then slope down the back here. This |
|
| 37:42 | essentially the upper intertidal zone. That's black cyanobacteria mat. Get too restrictive |
|
| 37:49 | anything to live there other than the . no borrowing no skeletal producing |
|
| 37:55 | And then you drop down into the inter title and subtitle. Well, |
|
| 38:00 | the pond. Okay. All of lighter stuff is the pond. And |
|
| 38:04 | it's more brownish color. That's more the lower intertidal zone with scrub mangrove |
|
| 38:10 | because the mangroves like to live in sort of inter title zone and then |
|
| 38:15 | wider, deeper part of the And by deeper, we're talking, |
|
| 38:19 | know, maybe four or 5 ft water depth at the most. That's |
|
| 38:24 | lighter color stuff here, because there's mangroves, right? They don't live |
|
| 38:28 | a true subtitle environment. They like be in that inter title zone. |
|
| 38:32 | . And then back here is the inland algo marsh here colonized by the |
|
| 38:37 | cyanobacteria that occur on the back slopes these levees. Okay, so here's |
|
| 38:44 | cross sectional view of the transition from title channel, Which can be up |
|
| 38:49 | four m deep if it cuts to . The levee, the back slope |
|
| 38:54 | the levee, which is not shown is the pond off to the right |
|
| 38:59 | high tide, right? Mean low . That's a 2-3 foot difference in |
|
| 39:07 | . And notice that the levy is up above the high tide. |
|
| 39:13 | And so the only time it sees is during the winter storm or hurricane |
|
| 39:18 | you push a wall of water onto tidal flat and you get over bank |
|
| 39:23 | focused on the levee. Okay. so you remember in the air photograph |
|
| 39:28 | was a lighter color, it's lighter because it's colonized after deposition, it |
|
| 39:34 | quickly colonized by quickly. I mean a day or two it gets quickly |
|
| 39:39 | by a sign of bacteria called So is a thin little living green |
|
| 39:50 | . That makes it very, very . Right? But you can see |
|
| 39:54 | color in the sediment. All When it gets covered with sediment by |
|
| 39:59 | few millimeters of sediment, which is gets laid down by a winter |
|
| 40:03 | It does not die. It extends filaments up through the sediment and |
|
| 40:09 | Is that surface? Okay, so schizophrenics is there because it's adaptable. |
|
| 40:14 | sediment stress. All right. And you saw in the air photograph but |
|
| 40:19 | to the black zone behind it. , that's a different kind of |
|
| 40:24 | Alright. And you know, we should change this. We shouldn't call |
|
| 40:30 | algal anymore. It's called cyanobacteria. right. But essentially what we used |
|
| 40:36 | call blue green algae, uh cinema a different morphology. It says has |
|
| 40:45 | spongy texture. It looks like a map. You can sort of see |
|
| 40:50 | prismatic tufted spongy like fabric. if you put a millimeter sediment on |
|
| 40:57 | of Saida Neema, it dies. , it can adapt to that sediment |
|
| 41:04 | and we know this because my colleague is modern monitor, these tidal flats |
|
| 41:11 | down di layers and things like that record these storm events and to see |
|
| 41:15 | happens to this fabric and and literally dies and it takes about two years |
|
| 41:21 | it comes back. Okay, So old literature says that the the distribution |
|
| 41:30 | the schism tricks and cinema are controlled elevation. The was adapted to a |
|
| 41:39 | elevation and cited Neema was a lower . It's just the opposite it's sediment |
|
| 41:45 | . Okay, The Levy is your of sediment stress, right? Every |
|
| 41:50 | storm. This is where you focus or two of overbanked opposition. It |
|
| 41:57 | out before it gets back here. . And that's why I said the |
|
| 42:00 | is there. But if it gets over by a bigger winter storm or |
|
| 42:04 | hurricane dies. Okay. Alright. , let's take a look. All |
|
| 42:09 | , And we'll start correct. Let's a look. We'll start with the |
|
| 42:15 | the white super title level here. , You can see one of the |
|
| 42:19 | title channels here side distribute terry All right. We'll start with the |
|
| 42:25 | fabric here and white. Then we'll about the side of the mats on |
|
| 42:29 | back slope. And then we'll finish by talking about the the borough subtitle |
|
| 42:35 | pond. All right. So, in a boat and one of those |
|
| 42:41 | title channels looking up onto the This photograph was taken at mean high |
|
| 42:48 | . Alright, So that's the that's upper normal high tide level. So |
|
| 42:52 | can see how much sediment we produced , that's over a meter of vertical |
|
| 42:58 | . All right above being high all of this laid down by winter |
|
| 43:03 | and the occasional hurricane, you can where the last over bank event related |
|
| 43:09 | winter storm was in the trees here the debris line. Alright. And |
|
| 43:16 | first thing you notice about these sediments because they're above sea level, they're |
|
| 43:21 | colored, right? They have this tan color. Alright. And if |
|
| 43:27 | were to see the sediments below they don't have a gray color. |
|
| 43:32 | ? When you're underwater, everything's reduced least on the surface. Okay, |
|
| 43:36 | it has a great color but above level everything is oxidized, lighter |
|
| 43:45 | So the color I think is unique the levy, right? Because you're |
|
| 43:50 | the stuff above sea level. And notice that there's by observation here. |
|
| 43:57 | can see all of these holes These holes are created by crabs. |
|
| 44:02 | , so little fiddler crabs, little crabs, Little things are about this |
|
| 44:06 | right? They burrow into the sediment their burrow network will go down to |
|
| 44:10 | water. They have to be linked the water. Okay. But they |
|
| 44:15 | live or occupy some of these burrow about that mean high tide level. |
|
| 44:20 | , So that appreciate that there is degree of bio probation, even in |
|
| 44:25 | levee. Alright. But if you a chunk of that surface levy |
|
| 44:29 | look at it like we've done you can see right at the |
|
| 44:34 | you see a layering preserves. That's classical millimeter scale stratification. I'm sure |
|
| 44:41 | can't see this, but I certainly see with that. But maybe in |
|
| 44:46 | computer you can see there's a little green rind right at the top of |
|
| 44:51 | surface. That's the living schizophrenics. , that's the scale of the schism |
|
| 44:57 | . Alright, and again, what this fabric being produced by? It's |
|
| 45:01 | produced by schizophrenics grows right, colonize surface actually creates a dense leathery |
|
| 45:10 | It's actually hard to physically rip Okay, so it really does provide |
|
| 45:15 | to that surface. Then it gets by a couple of millimeters of |
|
| 45:19 | But they re extend and recolonize. keep doing this through time. |
|
| 45:24 | When you produce this classical millimeter scale but it has, its not |
|
| 45:31 | it goes like this, right? sort of bumpy up and down because |
|
| 45:35 | the growth form of the santa So the term we use to characterize |
|
| 45:40 | is crinkly crypt algal lamination. so this is one of the characteristics |
|
| 45:48 | levees. This is exactly one of things people would look for in the |
|
| 45:51 | record to say. Yeah, I into part of a tidal flat |
|
| 45:56 | Okay, the light color. The crypto Gle fabric. Okay, lack |
|
| 46:05 | bio probation. Right at the surface part of it has to do with |
|
| 46:10 | fact that the matter is so The burrows couldn't break through that very |
|
| 46:14 | anyway. Okay, so so you some of that stratification and when you |
|
| 46:20 | at this event section, it's actually layers you see there are made up |
|
| 46:26 | three parts. The first part, it or not, is the muddy |
|
| 46:31 | here. So when the storm starts you put mud and suspension, the |
|
| 46:37 | thing that happens is the cyanobacteria actually the mic, right? They put |
|
| 46:41 | a mud layer on top of Okay, and then what comes in |
|
| 46:45 | top of that is the bed load , which is the ploy. It'll |
|
| 46:50 | . So you see the plight of here. So this is essentially a |
|
| 46:54 | ploy to brain stone that gets laid on top of that. And then |
|
| 46:59 | storm subsides. So what happens? settle out mud from that murky water |
|
| 47:05 | that's what's on top. Okay, you go from a mud layer to |
|
| 47:09 | little grain stone layer to mud layer that makes up one of the crypto |
|
| 47:13 | lamination. Okay, I really appreciate . Alright, that's what winter storms |
|
| 47:20 | millimeter scale stratification. All right. then here's another core through the |
|
| 47:27 | You see that that crypt of a going through here. But then you |
|
| 47:32 | these funny shaped holes. Those holes the financial porosity we talked about last |
|
| 47:39 | . Okay, remember the origin of process, its primary poor type too |
|
| 47:46 | to be explained by the packing of grain. Something held it open at |
|
| 47:49 | time of deposition. And so how it being created on a tidal flat |
|
| 47:55 | shallow burial? The cyanobacteria will eventually and they will start to disintegrate and |
|
| 48:03 | give off carbon dioxide or H two or methane and that gas will try |
|
| 48:10 | escape and some of it will But some of it gets trapped in |
|
| 48:14 | sediment to create that funny shape So that's fine astral prostate. And |
|
| 48:20 | see how it sort of tracks that algal fabric. Right? So I |
|
| 48:25 | say this is the second most common people would want to see in the |
|
| 48:28 | record. Right? The finesse troll associated with this MMA critic. So |
|
| 48:34 | right, you can't do this Okay. And where was the other |
|
| 48:40 | where we make financial processes? The environment, but this is not a |
|
| 48:44 | , right? Because clearly this is is low energy and the critic |
|
| 48:48 | This is the levee. Right. then if you look at the surface |
|
| 48:52 | the levee, what happens during the when you don't have frequent wedding of |
|
| 48:58 | levy by overbanked deposition, you get of Warmer, hotter weather, |
|
| 49:06 | I mean get up to the 90s the, in the summer and what |
|
| 49:12 | you get? You get desiccation, , mud cracks. So I would |
|
| 49:18 | , you know, people want to mud cracks in the rock record to |
|
| 49:20 | with the title flat. Again, can never do this underwater. And |
|
| 49:26 | what will the hurricane do that comes in the summer or the fall? |
|
| 49:31 | . It can rip up some of mud crack fabric and create this fabric |
|
| 49:35 | we called an inter class last Okay, remember that type of composite |
|
| 49:43 | ? These play T fabrics ripped up by hurricanes transported to a few feet |
|
| 49:50 | of feet. Okay, so that's that's another fabric that people want to |
|
| 49:55 | in in the rock record. Alright. So everybody appreciate what I've |
|
| 50:01 | . So all the classical fabrics that want to see in the rock record |
|
| 50:06 | only associated with the areas of white deposition on this photograph. Well, |
|
| 50:12 | much of the area is dominated by ? Not a whole lot. |
|
| 50:17 | So, you know, you'd have be pretty fortuitous to drill into something |
|
| 50:22 | this to to see a lot of classical fabric. So it's a bit |
|
| 50:26 | a challenge. Okay. All So let's talk about the back slope |
|
| 50:30 | . You see when we come off levee and you slope down into the |
|
| 50:34 | that roughly upbringing title zone here is black zone dominated by cinema. |
|
| 50:41 | it has a texture of a Alright, this is what it looks |
|
| 50:46 | . And again, it makes these mats and uh too restricted in the |
|
| 50:54 | intertidal zone to be burrowed or to any living institute scalable material. So |
|
| 51:01 | their world. They take over. . And uh and but they don't |
|
| 51:06 | they're on the back slope because they're by the levee from overbanked deposition because |
|
| 51:14 | I said, they don't want to covered by sediment. Okay. And |
|
| 51:19 | it's generally in the in this area the back slope of the levee where |
|
| 51:26 | get the side of the mats or you'll see for the L. |
|
| 51:29 | Na go marsh. This is the where you tend to get a little |
|
| 51:31 | more of this crest development. We about uh last saturday, right. |
|
| 51:37 | we're talking about demonization, these crusts very patchy laterally and they're also Apache |
|
| 51:44 | . Right? If your decor or through the sediment, it's not you |
|
| 51:48 | get these continuous layers of the crust very patchy and distribution. Alright. |
|
| 51:55 | the downside of this fabric is that not replaced. I said the |
|
| 52:01 | the cement filling some of that process with that political grain stone material has |
|
| 52:09 | thrown back into this part of the flat and then you come into the |
|
| 52:14 | and by definition the pond is subtitle the shallow part of the pond, |
|
| 52:21 | the Lerner title. The subtitle part the pond is where you get the |
|
| 52:27 | and these are scrub mangroves. They're very tall in the Caribbean, they |
|
| 52:32 | get very tall because they get blasted by hurricanes. But you know, |
|
| 52:37 | mangroves actually get up to, they grow to heights of 60 or 80 |
|
| 52:41 | if they don't get blasted by a . And but here they're all scrub |
|
| 52:47 | . And and there there are two types here. They're they're what we |
|
| 52:50 | black and red mangroves. The red have these proper roots that you see |
|
| 52:57 | , that sort of stick up above water level. And the role of |
|
| 53:05 | again is to it's the, well a stabilizer for shore line. |
|
| 53:11 | That's the good news. They helped some of the shorelines, but but |
|
| 53:15 | a sedimentary, the structure standpoint, actually can destroy primary sedimentary structures from |
|
| 53:23 | routing their roots can go down again below the surface and effectively biter bait |
|
| 53:31 | sediment. So they play a role like the growing organisms. They play |
|
| 53:35 | role in modifying their biter baiting the . Okay, so once you go |
|
| 53:41 | in the pond, well, now into a definition of marine environment, |
|
| 53:46 | it's not an open marine environment where have good exchange of water, you |
|
| 53:50 | have normal salinity. I mean, walk back to the walk in these |
|
| 53:55 | in the summer, it's really the is really hot and the salinity is |
|
| 54:01 | a little bit. So you just a few species of mollusks get a |
|
| 54:05 | species of benthic foraminifera, but you see one of the mollusk. Is |
|
| 54:11 | these that's present here are these tiny gastro pods? They're about this |
|
| 54:17 | Okay. And what's the role of gastro pods? Again? They eat |
|
| 54:23 | bacteria, right? They eat the of the ocean essentially. That's what |
|
| 54:28 | eat. And that's why you get color change you saw in the |
|
| 54:32 | right? The black kind of bacteria stops, right when you get to |
|
| 54:36 | pond, it's not that they don't to live in water. They can |
|
| 54:41 | in water. Okay. They can underwater but they can't survive because they |
|
| 54:46 | eat. Alright, so these little pods effectively keep the cyanobacteria from uh |
|
| 54:54 | into that marine environment. Okay. you can see one of the roots |
|
| 54:59 | of the mangrove. Okay, so soon as you go underwater you pick |
|
| 55:04 | a skull of fauna, but it's . You limit the incursion of the |
|
| 55:09 | bacteria and you have the return now the burrowing organisms of the shrimp and |
|
| 55:15 | worms and molluscs now come into play . So the next photograph is a |
|
| 55:21 | cast of of some of the borough to give you a feel for how |
|
| 55:28 | these shrimp are in modifying the So What they did here was they |
|
| 55:35 | a 20 gallon barrel of epoxy Okay. And they added the hardener |
|
| 55:42 | they mixed it up and they poured down one burrow hole. Okay. |
|
| 55:47 | then they waited an hour or two it to harden up and then this |
|
| 55:51 | what they dug up. Okay, is probably not one borough structure. |
|
| 55:56 | is probably a number of shared burrow . You can see this from these |
|
| 56:03 | , you can see the bird, borough is typically don't change the diameter |
|
| 56:08 | their whole, okay, except where come up against each other. Then |
|
| 56:14 | do this, they narrow down, , they don't close off but they |
|
| 56:21 | the diameter of their connection with with their buddy. Okay. And |
|
| 56:26 | do this for two reasons. The reason is they want to share |
|
| 56:30 | The second reason is they don't want buddy to come in and steal their |
|
| 56:33 | light. Okay, remember that You guys are probably too young for |
|
| 56:41 | , jeez uh there's an old tv or bud light, you know, |
|
| 56:47 | light. Right? So we're talking these new york complexes right? Where |
|
| 56:52 | guy would open his refrigerator and the york apartment share circulation, right? |
|
| 57:00 | Well, they'd have a guy on other side of the other apartment next |
|
| 57:03 | reaching into that guy's refrigerator, steal bud light. Right, So that's |
|
| 57:08 | concept here, Right? The shrimp to share the circulation but they don't |
|
| 57:12 | one shrimp to come into their complex steal their food. They actually grow |
|
| 57:18 | , believe it or not, They diatoms and stuff like that on the |
|
| 57:21 | of their their their burrow structure, Okay, so, but I think |
|
| 57:29 | can see right how important this process to modify the the sedimentary record, |
|
| 57:36 | ? Wherever you get by on remember the shrimp have been around going |
|
| 57:40 | to the order vision. Okay. so they've been doing this for a |
|
| 57:45 | time, right, destroying stratification, texture, eating organic material. |
|
| 57:52 | so everybody appreciate what I've said So we've just talked about the channel |
|
| 57:59 | . Right. And the variations um theme for the sedimentary structures, |
|
| 58:04 | Look at the pond here, restricted subtitle burrowed looks very similar in |
|
| 58:11 | of fabric to what's being produced offshore, correct? Alright. Didn't |
|
| 58:15 | show you the same kind of thing offshore, restricted fauna? By by |
|
| 58:21 | . So, I think you could a problem here, right, in |
|
| 58:25 | rock record, right? You could into part of a tidal flat |
|
| 58:29 | but hit the pond. It looks lot like the stuff that's offshore and |
|
| 58:34 | would probably never know you're in a flat. Okay, and so there's |
|
| 58:38 | term that has evolved in the literature people that encounter these more restricted subtitle |
|
| 58:47 | like the pond or the shallow marine of a tidal flat. And the |
|
| 58:52 | is perry title pe ri title. word. Alright, very title. |
|
| 58:59 | this is like, this is a to convey uncertainty about the setting, |
|
| 59:06 | ? I know I'm in a restricted environment, but I don't know if |
|
| 59:10 | in a offshore platform interior setting or I'm part of a tidal flat. |
|
| 59:16 | , so perry title gets used a in the literature where people try to |
|
| 59:22 | their uncertainty about their their setting. , so you should be familiar with |
|
| 59:27 | term. Okay. Alright. And the last part of the story here |
|
| 59:32 | the is the marsh that occurs in uh the inner part of the title |
|
| 59:39 | again, I told you the only to get settlement back here and that |
|
| 59:43 | continuous blackout cyanobacteria mat zone is by . Okay, so for long periods |
|
| 59:51 | santa bacteria in lago marsh sits high dry. Right? It doesn't get |
|
| 59:58 | by day to day title exchange, only gets covered by water pushed back |
|
| 60:02 | by hurricanes. And so you can there's a lot more sanitation effect here |
|
| 60:08 | you get these more continuous crest of dolomite and other arrogant knight and heimat |
|
| 60:14 | cements. And unfortunately this is this the fabric that chased this is the |
|
| 60:23 | that invited the druggies in. This what they try to land their planes |
|
| 60:27 | to offload the drugs. Okay, can land ADC three on the |
|
| 60:32 | they can land a twin engine for engine plane. Alright? And when |
|
| 60:37 | you fly over parts of the title , you'll see where some of the |
|
| 60:44 | planes miss there. They hit the , right with the mud and they |
|
| 60:51 | the landing down here. So, this is this is what chased all |
|
| 60:55 | companies away from working on. We to fly, we used to people |
|
| 61:01 | to go in by boats first and it became too dangerous for that. |
|
| 61:04 | then we started, most of the companies started chartering seaplanes out of |
|
| 61:09 | but you're not cheap to charter. ? But oil companies, budgets never |
|
| 61:13 | a problem for most oil companies. ? And so we would charter seaplanes |
|
| 61:20 | fly to andrews from Miami or have seaplanes pick us up in Nassau and |
|
| 61:26 | to Andras but we'd always circle first make sure there's no drug activity. |
|
| 61:33 | then they could lay the sea planes in the title channels and put the |
|
| 61:37 | of the seaplane up against the levy we get out and walk around |
|
| 61:42 | And we did that for years. then things got even more dangerous and |
|
| 61:47 | first got so dangerous that even the companies didn't feel comfortable being back |
|
| 61:53 | So, while we're walking around looking geology, the pilots will stand on |
|
| 61:57 | wings with semi automatic rifles just to sure there's no activity nearby. |
|
| 62:05 | everybody got to the point where enough this, right, It's just too |
|
| 62:11 | . And this is what got us Keiko's back in the 80s. |
|
| 62:16 | Alright, so let's sort of summarize Andrews model here and then we'll take |
|
| 62:23 | little break and we'll come back and about the Caicos tidal flats. |
|
| 62:29 | here's a cross section through Andrew's. , so the offshore restricted soft palate |
|
| 62:35 | environment is off to the right. is the channel belt. Alright, |
|
| 62:40 | the super title levies built up above level subtitle ponds in between title channel |
|
| 62:47 | down to bedrock potentially. And then Lana go marsh back here. All |
|
| 62:52 | . So, the classical sedimentary structures everybody wants to see in the rock |
|
| 62:58 | are associated with the super title Right? That was the crypto |
|
| 63:04 | The finesse troll fabric. The mud the rip up class. Okay, |
|
| 63:11 | they only make up a small part that title. Flat complex. |
|
| 63:15 | you'd have to hit the levee with four hole. Okay. And then |
|
| 63:20 | Illinois go marsh. Remember took hurricanes put sediment back here, winter storms |
|
| 63:26 | down one or two millimeters per event , as you're gonna see. Lay |
|
| 63:30 | centimeters a couple of centimeters every Okay, And so the stratification back |
|
| 63:37 | is thicker. All right, So is what people would call cryptic eliminations |
|
| 63:43 | you could use define strong catalytic Right? It is a form of |
|
| 63:48 | olympic fabric. Right, And then would be what the the thicker |
|
| 63:53 | strong catalytic fabric. Okay, alternating layers of, you know, |
|
| 63:59 | few centimeters of storm drive sediment interspersed the santa bacteria. Right, so |
|
| 64:07 | , you've got to be fortuitous to some of these areas of classical stratification |
|
| 64:12 | you hit the pond, you're never know you're on a tidal flat. |
|
| 64:15 | don't know how you could ever Okay. And that's where you probably |
|
| 64:19 | the term perry title. I'm not sure if I'm you know, |
|
| 64:24 | restricted marine or in the inner part a of a title flat. I'm |
|
| 64:29 | to use the term perry title to that uncertainty and call it a restricted |
|
| 64:35 | shallow subtitle environment. Okay. One last slide here, remember I |
|
| 64:45 | you the sea level curve yesterday? level shooting up like this and then |
|
| 64:51 | slow down is still a pretty good rate and then it slowed down even |
|
| 64:56 | for about 3000 years. And now popped back up to this. |
|
| 65:01 | so last 100 20 years, the of rise has increased dramatically. Look |
|
| 65:06 | the andrews tidal flats right now. they have done what they've moved from |
|
| 65:13 | high places in Ireland to the right . They pro graded. Okay. |
|
| 65:19 | people think they're still pro grading but only pro grading to the southwest. |
|
| 65:27 | . And you know This work the guy named Conrad deadline did back in |
|
| 65:34 | 70s. Some people have debated whether numbers are correct or not, but |
|
| 65:39 | argued a lateral pro predation rate of m per 1000 years or .8 m |
|
| 65:48 | like this, right? Every every . I mean you have to say |
|
| 65:54 | this whole system is pro graded To get this thing off shore to |
|
| 65:58 | it off of that hype licensing But look at the northwest side, |
|
| 66:02 | . This is what catches the brunt the strong winter storm effects. Those |
|
| 66:07 | winds are come out of the northwest and look what's happening right now. |
|
| 66:12 | stuff is actually eroding back. And the erosion is probably due in |
|
| 66:19 | also to this increase in sea level the last 120 years. Okay, |
|
| 66:26 | here's the lesson I want you to . We're going to get into this |
|
| 66:30 | this afternoon when we get into sequences cyclist city. Right? But the |
|
| 66:37 | photographers, they want to relate both and carbonates to being principally driven by |
|
| 66:43 | level change. Right? When, sea level falls, what do they |
|
| 66:48 | you systems pro grade. And when level rises, what do they tell |
|
| 66:55 | systems back step. Okay. And they turned that around in the rock |
|
| 67:02 | and when they see something pro they infer sea level did what |
|
| 67:08 | Right? If they see something the they say, oh sea level |
|
| 67:12 | Okay, They play that game. , well here What sea level been |
|
| 67:20 | for the last 120 years has been . So it's eroding here. |
|
| 67:27 | So you want to say that's due rising sea level, but why did |
|
| 67:31 | pro grade on the other side? what I'm saying? Makes no |
|
| 67:36 | Okay, you actually see this a in the rock record, both in |
|
| 67:40 | and plastics. They are classic examples you have a time where you have |
|
| 67:44 | delta, Right? And one side eroding and one side is pro grading |
|
| 67:50 | level. History is the same on side. Right? So you can't |
|
| 67:54 | it's due to to move move into level, there's some other environmental |
|
| 68:00 | Okay, so we'll get into this in much more detail later on. |
|
| 68:06 | , alright, well, let's let's our break here, 15 minute break |
|
| 68:10 | and we'll come back and talk about Caicos tidal flats. And then we'll |
|
| 68:16 | up by sort of summarizing the models steve margin platforms. Okay, |
|
| 68:26 | okay, we're going to start back and, And I'm gonna take you |
|
| 68:32 | to two keiko's platform. Again, show you an alternative way of making |
|
| 68:39 | carbonate tidal flat that has nothing to with with, with, with winter |
|
| 68:45 | and the occasional hurricane. And as appreciate now, by going to the |
|
| 68:52 | here, we're coming into the stronger trade winds system and into a drier |
|
| 69:00 | . So, you know, I took, took you through Andrew's |
|
| 69:03 | Novak writes to speak of associated with tidal flats. You don't get any |
|
| 69:09 | or in hydrate anything like that, , I mean, I guess you |
|
| 69:13 | say there are evaporate minerals from the that you precipitated proto dolomite and calcite |
|
| 69:21 | of seawater. But when we talk evaporate deposition, we're normally talking about |
|
| 69:27 | of gypsum or anhydride associated with some these environments. Alright, we're gonna |
|
| 69:33 | up there's gonna be some gypsum associated these tidal flats here because it's a |
|
| 69:38 | arid climate. I told you were to Hurricane Alley. So statistically, |
|
| 69:45 | sees a hurricane every 5.5 years and but being so far southeast, what |
|
| 69:53 | we get much of? We don't any winter storm effects. Right. |
|
| 69:58 | few winter storms ever make it this to the south. And even if |
|
| 70:01 | did the tidal flats occur on the side of these three islands here and |
|
| 70:06 | facing the wrong direction. Right, flat needs to face to the northwest |
|
| 70:11 | catch those stronger northwesterly winds related to cold front. Alright, so, |
|
| 70:18 | you look at the satellite photograph, are the three main Pleistocene islands on |
|
| 70:22 | north side of keiko's platform. This called north Caicos, Middle Caicos |
|
| 70:29 | Okay. And they're all high pleistocene again. And you can see on |
|
| 70:34 | south side uh plastered up against it these three islands are the tidal |
|
| 70:40 | Alright, so those are the oldest tidal flats. And they're shown here |
|
| 70:45 | green. Okay, and I told , excuse me, most of the |
|
| 70:53 | of the offshore sediments are grain stone , right, politic or skeletal, |
|
| 70:59 | there are some colloidal sands that occur here in the inner part of the |
|
| 71:05 | . Again, this is stand up three or four ft of water depth |
|
| 71:09 | here by two beta. It looks similar to the stuff I showed you |
|
| 71:14 | great bahama Bank. Alright. So is obviously the offshore source for the |
|
| 71:20 | that makes up these tidal flats. it's interesting that the scale of the |
|
| 71:26 | tidal flats is almost identical to what showed you for. Andrews. Uh |
|
| 71:32 | know, parts of andrews are a bit wider in places, but basically |
|
| 71:38 | scale, about 10 kilometers across. scale offshore subtitle channel belt in Leonardo |
|
| 71:46 | , everything plastered up against the high island of in this case north |
|
| 71:52 | And if you were to probe for at the edge of this title flat |
|
| 71:59 | , it's up to four m comparable thickness to what I showed you |
|
| 72:03 | an dress. Okay, so it's off flapping wedge up to four m |
|
| 72:09 | at the seaward edge here as it for for andrews. Alright, And |
|
| 72:16 | you fly over and look at these flats again at this scale, you |
|
| 72:21 | to see some differences compared to what showed you for Andrew's number. Andrews |
|
| 72:27 | well developed levies on the c the outer part of the channel belt |
|
| 72:33 | the ponds in between were mostly Well, look at look at this |
|
| 72:38 | here, we have some levy development the edge. But look at the |
|
| 72:43 | channels. The levee developments very poorly . You don't see good levy development |
|
| 72:49 | then look at the areas in between title channels, they're filled in because |
|
| 72:54 | colonized by scrub and grubs. So that's not a pond, that's |
|
| 72:59 | intertidal zone where the scrub mangroves We do have some ponds. You |
|
| 73:03 | see ponds back here in places, what's different here is that you filled |
|
| 73:08 | more of the inner channel area here what I showed you for. Andrews |
|
| 73:14 | you don't have good levy development here to andrews. Alright. In fact |
|
| 73:20 | is what it looks like on the , remember on Andrew's we had the |
|
| 73:25 | come up like this and slow back the Illinois. Go marsh, there's |
|
| 73:32 | even a levee here, right? flat, flat all the way out |
|
| 73:35 | the edge of the channel and it drops off and it's not white. |
|
| 73:40 | that darker color related to the tufted of Neema math. Okay, so |
|
| 73:46 | tells you there's no persistent overbanked deposition to winter storms like we had |
|
| 73:53 | Andrew's Okay, so we have to that. Alright, that's part of |
|
| 73:58 | story obviously. But it's a major between here and what I just showed |
|
| 74:03 | for Andrus island. Okay. And the other interesting feature is that there's |
|
| 74:14 | well let me back up. I to show you more of the inter |
|
| 74:20 | inner algal marsh. Uh, in of its composition and, and some |
|
| 74:26 | the attributes, I couldn't really do for the andrews because I didn't have |
|
| 74:32 | lot of photos to show. But can do that for keiko's. And |
|
| 74:37 | this is maybe a more typical expression the inner algal marsh that you would |
|
| 74:44 | both on Andros and keiko's right, continuous black algal mats and then the |
|
| 74:50 | development that we talked about before. if you, if you core |
|
| 74:56 | which we've done a lot on obviously keiko's, this is where you see |
|
| 75:00 | classical centimeter scale stratification. So you the storm layer. This is that |
|
| 75:06 | grain stone fabric laid down by a couple of centimeters of scale bars |
|
| 75:11 | centimeters you could see a couple of laid down by hurricane and then recolonized |
|
| 75:17 | the tufted matt and then it dies the next storm event. Another |
|
| 75:23 | Another storm event. Get the picture , how it works right? Hurricanes |
|
| 75:28 | bring in this kind of thickness, millimeter scale stratification is just limited to |
|
| 75:35 | winter storm effects. Okay, so want you to appreciate, you will |
|
| 75:39 | this fabric both on andrews and on said Neil and I'll go inland |
|
| 75:45 | Alright. And then we have one interesting fabric here on keiko's that you |
|
| 75:52 | see on Andros and that is offset the mouse of the title channels. |
|
| 75:58 | remember the photographs on Andros? The have the title channels come right out |
|
| 76:04 | the edge of the, of the . Right. And they just die |
|
| 76:09 | right there in the into the marine . But look at the offset and |
|
| 76:13 | photographs. All right. These are accretion features. Okay. Where everything's |
|
| 76:22 | displaced and you probably can guess the here. You're looking to the |
|
| 76:27 | Right? So which way do the winds blow? They blow east to |
|
| 76:31 | , Right? You're looking downwind with to the trade winds. So, |
|
| 76:35 | going on here? What's going on is when the trade winds blow the |
|
| 76:40 | , employable sediment in the shallow subtitle gets put in suspension. Okay. |
|
| 76:47 | then the waves that lap up against spitz will lay down sediment to build |
|
| 76:53 | low relief levy. That's the white you see right here. But then |
|
| 76:57 | happens to that suspended sediment? The title exchange will take that material and |
|
| 77:03 | it up the title channels and distribute into the ponds, but there'll be |
|
| 77:08 | overbanked deposition because you don't have a of water being pushed by a |
|
| 77:13 | Okay, everybody understand what I'm That's how you get the sediment into |
|
| 77:19 | inner part of this complex. the day to day. Trade winds |
|
| 77:25 | stuff up putting mud and pill Lloyd's suspension feeding it in persistently into that |
|
| 77:32 | pond. So, what have you ? Three times? You filled up |
|
| 77:35 | inner channel area. You shall load up into a intertidal zone. |
|
| 77:41 | so you don't get this on Andrew's . The trade winds are not strong |
|
| 77:45 | to first of all, you have wrong orientation. Right? The |
|
| 77:49 | tidal flats were protected with respect to trade winds anyway, but here this |
|
| 77:55 | more open exposure to the east and east. And this is what drives |
|
| 78:00 | deposition and then factor on factor in greater frequency of hurricanes. Okay, |
|
| 78:06 | it's a dual effect here of the trade wind effect and then the more |
|
| 78:12 | hurricane activity that has allowed this complex evolve to the state that it's |
|
| 78:18 | Okay, so on a windy day see the waves lapping up against the |
|
| 78:23 | edge of that conflict. That's where get the levee. Alright, this |
|
| 78:27 | will be laden with the mud and p lloyds. Okay, But basically |
|
| 78:33 | rest of that stuff then gets fed into the title five complex. |
|
| 78:37 | So if you compare the two, two systems, they both have similar |
|
| 78:43 | , they're both these off flapping wedges to four m thick at the seaward |
|
| 78:48 | , they're plastered up against a older the bedrock, Right? That's the |
|
| 78:55 | . You need a backstop for title deposition. You've got to have pre |
|
| 78:59 | topography or created during a sedimentary cycle deposition. But look at the difference |
|
| 79:08 | . Right. All the blue that see on Andros is the pond areas |
|
| 79:12 | are still unfilled. Okay. Most the deposition on Andros is focused in |
|
| 79:17 | yellow and green on the seaward edge the channel belt because of the winter |
|
| 79:22 | effects. All right. But look keiko's very poor levy development because we |
|
| 79:28 | have a mechanism to make good But we've added much more sediment to |
|
| 79:33 | system because we filled in the inner areas. And this is due to |
|
| 79:38 | persistent trade wind effect. Okay, kiko's has actually evolved to a greater |
|
| 79:43 | in terms of adding sediment compared to I showed you for Randers. |
|
| 79:50 | so two ways to make tidal One is to be exposed to the |
|
| 79:55 | storm effects. Okay, But you have to have that exposure. If |
|
| 80:01 | exposed to the trade winds, you an older backstop, you have a |
|
| 80:04 | to deliver sediment from the shallow subtitle onto the under the title flat. |
|
| 80:11 | , so, I want you to that. And then what do you |
|
| 80:14 | up here in some of these You pick up little very, very |
|
| 80:18 | discordant crystals of gypsum associated with some the Caicos title flat sediment. That |
|
| 80:25 | be mostly in the uh in the . Algo marsh it would be Neil |
|
| 80:30 | uncle marsh fabric. Okay. And it. Right. No, no |
|
| 80:37 | and no major evaporate deposition compared to I'm going to show you later |
|
| 80:43 | for abu Dhabi. Okay. And just to finish up here, I |
|
| 80:48 | you to appreciate what hurricanes do. told you, we've, we've monitored |
|
| 80:54 | on keiko's platform and I mentioned, hurricanes did some of the reef and |
|
| 81:00 | stuff yesterday. Uh, let me , show you. But Hurricane called |
|
| 81:16 | did back in 1985. So late hurricane came into November and here the |
|
| 81:23 | flats of interest that we just talked . Okay. And this is the |
|
| 81:29 | of hurricane Kate talked about hurricanes a bit right? The storm surge, |
|
| 81:33 | the circulation of hurricanes is counterclockwise. ? And they talk about where the |
|
| 81:40 | winds are, the strongest winds are out of the northern quadrant. |
|
| 81:44 | So people talk about the right hand . So where would the right hand |
|
| 81:48 | beyond this diagram and be up here the black arrow is. Okay, |
|
| 81:54 | where you get the strongest winds always a hurricane. And so let's just |
|
| 81:58 | the eye of the hurricane back to turk over here on the right. |
|
| 82:02 | the hurricane was coming east to the first wins with respect to the |
|
| 82:08 | flat, we're actually blowing north to , right. They were blowing water |
|
| 82:13 | of the tidal flat. So that nothing for tidal flat deposition. It |
|
| 82:17 | until the either hurricane got over here west Caicos that you got the return |
|
| 82:23 | from the south and southeast. That's you got deposition on the tidal |
|
| 82:29 | But those winds are not as strong the wind you would get from the |
|
| 82:35 | side. The right hand punch. . And this is a category one |
|
| 82:39 | that the top winds are about 90 . Okay, so let me show |
|
| 82:46 | what this hurricane did. We were keiko's two weeks after the hurricane passed |
|
| 82:54 | this is what it did. It the title flat complex. Okay. |
|
| 83:00 | you can see the white is the couple of centimeters of sediment laid down |
|
| 83:06 | hurricane kate. Alright. And this what it looked like on the |
|
| 83:12 | There's the poor side of the got buried, got killed. Hurricane |
|
| 83:18 | Lair 1-2 cm thick oxidized on the . This is a essentially a little |
|
| 83:25 | stone was laid down by the hurricane it took two years before this map |
|
| 83:32 | back and colonized that surface. so that's a what happens. |
|
| 83:41 | they die. They don't come back like this. Does the levies on |
|
| 83:46 | . Okay. Alright. Any questions the tidal flats story, Some of |
|
| 83:54 | things to look for in the rock . Alright, well let's summarize the |
|
| 84:01 | from the bahama platform complex and uh one that's ingrained in the literature is |
|
| 84:09 | one that you see here on the left. This is the cartoon, |
|
| 84:13 | started with yesterday And it says you a shallow water carbonate platform by definition |
|
| 84:21 | m of water depth or less dropping into a really deep water basin. |
|
| 84:25 | in this model, where is the of high energy? It's along the |
|
| 84:29 | where oceanic currents or swells provide that . So you get reefs or you |
|
| 84:36 | fluids, but you don't get the together and then that energy dissipates and |
|
| 84:41 | get a broad area of more subtitled colloidal sand and mud that may |
|
| 84:47 | may not feed a tidal flat on back side. Okay, of |
|
| 84:51 | deeper pelagic carbonate deposition out to the , if you're a Mesozoic and younger |
|
| 84:58 | . Okay, so remember the setting , Northern Bahamas refer to Great bahama |
|
| 85:04 | . Grand bahama Bank. I'm little bahama Bank and oceanic setting General |
|
| 85:13 | trade winds, common winter storms, frequent hurricanes compared to the Caicos. |
|
| 85:19 | , so here's the map I showed before, and I'm gonna show you |
|
| 85:27 | cheat ahead here. I'm gonna show The basis for this model came from |
|
| 85:35 | that the carbon, a geologist named Purdy did back in the 60s up |
|
| 85:41 | on the northwest side of Great Bahama . Okay, so I'm gonna show |
|
| 85:45 | his data and the variation on the . And then I'm going to show |
|
| 85:50 | a few other aspects associated with the Bahamas, that people have drawn on |
|
| 85:55 | explain some of the things we see the rock record And then I'll contrast |
|
| 86:00 | with keiko's. All right. I told you most of the sedimentation |
|
| 86:05 | is non skeletal grain dominated. I there are a couple of reefs that |
|
| 86:11 | in the northern Bahamas, but they're to the east facing and open ocean |
|
| 86:16 | sides of these platforms. So off Andrews off of Eleuthera, off of |
|
| 86:21 | up here and Andrew has a good right here. It's it's the second |
|
| 86:27 | barrier reef in the caribbean after Okay. And it catches oceanic swells |
|
| 86:33 | come out of the atlantic and they in here through Northeast Province Channel and |
|
| 86:38 | drive reef deposition in that position Okay. And this is this is |
|
| 86:43 | the reef looks like from the So this is the east side of |
|
| 86:48 | . The other side of Andrews was tidal flat that we just talked |
|
| 86:51 | This is the barrier reef that occurs the edge here, you can see |
|
| 86:55 | cuts, you can see the like we talked about yesterday, the |
|
| 86:59 | reef, lagoon and then the Right? This is the deep water |
|
| 87:04 | of the ocean. Okay, so a little bit of reef here, |
|
| 87:09 | it's limited because of the exposure. need that exposure to the open |
|
| 87:13 | And remember their barrier reef here means no electric sand behind it. |
|
| 87:20 | that's the default principle that we talked yesterday. Okay, so most of |
|
| 87:26 | bahama bank shows a sedimentary environment Pattern by this cartoon. This is the |
|
| 87:33 | of purty back in the 60s. basically what he says is the marginal |
|
| 87:41 | platform margin is dominated by strong tidal , tidal currents don't make reefs. |
|
| 87:48 | you get horrible sand environment first politic it. And he mapped in |
|
| 87:55 | The what what what he map in is what I call the active analytics |
|
| 88:00 | yesterday and then the grape stone in is what I call the stabilized holistic |
|
| 88:07 | yesterday. Okay. And then he the more inboard, more restricted lower |
|
| 88:14 | part of the profile, mud And he broke it out into more |
|
| 88:19 | hard pellet sand and more restricted soft line. But okay. And so |
|
| 88:25 | is the model that got ingrained in literature back in the 60s and this |
|
| 88:28 | what influenced industry for for decades. . And what are the implications if |
|
| 88:35 | gonna explore for high energy faces? just explore the margin, right? |
|
| 88:40 | look for reefs, You look for . It's okay, ignore the platform |
|
| 88:47 | . Okay, you're not gonna go muddy sediment unless you have some idea |
|
| 88:51 | it was favorably altered I genetically to you reservoir quality. Okay, so |
|
| 88:58 | the model. All right. And know, there's nothing wrong with this |
|
| 89:02 | . It's just it's one model. ? And but but there are a |
|
| 89:06 | of problems with the model. The he presented it here. And the |
|
| 89:08 | is there's no scale. Okay, this is a valid model if your |
|
| 89:15 | is 100 km across for scale like is today. Alright, But what |
|
| 89:20 | your platform is only, say 10 20 km across it may not, |
|
| 89:26 | may not be able to create a water inner part to that platform, |
|
| 89:31 | what I'm saying. So you always to think about the scale when you're |
|
| 89:35 | these bottles. And then basically he's off with a flat tabletop and building |
|
| 89:41 | deposits off of that. You think gonna be the common theme in the |
|
| 89:46 | record. Now, you're gonna have earlier cycle of sedimentation. Whether it's |
|
| 89:51 | are classics that built a topography, ? Carbonate reef, classic barrier |
|
| 89:59 | something like that. Right. And that pre existing topography always carries through |
|
| 90:04 | the next cycle of sedimentation. So have to factor that in when you |
|
| 90:09 | these bottles. Okay, But this basically the map that he published on |
|
| 90:16 | is the basis for that diagram. can see the coral sand along the |
|
| 90:21 | politic behind it and then a broad of lime mud deposition soft, I'm |
|
| 90:27 | , hard fecal pellets would be the pink would be the soft, what |
|
| 90:32 | called paella tidal mud. We now the term P Lloyd for that, |
|
| 90:38 | would be the soft pillow Lloyd Okay. And notice again where the |
|
| 90:43 | mud, where the soft palate lime is It's behind andros because of the |
|
| 90:49 | shadow. There's no pink to the or south. The sediments forming |
|
| 90:54 | But what happens to it? It stripped off to the west by the |
|
| 90:58 | easterly trade winds setting up this Cross bank currents. And I'll show |
|
| 91:02 | the byproduct of that. Okay, this is what the core angle environment |
|
| 91:09 | like underwater. It's not a reef a classical sense, it's not a |
|
| 91:13 | up, it's a rocky bottom. of that rock is actually just pleistocene |
|
| 91:19 | and it's covered with scattered coral and growth. It's producing a veneer of |
|
| 91:25 | sand. So most of these are of coral and mollusks and red |
|
| 91:29 | green algae. This is the spine an encounter. Okay, these are |
|
| 91:34 | soft coral. Okay, but you that. They're right. You need |
|
| 91:41 | veneer sentiment to feed us sand environment it because it needs nuclei. |
|
| 91:48 | In order to make nuclei. so the two go together. But |
|
| 91:53 | doesn't go together as a barrier reef sand behind it. Okay. And |
|
| 92:00 | a variation on the theme was when got to the southern end of tongue |
|
| 92:04 | the ocean or the northern end of . Sound where I worked, we |
|
| 92:09 | the same basic pattern. Right? what's different? What's different is the |
|
| 92:15 | ? Sand is greatly expanded. Remember on the western side over here |
|
| 92:21 | the currents were the weakest, Right , not tidal current, your sand |
|
| 92:25 | is only one or two kilometers across that's that's that's just much energy as |
|
| 92:32 | could generate two. You can only that kind of scale of sand |
|
| 92:36 | But when you come to the ends these deep water environments where the currents |
|
| 92:39 | two or three times stronger, look you have, you have horrible |
|
| 92:44 | hard palate, soft belt, you the same pattern, but what changes |
|
| 92:49 | thick the width of that c high energy sand? Right, because |
|
| 92:53 | a reflection of the stronger tidal current . Those are the title bars that |
|
| 92:59 | talked about yesterday. Okay. And to to sort of finish this |
|
| 93:05 | there are three other things that have out of studies done in the so |
|
| 93:09 | northern Bahamas over the last 50 years so and I've highlighted three areas that |
|
| 93:18 | going to talk about here very briefly the first has to do with the |
|
| 93:23 | cores that were collected back in the in southern tongue of the ocean. |
|
| 93:29 | the tongue of the ocean is 2700 deep right here. Alright, and |
|
| 93:35 | study by Draxler and Schlager Schlager documented first example of Hiestand shedding. |
|
| 93:42 | so we had this discussion yesterday, had it last weekend about why carbonates |
|
| 93:48 | shed a lot of material during low , right? They sit high and |
|
| 93:52 | , they get cemented, they'd shed flooding after they get flooded. So |
|
| 93:57 | gonna show you that data to prove . Okay. And then I'm gonna |
|
| 94:01 | you over here and show you data a seismic based, uh, from |
|
| 94:06 | western margin of great drama back. is by definition the leeward margin and |
|
| 94:12 | going to show you what the general trade winds do in terms of of |
|
| 94:17 | they shut off of that leeward margin how much they shut off for a |
|
| 94:22 | period of time. Okay. And see the implications for things like sequence |
|
| 94:28 | . And then the last example up , the work that hein and newman |
|
| 94:30 | back in the 70s, they documented trying to develop on the leeward |
|
| 94:37 | but they could only follow or track level to a point and the point |
|
| 94:42 | , once you flooded the rest of platform. What happened to those |
|
| 94:46 | They got smothered by off bank transportation they never develop their full potential. |
|
| 94:53 | , so let me show you the for these. All right, These |
|
| 94:57 | going to bear directly on our plate discussion next week. Okay. Where |
|
| 95:04 | get these reservoirs and what controls their and distribution. Okay, so this |
|
| 95:10 | is based on piston cores that the , It's part of his PhD dropped |
|
| 95:18 | the tongue of the ocean, right cores are free falling cores that they |
|
| 95:24 | let settle down into 2000 m of and with the force of gravity they |
|
| 95:34 | through the whole scene and into the because none of that stuff is consolidated |
|
| 95:40 | hasn't been buried. Right. And that's how they capture this material. |
|
| 95:45 | . So these are this is data three piston cores and they collected |
|
| 95:51 | many more cores than this. All . And so let me explain what |
|
| 95:55 | seeing here. Alright, so you a red curve for each of these |
|
| 96:01 | . That's the Reaganite abundance curve greater the right, less to the |
|
| 96:07 | but never dropping to zero because what out in the tongue of the ocean |
|
| 96:13 | and back in the Pleistocene. A gaster pod that I called the terror |
|
| 96:20 | last weekend. I'm sure you don't this but I briefly mentioned it, |
|
| 96:24 | it's a floating gastro pod. That's rag genetic. Okay. And it |
|
| 96:29 | in the upper part of the water and then it dies and settles down |
|
| 96:33 | deeper water. Okay, so there's the supply of this magnetic material and |
|
| 96:39 | why arrogant. I'd never drops to . Okay. And then what are |
|
| 96:45 | orange and blue bars represent? Those the different stages we use in the |
|
| 96:51 | . Alright. And they're tied back sea level history. So stage one |
|
| 96:57 | our present day Hiestand condition right where see level, came up 18,000 years |
|
| 97:04 | , started coming up and flooded the 5-7,000 years ago. Okay. And |
|
| 97:10 | stage 2-4 is our last pricing low when sea level dropped the platforms are |
|
| 97:18 | and dry. They're undergoing Kearse The glaciers were expanding on the |
|
| 97:23 | Okay. And then five would be Pleistocene Hiestand. That equates to about |
|
| 97:31 | and 2,240,000 years ago. And then would be another low stand and seven |
|
| 97:38 | be another high stand. Okay, are these dated? They're dated by |
|
| 97:44 | at the isotopic signatures of the plastic in the sediment. Remember the You |
|
| 97:52 | don't remember this but I mentioned the oxygen isotopes, Right? The 18016 |
|
| 97:58 | is controlled by temperature. Okay, you can tell from that data whether |
|
| 98:04 | forearms lived in cooler water or warmer and you can relate that to high |
|
| 98:10 | or low stains. Okay, so how they figure that out. |
|
| 98:15 | And then the black bars, you here are the turbine sites of shallow |
|
| 98:19 | carbonate material shed into deeper water. , so let's just go through |
|
| 98:24 | It's pretty obvious right? That look the low stands and blue. There's |
|
| 98:31 | any turbo tight material being shed into basin, greater frequency, greater thickness |
|
| 98:36 | shedding always occurs during the orange intervals are the high stands. Okay. |
|
| 98:44 | this data was already public. These had already talked about this before they |
|
| 98:49 | this paper before Exxon started into their strata. Graphic stuff. Alright, |
|
| 98:55 | shame on them for ignoring this stuff ? To treat carbonates and classics as |
|
| 99:01 | the same. But but that's what did. There's a reason for |
|
| 99:06 | We can talk about later. But , everybody appreciate what I'm showing |
|
| 99:10 | Right? Hiestand shedding. As I yesterday is the norm for carbonates. |
|
| 99:14 | is the first database that proved Now, this has been done now |
|
| 99:19 | the off of the Maldives, in indian ocean. Been done off the |
|
| 99:24 | rise in the western caribbean. It's done off the great barrier reef in |
|
| 99:29 | . Every one of those studies shows . Okay. All right. Just |
|
| 99:37 | opposite of what you'd expect for a setting. Okay. And then the |
|
| 99:43 | study by uh by Wilbur and others to document just how much stuff gets |
|
| 99:51 | off during high stance. Okay. how does it get re deposited around |
|
| 99:55 | edge of the platform. So what looking at here are three cross sectional |
|
| 100:01 | taken on the western margin of great Bank. So this one is south |
|
| 100:08 | Andros. Right? So andrews will here. Here's the edge of the |
|
| 100:12 | here. Okay, So one line down here south of Andrews. The |
|
| 100:18 | line in the middle here is directly of Andrews and the third line is |
|
| 100:23 | of Andrew's. Okay. Everybody appreciate we're situated. All right, The |
|
| 100:30 | here represents the older pleistocene platform Okay. And each red bar that |
|
| 100:38 | see here shows you where sea level 18,000 years ago, 100 20 m |
|
| 100:44 | than it is today. Okay, that means all of this platform was |
|
| 100:49 | and try during the last low right, undergoing car certification? No |
|
| 100:55 | carbonate sedimentation. Okay. And then happened? Sea level started coming up |
|
| 101:01 | it started to flood over the edge the platform about five or 6000 years |
|
| 101:07 | , but it really didn't flood the carbonate platform until about 3500 years |
|
| 101:14 | Okay, And so In 3500 years have done. We put this along |
|
| 101:23 | edge here because this yellow sediment dates his holy scene age. Okay, |
|
| 101:29 | it has to have come over after flooded the platform. Okay, this |
|
| 101:33 | the stuff. This is the lime and silt sized material that is picked |
|
| 101:38 | a suspension by cross bank currents related the general easterly trade winds and pushed |
|
| 101:46 | the edge. Okay, Now look the scale here, that's 100 |
|
| 101:52 | See, this lower wedge here is m thick. That's 90 m of |
|
| 101:59 | lime mud and silt sized carbonate material over at 3000 3500 years. |
|
| 102:06 | that's incredible. All right. very rapid rate of deposition. |
|
| 102:14 | You see the same thing north of . And then look at here, |
|
| 102:18 | hardly anything here. So either nothing shut off of Andrews due west of |
|
| 102:26 | right because of the blocking effect of Vandross on the trade winds or maybe |
|
| 102:32 | stuff just bypassed and went into deeper . You we can't know for |
|
| 102:37 | but it's probably due to the blocking of the Van Drew's. Okay. |
|
| 102:43 | I don't know how familiar you guys with seismic street graffiti. Right? |
|
| 102:49 | different ways to do seismic photography and approach this issue differently, but the |
|
| 102:55 | that's published the most on this is . Right? The Exxon way of |
|
| 103:01 | seismic strategic graffiti is to look for so called basically restricted wedges which are |
|
| 103:05 | yellow feature to see there and wherever see them lap up against the |
|
| 103:11 | whether it's carbonate platform or continental How do they interpret this? The |
|
| 103:17 | of this wedge they always interpreted as low stand. Okay, this is |
|
| 103:23 | Pete vale put together the this sea curve for the fan of Rizzo, |
|
| 103:31 | ? Mostly from seismic data. So will get a database in from |
|
| 103:36 | They look for the straddle patterns. look for the on lap termination of |
|
| 103:41 | up against the platform. They see on lapping wedge that would be for |
|
| 103:47 | , that would be the evidence for drop in sea level and that's how |
|
| 103:50 | put their sea level curve together. , But you see the folly of |
|
| 103:55 | approach, right? This is not to drop at sea level. This |
|
| 103:58 | a high stand, which you have be very careful about how you use |
|
| 104:05 | . The geometry on seismic lines to sea level history. Right? That's |
|
| 104:11 | good enough. All right. And the problem. All right. And |
|
| 104:18 | mean, I told you I worked Exxon when I, when I came |
|
| 104:21 | of school, I worked for Exxon eight years. I worked at the |
|
| 104:24 | lab where people worked his office is a few doors down from my office |
|
| 104:29 | he could walk into his office and the on the wall he had a |
|
| 104:33 | level cycle chart. Okay. We this huge diagram plotting sea level through |
|
| 104:40 | time. It was all in It's in pencil because every time you |
|
| 104:44 | a new seismic line, if you something different, change it. |
|
| 104:49 | Based on the style of geometries. could never ever accept the carbonates in |
|
| 104:55 | that responded differently to sea level. ? He treated both the same. |
|
| 105:01 | wanted this grand unified model where all needed was seismic and and bio strategic |
|
| 105:09 | . And you could predict what sea was doing or tell people what sea |
|
| 105:13 | was doing. And that's not good . Okay, so appreciate Hiestand shedding |
|
| 105:21 | the norm. We have Hiestand wedges commonly and lots of carbonate successions has |
|
| 105:28 | to do with the drop in sea . Okay, everybody appreciate what I'm |
|
| 105:33 | . All right. And then the example was up to the north of |
|
| 105:37 | bahama Bank. The work that hein Newman did was they showed that, |
|
| 105:43 | know, after you drop sea level terminate carbonate deposition up here, back |
|
| 105:48 | the pleistocene and you started to raise level again. They noticed during the |
|
| 105:54 | that reefs actually started to develop on leeward margin. And they tracked the |
|
| 105:59 | sea level. But they only tracked to a point. And the point |
|
| 106:04 | when you flooded the rest of the interior. And then what happened? |
|
| 106:08 | started your carbon a machine back here being on the leeward margin, what |
|
| 106:13 | off leeward margins? You preferentially shed east to west. Right, So |
|
| 106:20 | do you do? First thing you is you start stressing the reefs. |
|
| 106:25 | can kill the reefs without actually physically it with sediment. You can start |
|
| 106:30 | little thin layers of sediment, very little layers of sediment on top of |
|
| 106:34 | corals. That's going to start to and stress the reef and then when |
|
| 106:38 | bury it, obviously that kills Right? So the takeaway from their |
|
| 106:44 | was, yeah, you might develop only word margins, but they're never |
|
| 106:48 | keep pace with sea level. They're going to reach full maturity where they |
|
| 106:52 | up into a reef flat. In words, they're never going to get |
|
| 106:57 | their optimum thickness and for that maybe we shouldn't be chasing these reach |
|
| 107:02 | . Maybe the reservoirs are not going be fully developed, not have good |
|
| 107:06 | , not be economically viable. Conrad Newman, it was an interesting |
|
| 107:13 | and he always, when he lectured lectured and showed this slide, he |
|
| 107:18 | always say those poor reefs, they shot in the back by their lagunas |
|
| 107:24 | and they did right by off bank , dress right. They killed the |
|
| 107:29 | . Alright, So you can see this affected industry actually affected industry for |
|
| 107:35 | couple of decades, right before people , wait a minute. Maybe their |
|
| 107:39 | to overcome the softbank transportation. Sometimes storm could build an island right in |
|
| 107:46 | and block off bank transportation. That will allow the reef to thrive |
|
| 107:50 | the other side. What if your interior deepens as you come up onto |
|
| 107:55 | platform, it's more like this. ? More of an atoll kind of |
|
| 108:00 | where it deepens a little bit the deepening effect would also inhibit off |
|
| 108:05 | transportation. Okay, so I don't you to get the impression that leeward |
|
| 108:10 | are not places for good reefs. actually can be. And you'll see |
|
| 108:14 | type examples of that next week. , but you still have to overcome |
|
| 108:20 | effect of inhibiting off bank transportation. that's part of the thinking that has |
|
| 108:25 | go into that evaluation. Okay, , so this is gonna these diagrams |
|
| 108:35 | us into our discussion next weekend. , I'll build on all of this |
|
| 108:40 | weekend. We can we talk about carbonate plays? But this is a |
|
| 108:44 | of what I've just said for the Bahamas. Right. And you can |
|
| 108:48 | , you know, high energy faces to the platform margin. Everything is |
|
| 108:53 | by oceanic processes, either oceanic swells tidal currents. So good reef |
|
| 109:01 | Platform margin barrier reefs only occur on open ocean side of these platforms. |
|
| 109:06 | reefs are isolated, poorly developed, dominate where the currents are operative, |
|
| 109:15 | ? But you don't get briefs and together. Right. At the default |
|
| 109:20 | , we saw platform materials are mud and we saw that the trade winds |
|
| 109:25 | only capable of sloughing off for shedding grain lime mud or silt sized |
|
| 109:32 | And the result were the on lapping like you saw in the previous couple |
|
| 109:37 | diagrams. Okay. And no vaporize it's too rainy. Okay, so |
|
| 109:43 | the northern Bahamas. Alright. And what are the expiration connotations? As |
|
| 109:49 | said, you would play the margins reefs or depending on orientation and you |
|
| 109:56 | the platform interior. Okay. And wouldn't play for a good reef development |
|
| 110:01 | the leeward margins because of the off sediment stress. Okay. And that's |
|
| 110:08 | been ingrained in the literature for literally . Okay. Right. And keiko's |
|
| 110:16 | little bit different story. Right. trade winds changed the story a |
|
| 110:21 | We, I showed you that there platform margin barrier reefs that face the |
|
| 110:25 | atlantic. But the trade winds actually the reef development. They make them |
|
| 110:31 | more mature because they provide, they the circulation on the reef. I |
|
| 110:37 | you you could get isolated patrick's that well up onto the carbonate platform because |
|
| 110:42 | the trade winds. You don't see in the northern Bahamas, leeward margin |
|
| 110:47 | , you can develop if you could off transportation or you can change the |
|
| 110:52 | . Like I showed you yesterday to exposure to some of the trade |
|
| 110:56 | But those reefs are not going to long, linear barrier reefs are still |
|
| 111:00 | to be isolated reefs, but they be fully mature. And then what |
|
| 111:05 | happen is some of the sand behind can be converted to analytic material. |
|
| 111:10 | , so we can have reefs and together and we can have more widespread |
|
| 111:16 | material sands developed like I showed you keiko's linear sand bodies parallel to the |
|
| 111:22 | winds, widespread sand body sheets, sand bodies line up parallel to the |
|
| 111:29 | where they face into the prevailing with , and then yesterday we talked about |
|
| 111:36 | . Not only did the trade winds strong, trade winds shed mud and |
|
| 111:40 | sized material, but they carbonate sand the edge. So the on lapping |
|
| 111:44 | are going to be grain stone prone other words have good reservoir quality. |
|
| 111:50 | I said we do have some evaporates this platform. I mentioned the tidal |
|
| 111:55 | . And then last week I showed the the coastal Selena's that had the |
|
| 112:01 | associated with them. Okay, so little bit different setting here. |
|
| 112:07 | So Caicos is a hybrid model. it's obviously influenced by oceanic conditions on |
|
| 112:14 | of the open ocean side of the where you get the barrier reef, |
|
| 112:18 | really it's the easterly strong easterly trade that really drive deposition on that |
|
| 112:23 | Okay, this changes the whole Okay. Not only now can you |
|
| 112:30 | for the margin? Looking for reefs high energy sands along the margin? |
|
| 112:37 | now you can explore the inner part the platform. Right? Looking for |
|
| 112:42 | sands. Looking for linear sand bodies line up parallel to the trade winds |
|
| 112:47 | perpendicular if they're plastered up against the mass. Okay. And you can |
|
| 112:54 | on lapping wedges off the leeward margin for grain stones. Okay, so |
|
| 113:01 | the whole story. And actually I it better explains a lot of the |
|
| 113:06 | types in the rock record that were by serendipity by accident. Right? |
|
| 113:13 | just drilled off the side being not exactly what they're drilling and they found |
|
| 113:18 | stuff by accident, but it never any sense based on what I just |
|
| 113:22 | you for the northern Bahamas. so I think this this helps us |
|
| 113:28 | some of the play type distribution in in the subsurface. Okay, so |
|
| 113:35 | any questions about that? We're going build on this obviously a lot next |
|
| 113:39 | . All right. You'll see the . All this modern stuff. Uh |
|
| 113:43 | , you see some of that this , but you see it to the |
|
| 113:46 | type discussion next next week. I thought I would just finish up |
|
| 113:51 | show you what hurricanes due to some these environments. So you appreciate I've |
|
| 113:56 | showed you what it did to the flats. Alright, remember hurricanes are |
|
| 114:05 | and try to tropical subtropical belts. where they form. Okay, They |
|
| 114:10 | form in colder water climates. They move into colder water climates and eventually |
|
| 114:15 | , but they get pushed east to by the trade winds. They don't |
|
| 114:20 | into the doldrums. Remember that 5° either side of the equator is the |
|
| 114:26 | where the trade winds don't blow. don't get hurricanes, they don't cross |
|
| 114:30 | that. They don't cross the Okay. And appreciate the frequency |
|
| 114:38 | And this is, I've not seen update this since the 19, since |
|
| 114:42 | but I think this is good enough make the point here, right? |
|
| 114:46 | keiko's platform, the red dot There's andros that we talked about up |
|
| 114:51 | . I mean, look at the of hurricanes. I mean, it's |
|
| 114:56 | . Right. And I mean, is something you need to think about |
|
| 115:01 | you're evaluating evaluating any shallow marine carbonate . Right. There's day to |
|
| 115:09 | Excuse me, day to day Right. That are operative like the |
|
| 115:15 | winds or tidal currents and swells and like that, but every 5.5 |
|
| 115:22 | seven a half years, 20 whatever it is, still pretty quick |
|
| 115:27 | , there's a hurricane, right? it's the little one and sometimes it's |
|
| 115:31 | big one. All right. And that has an effect on not only |
|
| 115:36 | occurs in shallow water, but has effect on how stuff is moved from |
|
| 115:40 | to deeper environments. Okay, so is andrews. I'm sorry, this |
|
| 115:49 | Hurricane Andrew that hit Miami in August 1992. Andrew was a category five |
|
| 115:57 | winds were over 100 and 50 miles hour when they came through Miami. |
|
| 116:03 | this is a different kind of hurricane it was fast moving. It was |
|
| 116:08 | like 20 miles an hour, which more like a tornado and not a |
|
| 116:12 | hurricane. But let me just share you some of the stuff that it |
|
| 116:17 | here. Alright. It came through decimated uh, the city of Miami |
|
| 116:24 | of downtown downtown is right there and major destruction obviously. But but it |
|
| 116:31 | did some interesting, it didn't do lot of marine damage, but it |
|
| 116:33 | a lot of damage on land. first thing it did was south of |
|
| 116:38 | is a major agricultural district district where grow lots of tomatoes and cucumbers and |
|
| 116:45 | . I mean, it's a breadbasket southeast part of the U. |
|
| 116:49 | Okay. And what that what that did was, you know the farming |
|
| 116:57 | has a nice soil that sits on bedrock, right, limestone. So |
|
| 117:03 | the bedrock and then between the soil the bedrock you actually get all these |
|
| 117:08 | , right? This is the soil up of the underlying bedrock. It |
|
| 117:13 | these pebbles and stuff like that. then so what this hurricane did was |
|
| 117:18 | stripped off all the soil and then took the pebbles and put in suspension |
|
| 117:25 | there were mailboxes six ft above the level, filled with pebbles. |
|
| 117:32 | On these farms there were steel. you know the steel sheds of the |
|
| 117:39 | the farm buildings and 20 ft up this corrugated steel. There were all |
|
| 117:44 | holes in the steel. Those are pebbles that went through the steel were |
|
| 117:48 | in suspension by the hurricane. so that's what it did on |
|
| 117:53 | And then this is the Everglades, ? The famous Everglades National Park and |
|
| 118:00 | here in the southern part of the , there were mangrove trees, I |
|
| 118:04 | you the scrub ones right, there mangrove trees 60 to 80 ft high |
|
| 118:09 | they all got knocked over like this the winds. Remember you ever see |
|
| 118:15 | of Mount ST helens after the volcano in Washington. You know what I'm |
|
| 118:22 | about? This is back in my early eighties, I guess half of |
|
| 118:28 | ST helens blew out right and it's up this this shock wave that just |
|
| 118:36 | down the mountain and all the trees knocked over like this just like |
|
| 118:41 | But due to the hurricane. So, we've we know three heard |
|
| 118:51 | major hurricanes have hit keiko's platform. what's really eerie is they've all hit |
|
| 118:58 | the same day And Month, September . So, people on Keiko's get |
|
| 119:05 | nervous when September seven comes around for good reason. All right, Donna |
|
| 119:10 | a category four hurricane. And then been working. We weren't working there |
|
| 119:16 | that long ago. But but we air photo data that shows what Donna |
|
| 119:22 | . Alright. It cut through islands created the cuts that filled other |
|
| 119:27 | Right? But we've we've monitored what can Irma have done right. I |
|
| 119:32 | through and took 2008 and Irma came back in 2017. Alright, So |
|
| 119:38 | is hurricane ike coming from the atlantic over Keiko's and I remember I still |
|
| 119:46 | that had a bad feeling that it headed toward my house, which |
|
| 119:52 | it did hit Houston. Right. did a lot of damage and we |
|
| 119:58 | have a lot of damage in my . We had no power for two |
|
| 120:01 | , which is a big pain Right? So, so, I'll |
|
| 120:06 | forget that. And then Irma Hit Rico 1st, right? The damage |
|
| 120:14 | Puerto Rico and then it came up and went right across Keiko's. And |
|
| 120:19 | this category five, both were category . Well, uh, Ike was |
|
| 120:25 | category four hurricane up to about 100 45 mile an hour winds and Irma's |
|
| 120:30 | . Okay, A major hurricane. . And what's really unusual is Irma |
|
| 120:35 | right across the platform and usually when get into shallow water on a |
|
| 120:40 | they lose energy. It never lost . It kept that strong wind all |
|
| 120:45 | way across. Right, Alright. there's the wind field of Irma. |
|
| 120:50 | , so let me just show you , what these hurricanes do and what |
|
| 120:54 | geological implications are. Okay, so is a satellite photograph the day before |
|
| 121:01 | hit. This is after the day you can see what the hurricane |
|
| 121:06 | It stirred up mud put in suspension only on the platform. That's where |
|
| 121:13 | put it in suspension on the And then what happens the currents right |
|
| 121:17 | them offshore into deeper water and then settle out, right. That's how |
|
| 121:23 | deliver fine grain sediment from shallow to . Remember talking about yesterday, the |
|
| 121:29 | eliminations and the deep water basins, . Okay, That's that's how you |
|
| 121:33 | deliver that sediment to get the settle effect. All right. What you |
|
| 121:39 | appreciate is that, you know, were on, we were on keiko's |
|
| 121:44 | a month after the hurricane hit. when we flew into the island |
|
| 121:50 | we could still see these plumes of laden water offshore. Okay. And |
|
| 121:55 | fact, stuff was still in suspension the platform almost a month after the |
|
| 122:02 | . That's how long this blood stays suspension. Okay, So, and |
|
| 122:08 | we have the civil reef called ike that sits here uh, in this |
|
| 122:14 | part of the platform where there's no reef. And we've been, we |
|
| 122:19 | this reef back in uh 2005, guess. And we monitored it. |
|
| 122:26 | ? It's a, it's driven by swells to just roll right in here |
|
| 122:30 | part of that reef trend that runs through here. And we watched this |
|
| 122:35 | . Well, when we found it already built up the sea |
|
| 122:38 | Okay, that's how we found It was sticking out of water during |
|
| 122:42 | spring low tide sticking this far out water. The corals are out of |
|
| 122:47 | and we were just, we were voting by here. We visited the |
|
| 122:50 | would show. And we're coming up to the north and we saw this |
|
| 122:54 | and we had to stop and look it. Right. And so this |
|
| 122:57 | like reef and it's part of a of reefs that occurred back in this |
|
| 123:02 | , right here. Okay, so what I did to the reef. |
|
| 123:08 | , so here's a photograph from one our seminars in May of 2008 before |
|
| 123:13 | hurricane where essentially this big, massive , Acapulco Palme had built right up |
|
| 123:19 | sea level. And then I came and you can see what it did |
|
| 123:25 | cut it back about basically about 10 down, right? Remember this reef |
|
| 123:32 | in about 25 or 30 ft of . Alright. So it's built up |
|
| 123:36 | substantially and it cuts it back. . But it doesn't kill everything, |
|
| 123:42 | know? So this is a year and you can see there's already corals |
|
| 123:47 | to come back because these corals recovered quickly and grow pretty quickly. And |
|
| 123:52 | look at eight or nine years of where it started to build back the |
|
| 123:56 | level. But still this is still maybe four ft of water, five |
|
| 124:01 | of water. Okay. So it gotten up to what it was before |
|
| 124:05 | hurricane. Alright. And then so just watched this again until 2017. |
|
| 124:12 | then what happened on September 7th 2017 came through like a bulldozer and just |
|
| 124:21 | The Reef. Alright. It's like really looks like somebody took a bulldozer |
|
| 124:27 | and just scraped all the living coral of it. Alright. Not all |
|
| 124:31 | coral died again. Some of it the backside survived, but I |
|
| 124:35 | this is almost 20 ft of Okay. And it's going to take |
|
| 124:41 | long time before this reef comes All right. So we were on |
|
| 124:45 | streets in 2019. Um So a bit more recovery. Haven't been back |
|
| 124:52 | 2019 because of Covid. You we're hoping to run a trip here |
|
| 124:57 | May and uh we'll see what it like. But I expect it to |
|
| 125:02 | pretty much like this with a little more coverage of coral, but still |
|
| 125:07 | long way to go before it gets recovery. Okay. And then we |
|
| 125:14 | about Amber Scholl yesterday. Right? showed you the video Amber Scholl and |
|
| 125:20 | Amber's key is were built up above level to make an island and here's |
|
| 125:26 | western tip of Ambergris show before Okay. Where you had the well |
|
| 125:33 | shoulder with the boiling water During the trade winds? Okay. And then |
|
| 125:39 | the same tip, but a different . Look at the sand body that's |
|
| 125:43 | obvious in this photograph is you don't the sand. Okay. We couldn't |
|
| 125:48 | essential when we voted here in Alright, let's see what the hurricane |
|
| 125:54 | was it took that sand body and basically just splayed it out like a |
|
| 125:58 | knife, right, spread it out that's how you expand the limits of |
|
| 126:04 | sand body. Alright. And But was like four ft of water right |
|
| 126:11 | and it used to be, you , a foot of water and we |
|
| 126:16 | see any boiling water because it was deep to be actively agitated. I |
|
| 126:19 | that's that's what these hurricanes do. . Alright, so we went from |
|
| 126:26 | on the upper left to this. , you see what I'm saying That's |
|
| 126:32 | hurricane. That's a major hurricane Alright, and then I told you |
|
| 126:36 | what happens off the leeward margin? spit. Alright, this is uh |
|
| 126:41 | is recovery. This is two years West Spit recovered from Ike Ike pushed |
|
| 126:46 | spin all the way into the basin years of recovery when this photo was |
|
| 126:53 | . And then you can see what after Irma Irma did the same |
|
| 126:57 | pushed all that carbonate sand. and then these things also cut these |
|
| 127:03 | . Donna did this. I did . All right. I made the |
|
| 127:09 | cut. That was right here. then you can see the I cut |
|
| 127:13 | here in 2020 15. So, is seven years after the hurricane starting |
|
| 127:19 | fill back in, right because of active sand deposition and sort of longshore |
|
| 127:25 | . And then Irma came through and that cut and just widened it by |
|
| 127:30 | or threefold. Okay, A difference what? 20 miles an hour, |
|
| 127:36 | miles an hour in terms of wind , erodes it even more. |
|
| 127:44 | Alright, so, I just want appreciate, you know, hurricane is |
|
| 127:48 | important part of the story. You need hurricanes to break up |
|
| 127:53 | You need hurricanes to move sand bodies the northern Bahamas because tidal currents don't |
|
| 128:00 | them around, but on a windy that the trade winds will move |
|
| 128:04 | but hurricanes will move it even Okay, so keep that in |
|
| 128:10 | Alright, let's take a It's about . Let's take a 10 minute break |
|
| 128:15 | we'll come back and talk about the ramp model. Okay, okay, |
|
| 128:25 | we've what we've done so far this as we've talked about these modern carbonate |
|
| 128:32 | . Right? We started out of just talking about the individual environments of |
|
| 128:37 | to give you a feel for the and processes, scales, things like |
|
| 128:42 | . And then I put everything together terms of the End Member model for |
|
| 128:48 | state margin platform system. And I you a variation on the theme depending |
|
| 128:53 | your physique graphic setting. So when you get into a stronger trade winds |
|
| 128:58 | , easterly trade winds system that changes game a little bit. And that's |
|
| 129:02 | you have to always understand where your of interest was relative to the paleo |
|
| 129:08 | . The other End Member model is carbonate ramp model and this is a |
|
| 129:12 | of classical cartoon that everybody uses to this deposition model. Again, what |
|
| 129:19 | bottle says is that the Uh slope by by definition is one degree or |
|
| 129:28 | . What that means is that you off an older landmass. It's imperceptible |
|
| 129:32 | in water depth as you go from out into a deeper water basin, |
|
| 129:37 | in this model. The basin is that deep. It can't be that |
|
| 129:41 | . It's on the scale of tens meters like the example, we're going |
|
| 129:46 | talk about from the Arabian gulf is m of water depth to generally no |
|
| 129:51 | than a few 100 m of water . And so nothing near the depths |
|
| 129:56 | we talked about for the caribbean and where you get, you know, |
|
| 130:00 | of potentially thousands of meters of water . Okay, so in this low |
|
| 130:06 | profile, there's no platform margin. ? It's a ramp. The focus |
|
| 130:12 | high energy is closer to shore This is where tidal currents or wind |
|
| 130:19 | agitation impinges on that shallow water The net effect usually is to develop |
|
| 130:26 | sand. You don't have the right of energy for for making good |
|
| 130:31 | So, you're not gonna get barry associated with the ramp model. |
|
| 130:35 | If you get any kind of research going to be isolated and it's gonna |
|
| 130:39 | taking advantage of pre existing topography. that usually means that because of |
|
| 130:44 | Usually, what we see as carbonate , politic or skeletal or a mixture |
|
| 130:49 | both respond to that persistent agitation on sea floor and then the trade winds |
|
| 130:56 | the tropical subtropical setting will do what will splay this stuff out. Will |
|
| 131:00 | up longshore currents that will lead to of the linear barrier islands. And |
|
| 131:06 | you can do that, then you a restricted lagoon behind the barrier |
|
| 131:10 | And those sediments can feed a beach tidal flat, shown by the |
|
| 131:15 | Okay. And then progressively deeper and . Once you get down below a |
|
| 131:22 | of about 20 m, what do start to pick up in that deeper |
|
| 131:26 | setting? You start to pick up pelagic microfossils. Okay. The |
|
| 131:31 | as I said, can't live shallower about 15 or 20 m. The |
|
| 131:37 | will be out there, coconuts can live in shallow water too. So |
|
| 131:40 | not unique deepwater indicator. But the foraminifera are okay, so the famous |
|
| 131:48 | the only good analog we have modern we have for carbonate ramp is the |
|
| 131:54 | called Arabian gulf. Right? Which what you call it when you teach |
|
| 132:00 | abu Dhabi side. And I guess you talk for the Iranians, you |
|
| 132:05 | it the Persian gulf, right? they call it the Persian gulf. |
|
| 132:08 | I think in the literature is pretty established now to be called the Arabian |
|
| 132:13 | . And this is the Arabian it's just isolated uh basin and it |
|
| 132:21 | bounded on the north east side by Zagros mountains of Iran. And then |
|
| 132:30 | Tigris Euphrates river up here in Iraq Arabia. The United Arab Emirates States |
|
| 132:36 | down here. And the whole thing isolated by the straits of Hormuz. |
|
| 132:42 | . And you can see the setting were subtropical were 24, north of |
|
| 132:46 | equator. This is basically the same as the Northern Bahamas that we just |
|
| 132:52 | about. So what are going to the drivers for carbonate deposition first? |
|
| 133:02 | driver would be tidal currents because when constrict flow in and out of this |
|
| 133:07 | from the indian ocean, you do some tidal current effect. The tide |
|
| 133:14 | From the times I've been to Abu , you can see the tide ranges |
|
| 133:18 | two m. Okay, so it's little bit higher tide range than I |
|
| 133:21 | you for the Caribbean. So when change that water level, you're going |
|
| 133:25 | get some tidal current effect. The other driver, there's no |
|
| 133:33 | any other oceanic driver here. There's no oceanic swells that come into |
|
| 133:36 | basin. Uh, so the other are what are called seasonal shamal |
|
| 133:43 | These are winds that are generated up the northwest in southern europe, in |
|
| 133:49 | mountains. Right? These are winds up by pressure difference is sort of |
|
| 133:52 | the santa ana winds in California, ? That blow through san Diego. |
|
| 134:00 | these winds blow to the southeast. . And they blow mostly during the |
|
| 134:06 | but they can blow any time during year. And they are they usually |
|
| 134:11 | for less than 50 mph, but are recorded Velocities of over 70°, which |
|
| 134:18 | almost hurricane strength. Okay. And , most of you are probably too |
|
| 134:25 | to to remember desert storm the first war, But back in the late |
|
| 134:31 | , they were really concerned about no desert conditions related to these winds. |
|
| 134:38 | ? The strong winds would create these and they were, that was caused |
|
| 134:43 | the chamalla winds. Okay, so a driver and then potentially uh you |
|
| 134:51 | to appreciate there's no recorded history of hurricane or typhoon coming into this basin |
|
| 134:57 | the eye of the storm actually comes the basin. Now you can have |
|
| 135:01 | I sit over here right, I still have a dramatic effect on this |
|
| 135:06 | . But no recorded history of major coming into this basin. But about |
|
| 135:12 | or six years ago there was a published on this other phenomena called mateo |
|
| 135:18 | . These are meteorologically driven tsunamis that probably related to big storms that come |
|
| 135:25 | to the basin, but don't come the basin. Alright, so I'll |
|
| 135:29 | about those and what effect they have a minute. Okay, so that's |
|
| 135:35 | general setting. Where is the area carbonate? The interest that we're going |
|
| 135:40 | talk about is down here in the part of the basin facing to the |
|
| 135:45 | . Right, so areas like Abu and Dubai where you get shallow water |
|
| 135:51 | deposition, they're going to face into stronger shamal winds coming out of the |
|
| 135:55 | quadrant. Okay, and so you the three sedimentary provinces here, the |
|
| 136:02 | is shallow water carbonate and evaporate The brown is the system of the |
|
| 136:10 | Euphrates River and then the gray is marine, deeper marine. This is |
|
| 136:16 | you get 70 80 m of water and it's a mixture of carbonated, |
|
| 136:21 | material. The carbonate is pelagic The fine grained classics are coming out |
|
| 136:26 | the Zagros Mountains by by flooding. . And so those are the three |
|
| 136:35 | provinces. So when you look at symmetry in the southern part of the |
|
| 136:42 | of the basin, this is abu again, one of the United Arab |
|
| 136:47 | states. Look at the contours here the water depth, gradual imperceptible change |
|
| 136:53 | water depth out toward the base, it really is a good modern analog |
|
| 136:57 | a ramp. Okay, but look deep the base it doesn't get. |
|
| 137:02 | 40 fathoms. Okay, so multiply by six to get ft as 240 |
|
| 137:11 | Or about 80 m of water That's not very deep for a |
|
| 137:14 | Okay. But that's normally the case these ramps. They're not attached to |
|
| 137:19 | deep water basins. Okay. And I said, we don't normally associate |
|
| 137:26 | with the ramp model and certainly don't barrier reefs. If you're going to |
|
| 137:29 | any kind of briefing, it's gonna either closer to the shore line where |
|
| 137:33 | have pre existing topography and you're gonna some of this for this area or |
|
| 137:38 | going to be further offshore where there's bottom topography that exists. And so |
|
| 137:44 | see a number of these enclosed contours offshore. These are reefs, isolated |
|
| 137:52 | sitting on salt punch up structures. , this part of the world has |
|
| 137:56 | an actively tectonic salt basin going back the Permian. And uh so salt |
|
| 138:03 | right, salt punches up the sea sometimes creates topography. You can put |
|
| 138:08 | refill with sand body on top of . And then what could happen to |
|
| 138:12 | ? It can withdraw, right? you actually can take what you can |
|
| 138:16 | this and do what this right, , inverting. Right? Make a |
|
| 138:23 | and where you have high energy but now it's a low. |
|
| 138:29 | and you'll see examples of this next . All right, But I want |
|
| 138:32 | to appreciate that you can have reefs with the ramp model, but it |
|
| 138:36 | to be because of pre existing topography essentially send deposition topography related to something |
|
| 138:43 | salt tectonics. Alright, okay. the classical ramp model that people apply |
|
| 138:50 | the rock record is the one on bottom here where we come out of |
|
| 138:54 | water, we gradually shallow up toward land mass. Close to the land |
|
| 138:59 | , we create these high energy brain , if they build up above sea |
|
| 139:05 | to make an island, then we a restricted lagoon behind it. |
|
| 139:10 | the brown and then that can feed beach or tidal flat on the on |
|
| 139:13 | other side. Alright, so, is, this is the classical |
|
| 139:19 | Again, this is Bruce purser was geologist with Shell's international group out of |
|
| 139:25 | Hague. And uh back then, know, we didn't use the term |
|
| 139:31 | , You light and stable light. what he mapped as carbonate sand is |
|
| 139:37 | active analytic sand. Okay. What mapped his compound brain is what pretty |
|
| 139:44 | grape stone. And this is what call the stabilized dualistic settlement. |
|
| 139:50 | So oranges, this stable yellow is active and then progressively more and more |
|
| 139:56 | critic and more adulation as you go deeper water. Again, remember the |
|
| 140:00 | delicious material doesn't have to be It's there here because the stuff being |
|
| 140:06 | off of the Iranian side of the from the Zagros Mountains. Okay. |
|
| 140:12 | don't assume every time you go into carbonate ramp basin that is going to |
|
| 140:17 | modulations. It all depends on whether a source for the clay or |
|
| 140:21 | Okay. Okay, so let's take look at this model and I'll show |
|
| 140:25 | how it's put together. I'll show what the sediments look like. |
|
| 140:28 | So there's other terminology that's come into to characterize position along the ramp |
|
| 140:36 | Alright, so basin is the deepest of the ramp down the the end |
|
| 140:42 | the slope. Right? That's the water basin. Generally not more than |
|
| 140:46 | few 100 m of water depth at most. And then people take the |
|
| 140:51 | itself and they subdivided into an outer and the inner ramp. And what's |
|
| 140:57 | line of demarcation, it's about 15 20 m of water depth. Where |
|
| 141:03 | than that you have pelagic carbonate deposition where your shallower than that. You |
|
| 141:08 | get pelagic micro fossil deposition. We're talking about the foraminifera again, |
|
| 141:14 | , Those little glow bos single cell that live in the upper part of |
|
| 141:20 | water column, but not right at surface. All right, so you |
|
| 141:23 | them deeper than 15 or 20 but you don't find them back |
|
| 141:28 | Okay. And so you can see we're going to start down here and |
|
| 141:33 | the deeper part of the basin or outer, deeper part of the outer |
|
| 141:38 | where you get that mixed articulations, micro fossil, wacky stone like mud |
|
| 141:43 | . Then we're gonna come up we out the articulations material as we get |
|
| 141:47 | from the Iranian side of the but we still dominated by planking |
|
| 141:53 | Then, when we get shallower we drop out the planking microfossils. |
|
| 141:58 | evolve into more of an open skilled, employable Blackistone pack stone and |
|
| 142:05 | closer to shore line where it's higher where tidal currents impinge on that shallow |
|
| 142:12 | . That's where we get our complex maybe fringing reefs, That there's pre |
|
| 142:18 | topography. The net effect is to up the sea level create an isolated |
|
| 142:24 | lagoon back here with the restricted fauna then a tidal flat on the other |
|
| 142:31 | with evaporates because it's a dry, arid climate. Okay, so the |
|
| 142:39 | core here is from the deepest part the ramp profile. This is pretty |
|
| 142:44 | of color. The greenish gray color a reflection again of the mixture of |
|
| 142:49 | delicious material with these fine grained pelagic by exacerbated. These are oxidation features |
|
| 142:57 | to the burrowing activity. Alright, there's no preservation stratification here. And |
|
| 143:03 | will be preserved as a pelagic micro wacky stone or lime mud stone, |
|
| 143:10 | on Whether you have more than 10% the sand sized grains or not. |
|
| 143:15 | , so that's what the deepest part the profile looks like. That would |
|
| 143:19 | down here. When you come up ramp, get away from the Zagros |
|
| 143:24 | . You have the same kind of but without the clay material. |
|
| 143:29 | so it would still be burrowed pelagic fossil Blackistone two pac stone. |
|
| 143:38 | And then once you get shallower than 15-20 m, you see a change |
|
| 143:42 | the character of the sediment. It's my critic. It's below fair weather |
|
| 143:46 | based. So there's deposition of right? Its bite debated. So |
|
| 143:50 | political fabric. But there's a more scalable fabric here. There's no plastic |
|
| 143:58 | anymore. So it's a it's things a kind of terms and calculus screaming |
|
| 144:03 | molluscs for em and effort. Remember higher diversity means better circulation a |
|
| 144:09 | bit shallower water. All right, still pretty MMA critic and can be |
|
| 144:15 | as mostly a pack stone. Sometimes wacky stone. Alright. So it's |
|
| 144:20 | not good reservoir potential here. what can happen in the setting? |
|
| 144:26 | can happen in the setting is when and a little bit deeper water where |
|
| 144:31 | have that kind of deposition? If pauses in deposition, if there are |
|
| 144:37 | periods of non deposition on the sea , this is a setting where you |
|
| 144:41 | start to get marine segmentation, but a different expression of marines invitation than |
|
| 144:47 | I talked about yesterday that occurred in high energy conditions. Right? This |
|
| 144:52 | taking advantage of stuff not being deposited the sea floor and letting time slowly |
|
| 144:58 | seawater through these sediments. When you that underwater, you produce these |
|
| 145:05 | more regionally extensive cemented layers separated by material. So the story here is |
|
| 145:13 | where you have the segmentation, You pauses and deposition long enough to slowly |
|
| 145:19 | seawater through the sediment and cemented and you have unconsolidated sediment which washed out |
|
| 145:24 | this photograph, that would be higher of deposition. Okay, In other |
|
| 145:29 | , you were rapidly burying the you couldn't submit it. Everybody understand |
|
| 145:34 | I'm saying. So, these are more extensive regional hard grounds than what |
|
| 145:38 | showed you in the Bahamas yesterday where very patchy and distribution because you couldn't |
|
| 145:44 | couldn't stabilize the whole active. Was Right? So you just got patchy |
|
| 145:49 | to those hard grounds. Okay, the cement are identical to what I |
|
| 145:54 | you for the Bahamas yesterday. Fibrous or agonized cements packets around the |
|
| 146:01 | Alright. And then when they get the hard grounds get broken up, |
|
| 146:04 | also get the lumps again. This a great stone like fabric we talked |
|
| 146:08 | before they will be associated with some this. Okay. And then we |
|
| 146:14 | up closest to the shore line where strong tidal currents impinge on the profile |
|
| 146:21 | in part this takes advantage of the existing topography and this is where you |
|
| 146:26 | to form the analytics sands. Okay you have to appreciate that there is |
|
| 146:31 | pre existing topography here that was there holocene carbonate deposition. Right? Abu |
|
| 146:41 | is built on some of these older . Summer pleistocene summer, tertiary |
|
| 146:46 | Okay. And you can see there between some of these islands and when |
|
| 146:51 | try to push water through these as we talked about yesterday, what |
|
| 146:55 | to the tidal current velocities? They up right as you're trying to force |
|
| 147:00 | through a narrow cut. And so that strong tidal current agitation that people |
|
| 147:07 | is where the U. S. forming. So if you look at |
|
| 147:09 | the U. S. And distribution the on the shallow part of his |
|
| 147:14 | which in this model is called the crest. Where do these words occur |
|
| 147:20 | the mouse of these channels. Alright. So people think the |
|
| 147:24 | S. Are forming in the channels the stronger tidal current agitation and then |
|
| 147:31 | pulled off shore as what we call delta features. And then the trade |
|
| 147:37 | do what they push them sideways by currents to create the barrier islands that |
|
| 147:42 | going to show you. And so net effect of the pre existing |
|
| 147:47 | you can see the tertiary islands are , the light brown color would be |
|
| 147:54 | the net effect of the Pleistocene holocene . Is to do what to create |
|
| 148:00 | a barrier or write to create a off the lagoon behind it to create |
|
| 148:06 | restricted isolated lagoon. Alright, and then whenever you have exposed highland |
|
| 148:13 | in front of some of these older , you get a little bit of |
|
| 148:17 | here, but it's these isolated fringing complexes. Okay, everybody appreciate what |
|
| 148:22 | saying. So the ramp crest is focus of high energy taking advantage of |
|
| 148:27 | existing topography. Most of that high is expressed by sand development. But |
|
| 148:33 | there is some exposed older island you can get small little fringing reefs |
|
| 148:39 | . All right, so here's the photograph that shows you this relationship. |
|
| 148:47 | , older island and you can see cuts between the islands here. This |
|
| 148:51 | where people think you're making the fluids the strong tidal current agitation, the |
|
| 148:57 | gets pulled off shore as tidal deltas then distributed laterally by uh the trade |
|
| 149:05 | to set up the barrier islands. , so if you back off on |
|
| 149:10 | , you see this relationship here channel offshore, deeper marine, again, |
|
| 149:17 | to closer to the shallow part of profile. This is where you make |
|
| 149:21 | you is that gets played out by currents that get fed into this barrier |
|
| 149:26 | succession. You still have the active stable components that we talked about |
|
| 149:32 | Same attributes that we talked about for Bahamas you see here. Okay, |
|
| 149:38 | distribution of you is is different. ? It's just spread out by the |
|
| 149:43 | currents and longshore currents are always set by prevailing winds hitting the shore line |
|
| 149:49 | an angle. Right? That's how set up the long shore longshore currents |
|
| 149:53 | move this carbonate sand. Okay, . Alright, so this guy's in |
|
| 150:00 | lagoon looking seaward to give you a for the, the relief of these |
|
| 150:05 | politic sand islands are not that high they are analytic. This is what |
|
| 150:14 | sentiment looks like in thin section, USSR rag genetic. The coatings are |
|
| 150:18 | classical tangential originating goods. But what's here? Anybody know what these white |
|
| 150:27 | are as nuclei. And then section grains. Great bye. Resurgence. |
|
| 150:36 | of the mineral courts. That's Okay, where's quartz coming from? |
|
| 150:44 | coming from land? It's coming from abu Dhabi side or the Saudi Arabian |
|
| 150:51 | of the Arabian gulf. Excuse quartz sand is being pushed as big |
|
| 151:06 | right to the edge of the basin then the stuff gets blown in to |
|
| 151:11 | Arabian gulf and some of it you'll gets incorporated into the lagoon or tidal |
|
| 151:17 | . Some of this actually works. way offshore and gets tied up in |
|
| 151:20 | sand body system. Okay, so is very common to see in the |
|
| 151:25 | record when you deal with the with that are associated with ramps, |
|
| 151:29 | Because they're developed closer to the shore . And in fact, I think |
|
| 151:33 | the rock record when you see ASU material with a lot of courts |
|
| 151:39 | it probably suggests that you're associated with ramp model where the US sands form |
|
| 151:44 | to that paleo shoreline. Alright, right. Remember who is Can the |
|
| 151:49 | can be anything from a court's crane appeal Lloyd to skeletal particle to a |
|
| 151:55 | of volcanic plastic material. Right. , everybody appreciate the relationship. |
|
| 152:01 | so, again, coming back to map the net effect of the US |
|
| 152:06 | deposition and displaying out of that to barrier islands in concert with the older |
|
| 152:12 | and the fringing reefs creates what we the ram crest that isolates the lagoon |
|
| 152:19 | it. Okay, so the title do cut back into the lagoon. |
|
| 152:25 | still don't get the impression this is big evaporated zinc. It's not All |
|
| 152:29 | . There's no evaporates in this lagoon . It's but it's it's more restricted |
|
| 152:35 | right? Because you have a little , you have poor circulation. You |
|
| 152:39 | elevated salinity, but you don't have salinity. And so we're gonna take |
|
| 152:44 | look at the laguna sediment. And then we'll contrast that with the |
|
| 152:49 | flat, which locally is called the in this part of the of the |
|
| 152:54 | . All right, So what's uh you see here with the color pattern |
|
| 153:01 | in the lagoon is very complicated. ? So let me let me relate |
|
| 153:05 | color patterns to what we talked about the Bahamas. Alright, so the |
|
| 153:12 | brown Bruce purser called this a four gaster pod carbonate mud, essentially the |
|
| 153:21 | brown that you see here is equivalent the soft color lime muds we talked |
|
| 153:26 | on great bahama Bank. Okay, little bit more restricted. Less |
|
| 153:31 | Alright. And then the orange that see here, he called it pellet |
|
| 153:36 | . That's the old term for what use now for pill Lloyd. |
|
| 153:40 | These are basically burrowed hard palate sands a muddy matrix. Ok. That |
|
| 153:49 | be the light orange and then the . The dark green here in the |
|
| 153:54 | is where you get the sign of mats, you now know where they |
|
| 153:58 | , right? They don't live They would be eaten by gastro |
|
| 154:03 | They represent inter title to super title . So, to get the green |
|
| 154:10 | here in the lagoon. What did have to do, You had to |
|
| 154:13 | an island. Okay. Storm had throw up an island and then around |
|
| 154:18 | island you get the cyanobacteria maps. , so that's where the green comes |
|
| 154:23 | in the lagoon. All right, let's take a look at the sediment |
|
| 154:29 | in core. Both the soft heart color stuff look like this. |
|
| 154:35 | , no stratification. So, you this color modeling, We take that |
|
| 154:40 | be again, a byproduct of by . Right? So it's burrowed. |
|
| 154:45 | then what are the fauna? These the gastro pods? The high spired |
|
| 154:49 | pods. And there are five valves their foraminifera. Alright. Both of |
|
| 154:59 | orange and dark brown that I The previous map looked like this at |
|
| 155:03 | . But here's the difference in thin . The heart fellas stuff looks like |
|
| 155:07 | in thin section where you see the chambered dark MMA critic Foraminifera. You |
|
| 155:13 | the plate bible fragments, You see gaster pods that I just showed |
|
| 155:18 | And then look at the sediment here colloidal well preserved colloidal fabric. |
|
| 155:24 | These are the hardened fecal pellets that talked about. But in the rock |
|
| 155:28 | we're going to call these p Okay, so you can see how |
|
| 155:32 | is going to preserve. This is be a skeletal colloidal tak stone, |
|
| 155:37 | tax stone fabric. Right? probably high mud pack stone. |
|
| 155:41 | A lot of mud, but distinctly stone texture. Okay, restricted |
|
| 155:47 | Just a few species of forums, species of malice. Okay, contrast |
|
| 155:56 | with the soft colored stuff. You see the same fauna. So the |
|
| 156:03 | and the little benthic foraminifera, you some distinct colloidal fabric here, but |
|
| 156:09 | you sort of get the sense that are starting to squish back into the |
|
| 156:13 | line mud. Right? There's a proportion of the softer fecal pellets. |
|
| 156:18 | this is going to be preserved as of a vague colloidal wacky stone to |
|
| 156:23 | skeletal colloidal, wacky stone to Okay, everybody appreciate that. All |
|
| 156:29 | . And you saw if you go to the map, right, you |
|
| 156:32 | a lot of variability here again, has to do with circulation within the |
|
| 156:38 | . And some of that's probably influenced proximity to the to the title |
|
| 156:44 | Alright, okay, so let's finish with the last part of the story |
|
| 156:51 | for the ramp model, which on landward side is a tidal flat. |
|
| 156:55 | locally the Arabs call these evaporated tidal . Sakas, okay. And you |
|
| 157:02 | see the transition on this google photograph the burrowed colloidal fabric we just talked |
|
| 157:08 | in the lagoon. The title channels out when you see the change from |
|
| 157:19 | light colored burrowed and effectively grazed tribunal raised by the gaster pods again and |
|
| 157:27 | a change into the black cyanobacteria That's roughly the lower intertidal zone that |
|
| 157:33 | talked about before. I'm sorry, intertidal zone. Right. So this |
|
| 157:38 | be lower intertidal. The sub subtitle underwater for most of the title cycle |
|
| 157:45 | burrowed effectively grazed intertidal zone out of . The only thing that can live |
|
| 157:51 | sign of bacteria and then the true own would be the Saka back |
|
| 157:56 | Okay. And this is some of classic material coming in from the other |
|
| 158:01 | . Some of that classic material is start to mix with these tidal flat |
|
| 158:06 | with the lagoon and actually make itself it make itself get itself further offshore |
|
| 158:13 | even get tied up in the analytic . All right, so what are |
|
| 158:17 | drivers here for title flat deposition to carbonate deposits up here in the intertidal |
|
| 158:23 | Sokka, you have to deliver sediments the lagoon or from something further |
|
| 158:29 | Okay, so there's no winter storms . Okay, you're only left with |
|
| 158:37 | two drivers. The shamal winds. the orientation here? This face is |
|
| 158:42 | the northwest. So this could catch stronger shamal winds or it's the influence |
|
| 158:47 | those mateo tsunamis. Okay. And is what the photograph that was published |
|
| 158:55 | and this is 2017 when this paper out, sort of interesting that uh |
|
| 159:00 | document these recurring wave systems that that some of the coastlines in the Arabian |
|
| 159:07 | after one of these major low pressure probably related to to a tropical storm |
|
| 159:14 | feature or an offshore hurricane. And things you can see, you |
|
| 159:20 | they're 3, 4 ft high. pound the shore line, right? |
|
| 159:24 | is how you would erode offshore, stuff in suspension and then deliver it |
|
| 159:28 | onto the tidal flat. Okay, that's one mechanism. All right. |
|
| 159:34 | then the other mechanism would be the all wins. All right. And |
|
| 159:40 | time I had a chance to to these tidal flats a long time |
|
| 159:44 | I went to abu Dhabi and got field trip, got a field trip |
|
| 159:51 | by some of the locals. They us out for a day to to |
|
| 159:55 | at the title flat and they, local geologist told us that the shamal |
|
| 160:02 | when the winds blow, they come very quickly. Right? And they |
|
| 160:06 | sometimes 50, mph. And what do is they also blow a wall |
|
| 160:12 | water up onto the tidal flat and water level comes up so quickly that |
|
| 160:19 | like camels, even people drown out the tidal flat. All right, |
|
| 160:24 | wall, the water comes up. I envision that chamomile wind effect might |
|
| 160:29 | something like this as well. And this would be what delivers settlement |
|
| 160:34 | the lagoon even can deliver sediment from analytics sand body system offshore because we |
|
| 160:42 | cores on the tidal flat and we found stringers that will expand in some |
|
| 160:48 | that title flat sediment. So even even the sand gets pushed back through |
|
| 160:54 | lagoon into that into that title Okay, alright, So let's just |
|
| 161:00 | up by taking a look at some the attributes of the three components that |
|
| 161:04 | up this evaporating title flat. We're onto land, right? We have |
|
| 161:10 | toes in the lagoon. Alright. light area out of water is the |
|
| 161:15 | intertidal zone. Again, the only that can really live there is it's |
|
| 161:21 | few restricted species of gaster pods and and forums you see it's effectively grazed |
|
| 161:29 | free of the black cyanobacteria mat by gaster pods. Then the black belt |
|
| 161:34 | the upper intertidal zone to restricted for to live there except for the santa |
|
| 161:41 | . And then in the distance you the wider zone, that's the true |
|
| 161:45 | title uh Environment. Alright. So is what the cyanobacteria mats look |
|
| 161:52 | It's a different type of map than I showed you for Caicos and |
|
| 161:58 | right? That was the toughest spongy here. It's more of a low |
|
| 162:03 | . A little bumpy kind of Alright. And uh but it's the |
|
| 162:10 | principle, right? It's just a type of sand of bacteria. They're |
|
| 162:15 | because nothing else can live here. . They get paid by marine water |
|
| 162:20 | it's too restrictive for borrowers to restricted for grazers or other kinds of organisms |
|
| 162:25 | live there. And so when you the sediment, you see the kind |
|
| 162:30 | fabric that I showed you for the algo marsh in the Bahamas, |
|
| 162:35 | The classical centimeter scale stratification where you from the darker layers which represent the |
|
| 162:42 | bacteria to the storm derived layers brought either by shamal winds or by the |
|
| 162:48 | tsunamis. Okay. And it just over and over again. So this |
|
| 162:53 | of stratification is comparable to what I you in the Bahamas for keiko's and |
|
| 163:00 | . But there's a difference here, ? The climate remember on Bahamas, |
|
| 163:06 | keiko's and Andrew's, there's no evaporates these sediments. Okay, there's a |
|
| 163:13 | bit of gypsum and some of the , crisp crust on keiko's and that |
|
| 163:17 | it. But here, this is much drier climate. So in this |
|
| 163:22 | , we start precipitating out to evaporate . And the first mineral is |
|
| 163:28 | proto dolomite actually precipitates in the It's not replacing anything. It's just |
|
| 163:34 | micro crystals of dolomite that precipitate. the first thing that comes out of |
|
| 163:39 | seawater. Okay, and then what behind it is the gypsum that you |
|
| 163:44 | here. So gypsum is calcium sulfate with water. Right? So it's |
|
| 163:50 | hydrated form of calcium sulfate. And and hide right here because it's too |
|
| 163:56 | wedded. You have to have drier for an hydrate. Okay, so |
|
| 164:02 | like this in the Bahamas. But pretty common because of the drier |
|
| 164:07 | And look what it's doing to the structures. It's obliterating the sedimentary |
|
| 164:12 | Okay, okay, so that's the the intertidal santa bacteria matt environment everybody |
|
| 164:27 | that. And then the true which means above being high tide would |
|
| 164:31 | see water when you get the chamomile mateo tsunami wave effects is what we |
|
| 164:39 | the Sokka. Alright. And so light brown color you see here is |
|
| 164:46 | . It's a mixture of carbonate coming the Laguna side and fine grained classics |
|
| 164:51 | clay coming from the landward side. term several exposure. Right, mud |
|
| 164:58 | start to see the big political mud and these are much bigger scale mud |
|
| 165:04 | than what I showed you on the of andrews. And you can see |
|
| 165:09 | coming here. You see the trenches dug here, you start to pick |
|
| 165:13 | and hydrates. Okay, so if think it's deep enough trench, you |
|
| 165:18 | see this first thing is the color the sediment that's sort of reddish brown |
|
| 165:23 | is pretty diagnostic of this fix of and plastic materials. So there's fine |
|
| 165:32 | regulations material mixed in. They're actually disk oiled crystals of gypsum, the |
|
| 165:39 | in this stuff. There's still dolomite precipitates in the stuff. Okay, |
|
| 165:44 | crystals of dolomite. But then I the spectacular fabric is the and |
|
| 165:50 | The white crystals of anhydride start off isolated little nodules. The nodules coalesce |
|
| 165:58 | these layers that people call bedded Nagy and hydrate. And then the nod |
|
| 166:04 | layers of dodgeball and hydrate coalesce into people call, not regular mosaic and |
|
| 166:11 | . Okay. And what's the common in the rock record? Chicken wire |
|
| 166:16 | Heidrich. So if you if you the the wire they use on chicken |
|
| 166:23 | , right with the holes. Chicken wire, just envision filling those holes |
|
| 166:28 | nodules of and hydrate. That's where name comes from. Okay, So |
|
| 166:33 | can appreciate, you know, when is first documented back in the |
|
| 166:39 | people saw this, everybody ran back the rock record and all these Nagy |
|
| 166:44 | and hydrate sequences, evaporating sequences were reinterpreted the title flag, evaporating tidal |
|
| 166:53 | , including many based on evaporate Because this fabric is not unique to |
|
| 166:58 | flat. It can form in any . Okay, By replacement or by |
|
| 167:05 | . These are displacing. Okay, they precipitate in the sediment and they |
|
| 167:10 | out and displace the sediment. Now, in the literature, everybody |
|
| 167:15 | show you a picture that looks like and say, this is typical. |
|
| 167:22 | me, This is typical of evaporated flat. That's abu Dhabi tidal |
|
| 167:28 | Okay, but what doesn't come out the variability you see along the strike |
|
| 167:35 | the Saka. So I told you we were there, we dug three |
|
| 167:40 | trenches along the strike over about a spacing. Okay. And one of |
|
| 167:46 | looked just like this. Okay. two of them had No and hydrate |
|
| 167:51 | all. Okay, so that doesn't out in the literature. Right. |
|
| 167:55 | tend to simplify things in the literature to make it less variable. |
|
| 168:02 | variability is not good. Right? models, right? You want you |
|
| 168:07 | things to be simple, but you to appreciate that there's a lot of |
|
| 168:12 | here in terms of an hydrate Okay, So to summarize, if |
|
| 168:20 | were to go back, go to Dhabi and dig dig deep enough trench |
|
| 168:24 | you go down two or three m you dig a take a core. |
|
| 168:28 | is what you would see, you see at the base stuff that looks |
|
| 168:33 | the Laguna settlement today. Uh scalable to Pakistan, Pakistan with a restricted |
|
| 168:39 | burrowed, breaking up into a intertidal with the crypto travel lamination, the |
|
| 168:46 | mats, and storm layers with some of dolomite and gypsum. Displacing, |
|
| 168:53 | some of that stratification Grading up into more brownish colored fabric. A mix |
|
| 169:00 | carbonates and plastics with gypsum precipitation, and hydrate and Angela Knight. |
|
| 169:07 | so what's happening here? What's causing vertical succession? Anybody know what we |
|
| 169:16 | this? When we go from a bit deeper subtitle carbonate to a |
|
| 169:22 | we call this upward shoaling. this is what carbonate successions do through |
|
| 169:29 | with time, with substance? With gradation, they build upward. |
|
| 169:35 | And so this is a vertical That's been created by these tidal flats |
|
| 169:42 | the sea level and then doing Pro grading seaward over the more offshore |
|
| 169:51 | lagoon. Right? That's how you this vertical succession. All right. |
|
| 169:56 | then the concept is related to what's Walters law. I don't know if |
|
| 170:02 | ever heard walter's Law. So you're hear it later. Alright. |
|
| 170:07 | Walter's law has been around for yeah, 30 years. Okay. |
|
| 170:15 | back to 1800 and Walters law says want to do what they want to |
|
| 170:23 | up and once they get the sea , they don't want to be above |
|
| 170:26 | level. So they want to pro in the seaward direction. So, |
|
| 170:30 | pro grade the more landward faces builds over the more seaward faces through time |
|
| 170:36 | produce a vertical succession that looks like . Okay, that's walter's law. |
|
| 170:42 | , walther's law doesn't work everywhere. reasons we'll talk about later, but |
|
| 170:47 | just want you to appreciate it works . Okay. And look at the |
|
| 170:50 | appropriation for abu Dhabi remember 802,800 ft m. I'm sorry. For 1000 |
|
| 170:59 | for parts of Andrew's here. It's greater a kilometer per 1000 years or |
|
| 171:07 | meter per year. Okay. Which not surprising, right? Because you've |
|
| 171:11 | a low relief slope. It doesn't much to build up and shoot it |
|
| 171:16 | in the seaward direction. Okay, these carbonate ramps. Okay. Where |
|
| 171:22 | they tend to occur geologically during those periods where he had little or no |
|
| 171:27 | topography. They also that tends to associated more with these isolated interpret tonic |
|
| 171:37 | or it occurs during geological time periods we didn't have good shallow water, |
|
| 171:41 | energy reef farmers. Right. Didn't the organisms to do that. |
|
| 171:48 | think back to that diagram. I you yesterday at the end of our |
|
| 171:52 | lecture where I showed you how the reforming organisms changed through time. |
|
| 171:58 | Right. Therefore perhaps are limited to geological time periods. They are more |
|
| 172:05 | in these restricted what we call intricate basil sags. They would also |
|
| 172:13 | Excuse me. I didn't sleep very last night. They occur in temperate |
|
| 172:18 | . Cool water climates. Okay. I told you we're not talking about |
|
| 172:24 | water climates in this segment, but the kind of stuff you get off |
|
| 172:28 | New Zealand and Australia. Today, are ramps. Okay, then drop |
|
| 172:34 | into a really deep water base and but there's no riffing associated with with |
|
| 172:41 | ramps. Everything is is as cool cal citic related deposition organisms that can't |
|
| 172:49 | topography. Okay, so you would ramps with the cool water climates. |
|
| 172:55 | . And I just want to finish by showing you, I showed you |
|
| 172:58 | famous abu Dhabi example where you see narrow belt of tidal flat deposition, |
|
| 173:03 | ? That parallels the margin of the runs parallel to the margin of |
|
| 173:08 | I want you to appreciate that the can be a much greater areal |
|
| 173:14 | Alright, there that stopped. It just a few kilometers wide. |
|
| 173:19 | but I want to show you this still in the same basin. This |
|
| 173:23 | the peninsula cutter. Right. And , you know, this is up |
|
| 173:31 | the north west from Abu Dhabi where were. And on this side of |
|
| 173:37 | Dhabi, there are major Sakas that well into the into the into the |
|
| 173:45 | . So that's a scale bar of kilometers. So that's 5, 10 |
|
| 173:50 | , almost 20 kilometers all this white you see here is part of the |
|
| 173:56 | just means that it's water that comes right? Every title cycle and goes |
|
| 174:01 | out, right. Is delivered by title exchange and the sediments that are |
|
| 174:07 | have to either have to be thrown by storms if there's carbonate sediment. |
|
| 174:13 | most of the settlements are back here just evaporated, right? Because you've |
|
| 174:17 | the exchange of seawater and then you've really hot climate. Right? And |
|
| 174:23 | evaporation. Alright, so the climate get hot and I was there, |
|
| 174:30 | was there about 10 years ago and late april early May. It was |
|
| 174:36 | 100 20 degrees out here on the . Alright. And so let me |
|
| 174:41 | show you some of the pictures. right, just give you a feel |
|
| 174:45 | how these things are put together This is the Saka. Okay. |
|
| 174:50 | , there's a major giant oil field occurs right here called do han oil |
|
| 174:54 | that we're going to talk about later afternoon And there's do an oil field |
|
| 175:00 | discovered back in the 40s. It's big anti client structure. This is |
|
| 175:04 | they found all the giant oil fields the Middle East, right surface expression |
|
| 175:08 | the anti client. I mean, didn't take a lot of rocket science |
|
| 175:13 | find these giant fields. Okay. but that's that's do han field in |
|
| 175:19 | um the peninsula and this is basically of the saga next to it. |
|
| 175:25 | right. So, you can see the large scale political mud cracking like |
|
| 175:30 | showed you for abu Dhabi you precipitate of the gypsum of these mud cracks |
|
| 175:35 | they are zones of permeability. But different here is you get not only |
|
| 175:41 | mud crack, the big plugging all cracking, but you get segmentation, |
|
| 175:46 | precipitate a reaganite and I met calcite gypsum in the sediment. And then |
|
| 175:52 | happens to the cement of crusts? start buckling. Okay, see the |
|
| 175:56 | effect here. These are called teepee . Okay. And these are due |
|
| 176:03 | to the force of crystallization. there's no vegetation, there's no roots |
|
| 176:08 | anything to push them up. There's vegetation. So, I want you |
|
| 176:12 | appreciate that because in the arid ancient flat complex, you can actually get |
|
| 176:17 | buckling effect. You can see it , You can see it even in |
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| 176:20 | three inch quarter. Okay, so what that's related to. All |
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| 176:26 | these are teepee structures mostly driven by precipitation. And then we dug a |
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| 176:33 | of trenches back here on these and one trench showed. And hydrate. |
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| 176:40 | this is what the anhydride look And it's not even the same style |
|
| 176:44 | an hydrate that I showed you in Dhabi. Right? It's a layer |
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| 176:47 | anhydride, but it's not that distinct fabric like I showed you before. |
|
| 176:53 | . Most of the evaporates on the uh peninsula are again big discord crystals |
|
| 177:03 | gypsum I mean look at the size of these crystals are this big. |
|
| 177:08 | , and you can see my colleague is holding one up, you can |
|
| 177:12 | translucent through the crystal. You can him just scattered on the surface by |
|
| 177:18 | . By wind deflation. You actually out some of these big gypsum |
|
| 177:23 | Okay, so appreciate that relationship And then when you get there, |
|
| 177:29 | you get natural cuts or artificial cuts the water comes back in, you |
|
| 177:33 | see that this stuff is all primed precipitation. You get probably in part |
|
| 177:39 | driven precipitation of these gypsum crust like see here. Alright, sometimes it's |
|
| 177:45 | bacteria sometimes it's the cyanobacteria. but I appreciate all of these chips |
|
| 177:52 | this being precipitated in this setup. , we see things like this in |
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| 177:57 | rock record. Where for this title , It's just dominated by gypsum. |
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| 178:01 | , so it's probably this kind of here where you had exchange of water |
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| 178:05 | into the inner part of this huge flat complex and you precipitate out this |
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| 178:11 | fabric. Okay. Alright. Any or comments about the carbonate ramp |
|
| 178:21 | So, we have the two end models, right? Steep margin platform |
|
| 178:25 | we talked about for the Bahamas ramp . Right? You can have anything |
|
| 178:33 | between. Right. We have to two end member models for a starting |
|
| 178:38 | for discussion. All right. And change the slope angle a little |
|
| 178:45 | Right? That could change the You're gonna see later today that ramps |
|
| 178:51 | do what they can evolve to a margin platform. It's harder to go |
|
| 178:56 | this back to this unless you fill hole in with plastics. Okay, |
|
| 179:03 | again, remember the limitation, everything showed you now in the modern is |
|
| 179:07 | time factor, right? We're only about 5 to 7000 years and |
|
| 179:13 | most of what I showed is probably than 3, 33,000 years of |
|
| 179:18 | So that's the limitation. Right? we need to make the time |
|
| 179:23 | So, we're gonna do this after when we get into sequences and cyclist |
|
| 179:27 | . But let's take a five minute . And we'll come back and start |
|
| 179:30 | on the evaporate story just to complete story. I've already introduced you to |
|
| 179:35 | evaporate minerals. But let me fully that relationship in five minutes. |
|
| 179:40 | so let's take a break. so the next the next formal lecture |
|
| 179:48 | a lecture 11 on evaporates, models formation and relationship with carbonates. |
|
| 179:55 | And so you have the lecture slides you have a little short. Right |
|
| 179:59 | again there there are a lot of that have been published on evaporate |
|
| 180:03 | And they're in a relationship with with . So there's no way I'm going |
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| 180:08 | replicate things that have been published in format. Um But let me just |
|
| 180:14 | again the requirements for making evaporate And then we'll talk about some of |
|
| 180:19 | models that people have come up with explain the different styles of evaporate |
|
| 180:25 | And then we'll finish up by talking the interplay between carbonates and plastics. |
|
| 180:29 | then that will be built on obviously weekend when we talk about play |
|
| 180:35 | Okay, Because while strictly speaking, or not carbonate minerals there, as |
|
| 180:40 | already seen, there are often closely to a lot of these carbonate |
|
| 180:46 | Okay, so the first thing to , I mean, the very first |
|
| 180:52 | I had last friday, I showed the composition of sea water. |
|
| 180:58 | And I showed you the different cat that are associated with sea water. |
|
| 181:03 | you remember things like magnesium are pretty sodium and and chloride. Pretty |
|
| 181:10 | Obviously, calcium and magnesium. you know, I guess the first |
|
| 181:16 | to to address is take a bucket seawater and evaporated. Right, what |
|
| 181:23 | the order of mineral precipitation. And says, what's the first mineral that |
|
| 181:28 | out? Everybody says, oh, . Right. No, it's not |
|
| 181:32 | . The first mineral that comes out calcium carbonate actually precipitate out raga night |
|
| 181:38 | Hyman calcite. Okay, then the mineral that comes out is calcium |
|
| 181:45 | So that's gypsum if it's wetted, , which it would be. And |
|
| 181:50 | what's the next mineral? Hey right, sodium chloride and then magnesium |
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| 181:58 | and potassium chloride, which is called . And then all these weird so |
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| 182:03 | veteran salts and Bishop fight is one them. I don't even know what |
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| 182:08 | composition that is, but it's got these different cat eyes mixed in with |
|
| 182:13 | chloride. Okay, so what this shows you is the theoretical profile if |
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| 182:21 | took a standing body of seawater and it versus the average what we see |
|
| 182:29 | the rock record. Okay, not right. So theoretically you see on |
|
| 182:43 | left right, the average what you get from seawater directly would be a |
|
| 182:48 | proportion of hey, light and not much as the bitter insults. Not |
|
| 182:53 | much as the not as much of intermixed carbonate and gypsum. Right. |
|
| 182:58 | then contrast that with the average you in the rock record, you see |
|
| 183:03 | greater percentage of intermixed calcite or calcium and either, hey, I'm |
|
| 183:10 | either gypsum or and hydrate and not great a thickness of daylight and certainly |
|
| 183:18 | a great as thickness of those weird insults. Okay, so what does |
|
| 183:23 | mean? It means that, you , first thing first thing to appreciate |
|
| 183:29 | to account for some of the thicknesses going to show you and the rock |
|
| 183:34 | , right? The, you can't this from one standing poor volume of |
|
| 183:41 | . So what do you need, need recharge. Just like we talked |
|
| 183:44 | for diarrhea genesis, right? You've to recharge for marine sanitation. You |
|
| 183:49 | recharge for freshwater, gotta recharge to it evaporate, make dolomite and evaporative |
|
| 183:56 | . You've got to do the same here with evaporates, you've gotta have |
|
| 184:00 | . Okay, so all the models going to come up with some mechanism |
|
| 184:03 | recharge. Okay, But then what every time you recharge, what are |
|
| 184:08 | gonna do? You're gonna dissolve some those more soluble minerals like hey |
|
| 184:14 | like the bitter insults. Okay, that's the excuse things toward more of |
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| 184:19 | accumulation of intermixed calcium carbonate and minerals gypsum. Okay, so just keep |
|
| 184:27 | in mind. Alright, so in literature there are a bunch of different |
|
| 184:32 | for explaining different types of evaporate Alright, and the first thing people |
|
| 184:40 | is they talk about a basin of of evaporate deposition. Alright, so |
|
| 184:47 | talking about the transition from land to deeper subtitle environment. Right? That's |
|
| 184:54 | they mean by basin, that's how using the term base in here. |
|
| 184:57 | then they talk about basin margin and basin center. Okay. And so |
|
| 185:04 | people have related evaporate deposition of the called basin center and they've related evaporate |
|
| 185:11 | . The so called basin margin which include some of these shallow restricted |
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| 185:16 | would include the Saka along the shore , would include would include what we |
|
| 185:21 | pliers, which are not marine. there, continental evaporate deposits. |
|
| 185:28 | so let me put this in Alright, and I'll do that in |
|
| 185:34 | second with another diagram. But one the limitations today is that we don't |
|
| 185:40 | the right kinds of settings for major deposition like we had back in the |
|
| 185:45 | record, it's very common to see evaporate deposits in the basin or in |
|
| 185:52 | settings back in the rock record. we didn't have those kinds of |
|
| 185:56 | Today, most of our evaporates are with things like coastal Selena's or tidal |
|
| 186:03 | , but we don't have any deep settings. Today, we can accumulate |
|
| 186:07 | minerals. Right? So these are modern day settings where you get |
|
| 186:11 | but none of them are associated with subtitle environments where you could get evaporate |
|
| 186:16 | . Alright. And but people have today in the modern is we have |
|
| 186:27 | continental evaporates but by definition or not . This is where you get the |
|
| 186:32 | . I'll show you what this looks in a minute where you get some |
|
| 186:36 | these different kinds of crystals associated with . And then the coastal Sakas, |
|
| 186:40 | already talked a little bit about this ? For abu Dhabi right? And |
|
| 186:44 | saw you got natural and hydrate and crystals of gypsum and stuff like |
|
| 186:50 | And we haven't talked about the sub asse of apa rights yet but people |
|
| 186:56 | you can get different kinds of crystal and minerals associated with that. |
|
| 187:02 | And the problem is when they document , they try to take the crystal |
|
| 187:06 | back to the rock record and use crystal shaped to say oh that's a |
|
| 187:11 | go or oh that's a client, a sub Aquarius evaporate deposit. |
|
| 187:17 | And that's very, very dangerous because minerals are highly unstable. Gypsum very |
|
| 187:24 | and hydrates, unstable and if you them or you uplift them they can |
|
| 187:32 | crystallize and when they re crystallize they change their crystal morphology. So that's |
|
| 187:38 | danger of trying to use evaporate crystal to interpret de positional setting. |
|
| 187:44 | so you see one fabric here, here, under the sub with these |
|
| 187:50 | shape chris sorry, with these palm crystals. See what I'm talking about |
|
| 187:57 | here, right there. I'm shape that stick up like this when you |
|
| 188:05 | this in the rock rock record, would say probably what that indicates is |
|
| 188:13 | that grew up, right? And only way you could do that would |
|
| 188:16 | if you're underwater. Okay, But doesn't prove water depth, right? |
|
| 188:22 | could be a foot of water. could be, you know, tens |
|
| 188:25 | feet of water and more. All . So, about the only reliable |
|
| 188:29 | that is shown on this diagram is is called a palm eight structure. |
|
| 188:35 | the shape of the crystals like the of your palm. And when people |
|
| 188:39 | this in core subsurface data, they'll that to be sub acquiesce evaporate |
|
| 188:44 | Okay. There's nothing like this has found in a coastal Sokka or a |
|
| 188:50 | apply sunny. Okay. But the of this stuff I would be very |
|
| 188:56 | trying to use in the rock Okay, Because of the potential for |
|
| 189:00 | minerals to re precipitate. Okay, let me let me come back to |
|
| 189:08 | let me put a context to what just said. All right. |
|
| 189:14 | this whole model here incorporates what people call a basin. Right? We |
|
| 189:19 | from land out into a true open setting. Right? That's how some |
|
| 189:24 | use the term base. Now, that basin, you see variations and |
|
| 189:29 | , right? You have the basin , open ocean, right to the |
|
| 189:36 | ? And then this is what we a shallow restricted or interpret tonic |
|
| 189:41 | Okay. And then along the shore , I showed you where we could |
|
| 189:45 | beach ridges or topography and create a lagoon behind it. Right. We |
|
| 189:50 | that in abu Dhabi saw that on right. For the for the sands |
|
| 189:55 | created and created restricted to that predict back here and then the shore line |
|
| 190:00 | could have Sokka and then a true marine setting. The continental applies back |
|
| 190:05 | . Okay, so this is these the settings where potentially get evaporate minerals |
|
| 190:11 | if you have a recharge mechanism and have a dry enough climate for precipitating |
|
| 190:17 | minerals. Okay, so we're gonna with apply a and worked our way |
|
| 190:22 | way to hear. Okay, you get evaporates and true open ocean |
|
| 190:28 | right? They're too deep there to marine, right? Not restricted. |
|
| 190:35 | you only get them in a shallow basin like this. If you have |
|
| 190:39 | sill here to inhibit periodic recharge of basin. Okay, so this is |
|
| 190:45 | special setting where you have this unique base. So you all know the |
|
| 190:50 | of Gibraltar in the mediterranean sea. an example of a silver basin. |
|
| 190:55 | , straits of Gibraltar pop up close sea level and periodically through the tertiary |
|
| 190:59 | restricted inflow of marine water into the sea. And what do you get |
|
| 191:06 | the tertiary? You get 5000 ft what people call this? Indian |
|
| 191:11 | Mississippian was a time period in in the tertiary. Alright, so |
|
| 191:16 | gotta have recharge and but you gotta it. Alright. Alright, so |
|
| 191:22 | just go through these models and I'll show you what I'm talking about. |
|
| 191:25 | the pliers pliers are the apparat deposits form in inter mountain basins. |
|
| 191:33 | So, you know the basin and setting that occurs today in the western |
|
| 191:38 | . You go to New Mexico right? You got a mountain range |
|
| 191:42 | , Got a mountain range here, got a depression in between. |
|
| 191:46 | And if you're exposed rocks in that belt have evaporate minerals in them, |
|
| 191:54 | can be subjected to uh weathering or by groundwater. Okay, And you |
|
| 192:03 | the you remove the let me change story, you remove the, the |
|
| 192:14 | , right? You dissolve the minerals around hydrate in the mountains and then |
|
| 192:19 | groundwater flow. Where does it It goes down to the low area |
|
| 192:24 | in what's called apply a lake right the depression. So you make these |
|
| 192:29 | ply of lakes every flooding event. then what happens with evaporation, you |
|
| 192:34 | to precipitate out your evaporate minerals. . And what's the first thing that |
|
| 192:39 | out again? Calcium carbonate and then them. And then hey, like |
|
| 192:46 | . And so the famous example of , maybe some of you been out |
|
| 192:50 | is white sands in New Mexico, ? It's a national monument, soon |
|
| 192:56 | be a national park. I think going to turn into a national park |
|
| 193:01 | this is took this photo on the side of the basin, Right? |
|
| 193:06 | is the sacramento mountains, that's the of Alamogordo is down here somewhere. |
|
| 193:13 | , And then in the distance you the white sands, and then on |
|
| 193:16 | other side is the other side of basin, right? The the or |
|
| 193:21 | mountains. Right? And it's on sides where you have permanent evaporates outcropping |
|
| 193:29 | are being dissolved out by groundwater. . And so that that stuff flows |
|
| 193:34 | to the plight of lake. The plight of lake is called Lake |
|
| 193:39 | . All right, Lake Lake. me skip ahead here. Lake |
|
| 193:45 | Alright, And here's one of my and colleagues Eva who's in the dry |
|
| 193:53 | of Lake lucero. Right? And can see the crystals that precipitate |
|
| 193:58 | and you see the pomade shape that was talking about. You see us |
|
| 194:01 | growth like growth position, Right? so this is inferred to precipitated from |
|
| 194:06 | standing body of water, and then dries out, and then what |
|
| 194:11 | It gets starts to get deflated and by wind, and then all of |
|
| 194:16 | stuff then gets turns into little fine sand which makes up the famous gypsum |
|
| 194:22 | at white sands. Okay, And if you've been out there, |
|
| 194:27 | mean you wouldn't forget this stuff. ? Some of these dunes are up |
|
| 194:32 | 30, 40 ft high. All , so there's a source the |
|
| 194:38 | the dry which goes periodically dry. then the wind blows the stuff up |
|
| 194:42 | the up to the to the Okay? And you get the gypsum |
|
| 194:47 | forming here. Alright, so ideally is the pattern that you would create |
|
| 194:53 | right? Uh If you had the and you dry it out right, |
|
| 194:59 | precipitate the material out of that You produces bull's eye pattern. The |
|
| 195:07 | part would be dominated by carbonates, to precipitate first and then gypsum and |
|
| 195:12 | the center would be hey light. , but you never achieve that here |
|
| 195:17 | lake lucero. It just goes to . The any hey light that precipitated |
|
| 195:23 | is ephemeral. It's dissolved out during next flooding event. And so you |
|
| 195:29 | really generate the gypsum that makes up dunes. Okay, so that |
|
| 195:34 | I mean that's not carbonate. I it's not related to marine carbonates but |
|
| 195:41 | it's a deposition model for making Okay. And then coming closer to |
|
| 195:47 | so called basin margin, right closer the exposed landmass on the edge of |
|
| 195:52 | basin. This is where you get the Sakas developed like we talked about |
|
| 195:57 | for the abu Dhabi or you get coastal Selena's that I talked about last |
|
| 196:04 | . Alright, so we've already I'm going to beat a horse dead |
|
| 196:09 | As you can see the we've already about this setting, right? The |
|
| 196:14 | is fed by the lagoon. waters that are delivered by the shamal |
|
| 196:20 | or the mateo tsunamis. We talked this. We talked about this. |
|
| 196:27 | then remember the byproduct of this evaporate is first precipitation of gypsum in the |
|
| 196:33 | sediments. These are display sieve crystals gypsum. Alright. And then we |
|
| 196:40 | about what happens sometimes in this Aka We still get the gypsum. |
|
| 196:45 | still get the proto dolomite. But we get the anhydride. Like we |
|
| 196:49 | about through both the abu Dhabi and . Alright, so that's the Saka |
|
| 196:56 | . Alright. And there are the that I just showed you. All |
|
| 197:02 | ? So, I don't need to the horse dead again. All |
|
| 197:06 | And then the next model would be variation on this model would be the |
|
| 197:11 | Selena model. Well, this is model that I showed you for making |
|
| 197:16 | last weekend. Remember this is keiko's . We're really close to the basin |
|
| 197:22 | . The platform edges right here. no scale here, but that's about |
|
| 197:28 | 100 m okay offshore. I if you had a really good |
|
| 197:32 | you could throw a baseball into the from that shore line. Okay, |
|
| 197:39 | how does the coastal Selena work? works by the interplay of the |
|
| 197:44 | Older topography is the high pleistocene 70 ft above sea level. The |
|
| 197:52 | , high topography is the Holocene Beech here, about 25 ft above sea |
|
| 197:57 | . All right. In that natural is the sink for collecting marine |
|
| 198:04 | Either during hurricanes where you get over or even just in a winter when |
|
| 198:12 | When 15 or 20 ft swells hit shore line. It will push marine |
|
| 198:17 | through that porous and permeable beach ridge it will fill that Selena. And |
|
| 198:23 | nature takes over. You get natural . Right? I show you showed |
|
| 198:27 | these slides last time where you evaporate to hey light on the surface. |
|
| 198:34 | what do you precipitate in the You precipitate gypsum, right, Little |
|
| 198:39 | and gypsum and some of the maths slugs of mush of little gypsum crystals |
|
| 198:47 | precipitate below that surface. Hey, never gets preserved. It always dissolves |
|
| 198:53 | every time you re flood. But we talked about the implications of |
|
| 198:58 | , right? That those magnesium rich then could sink down and Dolma ties |
|
| 199:04 | of that underlying carbonate. Okay, this is basically another model variation on |
|
| 199:08 | theme for creating conditions for making evaporates then can interact with some of the |
|
| 199:16 | fabric. Okay, so that's the Carolina or what people would call shallow |
|
| 199:24 | . Uh That occurs along the shore . Alright, and then the last |
|
| 199:29 | would be the shallow restricted basin model you have to have a sill |
|
| 199:35 | You have to be linked to the ocean because you need periodic recharge to |
|
| 199:39 | for these evaporate minerals. Alright. what's evolved in the literature are three |
|
| 199:46 | called basin center evaporate models number none these basins are incredibly deep. But |
|
| 199:53 | all silver and they're all linked to deeper open ocean. Alright, so |
|
| 199:58 | first model is the so called deep deep basin model where the hole was |
|
| 200:04 | deep here and you restricted inflow of water into this basin. And where |
|
| 200:11 | you make the evaporates? You don't it in deep water, You make |
|
| 200:14 | up here in shallow water or along margin of the basin and then you |
|
| 200:19 | settle that stuff out or displace it gravity flow and accumulated down in the |
|
| 200:24 | water. Okay, the other end model, this is a so called |
|
| 200:34 | water shallow basin model or the basin got very deep. It was restricted |
|
| 200:39 | a sill again to let water in out. But basically the evaporates form |
|
| 200:46 | shallow water right on the sea Okay. And they just accumulate through |
|
| 200:51 | with repetitive recharge. Alright, so the so called shallow water shallow basin |
|
| 200:57 | very deep. And then there's this model that was published by a guy |
|
| 201:03 | ken Sue who was work for shells lab. Alright. And uh He |
|
| 201:12 | was trying to explain the Mediterranean evaporates I just talked about, right, |
|
| 201:17 | 5000 ft thick, tertiary aged evaporates the Mediterranean basin. And his concept |
|
| 201:24 | that we had a sill. and periodically seawater would cascade over that |
|
| 201:31 | and add water to the basin. the they call it a shallow water |
|
| 201:37 | basin model. A big hole but never very deep in that |
|
| 201:42 | Okay, It only got flooded periodically by influx of submarine water. And |
|
| 201:49 | with time with subsidence, this is you build those 5000 ft of the |
|
| 201:54 | and evaporates up with periodic recharge into deep hole, but never into a |
|
| 201:59 | water setting. You'll understand what I'm . This is his idea. |
|
| 202:04 | so not everybody agrees with this but but this is the, this |
|
| 202:09 | that hybrid model between the other two . Okay, so in this |
|
| 202:15 | right for basin center to evaporate none of these are deep water |
|
| 202:20 | but they're linked to an open So if you look at this and |
|
| 202:25 | section, it sort of looks like eyeball and cross sectional view. If |
|
| 202:29 | look at the hey, light is lens to the eye. Right? |
|
| 202:33 | the water is coming from right to closer to the source. You get |
|
| 202:37 | precipitation of carbonate minerals and then a bit further back, you would get |
|
| 202:42 | gypsum dominating and then the more distal part would be dominated by hey, |
|
| 202:47 | , okay, that would be the ideal distribution of the, of the |
|
| 202:52 | minerals. But you don't always see again because when you recharge, you |
|
| 202:57 | dissolve some of that. Hey, and not preserved. Okay, |
|
| 203:04 | everybody clear about the models. so famous, ancient example of this |
|
| 203:09 | be what we have in the Permian complex in west texas and new |
|
| 203:14 | We're going to talk a lot about next weekend. From a plate type |
|
| 203:19 | , you've heard of the Permian right? It's a now it's getting |
|
| 203:24 | the notoriety is coming from the shale , right. All the unconventional plays |
|
| 203:29 | west texas and Mexico, but a of conventional carbonate play production from west |
|
| 203:37 | . Going back to the forties and and you can see the topography |
|
| 203:42 | We have uh, we have these basins, the Delaware basin and midland |
|
| 203:48 | . These are classical interpret tonic basins were sealed to the south. |
|
| 203:54 | And probably linked to more open ocean the south. All right. And |
|
| 203:58 | have carbonate deposition up on the shallow carbonate platforms, you have classic fill |
|
| 204:03 | little bit of deep water carbonate fill then look what happens at the end |
|
| 204:08 | of uh of Permian time in this of the world. We fill these |
|
| 204:13 | in with evaporates. So, these basin centered or so called shallow |
|
| 204:19 | You're basing all evaporate deposits. so again, I don't know if |
|
| 204:24 | of you've been out here to this of the world, You ever been |
|
| 204:27 | to Carlsbad that area. So, you drive again from El paso to |
|
| 204:33 | to go to Carlsbad caverns for you would be on this highway and |
|
| 204:37 | you look to the left, you see this outcrop. Okay, this |
|
| 204:42 | the Permian reef complex. You see thing here looks like an elephant growing |
|
| 204:47 | into the side of the mountain, the Permian reef complex. Okay. |
|
| 204:52 | these are some of the big canyons cut through that reef complex. This |
|
| 204:57 | the Delaware basin. It's been it filled in with the vap. |
|
| 205:03 | Okay. Almost, almost all the have been removed by erosion over the |
|
| 205:09 | . Okay, But appreciate that at time. Yeah, hundreds of feet |
|
| 205:16 | evaporates filling the space. In fact lapped up on top of the Permian |
|
| 205:19 | complex. Alright, that's the so castile evaporate. Okay, and the |
|
| 205:25 | looks like this. There's still some along the highway there where you can |
|
| 205:29 | what Castile looks like. This. that barbed evaporated deposit where you go |
|
| 205:34 | carbonate to gypsum, carbonate to Okay, in the subsurface of the |
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| 205:40 | hydrate to gypsum. And people think these are like these are barb like |
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| 205:48 | that represent periodic flooding events, When you flood and then evaporate, |
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| 205:53 | get the darker carbonate first and then precipitate out the gypsum and then you |
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| 205:58 | flood, You do it over and again. Okay. And some people |
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| 206:02 | there's a mobile couple of mobile geologists must have been bored to death because |
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| 206:06 | think they can correlate these things all the Delaware bass, right? They |
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| 206:11 | their time equivalent over some huge Who's going to challenge that, |
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| 206:16 | Unless you want to spend weeks looking core and trying to count layers and |
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| 206:21 | from core to core to core. they claim they could do that. |
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| 206:24 | right, Alright. So that's that an example of a basin all |
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| 206:29 | Right? Never, Never really Okay. Not open ocean restricted by |
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| 206:36 | cil. You've got to have that you've got to have periodic recharge, |
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| 206:40 | you gotta have a dry climate to this precipitation. Okay, now, |
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| 206:46 | the problem. I said, you , you go back to the rock |
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| 206:49 | and you see fabrics like this in rock record. This is And hydrate |
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| 206:55 | , disturbing mosaic, bedded mosaic, these different terms to describe this |
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| 207:01 | You have to be really careful here interpret environments of deposition just based on |
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| 207:05 | fabrics, because you can create this by re crystallization. So, |
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| 207:11 | what I'm saying is some of this could be associated with a basin centered |
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| 207:16 | some of this fabric to be associated a tidal flat, narrow tidal |
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| 207:21 | Okay, by itself, that doesn't anything. So, you have to |
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| 207:25 | into context and look at the other associated with it. Okay. And |
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| 207:30 | reason for that is that when you gypsum And forming at the Earth's surface |
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| 207:37 | when you buried about 2000 ft, water that gypsum, what happens? |
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| 207:42 | converts to an hydrate and when it it can re crystallize. So it |
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| 207:47 | go from a discordant crystal to a regular crystal. Okay. And then |
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| 207:53 | you bring it back up right, uplift and you expose it to water |
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| 207:57 | , it's going to convert back to , then it can re crystallize another |
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| 208:01 | form. That's the problem with evaporate . Okay, if they don't dissolve |
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| 208:06 | which they can do right, they dissolve out, then they're likely to |
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| 208:10 | crystallize and change their crystal morphology. that's why you have to be really |
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| 208:15 | about just using crystal morphology. So the core from the devonian in western |
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| 208:22 | . You know I worked this stuff lot and when I first started working |
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| 208:26 | stuff, everybody told me these natural hide rights are what Sokka, |
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| 208:32 | It looks just like the abu Dhabi stuff. And then when I started |
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| 208:37 | at the rock around it and above and below it. Wait a minute |
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| 208:43 | open remain. This is not This is not a tidal flat. |
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| 208:49 | fact this is not even early precipitated hydrate. This is late stage replace |
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| 208:56 | and hydrate. So here's the other and hydrated formerly in the sediment while |
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| 209:02 | unconsolidated and grow in displays but it can come in and replace a limestone |
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| 209:08 | Dulles stone at depth. Okay. we know this because you can look |
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| 209:14 | this stuff with the white paper technique the fluorescence technique and see the relic |
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| 209:19 | structure. Okay, so be really about just using these fabrics by themselves |
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| 209:26 | interpret de positional setting. Alright. let's summarize the importance of ap writes |
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| 209:33 | carbonates. Alright. I talked about salt swells that occur in the Arabian |
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| 209:37 | . Today we see this all through time. You create topography on the |
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| 209:42 | floor by salt movement. You can what great local areas for reefs, |
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| 209:49 | reefs or fluid sand bodies. we look at the evaporates more from |
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| 209:54 | standpoint of sealing other poorest faces. ? Either by pro gradation or from |
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| 210:00 | basin. We have brief topography. fill the basin with evaporates, evaporates |
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| 210:06 | the side and then top seal for potential reservoir. Okay. And then |
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| 210:12 | always looked at the evaporates also from sword for being a source of magnesium |
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| 210:17 | making Dillaman ization. And some people that locally some of these evaporated bases |
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| 210:24 | be source rocks because what's the only that can live in evaporating basin |
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| 210:30 | Okay. And so some people think could preserve organic material there. And |
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| 210:36 | think you can. All right, you're not going to do it on |
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| 210:39 | great enough volume where it's a major . Right, Okay. So that's |
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| 210:44 | limitation. Plus, what else do have to do? You have to |
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| 210:48 | out of the zappa? Right. . Which we just said is a |
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| 210:52 | ceiling faces. So how are you to get it out of there to |
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| 210:56 | somewhere else. Okay, that's the . All right, so a couple |
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| 211:01 | here. Right. Example from the , we'll talk about next weekend, |
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| 211:07 | swell build up salt high on the floor that can localize a reef or |
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| 211:12 | can localize wet sand bodies. Like see here in this example from east |
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| 211:17 | , in the Jurassic, every one these yellow blobs you see here is |
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| 211:21 | salt related structure that created topography for deposition. Then sometimes, as I |
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| 211:28 | , salt will withdraw. Right? you create a sink sag. |
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| 211:34 | some of these white sands were found by looking for the highs, but |
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| 211:37 | looking for the lows because of that withdrawal. Okay, So sometimes this |
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| 211:42 | associated with the lows. And then an example from the Mississippi in where |
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| 211:48 | reservoir are these elliptic grain stones that grade because this is a ramp |
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| 211:54 | And what's pro grading on top of grain stone? Are the critic, |
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| 211:59 | lagoon or sapa deposits shown by Right. And they provide the top |
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| 212:06 | for that program. Additional uh, grain stone. Alright. And then |
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| 212:12 | example of this would be a type reef that we're gonna call pinnacle reefs |
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| 212:17 | weekend where pinnacle reefs form out into basin. They started a little bit |
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| 212:22 | water. They build up vertically through . And sometimes they can they can |
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| 212:27 | encased in basin basin. It That's the A two car a to |
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| 212:34 | that you see here that provides the and top seals for the reservoir. |
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| 212:39 | also think it provides a source for magnesium to convert these reefs to dolomite |
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| 212:44 | all the reservoirs have to be Ized to be productive. Alright. |
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| 212:51 | then one last point here about and and gypsum, they not only could |
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| 212:57 | early display sieve and then replace it late or early replace the minerals. |
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| 213:07 | can be portfolio in cement and they kill porosity by that. Right? |
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| 213:12 | see the end, you see the here filled with an hydrate. You |
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| 213:15 | the financial proxy for this Permian stone filled with and hydrate cement. |
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| 213:21 | ? So this is a real Some basis. Right. These carbonates |
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| 213:26 | great reservoir quality. They lost it during their barrel history because of |
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| 213:35 | Okay. Alright. I went a bit over just to finish this up |
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| 213:40 | lunch. So, you got an for lunch. Right? So let's |
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| 213:44 | 10 after 11. I mean 10 one, sorry, 10 after |
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| 213:49 | We'll start back up. All |
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