| 00:02 | Yeah. Let me Hold on a . So sorry. Mhm. |
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| 01:30 | So that we're going to start with bright zones is one of the three |
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| 01:33 | of colonial organisms and have a relatively skeleton. Uh Some of the bright |
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| 01:39 | and skeletons are so delicate. You you can actually crush their skeleton in |
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| 01:44 | hand. You can never do that coral or a stream atop roid. |
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| 01:49 | You can see that they have different is and we're gonna make a big |
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| 01:52 | about morphology is and relate them to and or water depth at the time |
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| 01:58 | deposition. So, some Brazilians are summer and clusters. Some have a |
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| 02:03 | massive morphology that some people call What's unique about the broad zones is |
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| 02:10 | they're comprised of these very small tubes are generally millimeter across or less. |
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| 02:20 | it's in those tubes that the organism right and extended out and filter |
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| 02:24 | And those tubes are divided by cross . We think the mineralogy was principally |
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| 02:31 | acidic. Some debate about whether it's or low medical side to begin |
|
| 02:35 | Uh These things go all the way to the or division. They still |
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| 02:38 | today. And unfortunately they don't they reflect any unique deposition environment. They |
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| 02:44 | widespread distribution. Okay, so this the cartoon that illustrates the the morphology |
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| 03:00 | the micro structure associated with the different . You can see some have the |
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| 03:05 | like structure. These are called. prize owns. Their branch prize owns |
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| 03:09 | encrusted brides owns. It turns out the encrusted morphology is usually the highest |
|
| 03:15 | morphology. Right? If you're in high energy windstorm or something like |
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| 03:19 | you wouldn't want to stand up like because you would get knocked over. |
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| 03:23 | ? So you want to you want hunker down and have low relief. |
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| 03:26 | so usually an interesting morphology reflects the energy deposition all setting. And the |
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| 03:33 | bryson micro structure are the two that shown here. You can see the |
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| 03:38 | partitions and the small little tubes. at the scale here for a |
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| 03:43 | These are almost always less than a across. And then when you look |
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| 03:47 | the cross partitions, they have this preserved laminated calcite micro structure. And |
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| 03:53 | that's usually what you see in the record for the bigger pieces of the |
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| 03:57 | pieces. And that's what we used identify. That fragment is a bright |
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| 04:02 | . Um What's unique is the entrusting structure. You see the you see |
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| 04:08 | the organism grows on itself. That's classical and crusty morphology. But the |
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| 04:14 | tech the micro structure here is the or granular, lighter colored micro structure |
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| 04:20 | much different than what you see for branch store fantasy tree types of |
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| 04:26 | So let's take a look at uh modern examples here. So you can |
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| 04:31 | why we call these colonial organisms, ? Brazilian holes on the surface of |
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| 04:35 | structure at the time of deposition, one of those holes that had been |
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| 04:39 | by living filter feeding animal, but delicate skeleton. And then if you |
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| 04:47 | at the branch paraiso and morphology, is probably the most common that you |
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| 04:52 | in the rock record. Uh If look at a longitudinal cross section |
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| 04:57 | the thing to look for to establish as colonial is to see a bunch |
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| 05:01 | holes tied together like this, That establishes the colonial aspect. And |
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| 05:07 | you look at the size of these and you can see my scale bar |
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| 05:10 | . These are well below a millimeter for scale. And then they have |
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| 05:13 | cross partitions with well preserved laminated Yeah. And notice the color to |
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| 05:20 | is unique to these skeletons. So you see the bigger pieces that are |
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| 05:25 | easy to identify than the smaller pieces . Can also be identified based on |
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| 05:30 | color. Okay, now this is longitudinal cross sectional view. If you |
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| 05:35 | to look down the axis of this , you would see something that looks |
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| 05:39 | this. All right, completely different . But you still see all the |
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| 05:43 | together the colonial aspect. And you the and you see the small size |
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| 05:49 | the holes and then these are still cross partitions that exist. Okay, |
|
| 05:54 | those are bright zones. And when talk about carbonate plays In a couple |
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| 05:59 | weekends, you'll see that bright zones capable of making low relief build ups |
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| 06:04 | the scales of tens of m 200 thick. That's low relief compared to |
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| 06:09 | other build ups and 1000 m 1000 thick. But so we'll talk about |
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| 06:16 | from their for their place perspective and some of these uh, what we |
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| 06:21 | a mound place. Okay. Any about the, about the bright |
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| 06:31 | We cannot example, he recalled. we don't in the modern we don't |
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| 06:40 | any any fries owns that create bigger mounds because we're not in the right |
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| 06:45 | of setting. You're going to see most of these mounds occur in relatively |
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| 06:50 | water. And uh well we have deeper water buildups. They're mostly associated |
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| 06:56 | corals and sponges and things like So the ones we see in shallow |
|
| 07:01 | are mostly either the free growing branching or more typically the Crestor is then |
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| 07:08 | on the bigger shell or they in on sea grass or something like |
|
| 07:13 | Okay, so they're not, I say, you know, they're not |
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| 07:17 | that important from a volumetric standpoint in modern today. That's much more |
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| 07:23 | I think in the rock record, in the paley is like strong. |
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| 07:31 | , but I'm just an observation from experience. So, alright, so |
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| 07:38 | would be the second colonial organism. mean most corals, all the corals |
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| 07:43 | familiar with on the famous reefs around world today, our colonial what that |
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| 07:47 | is not only do they grow on structure that cover the surface of the |
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| 07:51 | every hole is occupied by a coral that filter feeds, but they also |
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| 07:57 | a symbiotic relationship with these oh and algae. Uh The algae give them |
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| 08:02 | color, the algae uh help them their structure. The algae actually feed |
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| 08:07 | too. They create sugars and feed coral. So they have a really |
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| 08:11 | symbiotic relationship. But there are some called solitary corals that exist today and |
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| 08:17 | existed back in the rock record. are the deeper water corals that don't |
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| 08:22 | light right? All the shallow colonial need light not for themselves, but |
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| 08:27 | their for the their symbiosis with the . Uh So you know the famous |
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| 08:33 | coral that people like the black coral the red coral. Those occur down |
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| 08:39 | much deeper water today off the edges these platforms. Those are solitary |
|
| 08:43 | Alright, but they're relatively minor compared the shallower colonial corals. Okay, |
|
| 08:50 | what's unique about the corals? Is one of the, one of the |
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| 08:54 | groups of skeletal material we're gonna call marine. Remember my definition of open |
|
| 09:00 | yesterday was normal salinity 35 parts per today. And of dissolved solids. |
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| 09:07 | then good exchanges seawater through that And so finding corals in the rock |
|
| 09:13 | tells you something about the deposition You know, you're not in a |
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| 09:17 | restricted platform interior ramp interior setting. know, in your open ocean setting |
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| 09:23 | doesn't solve the question exactly where And doesn't solve the question about how deep |
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| 09:28 | shallow you might be. But but least it's a clue about your general |
|
| 09:33 | . And uh of course most of corals are attached to the bottom, |
|
| 09:37 | ? Have to be attached to harder . Not all corals do that, |
|
| 09:40 | most of them do. And the today are all of the Claritin ian |
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| 09:46 | of coral. These evolved out of Triassic and they're all a raga |
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| 09:51 | which means their potential for preserving their . Very poor because as we'll talk |
|
| 09:55 | later today or agonizes very susceptible to genesis to dissolution re crystallization. But |
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| 10:03 | the scar tinian corals have this really six full radial symmetry. If you |
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| 10:07 | down, if you look down one the polyps, you can see the |
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| 10:11 | radio symmetry which is unique to the tinian corals. Now, if you |
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| 10:16 | the paleozoic, you deal with these two groups here, the rubio squirrels |
|
| 10:21 | the tabulate corals. And these are siddiq. And so their potential for |
|
| 10:26 | their structure is very good. And can see that the Rubios corals are |
|
| 10:32 | confined arkan. They're both confined to paleozoic right? So they start in |
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| 10:36 | camera and at least some people think start in the camera go up to |
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| 10:40 | traffic up to the lower Triassic, route goes, corals have both horizontal |
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| 10:46 | vertical elements. So if you look their structure, you'll see things going |
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| 10:50 | this. But you'll also see structures like this. And then the size |
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| 10:55 | the hole that correlate is relatively It's usually greater than a millimeter |
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| 11:02 | Should be much larger than what I showed you for the bride zones. |
|
| 11:06 | . And then the tabulates have similar distribution. But when you look at |
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| 11:12 | coral structure, it's mostly horizontal cross . All right. There's some vertical |
|
| 11:18 | not as many as you would see rubio's coral. So here's the cartoon |
|
| 11:23 | illustrates these different micro structures. If will the tabulate corals look like this |
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| 11:30 | they have the mostly horizontal cross And then the openings again are much |
|
| 11:35 | than a millimeter across for scale. then the Rubios corals look like |
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| 11:41 | Right? They have both vertical and across partitions. These are the correlates |
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| 11:46 | again are much bigger than a millimeter . So really you shouldn't confuse these |
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| 11:51 | the dry zones. If you compare sizes. Okay. And then the |
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| 11:55 | training corals. If you look down correlate here, you can see a |
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| 11:59 | sixfold radial symmetry. And when there's a magnetic like they are in the |
|
| 12:05 | the dragon eyes shows this very unique structure. The skeleton shows this uh |
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| 12:10 | fibrous micro structure which is very easy identify even in the tiny pieces of |
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| 12:16 | coral while there's still a magnetic. of course the problem is when you |
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| 12:19 | back to the rock record, what's to happen to reaganite? It's going |
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| 12:22 | dissolve or re crystallized. That's always issue now. Like I talked about |
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| 12:27 | the bright zones. The corals also morphological variations from branched, the horn |
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| 12:35 | to n cresting too thin plate. . And I'll relate these all to |
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| 12:38 | modern brief systems to begin with. the next weekend. And then we'll |
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| 12:44 | on this by taking you back to rock record. And when we go |
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| 12:47 | some of these reef plays in the record, you can see how the |
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| 12:52 | helps us decide where we drilled in that reef complex. Okay. So |
|
| 12:56 | me just hold off on that because cover this in more detail. Uh |
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| 13:04 | . Yeah, she's done. It the surface of the coral structure has |
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| 13:14 | zillion, little holes like the like . Okay. And on the surface |
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| 13:19 | of these holes would have been occupied living filter feeding coral polyp. |
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| 13:26 | And then they grow another level and re colonize that level and that's how |
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| 13:31 | achieve that greater thickness. Alright. they only live in the upper level |
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| 13:35 | any one point in time because they're feeders. And they also have that |
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| 13:39 | relationship with the algae. And so algae need to be right looking up |
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| 13:44 | the light in order to take care their coral buddies. Okay, so |
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| 13:51 | these are the scar tinian corals. is applies to scene carl and you |
|
| 13:57 | see the look. I apologize for well I don't apologize now because I |
|
| 14:02 | a millimeter scale here. But you see the size of these. Uh |
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| 14:07 | coral lights are a millimeter or so for scale, much much larger than |
|
| 14:12 | would expect to see for bright All right, so this is just |
|
| 14:16 | closer view of that fabric and thin . These are the correlates. These |
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| 14:21 | the cross partitions of vertical cross partitions septa. You don't need to remember |
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| 14:26 | of that but but just appreciate that has this unique symmetry when you look |
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| 14:31 | the the coral light structure. All now compare this with the paleozoic |
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| 14:37 | This is a thin section of a piece of rubio's coral. And on |
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| 14:42 | bigger scale this would be classical horn corals. Uh Some of this |
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| 14:47 | I've seen an outcrop, some horn corals are as big as my leg |
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| 14:51 | to give you a feel for the . And and these uh you can |
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| 14:57 | that they're both horizontal and vertical cross . Alright now all these holes are |
|
| 15:02 | in with later cement because of die . But the size of these openings |
|
| 15:07 | are just a millimeter or more So again, you shouldn't confuse this |
|
| 15:12 | the bride zone. And then the corals. This is core, through |
|
| 15:17 | devonian example here, where you look these vertical, they look like soda |
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| 15:21 | with, with horizontal across partitions. are the living institute of tabulate corals |
|
| 15:28 | are pretty common in the lower belly like, okay, so we'll put |
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| 15:32 | this into perspective. Obviously when we about refill systems next weekend. All |
|
| 15:39 | . Any questions about the corals before move on? All right. And |
|
| 15:47 | the third group of potential colonial organisms often are rebuilding our storm atop roids |
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| 15:53 | stream atop roids are limited to certain time periods in terms of abundance. |
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| 15:59 | are very common in the slurring and . And then there's a big mass |
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| 16:03 | at the end of the devonian and seem to disappear, but they couldn't |
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| 16:07 | disappeared because they come back again in Jurassic and they hang around in the |
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| 16:12 | end, the lower cretaceous. And they, for the most part seemed |
|
| 16:18 | disappear again. Although some people think of our modern, what we call |
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| 16:22 | sponges. Modern reef systems are related the stream atop words. So who |
|
| 16:27 | , I mean, this is this paleobiology and this is not my, |
|
| 16:32 | my forte. But um, what's about this term atop rises. The |
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| 16:38 | massive forms show this classical, what refer to as a lamb eater and |
|
| 16:44 | structure. So you can see the sheets of calcium carbonate. And most |
|
| 16:50 | think these are probably cal civic some again about higher Loma calcite and they |
|
| 16:57 | that because again, the structures are well preserved in the rock record. |
|
| 17:02 | those sheets are supported by these vertical , but the vertical pillars are |
|
| 17:10 | All right. And so unlike the and bright zones where you saw the |
|
| 17:14 | was distinctly uh segmented by those cross right here. If you were a |
|
| 17:23 | , you could actually snake your way this structure. All right. So |
|
| 17:26 | not completely sealed off by these vertical . And so people refer that to |
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| 17:32 | as an open gallery structure. And is unique to the storm atop |
|
| 17:36 | Okay. And uh let's just look some examples here. Again, the |
|
| 17:43 | forms always show the classical laminar pillar , but you can see sometimes the |
|
| 17:48 | pillars are discontinuous. The branching forms we'll talk about in a minute usually |
|
| 17:55 | more of this uh, s timo type of ferocity system or across |
|
| 18:00 | not nearly as well defined as in more massive forms. Okay, And |
|
| 18:06 | going to talk about storm atop Rhode complexes as reservoirs toward the end of |
|
| 18:11 | segment. And you're going to see that there are changes associated with the |
|
| 18:17 | atop word morphology. To tie back a position across these reef systems. |
|
| 18:23 | the highest energy is what is called thick tabular and crusting Stroman top Freud |
|
| 18:29 | and Christine is this high energy And then things like thin tabular way |
|
| 18:34 | like or more delicate branching forms are lower energy expressions of stream atop |
|
| 18:41 | Either because of deeper water or because a protected shallow water setting. |
|
| 18:46 | So we'll make sense out of these habits when I take you through some |
|
| 18:49 | these ancient reefs. Yeah, This is what results. It's from |
|
| 18:56 | No. Mr. Model. It a completely different growth form. |
|
| 19:02 | this is your doctor. These are atop a roids. Yes, completely |
|
| 19:08 | group. Right, Okay. But get confused about that all the |
|
| 19:14 | So, it's a All right. a core just to show you what |
|
| 19:20 | fabric looks like. These are the massive storm atop words and it has |
|
| 19:25 | of a laminated appearance. Right? that laminar structure. But the porosity |
|
| 19:29 | so fine scale here. That's the thing that's different about the strums. |
|
| 19:33 | size of the pores are even smaller what I showed you for the bride |
|
| 19:36 | . All right. So if you too thin section, you can see |
|
| 19:39 | laminar pillar structure. See the horizontal here and then you can see the |
|
| 19:44 | supports. But look how discontinuous they , right there. One here. |
|
| 19:50 | here, One here, One here then they're missing. Pick up another |
|
| 19:54 | . You see what I'm saying That's why people call an open |
|
| 19:58 | And um, But look at the of the ferocity here. That's 500 |
|
| 20:04 | . These pores are well less than millimeter crossed for size, which is |
|
| 20:09 | smallest scale porosity compared to the broad or or corals. Okay. Most |
|
| 20:16 | the storm it operates are open There are few that some people think |
|
| 20:19 | live in more restricted settings. So can't use this strom atop Roy is |
|
| 20:25 | as open green indicator. Next It kind of terms. Alright, |
|
| 20:32 | family. Go ahead. So people saying these are still exist. Some |
|
| 20:38 | think that what people call sclerosis sponges the deeper parts of modern reefs. |
|
| 20:43 | think they're related to the storm atop . Yeah. But they're nowhere near |
|
| 20:50 | common as they were back in the , slurring devonian or Jurassic and cretaceous |
|
| 20:56 | terms of reef builders. Okay. next group would be a kind of |
|
| 21:02 | . This is a family of, organisms. And this is the second |
|
| 21:09 | that indicates good open marine conditions. if you encountered the kind of germs |
|
| 21:13 | crying noise in the rock record, , you know, you were in |
|
| 21:16 | setting of normal salinity, good Uh, paleozoic is dominated by the |
|
| 21:24 | oid, you're all probably seen pictures the Quran droids, the stock organisms |
|
| 21:28 | the branches that were cal Correas. , probably filter feeders. And then |
|
| 21:34 | are mobile forms that exist today. through the rock record. Things like |
|
| 21:40 | brittle stars and the urchins, you're familiar with sand dollars on a beach |
|
| 21:45 | things like that. These are all to the the kind of terms. |
|
| 21:50 | . And what's unique about the kind terms is that, you know, |
|
| 21:53 | that the body structure is made up many smaller plates. And then the |
|
| 21:59 | forms also have spines that are used locomotion. But everything's held together with |
|
| 22:05 | tissue, which means that when these die, they just disintegrate right off |
|
| 22:10 | bat. All right. If they get crunched by again, a stingray |
|
| 22:14 | a shark. Okay. Which is happens quite a bit too. |
|
| 22:19 | they're going to break down into smaller . So, this is what we |
|
| 22:23 | in the rock record. The little for locomotion or the plates which can |
|
| 22:28 | a star shape morphology or a wheel morphology or little prismatic morphology. |
|
| 22:36 | and then what else is unique about the kind of turned pieces. Each |
|
| 22:40 | is essentially one solid crystal of calcium , but its micro porous. |
|
| 22:48 | it's highly micro porous. So you can't really see the ferocity, |
|
| 22:52 | it's one crystal of calcium carbonate. , it's very easy to identify this |
|
| 22:57 | thin section is I'll show you in minute. Okay. No. |
|
| 23:15 | because I can't have a hard time you because of the take a solid |
|
| 23:20 | tom. Okay, they don't have they're all have a heart structure, |
|
| 23:28 | ? But they can be broken up your with your hand, right? |
|
| 23:32 | you've ever picked up a sand right? You could you could break |
|
| 23:35 | easily. So it's uh. so here's a couple of modern |
|
| 23:40 | right? This is the, the with the little spines for locomotion. |
|
| 23:44 | is called the sea biscuit that uh on some of the sand body systems |
|
| 23:48 | cyanobacteria and it has little spines for motion. Okay, I skipped over |
|
| 23:55 | couple of other examples in your notebook the interest of time and then the |
|
| 23:59 | Lloyd's right. You're all familiar with Quran avoids usually cry noise don't preserve |
|
| 24:04 | this. This is highly unusual to the stock trying to preserve. This |
|
| 24:08 | fell into an anoxic body of water preserved. But you can see the |
|
| 24:15 | is made up of pieces of calcium . And then the branches are also |
|
| 24:19 | up of pieces of carton, calcium . And so usually what happens to |
|
| 24:23 | noise in any any account of term that upon death you end up uh |
|
| 24:29 | ends up being fragmented. Either disintegrates or it gets crushed by something |
|
| 24:33 | And so we have a number of pieces preserved. Right? And look |
|
| 24:38 | the white color to a lot of grains, right? So the the |
|
| 24:42 | color is a reflection of micro porosity I talked about. Micro porous grains |
|
| 24:46 | you reflect light on micro porous that light comes back at you. |
|
| 24:50 | it always takes on that light ish . Right? And so the light |
|
| 24:55 | is actually reflecting that micro ferocity. uh the other thing that's unique about |
|
| 25:00 | grains again is because they're micro that the tiny little porosity tends to |
|
| 25:08 | a lot of of bits and pieces Mick, right? Or or curtain |
|
| 25:14 | cement. And you see this classical appearance to these grains. So every |
|
| 25:19 | of these grains that has this sort uh tan ish color but with a |
|
| 25:24 | appearance is a piece of a Okay. And so they're actually very |
|
| 25:29 | to recognize in thin section. And you can't do it from this |
|
| 25:33 | then you can go to thin section and take your canadarm fragment and then |
|
| 25:41 | the nickels and then rotate the stage And if you do that, you |
|
| 25:46 | the grand ghosts from light color. you see here two dark color. |
|
| 25:51 | you see here, that's called unit , right? This is what |
|
| 25:55 | The single crystal of calcite does. right, you would have probably learned |
|
| 26:00 | an optical mineralogy as an undergrad, you don't remember everything. And That's |
|
| 26:06 | happens every time you rotate the crystal it goes from light to dark light |
|
| 26:11 | dark light to dark. Okay, that's unique to the accounting terms, |
|
| 26:15 | ? All the grains I've talked all the ones I'll talk about after |
|
| 26:19 | when you look at a fragment of , of a bright zone, you |
|
| 26:22 | at a fragment of demolished. It's up of zillions of little crystals, |
|
| 26:27 | one single crystal like each fragment of accounting term is made of. |
|
| 26:32 | so very easy to recognize in thin . Right? Mhm. And then |
|
| 26:39 | curious worm tubes. There there you know, most of our, |
|
| 26:43 | of the marine worms are like soft worms. A lot of them |
|
| 26:47 | The scale of the earthworms are filling on land. All right. And |
|
| 26:51 | burrow through the settlement. But they're small percentage of these worms have the |
|
| 26:57 | to secrete a cal curious structure that like this. And that's called the |
|
| 27:02 | worm tube. And sometimes these are , like I showed you yesterday growing |
|
| 27:08 | the grass blades, Remember those little features. But sometimes they can colonize |
|
| 27:15 | grow one off of the other to little reef like structures. And we |
|
| 27:19 | some in the modern that are five 6 ft high And maybe 10 or |
|
| 27:23 | ft across. Right? That's about big as they get. So, |
|
| 27:26 | not talking about massive refill structures, they can be colonial. Right? |
|
| 27:32 | you know, their colonial when they this when they grow one on top |
|
| 27:35 | the other. So, we're looking the morphology. We're looking for this |
|
| 27:40 | relationship here. And then when you at the the uh micro structure of |
|
| 27:49 | , of the calculus worm tube. of most of these worm tubes or |
|
| 27:52 | acidic. And so they have very preserved laminated calcite. So it makes |
|
| 27:57 | easy to identify. All right. here's a here's an example of a |
|
| 28:02 | colony of worm tubes. So at one point in time every one of |
|
| 28:06 | holes would have been the but would been occupied by living filter feeding |
|
| 28:11 | Okay. Would have been sticking out and feeding and go back to the |
|
| 28:18 | record in thin section. This is there to mineralogy is the calcification neurology |
|
| 28:25 | the most abundant. All right. you know, they're parasitic because the |
|
| 28:32 | the structure of the worm tube is dominated by this well preserved laminated |
|
| 28:38 | Right? You see how they're growing on top of the other? This |
|
| 28:42 | face. Right? Here is actually worm tubes that are attached one on |
|
| 28:46 | of the other. And then sometimes encounter worm tubes that are re |
|
| 28:50 | Like you see here the re crystallized are referred to have been a magnetic |
|
| 28:56 | , because the dragon eye very difficult preserve in the rock record. |
|
| 29:00 | So, you know there their widespread terms of their distribution. They can |
|
| 29:05 | in deeper water. They can be shallow water. So they have no |
|
| 29:09 | environmental significance. Okay. All And then uh if you remember the |
|
| 29:16 | sheet there was that group at the called played the organisms. Right. |
|
| 29:21 | . That created a play D And what do I mean by |
|
| 29:25 | D basically take a take a thing lay's potato chips, right? A |
|
| 29:30 | and pregnant it and make a cross view. Right? You see this |
|
| 29:35 | potato chip like fabric. That's what mean by type lady. And they're |
|
| 29:40 | bunch of groups that fall into the mollison bracket pods of fileted |
|
| 29:45 | And so we have to talk about you differentiate those from each other. |
|
| 29:50 | ? But um start with the bracket . Again, these are Valved |
|
| 29:55 | right? two valves. The organism like an oyster of the organism lives |
|
| 30:00 | filter feeder. Right? So that have opened up to filter feed. |
|
| 30:05 | what's unique about the bracket pods is valve is bigger than the other. |
|
| 30:09 | there's no symmetry between the valves because that difference in size. All |
|
| 30:14 | And then the other thing that's unique the bracket pods is that their shells |
|
| 30:18 | relatively large and robust. Okay. these things had growth lines and growth |
|
| 30:26 | . And they actually some of them spines not for locomotion, but spines |
|
| 30:32 | stick them up above a muddy Okay, So like little still houses |
|
| 30:37 | a marine environment. And then the the classical micro structure. Is that |
|
| 30:47 | layer cal citic component to their All right. I'll show you that |
|
| 30:52 | a minute. All right. this is the third group of what |
|
| 30:55 | call open marine bottom dwellers. So if you encounter braque ipods in |
|
| 31:00 | rock record, you know you're in open marine setting. Now these are |
|
| 31:03 | abundant of paleozoic essentially. Once we into the lower Mesozoic, it seems |
|
| 31:10 | the bracket pots just really dramatically drop in terms of abundance. They're replaced |
|
| 31:15 | the Malia's. Okay. And like and things like that. But there |
|
| 31:20 | a few species of bracket pods that exist today, but not very |
|
| 31:24 | Alright, so here's uh the It's called unilateral symmetry because the symmetry |
|
| 31:30 | not between the shells. The symmetry down the middle of the shell. |
|
| 31:36 | , so that's where the symmetry And then you can see the growth |
|
| 31:40 | here and uh to see some growth here in another example in a |
|
| 31:46 | All right. And then, what's classical micro structure? The calcium |
|
| 31:51 | And by the way, this is very stable low mag calcite shells. |
|
| 31:55 | this is very difficult to dissolve or crystallize in the rock record. The |
|
| 32:00 | micro structure is two layers. A inner layer of preserved laminated calcite and |
|
| 32:08 | a thinner outer layer of prismatic health . Okay. And usually what happens |
|
| 32:13 | that thinner layer breaks off and is preserved in the rock record. All |
|
| 32:17 | see is that thicker laminated layer. . Now the two of the things |
|
| 32:22 | are found in some of the bracket . You see these holes in blue |
|
| 32:26 | . Sometimes they're confined to the inner . That's the name People have come |
|
| 32:30 | with you don't need to remember And sometimes they cut across both |
|
| 32:34 | That's the name people have come up . So punk tater pseudo punk |
|
| 32:39 | I'm certainly not going to test you that and nobody knows for sure what |
|
| 32:46 | these are. But some people, think most people think they probably play |
|
| 32:49 | role in the respiration of the right? To allow it to exchange |
|
| 32:54 | the water. But you don't find in every every bracket pie. But |
|
| 33:00 | you do. All right. And here's a couple examples here. This |
|
| 33:04 | example is lifted from al crop shows the spines that used to support themselves |
|
| 33:09 | a muddy substrate. You can see growth ridges and growth lines. |
|
| 33:14 | And then if you look at an thin section, this is a thin |
|
| 33:17 | through one of the spines which shows classical micro structure. There's a thicker |
|
| 33:24 | layer of well preserved laminated calcite. then a thinner layer outer layer of |
|
| 33:31 | calcite. Okay, and so that's classic. If you if you can |
|
| 33:36 | that. Okay. As I usually the prismatic stuff breaks off and |
|
| 33:41 | just left with a thicker laminated Okay, now that's the spine but |
|
| 33:46 | in the rock record, what we are the valves. So what are |
|
| 33:49 | looking for in in thin section or . This is what I mean by |
|
| 33:54 | plate morphology. Right. This is of like a potato chip and cross |
|
| 33:58 | view and you can see one of growth ridges sticking up here. And |
|
| 34:02 | you see well preserved laminated calcite. , so and robust shells usually. |
|
| 34:08 | so that's the that's the criterion criteria we use for identifying something is a |
|
| 34:15 | pot. And then if we see played a morphology. But we see |
|
| 34:19 | the in this case the punkt eight where cuts all the way through. |
|
| 34:23 | you still have a laminated fabric That is definitely a piece of bracket |
|
| 34:29 | . All right. And then you see associated with crime noise here, |
|
| 34:33 | the dusty color. Uh And then is actually some little bright bright zones |
|
| 34:39 | . Remember a bunch of holes colonial. But look at the size |
|
| 34:43 | the holes well below a millimeter They're just filled in with nick. |
|
| 34:47 | . But that they would have been porosity at the time of deposition. |
|
| 34:52 | right, everybody clear about the bracket . Then the second group of potential |
|
| 35:00 | that creates this plating morphology are the odds And Osterc odds are relatively tiny |
|
| 35:08 | that had two valves. Okay, again, they were filter feeders. |
|
| 35:14 | right. And again, the valves not the same size and shape. |
|
| 35:18 | there's no symmetry between the valves. valve is bigger than the other. |
|
| 35:22 | fact, usually one valve overlaps and curves onto the other valve like |
|
| 35:28 | Right, comes like this And these the two valves will come like this |
|
| 35:33 | overlap. All right. And then has a unique micro structure. Prismatic |
|
| 35:38 | where the prisons of calcite are perpendicular the length of the shell. |
|
| 35:43 | if you look at the shell, all these prismatic calcite crystals. We |
|
| 35:48 | their heimat calcite again, to begin all the modern forms uh seem to |
|
| 35:53 | that they're mostly marine, but they be fresh water. So, think |
|
| 35:58 | you asked me yesterday if you could these lakes, you can these can |
|
| 36:03 | in lake deposits, Right. And can actually be they can actually make |
|
| 36:07 | the reservoir of a lacklustre in Can be the reservoir faces of a |
|
| 36:13 | customer. And play. We're not to talk about the custom plays because |
|
| 36:18 | not marine. But but um but is there. Well, I will |
|
| 36:23 | you the detailed bibliography that has a for the customer and carbonate place. |
|
| 36:28 | right. So, these go back the lower paley's like they still exist |
|
| 36:33 | . This is the the cartoon that the the forms and the size. |
|
| 36:39 | can see these are all relatively tiny . And then two valves. But |
|
| 36:44 | bell records on the other. That's morphology for an ostrich cod the small |
|
| 36:51 | and that record margin. And then you look at the micro structure, |
|
| 36:55 | as well preserved prismatic micro structure. , here's here's an example in thin |
|
| 37:01 | . Look at the scale. That's 100 microns. So this is about |
|
| 37:05 | millimeter this way. See the plate . And then there's the recurve |
|
| 37:11 | So that right off the bat tells that's an Oscar card, because you |
|
| 37:16 | of the other valve organisms show And then he would have well preserved |
|
| 37:21 | micro structure. Okay, next group . And there are two types of |
|
| 37:36 | types of models listed here. The that we mostly encounter in the rock |
|
| 37:41 | in shallow marine settings are bivalves and pod. It's all right. |
|
| 37:45 | we'll talk about the bivalves first and also called pearlescent pods. These are |
|
| 37:50 | the clamshells and oysters and things like . And then you probably know the |
|
| 37:57 | , right? That occur in deeper . Things like cephalopods and belem |
|
| 38:01 | All right, And we're going to nautilus lloyds. And I'm gonna ignore |
|
| 38:07 | . Alright, Because they occur in deeper water and the deeper the |
|
| 38:12 | the bigger they get. All So, they're useful from that standpoint |
|
| 38:15 | you're working really deep water settings, size of the floater tells you something |
|
| 38:20 | the depth of the water in a sense, we're going to focus in |
|
| 38:24 | these because this is mostly we encounter our overall shallow marine successions and carbonate |
|
| 38:31 | . So, let's start with the . Alright. And bivalves meetings two |
|
| 38:35 | . Right? One valve on each playing The symmetry now is between the |
|
| 38:39 | because both valves are identical size and . Okay. And that's true for |
|
| 38:45 | of the most of the bivalves. there are two exceptions. And the |
|
| 38:50 | one is the oysters that you're familiar . Right. One valve is bigger |
|
| 38:54 | the other. All right. And if you play the cretaceous, you |
|
| 38:59 | to be aware of these. This form of uh bivalve called the |
|
| 39:05 | All right. And some of the were the size of my fist. |
|
| 39:10 | of the rudest were the size of leg. And they contribute to the |
|
| 39:14 | of build ups during the mostly during middle and upper part of the |
|
| 39:19 | And they were bivalves because they had lower bigger valve. And then a |
|
| 39:25 | capping valve on top that they used filter feeding. All right. And |
|
| 39:30 | the capping valve breaks off and disappears you're just left with the lower bigger |
|
| 39:35 | . So that is that is the in terms of the symmetry. |
|
| 39:41 | And then with respect to the micro , most mollusk, our magnetic. |
|
| 39:48 | , the exception would be the oysters are cal acidic today and have been |
|
| 39:53 | citic through the mesozoic. And the are mostly or a genetic but there's |
|
| 40:00 | that are schizophrenic. They had shells were both the reaganite and calcite. |
|
| 40:07 | . Go figure. So I'll show this in a minute. And when |
|
| 40:11 | magnetic, all the magnetic micro structures these bivalves again are the is this |
|
| 40:17 | process? Similar micro structure. We a zone where the crystals are in |
|
| 40:23 | one way and then the next the crystals are completely different orientation. |
|
| 40:27 | the classical cross the miller micro Right? So you're all familiar with |
|
| 40:33 | modern forms of of bivalves. You've seen him on beaches and stuff |
|
| 40:38 | that washed up. Most most bivalves filter feeders. One Not all, |
|
| 40:46 | , I guess I guess they all . I don't know of any that |
|
| 40:51 | . All right. And then and section the micro structure, one is |
|
| 40:57 | a magnetic would be this classical across miller micro structure. See how the |
|
| 41:04 | structure varies in orientation from one layer the other within that overall shell |
|
| 41:12 | Alright, so that's sort of classical the for the Iraq genetic mollusk. |
|
| 41:17 | then the calcium forms are either prismatic the shell goes like this and it's |
|
| 41:23 | up of prisons of calcite. They like that or it's a laminated micro |
|
| 41:28 | . Like I showed you for the pods. Okay. And then I |
|
| 41:33 | the rudest and we'll talk about rudest complexes when we get to our plate |
|
| 41:36 | discussion later. But they're all different of rudest and different morphology is different |
|
| 41:43 | and different skate and the one that's is the two castles here you see |
|
| 41:48 | a court serve a corkscrew morphology. is the schizophrenic form I was talking |
|
| 41:54 | and like it couldn't decide how to . Also couldn't decide whether to precipitate |
|
| 41:58 | reaganite or cal sites have precipitated both a shell structure sort of interesting. |
|
| 42:05 | a lot of the rudest have internal to begin with. And of course |
|
| 42:12 | mostly rag genetics. So they get crystallized or dissolved out. Um So |
|
| 42:18 | you look at like the schizophrenic route this is a thin section through the |
|
| 42:22 | Kasid, you can see the shell , The inner layer is highly re |
|
| 42:27 | calcite, that's inferred to be the magnetic layer and then the outer layer |
|
| 42:32 | still preserved. You can start to crude lamination there. That's the calcification |
|
| 42:36 | part of the shell. Okay. then notice this example is associated with |
|
| 42:43 | these little millimeter scale multi chambered, critic benthic. Foraminifera. Okay, |
|
| 42:51 | a lot of times the, you , the bigger shells look like |
|
| 42:54 | but a lot of times the shells down into smaller pieces. And what |
|
| 42:58 | to these smaller pieces when they sit the sea floor. They get me |
|
| 43:02 | . Remember that discussion yesterday about Mick envelopes and the Mc, right envelopes |
|
| 43:09 | . And then the original rag genetic either dissolves out or re crystallizes to |
|
| 43:14 | safari calcite. So this is a breakdown product of any Iraqi knittig |
|
| 43:21 | whether it's a bivalve or a gastro or a floater. Okay, This |
|
| 43:26 | what it's going to break down to the sea floor. If you don't |
|
| 43:29 | micro ties the whole grain. If you completely maker ties it, |
|
| 43:33 | you call it a p lawyer, kristen grain, depending on the more |
|
| 43:37 | depending on the shape of the Okay. And then gastro pods. |
|
| 43:44 | are grazers. You probably have eaten , right, sued? Maybe |
|
| 43:52 | Right, Actually, not that It just sounds bad, but uh |
|
| 44:00 | . You mask everything with butter and , Right? So that's the that's |
|
| 44:04 | way to eat them. Anyway, gastric pods are these grazers. And |
|
| 44:09 | , the scale of these things can tiny little things like this. And |
|
| 44:12 | find on tidal flats today to the horse conch shells of this scale. |
|
| 44:19 | . And uh what's unique about the pods is they have this central supporting |
|
| 44:26 | . It's called the column ella and it. The structure worlds okay, |
|
| 44:32 | it's all open for space, and where the organism lives. Okay, |
|
| 44:36 | sort of lives in there and then out one end to push itself |
|
| 44:40 | And so, you know, depending your angle of cut. If you |
|
| 44:44 | it uh longitudinal like this, this what you would see internally all open |
|
| 44:49 | space. If you cut it this , he would pick up that, |
|
| 44:54 | little support structure that runs down part the middle. Of course, if |
|
| 44:57 | cut it on the edge, you see completely different uh more of a |
|
| 45:02 | what looks like a segment of ferocity because you're cutting uh part of that |
|
| 45:08 | structure. Now, you can see things go back to the camera and |
|
| 45:13 | you would expect, most mollusc are and which means they live on the |
|
| 45:17 | floor and they graze their feeding on . But you should know that going |
|
| 45:23 | the way back to the camera, been a floating variety of snails called |
|
| 45:29 | pods. All right. To live deeper water, but not in deep |
|
| 45:34 | . Okay, So they're in the for part of the surface waters of |
|
| 45:38 | deeper basins. That's where they And they were reconnect two. |
|
| 45:43 | so that's a floater. So that's a cellphone potter, the bell at |
|
| 45:48 | . Except they hung out at the part of the water column. They |
|
| 45:51 | dive down, dive up like, we think the nahda lloyds and Bolanos |
|
| 45:56 | did. All right, So summer dick. All right. And |
|
| 46:03 | so here's some examples. This is underwater photograph of the tiny needle grazing |
|
| 46:11 | pods. And then here's a cross through modern gastro pod. This has |
|
| 46:15 | on the edge of the shell and why it looks like it's segmented |
|
| 46:20 | but it's actually all connected. All . So there's no actual breakage of |
|
| 46:25 | process system as you whirl around that support system. Right? And then |
|
| 46:31 | at the thin section the beautiful cross micro structure here. Just like what |
|
| 46:35 | showed you for the for the Okay. And then different cross sectional |
|
| 46:43 | here. But in the place is . So now you hear you use |
|
| 46:47 | morphology of this fragment to identify this a gastro pod. Right? Because |
|
| 46:51 | can see the central support structure. what's missing here? Now, you |
|
| 46:57 | see the cross the miller micro structure this has been altered by di genesis |
|
| 47:02 | been re crystallized as part of calcite that destroys that crossed the miller micro |
|
| 47:08 | . All right. All right. guys doing okay, Let me get |
|
| 47:16 | this. And we'll take our 15 break. And I got a few |
|
| 47:21 | groups to go through. So the group would be the peripheral to or |
|
| 47:25 | . All right. You're all familiar the bath sponges right there soft |
|
| 47:30 | but they're actually the tissue is supported little speckles. And uh sponges are |
|
| 47:37 | for being filter feeders. Right? have a usually a central open, |
|
| 47:41 | canal and then a bunch of side that feed that these are bottom attached |
|
| 47:47 | . Um They produce speckles. And they are also known to be |
|
| 48:00 | us for the whole body fossil is Karius, but that's relatively rare. |
|
| 48:05 | if you work the permian and you should be aware of these calculus |
|
| 48:12 | that were coral like in terms of hardness. But but they were sponges |
|
| 48:17 | right. And then there's a thing a cal suspension occurs in the cretaceous |
|
| 48:21 | looks coral like. And uh it a sponge as well. But most |
|
| 48:27 | what we encounter in the rock record the spirituals that support the tissue of |
|
| 48:32 | sponge. Alright. And those speckles be calculus or solicitous. And the |
|
| 48:38 | rule of thumb is the Calgary speckles associated with shallow water and the salacious |
|
| 48:45 | are associated with deeper water. That's general rule of thumb. But there |
|
| 48:49 | exceptions. You can have shallow water that also produce salacious spiritual. |
|
| 48:56 | and you can see these things go to the lower paleozoic, they actually |
|
| 48:59 | a role in developing some of the ups that we see in the upper |
|
| 49:04 | and lower Mesozoic? Here's the cartoon today, If you snorkel on any |
|
| 49:10 | reefs, you've seen different growth forms the branch does sponges or you've seen |
|
| 49:16 | big barrel or base like sponges, ? With the big central opening, |
|
| 49:23 | ? So they have a central canal then side chambers that they were, |
|
| 49:26 | just filter feed seawater through there and eat what's in the water all this |
|
| 49:33 | supported by speckles. So when these die, those vehicles become part of |
|
| 49:37 | sedimentary environment. And this is what speculum look like and essentially what they |
|
| 49:43 | like. Her fishhooks, basically. what else do all these speckles eventually |
|
| 49:49 | if you follow a speculum, it does what tapers out. Right? |
|
| 49:56 | you're producing an elongated fragment. But key is to see if it tapers |
|
| 50:01 | not. If the tapers, it to be a sponge pickle. If |
|
| 50:05 | never changes the diameter, then there's some other spine related to BRAC ipod |
|
| 50:12 | a kind of term that they use local motion. All right. So |
|
| 50:17 | what's unique about the sponge pickles. always taper if you catch the right |
|
| 50:22 | , right? Sometimes you don't catch right view. And then the other |
|
| 50:25 | that's interesting is they have a triple preserved, right? They branch out |
|
| 50:30 | a triple junction. And sometimes you catch that. And thin section. |
|
| 50:35 | right. And sometimes you can see trying to see here if there's actually |
|
| 50:41 | tapering. I don't see a lot tapering on these fragments. All |
|
| 50:45 | But a lot of these speckles also a central opening. See that in |
|
| 50:49 | thin section here. And so if cut the spine, the speculum story |
|
| 50:53 | this, you get a cross sectional that looks like this or looks like |
|
| 50:58 | . Okay, so that's the that's unique to the sponge vehicles. All |
|
| 51:04 | . And so these example this example , They're all cal Karius, here's |
|
| 51:08 | example in the pennsylvania where they're all . The problem with the mineralogy these |
|
| 51:14 | is that the cal curious ones can out and then get filled in with |
|
| 51:20 | . The calcifications can dissolve out and filled in with silica. So don't |
|
| 51:24 | ever take the mineralogy necessarily to be primary mineralogy. It's very difficult to |
|
| 51:30 | . Okay, I think, you , maybe from your own experience that |
|
| 51:35 | salacious sponge vehicles are very unstable, ? It's open and silica, which |
|
| 51:42 | that during shallow burial that stuff will and then can migrate and then re |
|
| 51:49 | . And that's how we create some the turk modules that you see associated |
|
| 51:53 | sedimentary sequences, both carbonates and Okay. Usually that church is sourced |
|
| 52:00 | the breakdown of sponge vehicles. let's finish up with the uh cal |
|
| 52:09 | algae. Uh we have different different colors, depending on what they |
|
| 52:17 | like when they were alive on the floor, what we used to call |
|
| 52:21 | green algae. Now, we're not to do that anymore. The biologists |
|
| 52:25 | reclassified these organisms as cyanobacteria. but everybody falls back into calling this |
|
| 52:32 | blue green algae, but it really a blue green bacteria. Alright. |
|
| 52:38 | so these play a role in creating strong metallic fabric we're going to talk |
|
| 52:42 | in a minute and then we have algae and green algae And these are |
|
| 52:47 | different forms I'm going to talk about then a couple of other related |
|
| 52:51 | Golden brown algae. They create these structures or little tiny wheel like structures |
|
| 52:57 | vocalist. And then Phil Lloyd algae is a unique organism limited to the |
|
| 53:05 | and permian. Alright, so you worry about these things being around if |
|
| 53:09 | work those aged sequences. Okay, let's start in. Let's start out |
|
| 53:14 | the santa bacteria. You're asking about star metallic fabric? All right. |
|
| 53:19 | is the stream satellite? It's a created by the entrapment of sediment by |
|
| 53:24 | santa bacteria. Alright. In shallow or on tidal flats where they're only |
|
| 53:31 | flooded. They can't grow vertical Right? So they are flat |
|
| 53:36 | And so and that kind of setting produce the laminated Mr melodic fabric. |
|
| 53:43 | ? And then if you're underwater they go vertical. They make what we |
|
| 53:49 | kilometer streetlights. And then those things coalesce into bigger scale structures. All |
|
| 53:55 | . And I'll show you some modern of this in a minute. And |
|
| 53:59 | yesterday we called the unattached form of fabric unoccupied. Right? We treated |
|
| 54:04 | as a non skeletal grain. All . Now, what's the key control |
|
| 54:11 | on the distribution of santa bacteria? want to live where they don't get |
|
| 54:16 | . Okay? And they can't live deep water because sino right? Means |
|
| 54:23 | the blue green forms need light Okay. And so that's why today |
|
| 54:31 | in the rock records from satellites are in fan of mesozoic and carbonates. |
|
| 54:37 | from Cameron onto the today. They're to unique, restricted de positional |
|
| 54:44 | Right? Where we have either high or we have situation where um the |
|
| 54:51 | is so great that nothing can eat . Okay. Otherwise this stuff will |
|
| 54:57 | to grow in any other environment but be grazed by gaster pots to be |
|
| 55:01 | by the condoms we talked about and remove from that environment. Okay, |
|
| 55:08 | let me show you some examples This is a a slab firm carboniferous |
|
| 55:15 | is mississippian Pennsylvanian age carbonate. And can see what would you look forward |
|
| 55:22 | the smell like fabric as you look that layered effect. But you look |
|
| 55:26 | a situation where the layers are higher the angle of repose. Right? |
|
| 55:31 | that tells you this is not All fabric this is organically bound |
|
| 55:36 | Okay, You can't can't do that a high angle unless you're binding |
|
| 55:43 | you're binding this settlement biologically. so these are the these very low |
|
| 55:48 | formality features here. A couple examples the modern. All right. Uh |
|
| 55:55 | you find stuff like this in Shark in western Australia. These are the |
|
| 56:00 | stromatolites and and all the modern examples associated with high energy analytics sands. |
|
| 56:07 | so the reason for that is because rippled sands effectively keep the gastro pods |
|
| 56:13 | of this setting. So they can't on the sound of bacteria that colonize |
|
| 56:18 | the surface of these structures and traps is to get thrown up by |
|
| 56:22 | Okay, so that's why these these thrive in these high energy environments. |
|
| 56:28 | ? So you're even a restricted title setting or you're in a subtitle high |
|
| 56:32 | setting like this or you're in a setting where the water quality is so |
|
| 56:38 | that the only thing that can live are cyanobacteria. Okay. That's why |
|
| 56:43 | not pervasive in terms of their distribution in marine settings. Yeah. All |
|
| 56:51 | . And then the red algae um algae have a sort of a reddish |
|
| 56:59 | color when they were alive on the floor. There to morphology is there's |
|
| 57:03 | encrusted morphology which is higher energy And then there's the branch morphology where |
|
| 57:09 | organisms grow as little branches. All . And sometimes they grow, one |
|
| 57:15 | top of the other is branched um . So, that's what you look |
|
| 57:22 | . First on a gross sense and verify this with the micro structure. |
|
| 57:26 | micro structure is is referred to as um ridiculous or sell like micro |
|
| 57:37 | It's basically little tiny pores with little . It looks like a bunch of |
|
| 57:43 | cells. Alright, that make up branches or the in clusters and and |
|
| 57:48 | it has a brown color preserved. right. So here it is in |
|
| 57:51 | section. This is one of fragments a branch red algae. You can |
|
| 57:57 | the sort of layered but cellular structure then the light brown color is very |
|
| 58:04 | . All right, So this is modern example. You go back to |
|
| 58:08 | rock record. Go back to the paleozoic things look just like this. |
|
| 58:12 | , this fragments look just like And of course other morphology is the |
|
| 58:17 | morphology. So on refill systems, you have a hard substrate developed, |
|
| 58:22 | expect there to be red algae. not uncommon to go from a |
|
| 58:26 | Like you see here two red But you can only do that if |
|
| 58:31 | coral dies 1st. Right? None these living organisms can be Colonised unless |
|
| 58:38 | kills him 1st. Right. Another attacks them. Or you know, |
|
| 58:43 | a solemnity kick that kills him. there's a cold temperature. The fact |
|
| 58:48 | kills them. All right. But , what are you seeing this |
|
| 58:52 | You can very vaguely see that laminated micro structure. That's the ridiculous fabric |
|
| 59:00 | I think I talk about in the , cheek. Okay. Yeah. |
|
| 59:04 | then the next group would be the algae. Alright, again, I |
|
| 59:09 | yesterday there's a small percentage of of algae today that are calculus. I |
|
| 59:15 | the mud producers yesterday that secrete the needles of a reaganite. But there |
|
| 59:22 | other plants that were free growing uh live first live in places as isolated |
|
| 59:29 | and other places like reefs to actually these little colonies. But there too |
|
| 59:36 | groups, the Cody, asian green or would dominate Mesozoic and younger systems |
|
| 59:41 | exist today. And they produce little like this where the branches are made |
|
| 59:46 | of little palm shaped pieces alright of carbonate. But each of those pieces |
|
| 59:53 | like this in terms of micro that's the swiss cheese micro structure I |
|
| 59:57 | talking about on the Cici. it looks like a piece of moldy |
|
| 60:03 | cheese, looks like you took a of swiss cheese and from the back |
|
| 60:06 | your refrigerator and forgot about it for couple of months. You pulled it |
|
| 60:10 | , it's good brown, greenish brown with all these holes. Well that's |
|
| 60:16 | what the internal micro structure of of Cody ation. Green algae looks |
|
| 60:21 | So very, very easy to And then if you work the |
|
| 60:26 | you need to know about the Dasa green algae, similar plant like structure |
|
| 60:31 | the branches except the, the branches a little bit differently. They have |
|
| 60:35 | central opening and then little side pores come off of that. Okay, |
|
| 60:40 | again, we think all of these were principally Iraq genetic to begin |
|
| 60:44 | So they're going to be prone to re crystallization. So let me just |
|
| 60:49 | you some examples. Right, so is our modern common form of Cody |
|
| 60:55 | green allergies. The species is called Alameda. Alright and Hala media goes |
|
| 61:01 | the way back to the lower part the Mesozoic And it's a prolific sand |
|
| 61:08 | for the same reason we talked about , these plants only lived for a |
|
| 61:11 | months, then they die, they replaced by another plant. The rapid |
|
| 61:16 | allows you to produce a tennis sediment from this mechanism alone. Right? |
|
| 61:21 | bunch of sand sized pieces of swiss material. But that's only part of |
|
| 61:27 | story because what will happen is that will quickly break down into finer silt |
|
| 61:31 | mud size material. So it actually contribute eventually to finer grain carbon a |
|
| 61:38 | . All right. So here's the section. You can see this is |
|
| 61:41 | swiss cheese morphology or micro structure is about you look for the brown |
|
| 61:47 | You look for these holes that are distributed like you'd see in swiss |
|
| 61:51 | Okay, very easy to identify. you see it easy to pick |
|
| 61:56 | Right. And then what's this here we just talked about? What kind |
|
| 62:02 | algae? Green red read, this red algae, right. With that |
|
| 62:13 | cellular micro structure. And then this not analogy. This is actually a |
|
| 62:22 | of any kind of term. All , right. The spines of economy |
|
| 62:27 | they use for locomotion and have a canal. And then the side pores |
|
| 62:32 | come off of that. And you prove this is a kind of her |
|
| 62:35 | going, we're at cross Nichols now the ferocity is black. If you |
|
| 62:40 | the stage 90°, this whole grain would black, right, that's unit extinction |
|
| 62:46 | would prove that's an accounting term Okay. And then the dashiki clad |
|
| 62:52 | algae looked like this example in thin . This is a longitudinal cut through |
|
| 62:57 | of the branches. You can see central opening and then the little side |
|
| 63:01 | that come off of that uh the is highly re crystallized. A spar |
|
| 63:06 | , that's why it's uh white color . If you look down the axis |
|
| 63:11 | this, he would see this view here. So here's the longitudinal cut |
|
| 63:17 | the opening is filled with calcite Here's the trans verse cut, looking |
|
| 63:22 | the axis. Okay. And highly re crystallized. In fact some |
|
| 63:26 | the stuff even dissolved out because it's magnetic. But this is that prolific |
|
| 63:32 | producer in the upper paleozoic. So , if you work um Mississippi and |
|
| 63:38 | permian age carbonate, you expect to in certain environments. Lots of domestic |
|
| 63:44 | green algae. Alright now, to up here, there's a couple of |
|
| 63:49 | forms that they need to introduce you uh there's a type of of modern |
|
| 63:57 | a cloud green algae called as a area. It looks like this |
|
| 64:02 | So these are little branched features with little cup at the end. The |
|
| 64:08 | name is mermaids wine cup. Okay why are these important to the story |
|
| 64:15 | , they only lived for a few and then replaced by another plant. |
|
| 64:19 | what they do two or three times year is they load up the poor |
|
| 64:25 | in these cups with little reproductive cysts are called calcite spheres. And they |
|
| 64:30 | those calcium spheres To the environment of two or 3 times a year. |
|
| 64:36 | . And so this is a modern . This is what the reproductive system |
|
| 64:40 | like. This is a modern analogue the paleozoic calcium spheres that look like |
|
| 64:47 | little circular features just a few 100 across. For scale. With a |
|
| 64:53 | critic test. This is not due mechanisation. This is what they actually |
|
| 64:59 | . And this is cal siddiq. all the paleozoic calc spheres are cal |
|
| 65:07 | . Alright. Even though the modern today, is there a genetic. |
|
| 65:11 | right. But these are interpreted in rock record to be reproductive cysts related |
|
| 65:15 | similar types of green algae. And then you need to know when |
|
| 65:21 | get into the Mesozoic, we have advent of our politic. Remember our |
|
| 65:27 | for um And if we come into , well what also comes into play |
|
| 65:31 | pelagic calc spheres. So in other , some of the algae actually lived |
|
| 65:36 | in deeper water in the upper part the water column and then release these |
|
| 65:40 | cyst into that deeper water setting and look like this are comparable size and |
|
| 65:47 | to what I just showed you in paleozoic. Except look at the if |
|
| 65:52 | look at the outer part of the , it's light colored. Right. |
|
| 65:56 | can see that. I think here the red arrow is. That's that |
|
| 66:01 | calcite mineralogy identical to the mineralogy. I showed you for the plankton |
|
| 66:07 | I'm an effort. Okay, So you see a sample like this in |
|
| 66:10 | rock record in the Mesozoic, completely by calcite spheres. This is not |
|
| 66:17 | to be shallow water. This is be a deeper water setting. |
|
| 66:22 | Because they wouldn't overwhelm a shallow water . They would be mixed in with |
|
| 66:27 | shallow water constituents. Right. All . So, we'll build on this |
|
| 66:33 | we talk about chalk reservoirs later. . This is from the austin |
|
| 66:38 | And you'll we'll talk about this All right. All right. And |
|
| 66:42 | the filling algae I mentioned this produces that have a potato chip like |
|
| 66:48 | The philadelphia gee, nobody really knows it is. So, it's called |
|
| 66:51 | problematical organism. But most people now starting to think it's related to the |
|
| 66:57 | type of calculus green algae to begin , but it's limited Uh huh. |
|
| 67:03 | a geological age perspective too, the . And permit. All right. |
|
| 67:10 | , if you're not playing the Pennsylvanian . You don't worry about philadelphia gee |
|
| 67:15 | never steam in any other sequences. right. And what's what's interesting is |
|
| 67:20 | skipped over diagram in your notes. to show you what put some people |
|
| 67:24 | it was the morphology. Some people these things are sort of grow upright |
|
| 67:29 | a cabbage head with a bunch of . Right? Then the calculus leaves |
|
| 67:34 | break off and become part of the . Because when you walk over some |
|
| 67:39 | the build ups that are created by entrapment of the the Mc, |
|
| 67:43 | By Philippe algae. You just see pieces like you see here in |
|
| 67:48 | all these little dark potato chips like are pieces of Phil oid algae. |
|
| 67:54 | , that's what they break down Right? So the body fossil, |
|
| 67:58 | never seen anybody show I preserved body an outcrop. I've never seen that |
|
| 68:05 | our craft o'Rourke or. So, always the pieces. Alright. Always |
|
| 68:09 | fragments and fragments look like this in section. They look very similar to |
|
| 68:15 | of the fragments I showed you for molluscs. And they could be confused |
|
| 68:19 | the mollison, but that's why you to pay attention to the age. |
|
| 68:23 | , if you see something like this their regular to begin with, they |
|
| 68:28 | a mc critized outer part and re or or leech part to the center |
|
| 68:34 | you're in the Pennsylvanian and permian that's likely to be related to fill it |
|
| 68:39 | , not molluscs. Okay, so to keep in mind and then the |
|
| 68:47 | the type of algae would be golden algae that again live out in deeper |
|
| 68:52 | than the upper part of the water because their algae, they need light |
|
| 68:57 | . These algae are so tiny. at the scale here, 1-10 microns |
|
| 69:01 | . They live in this armored ball made up of these little wheel like |
|
| 69:06 | here. And sometimes the coca sphere as it settles down to the sea |
|
| 69:13 | . Or if even if it gets by some organism, it still preserves |
|
| 69:18 | way. But usually everything breaks down little plates And the individual plates, |
|
| 69:23 | , 2, 3 microns across are Coca Colas. Okay. And so |
|
| 69:28 | you look at all the deep sea today, look at all the famous |
|
| 69:32 | deposits in the rock record. You at them a critic matrix. What |
|
| 69:36 | like nick reid matrix and thin When you go to the scanning electron |
|
| 69:41 | level, this is what you You see sometimes the coca sphere the |
|
| 69:46 | commonly you see the coca lists. right. So this is the breakdown |
|
| 69:50 | of golden brown algae and again, are limited to Mesozoic and younger |
|
| 69:56 | Okay, You don't find these in paleozoic. All right. And then |
|
| 70:04 | so you know, I put in pictures here of uh what's called tuba |
|
| 70:08 | and you don't worry about tube of which has actually been renamed to shame |
|
| 70:13 | by some people. But you only about tube affinities. If you work |
|
| 70:19 | or Triassic reef complexes. So if go to the Guadalupe Mountains and look |
|
| 70:24 | the Permian reef complex there? This a slab of that reef. You |
|
| 70:27 | see the white fabric here. That's affinities. This is what it looks |
|
| 70:33 | in thin section. We don't know it really is. All right. |
|
| 70:37 | it's another problematical organism, but we it's, uh, in a cluster |
|
| 70:42 | to grow off of itself to create framework that leads to reef development in |
|
| 70:47 | permian and Triassic so that we don't what it is. And so that's |
|
| 70:52 | . I'll just show you the Okay. And then the last slide |
|
| 70:57 | list a lot of the organisms I about. The thing you want to |
|
| 71:00 | in mind again is what's the starting for these organisms. Right. That's |
|
| 71:06 | to help us predict what's going to in terms of their preservation or porosity |
|
| 71:11 | . All right. Okay. So a lot of information. I don't |
|
| 71:18 | you to remember 10% of what I've talked about. All right. But |
|
| 71:22 | do want you toward the end of seminar to start feeling more comfortable and |
|
| 71:26 | least differentiating some of the bigger Right? To be able to tell |
|
| 71:30 | different about a bracket pot from a , right. How's the coral different |
|
| 71:35 | a storm atop roid and then some the environmental significance of what we've talked |
|
| 71:40 | , right, That's really perhaps more . Right. What were some of |
|
| 71:44 | open marine indicators we talked about corals ipod's kind of terms, right? |
|
| 71:52 | of the stream atop rides live in marine settings. These are kinds of |
|
| 71:56 | that help us reconstruct our de positional , right? Because that's always our |
|
| 72:00 | job. When we go to our , our core is trying to figure |
|
| 72:03 | where do we drill into or where we looking on the basin within the |
|
| 72:09 | . Right, Okay. So you , there were no notes for |
|
| 72:14 | You people published books. There's a volume of treat us right to go |
|
| 72:20 | all of these groups and I've referenced , the one, you know, |
|
| 72:25 | you get into this later, especially looking at trying to recognize fabric and |
|
| 72:31 | section, you want to go to . Get that a PG book. |
|
| 72:35 | , bye bye. Shoal. A that talks about a pG memoir |
|
| 72:40 | It's a colour atlas of all these types to skeletal, non skeletal and |
|
| 72:47 | says a lot of what I but in more detail. Okay, |
|
| 72:53 | got questions before we break. All , well, let's take our 15 |
|
| 72:59 | break and We'll come back in 15 . About 10. About 10 after |
|
| 73:16 | . Yeah, yeah, yeah. thing on the agenda is lecture |
|
| 73:37 | which is supposed to be the first for Saturday August 28, a brief |
|
| 73:43 | on sedimentary structures just to quickly introduce to the primary and secondary or what |
|
| 73:50 | call deposition and post deposition of sedimentary . And then I'll take all of |
|
| 73:54 | information and try to apply it to discussion of deposition environments or die genetic |
|
| 74:02 | and products. Okay, so the slide shows you the breakout of the |
|
| 74:09 | types of what we call deposition or contemporaneous sedimentary structures. Okay. And |
|
| 74:15 | not going to show examples of all this, but I'm going to show |
|
| 74:19 | of most of this on the And then we'll come back and talk |
|
| 74:23 | the post oppositional structures which are related die genesis. And so that would |
|
| 74:28 | the several exposure fabrics like cars sold , soil crust, scope, eyes |
|
| 74:34 | fruit cast and then pressure solution Okay. Say says I'm recording. |
|
| 74:50 | says I'm recording, I mean my red lights flashing. Yeah, I |
|
| 75:02 | we'll find out. Okay, so start with the penny contemporaneous or Cindy |
|
| 75:16 | sedimentary structures and this is a list the ones that I'm going to show |
|
| 75:20 | examples up here and just make a comments and I'll build on this more |
|
| 75:25 | detail as we go along. But , to start with illuminations. |
|
| 75:31 | And first example of parallel examinations, example from the devonian and core. |
|
| 75:37 | how do you produce this kind of ? You produce this kind of fabric |
|
| 75:41 | settle out, right. This is that comes into the water column and |
|
| 75:45 | . And then by gravity, just out and produces the parallel stratification. |
|
| 75:53 | ? So these are pretty classical fabrics to that setting. So what's implied |
|
| 75:59 | is quiet water obviously. Okay. what else is implied? Why is |
|
| 76:05 | preserved? In other words? Why Why isn't the stuff furrowed? |
|
| 76:18 | Yeah. You had to do something the water quality in order to eliminate |
|
| 76:23 | borrowers to preserve this laminated fabric. . Mm hmm. Docs. |
|
| 76:30 | this is a world class source rock Western Canada, the di Verney |
|
| 76:34 | Um Yeah. And the interpretation is this is an anoxic basin. So |
|
| 76:40 | content was so low on the sea that you couldn't even support borrowing |
|
| 76:45 | Okay. And then contrast that with other kind of stratification. The cross |
|
| 76:50 | , like you see your in the to grain stone from the Jurassic, |
|
| 76:55 | obviously reflection of high energy conditions on sea floor. It's a cross sectional |
|
| 77:00 | of what would be rippled sands on surface of the sand body related to |
|
| 77:05 | would be herringbone cross stratification where you the bedding set like this where one |
|
| 77:11 | goes like this and then one layer back on itself. That's the reversing |
|
| 77:16 | effect. So, sometimes you'll see in these tide dominated Greenstone systems. |
|
| 77:23 | right. But these are this is directional cross stratification. And then when |
|
| 77:29 | don't things are not high energy. when things are not anoxic or hyper |
|
| 77:36 | , What's the common fate for all in shallow or deep water. The |
|
| 77:40 | fate is by a probation. All . And by on probation is created |
|
| 77:45 | burrowing shrimp and worms and molluscs. we've talked about already. And they |
|
| 77:50 | two things. They destroy any primary . And secondly, they do what |
|
| 77:56 | destroy the organic potential, right? eat organic material or they pump in |
|
| 78:01 | water to oxidize the organic material. right. So these are some of |
|
| 78:06 | trace fossils of the burrowing shrimp. . And here's another example of the |
|
| 78:14 | related to the shrimp. Alright. here, what's happened to some of |
|
| 78:18 | borough Phil has been partially dramatized here of the better permeability associated with the |
|
| 78:24 | fill. So essentially in carbonates. we say is that if we don't |
|
| 78:30 | preserve stratification, either plain or horizontal or cross stratification. If we don't |
|
| 78:38 | that in our cropper core, we that succession has been borrowed and probably |
|
| 78:43 | many times over like a blender. like a blender. Okay. Because |
|
| 78:48 | what these organisms do. They're always to eat the organic material. All |
|
| 78:54 | . And then the next group of structures would be the end thrusters. |
|
| 79:00 | morphology. We talked about this already corals and red algae storm atop |
|
| 79:05 | uh, this is a piece of coral. And you can see this |
|
| 79:09 | a bumpy form of red algae This is a common fate, this |
|
| 79:14 | what you expect to happen to these hard skeletal grains after they die on |
|
| 79:20 | sea floor. If they're not re by a living coral, then they're |
|
| 79:24 | to be encrusted by something like red . Alright. And then we talked |
|
| 79:31 | boring and in crustaceans. All this is a common fate for |
|
| 79:36 | these harder structures like corals or larger structures, they sit on the sea |
|
| 79:41 | , they're going to be attacked by . And we talked about what they |
|
| 79:45 | and how they do it yesterday. . Physical or chemical action or a |
|
| 79:51 | of both to create these holes. talked about the boring sponges. This |
|
| 79:57 | a piece of coral pulled out of marine environment with living boring sponges. |
|
| 80:03 | This is uh the red is all sponge and this is the critter that |
|
| 80:08 | acid in order to dissolve the Alright. And what it does is |
|
| 80:14 | uses a pseudo podia. He eats into the rock and it grabs these |
|
| 80:18 | chips. These little distinctive silt sized and creates them by dissolution and pulls |
|
| 80:25 | through its body and then excretes it the environment of deposition. And they |
|
| 80:31 | like this. And they are very . You see the scallop nature |
|
| 80:36 | this is always produced by a boring , but again, these are tiny |
|
| 80:40 | . It would be part of the matrix, you would never recognize this |
|
| 80:44 | thin section, you'd have to go the scanning electron microscope to see |
|
| 80:49 | And then one last example in the to show you the molly shell again |
|
| 80:54 | a sponge boring filled in with little see those calcium spheres, little circular |
|
| 81:01 | that we talked about, The reproductive , the algae. Okay. And |
|
| 81:06 | another sedimentary structure, the sin deposition the hard grounds. I showed you |
|
| 81:11 | picture of those and I do with environment yesterday. Looking down on the |
|
| 81:15 | floor, that rocky bottom created by sedimentation of the sand. Well, |
|
| 81:20 | is a piece of that hard ground that photograph from that same area. |
|
| 81:26 | is the definition of marine hard First it is marine cemented. So |
|
| 81:32 | have to demonstrate that the cement that the grains together our marine in |
|
| 81:36 | I'll show you how to do that today. And then secondly it has |
|
| 81:39 | be bored and encrusted. Okay, marine cemented borden encrusted. That's the |
|
| 81:46 | of what we call the marine hard . And so you can see some |
|
| 81:49 | the holes that cut through here. can see some of the n |
|
| 81:53 | This little pinkish thing here is actually entrusting foraminifera, not red algae. |
|
| 82:00 | , and here's a cut through one those hard grounds. Again, the |
|
| 82:05 | pink material is not red algae. the foraminifera that I just showed |
|
| 82:10 | But again, all the holes here reflective that hard substrate created by marine |
|
| 82:17 | . So that's our definition of a hard ground and we have these in |
|
| 82:21 | rock record and we'll talk about their from a strata graphic standpoint later. |
|
| 82:28 | here's an example from the cretaceous that to be visible in a quarry outside |
|
| 82:33 | Austin Corey is filled in now. this is the top of a nude |
|
| 82:38 | body system. You can see the here. And if you look at |
|
| 82:42 | , even with the handle and you see the holes cut across the grains |
|
| 82:46 | cement. So, you know, was a hard structure to begin with |
|
| 82:49 | these organisms board into it. And if you walked on the surface of |
|
| 82:54 | hard ground you would see all the the holes. But then you would |
|
| 82:58 | the n clusters little entrusting mollusk. , so bored and encrusted. That's |
|
| 83:05 | definition of marine. Our grand. usually we do this in overall shallow |
|
| 83:10 | carbonates successions. But we can actually hard grounds in deeper water carbonate systems |
|
| 83:16 | well. Even the chalk deposits around world show hard ground development where you |
|
| 83:22 | see again scalloping and boring and then of the boring with this surrounding |
|
| 83:29 | So, you know that these holes created on the sea floor right in |
|
| 83:32 | to get that sediment into those holes ? It's just that this scale. |
|
| 83:36 | can't see the marine sedimentation. Like can see in a coarser grain shallow |
|
| 83:42 | limestone. Alright, so again, put all this in perspective. I |
|
| 83:45 | want to introduce you these different sedimentary and then geo pedal structure. And |
|
| 83:51 | probably heard of these, right? Shell falls down on the sea floor |
|
| 83:57 | uh like you see here and it gonna always if it fills in, |
|
| 84:04 | going to fill in from the bottom , right? And a G a |
|
| 84:08 | cannot fill in all the way with . Right? Or you never know |
|
| 84:12 | is up direction, but it was filled like you see here, this |
|
| 84:16 | you up direction. So finding geo is very useful if you work full |
|
| 84:21 | and stuff like that, because that you reconstruct what was de positional up |
|
| 84:27 | . Right? Because that can be challenge. And these highly structured fold |
|
| 84:32 | . All right. That's a G pedal structure. And then in some |
|
| 84:35 | our refill buildups associated with things like bright zones. Uh There's a unique |
|
| 84:43 | called strum attacked us. Um I the term bug here and read because |
|
| 84:51 | is an improper use of the term . But let me let me start |
|
| 84:54 | what people think of storm attack. is they think it's a primary fabric |
|
| 85:00 | in a muddy carbon. A It has a flat floor and irregular |
|
| 85:06 | . It's usually filled in to some with settlement. So in a way |
|
| 85:10 | is like a geo pedal. So here you see it in the |
|
| 85:14 | . But people historically have called these bugs. Now I'm gonna introduce you |
|
| 85:20 | porosity classification scheme later today. But there maybe next week I'm going maybe |
|
| 85:27 | month, but oh, a bug a secondary port type. Okay, |
|
| 85:35 | is interpreted the primary. All Yeah. So this is a problem |
|
| 85:40 | the term bug mud loggers call any shaped hole of bug. All |
|
| 85:45 | That's not the definition of a The bug is a secondary poor that |
|
| 85:49 | can't figure out its origin. so these are not bugs even though |
|
| 85:54 | literature describes them as has bugs. , so again, very very limited |
|
| 86:01 | these unique buildups. These, my buildups involving dry zones and cry noise |
|
| 86:06 | things like that. All right. that excuse me then Brescia, there |
|
| 86:11 | two types of Brescia there, the genetic Brett. So we're going to |
|
| 86:15 | about is the secondary sedimentary structure. then there are primary sedimentary brunches and |
|
| 86:23 | some core from west texas in the basin on the Permian. This is |
|
| 86:30 | these are pieces of cemented ah material from different parts of the basin have |
|
| 86:39 | brought in by some mechanism uh probably and gravity flow. Uh and then |
|
| 86:46 | deposit into the basin. So these Brescia class but they're not created by |
|
| 86:54 | . Okay, they are sediment they're layers, marine cemented layers of material |
|
| 86:59 | get reworked and then re deposit somewhere in the basin. And sometimes you |
|
| 87:04 | get good grading like you see here the course of pieces of the base |
|
| 87:08 | then find a Brescia class towards the . These are sedimentary brunches. |
|
| 87:13 | curse has nothing to do with All right. This is a |
|
| 87:16 | All phenomena. I'll put this in with our play types later on. |
|
| 87:20 | right, Yeah. And then there's type of fabric called finessed roll |
|
| 87:26 | which is also a primary port type carbonates. The term finesse tral. |
|
| 87:32 | financial porosity is a poor type. is too big to be explained by |
|
| 87:37 | packing of the surrounding grains. And , what that implies is it something |
|
| 87:41 | open the poor system long enough um be cemented and preserved on the sea |
|
| 87:48 | . Okay, so, finn estelle is actually a primary port type. |
|
| 87:54 | , even though again, a lot the mud lockers call these funny shaped |
|
| 87:58 | here filled with anhydride. They call funny shaped holes. Again vogue |
|
| 88:03 | but when you look at them in section, here's one of the finesse |
|
| 88:07 | , there's no evidence of dissolution. around the edge here, this is |
|
| 88:10 | primary fabric created by something in the holding it open. So what holds |
|
| 88:16 | open? Either trapped there or trapped . Okay? The air comes from |
|
| 88:23 | beaches when away breaks across the Okay. And forces air and water |
|
| 88:28 | the sand. Most of the air water escapes, but some of the |
|
| 88:32 | gets trapped in the sand to create pores. That's one way to make |
|
| 88:36 | the other way to make it in normal critics setting like this is on |
|
| 88:40 | flats. Where where you had Remember the flatline stromatolites associated with the |
|
| 88:47 | flat? Well, when you start bury those just a few inches, |
|
| 88:51 | obviously die and they do what they , right? They give off co |
|
| 88:56 | they give off methane or H. S. And some of that gas |
|
| 89:00 | gets entrapped in the settlement to create ferocity. Alright, so it's both |
|
| 89:05 | port type that we're going to talk later, but it's also considered a |
|
| 89:10 | structure. And here's an example of beach deposit from the place of |
|
| 89:16 | We've got general seaward dipping stratification but preserved all of these holes. All |
|
| 89:21 | holes were created by waves breaking across surface to the beach, forcing air |
|
| 89:25 | the sand. And some of that being entrapped and preserved. Okay, |
|
| 89:32 | this does preserve in the rock So. And then mud cracks. |
|
| 89:37 | gonna talk about title flat systems next , mud cracking is due to |
|
| 89:42 | Right? So when you expose your carbonates, they're going to uh create |
|
| 89:49 | mud crack fabric like you see And uh again, usually that mode |
|
| 89:55 | is also associated with santa bacteria. created the stability of the sediment to |
|
| 90:00 | with, mud cracks are good indicator of of title flatter what we call |
|
| 90:08 | title so restricted that nothing and and exposed periodically that nothing can live there |
|
| 90:16 | cyanobacteria. And these things will preserve the rock creek. Er This is |
|
| 90:20 | on the bedding planes. You can fossil mud cracks preserved. All |
|
| 90:25 | No. And then there's another structure the teepee structure. What happens on |
|
| 90:32 | of these tidal flats or grain Carbonate sand flats, especially in more |
|
| 90:40 | IQ or arid environments where it's less rainfall. You will do what |
|
| 90:48 | will take that sentiment and cement And as you start to cement |
|
| 90:51 | the force of crystallization of those cement causes expansion and creation of these TP |
|
| 90:59 | . Okay. And you know sometimes can do this with uh little roots |
|
| 91:05 | stuff like that pushing layers up but arid climate where there's no vegetation. |
|
| 91:10 | has to be due to force the . Okay, so it's either the |
|
| 91:15 | or agonized cement expanding or it could an evaporated mineral like gypsum is standing |
|
| 91:20 | give you that teepee structure. So are small scale example here from |
|
| 91:26 | Here's the famous big scale example from parking lot at Carlsbad caverns and the |
|
| 91:33 | mountains. Right? These are carbonate buckled up, right to create the |
|
| 91:40 | structure. And you can actually see cement in between some of these buckle |
|
| 91:45 | and it's the expansion of the marines that is thought to cause that buckling |
|
| 91:51 | . Okay. And you can actually some of this teepee structure and core |
|
| 91:56 | seen before where you can actually see layers like this In a 33" diameter |
|
| 92:03 | . All right. And then the , any questions about the primary stuff |
|
| 92:10 | , this is all out of I'll put a context, all of |
|
| 92:12 | stuff later. But I just wanna you to the terminology and then the |
|
| 92:18 | compositional structures are listed here. Uh are related to several exposure and the |
|
| 92:23 | genesis that comes with exposure to fresh and then some is related to pressure |
|
| 92:29 | , which is burial related phenomena. , so let's start with the several |
|
| 92:35 | fabrics. Um If you're in a that is not truly arid where there's |
|
| 92:43 | vegetation. If you have any kind tree or roots associated with your exposed |
|
| 92:50 | , you have the potential to develop cast where the root structure actually gets |
|
| 92:56 | and preserved. You can actually see cellular structure of the roof preserved |
|
| 93:03 | Uh Finding something like this is good that you had longer term several |
|
| 93:08 | You see the problem with a root as it can look a lot like |
|
| 93:12 | borough structure. Right? So how you tell the two apart the diameter |
|
| 93:20 | a borough never changes. Right? the organism doesn't change. But what |
|
| 93:26 | to route as it grows as he off the tree trunk? The |
|
| 93:31 | Do what? Thanks they write, thin or they taper. Right? |
|
| 93:36 | if you see enough of the you should see that tapering effect. |
|
| 93:39 | ? Sort of like like I was about for the sponge pickles, but |
|
| 93:43 | it's related to the to the root then that gets calcified and preserved. |
|
| 93:50 | . And then another key several exposure are these silly Crestor calculates later. |
|
| 93:56 | going to show you what happens with carbonates when they're exposed for more than |
|
| 94:00 | or 10,000 years in a relatively rainy . The carbonate material, the original |
|
| 94:08 | material in this case Angela to grain gets dissolved and then replaced by this |
|
| 94:15 | dense. The critic carbonate. This not deposition all Mick, right? |
|
| 94:19 | is di genetic Mick right. Of mag calcite that replaces that Iraq genetic |
|
| 94:25 | and uh the red or reddish brown is due to aerosol iron that is |
|
| 94:32 | across from the Sahara desert to the . Alright. And it doesn't take |
|
| 94:37 | lot of iron to give you that . All right. So that's a |
|
| 94:41 | color reflecting subway real exposure where you a little bit of iron in the |
|
| 94:46 | and it gets oxidized in the Alright. And so we'll talk more |
|
| 94:50 | this. So across later and then the soil crust, wherever it gets |
|
| 94:54 | by vegetation where roots and joints penetrate into the rock. If you can |
|
| 95:01 | more fresh water down, you have potential to develop cave systems and the |
|
| 95:07 | burial cave systems. What happens to roofs? Sometimes they collapse and you |
|
| 95:12 | what you produce the classical karst related Brescia. Okay. And so this |
|
| 95:21 | the host rock. Again, the grain stone and now the reddish brown |
|
| 95:27 | fabric. That was a replacement fabric the soil crust is now acting as |
|
| 95:31 | cement to create this spreadsheet fabric. , so this is di genetic |
|
| 95:37 | This is what everybody wants to see the rock record to say, I |
|
| 95:41 | cursed, right, my carbonate was and underwent cave development and car |
|
| 95:50 | Maybe. Maybe this is evidence. , I'll show you the problem here |
|
| 95:56 | . But yeah. And then here's couple of ancient examples here from the |
|
| 96:01 | Ellenberger in west texas sort of vision is a famous example of the of |
|
| 96:08 | related fabric where people think the reservoirs related to car certification and uh we'll |
|
| 96:15 | that later when we get to our type discussion. Okay, You see |
|
| 96:21 | of the problems here in the look at the look at the so |
|
| 96:24 | K Phil, right in the previous , it was reddish brown. |
|
| 96:30 | And here it's greenish. Why would be greenish if it's several exposed to |
|
| 96:36 | water. See the problem here, aren't these are this iron bearing |
|
| 96:43 | These are iron bearing in lights and guides that they're greenish because it's not |
|
| 96:51 | . Right? It's reduced. this is the problem with the |
|
| 96:55 | Right. Everybody just hung up on breadth of class. They're not thinking |
|
| 96:59 | how it all relates together. All . If this is truly formed during |
|
| 97:06 | episode, all the iron should be and reddish. Right, sure. |
|
| 97:11 | come back and talk about this in detail. And then pressure solution seems |
|
| 97:16 | lights, whiskey micro style lights. non structured form of pressure solution. |
|
| 97:22 | more typical and democratic carbonates. I'm going to go in this a |
|
| 97:26 | of detail about this later today. then this last fabric here is called |
|
| 97:32 | the modular fabric. And the natural is a combination fabric. It starts |
|
| 97:37 | with a borough fabric. So I you the shrimp borough fabrics earlier that |
|
| 97:42 | that they create the they create that a probation effect. And then with |
|
| 97:48 | barrel and pressure solution superimposed on You produce this classical modular fabric. |
|
| 97:55 | , and this is so typical of water settings. We have bio probation |
|
| 98:00 | then you bury this stuff into deeper deeper water. In fact, some |
|
| 98:05 | this is the famous building stone from the magnetic Oh rosa. You find |
|
| 98:11 | a lot in the hotel's right. lot of hotels have this on |
|
| 98:15 | in their bathrooms and then on the entry lobby floors. This is all |
|
| 98:21 | limestone created by this two phase Right, borrowing early and later pressure |
|
| 98:30 | . Okay, so I just want introduce you to this um Tony any |
|
| 98:39 | ? All this is going to be in more detail in just a |
|
| 98:44 | All right, let me take a break here. Okay, our next |
|
| 98:49 | is um Lecture five on carbonate rock schemes. This is a short |
|
| 98:56 | just to make sure that we're all the same language when we characterize a |
|
| 99:02 | rock. Okay, um The history these classification schemes goes back to the |
|
| 99:10 | back then, both academicians and people oil company research labs, we're all |
|
| 99:17 | coming up with their own classification So Exxon had their own scheme. |
|
| 99:23 | had their own scheme. Ah bob of texas was developing a scheme and |
|
| 99:31 | So what happened was in 1959, pg held their first research conference |
|
| 99:39 | on it was titled the classification of rocks. And out of that came |
|
| 99:44 | first memoir #1 called classification of carbonate . Right? Where all these companies |
|
| 99:51 | some of the university people published their schemes. Okay, So that was |
|
| 99:58 | . And so it's been, you , 50 years and the test of |
|
| 100:02 | , is that the one that has and is most used in industry and |
|
| 100:09 | is the so called Shell classification by Dunham. Alright, so bob Dunham |
|
| 100:14 | a carbon a geologist that worked for research lab in bel air, which |
|
| 100:20 | exist anymore and uh I actually got meet him when I was a grad |
|
| 100:27 | at rice toward the end of his , interesting guy, very creative in |
|
| 100:33 | of his thinking, you could just that from the way he talked and |
|
| 100:36 | way he asked questions and the the why is classification scheme has survived is |
|
| 100:44 | of all, it can be applied all different scales from outcrop to core |
|
| 100:49 | section Okay. And then secondly, terminology has implications for environmental setting and |
|
| 100:58 | potential. Okay, and none of other classification schemes really do that and |
|
| 101:04 | why his system has survived. All , so how do we use |
|
| 101:10 | We use the scheme by asking a of questions and the first question |
|
| 101:15 | do we have any Mick right, our limestone or not, Right, |
|
| 101:20 | what are we trying to do? trying to describe the deposition of fabric |
|
| 101:25 | I think you saw the challenge yesterday lime mud, right? How well |
|
| 101:29 | resolve that question, depends on your of observation. Uh normally when I |
|
| 101:35 | a course like this, I have sets and do exercises to back up |
|
| 101:40 | lot of these lectures and you would at hand sample and not see any |
|
| 101:44 | Right? Then you go to thin , you see Mick right between the |
|
| 101:48 | . So that's the problem in You've got to get to that then |
|
| 101:51 | level to verify whether there's Mick right not. And so we talked about |
|
| 101:55 | significance of Mick ride yesterday. It can form in any carbonate |
|
| 102:00 | but where does the stick? It in the quieter water settings. |
|
| 102:04 | And so that's the first thing you to determine. And then the |
|
| 102:08 | one second point which is more is trying to decide whether it was |
|
| 102:12 | support or mud support to that rock would say great support means that somewhere |
|
| 102:18 | three D enough grains are touching each , enough sand sized grains are touching |
|
| 102:23 | give support to that rock and the right is just filling in the |
|
| 102:27 | Okay, whereas mud support means that mud is taking up the little static |
|
| 102:33 | and any grains you see there are sand sized grains are just floating in |
|
| 102:37 | my critic matrix. Okay. Now that requires that you understand some effect |
|
| 102:45 | grain shape on packing density. And this is why I said you |
|
| 102:50 | to pay attention to the morphology of grains. As I said, spheres |
|
| 102:55 | together differently than a potato chip like . Okay, so this is the |
|
| 103:00 | challenging aspect of the classification scheme. right. And everybody struggles with |
|
| 103:06 | I struggle with this every time I on the critic limestone. Right? |
|
| 103:11 | to decide mud or grain support. right. Uh huh. I mean |
|
| 103:17 | it's a really grainy fabric with just few percent of line mud, then |
|
| 103:20 | pretty clearly grain supported texture. But you get into these mormon critic lime |
|
| 103:25 | becomes a challenge. All right. we'll talk about how you can deal |
|
| 103:29 | that in a minute. All So, the goal here, it |
|
| 103:33 | too just described de positional texture. we can't see deposition of texture and |
|
| 103:40 | carbonate rock because of the adverse effects diet genesis or demonization. Uh And |
|
| 103:47 | used to just throw our hands up say I'll physically describe the rock. |
|
| 103:52 | ? I've got a coarsely crystalline dull done with 20 inter christian ferocity tells |
|
| 103:57 | what the rock is. But it tell you anything about the nature of |
|
| 104:01 | deposition environment right now. You know are the candidates now for the fluorescent |
|
| 104:07 | in the white paper technique that I about. Sometimes we can go to |
|
| 104:12 | altered carbonates and actually see the rally fabric and texture. So, fortunately |
|
| 104:19 | of what we encounter in the rock . We can see the deposition of |
|
| 104:23 | . So you moved down to the line and you ask yourself the question |
|
| 104:26 | these sedimentary components sand sized components or right bound at the time of deposition |
|
| 104:33 | not. Okay. And most sedimentary is not bound at the time of |
|
| 104:41 | . And we're not talking about marine . Okay. We're not talking about |
|
| 104:44 | grounds, we're talking about organic Okay that's what he's talking about. |
|
| 104:50 | it turns out there are only two where you can get what he would |
|
| 104:54 | abound stone that results from that organic . one would be associated with the |
|
| 105:01 | . Right? Either the flat line Colombia small lights and the other example |
|
| 105:06 | be associated with parts of the reefs the reef elements like a coral does |
|
| 105:13 | grows together to create a rigid Right? That would put a hole |
|
| 105:17 | your sailboat. Alright, so parts reefs, not all reefs are solid |
|
| 105:23 | stone. Okay. But some parts the restore brownstone where the framework is |
|
| 105:28 | by the inter growth of the rigid or stream a topper is whatever the |
|
| 105:33 | . Okay if Dunham saw something like , he would call that a bounce |
|
| 105:37 | . Okay. Otherwise everything else is to be unconsolidated and not organically bound |
|
| 105:44 | the time of deposition would have to into one of these other four |
|
| 105:48 | Okay, so you move down to next line, ask yourself the |
|
| 105:53 | is there any line McCormick right in rock or not? If there's no |
|
| 105:59 | , mud or Mick right then by has to be great support and that's |
|
| 106:04 | Donna would call grains done. Okay grain stone has no Mick. Right |
|
| 106:09 | by definition even though in a cross view you may not be seeing a |
|
| 106:14 | of those grains touching, They have be touching back in three D. |
|
| 106:21 | . They have to write if there's mud in the system. So that's |
|
| 106:25 | grain stone. Right? And obviously start off with not the highest ferocity |
|
| 106:30 | but the highest firm abilities Up to 55 Darcy's of Permeability. Okay. |
|
| 106:39 | then you can have a situation where have nick right in the system, |
|
| 106:43 | its brain supported. Right? So what we would call a Pakistan where |
|
| 106:48 | can demonstrate there enough grains there to you the support but you filled in |
|
| 106:53 | or all of that prostate. But Mick, right? That's a |
|
| 106:57 | And so now I think you can some Pakistan's have a few percent like |
|
| 107:02 | and could have better reservoir potential. Pakistan's. All the process filled in |
|
| 107:10 | Mick, right? Would have low potential. So what's evolved in the |
|
| 107:14 | is the differentiation between what people would are low mud pack stones and high |
|
| 107:21 | pack stones. There's no magical cut . Okay, so you it's |
|
| 107:27 | but when you say low mud pack , you want to tell people how |
|
| 107:31 | 5% make, right? 10% right, okay. Or even I |
|
| 107:36 | do that even for the high mud just to let them know. All |
|
| 107:40 | , because you can see below my could have reservoir potential. All |
|
| 107:47 | And then too much supported examples here you have more than 10% of the |
|
| 107:53 | sized grains in the rock, but randomly distributed or floating in the |
|
| 107:57 | That's what he called the wacky Less than 10% grains. He called |
|
| 108:00 | a mud stone. I added the lime mud stone to this diagram. |
|
| 108:07 | , Because of the shale plays because shale, right, you use the |
|
| 108:11 | mud stone and you don't want people miss construe what you've just described. |
|
| 108:17 | ? A limestone, mud stone fabric going to fracture. Right? And |
|
| 108:23 | to fracking a lot different than a . So, and when you do |
|
| 108:29 | , if you encounter mud stones, are incredibly rare in the rock |
|
| 108:32 | by the way you want to modify save lime mud stone. Okay, |
|
| 108:37 | don't need to put lime in front this. I mean, you can |
|
| 108:40 | you don't need to These terms are implied to be carbonate. Okay. |
|
| 108:46 | right. Now, here's where is problem marrying this classification scheme? It's |
|
| 108:52 | here, is this transition between Pakistan Pakistan, Right. And what happens |
|
| 108:58 | a normal environment that's not anoxic or saline? And you've got a lot |
|
| 109:03 | mud deposition? Well, who's invited that environment, the borrowers, |
|
| 109:09 | They're going to come in and they're start reworking that material. Right? |
|
| 109:14 | actually gonna create variability in terms of ? No, I told you |
|
| 109:18 | the shrimp go down. They put chambers, they packed the side |
|
| 109:22 | Of course, your grain fabric. throw the lightweight fecal pellets out the |
|
| 109:26 | . So you can see how there be in a burrow succession. There |
|
| 109:30 | be variability. Right? So sometimes look at a rock or thin section |
|
| 109:35 | part of it looks like it's grand and part of it looks like just |
|
| 109:38 | mud support. Well, it's probably . Okay. And so you say |
|
| 109:43 | right? If you see this you say I've got a political Pakistan |
|
| 109:47 | Pakistan let people know it's bird and it's got this variable texture. |
|
| 109:54 | that's the problem area. Right trying to decide between Pakistan and |
|
| 109:59 | Usually. All right. Now, other thing you can do here is |
|
| 110:02 | can put a whole paragraph of descriptors front of in front of the |
|
| 110:08 | Okay. But the convention is if have let's say you have two major |
|
| 110:13 | types in a limestone, let's say have a grain stone that's mostly analytic |
|
| 110:18 | has lots of P Lloyd's too. way you would describe that would be |
|
| 110:22 | . Little bulajic grain stone. And would tell people who is are the |
|
| 110:28 | grain type. Okay, so the next to the term grain stoner paxton |
|
| 110:33 | be your major grain type in that . Okay. And then you can |
|
| 110:37 | it anyway, you want right color . I mean, colour sedimentary |
|
| 110:43 | whatever you want to put in front it because that's the goal. |
|
| 110:46 | The goal is to convey what you've an outcrop or and the subsurface. |
|
| 110:53 | . Any any questions on this would go through a couple of examples here |
|
| 110:56 | then Obviously all of this gets applied our discussion for the remainder of the |
|
| 111:02 | . Alright. All right, let's look at a couple examples |
|
| 111:06 | We'll start with this first example This is uh big play D shell |
|
| 111:14 | some type. Okay, these turn to be clamshells. All right. |
|
| 111:20 | can see the growth ridges. So, they're only two big robust |
|
| 111:24 | that make growth ridges. Those are ipods and and clam shells. And |
|
| 111:30 | these not just tell you these are . Okay, and then you've got |
|
| 111:33 | darker matrix in between and you can the question now, is who kind |
|
| 111:40 | matrix? This cannot be a grain , agreed. So, what is |
|
| 111:48 | , is it grain support, tax or is it mud support, |
|
| 111:54 | What do you think? Yeah, , looks much supported. Can you |
|
| 112:03 | that? Because you don't see a of grains touching in this in this |
|
| 112:10 | of view. Right, just about calls this much support. So, |
|
| 112:16 | call it a moleskine wacky stone. ? All right, now come back |
|
| 112:21 | this in a minute. Here's another here again, you don't know what |
|
| 112:26 | grain type is but anybody see evidence the morphology of the grain? It's |
|
| 112:33 | . But what else? See See this what's that morphology branching. |
|
| 112:47 | ? So there is some evidence of morphology here. Okay. And more |
|
| 112:53 | this way. And I would surmise you cut it this way you'd see |
|
| 112:57 | that looks like this right, coming you. But we've still got the |
|
| 113:01 | issue here. We've got these sand skull uh grains. They turn out |
|
| 113:05 | be red algae. Branch road But then we've got the matrix in |
|
| 113:10 | . So same issue again. Must support or grand support. What |
|
| 113:17 | you think? So much support Everybody everybody says that because they don't |
|
| 113:24 | a lot of grains directly touching. right. And so both of these |
|
| 113:28 | are artificial rock that we created by modern settlement putting in a box and |
|
| 113:36 | adding epoxy residents of the first example the modern clamshells. So we put |
|
| 113:43 | in a little box added the epoxy which is blue died to give you |
|
| 113:48 | the that's the the epoxy resin was matrix. Okay? But because they're |
|
| 113:55 | in a box they all had to touching in three D. Right? |
|
| 113:58 | all those grains are touching and three . The point is you didn't see |
|
| 114:02 | touching in this two D. Right? This is what you need |
|
| 114:06 | learn about the way things packed This is the way played the grains |
|
| 114:11 | together. They don't touch in a of spots. And that any random |
|
| 114:15 | D. View. And then this is to stick like red algae. |
|
| 114:21 | are not fragments of red algae. are whole red algae. I collected |
|
| 114:26 | off the shore off the beach. live in they live in shallow water |
|
| 114:30 | off the beach and off these caribbean as a band of free growing little |
|
| 114:35 | like red algae. And their they're attached to hard substrate. They're growing |
|
| 114:40 | sand substrate, pick them off the , we put them in a |
|
| 114:44 | Same did the same thing. And is what This grain supportive fabric looks |
|
| 114:50 | and threatened. Random two d. . Okay, so this is a |
|
| 114:55 | , right? And if you read classification scheme, we just replicated with |
|
| 115:00 | Dunham did back in the 50s. right. You can see his examples |
|
| 115:05 | . These are styrofoam mothballs, the of thing you put in your closet |
|
| 115:09 | keep the mosque for meeting your right? He thought the spherical mothballs |
|
| 115:15 | things like spherical fluids in the rock . Right? And so he put |
|
| 115:19 | in a box, he impregnated with clear epoxy resin. He made the |
|
| 115:23 | cross sectional view to show how spherical tacked together spheres. Only touch at |
|
| 115:30 | points. All right, so you expect to see a lot of spheres |
|
| 115:37 | any random cross sectional view. Okay this example here, this is the |
|
| 115:42 | cornflakes. He took cornflakes because he that would represent some of the play |
|
| 115:48 | . Right? And this is the they packed together. Right? |
|
| 115:53 | Remember this is all before compaction because describing what the de positional texture |
|
| 116:00 | You have to back out any compaction . All right. And then little |
|
| 116:04 | pods, little solitary corals that live shallow water. And then here here |
|
| 116:10 | mollusc and the red algae. So this is why the system is |
|
| 116:16 | why the classification scheme is so challenging you you have to project back into |
|
| 116:23 | rock or have some understanding of how different geometries packed together. Alright. |
|
| 116:28 | is also where some of the sedimentary can help answer the question about whether |
|
| 116:34 | was any mud in the system or . Right. Trying to decide grant |
|
| 116:39 | versus much support. All right. let's just go through some examples |
|
| 116:43 | And this first example is a part a map, a bull reef body |
|
| 116:47 | a quarry in south florida and the keys. Uh The reef goes for |
|
| 116:51 | of meters laterally. It's just wall wall coral lined up in growth position |
|
| 116:56 | this. So we never done them encounter a coral and growth position. |
|
| 117:01 | would have signed that to the bounce . Okay, but notice the bounce |
|
| 117:06 | . It's not just coral. There's or proxy filled with sediment between |
|
| 117:11 | which is potentially part of the So here it's a skeletal, what |
|
| 117:17 | call the caracal grain stone yesterday? So you want to you want to |
|
| 117:22 | just call this a coral bound but you want to say coral brownstone |
|
| 117:26 | a caracal Greenstone matrix. Right? the Greenstone is also contributing potential reservoir |
|
| 117:33 | . All right. Second example uh east texas, Jurassic, the |
|
| 117:40 | and political fabric. I've not introduced yet to all the fabrics in these |
|
| 117:45 | . But the white crystals did you here are calcite cement? These are |
|
| 117:50 | die genetic cements. Okay, the is our porosity. All right. |
|
| 117:56 | all almost all between the grains. ? So, that's primary process to |
|
| 118:00 | with. You see the wood Right? And then you see some |
|
| 118:06 | would be called P Lloyd's. Because there may critized ovoid shape. |
|
| 118:11 | right. And then anybody remember what were from yesterday? The grains are |
|
| 118:21 | into each other. What causes Mhm, pressure solution? Right. |
|
| 118:27 | grain two grains suturing. That's a of pressure dissolution. That's what happens |
|
| 118:33 | grain stones. You can get style cut this, but you also get |
|
| 118:37 | degree in psychiatry. Okay, So has obviously created over compacted framework |
|
| 118:44 | And what has done I'm asking you do backtrack that effect out. |
|
| 118:49 | because you're trying to describe the oppositional . So what's missing here. What |
|
| 118:56 | you see between these grains? That's open pore space or poor filling |
|
| 119:01 | No Mick. Right, Okay. if you can look at the |
|
| 119:06 | it would be like that cora showed the last lecture that had the cross |
|
| 119:10 | . Remember that Greenstone with a cross ? So that would tell you right |
|
| 119:15 | the bat. This was a high Greenstone. There was never any |
|
| 119:19 | Right in the system. Right? even backing out the compaction, this |
|
| 119:24 | to be great supported fabric with no . Right? So grain stone. |
|
| 119:29 | . So this would be a political grain stone. And this is an |
|
| 119:34 | reservoir in the subsurface. Okay, because supports work, nope nothing was |
|
| 119:47 | nothing was bound? The only time are bound is by santa bacteria to |
|
| 119:52 | stromatolites or parts of reefs for the for strom's dinner grow. That's |
|
| 120:01 | Okay. Everything else we consider to not bound organically at the time of |
|
| 120:07 | . Okay. Yeah, they can cemented. That's a different process. |
|
| 120:14 | die genesis not deposition. All Actually should see all of us. |
|
| 120:23 | . What personally cemented? That's marine . That's die genetic. Okay. |
|
| 120:38 | . It's not organically bound. The grounds are not created by organic |
|
| 120:43 | They're created by marine sedimentation. That's type of guy genesis. And that's |
|
| 120:48 | next lecture. I'm gonna take you all those diabetic effects. So you |
|
| 120:52 | that. Okay. Um All right let's go another example here. |
|
| 121:02 | And what are these grains again, remember the micro structure. Radio good |
|
| 121:12 | micro structure. Right. And then is this? That's the Mc. |
|
| 121:19 | , okay. Said I don't I just say Mick. Right. |
|
| 121:27 | people migrate. The british were What? It's always been Mick. |
|
| 121:39 | to me. Okay, but that doesn't really matter. The point is |
|
| 121:43 | is such a fine grain material that can't resolve the individual components. That |
|
| 121:46 | our definition of a critic matrix. , now you're going to learn in |
|
| 121:51 | next lecture that sometimes what happens to , right, Because of its fine |
|
| 121:56 | , it's more reactive dye genetically. , Right. Find stuff is always |
|
| 122:02 | reactive than bigger stuff in terms of reaction. And so sometimes Mick |
|
| 122:09 | will do what it will re crystallize will dissolve on a fine scale and |
|
| 122:13 | precipitate these courses. Sparring cal So here the cal sites are not |
|
| 122:18 | poor filling cement, they're not growing open pore space, they're replacing the |
|
| 122:23 | fabric. Okay. And you can how it actually cuts into part of |
|
| 122:28 | new it. Right, So it part of the you that's the evidence |
|
| 122:31 | this is di genetic fabric. And course the black crystals are pyrite and |
|
| 122:36 | later die genetic as well. so again, we're trying to describe |
|
| 122:41 | of fabric. So we have to the sperry calcite as if it was |
|
| 122:46 | . Right to begin with. so we have lots of grains and |
|
| 122:52 | have Mick? Right, so this be a grain stone. The |
|
| 122:57 | So the question is is it Pakistan Pakistan? Remember Dunham's mothballs, they |
|
| 123:05 | touch at four points. Okay, you don't expect a lot of who |
|
| 123:08 | to be touching it at any random of you. All right there, |
|
| 123:12 | outside that plane of view. So would actually suggest that most of this |
|
| 123:18 | grain support based on the way spherical packed together and uh this Mick |
|
| 123:25 | is either mud that's filled in. , I'm gonna show you to complicate |
|
| 123:32 | in our next lecture, I'm going show you that you can have a |
|
| 123:35 | marine cement. All right, in grain stone. Now you would never |
|
| 123:41 | that from this view, but if was marine cement then this would be |
|
| 123:44 | grain stone marine cemented, right? you could prove that, but you |
|
| 123:49 | know that here, so that I the way to describe this is to |
|
| 123:52 | this a politic pack stone, And I would call it an |
|
| 123:56 | high mud pack stone because most of pore spaces filled in in fact, |
|
| 124:02 | the pore spaces filled in with nick , okay, the patient decisions that |
|
| 124:12 | , yeah, well it kills the and permeability. They both do. |
|
| 124:20 | both do, but it has implications your environmental setting, right? And |
|
| 124:24 | you map the sand body out, ? You've got to give me time |
|
| 124:29 | develop the story here, I can't everything in one lecture, So, |
|
| 124:33 | you're going to see when we talk you a sand bodies. There are |
|
| 124:35 | parts of sand body system. There's active part that's actively agitated every day |
|
| 124:42 | wind wave or tidal current agitation. where you make the good well, |
|
| 124:47 | of do a grain stones and then have a stabilized flank where some of |
|
| 124:52 | get shut off in a deeper water get add mixed with mud. And |
|
| 124:57 | may be what this is. assuming that's de positional Mick, |
|
| 125:02 | And not a marine cement. But this is a marine cement, then |
|
| 125:07 | will be part of the act of where you develop some hard grounds on |
|
| 125:11 | surface of the so we're trying to little bits and pieces of evidence in |
|
| 125:19 | rock that that better help us refine de positional setting. We're sort of |
|
| 125:25 | Sherlock Holmes. I mean, that's what we're trying to do here is |
|
| 125:29 | for a little little bits and pieces evidence that help us understand what's going |
|
| 125:36 | . Yeah, let me let me you off because I'll address all that |
|
| 125:40 | our next lecture. Okay, um , so I'll call this a |
|
| 125:49 | I'm sorry, new politic Pakistan. , my Pakistan. All right. |
|
| 125:53 | then a couple examples here mormon critic and then here the p Lloyd's |
|
| 125:59 | mostly p lloyds are probably fecal pellets these are by attributed sequences. |
|
| 126:06 | Uh yeah, possibly a calc sphere here, but And then here's some |
|
| 126:14 | them. A critic fabric has been crystallized again. The sparring calcite. |
|
| 126:18 | these are P. Lloyd's, These are definitely sand sized P. |
|
| 126:23 | is with them. A critic A lot of these are closely spaced |
|
| 126:26 | not future together. So this is a Pakistan and political Pakistan. And |
|
| 126:33 | that with this sample same age But you see fewer P Lloyd's. |
|
| 126:41 | see vague political fabric. Few little grains here. There's a nice little |
|
| 126:47 | system calc sphere. Hear a lot . My critics the grains are more |
|
| 126:53 | spaced. Right? I think here have to conclude this more. Much |
|
| 126:59 | . All right. So that means going to be a wacky stone or |
|
| 127:03 | stone. So what was the way just differentiate? Blackistone had more than |
|
| 127:11 | of these larger grains. Okay. , I think if you you |
|
| 127:15 | everybody judges this differently. But I The P. Lloyd's a skull material |
|
| 127:20 | up more than 10% of that So that would make a wacky |
|
| 127:24 | Okay, so skeletal political wacky stone you could say mollusc alsa sphere. |
|
| 127:31 | , we Pakistan however, you want do it. Okay, but Pakistan |
|
| 127:37 | . And then maybe something like I would call more of a lime |
|
| 127:41 | stone. You can see a few here outline of a calc sphere. |
|
| 127:46 | MMA critic fabric again, partially re again. If you think it's less |
|
| 127:51 | 10% grains, then this would be out a line mud stone. |
|
| 127:58 | All right. Now that's the limestone . Now, what complicates everything in |
|
| 128:03 | is the other die genic over print could come into play and that is |
|
| 128:08 | ization. Right? Lime stones can replaced by dolomite and sometimes decolonization completely |
|
| 128:16 | the fabric. Right? You don't any grains or texture. But sometimes |
|
| 128:22 | you see here, it perfectly preserves deposition of fabric. Okay. And |
|
| 128:29 | do I know this is don't replaced dolomite. You can't tell looking at |
|
| 128:34 | thin section. Alright, so we staining techniques that we use where we |
|
| 128:41 | in the thin section with these organic and they help differentiate between calcite and |
|
| 128:47 | calcite material. Okay, so dolomite stain courts wouldn't stain and hydro I |
|
| 128:54 | stain and then we tell anhydride and from carbonate by their by refrigerants or |
|
| 129:00 | clear beach and things like that. , so I tried to stay in |
|
| 129:04 | thin section with what's called a lizard red. S. This is a |
|
| 129:08 | staying for detecting cal side if this cal acidic. Everything would turn |
|
| 129:14 | All right. Or pinkish color reddish color. So the grains have been |
|
| 129:18 | by dolomite. The Mc. Been replaced by dolomite. Okay, |
|
| 129:24 | how do we incorporate that into our scheme? Because you darn well want |
|
| 129:29 | to know that that's a Dulles Right. And now the limestone because |
|
| 129:34 | know Dulles stones fracture even better than limestone naturally. And they would respond |
|
| 129:41 | way hydraulic to hydraulic fracturing. so ah you can treat this like |
|
| 129:48 | regular denim classification scheme and say Dramatized, needs completely replaced by |
|
| 129:58 | Okay, so P Lloyd's a few . A few uh inter classed. |
|
| 130:05 | would call and then you get him critic matrix. I would call this |
|
| 130:08 | a political Pakistan before decolonization. And you can say dull monetized political |
|
| 130:17 | Okay, the other way now in literature is to use the term Dolo |
|
| 130:25 | . Political Dolo Pakistan. Okay. Pakistan means completely replaced by dolomite. |
|
| 130:33 | , now, what if it was dull monetized, personally replaced by |
|
| 130:38 | You'd say Dola medic. And you tell people how much dolomite, |
|
| 130:45 | whatever it is. Okay, everybody about that. Oh, the only |
|
| 130:55 | , quick way to tell is to the outcrop Iraq or disdain the thin |
|
| 131:02 | . Now you could you could powder up into a powder sample and put |
|
| 131:06 | the X ray diffraction and prove that . But that's yeah, that destroys |
|
| 131:12 | fabric and time intensive. Right? I haven't done this yet, but |
|
| 131:17 | I'll do is I'll send you ah little summary of our techniques we use |
|
| 131:23 | carbonates. Okay. And that includes staining techniques includes a different geochemical techniques |
|
| 131:29 | used to evaluate the digestive carbonates. I'll post that on blackboard. |
|
| 131:37 | so I'll do that sometime this You're going to see lots of examples |
|
| 131:44 | I where I have stains. And this is sort of your first introduction |
|
| 131:49 | the staining technique. All right. , sometimes you're carbonates look like |
|
| 131:54 | right? Everything completely destroyed by You got porosity. The black material |
|
| 132:01 | a pyro. Bitumen thermally altered dead . The white is diagnostic and |
|
| 132:07 | but when you look at the dolomite this is taken with the white paper |
|
| 132:10 | . I shot this with the piece white paper hoping to see rally grains |
|
| 132:15 | other samples. It works beautifully. could see the rally grain fabric |
|
| 132:19 | It didn't work. Okay, So do you do? Well, you |
|
| 132:22 | physically described the rock and so, know, this is a medium crystalline |
|
| 132:28 | dollar stone and I would modify I would say uh the tu minus |
|
| 132:35 | hydrate IQ medium crystalline Dulles Stone with buggy porosity. Alright. Doesn't tell |
|
| 132:46 | about the deposition of setting. But least it tells people what kind of |
|
| 132:49 | you're dealing with. Right? And the reservoir quality is. So sometimes |
|
| 132:54 | life. Right? And you just do anything else with that rock. |
|
| 132:59 | right, finish up here. Um am gonna introduce you to a another |
|
| 133:06 | scheme that came into play By two geologists about 10 years after Dunham published |
|
| 133:12 | scheme, uh Aston Embry and Ed , we're working devonian outcrops in Northwestern |
|
| 133:21 | of Western Canada. And they were these strong top word, reefs and |
|
| 133:27 | have a lot of course green debris with them. And they just found |
|
| 133:31 | classification scheme inadequate for describing some of coarser grain fabric. Okay. And |
|
| 133:39 | so they decided to add some new here for both the institute part of |
|
| 133:44 | reef, what Donna would call abound . They broke it into three terms |
|
| 133:48 | reflect the process that creates the refilled . And they added two new terms |
|
| 133:55 | characterize the course of debris. so this is a classification scheme that's |
|
| 134:02 | for reef related deposits. Okay. it's now being applied to any coarse |
|
| 134:09 | limestone, including things like good Alright, that's not the intent. |
|
| 134:16 | . But basically what they did was recognized two types of refill lime |
|
| 134:21 | A lot venus would be the Right? And a talk venus would |
|
| 134:26 | the institute part of the restructure. a locked in this reef limestone material |
|
| 134:33 | not be bound organically. They added terms for coarser grain fabric And what's |
|
| 134:39 | coarser grain cut off two, which not very much right. I |
|
| 134:44 | that's 2 mm of course, I you a picture yesterday, the re |
|
| 134:49 | in Australia. Remember those big kabul pieces. So that's more typical of |
|
| 134:54 | debris, but they use just Situation he had greater than 10 of greater |
|
| 135:02 | two millimeter sized material alright of reef . If if it was that And |
|
| 135:09 | grains as big grains were touching, call that a rude stone. And |
|
| 135:14 | the bigger pieces we're not touching and supported by material Less than two in |
|
| 135:20 | , they called it a floats Okay, so matrix does not mean |
|
| 135:27 | . Okay, In this classification Matrix means material less than two in |
|
| 135:34 | . Okay, so route stone Could big chunks of coral with open four |
|
| 135:42 | or it could be big chunks of touching each other with a grain stone |
|
| 135:46 | pack stone or wacky stone fill depending where this debris gets shed. |
|
| 135:52 | and the same with the float Right? You could have a coral |
|
| 135:55 | stone in a Greenstone matrix or Pakistan or Pakistan matrix, depending on where |
|
| 136:01 | big pieces get shed. Okay, if you work grateful plays, you'll |
|
| 136:07 | people use this terminology for the course great material, fine grain stuff. |
|
| 136:12 | just use the regular done on classification and then the attack industry for lime |
|
| 136:19 | done, it would have called everything see here abound stone and you can |
|
| 136:23 | do that. Right? Brownstone is not trying to downplay the term |
|
| 136:27 | I'm just trying to tell you that now are switching to this kind of |
|
| 136:33 | . So frame stone for a situation you can demonstrate the corals are in |
|
| 136:38 | and are growing to create a rigid . Okay, bind stone as you'll |
|
| 136:43 | next weekend. Parts of the the reef flat actually get bound over |
|
| 136:48 | by read out your corals. That's strong catalytic fabric. That's what we |
|
| 136:54 | a coral or red algal bind Okay. That contributes to part of |
|
| 137:00 | reef. And then baffle stone would to these other settings that are quiet |
|
| 137:07 | , whether it's shallow or deep where don't create a rigid structure, they |
|
| 137:13 | up, right? And they trap , right to create a build |
|
| 137:17 | but it's not a high energy build . Okay, so they call that |
|
| 137:20 | baffle stone because they say the So this could be coral stream atop |
|
| 137:26 | seagrass. This could be uh, noise and bright zones growing and not |
|
| 137:33 | a rigid framework but trapping Mick. . The term would be baffled stone |
|
| 137:38 | that. Okay, so here's Here's the summary, right? The |
|
| 137:43 | examples of institute reef for a talk from limestone, the course of |
|
| 137:50 | more than 10% of greater than two sized fragments route stone float stone. |
|
| 137:57 | , so you'll you'll be using this as we go along and and talk |
|
| 138:02 | reef systems and build ups and things that. Okay, any questions about |
|
| 138:08 | this? You want to take a quick stretch break here and then I'll |
|
| 138:15 | set up and we'll get into the of die genesis for the rest of |
|
| 138:20 | . All right, so let's let's uh, let's evolve into the |
|
| 138:30 | of carbonate diet genesis to make sense of some of these other fabrics that |
|
| 138:36 | been looking at. Right? The solution fabrics, the cement fabrics, |
|
| 138:42 | secondary poor types try to put this some sort of context here and so |
|
| 138:48 | need to make a few introductory comments . And first is we need to |
|
| 138:54 | think about what's happening to ferocity during genesis because die genesis probably reflects the |
|
| 139:01 | history of these rocks. What's happening the porosity. And so we need |
|
| 139:05 | first ask, well, what is is our starting ferocity? What do |
|
| 139:09 | start with on the sea floor? show you that in a minute. |
|
| 139:12 | what controls the starting ferocity and by , permeability. Well, always, |
|
| 139:19 | first controlled by the deposition all faces . The texture associated with that environment |
|
| 139:24 | your starting porosity and permeability. And later die genesis, which can start |
|
| 139:29 | the sea floor and continue with Always obviously determined your final reservoir equality |
|
| 139:37 | you and trap any hydrocarbon as your in looking for oil and gas |
|
| 139:43 | Okay, so the term dia genesis these chemical changes the sediments of rocks |
|
| 139:51 | with progressive burial and the complexity of to predict ferocity. Head of the |
|
| 139:57 | bit and trust me industry has been to do this forever. They were |
|
| 140:03 | to do this before I started in business. Um and it's very difficult |
|
| 140:07 | do both in carbonates and plastics because of these bigger scale controls the deposition |
|
| 140:13 | faces and the dye genesis are in controlled by other factors. So, |
|
| 140:18 | are the factors we're going to talk next week when I take you through |
|
| 140:21 | environments and the basis of the deposition . So, I'll come back to |
|
| 140:27 | next weekend. But for today, need to talk about these other key |
|
| 140:32 | , right, The geological age? is that important? Because it determines |
|
| 140:36 | the players were? It also determines they're starting. The neurology was |
|
| 140:41 | We saw how the mineralogy the grains change geologically. Alright. The texture |
|
| 140:47 | obviously important because texture controls the permeability the flow through of water to dr |
|
| 140:54 | genesis and part of that flow through water early is due to climate. |
|
| 141:00 | , we want to pay attention to . And we used to be more |
|
| 141:03 | about climate. From the standpoint of we in a rainy climate or in |
|
| 141:08 | dry area evaporated climate. The climate includes the trade wind systems that I |
|
| 141:13 | about yesterday and the trade winds can be a driver for marine sedimentation as |
|
| 141:19 | . So it ties into some other of marine sedimentation. Then, of |
|
| 141:25 | , the two critical drivers for ultimate uh response are burial history and the |
|
| 141:32 | fluid chemistry that comes along with progressive . The interplay of these two factors |
|
| 141:38 | what we call di genetic environments. for limestone. Dia genesis. We |
|
| 141:43 | these three simple digest environments marine at surface, fresh water at the surface |
|
| 141:50 | then so called deep burial where we into the realm of pressure solution. |
|
| 141:55 | then I listed tectonic activity here. I started this business. We just |
|
| 142:01 | about faults from the standpoint of and hydrocarbons. Right to help create side |
|
| 142:08 | or create topography for deposition on the floor. But now we recognize that |
|
| 142:15 | deep seated, reactivated basement faults are conduits for hot fluids coming out of |
|
| 142:22 | . And that can be an important for later burial die genesis and ferocity |
|
| 142:28 | . And then what's unique about carbonates to classic says there's a strong interplay |
|
| 142:34 | what happens early diet genetically. What late. So you really want to |
|
| 142:39 | the digest history in order to understand , why you've got prostate preserved or |
|
| 142:44 | preserved that ferocity. Okay, so start this discussion, we need to |
|
| 142:50 | about what's our starting for austin permeability to do that. We'll go to |
|
| 142:55 | diagram like this, which is uh on institute field measurements in the caribbean |
|
| 143:02 | south florida and these shallow marine carbonate . They analyzed uh, grain stones |
|
| 143:10 | terms of their prostate perm all the up into the title, flat wacky |
|
| 143:15 | . All right. There's no lime stones here because I said they're |
|
| 143:18 | You don't find them in most selling carbonate successions. So this is a |
|
| 143:23 | of percent ferocity versus de positional The black dot and the yellow bars |
|
| 143:28 | essentially the average porosity for each The average permeability is listed under the |
|
| 143:35 | bar and then the range of permeability that they encountered are in parentheses. |
|
| 143:41 | , so look at these numbers. mean, actually that's interesting. The |
|
| 143:45 | stones and pack stones have overall lower ease than the mormon critic wacky |
|
| 143:53 | The Pakistan start off with 70, on the sea floor, but within |
|
| 143:58 | few tens of feet of burial, will quickly de water. 2 50 |
|
| 144:02 | porosity units. Okay. But when they're right at the surface, |
|
| 144:08 | can see the high values. All . And look at the perms. |
|
| 144:13 | right. Where the better permit abilities always associated with the grain stones are |
|
| 144:18 | mode Pakistan's for the obvious reasons the throats are much wider. So good |
|
| 144:24 | . And what kind of ferocity is ? It's mostly micro porosity. |
|
| 144:29 | you know, that means you're gonna lower permeability and this is more typical |
|
| 144:33 | the starting numbers. Don't be misled this high number here. What do |
|
| 144:38 | get on tidal flats to give you zones of high permeability would be things |
|
| 144:44 | mud cracks and uh finessed real ferocity we talked about before. All |
|
| 144:50 | But you know, the the average overall matrix permeability is usually much |
|
| 144:56 | Like you see for these numbers Okay, so we need to keep |
|
| 145:00 | in mind. Right? This is starting point before die genesis, |
|
| 145:05 | And again, if you took this of context, you say, |
|
| 145:08 | jeez all these carbonates, you have great reservoir potential and you know |
|
| 145:15 | what do we chase? We didn't these metacritic carbonates. We chase these |
|
| 145:19 | of deposits because they had the better and they were able to hold on |
|
| 145:24 | the permeability longer during burial in order entrap the hydrocarbons. Right. And |
|
| 145:30 | used to look at these mormon critic as being a top seal. Four |
|
| 145:34 | seal to those gravestones are blowing my Okay, again, this is just |
|
| 145:41 | a limestone standpoint, right? And decolonization, but let's put some context |
|
| 145:47 | this. All right. Here's the prostate versus frequency. Here's the values |
|
| 145:55 | I just showed on the previous diagram out for the modern About 35% porosity |
|
| 146:01 | some of the grain stones all the up to 80%. Where is that |
|
| 146:08 | comes from? It comes from the in deep water. So the precursors |
|
| 146:12 | these chalk deposits start off at 80 on the sea floor. Okay. |
|
| 146:20 | then the real world is post ancient shown in red End up with less |
|
| 146:25 | 5% porosity. Okay, so what happened with time with burial with di |
|
| 146:33 | ? What's the tendency? The tendency to take that high porosity and destroy |
|
| 146:39 | destroyed by di genetic processes leading to imitation. Right? Where the cements |
|
| 146:45 | that ferocity. All right. And reservoirs Shown here 5% porosity. You |
|
| 146:53 | , this is an old diagram. should be extended now because some of |
|
| 146:57 | over pressured North Sea chalk reservoirs have porosity right now. Okay. That |
|
| 147:05 | reservoirs represent what they represent the exception that trend. Right of parasite progressive |
|
| 147:13 | of proxy with burial. Somehow, either inhibited the loss of ferocity long |
|
| 147:19 | to entrap the hydrocarbon make a reservoir we created ferocity after the rocks have |
|
| 147:25 | buried. Okay, so let me you some context to this diagram. |
|
| 147:30 | been teaching off this diagram forever. up until the late 80s, early |
|
| 147:35 | , I used to explain this trend by saying reservoirs exist because we inhibit |
|
| 147:41 | detrimental effects of die genesis to preserve and attract the hydrocarbons. Alright, |
|
| 147:48 | then what happened in late 80s, 90s, we started to document |
|
| 147:53 | Secondary porosity development. That means after rock story been deeply buried. The |
|
| 147:59 | kind of fluid came through to create porosity. So now some of these |
|
| 148:05 | exist because of favorable die genesis. , so die genesis can be |
|
| 148:13 | Right, destroyed, processing perm or can be favorable and create porosity and |
|
| 148:18 | . And that's the challenge. Trying figure it out. Right. Are |
|
| 148:21 | creating or forming and creating secondary prostate and trying to hold on to it |
|
| 148:30 | are we creating it closer to the of hydrocarbon penetration of migration. That's |
|
| 148:35 | the choices. All right. And the goal here for the rest of |
|
| 148:40 | day is to is to give you feel for the different digest environments and |
|
| 148:45 | you how we try to figure that , right? We try to figure |
|
| 148:47 | the digest history where the fluids are from. And if you can do |
|
| 148:52 | , I think you can exploit some these relationships in the subsurface. |
|
| 148:57 | so let's see how far we get launch. We got about 35 |
|
| 149:02 | We should get through the first part on marines imitation. So let's start |
|
| 149:09 | with a couple of general comments And the major digestive processes are listed |
|
| 149:15 | . So segmentation, what does that ? It means precipitation of a phase |
|
| 149:19 | calcium carbonate into a poor system dissolution removal of calcium carbonate. So people |
|
| 149:27 | the term leaching the same way. either way dissolution or leaching, you're |
|
| 149:33 | to see that these two are linked . When you dissolve calcium carbonate, |
|
| 149:39 | can go back into solution, it re saturate and it can re precipitate |
|
| 149:43 | a cement somewhere else. Okay, some of my colleagues call this donor |
|
| 149:49 | die genesis take from part of the by dissolution. But then put some |
|
| 149:54 | that back in as a poor filling . You're basically doing what rearranging the |
|
| 150:00 | and permeability relationships. Okay. That's the norm for a lot of these |
|
| 150:07 | scenarios. Okay. And then I've you briefly this term re crystallization. |
|
| 150:12 | another damn buzzword. The carbonate communities up with, you know, need |
|
| 150:17 | remember Nia morph is um but it's all it means is it's more of |
|
| 150:21 | multiple replacement of one mineral by another Or one texture by another texture. |
|
| 150:28 | when we go from a reaganite we've taken originated coral and we replace |
|
| 150:36 | by calcite without destroying the coral That's re crystallization. Okay. Or |
|
| 150:42 | I showed you from that Venezuela we take that Mick. Right. |
|
| 150:46 | we change it into a coarser sparred cal side. That's re crystallization. |
|
| 150:52 | doing things on a multiple basis. , we're not creating secondary porosity. |
|
| 150:57 | then back selling it was course Okay. To see the implications. |
|
| 151:02 | crystallization does mostly mostly buggers up the of texture. Like you saw for |
|
| 151:08 | Venezuelan example. Right. Yeah. some of the Mc. Right? |
|
| 151:13 | mass some of the grains. so it usually doesn't play much of |
|
| 151:17 | role in reservoir quality. So and same thing. Yeah, it's |
|
| 151:25 | somebody has to come up with some term. Right? This is how |
|
| 151:29 | make a name for themselves in Right? One term. Just Uh |
|
| 151:36 | . That's it for some people it out to be that simple. All |
|
| 151:42 | . Yeah, it's a guy any don't want to offend any. Ag |
|
| 151:45 | here anybody go to texas A. M. Uh there's a carbonate guy |
|
| 151:50 | texas A. And M. It a former right student. He was |
|
| 151:54 | first he was the first grad rice with James Lee Wilson. I was |
|
| 151:58 | last and rice with James lee Wilson a famous carbon a guy his name |
|
| 152:05 | Waner became a professor of geology at and M. And he published a |
|
| 152:10 | on the ramp. And forever the model and forever became known for the |
|
| 152:16 | . All right. Made his name that one paper. I mean, |
|
| 152:20 | published on other stuff. Not wayne a very nice guy. Was not |
|
| 152:24 | to to denigrate him in any but but sometimes it's a simple concept |
|
| 152:29 | that. That makes the name, ? And then there's pressure solution, |
|
| 152:35 | ? And this is carbonate dissolution under . Right? He has nothing to |
|
| 152:40 | with heat. It's pressure. All , pressure dissolution the last crisis style |
|
| 152:46 | the grain to grain Sutra. And showed you before you're going to see |
|
| 152:50 | that links back to the segmentation So pressure solution and cal sites, |
|
| 152:56 | are another donor receptor dia genesis Okay. And then dole immunization will |
|
| 153:04 | as a separate topic uh later this . Okay. So I need briefly |
|
| 153:11 | talk about a couple of drivers for dia genesis. And I'm going to |
|
| 153:16 | this sound really simple. If it so simple we would be able to |
|
| 153:21 | ferocity head of the drill bit and been able to do that. But |
|
| 153:25 | there are two key controls to drive die genesis in lime stones. And |
|
| 153:30 | first is the geochemistry of the poor . Right. This is chemistry went |
|
| 153:36 | . You're all familiar with the famous equation that shows calcium carbonate plus carbonic |
|
| 153:43 | in equilibrium with calcium cat irons and and ions. At the same time |
|
| 153:49 | acid in equilibrium with water And 0. 2. Okay. At |
|
| 153:56 | . Nothing happens die genetically. So you die genesis as a dis equilibrium |
|
| 154:02 | . So the question is how do create disequilibrium in this for this chemical |
|
| 154:08 | ? You do it by either changing temperature or changing the pressure. |
|
| 154:14 | Because this influence is what it influences ph of the poor fluid. Because |
|
| 154:21 | either removing or adding carbon dioxide to fluid. Okay. So this is |
|
| 154:27 | critical control the input or output of . two. And that's controlled by |
|
| 154:32 | and by by pressure. Okay so higher temperatures what happens at higher temperature |
|
| 154:40 | carbonate soluble itty decreases Because co two ability is also decreasing. What that |
|
| 154:46 | is you are the higher temperature. are doing what you're bleeding out The |
|
| 154:54 | two right? You're taking that fluid you're losing the co two. The |
|
| 154:58 | comes out of that fluid at higher . And when you drive the gas |
|
| 155:02 | and you shift the reaction to the right, you create disequilibrium. |
|
| 155:08 | what does that favor favors precipitation, you're poor food is saturated or supersaturated |
|
| 155:15 | with calcium carbonate. Okay, if you have CO two in the |
|
| 155:21 | and higher pressure, what is that do Pressure pushes the co two into |
|
| 155:28 | fluid creates disequilibrium. Makes carbonic acid favors dissolution. So at higher |
|
| 155:35 | That's where we tend to see carbonate . All right, well, let's |
|
| 155:42 | about this, right? Um On one hand, you know, we |
|
| 155:48 | a we take a a limestone and start to bury it. What happens |
|
| 155:54 | temperature? What happens to pressure? right, they're both going up. |
|
| 156:01 | on the one hand, I'm telling what we're getting precipitation because of higher |
|
| 156:06 | but we're getting dissolution because of higher seems counterintuitive. But it's not because |
|
| 156:12 | operate at the same time. The thing that kicks in is the pressure |
|
| 156:18 | and that's what causes the pressure That makes the style lights. That |
|
| 156:22 | the grain to grain citrine. He the carbonate material, then it goes |
|
| 156:26 | solution and locally re saturates and now precipitates at higher temperature as a poor |
|
| 156:34 | calcite cements? Okay so these two beautifully explain barrelled I genesis. |
|
| 156:43 | And then the last point here the eligibility increases with organic matter decay. |
|
| 156:50 | is where you favor dissolution. Where of this organic material starts to |
|
| 156:55 | You give off CO two, you us weak organic acids like carb oxalic |
|
| 157:02 | . You give up faith to These all our potential mechanisms to create |
|
| 157:08 | fluid that drives barrel dissolution. So is another way to create the solution |
|
| 157:13 | the subsurface without having to use Okay so that's why I want to |
|
| 157:20 | attention to what are nearby source rocks doing because sometimes when they start cracking |
|
| 157:26 | hydrocarbons right? They can start cracking these weak organic acids or they can |
|
| 157:30 | off CO. Two or H. . S. And that can be |
|
| 157:33 | fluid. The gas that creates the fluid. Right? Co. Two |
|
| 157:39 | water makes carbonic acid which I just you here. H. Two |
|
| 157:42 | Makes sulfuric acid. Right? With and sulfuric acid. Does what dissolves |
|
| 157:53 | still casing in the wellbore? That's the problem with the high |
|
| 157:56 | two s. Reservoir is they have replace the steel casing every few |
|
| 158:02 | Right? So that's the key And then the other key control is |
|
| 158:07 | starting meteorology obviously I showed you this yesterday to introduce you to the |
|
| 158:13 | Why do we care about this? if you look at the civility |
|
| 158:19 | what happens when you take your Dragon and heimat calcified material out of marine |
|
| 158:26 | ? You expose it to fresh water you buried to higher temperature and |
|
| 158:30 | These sediments are going to want to stabilised to lome calcite fabric. |
|
| 158:36 | Or they could go to dolomite if have a way to add more magnesium |
|
| 158:40 | the system. Alright but usually in rock record it goes to lome |
|
| 158:44 | That's why in the rock record, you get past the middle part of |
|
| 158:48 | place is seen, everything is converted lome calcite. All the lime stones |
|
| 158:52 | lome calcite. Okay so the question how do you do that? Well |
|
| 158:57 | reaganite wants to do what first it to dissolve regularly grains dissolve first to |
|
| 159:03 | secondary multi ferocity. But then what to that dissolved carbonate goes back into |
|
| 159:09 | . Re saturates and re precipitates as nearby poor filling calcite cement. Lomax |
|
| 159:16 | . Okay, donor receptor dia genesis there's a volume change here. If |
|
| 159:23 | remember the difference in the volume. this was you know from the log |
|
| 159:29 | logs 2.72 specific gravity 2.9 five for reaganite theoretically, what that means is |
|
| 159:37 | you go from a reaganite to Lomax , You're creating an excess of almost |
|
| 159:43 | calcium carbonate in a closed system, would do that? Okay so the |
|
| 159:48 | is could that add more cement than you would think. Okay, so |
|
| 159:54 | to think about and then a rag I can also re crystallizes. I |
|
| 159:58 | talked about remember the Reagan I coral to cal Siddiq mineralogy without destroying the |
|
| 160:03 | fabric. There still has to be volume change there. But there's no |
|
| 160:08 | secondary porosity development. And then high al side likes to go to low |
|
| 160:13 | calcite. Just by kicking out the . There's no dissolution involved. You |
|
| 160:18 | lower the magnesium. You go you know, anywhere from 10 12% |
|
| 160:23 | too. 38% magnesium and some of red algae. And take it down |
|
| 160:28 | low mag calcite which is we defined being less than one. Less than |
|
| 160:33 | percent magnesium. All right. That's normal transformation. That's why in the |
|
| 160:39 | record all these former high made calcite like red algae, benthic, |
|
| 160:44 | A kind of germs are all very preserved. They're not dissolved out because |
|
| 160:49 | were just heimat calcite. They just the magnesium, but sometimes they do |
|
| 160:55 | dissolved out. And if you see that's a red flag that tells you |
|
| 160:59 | something really unique about the fluid chemistry was acidic enough to dissolve even the |
|
| 161:05 | mag. And in some cases even mag cal side. And these |
|
| 161:09 | Okay. Yeah. All right. let me put everything into the context |
|
| 161:20 | these diabetic environments. All right. said to our near surface and so |
|
| 161:27 | burial. And then what support fluid for the marine traumatic normal seawater. |
|
| 161:34 | right. And what does the term mean? That just means the poor |
|
| 161:37 | completely saturated with normal seawater. so let's take a look at that |
|
| 161:43 | genetic environment first. And before I into the processes and products. I |
|
| 161:49 | to talk about again, the main processes and products for I get into |
|
| 161:56 | of the controls that would be mechanization . Remember that process we talked about |
|
| 162:02 | , grain sits on the sea floor micro board and then in filled with |
|
| 162:06 | democratic cement. So segmentation is the part of the story. And as |
|
| 162:11 | said yesterday, if we're dealing with deep water basins, we would have |
|
| 162:14 | solution related to calcite or reaganite compensation . We're going to ignore that for |
|
| 162:22 | discussion. All right. So just let me remind you the common |
|
| 162:27 | of grains to get my critized if only partially my critized where you develop |
|
| 162:32 | Mc right envelope. This is the fate in the rock record. He |
|
| 162:36 | the Mc right envelope and either the within it or you fill that in |
|
| 162:42 | sparring cement Later on calcite cement. term spar just means equal dimensional cal |
|
| 162:49 | some out. Okay, so you've seen some pictures of this, but |
|
| 162:53 | is the common fate for a lot former Reagan knittig mollusk including rudest in |
|
| 163:00 | example they get broken down. They me critized on the outer part, |
|
| 163:06 | then the rest of it gets re . Remember how the fastest was on |
|
| 163:10 | sea floor nick, right envelope within few weeks or months, complete grain |
|
| 163:17 | within a few few years or Okay, so the main marine digestive |
|
| 163:27 | in shallow water is not the solution in these tropical subtropical settings are water |
|
| 163:33 | supersaturated with respect to calcium carbonate. if anything happens die genetically, it's |
|
| 163:40 | to be segmentation. Alright, so cement are either a reaganite or heimat |
|
| 163:47 | because these are the only two cement could precipitate in shallow marine waters. |
|
| 163:54 | , the good news is rarely do destroy all the processing on the sea |
|
| 163:58 | ? In fact, a little bit cement between these grains is a good |
|
| 164:01 | . And creating a rigid framework that later proxy lost by pressure solution. |
|
| 164:07 | , this is actually one of the historically we tried to preserve ferocity long |
|
| 164:12 | to entrap the hydrocarbons. All So what is the requirement for marine |
|
| 164:17 | ? You need persistent high energy but need periodic, stable stability on the |
|
| 164:23 | floor. All right, So I you it's being cemented together, but |
|
| 164:29 | would associate us with what rolling around day. Yeah, they can't be |
|
| 164:34 | together when they're rolling around so periodically have to find ways to stabilize them |
|
| 164:39 | enough to put a little bit of between those grains, Then you freeze |
|
| 164:43 | fabric that starts the incipient hard ground then you just keep adding more and |
|
| 164:48 | marines cement. It seems counterintuitive, I'll show you how we do this |
|
| 164:53 | weekend. Okay. When we talk modern wood, sand body environments. |
|
| 165:00 | . And so what does this all ? It means there are only certain |
|
| 165:03 | , all faces that are prone to sedimentation in shallow water, high energy |
|
| 165:10 | or parts of reefs, high energy stones, parts of those grain stone |
|
| 165:15 | . That's it. Anything that's quiet , low energy. Um, a |
|
| 165:19 | is not going to be subjected to imitation hard ground development. Okay, |
|
| 165:29 | before I show you the cement fabrics want to remind you of, we're |
|
| 165:34 | use three different attributes to characterize these kinds of cement between the different diabetic |
|
| 165:41 | . We're going to pay attention to morphology distribution by color. We |
|
| 165:47 | we mean, is that brownish in section, inclusion? Rich, |
|
| 165:52 | sort of a light brown color? is it clearer white conclusion free? |
|
| 165:59 | these white sparkle sites that you've been here in these thin sections. That |
|
| 166:03 | what we call clear, translucent. , what's the morphology fibers means |
|
| 166:09 | Like, Right. I need to bladed more of a stubby pointed crystal |
|
| 166:17 | this. And what's the common term this dog? To spar. |
|
| 166:22 | if you want to appreciate the Go look at your dog's teeth |
|
| 166:26 | All right. That's a dog to and then equal dimensional where the within |
|
| 166:31 | length are. About the same is I've been calling. Sorry, calcite |
|
| 166:35 | frequent equal dimensional shape. Okay. morphology. And then distribution ice epochs |
|
| 166:44 | it goes all the way around the except where the grains were touching. |
|
| 166:49 | means is confined to points of But the crystal shows curvature because of |
|
| 166:55 | capillary effect. I'll explain all this a minute and then equal dimensional |
|
| 167:00 | You have an open pore space. just fills in with a bunch of |
|
| 167:02 | frequent cal side crystals just creates this of sequin calcite segmentation. Okay, |
|
| 167:11 | let's start with the marine or agonized fabrics. All right, well we |
|
| 167:17 | this very well because we can go all these modern marine environments and |
|
| 167:22 | What's happening die genetically on the sea . We can look at the cement |
|
| 167:26 | . We understand the controls. Yeah. And then we're the goal |
|
| 167:30 | is to apply this to the rock . So we're gonna do this through |
|
| 167:34 | concept of what we call comparative sediment gleaning relationships in the modern trying to |
|
| 167:41 | back to the rock record. so a rag and I remember that |
|
| 167:47 | is a orthodontic mineral orthodontic minerals like make needle shaped crystals sometimes square |
|
| 167:56 | So don't be surprised to see square to these crystals. All right. |
|
| 168:00 | that's the morphology and then what's the color? The color typically is cloudy |
|
| 168:09 | there's a lot of credit in seawater gets incorporated into the crystal lattice that |
|
| 168:14 | that cloudier color. But the color the least reliable of the attributes for |
|
| 168:20 | these cements. And then what's the ? Well, it depends on the |
|
| 168:24 | of the ferocity if you're dealing with stones. So each one of these |
|
| 168:28 | represent a grain stone. What would see in a grain stone? You'd |
|
| 168:33 | isA pakis. Fibrous dragon knight. . That's the ice pack is fibrous |
|
| 168:41 | . That's typical ingrain stones because the system is not that big. |
|
| 168:45 | But if you get into a bigger system where you have bigger cavities where |
|
| 168:50 | crystals can grow and compete for What do you see happen you see |
|
| 168:55 | fibers organized into these fan shaped crystals this is called radio fibrous or fan |
|
| 169:03 | marine cements. Okay. And these big crystals because you've got room to |
|
| 169:08 | these bigger crystals. Okay, now can also precipitate the critic Iraq genetic |
|
| 169:16 | between the grains or in filling some the porosity. Should not be surprising |
|
| 169:23 | because I told you to make the right envelope. We did what we |
|
| 169:27 | the holes by micro boring and then filled it in with the critic marine |
|
| 169:32 | . And most of that is usually reaganite. Okay, so that's why |
|
| 169:35 | said Mick. Right. Is not deposition all. Sometimes it's diet |
|
| 169:39 | Alright, so let's look at some here. So this first examples from |
|
| 169:46 | me from the piece of modern from the police reefs in the western |
|
| 169:53 | Back in the 70s, they took Submersible down in front of the reef |
|
| 169:57 | 1000 ft in front of the They put dynamite charges into the reef |
|
| 170:01 | they blew out chunks of the Okay. You'll never be able to |
|
| 170:05 | that today. But they did it then. Okay. And so they |
|
| 170:09 | a bunch of chunks of reef and brought it up and this is one |
|
| 170:12 | the chunks that they brought up. this is the first discovery of this |
|
| 170:16 | cement. This is the first example even proved that we have marine sedimentation |
|
| 170:22 | in the oceans. Okay. Because , nobody knew that marine sedimentation existed |
|
| 170:28 | they made this discovery. Okay. you can see again, here's the |
|
| 170:33 | this is a reef cavity created within reef framework. Right? This is |
|
| 170:37 | of the bound stone. And look the cement. The first thing you |
|
| 170:41 | is the colours that light brown color cloudy. And then look at the |
|
| 170:46 | cement, they radiate from a single . So they're fibers crystals that organized |
|
| 170:51 | that radio fibrous or fan shaped morphology then they have an ice. A |
|
| 170:56 | distribution. They go all the way the cavity. Right. Because that |
|
| 171:01 | is saturated all the time with sea . Okay, So where is this |
|
| 171:07 | coming from? It's coming from sea , but it's not coming from one |
|
| 171:10 | of seawater. It probably takes thousands thousands of volumes of seawater passing through |
|
| 171:16 | reef to promote this cement. All . But what's the driver? You |
|
| 171:20 | a rigid framework? A wave oceanic breaks across it every seven or 10 |
|
| 171:25 | . Right. Forces water into that . Okay, and how quick is |
|
| 171:31 | process? Well, people have dated , not this example here, but |
|
| 171:35 | like this And they've shown growth rates 8-25 mm. 100 years. |
|
| 171:45 | That's pretty impressive. All right. the modern analog. This is what |
|
| 171:48 | see in a lot of modern Greece . Right. But only where do |
|
| 171:53 | see it? Just in the the proper? Right. The bounced on |
|
| 171:58 | of the reef for the upper Re slip. And that's it. Excuse |
|
| 172:04 | . Let's go back to the rock . Ancient analog. This is the |
|
| 172:08 | reef complex in west texas Bob Dunham in the 50 called all of this |
|
| 172:15 | , freshwater cave cement. Okay. published a paper on this. All |
|
| 172:22 | . And nobody could refute him because was no modern analog. But people |
|
| 172:26 | starting to doubt it because in some these outcrops, they would see these |
|
| 172:30 | girl like this. The fan shaped grow like this and then be encrusted |
|
| 172:35 | red algae and then the cement would on top of the red algae and |
|
| 172:39 | red algae. It's starting to look to people that this is not fresh |
|
| 172:44 | , but marine cement. All That nobody had an analog until the |
|
| 172:48 | example. Now look at what you in the permian, you see ice |
|
| 172:54 | pack his distribution to these cloudy You see the fan shape morphology just |
|
| 172:59 | I showed you in the modern. different now? This is not a |
|
| 173:04 | that's been converted to calcite by dia been re crystallized. But you still |
|
| 173:09 | some of the color. You certainly the morphology and you certainly preserve the |
|
| 173:15 | . Okay, so on that this has all been reinterpreted be marine |
|
| 173:21 | . Okay, this is compared to ology. Applying what we learn from |
|
| 173:26 | modern to the rock record. that's in cave systems. Uh, |
|
| 173:31 | reef systems with cavernous ferocity or bigger ferocity where you've got room to grow |
|
| 173:37 | big cements ingrain stones. You don't that space. Right. So what |
|
| 173:44 | your first phase of segmentation? It's pakis, fibrous reaganite. Right. |
|
| 173:53 | guess you could say that's a little cloudy compared to the clear epoxy |
|
| 173:57 | But the key here is to see a pack is distribution and need to |
|
| 174:03 | or fibrous morphology. Right. This what you get in the grain |
|
| 174:08 | Okay, ancient analog. I got examples in your slide seven. I'm |
|
| 174:18 | focus in on one because they're both . It's just a closer view of |
|
| 174:22 | other one. And your notes. , but what is the faces |
|
| 174:27 | These are goods. These were dasa green algae that took on a new |
|
| 174:31 | coating. So that puts you into persistently high energy environment. Right? |
|
| 174:36 | got the stirring rod. Let's look the first phase of cement. |
|
| 174:41 | relatively cloudy fibrous. I see packets . All right. So by analogy |
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| 174:49 | would be interpreted the original fibers Saraya cement followed later by a clearer, |
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| 174:55 | equal dimensional cement, likely a calcite another digest environment. Okay, but |
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| 175:02 | first phases marine sedimentation here. And obviously we had to create some |
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| 175:07 | on the sea floor long enough to at least a little bit of cement |
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| 175:11 | the grains. You don't have to long term stability to add all the |
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| 175:16 | at one time. Trust me, just takes a little bit of cement |
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| 175:20 | the sea floor to give you this sheet like crest that's not going to |
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| 175:24 | moved around by tidal currents or when agitation, then you can just keep |
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| 175:30 | cement. Okay, everybody see the again, this is marine cement. |
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| 175:35 | with the high energy Hewlett Greenstone. gravestones occur behind the Permian reef |
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| 175:42 | So both of these environments undergoing marine and then heimat calcite. We can |
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| 175:48 | heimat calcite exists in the modern because have a unique stain that the |
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| 175:54 | Okay. But uh when you go to the rock record, what happens |
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| 175:59 | high mag calcite? It expels the and re crystallizes the low mag |
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| 176:04 | You will never be able to prove sure that you had high mag calcite |
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| 176:10 | in the rock record. Okay. just need to know they exist today |
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| 176:14 | they likely existed in the rock So what are the two common examples |
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| 176:19 | the modern today? Uh If their cements their stubby bladed crystals like this |
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| 176:26 | an isil pakis distribution or they arm critic where they line cavities or occurred |
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| 176:34 | of contact. Okay, So, can show you one example and this |
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| 176:40 | from one of those Zula car grounds the shuttle photograph. I can share |
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| 176:44 | example of my critic. Marine cement is the thin section that shows you |
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| 176:49 | you IDs the red stain now is for calcite. The red stain is |
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| 176:55 | high magnesium calcite specifically. All So, the user magnetic, they |
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| 177:00 | take the red stain. The P are the nuclear er er Iraq |
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| 177:05 | they don't take the stain. So see all this reddish Mick right between |
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| 177:09 | grains. The question again is is poor filling cement or is this deposition |
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| 177:16 | Mick. Right? That came into system. So, for I |
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| 177:22 | you know from the field this is energy setting. And the other clue |
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| 177:27 | look at the zoo. Ids are about the same size and shape that |
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| 177:31 | you you're in a well sorted energetic . In fact, there are two |
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| 177:35 | of marine sedimentation here. The first is Isa pakis, fibrous or reaganite |
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| 177:42 | I showed you earlier. And the phase is this. And what's the |
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| 177:46 | that this is cement? Look at relationship right here. If this is |
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| 177:51 | filling of the critic material, it fill from the bottom up, |
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| 177:55 | Make a G A pedal. But at this stuff is plastered all around |
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| 177:59 | poor on the top and on the . You can't do this by mechanical |
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| 178:04 | . That has to be segmentation. once you see this, then you |
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| 178:09 | that these other areas are just a extent of that marine sedimentation. And |
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| 178:15 | else is missing here? There's no material here. Any other sedimentary |
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| 178:19 | It's all this uniform A critic Okay, You see how this buggers |
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| 178:26 | your relationship in the rock record. would call this a low energy pack |
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| 178:32 | . Right? But in reality this high energy eulogy grain stone that underwent |
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| 178:37 | sedimentation by a reaganite and then later heimat calcite. My critics cements. |
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| 178:45 | this is something need to be concerned . All right. Yeah, I |
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| 178:50 | you could you answer this question I think theoretically if this is an |
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| 178:54 | system and you had core, what would you see associated with this |
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| 178:59 | You see cross stratification, Right? these are high energy foods are rippled |
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| 179:05 | so that would tell you that this not be de positional Mick ride. |
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| 179:09 | you have preserved cross stratification. All . But here's an ancient example. |
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| 179:15 | mean, I've said this is from sunny land in the cretaceous of south |
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| 179:21 | . I was going through some of old project slides but a month or |
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| 179:25 | ago and I ran across this during is a this is a dead ringer |
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| 179:29 | what I just showed you in the right. Look at this relationship fluids |
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| 179:34 | about the same size and shape. the first phase of Isil packers, |
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| 179:39 | cement, and then there's all this . My critic fabric this is probably |
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| 179:44 | cement. Okay, this is probably hard ground fragment. Marine cemented material |
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| 179:49 | Mick. Right? And by by crystalline carbonate, by crystalline reaganite. |
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| 179:55 | right, finish up here. There's last environment where you get marine sedimentation |
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| 180:00 | that is a long high energy Okay. And that produces a fabric |
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| 180:06 | beach rock that could involve either reaganite calcite. Hi Mac outside and it |
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| 180:12 | involve either cement with ice, a distribution or cements at points of contact |
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| 180:19 | at the undersides of some of these . Okay, so beaches here's a |
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| 180:28 | view of an island in that I showed you the shuttle photograph yesterday |
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| 180:32 | some of that olympic sand builds up sea level To make an island. |
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| 180:38 | island is less than 500 years Got about five ft of elevation. |
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| 180:43 | what you see here underwater is the fluid sand right actively agitate every title |
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| 180:50 | and then adjacent to it is to part stabilised by sea grass and santa |
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| 180:57 | is not strong. Catalytic. But is stabilizing the sand doesn't |
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| 181:01 | It's borrowed. All right. And some of that stuff has been thrown |
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| 181:05 | on the beach. And you see white sand beaches are all analytic, |
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| 181:09 | some of them are have this darker here. That's the beach rock. |
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| 181:14 | . And remember on a beach right, Most low energy beaches are |
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| 181:22 | angle profiles. Right? General seaward , plainer stratification. But in the |
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| 181:28 | when the beat the energies were What happens to the beaches steepens? |
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| 181:33 | . All right. Oh, You see this off of California every |
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| 181:37 | . Right. And what does that if this is high tide and this |
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| 181:42 | low tide. It's low tide when level drops down here for a couple |
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| 181:46 | hours. That means all the sediment here on this part of the |
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| 181:50 | It's it's high and dry except for trapped by capillary force. Okay. |
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| 181:56 | the water trapped by capital Air Force what leads to precipitation of this or |
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| 182:02 | kind of cement. Okay, So we see these pendulum are Microsoft |
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| 182:08 | solid thick cement at the upper parts these beach rock profiles. All |
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| 182:12 | But beach rock looks like this. right. It's kabul that's broken |
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| 182:20 | It's a thin veneer. The cemented rock material is only about this thick |
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| 182:26 | so what happens in big storms as wash out some of the sand underneath |
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| 182:30 | by its own weight, it will and give you this pattern like you |
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| 182:34 | here. So, that's what creates fabric. All right. But it's |
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| 182:38 | a narrow belt. Right? And beach environment and it's all marines cemented |
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| 182:42 | all the water for segmentation is coming offshore marine, Right? And when |
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| 182:49 | look at then you can prove that the cement. When you look at |
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| 182:52 | cement, they're mostly the fiber Saraya cements. Okay. And what else |
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| 182:58 | you find in these beach deposits There's that financial porosity we talked about |
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| 183:03 | . Remember that big poor too big be explained by the packing of the |
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| 183:08 | ? Well, what held open this ? It was a trap terror pumped |
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| 183:11 | by the breaking waves. Okay. that gets preserved because of the |
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| 183:16 | right? That freezes that fabric And it or not, this can produce |
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| 183:21 | in the rock record. All So that that can be of economic |
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| 183:27 | . All right. So let's give five minutes to summarize here and then |
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| 183:31 | give you five more minutes on the side for lunch if that's okay, |
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| 183:36 | a good place to finish at the of this. So let me summarize |
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| 183:39 | sedimentation. It's restricted to high energy in shallow water. So these are |
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| 183:45 | faces that are prone to marine sedimentation platforms or ramps. What controls the |
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| 183:52 | ? You need the stirring rod for . It's going to be controlled either |
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| 183:56 | tidal currents or by oceanic swells or one wave agitation. That's where the |
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| 184:01 | winds come into play. The cement confined to the seven water interface. |
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| 184:06 | all your segmentation effects are right at surface. Okay, That's why these |
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| 184:11 | grounds are thin and patchy at any point in time. Okay. But |
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| 184:15 | exception is the reef because the reef this big structure and you can force |
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| 184:20 | deeper into that structure. So the cement could be more deeply distributed into |
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| 184:25 | reef complex in a sound body segmentation is always at the surface at |
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| 184:31 | one point in time because that's where title flow is. Or that's my |
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| 184:36 | wind wave agitation is. Okay, strong faces control on marine sanitation the |
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| 184:43 | that form our reaganite heimat calcite and think by analogy that was the same |
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| 184:48 | to the rock record. All So next weekend I'm going to introduce |
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| 184:52 | to our two and Member models. one in Member model is a shallow |
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| 184:57 | platform dropping off into deeper basin. define this as being roughly 10 m |
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| 185:02 | water depth or less, usually just or three m at the most dropping |
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| 185:08 | into a deeper water. And this be hundreds of meters to thousands of |
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| 185:12 | of water depth. This is the energy part of the profile and a |
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| 185:17 | dominated by oceanic conditions and oceanic conditions the swells. Oceanic conditions can create |
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| 185:26 | tidal current agitation depending on the, on the topography. So what do |
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| 185:32 | get along the margin here? Your energy faces. These are reefs and |
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| 185:36 | debris or high energy analytic grain Okay. And those are the faces |
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| 185:42 | the parental marine sanitation because that's where meet the stirring rod requirements. |
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| 185:48 | this is all low energy MMA critics all back here and of course down |
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| 185:52 | deeper water, not prone to much sedimentation. I don't know of any |
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| 185:57 | here. Of course. I told can get some marine sanitation in deeper |
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| 186:01 | with pauses and deposition. Alright, , that's, this turns out to |
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| 186:07 | what we're going to call the northern platform emerging model. All right. |
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| 186:12 | is not influenced by strong easterly trade . When you go down to the |
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| 186:16 | Bahamas keiko's platform, the area that worked and published on, you're going |
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| 186:21 | see, we have the same We still have oceanic influences operating right |
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| 186:28 | . But what's different when this trade blow anywhere back here, The shallow |
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| 186:33 | to be agitated, gets agitated on persistent basis? And those grain |
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| 186:38 | including New IDs can be marines cemented here. So the trade winds, |
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| 186:42 | strong trade winds expand your area of sedimentation. Okay. That's a change |
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| 186:48 | fizzy graphic setting. That's a change the weak easterly trade wind bill to |
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| 186:53 | strong easterly trade wind built Over about miles or over about four or 5° |
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| 187:00 | will change. Okay, and then carbonate rants. I define this yesterday |
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| 187:07 | a gradual imperceptible change in slope as go from land out into the |
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| 187:12 | The Classical Rand model is defined as a slope angle of one degree or |
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| 187:17 | . We always extension. We always that slope to fit everything into a |
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| 187:22 | . But in this model, where's focus of high energy is close to |
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| 187:27 | shoreline, where either tidal currents or wave agitation impinges on this part of |
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| 187:32 | profile. So this is the part the profile. Pronto marine sedimentation behind |
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| 187:38 | sand bodies or small little reefs that occur right here. Low energy um |
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| 187:43 | critic lagoons and tidal flats not prone marine sanitation. And of course, |
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| 187:47 | you go deeper, not good site marines, invitation either. Right, |
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| 187:52 | , so you see how the segmentation fits back into our deposition of |
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| 187:56 | You want to be Risking that. If you're doing risk analysis on the |
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| 188:01 | , The high energy faces, you to risk that into your evaluation. |
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| 188:07 | . What's the likelihood of having destroyed lot of prostate on the sea floor |
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| 188:12 | marine sedimentation. The mayor may not great in a reef. Probably not |
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| 188:18 | important in sand body system because you stabilize the whole sand body long enough |
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| 188:22 | cement it all up. So it's not going to have any detrimental |
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| 188:26 | Okay. All right. We'll put again, we'll put all this in |
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| 188:30 | next weekend when I take you through environments and then you'll see how this |
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| 188:34 | back to our play evaluation toward the of the segment. Yeah. |
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| 188:39 | so five after 12. So see back in an hour and we'll carry |
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| 188:45 | with this dye genesis story. Yeah, yeah. I'm going to |
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| 188:54 | here. I'm not going anywhere. Yeah. Utah I think I'm going |
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| 189:11 | stop this recording and because I think files are still going to get too |
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| 189:17 | if we do the whole day. mhm. Let me try to say |
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| 189:27 | . This part of the |
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