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GEOL6350-Advanced Structural Geology - Day4 PM 02-26-2022
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01:11 Angela, are you back? we'll wait few more seconds for Angela
01:22 come back. Right, okay, start this next hour or so.
02:52 about salt and shale tectonics, primarily tectonics. Okay, so in the
03:02 we're we're here to spend about an or so on salt tectonics. Even
03:09 we started late, I think we'll landed around five p.m. I think it
03:12 full and on time. Okay. , so on the on our structure
03:22 of fortune here we're going to be about extension of salt tectonics in this
03:27 of the diagram and both thin skinned salt tectonics up in this part of
03:32 diagram, extension of salt tectonics and of small tectonics. So first we'll
03:43 about the physical properties, assault. factors influencing salt movement and then the
03:49 types of autochthonous assault structures. A assault structures are ones where the mother's
03:57 is still in place. The original is still in its original de positional
04:05 . Um Different types of a taco structures um are active cheers, man
04:13 structures and passive down building type We'll talk about mega flaps and overturned
04:21 related to the salt reactive dye appears the dye appear is filling in the
04:28 created by extension. And then we'll about a locked in assault structures with
04:35 has migrated up to a higher Higher strata. Graphic level informed on
04:42 and related structures at that higher structural . We'll talk about the influence of
04:46 false salt sheets? Assault corps Many basins and shale tectonics.
04:58 so what is salt? Salt is evaporate. It's a mix of common
05:04 mostly highlight and hide, right? typically intermixed with lots of thoughts of
05:11 beds and these are the average physical of salt and and hydrate the density
05:20 velocity in feet per second and velocity meters per second. No kidding.
05:31 the most important thing is the density salt. This compares the density of
05:35 as a function of depth to the of various sands and shales shown
05:42 And what this shows is that depth than about a kilometer. The salt
05:48 less dense than typical sediments. It's depth. The salt is more dense
05:55 typical sediments. And this is the driving factor in salt tectonics. Now
06:08 philosophies of salt are also important because generally the velocity of sediments is less
06:20 the velocity of salt in that shallower , deeper depth below about a
06:25 And then we'll get these seismic velocity down below the soul. These are
06:34 real. They're just an artifact of difference in velocity between the salt and
06:38 sediments in the shallow sediments. Um sediment philosophies are less than the velocity
06:46 salt. And that gives you these pull ups on that again, or
06:51 an artifact of the seismic philosophy and two different structures. Okay, so
07:00 are the factors affecting salt movement, , inversions or buoyancy, differential
07:12 density, extension, contraction and gravity . So these are all the key
07:21 influencing salt mm. And these are sections showing these different factors. These
07:30 factors affecting development assault structures. One just the difference in density leading to
07:37 . You load the salt here and , driving it into highs or die
07:43 in this location. All right, a different type of differential spreading here
07:53 you loaded in the middle and the salt evacuates to those points,
07:58 points where there's less loading giving you and ultimately things called turtles. In
08:06 location, gravity spreading telekinesis where the is less dense than sediments as it
08:15 up to the serial surface, it and it flows out sometimes even assault
08:24 and naps in the so a slope the gulf of Mexico group. But
08:32 also thermal convective telekinesis where you get convection within a big body of salt
08:40 itself like this and then an extension contraction extension. Whereas as you pull
08:47 apart, the sediments are extended in salt flows in to fill those gaps
08:55 by the extension of subsiding here, up, even extending to the surface
09:01 these relative highs um and in contraction forms the major detachment horizons gives you
09:11 according to clients like this and can the can conform the detachment layer here
09:18 to salt extrusion up shallow, following thrust trajectory. So these are the
09:27 tectonic elements terminology and cinematics for So in cross section, I'm showing
09:33 here and here too large salt True as you load the flying through
09:40 salt bodies, that loading drives assault the crest of the the salt
09:48 The salt structures are called salt walls appears or pillows depending primarily on their
09:56 . Um the areas in between our basins or mini basins or sinks or
10:02 clients. Bye. Okay, so a schematic showing the evolution of of
10:14 body and specifically of something called a . So we start with thick salt
10:21 here, begin to load it in centers here and here that evacuates the
10:28 from the point of greatest loading and them into the areas of salt.
10:36 highs the salt highs, creates sedentary over them as the salt continues to
10:44 eventually. This the salt goes away in the base of the sediments.
10:49 the basement floor here and this is is termed a Well, you get
10:54 here and one here. Once that is formed, the salt is no
11:00 , there is no longer free to laterally and so mm hmm. The
11:08 moves out. These fins are subside are deposited welded here and here and
11:19 themselves form local depot centers or mini and then continues to drive what are
11:26 is left out of these wells. and lows, resulting in this kind
11:33 structure called the turtle structure where you thick the thin on top bounded by
11:40 thick mini basins, with the sediments off to the flanks of the turtle
11:54 . Okay, how salt rises in crust. There are different mechanisms
11:58 one is called Reactive Pearson where the adjacent blocks are extending, you gotta
12:05 in here in the middle and the flows in to form to fill in
12:10 the scrub in. You get active where the buoyancy of the salt itself
12:17 it upwards and the forms are or the overlying sediments. This can evolve
12:28 an erosion along pierce mint structure shown where the salt flows up the bounding
12:34 flow down and once the salt reaches surface you can extrude Sylvia really along
12:41 surface. We also have thrust placements the salt is forms the Tacoma and
12:51 carried up along the thrust itself. dr pierce smith structures where the salt
13:01 flowing up due to its buoyancy, low density and the overlying sediments are
13:07 folded over it. So it's it's of a version of this where the
13:13 has continued to flow upward and continued deform the overlying settlements and then passive
13:22 mint like this where the salt just up vertically and pierces the bounding settlements
13:28 actually performing the overlying sediments. so a toxin. It structures our
13:39 die appears and canopies and we'll talk the geometry of each one of those
13:48 the gulf of Mexico. We have different salt tectonic provinces on shore,
13:55 , Onshore texas Louisiana. So here's the shelf, Here's the Louisiana
14:00 of texas shelf is back here. , the slope is here and the
14:06 slope is down here. I'm sure get these rollers, pillow stones,
14:12 appears all still related to the auto related to the original mother software.
14:20 you get to the shelf, we autocracy ist die appears in many
14:25 Were you um assaults have more vertical . You have time appears. Mm
14:30 . Many basins, big de positional , but the still the salt is
14:35 related to the in place Mother salt . As you progress out onto the
14:43 , we move into the gelatinous salt where you have di appears in many
14:51 , but they're related down to lock in salt, which has float up
14:55 the mother layer here to form a strata graphic level here, what's called
15:01 nap here and then that nap is by the overlying de positional centers right
15:08 finally progressing down to the edge of and the toe slope. You go
15:13 the zone of elephant assault canopies and appears where these structures now have been
15:20 loaded and extrude it upward to form naps canopies and some housing counties.
15:32 you. So these are examples of of the types of structures, ensure
15:40 get. Things like this that are pillows. Low relief structures where these
15:46 into high relief structures, they become or die appears all still related to
15:52 top mother salt layer on the We get talk to this guy appears
16:02 many basins, things like this where salts bodies are still related to the
16:08 assault layer of the original motor salt here, but they have been extruded
16:14 to where they formed some horizontal layers are then loaded to form. Mhm
16:19 basins depot centers and in successive di when you get down onto the slope
16:30 are totally locked in assault bodies like like this where here's the seismic
16:36 here's the top assault here. The salt here. Another depot center a
16:42 basin being deposited on top of the and the combination of that loading and
16:48 downslope base of the salt because the to move base inward and upward into
16:55 young into the next mini basin compressing next mini basin. This is an
17:02 of a seismic section across the map of the uh 60 escarpment. You
17:08 the salt body here, sediments sediments here and the loading of the
17:15 here dries assault upward and basin world driving assault in this direction. In
17:25 cases giving rise to overturned limbs beneath salt here. So salt flows and
17:37 . These things that we see both the on shore and on the
17:43 We have low relief pillows with primary . Send clients where the simulates sediments
17:53 Pearson die appears. Hi relief die that move up into the sentiments with
17:59 primary and secondary rims inclines, eventually to turtle structures where the dye appears
18:08 high enough and become cut off. get these bulbs and teardrop shaped salt
18:14 . And finally, as these as the salt moves upward and
18:19 it evolves into canopies what are called yours and salt sheets and tongues.
18:27 these sequence of structures represents different stages development, different stages of development due
18:34 loading and continued movement of the salt . So first the salt rollers and
18:44 . Okay, we see those on in texas and Louisiana right down dip
18:53 this, maybe a Taco Falsone. they represent structures like this low relief
19:06 where the soldiers evacuated in one area in another area. And you get
19:14 confident normal fault Robin structures evolving over flanks of where the salt has
19:25 Here's another example, this is a relief salt pillow from the nancy field
19:30 Mississippi. You see the salt down sediments overlying it here, folded into
19:37 dreadful old here from slight thickening of sediments off the flank of the crest
19:44 the salt party. The overall of relief and decline of low relief dome
19:54 increased relief. We get these intermediate salt down declines where the salt now
20:00 higher lease structure. More of it been evacuated into this area and as
20:06 moves upward. All right form's depot or rims in clients that then continue
20:12 collect sediment and continue to drive the by loading it here they continue to
20:18 it upward. The overlying sediments are into grabbing like structures and typically the
20:26 Robin fault extends into insoles into the body here with other secondary constant faults
20:34 up from that progressing effort from Here's a higher relief. Sultan
20:44 This is from the Pool Creek Mhm. Also in Mississippi. Somebody
20:51 , top salt here basalt here to . Finding sentiments here and here and
20:57 this crustal collapsed, grabbing over the of the salt. You see how
21:02 center is thickened from the crest to flanker assault on both sides on this
21:09 and on this side from here to that thickening loads of salt on the
21:16 and drives the salt into the structure drives it up vertically, resulting in
21:22 crystal collapse and decline. And again main crystal, the main fault to
21:27 crest of collapsed synagogue in decline comes and souls into the salt. So
21:32 salt surface itself sounds like a fault these other conjugate faults tip out into
21:39 salt body so bob's die appears and where we have higher relief cell
21:51 This is an example of a seismic from assault di appear. You see
21:56 nice domo folding of the sediments around salt. This happens to be the
22:01 reservoir horizon. Thank you. Gas contact is here. Water contact is
22:09 here and you have a nice bullseye of structure with assault type here in
22:13 middle. One of the difficulties in is determining where is the salt
22:20 As these beds get rotated up to and higher dips the imaging becomes worse
22:25 worse and you don't really know where bed where the sedimentary beds terminate in
22:32 the salt flank really is. okay, evolution of active salt die
22:44 . So you have cartoons here showing evolution from pillow stage here where we've
22:51 a little bit of loading ramps, formation off the crest of salt
22:56 Is this? These depot centers You get this thickening of the sediments
23:03 to the salt. These beds that thinned out of the salt right now
23:12 forced down here. So their fins in the lows. This forms what's
23:17 the rims incline. The loading progressively the salt upward until eventually the sediments
23:26 against where the base of the salt to be cutting the salt off from
23:30 supplies here and the continued loading These die appears laterally in the
23:37 assault near the on the subsurface at surface or near subsurface excluding the salt
23:46 a toadstool are are now time Right? This shows a sequence of
24:04 structures progressing from a relatively up to dip in this case, into the
24:10 of Mexico. Oh, Top It's salt in place here. Um
24:17 higher and higher relief structures as you into the basis, starting with low
24:22 salt, pillows and rollers top tip relief salt and declines in the
24:31 mm hmm. Progressing into hi released pillows and dieter of salt walls.
24:40 these extruded manicures from the tops of diabetes as you get further and further
24:47 depth. Mhm. The centenarian voting eventually pinch these off in giving you
24:54 terrible shaped soft money. Alright, structure contra maps of some of these
25:08 structures from the east texas basin. , hi relief salt pillow here di
25:15 here with essentially vertical sides. Toadstool , somebody's here, bones, mm
25:26 . Structure concerts on those moving up or less vertically or inclined with a
25:34 burn extruded for wider diameter section at top of the structure. And then
25:44 down dip. Further, you get simple salt and declines of rollers where
25:49 salt is essentially a plunging neckline. , all right, we see the
26:00 types of assault structures in other And this is the north west german
26:08 . United Kingdom is here onshore Netherlands Northwest Germany are here. One Norway
26:18 here in here, you have a of um Triassic salt deposit that's now
26:29 into a series of these same types structures and this is the paleo geographic
26:40 of this salt is Eckstein salt in Germany. All right. Um the
26:48 was deposited in these yellow basins, plastics and Sakas in these areas,
26:57 up the mother small layer at the of the Triassic in here. So
27:08 is the progression of salt structures that get moving mm hmm, down debt
27:13 southeast to northwest. We have progressively and thicker salt. First we have
27:20 low relief pillows, The salt stocks die appears hi relief stocks and die
27:28 here in salt walls where these die , Can grow laterally emerge into a
27:36 one continuous salt wall. The evolution these structures is just as we described
27:49 , where you start with the mother's in this layer here, when the
27:54 deposition, as you start to load , it starts to evacuate, forming
28:00 and highs the lows, then become centers or many basins and it's kind
28:06 a circular process where he deposited sediments , the loading evacuates the soul.
28:13 subsides and forms of accommodation space for more and more sediments, mm
28:21 And so as these things progress with salt thins thickens locally into these pillows
28:27 die appears and can extrude severe really the at the land surface.
28:46 so here's a detached di appear from Northwest German basin. Here's the 16
28:51 here assault has moved up this fault has been evacuated completely from the salt
28:58 by the loading along the flying downloading tries the small upwards, giving
29:05 to overturn beds beneath the flank of salt and this this canopy shaped domed
29:11 over the top of the salt, an example of a typical dome from
29:21 north west german basin, the greenhouse salt dome. The 16 starts
29:27 steeply dipping beds adjacent to the salt , where the salt is forced its
29:32 up through those through those sediments, to the Sylvia real surface where the
29:39 and extrude reform cap rocks and salt at the at the top of the
29:54 . Alright, so these are cole canopies from the salina basin in
30:02 Mhm. So here's a a cross , here's a three D diagram in
30:07 cross section. You see the what's of the thin mother salt layer
30:12 at the base, the salt has upward. It's been extruded from those
30:18 mother shot layer up to a shallow here and here. And is that
30:23 continues. These individual bodies grow and cole os. So you go from
30:31 bodies like shown here into one continuous . But your nap is shown here
30:37 three D. They look more like where you have a series of coalesced
30:42 bodies at the surface fed by individual stocks at various locations throughout the
30:55 Okay, the mechanisms reforming. These talking, assault structures and here.
31:04 Frankie the pillows, the dye bulbs and teardrops canopies and manicures and
31:11 sheets and tongues are related to the auction itself. Okay, so here's
31:18 example of a the salt pillow. is one of your exercises. You
31:24 the top salt here. Somebody here here, These flanking sediments coming up
31:33 the Domingo structure here, false up in the section high in the
31:40 Um, what I want you to is take a few minutes you have
31:45 in your handout right to interpret the , the faults and the sediments and
31:51 how they formed. And so you to take a look at this.
31:59 the fault up here. Extrapolate them into the, into the salt
32:04 decide where the major through going fault and what the consummate intersecting relationships are
32:12 the other faults and the salt body . So, uh, that's
32:19 I don't know, take 10 or , 10 minutes to work through this
32:24 then we'll bring it up and talk it. Okay, let's let's talk
40:14 one over. This gets, it's a little difficult just by the size
40:18 the seismic section defaults or not as results as they would be in real
40:24 . Um, so we have the of the salt here and you want
40:29 follow these reflections up to a crystal somewhere about here and then back down
40:35 other side. So these two salt connect up the base of the salt
40:40 continues through some horizontally like that on strong reflections at the bottom and then
40:48 gets you up into interpreting these crystal fault at the crest of the
40:54 Mhm. Now from the data that you the green was a little bit
40:59 on this side than on this So when you extrapolate those green events
41:05 , you end up with a normal on the green event in in this
41:11 . So that means that the master for the system has to be coming
41:18 from here down through about here, to create this normal offset on the
41:24 and then soling into the salt layer . And one of the key things
41:28 is done the dipping to the giving you this normal offset and soling
41:34 the salt body here. And then other faults are antiseptic and synthetic to
41:43 . This anesthetic comes down approximately yeah, intersects the main fault
41:49 synthetic fault comes down here intersects this here and this you get the sequence
41:57 fault just by working upwards from this , interpreting this fall. First This
42:05 . 2nd, because he's it looks the major off next major offset when
42:10 start to drive your orange up into and then the orange steps up a
42:15 of loops here and finally to here get the normal offset that's required by
42:21 basin bounding. Following on this flank salt is completely welded out. That's
42:29 by these two dots where the top the salt has touched down onto the
42:33 . There's no longer any salt present . And the overall evolution of the
42:39 comes from um the loading of the on the two flanks of the salt
42:46 and here. Mhm. The normal here and the slight thickening of the
42:51 on this side relative to this This has gone down great around this
42:57 accumulated more sediments than this side And that's a cute that's consistent with
43:04 welding out of the top and based over this area of greatest deposition.
43:14 . All right, did you did follow that? Did you see the
43:18 in putting those things together? Any or questions on that? Okay,
43:33 move ahead. Okay, so here's example of basically the same type of
43:43 our salt pillow here, flying sediments thickening downwards, rotating onto the
43:52 Assault, Meine falls in the festival and coming down through here soling into
43:58 top of the salt here and then other. Can you get in synthetic
44:05 , intersecting assault and intersecting each other higher in the section. Okay,
44:17 active. Die appears. These are appears where um the chairman of the
44:23 sediments is due to the buoyancy of salt and then we have passive di
44:29 we're molding of the original tabular assault down building creates a salt diet here
44:37 these two are kind of complementary. see that as we go. It's
44:42 to make a part and member distinction active versus passive. What are distinctly
44:48 are these reactive dye appears where you rise of salt in response to extension
44:55 faulting in the overlying sediments to pull overlying sediments away and create a void
45:00 the salt to move up into so diet appears. Those where Pearson of
45:09 sediments is due to the point of salt. Yeah. And those typically
45:17 at these depths below about a kilometer the salt is lower density, then
45:22 sediments due to that difference in the salt is going to move upward
45:28 to form the overlying sediments. Here's an example that where we start with
45:42 this is from the north west german . We start with the muscle mother
45:46 while you're here with the deposition and on the flanks, you get a
45:51 structure here with continued deposition loading on flanks. These parts of the soul
45:58 become smaller and narrower and the Celtics upwards performing the overlying beds here so
46:07 beds are not pierced by the salt and fold it up for an adjacent
46:11 the salt layer and as that you get a more teardrop progressively more
46:16 shaped salt body at the crest of structure. So here's a model showing
46:27 evolution of that stirring. Starting from with a small relief. I'm
46:36 Starting from here with no no Motor software here, slight filming here
46:44 as you move upwards this way until get a higher and higher relief pillow
46:50 here. Where while your pillow has evolved into sort of a diet,
46:54 more highly structured and as the voting , the salt body continues to move
47:03 and when you get up into that where the salt body is higher destiny
47:08 sentiments. Then you start to get lateral extrusion of the salt to get
47:13 teardrop shape. Okay, so here's example of the evolution of an act
47:31 salt di appear starting here with the salt layer. The original autopsy and
47:36 layer loading on the flanks here and , creating a low relief pillow here
47:43 progressive loading here. This subsides this that was then rotates downwards to get
47:51 rims inclines adjacent of the salt. salt excludes upwards, deforming the overlying
47:59 and eventually when this salt reaches the surface but excludes laterally summarily. Once
48:06 salt is now denser than the sentiments you this soft overhang. This toadstool
48:13 shape, but it's still shaped Now, the fault patterns we get
48:23 to these salt die appears are typically radio fault pattern. We're here.
48:28 looking at several salt domes here here and here. These are structured contours
48:34 the salt tone. Hatch your pattern the middle is the salt itself and
48:38 false radiate outward from that in this pattern. Here's here's another example that
48:55 and cross section here. Salt here contours showing the conical shape around the
49:02 body. Wow in cross section. here, you see the salt body
49:08 up here with these sentiments coming up to the salt, moving upward,
49:16 by the salt tracked out by the . With these radio falls emanating from
49:23 salt body. Accommodating the extension of layer is is forced to move out
49:30 to the salt. Mhm. Here's here's another example um um you see
49:42 chemical shape here, the crest of salt body here, structure contours on
49:47 map level the reservoir horizon here, radio fault pattern. Yeah. If
49:53 connect the structure contours across the gaps we did on the first day,
49:59 see these dip in dip in different , but each fault has only one
50:06 of dip no longer. There's no across no crossing of the fault contours
50:16 these gaps. And this again gives the sense of up and down up
50:21 down along each side of the Okay, passive di appears are down
50:34 and this is related to the differential of the sediments. And the idea
50:39 that the salt, it's all kind states football sentiments go down around
50:48 And so this was first introduced back 1933 by Barton Partners and the idea
50:54 that the tops of the salt layers passive on an emergent near the ground
51:01 of the sea floor and the flags buried deeper and deeper under the weight
51:06 the under of the surrounding sediments, the weight of the continued segregation.
51:13 down building requires differential loading an assault by the overburden. Mhm. In
51:19 original model, the salt is passive the sea floor. More current models
51:27 that the top of the cell it's determined by the deposition and erosion
51:31 history of the overburden and the dye that we see are typically formed by
51:39 . A combination of this down passing down building and active Hey
51:45 Oh, I want to say about this active Pearson of the salt
51:54 So, here's, here's the original building layer. The idea is,
51:57 start with this salt at a constant here. As basements of size sediment
52:06 , sediment fills in the gaps between salt bodies, drives the salt from
52:13 lows into these more dietary structures. top of the salt remains at the
52:19 relative data throughout this process until eventually salt is completely evacuated from the same
52:27 . You get a weld here where salt is completely evacuated, forced into
52:32 salt. Dieters on either side and continued subsidence and sedimentation. The salt
52:42 get squeezed laterally to form these to shaped light appears. So this is
52:49 conceptual down building model for di appears So molding of passive DI appears sand
53:05 exceeding a critical thickness, maintain the that they can't be penetrated by the
53:11 . The stiff okra burdens influenced the of the on the underlying passive or
53:18 dye appears in the deformation of the Di appears by the stiff sediments is
53:26 to as a process called molding. these factors influencing the dye appears,
53:36 , the rate of overburden growth and . The rate of salt uplift the
53:43 of original mother salt. The slope the basil salt layer, if there's
53:48 slope to it in the orientation dip abundance of false. All these influence
53:54 shape of the evolving sort bodies. an example of salt bodies in the
54:04 of Mexico in the allotment assault structures are termed mega flaps in the scientific
54:11 here. Oh, the mega flaps . These sections where the sediments have
54:17 uh huh. Abort too high or overturned angles adjacent to the salt.
54:26 the salt body is shown here, hmm. Original top finished mother salt
54:32 here. Now we have a totally in a snap salt later here and
54:40 these basins subsided on the flanks, salt here was evacuated and moved
54:47 carrying these sentiments with it up to now of sub vertical orientations.
54:58 so here's here's an example of how form starting here with salt layer here
55:08 these green sediments on top of it continued sedimentation assault evacuates from these
55:15 you get depot centers here and More sediments accumulate here in this continuously
55:22 to this, these mini basins sinking the salt driven by the weight of
55:28 newly deposited sediments here, working downward assault awkward in this direction, bringing
55:36 layers up higher and higher and continuing with a series of steps and still
55:46 eventually get to this step where the is is welded out here and nearly
55:52 get out here. The sediments are vertical on the flanks of the salt
55:57 and now, with this last continued the salt extruded laterally informs this overlying
56:04 wear or map two. Okay, these these mega flaps are important exploration
56:17 because they form three way closures against flank of assault. And the the
56:26 capacity within those is determined by the capacity of the salt. The salt
56:33 the ultimate octave and lateral seal for mega fat traps. And we saw
56:40 when we talked about mechanics and fracture that that salt sealed capacity is more
56:46 less equal to the fracture gradients. as again, this comes from studies
56:51 Oman where we can compare the pressures temperatures in fluid inclusions within the salt
56:59 to the fracture gradient and what we is that those pressures and temperatures reach
57:05 maximum that's bounded by the fracture So the seal capacity within these
57:12 These guys is determined by assaults. capacity which is equal to the fracture
57:20 , the minimum horizontal compressive stress. , so here's a sequence of diagrams
57:29 how these things can evolve. Starting an inclined salt layer here. Thin
57:36 , thick here, this thin then as served as a local depot
57:42 Yet more and more sediments here. you get more and more sediments
57:47 you love the salt assault moves up this direction, leading to pinch house
57:52 assault bodies here and individual pin shots the individual layers. Up here with
58:00 movement, The salt goes continues eventually welds out here you get a
58:08 flat with some vertical orientations here. salt of the crest extrude laterally,
58:15 hmm, forming an up dip seal these bodies and potentially forming a subsea
58:22 extruding out onto the sea floor on of these unwrapping layers. Alright,
58:34 here's here's an example of that from paradox basin, the in Utah,
58:41 gypsum valley die up here. So have to paradox salt here. Here's
58:48 seismic section across this. This is Unsure two d. seismic. So
58:54 a kid can expect very poor you can see the sentiments coming up
58:58 this direction. And then do you lose imaging around the cell body itself
59:05 in part that's due to the salt protest due to the verticality of these
59:11 . Does it come up onto the of the salt? Mhm I
59:19 So here's here's a restoration that working oldest to youngest shows how these things
59:27 . So, here we start with Mhm into pennsylvania are talking. Assault
59:36 here, we start to develop, to deposit sediments on top of that
59:42 to local depot centers of concentration of salt pillow or All right, You
59:49 , basically a pillow or a roller this location. With continued sedimentation,
59:55 salt evacuates, flows into the crystal location that happens on both flanks this
60:03 and this frank leading to the rotation the salt flying adjacent beds to steeper
60:10 steeper dips fault founded on this rotated passively by folding on this location
60:19 continued sedimentation. Um you get more more sedimentation here, assault evacuates eventually
60:29 layers progressed downward. So, what it thin here? Yes, Now
60:35 downwards, so it's deeper in the here, and you get it's thinning
60:42 the salt flank here, while the guides thickened onto the soft drink
60:49 and these beds on the opposite flank progressively rotated to higher and higher angle
60:54 adjacent to the salt as the sediments deposited here and forces underlying salt out
61:02 the dye appear. Yeah, so there are two to kind of
61:14 models for how these salt flying bodies ? Mm hmm. one is by
61:26 um limb rotation which is shown here you start with the limb here,
61:33 salt ISO is evacuated here. The are deposited here and this is progressively
61:39 to higher and higher angle where this point remains relatively constant through the evolution
61:46 the structure, eventually giving you this vertical them here with this king band
61:54 . The idea is you start the geometry, but now I'm going to
61:58 this on top of the salt and a vertical limb here and then move
62:04 limb downwards as I thickened sediments on flank. Uh huh, rotating this
62:14 um to progressively higher and higher angle it becomes vertical at this point.
62:22 . Now, with with this king migration, we would expect to see
62:28 lot of deformation deformation bands, things that resulting from the migration of this
62:36 fall through the sediments which is not . And so we think this little
62:43 model is a better Kinnah Matic model how these things evolve. Okay,
62:54 here's a physical model on the How do we get these softbank over
63:00 overturns sediments here. Soul body is here as in red initially, the
63:09 relief of this, inhibits sedimentation and burial. The sentiments on the flank
63:17 lap to talk about salt partially burying top of the dye appear and depending
63:24 the dip of the top of the appear. It may not be buried
63:27 on all sides. Okay with continued , this goes down relative to the
63:38 . This goes down relative to the . The salt states porter moves
63:43 Knowledge native to the sediments on That relative motion takes these sediments that
63:50 initially unwrapping the salt deposited on the and rotates them to near vertical positions
63:57 in your vertical orientation, suggestions of . Okay, alright, reactive dye
64:09 . These are ones that form in to extension. So here's a progressive
64:17 of how these evolved. We start a grommet here. Conjugate normal faults
64:23 , tipping out at the base of salt as these two adjacent blocks move
64:29 to get more and more normal enlarging the gravel structure and from below
64:34 salt moves in to fill that gap by the extension, eventually resulting in
64:45 moving up to the sub aerial Alright, so here's here's an example
64:57 a reactive dye appear to see the here. Top salt here, interpreted
65:06 here on interpreted line here. And you see all these. Mm
65:12 Normal fox cards, you get normal extending into and tipping out into the
65:17 body here. And so the sediments the shallow section here are moving apart
65:23 this direction, in this direction and salt is flowing in to fill that
65:29 that's created mm hmm. Just like like we see in this model
65:41 Okay, um so here's another This is from the 16 salt in
65:49 North Sea seismic section here, line interpretation of the seismic section here.
65:58 here, immediately below this dark dark layer. And here you see all
66:06 normal faults forming shallowing section. So this shallow section extended in the horizontal
66:15 , the extension he was accommodated by faults in the shallow section and by
66:21 of the salt upward to fill the gap is created in the in the
66:26 section. Okay, a lot on structures. So now we're going to
66:38 about these locked in assault structures where salt is no longer related to the
66:43 salt layer wherever it started from. . And here's an example where the
66:50 is moving up section in the downward . What over the crest of the
66:58 body. We get these normal or normal faults soling into the salt relating
67:05 the extensions. This whole thing moves dead as the sense that down dip
67:12 occurs, the base of the salt in a thrust kind of scenario and
67:18 these overturned sheared bets at the base the soul. So we have extension
67:23 features over the salt and contraction als features right adjacent to the base of
67:31 salt. So here's a the model how we potentially get these overturned
67:43 The idea is you start with a napa salt body like this or like
67:49 as it moves down there, sediments are initially deposited on top of it
67:57 rotated over to an overturned position below below the base of the song.
68:03 this thing is moving, moving down , carrying these overlying beds like a
68:09 a conveyor belt down dip and overturning at the toe of assault body and
68:15 them to create these overturned beds that see at the base of the
68:23 And this this seismic examples. Maybe unique example because you can see these
68:28 coming along like this and then becoming at the base of the salt
68:38 Okay, alright, so we're here the gulf of Mexico. We have
68:42 tectonic strata, graphic provinces related to salt here we have the shelves detachment
68:50 basins and die appears down dip. have the tabby assault bodies for the
68:55 basins with the many basements and a of salt. And at the far
69:01 , deep section in Perdido full belt the Mississippi fan belt here and here
69:06 have completely locked in assault forming contractual structures. Mhm. So, we'll
69:17 at a series of regional sections across going from up to down dog.
69:29 here's a section from offshore Louisiana. lot of vertical exaggeration in here to
69:34 the different orientations, a lot of fault extension. Up here. Mini
69:43 formation here di appear formation here assault bodies that will look at in more
69:49 in here related to the many basins then down dip. We get these
69:54 cord and declines and salt cord thrust going out into the Mississippi phantom belt
70:02 escarpment. This is a 1-1 version that so that you can see that
70:10 the true vertical relief on these is rather small. So some of the
70:19 discoveries related to the salt tectonics in gulf of Mexico are look to Atlantis
70:26 mad dog bodies here at the tip your locked in assault. Right the
70:37 way to solve evolves is through this of wedges And that's shown here where
70:44 looking at a sandbox model here with layers deposited here. Initially we had
70:51 body extending all the way up here those layers were deposited and progressively moved
71:00 . This way that moved the salt were down, dip into this fiscal
71:07 , translating and thickening salt here this this then forms the locust for on
71:17 normal faulting role of Randal clients rule sin clients adjacent of the salt as
71:22 moves up and and down down, and down. So here's a sequential
71:35 showing how that evolves. We start the gelatinous salt here with a slight
71:43 dip dip to it down, basically to it pinned up here, begin
71:49 deposit sediments up here on the up section as those sediments are deposited.
71:55 drive the salt basin word the salt and lifts the overburden here, deposition
72:05 here. Moving down basin in this here, still squeezing out the
72:13 forcing assault to move further down forming a rolling Monica klein here,
72:20 . Well here Shown, shown here the two dots in generating a depot
72:27 . Depot section session here. Um then becomes the locus of continued sedimentation
72:35 more loading of assault and progressive inflation the salt and movement of the salt
72:41 the down dip direction. This is example of that from the the santos
72:54 . We're here, there's the base here basalt here, normal faults soling
73:03 the salt here, and you see overlying sediments progressively rolling over into that
73:11 , whether in a position to track salt on progressively based word, with
73:16 and more segmentation, I think. now this this evolution and appropriation can
73:30 result in formation of salt sheets. we see the same models, but
73:38 the difference in that there are steps the basement below the salt stick assault
73:43 in assault here, even thinner salt as the sedimentary wedges pro grade basin
73:50 and deposit the salt deposit on top the salt here and cause assault to
73:56 the assault came down. We saw the first section, it also can
74:02 up to creating a passive wall or di appear and eventually assault sheet at
74:09 location where the salt has been evacuated this di appear enforced up to the
74:15 floor to form these little optimus So here's an example of the sheets
74:28 due to this appropriation from the gulf Mexico. We have all the sedimentary
74:34 depositing here, evacuating assault from this location, forcing it downward or forcing
74:42 basin word in this direction into salt . In this area with thrust and
74:51 appears to the down depend on that existing basement faults can have a big
75:00 on the salt geometries. So, an example from on the southern North
75:08 of for UK, the Netherlands. , we have the original assault
75:15 followed by basement faulting here that deforms overlying salt layer, resulting in constant
75:23 faults forming over the trade fold here progressive loading on both sides of
75:30 The salt is evacuated from the sites loading into these relative highs here,
75:38 from here. Well, to this here, creating an assault high over
75:44 this basement step right here's an a seismic section across an example of
75:54 from the southern North Sea. You the top basement here basement normal fault
76:00 . 16 solid here. Mhm and what was once a continuous layer across
76:08 is now deformed into a thick, thin here driven by the deposition of
76:13 And another six year. So as evolves the deposition of loading here creates
76:18 depot center. It captures more sediment and more loading the force of assault
76:24 its original layer into these flanking highs here in here. It's interesting because
76:32 get a realistic normal fault along the of the salt body, but the
76:38 souls into the salt body and doesn't up with the underlying basement fault.
76:52 here's here's another example on seismic Horse crap in here. 16 salt
77:01 the top of that, right? the the salt originally extended from here
77:08 this direction and in this direction below Triassic defaulting created deposition of lows here
77:18 here. That then led to the of these Triassic and Jurassic sediments in
77:25 pillaging settlements, loading assault, enforcing assault from this location up onto the
77:32 first floor. Okay, salt sheets sought sheets. We mean geology is
77:45 this. Here's a seismic section across sheets from there. Um Line drawing
77:53 of the science section here with the body here totally locked in a
77:59 No no obvious feeders leading into that being truncated by the salt party and
78:10 sediments overlapping the salt body in Matthew salt sheets have this semicircular extrusion pattern
78:20 these things are moving out from up , moving out down to both directly
78:28 , dipping in a lateral direction. . So, a structural evolution of
78:40 these things of all. Starting here the oldest. Late Miocene, you
78:46 a simple diet, your type section progressive loading into the mm hmm younger
78:53 younger miocene. The sediment. The from the mother later here squeezed out
79:02 the salt sheet here. Moving up dye appearance. Mhm. Until eventually
79:09 here welds out the salt pinches off di appear and you're left with a
79:15 totally locked in this salt sheet Okay, so here's an example of
79:27 coalesced salt canopies from the santos We'll go from Mexico basement here.
79:35 salt layer here. All these salt appears and manicures here and here they've
79:44 and coalesced into one continuous salt body three dimensions. It's interpreted to look
79:50 this where individual codes to all kinds structures devolved laterally emerged. Okay,
80:06 . Here's here's another example from the of Mexico from Milwaukee, a rich
80:10 . See the salt here top song here, basalt along here, basalt
80:17 moving up section in the down dip um in other sections resulting in thrust
80:25 out here in front. Fine but no obvious source, no obvious
80:34 no feeder dike into the salt body . Alright, so this this is
80:48 reactive dye appear over in a locked this sheet. Assault body is now
80:55 optimists like this guy and we're going form more pillows in maine basis by
81:01 at the top of assault body like . That gives us this geometry with
81:10 body here, evolving hi relief structure , depot center here depot center
81:17 But as this extends in a downward in the shallow section you get all
81:23 conjugate normal falls that we see that soul into the salt. Um
81:31 the salt is filling in the the created by the lateral extension in this
81:41 . Okay. And it's sold cord on things like this. We talked
81:45 these with the Listrik Normal falls where have a line drawing and some sandbox
81:52 here. The salt layer here. . As we as we load that
81:58 get these Listrik Normal falls that soul the salt layer here in the salt
82:04 here then becomes a detachment layer from overlying falls. So in the gulf
82:16 Mexico there's terminology around this that's called the Rojo encounter regional fault systems.
82:27 refers to the salt nap layer of original original bedding parallel salt layer typically
82:40 ballistic normal faults in many basins sold that, dipping in the down dip
82:45 to the south. In some areas the salt evacuation is up section like
82:53 here, we just developed false dipping dipping towards the towards the current.
83:02 up in the object regional direction giving to turtle structures and role of random
83:10 in the innovation here. But because are dipping against the regional de positional
83:18 , these are referred to as counter fault systems. Friends, southeastern tip
83:23 the down dip and down deposition direction to the south. These are called
83:31 homer regional fault, whereas these are counter regional force. Alright, so
83:42 an example of Listrik normal falls into salt and within the apply apply asinine
83:47 in the gulf of Mexico. So we're looking at in a locked in
83:51 salt layer here. This from the layer for all these Listrik normal faults
83:56 into it. Mhm. Here's a restoration of that where these overlying layers
84:04 subsequently restored to a horizontal data. , that creates a gap between the
84:11 of the salt here on the base the salt here, creating this gap
84:16 is assumed to be filled recently have filled by salt. So when in
84:21 forward sense we think he's evolved by it locked in assault layer here,
84:27 centers loading that salt forcing the salt the overlying beds down deep in the
84:34 direction, resulting in continued de centering, centering deposition of basins in
84:41 part of the section of the lion . Alright, so he's these counter
84:53 systems evolve as the as the football basin work. So here's a block
85:01 showing that pre faulting with the salt with extension and downward deco movement movement
85:09 the hanging wall along the salt. moves out to the right creates this
85:15 and decline and leads to generation of normal fault in this, in this
85:23 with assault mode here with continued This moves out to the right,
85:29 get a whole series of rollovers and regional faults developing in this orientation.
85:41 fault systems fault follow form analogous lee now it's the hanging wall that's moving
85:48 inward. So here's a block diagram that. The salt layer here,
85:54 basin, we're dipping faults flowing into salt here as the hanging wall moves
86:00 , it creates this space in here the salt to flow into from below
86:05 from sediments to be deposited here in hanging wall as more and more sediments
86:12 deposited here without loading drives this hanging further and further down dip. Mm
86:22 . So here's an example of a fault system in the gulf of
86:28 So this is north on this South on this side. Mm
86:33 The main regional fault extending down here into the top of the salt here
86:39 younger and younger district normal faults moving section here and here and conjugate collapse
86:47 a clone reforming over the crest of overall rollover structure. So here's um
87:01 interpretive model of how these things evolve . It is is present day and
87:07 here I am restored it to the , minimizing here of this up missing
87:12 to a sub horizontal data here and this football position fixed when I do
87:20 . I create a gap along Can we assume was filled with
87:44 So here's a seismic section from the basin showing the evolution of these
87:50 Series of turtle structures and roll overran here restrict normal for Listrik normal
87:58 The big Bass and we're here here here. So going into the salt
88:03 here. Mhm. In allowing this hanging all packaged to move in the
88:10 dip direction along the basil salt and Listrik Power falls. So many basins
88:23 the sediment catchment areas formed by salt in response to sediment loading. So
88:30 start with a salt layer down begin to deposit sediments locally. On
88:37 of that. That loading leads to of assault and movement of the salt
88:42 the into the pillows. Entire puree that creates more on. Okay,
88:50 de positional space in the overlying sediments more sediments in having a cycle of
88:59 and insult evacuation. Moving up into shallow die appears. No. When
89:07 get these landlocked finished, here's the process can repeat itself. So we
89:12 a lot of assault up here. secondary motivation here leading to loading of
89:17 and evacuation of the salt from the of the mini basin into the into
89:22 dye appears on either side. so that gives us this mini basin
89:31 that's so prominent in the gulf of , where this is a map of
89:35 sea floor in the gulf of Mexico you see all these all these little
89:43 , many basins and catchment areas in bounding salt highs. So here's an
89:57 of any basins of assault on assault off for Louisiana. Un interpreted seismic
90:03 here. Top salt clearly visible there , pretty clearly visible there interpreted salt
90:10 here and then false added to the here showing the sedimentary fix here and
90:17 . Many basins in these locations could to loading of assault and evacuation of
90:23 in the regional down dip direction. . So here's a reconstruction of
90:39 We're starting with an unlocked and assault here with still a feeder too.
90:44 mother salt layer here with deposition on of that. The salt body is
90:52 . The feeder here is pinched off the salt body moves down, dip
90:59 onto the eventually onto the sea floor with progressive loading of sediment catching of
91:08 . You form multiple many bases on of the salt by leading to more
91:13 of the salt and more down dip more down dip extension of the salt
91:23 . So here's an example of zoomed on a particular mini basin above locked
91:28 assault. So we have salt here here. This is an un interpreted
91:34 . This is the same section So we see salt body here,
91:41 salt here, normal faults sowing into sault body here, wells here and
91:50 and here and another small salt body here in the update position so as
91:57 sediments have been deposited here, they the salt at this location and forced
92:02 up into these two adjacent salt wow ! With progressive sedimentation, you
92:09 normal, normal faults along the flanks assault. More and more sediments are
92:15 here and the salt is progressively evacuated these adjacent salt highs. Mm
92:26 Okay. And and that gives you very continuous salt sheets within the mini
92:35 . This is a section between the and macaroni fields in the gulf of
92:41 were flattened on a date in You see all the size of horizons
92:45 representing representing different reservoir she appears and how they're they're nicely continuous across the
92:52 basin. They thicken in the core the mini basin in the center of
92:57 Mini, based on the keel on mini basin and then thin up onto
93:01 flanks of the salt in both Here's a schematic line drawing showing that
93:12 soul body here, somebody here many in between the sediments are deposited
93:19 They drive the salt out here, the salt out here cause it to
93:25 or well that this position and leading relatively continuous sheets deposited in the yellow
93:33 of the schematic section here. mm hmm. So one of some
93:44 the important things about this is that get these sand sheets within individual mini
93:48 basins, but the sand sheets are combination of amalgamated in layered sand sheets
93:59 combined fault and strata, graphic pinch traveling and subsidize. Mikhail shells within
94:05 sands result in strata graphic compartmentalization and in vertical permeability increase in vertical compartmentalization
94:16 you go up and down section, that salt body. So if you
94:21 back and although we have all these resource here pairs, there's a lot
94:31 sub seismic secondary shale draping. Then , that leads to both lateral and
94:38 compartmentalization within each one of these sand . So it's not on a production
94:43 scale is not good pressure communication, this being an overall really nice unity
94:53 . All right, so here's here's interpretation of this section, showing some
95:00 that, some of those geometries. , we have individual sand sheets shown
95:06 in yellow, but then Shelly layers here in the browner colors, resulting
95:13 both vertical and lateral compartmentalization of those continue with sand sheets, mm
95:27 And here we see the thinning of onto the flanks. So, if
95:32 zoom in here and look at this loop, that's only in the salt
95:37 , that single loop consists of the of sand and shell beds with that
95:44 in the northeast direction upon to the flank. Mhm. And with shales
95:51 those beds that limit the vertical communication each of those beds. Okay,
96:02 many basins and related fault geometry. here's a block diagram showing the salt
96:11 up section and the down dip direction , Up to 60 scarf here on
96:17 of that salt. We get the catchment areas that for many basins or
96:22 false bounding both the up dip and normal and the down dip side of
96:27 many basins as these catch sediment, sediments and load the underlying salt.
96:34 becomes a never ending cycle of salt , catching sediment and thickening of the
96:42 in the Mini basin here. All , Okay. And then the 6'
96:53 at the toe of the slope. get these overturned beds that we think
96:57 from this, the tank tread conveyor model of salt advanced, so the
97:02 are deposited on top of the salt here and as the salt moves down
97:08 , these beds are rotated, entering position of the total the slope.
97:19 , so you let's take a break take a few minutes you have this
97:23 an exercise. You know, assault , consult here with personally interpreted
97:32 showing them the the bright lines green, red, yellow,
97:37 brown. So what I want you do is extend these horizons onto the
97:43 of the Mini basin, interpret the of assault on the main basin here
97:50 over here. Don't interpret the base the salt here and extend it down
97:56 here and see how the the de access of this basin has kind of
98:04 back and forth as a function of and the salt evacuation. Let's
98:15 let's take Take 15 minutes. We'll a take a break. Work on
98:23 In 15 minutes, we'll come back discuss what the, what the space
98:29 like. So I left you with again. It's hard to interpret exactly
98:37 this, you know, on the of seismic. Um, but what
98:45 , what I wanted you to come with with something like this, where
98:48 from the top of the salt body along like this and then down
98:55 forming the Locusts and all the pitch around here. The .3 Mhz Horizon
99:04 across here. Let me get into set of constant normal falls over the
99:09 of this other salt body and the body here is not as well defined
99:15 here. You have the top of salt here and a basalt extending about
99:22 . The basalt is a little bit . You might have put the basalt
99:28 along here along this higher loop and little culmination of salt in here,
99:33 pillar of salt in here that all normal faults then right into the
99:43 The other horizons extend over like this like this, it was important to
99:49 this steeping increase in the dip up to the final assault from the 0.8
99:55 . A 0.88 M. A And then the point the three main
100:04 extends along like this, going up the normal falls here In the 3.8
100:09 . A Horizon extends along here. you try to follow the base of
100:15 to connect these into one salt you can't really do it because there
100:22 no salt. The salt body, top and the base pinch out coming
100:27 deep here. So you get a here and up along the base of
100:34 salt here to the connecting of the . So the shotgun over here.
100:40 on here, this salt has been evacuated to form a well now and
100:47 looking at the risk, the relative things within here, mm hmm.
100:52 the earliest phase of their position In in May, the basin thick was
100:58 here on the on the left hand going up to 3 to 3.8
101:04 A. The deposition of thick was here on the other flank of the
101:10 And then coming up again to the M. A. The deposition of
101:16 was over here on the basin, the the deposition of thick on the
101:21 kind of rock and rolls back and between the two different flags of the
101:29 . So here's here's a 1 - interpretation and restoration of that. So
101:34 the there's the .3 .5.8-3 in the M. A. Horizons. Somebody
101:43 , somebody here welded there mm hmm now to the .5 and eight
101:52 If I pull that up to a data, mm hmm. That comes
101:56 to here. These These players come . You see the relative thick here
102:02 here thinning on for this salt This stays pinned in place and you
102:09 the volume of salt to his present between on what is now the top
102:15 the basalt. So this part of salt body is greatly thickened in this
102:22 stuff. Going to the next race restoration step at three a.m. A.
102:29 going to pull this guy up to horizontal data so he's built up
102:35 This this comes up correspondingly the thick the basin now is located over here
102:41 this salt body. Pulling this pulls the top of the salt up
102:47 from further away from the base of salt here, creating the thicker salt
102:53 here along what is now well, doing final restoration, Final Restoration Step
103:02 3.8 M. A. Pulling this up to war zone. It gives
103:07 this geometry where we've got a fairly base and thickness with a depot center
103:14 the middle. We have greatly expanded difference between the top salt and
103:21 creating a relatively thick salt layer in and then the the final step pulling
103:35 top of the salt up to a horizontal data. Um you pull this
103:42 if you leave the if you pin at the two ends of the
103:48 When you pull this up to you extend these two blocks apart from
103:53 other and create space for what was the feeder dike into the salt body
104:02 . So all that comes from this . Yeah. Are there any comments
104:10 questions on that? Did you did get something more or less resembling that
104:15 not? I see like like Yeah. Yeah. This is um
104:27 it's important to get the concept. hard to do it on this side
104:31 section because it's just so reduced. if you get the if you get
104:40 concepts, we're good with that. . Okay. So um c format
104:53 of Mexico again, looking at some the identifying some of the sub
104:58 And in the post slope discovery. , cascadia, Tiber up here,
105:08 Nansen Shannon over here. All lucius and spartacus over here. Mm
105:16 . And so we look at So, those are formed by um
105:24 a lot from his soul bodies like where um we have somebody's here in
105:33 many basics in between many basins that deposited on salt bodies here and over
105:41 is they were deposited the salt was up into these the shallow and see
105:49 nap horizons here, but then form ultimate Topsfield or the salt basins.
105:56 very complex salt geometries and complex fault is related to the salt. So
106:09 details on some of these. They're within the meeting basin province south of
106:15 in mark depths of 4000 ft what produced from lower to middle Miocene
106:21 the primary mini basins Under a 10 15,000 ft thick salt canopy. The
106:30 Polo structure priests from Pleistocene sediments in secondary mini basins along the flanks of
106:35 salt canopy. All of these are in upturned basins along the flanks of
106:41 many basins trapped against the soul. geochemist suggests they were sourced from late
106:49 source rocks, mm hmm. And into the traps probably occurred along the
106:56 and secondary weld in the centers of so here's here's the K two
107:07 the locked in a salt layer that these guys down here reservoir seal horizons
107:14 and here, upturned against the salt here, upturn against a soft link
107:21 And overlaying by this 10 to 15,000 thick salt layer, with additional younger
107:28 basins forming on top of these salt , with additional potential reservoir shell pairs
107:35 there and then along the lines in here where we have wills between
107:45 different salt bodies. So initially we one salt body feed up here forming
107:52 a canopy here, another salt body off here, another salt body being
107:58 somewhere off here And as these grow migrate laterally, they merge and coalesce
108:03 form one continuous assault sheet of shallowing and the two green and red lines
108:15 here represent where in the middle of salt sheets we often find sedimentary rocks
108:23 sediments that represented in this case the roof of this Tabular assault body before
108:32 two salt bodies merged. All so just a simplified example of this
108:45 canopy system. The canopy up sediments underlying it here. Based on
108:55 salt here, these represent multiple seismic factory fractions from from the complex salt
109:10 within the salt body. They're not actual base of the salt. The
109:13 of the salt as shown here and well defined by the sediment terminations and
109:21 overlap. In here here we see relatively well imaged stock fed this
109:30 Mhm. Here's the line drawing interpretation that. The main salt body
109:35 You can see these artifacts here um the salt body, these guys are
109:46 , deep in the section. You these sediments coming and turning up steeply
109:51 the salt flanks on this side and this side as well, and then
109:56 truncated by and conformity that comes along . Mm hmm. And in trunk
110:04 these upturned does and subsequent sedimentation provides reservoir sealed pairs up here in this
110:12 part of the basin. Again, capped and trapped by the salt on
110:17 of the songs here. Okay, , shale tectonics. Um So to
110:31 sale tectonics with Shaler mud die appears very highly over. Pressured shale mud
110:40 appears geometrically can remember can resemble salt appears. Um and there's distinguished primarily
110:47 the known absence of salt from the geometrically they can resemble toe thrust In
110:55 in some cases they are distinguished from thrust by the three seismic data.
111:01 shale is most mobile, went over at depths of about 10,000 ft.
111:07 watering leads to rapid reduction in the mobility. Reburial may increase that mobility
111:17 , internal processes such as release of through die genesis spectacle, light clay
111:24 generation of hydrocarbons increases the mobility and deductibility of the shale. Mm
111:30 But they only increase the volume by few percent. So they're minor contributing
111:36 to these. She'll die appears in tectonics and so she'll deformation is more
111:46 during major over pressuring events. And so here are some mud diet
111:56 made from mud die appears for offshore . We see well defined thrust on
112:02 part of the section and then more diabetes type structures in here and and
112:09 over here a regional field ecole mont at about this level where all these
112:16 soul into and this regional shell Tacoma serves as the source layer for these
112:26 month. I appears here's some mud from onshore Venezuela and these actually
112:37 So you can find these mud die in out tropp with primarily shale in
112:45 mixture of different sized sediments, different cobbles in there in a in a
112:52 , oh, debris flow, light , hmm. And here's a seismic
113:01 and interpretation of that. So down , deep in the section we have
113:07 overpressure, overpressure shales that then feed into these die appears here and
113:15 See you here in here. And some places these lead to mhm mud
113:23 monday appears coming up to the surface we see these kinds of features.
113:33 right, here's a nice example of appears from the Zagros Mountains in Iran
113:40 seismic section. You see the money appear coming up here and you see
113:45 got this kind of christmas tree geometry it where mm hmm. It initially
113:52 up and then float out within your here was continued to be buried and
113:59 out, float out again here and was reburied foot up again here and
114:05 . It was reburied float up again and here by finally generating this
114:10 My volcano. So the these things have this seismic white hot zone and
114:20 of a christmas tree geometry that's generated subsequent by continued burial of these things
114:27 sequential mud die appears and extrusion on I appears near the sea floor.
114:36 right, so salt versus shale The salt mobility is a fundamental property
114:46 to the behavior of the salt and at over burdens of a few 1000
114:53 . The salt is primarily. light and has a constant density and
114:57 viscosity of 10, and 19 The salt mobility is limited by evacuations
115:06 well, they're touchdowns in the sink and rafts. Fault related flow is
115:11 . Die appears are common locked in sheets form large canopies and naps.
115:19 salt tectonics are usually confined to one unit and salt moves out slow rates
115:26 large distances. Shale is most mobile overpressure accepts About 10,000 ft or
115:35 So these originated much greater depth than salt structures. The shale is variable
115:43 composition and flow is related to over effects. It's the shell flow is
115:51 on de watering. The dye appears stop rising once once the de watering
115:58 . The episodic flow results from successive watering and burial and reburial events.
116:09 related flow is common but occurs only overburden approaching 10,000 ft. Die appears
116:15 common, but complete evacuation is uncommon the massive because of the massive deepwater
116:21 of death. Mm minor field tongues common. They may affect multiple horizons
116:28 they are buried to subsequent deaths and moves over short distances at relatively high
116:35 in geologic time. So, one of the examples, we
116:45 she'll die appears quote unquote comes from Nigerian toe thrust. So this is
116:53 location map. The *** delta shelf here with all the onshore and
116:57 fields and to throw stuff here on abyssal plain. So here's a seismic
117:10 of these. So thrust or die and you see there, they're big
117:18 zones are steeply dipping there, um symmetric in the seem to be related
117:31 this massive mother highly overpressure shale layer this region. Now, as we
117:39 we've obtained better and better seismic of , what we see is that these
117:48 really these are really detachment falls with fault characteristics with the detachment layer down
117:58 at the top of the over pressured leading to detachment folds and faults,
118:04 folds up here. So they're not shale die appears there really. But
118:10 thrust detachment forms. So here's an of so for example, from north
118:23 Borneo and here we have a number structures that were initially interpreted as Die
118:30 . Number here 1, 2, , 4 and five. With improved
118:35 data, we realized that these are that catastrophe from toe thrust that were
118:44 interpreted as shale die appears or mobile , but they're really just typical trust
118:51 attachment films. Okay, so summary this section, Physical properties of
119:03 The salt is denser than sediments at than one km depth. It's less
119:09 than sediments And that's greater than one . The factors influencing salt movement are
119:18 , inversion buoyancy. There's nothing from , from the change in density of
119:25 salt highway adhere the second greatest factors differential loading the thickness of the density
119:38 the overlying sediments loading the salt and it to be extremely in other
119:44 extension and contraction, and once the reaches and you're darn near near mud
119:53 , near sea bottom from gravity spreading an important process. Autonomous assault structures
120:01 these rollers pillars, die appears wells turtles and these increase on this.
120:12 creates the increasing vertical relief of these types of structures. So they're all
120:18 related rollers, pillars and die It's just that the vertical relief becomes
120:23 , much greater as you go from to die appears wells or where the
120:30 was president but now has been completely by loading right turtle structures are where
120:37 de positional center on top of salt been inverted by complete evacuation of the
120:44 . True. We have to talk an assault structure mechanisms active pierce
120:51 Where of assault moves vertically upward, hmm, piercing the overlying sediments and
120:59 di appears where the top of the remains at a constant rate and the
121:05 are deposited and subside along the flanks the salt mega flaps are one consequence
121:17 this town building and they represent sediments have been rotated up to near vertical
121:25 along the flank assault body Sub We also commonly see these overturned 4th
121:34 . There are a consequence of this tread conveyor belt type. Advance of
121:39 salt bodies reactive dye appears are those form where the salt fills gaps formed
121:49 extension. So these develop where we the go overlying beds are pulled apart
121:57 extension in the shallow section there extended conjugate normal faults. You get nice
122:03 in the deep section. You get reactive dye appears, filling in the
122:07 formed by that extension. Right. we get these locked in assault structures
122:13 sheets that are formed by extrusion of . So you get the that the
122:21 type teardrop shaped die appears and then of those die appears into one continuous
122:28 basement faults influence salt tectonics. Salt detachments are critical for where all these
122:37 faults. These normal Listrik faults And basic bounding falls. So 1 2
122:44 gulf of Mexico many basins or we all these little pop market mini basin
122:50 centers formed on top of the Whether it's off topic, finish or
122:54 in this and then shale tectonics, get vertical structures that have a superficial
123:01 to salt tectonics. They are distinguished by but knowing that there's no salt
123:08 in the basin. Mm hmm. by improved seismic data. We're seeing
123:16 more and more of these mud die . Are actually deep water tub
123:22 True. Alright. So we're done this section. Are there any comments
123:32 questions on what we've covered in this on assault and shale tectonics.
123:39 okay, okay, the next section on detachment faulting. I mean full
123:51 belts. So a big change in . We can, I think we
123:58 do it in an hour and still it. It's 5:00. So why
124:03 we take a, take a break . Take a 10 minute break And
124:07 start again promptly at 4:00 PMclock and change gears and talk about thrust
124:14 It's going to be an introduction to introduction to full and thrust belts.
124:20 the next several sessions, we'll look different parts of fold and thrust
124:24 Today, we'll look at an introduction the simplest type of full thrust related
124:31 fault. Ben were called fault. falls. Okay. Is this slide
124:59 up to court scheduled slide. Yes. Yeah, I had trouble
125:04 mind. So I wasn't sure if was showing. So today we'll talk
125:08 in the introduction of full thrust belt fault Ben folds. And then the
125:14 three sessions, we'll talk about different of full thrust belt structures and full
125:19 belt current hydrocarbon occurrences. So there two different types of compression all
125:29 these thin skin falling full trust belt and thick skin for them. Full
125:37 structures, thick skinned like the US structures, son. So these are
125:44 of two and members that we'll talk separately. Mm hmm. The thin
125:49 , um, have low angle detachments or near the top basement. We
125:57 them in conversion margins and passive Mm hmm. Tothe for us.
126:03 all have the same basic geometric They both follow critical table theory that
126:09 talk about in a second. And all follow this team of balancing concepts
126:15 basic building blocks required for balancing in basement. Basic building blocks for what
126:21 talk about fault, handfuls, fault . Full detachment falls in duplexes.
126:29 each of these key major thrusts are in the sink lines. The seismic
126:34 is inherently poor because these are onshore because these have steep dips. That
126:41 of things contributes to very poor seismic . In part because of that poor
126:48 any cross sections must be balanced and a ble. Because of that
126:56 The hanging role and the football cutoffs to match and the ramps and flats
127:02 to manage well. We've talked about that thrust faults conceal. Look at
127:07 examples of that, right? And we'll talk about the third dimension strike
127:13 in the hydrocarbon. Fresh areas that critically important to the amount of hydrocarbons
127:20 these things can hold. And then , we'll talk about football traps.
127:25 have to be unique saddle shapes in feature associated with them that can that
127:30 be used to identify where we have traps. So our favorite block
127:40 the Anderson Ian fault types, more theory, reverse faults, sigma,
127:46 shh max is horizontal sigma three DZ the minimum stress. And that's that's
128:02 . So here's a global location map the red dots showing the locations of
128:08 the major under explored phone belts with hydrocarbon potential. Um Gulf of Mexico
128:17 , Colombia, Falklands, east coast Africa and then all through the
128:27 um Iran Iraq chain through here and lastly deep waterfall belts in the Northwest
128:36 Neo and Iran. Not not Iran . All right, alright,
128:46 critical paper theory is the first order on full thrust belt structures and the
128:53 is that full thrust belts form wedges to uh snow in front of a
129:01 or stand in front of a The angle of the wedge is proportional
129:07 the friction at the base, the of the base of the wage and
129:15 proportional to the fluid pressure in the and the strength of the wedge.
129:22 ? The practical implications of this or already have salt based compression all structures
129:28 have a low critical taper angle, have a weak Tacoma, high fluid
129:34 folds and thrust with multiple versions is and thrust that are discontinuing so long
129:40 in more die appear IQ like structures you have shale based compression structures.
129:46 have a higher taper angle, take hormones folds and thrust verge consistently
129:53 the basin towards the foreman back thrust rare and folds and thrusts are relatively
129:59 long strike. Um In this schematic diagram we have a low critical paper
130:09 with a very weak to coma because that week Tacoma. All right,
130:16 sigma sigma three sigma, one is , sigma three is vertical. In
130:22 conjugate reverse faults that are associated with are relatively symmetric and that gives you
130:29 symmetric fault pattern that leads to faults folds verging both in the base in
130:36 forward direction and in the hinterland direction you increase that base with the common
130:44 , you get a greater critical taper created critical taper rotates um sigma three
130:53 sigma one. So they're more oblique the basil to Coleman. And that
130:58 in a set of conjugate faults where the set the verges towards the basin
131:07 I mean towards the fallen towards the is favored and you get um more
131:15 versions of falls and thrust in the propagation direction towards the basin and towards
131:22 fallen away from the hinterland. Okay, okay. So um occurrence
131:41 regional geometry, convergent margin fold belts the indian trend accretion eri prisons,
131:50 plate, full belts like the deepwater rust belts all follow the same fundamental
131:57 model. This critically tapered wedge model but the shape of the wedge is
132:04 to the strength of the Tacoma at base of the wedge. No,
132:10 we see this both in classic fallen thrust belts that we see on shore
132:16 we see it in the deep water thrust belts that we see at the
132:22 slopes in many de positional systems, all follow the same basic premise is
132:27 same basic rules. Okay, so stronger shell based congressional structures are associated
132:40 these features. A high critical taper and thrust first consistently towards the basin
132:45 the foreign land. The folds and are relatively continuous long strike. And
132:52 are typical of the Canadian us over soviet dictator Taiwan full thrust belts.
132:59 here's a typical typical cross section from Canadian full thrust belt. No,
133:05 is C the thrust influence all virg the right. They all verge towards
133:11 towards the forum. But there are back thrust in here. And that's
133:16 you have a shale based detachment and high critical taper to the whole
133:27 Okay. Where we have weak salt or highly over pressured compression. Als
133:35 compression structures associated with the load critical symmetric folds, folds and thrust verging
133:42 both directions but discontinuous folds and thrust strike in symmetric detachment fold structures.
133:49 these are the characteristics that we see deep water Nigeria Perdido, where we're
133:54 assault attachment. Mexican ridges and compensable where we have a salt attachment Angola
134:00 assault attachment in Pakistan, where you a salt based attachment. Thank
134:05 And here's here's an example from ah mexican bridges just offshore of Mexico,
134:14 hmm. See attachment located this Come on and it's it's a salt
134:23 attachment. The folds are symmetric. urged both towards the hinterland and towards
134:30 basin. And they're very discontinuous in out of the plane along strike.
134:37 this kind of symmetric full thrust belt tells you that you're in a section
134:43 highly over pressured sale or assault President. This kind of geometry tells
134:53 immediately. You're in a very strong Tacoma based system. Mm hmm.
135:02 shield attachment. Not not assault Okay, right. Okay.
135:13 um Mhm. Some of the assumptions we're making our interpretations are that The
135:23 and shortening is almost exclusively a 2D strain. So when you make these
135:28 sections, all the shortening and deformation in the plane of the section and
135:34 little occurs out of the plane section to the paper here, bed lengths
135:40 thicknesses remained constant during deformation. The for that are assault and overpressure sales
135:48 do not necessarily maintain constant length and , but they do maintain cross continent
135:54 sectional area thrust. Have a flat geometry. Um They ramp up
136:03 in the transport direction. Mm The styles shown in cross section reflect those
136:10 you actually see in maps and The implications of these fundamentals or that
136:19 deformed beds must be restored Hubble to original sub horizontal data. The original
136:25 lengths must be the same for all deformed beds. And um caveat to
136:32 . Is that a balance section is correct, but it is only one
136:36 many possible interpretations. And then I'm showing how it calculates shortening short
136:45 , remember is calculated as the difference length divided by the original length.
136:51 it's the final length minus the original divided by the original length. So
136:57 like this section of the brooks the final night Is 142 km,
137:03 km. The original length that you from a restoration is 215 km.
137:10 the shortening of the Brooks range then this 140 minus 2, 15,
137:18 divided by the original length to Which is a negative 35%. And
137:25 the shortening is a contraction of the length is less than the original length
137:31 this shortening percentage has a negative sign front of it. Right? Um
137:43 here's an example of a balanced cross on the bottom and the seismic for
137:50 Across the top here. And you you've got good reflections out here in
137:55 in the four line. When you into these more complex zones here,
138:00 seismic quality is very poor. When you get into these large over
138:05 , like the Brazos thrust here, get velocity inversions and basically seismic will
138:12 out sounds so because the seismic is poor, it's important that any interpretation
138:19 this, the balance double, so at least has a chance of being
138:24 of the correct interpretations. Mhm. . So here's here's an example from
138:33 Canadian rockies. You see everything verging the foreland. A series of wedges
138:40 here. Thrust hero version towards the , The final length. The present
138:47 length of this section is 17 If I restore this, if I
138:54 and restore all of this. All , The restored length is 39
139:01 So my final like is 17 My initial length is 39 km.
139:07 my take a minute and calculate the for this -0.5650. That's a red
139:35 man. Could you repeat what you said? -0.564 -22 x 39.
139:44 . And what percentage does that work to? Yeah, 56%.
139:59 So that that was right. The is this final length minus the initial
140:05 Divided by the final length or a 56%. And these numbers are sort
140:10 typical of what we see for onshore thrust belts. shortenings of sort of
140:17 or 60%. Not not hundreds of . No marge, not hundreds of
140:26 of translation, sort of tens of and tens of percents. Okay.
140:36 now, what I'm showing here are seismic section from the bolivian full thrust
140:46 . And the heavy black lines represent data constraints that we have from good
140:53 data and from well controlled everything else the middle here and in here,
140:59 pretty complex flee to form and it's well constrained by the surface data or
141:05 subsurface data. Yeah, what that is we can make five different balanced
141:12 sections of this single cross section We have what's called a duplex here
141:21 four long thin slices instead of fourth thin slices. We could have three
141:28 thick slices. We could have two as shown here. Three unequal different
141:36 or four thick thick slices shown So all of these things are balanced
141:42 and restore a ble. All And when you make a balanced interpretation
141:48 something like this, we need to cautious that that interpretation is potentially
141:54 but it's not unique. It's only of many possible interpretations. True.
142:07 . Alright. And to get a section, we have to relate the
142:12 shapes and the fault shapes and recognize there are dependent. All right.
142:17 normal faults. We talked about these Now for reverse faults, we're going
142:22 talk about these relationships where the thrust betting parallel. You only get lateral
142:29 of the hanging wall where the thrust to cut up section is the only
142:34 that you begin to get any vertical of those beds. Now, when
142:46 when we do a restoration on there 2 2 parts of the restoration.
142:53 me if I come back to The There's a vertical line in the
142:59 . outside the zone of defamation. called a pin line and that's kind
143:04 the anchor that we under form or everything to no back of the section
143:12 is represented by a vertical line that's the loose line. When we do
143:18 restoration, that loose line has to vertical as well. If all the
143:23 lengths in all these units are the , then both the pin line in
143:28 loose line are vertical. And that's that's a requirement for a balanced
143:38 So, when we look at get sections like this, quote unquote balance
143:45 like this from their their complex So, it's a complex problem.
143:51 if I do a restoration of the loose line in the back here
143:56 not vertical. The shallower beds are and the deeper beds. So that's
144:02 me that this is not a properly section. Similarly, here's another example
144:08 where if I restore this section, loose line back here has an inclination
144:14 it. Shown here. That's telling in this case, the shallower beds
144:19 too short. We have to make modifications to the interpretation to lengthen the
144:26 of these shallower beds relative to these beds. Um And here's here's another
144:38 where the loose line is not vertical in the restored state. So here's
144:46 deformed section. Here's my restoration of . The loose line here now is
144:53 quite jagged. It's quite non vertical on the the restored session. And
145:00 telling me that this is not a balanced section. That these the section
145:06 to be reinterpreted so that the bed are all equal within the section.
145:17 , this illustrates what's referred to as bow and arrow role. We're looking
145:22 a map view of Canadian full of thrust. She goes from a tip
145:29 to a maximum displacement here to a here. And the maximum displacement along
145:37 thrust occurs in basically the middle of salient here and so from this geometry
145:46 the thrust, this line connecting the lines and the thrust in the actual
145:53 here resembles it's analogous to a bow arrow. And as we call
145:58 the bolero role that the maximum displacement more or less in the middle of
146:03 thrust salient in the middle of the field. And this is similar to
146:10 we talked about in the QA QC about the displacement generally being the greatest
146:17 the middle of the fall. now we have different geometric full types
146:25 this this block diagram illustrates the full that we use. So we have
146:33 fold axis or the hinge line here represents the the line that if you
146:40 that through space would generate. This . The Crestor hinge here. one
146:48 here, one of them here, hint zone here at the sink Lionel
146:53 of the fold. The wavelength of fold is this dimension? The amplitude
147:00 the falls. Is this dementia In middle of the fold, you have
147:04 inflection point or an inflection line where sense of curvature changes along the
147:13 Where this hinge line is not perfectly . It's a boat like this.
147:21 this now is defines a non cylindrical . So I cannot generate this form
147:28 this single line. In this case can generate this phone by moving that
147:33 line through space. In this case can't do that. That's the difference
147:37 a non cylindrical fall in a cylindrical . The actual surface and the actual
147:45 are basically the by sector of the the soul. Okay, so this
147:58 different full types based on on dip cigars. So I have the top
148:10 the folded bed here, the base a folded bed here and then these
148:15 within the full connect areas of sides points of equal dip on the two
148:22 of the folded layer. And this . This one where we have a
148:29 strata, graphic thickness, this thickness to the beds. It's constant all
148:34 way through the fold. This is parallel form. And this is the
148:38 common kind of fold that we have deal with. Sure a similar fold
148:44 one that's shaped like this where the thickness is not constant as you go
148:50 the, As you go around the . This is what's called a 10fold
149:00 the the limbs are approximated by straight surfaces with just a sharp angular change
149:10 kink fold at the hinge of the . Now this also maintains the constant
149:16 graphic thickness similar to this. And it's it's mathematically easier to do
149:23 lot of calculations with this king full rather than with his parallel fel
149:29 And so you'll see a lot of you still have a lot of restorations
149:36 interpretations of food that are based on skin full geometry, even though they're
149:41 fools in real life, are in parallel fel geometry. And then
149:48 we have these concentric fools where you a constant strata, graphic fitness.
149:54 But now you also have a constant of curvature along the whole fold.
150:06 typically in geology we're dealing with flexible folding where these beds as they
150:14 slide past each other in that's represented by on the ends of these folded
150:22 being different on the ends of the along the bed. You often get
150:28 sides on the bedding surfaces, indicating this relative displacement has occurred between the
150:34 lands. Okay, now we also internal layer deformation within the folds.
150:47 if I take a series of layers this and I fold them into this
150:52 and I keep the bed lengths So I don't have the flesh will
150:57 folding. Mhm. Now I'm going get extension in the outer arc of
151:02 fold and contraction in the inner arc the fold with a neutral surface.
151:08 surface of no finite longitudinal strain through middle of the floor that separates the
151:15 areas of extension from the underlying areas contraction. Um As a full
151:23 this neutral surface moves deeper into the . And so you get over printing
151:29 the original contractual structures by the younger of structures formed as the fold is
151:39 and that neutral surface moves deeper into fold. Okay, so here's here's
151:51 example of a concentric form in on . And you can see the layers
152:00 and here and here, well defined here through here. They're all pretty
152:08 thickness. There are not exactly thickness you go through the fold, you
152:13 some thickening here in the in the of the fold, but it's approximately
152:20 as you go through the whole fold we see both types of folds in
152:30 crop. Often combined. So here the core of this form, I
152:36 these straight fold limbs with an angular geometry at the hinge. And so
152:42 got a kink fold here in the of the fold. If I go
152:47 in the shallow reception in the fold here on these beds have a more
152:54 configuration to the hinge, Indira. hear I have a concentric full different
153:01 the came forward that I have in core of the structure and this,
153:05 kind of variation of NFL is just what we see in geology.
153:14 here's a nice example of a king from seismic data. This comes from
153:18 potato foam belt. You see very limbs here here and here with sharp
153:27 formed here in the sin climb in in the antique line. So this
153:31 a really nice example of the king geometry. And this is this is
153:40 Matthew of the king fold on. see the birds training like this betting
153:48 dipping to the south here into the here. So it's to be in
153:52 core of the structure. So we're at a sin klein overall with a
153:57 straight limb here. A sharp pinch and a very straight limb here.
154:03 it's a in Math you were saying king. Full geometry with a typical
154:11 angular hinge here at the hinge and straight lands on the flanks.
154:27 thrust sheets in fluid over pressures. require high fluid over pressures. And
154:34 just a consequence of the geometry panics you take a slab of rock And
154:40 try and push it from one If it's just a try detachment surface
154:47 on the, the friction along the of that surface is greater than the
154:55 strength of the rock. And so , with this kind of geometry,
155:00 crush the rock rather than transport So we need to get these far
155:07 trust that we see, we have reduce this friction along the base of
155:12 thrust, and the easiest way to that. The most common way to
155:16 that is with high food pressure. with the same geometry and all the
155:23 stresses. If I have a high pressure in here, that reduces the
155:28 of stress at the base of the and allows this fresh sheet to move
155:34 being internally crushed. What? so all our compression structures must be
155:50 a ble and this is a cartoon four different types of but inherently restore
155:58 ble interpretations are inherently restore a ble . A duplex structure here, default
156:07 folds here, fault bend folds and a triangle zone here. And
156:14 . And the duplexes where we have thrust slices piling up at a
156:21 flat ramp, flat geometry, fault fold is whether thrust dies out into
156:28 blind trust in a fault bend fold where a fault is formed by movement
156:34 the hanging draw over a flat flat geometry. These four types of
156:41 are all inherently restore a ble. maintained constant bez length, constant bed
156:49 . The football ramps and flats matched hanging wall ramps and flats in.
156:55 slip or fall slip is not fault slip is going to die
157:00 Did you go towards the basin in this model? Hmm. And so
157:08 false slip is not a requirement for restore herbal section. In fact,
157:13 historical sections cannot have constant fox. . Our goal in making interpretations is
157:22 to restoring interpretation. It's too make potentially restore herbal interpretation without necessarily having
157:32 go through the restoration exercise. That is exercise. It's very time consuming
157:39 tedious. So if we can build restore a Ble structures to start
157:46 we can avoid this really tedious exercise the back end of the interpretation.
157:55 , now, when we look at we interpret seismic data, um,
158:01 typically interpret it as shown here on bottom and this is a result of
158:08 I'm just really exciting wipe out sounds we have these duplex structures. We
158:14 have a white predniSONE in this And what that leads us to do
158:20 take a thrust and and ramp it through the middle of the section
158:24 Through the middle of that. No zone fault propagation folds again. This
158:32 limb is a seismic wipe out So we typically take the fault and
158:37 them through the middle of that wipe zone. That's gonna give us unrestored
158:43 interpretation. Fall Ben feld is symmetric so, um, we typically interpreted
158:53 trust version in both directions as a of the sergeant wipeouts sounds. And
158:59 this gives us a non restore a interpretation. Right? If I take
159:05 interpretations and I try and restore All right. I get what's what's
159:12 here is the bottom on the I get all these gaps in our
159:16 within the section that in the restored telling me that this interpretation is
159:23 It's not restore a ble. But want to avoid going through this last
159:29 of the exercise if we can And avoid that, if we can get
159:34 good head start on avoiding that. we avoid avoid these types of
159:42 Okay, alright, now we're going talk about fault related folds and the
159:46 type of those which is a Ben folds. All right.
159:53 So, thrust faults are typically characterized a stair step geometry on the head
160:00 fall flat, flat section that follows very parallel detachment in the incompetent units
160:07 shells and salt evaporates. And then false step up through more competent units
160:15 what are called ramps. So, have this stair step geometry with
160:20 ramps and more flats. Movement of thrust sheet over each ramp produces rule
160:28 santa klein and passive sin klein. are the fault bend folds. And
160:34 was first proposed in 1934 by rich in the whole value decline in the
160:45 . So here's an animation of a man foreman. I'm taking the pain
160:49 is sliding into the right. You as it goes as it goes up
160:57 ramp with increasing displacement. Mhm. sin criminal hinge stays fixed to the
161:07 where the fault cuts up section. hinge in the hanging wall stays fixed
161:14 where the hanging wall section. The wall thrust goes from a flat to
161:22 ramp. Right? This antique Lionel at the front of the fold is
161:28 anchored to this step in the fault where we go from a ramp to
161:33 flat in the football geometry. the dip of the background here is
161:42 the same as the ah dip in fault ramp back here, the crest
161:49 the fold here is sub horizontal. And the dip here is essentially parallel
161:58 the cut off angle of the ramp here. The loose line in the
162:03 of the section is vertical. The line in the front section is
162:08 Mhm. And what else? Oh yeah. So on this section
162:17 the fault where we're following a bedding flat, there's no vertical displacement of
162:22 hanging wall. Similarly up here where following a bedding parallel section of the
162:29 , there's no vertical displacement of the wall. There's vertical displacement. The
162:35 of the hangar wrong. Only where hanging wall moves over this. This
162:40 ramp and here's an example of a bend full from the Canadian rockies,
162:54 ? She either ramp here putting parallel here and the hanging wall beds.
163:01 this geometry parallel to the flat parallel to the ramp here. So
163:06 geometries or or following this challenge that see here, flat and then parallel
163:17 the ramp here. Yeah, here's another example from outcrop where we have
163:30 fault bend full an outcrop. You see the hanging wall rolling over
163:35 Mhm. The flat for the fault located. Mm hmm. This essentially
163:42 bedding plane surface here, the ramp the fault cuts down section here.
163:48 the ramp here is parallel to the in the hanging wall of the
163:59 Here's another small scale example from Yeah, football here, hanging while
164:07 , fault ramp cutting up section here becoming betting parallel along through here.
164:15 we're going from Iran to a flat at the outcrop scale here. Another
164:27 scale example of a fogged and You see the football here, the
164:33 wall here hang naturally inclined, nicely here. Mm hmm. But section
164:39 here, ramp where the fault cuts section and then a flat section to
164:44 fall back in here. Yeah, can see from this section that that
164:55 ramp cuts across a more little section the deformed section, whereas the flats
165:02 in the shales that that bound that grilled session. Okay, here's here's
165:12 example. Football here, hanging on . Four. Coming up through here
165:21 , it's the ramp default is a cutting up section of about here and
165:26 here it goes. Bedding parallel out here. So, another example of
165:32 ramp, flat geometry. No, here's here's another example of this um
165:49 ramp, flat geometry. Tang will football here. The actual fault coming
165:57 here and then going bedding parallel So again we have this ramp,
166:05 geometry to the fault and the beds the hanging wall. First the dips
166:10 the beds are essentially parallel to the of the football ramp. True,
166:20 , so here's an example of a , inclined and full and we're gonna
166:26 it with this king fold geometry because makes things simpler to understand. So
166:33 my football, Here's my hanging The thrust is here, it goes
166:39 a bedding parallel, flat cuts up in the ramp here goes to a
166:44 parallel, flat up here in the . This here in here, I
166:53 a normal strata graphic sequence and there's vertical displacement of the beds in the
166:58 wall over the trailing flat or the flat up here. Between these two
167:08 , you get older over younger budgets , um from the, from the
167:14 of the bags. And this is only area in which you get or
167:18 vertical displacement of the Bennetts on the limb here, the dip of the
167:24 glam is parallel to the dip of ramp. So in the thrust cuts
167:30 section in the direction of transport is here and the actual surfaces. Help
167:44 understand this. These two actual services the trailing edge of the decline in
167:52 But in the hinge of the trailing coin here, these are tied to
167:57 nick points in the ramp. This is tied to where the fall comes
168:01 section. This one is taught to the fault goes back to a petting
168:06 flood situation. So we can use actually playing surfaces to identify where the
168:14 of the fault ramp seller. These leading actual surface locations are tied to
168:23 are tied to the hanging long and are going to move forward with
168:37 Mm hmm. So in terms of geometry, the sin Clennell huge is
168:45 at the leading edge of the hanging ramp here this and a little hinge
168:53 the hanging wall is tied to the edge of the hanging around in the
169:00 wall. This antique Lionel hinges tied the nick point in the in football
169:10 . This actual services tied to where fault begins to cut up section here
169:16 in between these two, the back dip is parallel to the dip of
169:20 ramp. So here we have a of defamation of growth of when his
169:35 controls here with a small displacement. just starting to get the symmetric an
169:42 here at the crest of the structure continued displacement. That an incline grows
169:49 moves out to the left in this . Mhm. Yeah. And then
170:03 characteristics just repeat the other things that talked about. There's no strata,
170:08 repetition here or here. The only , graphic repetition of thickening occurs in
170:15 vicinity of the ramp, where the wall cuts up section and then goes
170:19 onto the football ramp. Alright, we'll go over this again, remember
170:31 in the section, but we'll go it again here and this is to
170:35 a balanced herbal section. The hanging and football ramps and flats half the
170:40 . If the section is balance the ramp remembers where the fault comes
170:45 section. Mhm. And it's typically in the massive sandstone carbonates or mechanical
170:52 within the structure flat is located where fault is bending parallel, is typically
170:58 in the shales and evaporates within the section. So you know, section
171:05 this. If I live to hang the football, I can identify the
171:11 and flats in both sections. Two in the hanging wall on the base
171:18 the hanging wall, the fault is to The green bed all along
171:23 So this is a long one. hanging long flat here, the fault
171:30 up section in the hanging wall. here I've got a small ramp
171:35 The fault is betting parallel in the walls, one of another hanging wall
171:40 and here in the front the fault up section in the hanging ross.
171:45 have a hang broadband here. If looked at the foot long, I
171:50 the same corresponding gramps and flats. this ramp in the blue, in
171:56 hanging wall corresponds corresponds to this the blue or the football. This
172:03 at the base of the blue and hanging wall corresponds to this flat at
172:07 base of the blue and the This ramp between the dark blue and
172:12 green and the hang bro corresponds to ramp in the dark green in the
172:18 . And then this long getting parallel at the base of the green,
172:23 to this flat at the base of green in the football. So if
172:30 unfold this and restore this, all pieces fit back together. That ramp
172:35 on there, that flat fits on . Those two rams fit together in
172:40 flat fits on the flat back Mm hmm. Alright, so now
172:49 here's an example of a full bend from the Appalachians. Football here,
172:55 wall here. Trust here getting criminal . So that's a flat cutting up
173:04 here. So that's a ramp going parallel again down here, deep in
173:08 section, so that's another bedding flat. And overall the fault of
173:17 , the hanging wall dips here, the dips in the ramp here in
173:23 , reading the depths in the four unfold here on, give you a
173:29 off angle equal to the dip of ramp back here. The ensuing we
173:43 here, Football flat, a football and football flat. See all in
173:49 football, in the hanging wall I hanging around d corresponding to this football
174:00 . And then I have a long to basically orange here, hanging off
174:05 see corresponding to the football flat see and extending off the base of the
174:12 . So, this is an example the rams and flats on matched
174:18 Okay, All right, so let's do this one as as an
174:26 I'll take a few minutes and look this. Do the hanging wall ramps
174:30 flats. Match the football ramps and . You don't match 12. We'll
175:22 you one thing, yes. so, well, that's let's talk
175:34 one through. Um but it they do imagine this case. And so
175:41 , um this is the one we talked about where we have in the
175:44 wall here, I have a ramp one here. It corresponds to this
175:50 here. I have a flat here corresponds to this flat. Get the
175:57 between the dark blue and the And then I have a ramp here
176:02 the leading edge of the green that against this football ram in the
176:09 And then from this point on, have a long hanging wall flat parallel
176:15 the base of the green. That to the football flat at the base
176:20 the green in the restored state along . So in this case the ramps
176:26 flags do actually match. Okay, now let's um Here's a similar
176:35 Let's talk about this one. Through hanging wall ramps and flats match in
176:40 this section. No, they don't Right in this one. They don't
177:04 . Okay, so A tricky in one. So here in the hanging
177:12 , we've got one ramp here where fault cuts up section from the green
177:17 the white blue, That gives us hanging rail ramp here and then within
177:22 hanging wall all the way back, interpretive follows the base of the
177:28 So I have one long hanging wall at the base of the green here
177:34 the football. I have two football , one here and one here with
177:42 in between here here in here. here I've got to football ramps In
177:50 football flats that don't match what I in the hanging wall here. Um
178:00 I if I try and restore if I put Mhm this hanging wall
178:08 off against this hanging will cut I'm going to have duplication of the
178:13 in this area. Or conversely, I try and restore it by putting
178:18 screen back against the screen here, going to create a gap and in
178:25 the football cut off and the hanging cut off here in this part of
178:28 section. So the ramps and Don't imagine this is not balance
178:38 Gonna Do one More. Sure why through the rampant flats match in this
179:19 . No there's too many hanging wall and flats. Yeah. Yeah the
179:25 wall is much more complex than the here. So these guys don't don't
179:33 at all. Mhm. So if look at the football first because it's
179:45 . I have a football flat The football ramp here in a second
179:51 flat here in the in the hanging . I just I have hanging little
179:58 here, hang them all around. hang on flat. Excuse me.
180:03 hanging wall ramp here, a little of the hang roll around through here
180:08 the base of the yellow. The hanging wall ramp here between the
180:13 and the orange and then another long wall flat at the base of the
180:19 all through here. So In the the hanging wall here I've got 3g
180:26 three flats in football. I've got ramp into flats. So this is
180:32 restore a ble at all. The and ramps don't match at all in
180:36 interpretation. Very good. Okay. . Um one of the one of
180:46 nice things about this king ban geometry a fault and full model is that
180:52 these angular relationships are geometric really related each other. So the the co
181:01 of this angle theta which is the off angle here is equal to two
181:06 the co second of the angle which is where the data, which
181:12 this cut off angle here minus the tangent of angle beta. Which is
181:18 angle here in this angle gamma. by the half angle of the for
181:28 unfold here, that angle is equal 19 minus beta. Over to.
181:33 so from these geometric relationships with this . Full geometry. If I know
181:42 , if I if I do know geometries, I can use those to
181:47 with all the different cut off angles betting angles need to be in the
181:53 the interpretation. So that's that's one the benefits of this king. Full
181:58 geometry. All right, alright, they're furious modifications of this theme that
182:10 go through here. Now, here a full time unfold where the loose
182:16 here at the back is not Let's just push forward. And this
182:20 what's called shear fault. Man So, within all of these beds
182:25 the hangar, I have bedding pair little sheer increasing as I move upwards
182:31 the detachment. Um This is this commonly appealed to as a style to
182:39 understand and interpretation. And sometimes it's an artifact of not having a balanced
182:45 interpretation with a vertical loose line. , it's this supplies only in special
182:59 . Here's an example of an application that where my thrust faults here coming
183:06 section into a fault. Man cutting up section here again into another
183:10 unfold. And the if I do restoration of this, the hanging wall
183:19 here are much sure than the hanging beds here. Yeah, it's your
183:26 . Unfolding has been invoked as a explanation of that. But in this
183:32 this is a deep water toe thrust . These beds are just there.
183:39 mush, their jello. So they're they're not anything that mechanically can sustain
183:46 kind of bedding parallel share. So chair fault unfolding example. I think
183:55 is an example where the sheer folding is an explanation invoked for an unbalanced
184:04 . Yeah, so this just this talks through this. If you try
184:08 do a restoration of this, you different restorations of the loose line at
184:13 back of the section. Right. you can eliminate that by interpreting these
184:19 detachment folds rather than his fault, fools. Right. Um two other
184:30 in this. The sequence we've talked is where you have one single through
184:38 thrust fault where you go from a to a ram to a flat to
184:42 ramp. And the fault is there to the initial folding, an alternative
184:50 is that the um defaulting can occur initial concentric folding. So here I've
185:02 a concentric fold here in a concentric here formed by a thrust fault
185:08 A thrust fault here. But at point the faults have not propagated and
185:14 up to form a through going Okay with continued deformation. Once those
185:19 up, I get the same geometry as I get here, even though
185:26 the fools in this case predate the going fall. Okay, now we
185:40 do see overturns folk clams at the edge of one of these false
185:47 And this is interpreted to be due the um initial folding of these beds
185:55 the fault propagates through so that you a fault propagation fold. That is
186:01 faltered through in this steepened limbs and out on the flat, giving you
186:06 asymmetric fault bend for geometry. And is an example of that from the
186:18 Ian Powell Valley. And climbing the where you have to hang on the
186:27 edge dipping here, the crest of falcon flew dipping here, but now
186:33 leading edge of the fog unfold is vertical here. I'm sure you have
186:39 steep and geometry where the leading edge the fall pinfall dips much more steeply
186:46 oversleeping relative to the trailing edge of falls. Okay, and this is
186:57 restoration of that type of interpretation. , from the Appalachians hanging out of
187:05 thrust extending through there with um the here, beds in the beds in
187:14 hanging draw paralleling the dip of the here. More complicated because you have
187:20 second unit here. But then the here equals the ramp back here here
187:26 the front of the fraud. We this over, still over steep and
187:30 vertical from land. And if you that, you get you get this
187:40 with that requires betting parallel shear in , in this part of the
187:46 you have no unequal loose line here the back. So the shortening of
187:51 bed here is different than the shortening the rest of the section. So
188:02 here just refines the seismic section across same and decline. And you can
188:07 it really doesn't help you at You see you see the front wall
188:12 , hang on here. Things are continuous parallel to the thrust geometry
188:18 But up here where you have the up the phone and called outcrop.
188:26 . You just you don't have any data to help you constrain Yeah.
188:33 this area. Okay, so here's example of a balance section from deep
188:46 toe thrust in Nigeria. And this something that was published in a pg
188:53 . Mhm. Take a few minutes look at the fault geometries and the
188:58 off geometries along this deeper part of section. And see how they propagate
189:05 into the shallow part of the section ask yourself to the ransom flats.
189:12 . Are the throes consistent on each . Are the folds and faults,
189:17 related. And is this balance double restore a bill or not? So
189:24 a few minutes and then we'll talk through. Okay, in the interest
193:06 time, I'm going to wrap this . This is this is one of
193:11 all time favorite crazy cross sections and positive that you don't need to know
193:17 structural geology to be in a PG editor. If we look at the
193:24 along here, there's all kinds of business going on. If I start
193:29 this, this pop up block have a thrust here. An anesthetic
193:35 here in this. Through going thrust a normal fault deeper in the section
193:43 along some of the faults like this . And like this one the displacement
193:49 decreases with depth. The fault displacement need to be constant, but it
193:55 increase with depth not decrease with And the ramps and flats in the
194:02 them all in the footballs don't match all across these falls. Mm
194:06 Here, we've got moderate angle ramp a high angle ramp. And your
194:12 ramp in the football right? That vertical cut off angle itself is.
194:18 , he is t mechanically impossible. hmm. Here, we've got another
194:25 where the displacement decreases with that large up here, maximum in the middle
194:32 to zero here, as you get to the detachment and again the ramps
194:37 the flats across this guy don't I'm a hyena ramp here versus a
194:44 ramp cut off here. So the and flats don't match. The throws
194:50 not consistent, default and full shapes not related. And the punch line
194:56 this is not possibly balance double and a bubble, is it? So
195:04 it interpreted wrong? Yes, It's interpreted wrong. Mm hmm.
195:11 fact, the whole style of faulting folding here is is different and needs
195:17 be interpreted as on detachment folds that talking about later where you have much
195:23 faulting in a symmetric shape to the . The The interpreter is kind of
195:33 a Canadian style. Mm hmm. thrust built interpretation on this full thrust
195:40 . And it's just it's not correct it's not correct because this is mechanically
195:46 different than what we see in the rockies. Mhm. Okay, so
195:59 summary for full thrust belt structures, looking at a two D strain.
196:05 bed lines and thicknesses remained constant during except for salt and over pressured
196:13 And they're the they don't maintain constant and thickness, but they do maintain
196:18 cross sectional area. No, the beds must be restored. Hubble to
196:24 original sub horizontal data in the original links must be the same for all
196:29 deformed beds. And because of the loose lines in the restored sections
196:35 to be vertical and not inclined for . Penfolds. These are false.
196:45 form is the hanging wall beds ramp over the football. They ramp up
196:50 a transition from a flat to a in the football. Mm hmm.
196:58 the hangar. Old beds are rotated a new tip parallel to the thrust
197:02 ramp. The distance between this between . B. Y. Prime and
197:10 ex prime here are fixed to the of the ramp here in the text
197:17 the bank of Iran. Okay. cut off angles here between this actual
197:24 and this actual surface are tied to nick points in the ramp here and
197:31 . The hanging wall of birds, r constant elevation over the flat parts
197:37 the faults back here, you over here there's no thickening or no
197:42 in vertical elevation over the flat parts the fall and to get the duplication
197:48 the change in vertical realization only where hanging wall steps up over a ramp
197:54 this. And lastly, the hanging ranch and flats must match the football
197:59 and flats. Okay, okay. that's it for this section. That's
198:08 for today. Mm hmm. Any or questions on what we've,
198:15 what we've covered just this afternoon or rest of the day? It's been
198:23 been a lot to swallow today. a lot to cover. Um,
198:27 when are we going to receive the for the midterms? Um, I
198:33 , I'll send them to you in the next class. I haven't looked
198:38 them yet. So I haven't created yet. Um You know,
198:43 If need be you all got through . It looks like you got through
198:46 pretty well. If need be, go over the correct answers at the
198:50 of the next class. Okay. . Have a good week. We'll
198:59 you next weekend. Thank you. you. Bye.
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