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GEOL6350-Advanced Structural Geology - Day5 03-04-2022
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00:00 huh. Let's see. Are you you seeing that title slide?
00:38 Uh huh. All right now, that better? Yes. Okay,
00:48 . Okay, so this is these the main topics we're gonna talk about
00:51 the first half of the afternoon fault folds and detachment folds. But before
00:57 do that, I want to review of the things that came up in
01:00 test. Mhm. Everybody did really on the test. But there are
01:05 couple of things that a lot of struggled with. So I wanted to
01:09 over those again and that was the between the total closure and the total
01:15 height. So I'm showing here that of a cross section of a trap
01:22 up here. Volunteer foreign part of trap. The total closure is the
01:28 between the crest and the deepest spill . So it's that that total vertical
01:36 . The total column height is the between the crest and the oil water
01:42 of the gas water contact to that column height can be a lot less
01:47 the total closure. If you only a little bit of hydrocarbons in
01:51 that total column height is a small of the total closure. And so
01:57 important to understand the difference between these and that's that's what it looks like
02:02 Matthew mhm. In cross section it like this. So I've got the
02:10 here. Structure concerts in black water shown here in the red and then
02:17 total closure is that change in vertical from the crest to the deepest bill
02:24 . So in this case it would from a little above 100 Down to
02:28 550 to spill point here. The column height goes from the crest to
02:35 oil water contact. So that that be a lot less than total
02:40 It's important both in Matthew and cross to recognize the difference between those
02:54 Okay. And the other thing that clear from the test is that the
03:01 of joints and hydraulic fractures and signal . The strike of the joints or
03:06 strike of the hydraulic fracturing is always to Signal one. It's always equal
03:12 the maximum horizontal compressive stress. And The joint strike is perpendicular to the
03:19 . three. Okay, so from like this, from the A budding
03:31 we can tell which are the first joints. So those would be the
03:35 . Ones here, The J. , s. and younger sets terminate
03:39 those. So those are budding relationships us the relative timing in the
03:45 And again the joint strike equals the horizontal stress at the time of joint
03:55 . So this was this was from of the questions probably from these cross
04:02 A budding relationships. Mhm. Is through going one being terminates against
04:10 And see turn against terminates against So those relationships tell you that
04:16 J1 that was the first formed is J. two. That was
04:20 second form in C. S. . Three. That was the third
04:23 the last form true In Sigma one parallel to the strike of each of
04:30 at the time of joint formation. for A. For J. One
04:35 one is east west. For be Jay to signal one was northwest,
04:41 . And first see this joint set . Single one was north south.
04:48 the strike of those joints tell you orientations of Sigma one, the maximum
04:54 compressive stress and the budding relationships. you the relative timing of those
05:05 Thank you. Alright, so I to go on and talk about new
05:09 today. Full thrust belt fault propagation and attachment folds. So we're in
05:22 wheel of fortune of structure diagrams we're up in this quarter looking at
05:26 skinned, trusting both both attached thrusting in here, the different types of
05:32 that form on that. We talked the intro principles to that and
05:37 Ben falls last weekend. And now going to talk about two other types
05:41 folds. The fault propagation falls and falls and the fault propagation folds and
05:53 folds are one of these four basic blocks that's inherently restore a ble these
06:00 propagation folds. Reserve the bed the bed thickness, fault slip is
06:05 constant. And these are these will be restore a bill when you interpret
06:11 terms of these geometries. Okay, here's an example of fault propagation
06:20 seismic data. And what we're talking here. Just blind thrusts. So
06:24 there's the fault bang criminal here, up section here and here's the fold
06:31 the overlying limb here in a steep here and this. This geometry is
06:39 of fault propagation, phones with general land and steve for land. A
06:46 somewhere at projecting into sin clonal access the of the fold. Mhm And
06:55 slip is not constant. It dies as you go up until it eventually
07:00 at the tip of the fault So what we'll talk about a geometric
07:06 and characteristics. This particular model is the self similar model. How do
07:12 get the steepening of the front And a variation on that is something
07:18 Trish here that allows this limb to overturned. And then um we'll talk
07:26 breakthrough models for this fault breaks through fold and transports it similar to a
07:31 and fold. Okay, so here's example, an outcrop. You can
07:39 the general back line here, steve here, sink line here in a
07:46 tip. Just off the base of diagram here. So here's a here's
07:56 animation of how these things work. the fault here cutting up section,
08:02 back Lynn steve forum here with continued . The fault breaks through the limbs
08:11 propagates up higher in the section, fault projects up into the sin clonal
08:17 of the fold. It doesn't break the crust or the form of
08:24 Thanks back here on the trailing part the full. There's no vertical displacement
08:30 the, of the hanging wall. just translated parallel to the bedding,
08:34 , flat in the fall, with cuts up section. That's where the
08:40 um limbs start to be folded. get this channel back limb and steve
08:46 here. I just don't want to that again. So you can see
08:57 that works. So just horizontal translation where the fault cuts up section and
09:18 starting bring the limbs up. You this channel background depina, steep following
09:24 and the fault tip projection to the klein of the leading edge of the
09:35 . Here's another example from outcrop. see the fault here. Benning parallel
09:41 up section here actually appear false And you can see here the the
09:50 line and the foreland rolling over steeper being truncated against the fault. In
09:56 , with the fault slip dying out to zero here and here. Here's
10:06 example from outcrop. And you can the fault tipping out in here,
10:11 Ferrone here. General backlands here. no, no fault breaking through up
10:20 here. Just a steep steep Um This is important because in seismic
10:25 , this will typically be in no zone. This will be a wipe
10:28 zone. And the temptation is always blast the fault through there. Um
10:33 in fact it's the default belongs at base of that known data zone.
10:39 the steep them itself maybe is typically . Let's see here's another example,
10:52 the fault cutting through here back then for them here and now the farm
11:00 actually overturned and the fault actually tips about here and doesn't break through this
11:06 opening section. And here we've got fault propagation fold with a background here
11:12 here, fault down here at the of the section. The back limbs
11:17 both cases are parallel to the parallel the detachment and the forum itself is
11:24 into actually overturned. Okay, here's example of a non scale example from
11:34 Canadian rockies. See the fault here Sinclair anal surface here, Jacqueline
11:42 crest here, steep forlan here and fault tips out about here, it
11:48 break through further up in the section these are characterized by the general back
11:55 and steeped overturned for liver front wind thrust loses slip up section and eventually
12:02 out. The full size is really amount of the slip and these are
12:08 formed and thin bedded layers with both the homogeneous strategy and flexible slip is
12:14 dominant information mechanism of the inter bed here. Yeah, alright, so
12:25 here's a cross section of a fault for showing how these evolve. So
12:32 detachment layer is here, I'm going a small amount of slip here,
12:38 slip to the lower sections here with increasing slip from that fault tip prompt
12:46 up further into the fold, it up into the sink Lionel axis.
12:51 doesn't break through the phone here. . The back limb here is parallel
12:58 the where the fault starts to cut section here. There's no vertical displacement
13:03 the hanging wall here where it's just laterally over the flat. Um This
13:12 actual surface is pinned to where the starts to ramp up section. The
13:18 chronicle actual surface is pinned to where fault tip is in the deeper part
13:24 the fold. And these services A B. Primal move as the fall
13:36 displaced and full and continues to So here we're zooming in on that
13:48 . See the channel back line here four line here, unfolded section
13:54 tip of the fold to the Excuse me here projecting into the sin
13:58 of the fold. Here's a sandbox um detachment layer here at the base
14:08 the tank channel back line here, overturned for them here for propagating up
14:17 section through here. I'm terminating here the top of the pink on generating
14:23 overturned limb. Do we see our in the section, here's an example
14:35 from Taiwan from combination of surface, and subsurface data. See the original
14:43 to hear thrust fault cutting up section . Bedding parallel here, ramping up
14:51 here along this bedding parallel section. is no displacement of that. There's
14:58 vertical displacement on the hang all There's only lateral translation when they cut
15:03 section. Um the vets are carried the ramp. The dip of the
15:10 here is equal to the dip of ramp. The steep forum here,
15:16 hmm projected down to the tip of fault here. The sin klein at
15:22 further full projects down the funds location the tip of the ramp.
15:29 And the actual services here in here not themselves faulted. Okay,
15:44 So this was on a quiz to . I gave you this as a
15:50 last tonight is a handout if you at that. I've got seismic sections
15:56 and here of two different folds with interpret here and here in the at
16:04 King van. Will these be, these be balance double? Will these
16:10 restore a ble um are those faults the correct position? So take a
16:17 and look at that And well, discuss that in a second.
18:13 Okay, okay. So these original are not are not restore herbal interpretations
18:36 on fault propagation falls. You can the general background here steve Ferrone
18:43 Very poor seismic data. Pretty much out in the the temptation is always
18:49 put a fault through the top of middle of that wipe out side.
18:54 you do that, you get an herbal interpretation. With this interpretation,
19:01 can't restore this hanging wall to a horizontal data. I mean if you
19:08 throw the hanging wall through some horizontal , you can't under form the following
19:14 in here. So this is not is not restore a ble. It's
19:18 a good interpretation of a fault propagation . If you push the fall down
19:25 in this section towards the base of wiped out side, you get to
19:29 a ble interpretation where now I can the hanging draw back along that fault
19:35 restore all these beds, both the and and steep them here to a
19:41 horizontal orientation similarly here. Um with hanging wall here, if I put
19:49 fault at the top of the no zones, I can't under form the
19:54 dipping parts of the falls. So fault up here. This is not
19:59 a ble. If I put a down here at the base of the
20:03 , I can under form both the limb and the steeply dipping limbs
20:08 Mm hmm. And this is this valuable from a trapping point of view
20:14 if I move the fall deeper in section here and here and decreases my
20:23 on fault dependent closure too, decrease dependent on false heels to create a
20:29 and increases the amount of disclosure available that trap. Okay now um one
20:44 the, one of the geometric ways get these phones is what's called a
20:51 here fault propagation model. And this where the slip on the thrust is
20:58 dissipated within that forum. Within a deformation zone. Within that form,
21:04 treasure zone is commonly made up of intricate thrust. The forum changes thickness
21:11 and it usually thickens and then thins progressive deformation on the forum, depth
21:17 with progressive deformation from gentlemen dipping to . Mm hmm. And and football's
21:25 can be a common part of this of structure. So this is this
21:31 an example. This animation is an of attrition fault propagation for you see
21:36 thought cutting up section here and within triangle of the triangular zone in front
21:45 the fault here, represented by the red arrows here, mm hmm.
21:52 thickness of the beds has changed. is the zone of pressure deformation and
21:58 the thickness and the dip of the changes within that. So it's a
22:03 different than that first fold unfold model we talked about. President lim
22:09 state constant along the front of the here. Okay, so this is
22:19 example of that where here's my fault full the following now is deformed by
22:27 triangular zone of defamation at the tip the fault propagating upward from the tip
22:32 the fault. And within this try zone we have lots of closely spaced
22:38 zones in there at all, allow deformation to occur within this form and
22:44 the steeped overturned beds in the thinning thickening of the foreman that you see
22:51 begin the back wind is parallel to the fall. The hanging wall back
22:58 is only translated laterally. There's no displacement of the hanging wall here,
23:03 now within the foreland we get this overturned limb and thinning of the women
23:09 this area due to the tri shear and that that trash your deformation can
23:21 in two different ways. one is parallel shear and the other is by
23:29 here where the slip vectors actually differs each other. And this treasure deformation
23:35 what we see dominantly in these fault falls where that forum is deformed by
23:41 spaced cheer planes and and in a orientation like this. Mm hmm.
23:54 . Okay, so now, you , try sure, fault propagation fold
23:57 this. Um Being the forum deformation a function of the the total
24:07 The ratio of the fault propagation to slip and that's not the fault propagation
24:14 , is the measure of how how this tip moves forward relative to the
24:23 . Hi propagation of slip ratio means this fault it propagates pretty much at
24:29 same brain as the slips here. propagation of slip ratio means that this
24:35 has had a much lower rate, the displacement back here. And as
24:41 as the propagation slip ratio decreases. increase the deformation in that forward
24:50 The deformation is also a function of attachment dip in the radius of
24:55 So this dip of this fault and radius of curvature of that Trish.
25:01 zone and right. So now we some examples here of how on that
25:16 genomic changes as a function of the shear parameters. So in the simplest
25:22 like this, I have a plane fault with a planer. Our try
25:27 zone in front emanating from the tip the farm. And you see how
25:32 gives me a general fault propagation folds in here from planner detachment. Planer
25:41 , concentrate your angle and it generates asymmetric fold. Here's the same fold
25:48 strange lips is shown in here and can see how this full of rolls
25:53 like that to give you a fault fold with relatively high strain in the
25:59 of here. Now, if I that same detachment and curve it and
26:06 curve the Trish. Sure zone, can get different geometries generated here.
26:12 now I've got a curve detachment here of the planter detachment in a curve
26:17 your zone here instead of the planer . Your zone here. And this
26:23 me an effect of symmetric fold rather the simple fault propagation fold we have
26:30 . Good. This is an example the same thing with increased displacement and
26:37 smaller. Try sheer some of the here and again. I generated a
26:43 fold with no steep climb here, parallel to the curvature of the fall
26:50 here and a steep form here. a zone of very high strain is
26:56 by the by the strange boxes in . Yeah. All right. And
27:06 gets us to translate it. Fault falls. So if I if I
27:11 that garden variety fault propagation fold and let that fall break through the Sinclair
27:18 the access the incline and from the basically behead this phone and carry it
27:27 onto the onto the football and transport just like a fall tenfold.
27:39 Um so here's here's an example of fault fault propagation fold. This is
27:46 the Canadian rockies, the turn of klein. You see the fault propagation
27:53 here, but now the fault breaks the base of that form and
27:58 it starts to carry it up the giving you a fault and fault propagation
28:05 from this section to this section. the displacement increases from this amount to
28:11 this amount. And with that, that increased displacement again, a tighter
28:18 in the hanging wall here. Also that in both cases we have football's
28:26 here and here and quite prominent here here. And with the with the
28:35 fault propagation for that. We talked this guy. You don't get any
28:42 sim klein in here. Okay, this, this football season, Klein
28:48 indicative of a fault fault propagation Here's another example. This is from
29:01 the nada, the naga thruster. sorry Pakistan. Where the fault propagation
29:07 here, forming the main field Volunteer breaking through the sin clonal axis
29:14 carrying the fault propagation folds of the of the salt. Here's another example
29:26 Taiwan. You see the the football hanging all fault propagation fold here,
29:36 propagation falled undefined by the service steps give me your data here. Service
29:43 again here thought, breaking through the here, coming back down, cutting
29:50 the wells here. Football sink line . And the fault propagation phone now
29:57 fault and carried on up the ramp the fault here, the the back
30:04 dip here is still parallel to the here with the forum now has a
30:09 going through and carrying it on And then here's an example from outcrop
30:19 the Appalachians. You can see the coming over rolling over here.
30:27 more overall structure is a fault propagation . But now this fault has broken
30:34 the opera one towards the monoclonal axis the fold carrying these birds from here
30:42 to hearing, translating that fault propagation up tip along that fault. And
30:58 here's, here's another example from the where the we have an initial fault
31:08 for world that is then carried out this fault that propagates through the
31:13 Lionel axis further. Okay, come , schematic cross section is shown here
31:21 my football. Thank carl detachment here ramps up section. Initially I get
31:28 fault propagation fold here where this fault out into the into a tip in
31:35 senate clonal axis here and then that breaks through putting Colonel here and carries
31:43 initial for propagation fold up onto the parallel flat here and now it's starting
31:50 look very much like a microphone. been full. Yeah, the trailing
31:55 here. The gentleman here is parallel the tip of the ramp here.
32:01 anne klein latches now is translated along bedding parallel. Flat up here in
32:07 any of the part of the Right right now one of the important
32:22 points of these forms is that the this section of the fault, there's
32:29 change in vertical elevation. So the elevation of the trailing edge of the
32:35 here is the same as here. if we project that level across
32:43 father, it connects across the and connects across the fault. And that's
32:53 because this the steep limb is typically poorly imaged on seismic data. And
33:00 if we try and correlate things from hanging wall across the crest of the
33:06 , we really don't know where they out in front of the fold
33:10 And so I can use this regional concept to project where that should be
33:18 front of the fold and in a like shown in this example where the
33:25 levels don't match across the phone. that's telling me that there's an error
33:30 my interpretation. Up here in the of the fold. I need to
33:35 these levels up so that this regional is constant from the angle of that
33:43 the under form in front of the here and that pulling that up,
33:48 the thickness of my this deeper in section. So this thickness would be
33:55 across the fold. We're in this with the unequal regional level. It's
33:59 maintained. Mhm. So this is this is a valuable tool or technique
34:06 constrain what my what my strata graphic are in front of the phone like
34:11 . Rather than trying to force them the crest of the fold. With
34:21 seismic data, we can use an line to do that. So here
34:25 looking at a thrust fold fault crest the fault here. This is
34:33 by curvature now. So this is most deeply dipping part of the
34:39 So with three seismic data, you take an arbitrary size decline like this
34:44 goes around the tip of the fold compounds to the front of comes back
34:49 the front of the fold and carries strategic graffiti here into the football in
34:55 of the thrust fault here. so here's what that looks like in
35:03 section. There's my, there's my level shown here in yellow here.
35:08 am in the hanging wall where that well defined. Here's where I'm going
35:14 the tip of the fault. Now on the football here and now I've
35:19 back to this deeply dipping part of fold here. Mm hmm. And
35:25 zoom on this. You can see hang on here, the football here
35:30 it's not clear what's happening here in deformed. So what do you mean
35:35 that? And we can see the general background here coming all the way
35:43 the tip of the fault. That to this event here. And I
35:50 see I want to put a fault . I've got some fault terminations
35:54 But in fact, now that's gonna out right about in here. If
35:59 take this yellow event, now I roll that over and just get a
36:04 amount of offset well known this trust . So the fault doesn't propagate all
36:09 way up into the the upper part the structure here, determinants about
36:14 And by taking this yellow event around tip of the fault. I can
36:21 where it lies on the, on football in the front. I confronted
36:26 with the form. Okay, Um, and, and this is
36:40 typical seismic example. I've got a defined thought propagation fold here. Somewhere
36:48 here. I have my thrust fault responsible for the following. But in
36:53 forum itself. So I've got all . All right. Um artifacts of
37:01 seismic processing migration sweeps coming in here this orientation. But here in this
37:08 propagating down through here. And so seismic data here in the forum is
37:13 not a reliable indicator of where the the former lies. And that's
37:23 that's important for our trapping in generations . If I put the fault of
37:30 base of that wipe out song, get a large degree of did dependent
37:36 and not dependent on the fault for . If I put that fault up
37:41 in the section here. Now, dependent on false hill to trap any
37:46 in here and his son much much higher risk, lower volume intentional
37:55 here with the fault. It's deeper the section. And from from just
38:01 scientific data, we can't we really distinguish between these two possible interpretations.
38:11 right. Now, here's the here's seismic example applying that concept of um
38:19 preach on baseball. So there's there's seismic section. There's to see for
38:27 So the top of that gives me the basic correlation, my hope for
38:34 in the section. Does it go in this section? If I go
38:38 the central axis of the green here the fault of the semifinal access to
38:43 green here. that's more or less to the blue here. So that
38:49 me um mhm. A good approximation where the green should be here.
38:55 I go deeper in the section down the red in the orange levels
39:00 See now my regional level changes from to here. It should be parallel
39:07 the sea floor here, some parallel the green. And so it should
39:12 across here and the red in this of the sink line should be deeper
39:18 down here. One so that the level from this incline to this incline
39:24 constant across across the fold. Alright. So um I'll give you
39:37 as a handout again. The seismic fault propagation fold. Look at the
39:45 offs on the two sides of the the faults here. And do they
39:51 ? What do the differences apply across thrust? If this is a correct
39:57 ? And where where should this fault ? Out into the section down in
40:04 ? Mm hmm. So take take few minutes and don't work. This
41:13 is the green vertical line supposed to part of the fault. I'm
41:18 No, I should have pointed that from the green vertical line here is
41:22 is a well log. Okay, so we've got a we've got we've
41:26 a well here with tops picked in . Well, okay, anybody want
45:47 volunteer to talk about this. Don't shy. Um If I can
45:59 I would say um the hanging wall offs. They do know much of
46:05 foot wall. Yeah. Yeah, that's exactly right. If you look
46:10 the hangar all along here, the offs here from this guy on down
46:17 much different than the cut offs here we got a pretty thin layer between
46:24 green and the red that's constrained by well here and here. We've got
46:28 thick layer between between the, the green and dark green. It's different
46:35 what we've got here between the light , the dark green and also a
46:39 layer here between the green and the . So the cut offs don't match
46:43 the fault. Mm hmm. Better the regional level concept. Again,
46:49 I project from the sin client here to the front of the limp
46:55 These guys should come up much higher the phone in here so that I
47:00 about the same thickness with the between greens and the green and the red
47:06 both sides of the faults here and . Fun. And that's important because
47:11 it will do is come on from from a fault propagation for, you
47:16 , basically eliminate the faulty at the of the section here. That's
47:22 yeah, correct. Um, so the change and the change in
47:33 The change in cut offs across Mhm is telling you that these events
47:37 to occur higher in the front of fold here and that's consistent with projecting
47:44 regional levels from the trailing edge Out to the front of the
47:50 Across the fold here and then we all these guys up and give you
47:55 thickness is equal cars on the two of the fault here tonight. All
48:08 . So for to summarize this section thought propagation falls. This is an
48:14 of fault propagation fold. I'm increasing slips. I go from the upper
48:20 to the lower model here as I that slip. There's no change in
48:26 displacement of the tangle beds here. maintain the same same regional level across
48:34 the floor from here to here, tip is bending parallel here and then
48:42 to cut up section here where it up section, it projects into the
48:48 clonal axis of the fold here, hmm. And this this nick point
48:56 the fault cuts up section space constant increasing deformation As I increase the
49:02 That fault propagates further and further up the section I was projecting into the
49:08 client. My full amplitude increases the the length of the falling increases that
49:16 dip of from increases to become And then these axial surfaces appropriate with
49:24 fault as the fault pros the fault decreases update from a maximum here along
49:33 base. Two Minimum 20 value here the Fault Chip. Mm hmm.
49:42 that means seismically these deep limbs are to be just wiped out zones.
49:49 background dip here will define what the of the fault is. You're deeper
49:54 the section. And that fault tip to project up into the base of
49:59 wipeouts zone here and did not break the not break through the white boat
50:05 either at the same point or at crest. Right. Um Alright,
50:16 going to change topics and talk about falls. Why don't we take?
50:22 don't we take a 10 minute break ? So come back and Um five
50:28 past the hour. Um We'll go and talk about what are called detachment
50:38 . The folds. We've talked about far the fault Ben folds. And
50:41 fault propagation folds. The full geometry always a direct reflection of the fault
50:49 . And now, what we'll see these detachment folds, This is a
50:53 of full structure where the fold is of the fault geometry. So,
51:05 , we're still talking about thin skin . But now we're going to be
51:08 about detachment. Foals where the full is independent of the fault geometry.
51:21 , so here are here and here examples of detention fools. Here we
51:28 . The full bend falls. Before falls. Mhm. Here, the
51:35 leg dip is parallel to the dip the fault ramp here. And the
51:41 in the dip in the defamation in of the fold here is a function
51:46 the displacement on the on the And the geometry of the fault with
51:51 attachment falls like this. We're detaching a assault or a shale ductile layer
51:58 here. That allows this fall to form like like a bend in a
52:05 when you slide a rug on the and it's independent of the fault geometry
52:11 . So these detachment folds Arbuckle folds above the detachment layer of ductile shale
52:17 salt. They're independent of the underlying geometry. They can be symmetric or
52:24 they're actually symmetric, they can reverse along and across the full strike.
52:31 when they are faulted, defaulting is to the folding and they're very
52:38 They occur in all these different mountain , the euros, the maritime
52:42 parry islands, Full belt in northern Franklin mountains, the brooks range,
52:48 Appalachian plateau in new york and That's a gross and the soviet,
52:54 . Full belt in Bolivia and Okay, so at the start of
53:02 we talked about how the critical the first sort of control on full
53:06 belt structures. And then um where get a shell based attachment, we
53:12 a high critical taper and this is we get the folk Ben folds and
53:17 fault propagation folds with a detachment in shale layer and everything verges consistently towards
53:23 basin of the foreland where we have salt based compression all structures if low
53:31 week Tacoma. And this is where get the detachment folds. And you
53:37 see here with this week paper based the weak basal detachment here to get
53:44 version equally in both directions. And are what we're going to give
53:47 The detachment falls. So these detachment are characteristic of of the tectonic
53:56 An assault based or shale based detachment a low critical taper and the the
54:08 circles here, I'll show detachment full belts, the red dots here,
54:13 show shell beach detached for sale base thrust belts. And here in the
54:21 we have salt based attachments with a of detachment folds rather than fault Ben
54:27 fault propagation folds. So here are examples on this is a line drawing
54:39 section of a symmetric folded attachment fold by sheer along the base of this
54:47 . The core of the detachment fold filled by this psalter of pressure
54:52 and there's no fall ramp breaking through here. This is an example from
54:58 Euro Mountains um with a basal detachment assault shown here in the black of
55:03 basic layer, and then all these and varying geometry folds up shallower in
55:11 section overlying overlying the detachment layer down in the snow. Okay,
55:25 so we can classify these into different based on their full geometry and their
55:31 geometry. Here in this column, have basically symmetric structures with amplitude increasing
55:38 here to here and shortening increasing from to year. With low amounts of
55:46 , we get a low amplitude symmetric as a shortening, increases the amplitude
55:51 that phone increases. We got a harmonic full shown here with um it's
55:58 limbs than this open fold here with shortening. This becomes a very high
56:05 fold on what's called the liftoff fold the structure is completely detached, it's
56:11 lifted, lifted off the attachment later here at the base of the
56:18 And depending on the geometries and how evolved, we can get symmetric fold
56:27 as well as the symmetric faults here with increasing shortening these symmetric or asymmetric
56:36 can become faulted or false, develop the limbs and break through propagating both
56:42 and downwards into this section. Thank . And with continued shortly. I
56:47 we can get these uh multi detachment layers where the fault propagates up through
56:54 and then breaks out in the opposite here, flipping the versions a long
56:59 to transmit falls. Okay, so are characteristic features of fault propagation versus
57:11 folds. So here on the I have a fault propagation fold.
57:18 , the geometries that we talked about on with a flat here, fault
57:24 up section back limit appear is proportional that. Hey son, parallel to
57:33 dip of the ramp here, the decreases upward on projects into the sink
57:40 of the, of the fault propagation with the trip share variation on
57:46 The geometries are all similar except now have a small football sin klein and
57:51 four line is broken through by multiple of shear deformation in the detachment
57:59 Shown here, I start with a without fold that's basically lifted off from
58:07 detachment later here, material flows into core of the anti. Going here
58:13 fill the space problems here, I a football, same client here and
58:19 fault made breakthrough with continued shortening through , wow. Or in a symmetric
58:28 like this balkan breakthrough. Both the in the back limb here giving you
58:33 kind of keystone structure completely detached from underlying detachment layer. Here, I'm
58:42 material flowing into the core of the here to spill the to fill the
58:47 formed by this and a client liftoff . If mm hmm. So here
59:04 Here we have three examples of the geometry interpreted in three different ways here
59:11 have the self similar fault propagation fold we first talked about when the fault
59:18 , ramp cutting up session here, tip here, asymmetric, full converging
59:22 the left up here and the back up here is equal to the dip
59:29 the fault's ramp here. The sin projects into the tip of the fold
59:34 . Um with this tri share fault fold. The back leg dip is
59:41 to the dip deeper part of the here. But as this fault propagates
59:46 section. Um I got a steeper And overturned lamb here in the four
59:53 . And um change in thickness across forearm here with a faulty detachment
60:01 Shown here, I have the same in the shallow part of the
60:08 but now I don't necessarily have any in this deeper part of the
60:13 If I do have a fault, starts in the limb itself and propagates
60:17 and downward. And the geometry of fault is independent of the of the
60:25 of the fold. So here's here's nice example of detachment liftoff phones
60:35 You can see this detached liftoff folds in here. And inclines here
60:42 sink line here, the detachment cutting section here going bedding parallel here,
60:48 no relation of the full geometry to full geometry and the hanging wall here's
61:01 Here's another example from the Canadian Mhm. She That's coming along here
61:08 asymmetric fold here with no fault in basement section here, you see the
61:16 fault here and everything is just falling the She lied. The call marked
61:22 down in here. So I detached with no no independent fault underneath it
61:36 related fault in the base of the . Here's a nice example from the
61:45 slope of Alaska detachment layer here. fold here, symmetric in this case
61:53 false, starting to propagate through their phones here. And I go through
62:00 . Space in the core of the filled by the shale. Being pushed
62:04 into that. Yeah, that space fill that space. And here's an
62:15 from the swiss alps. Is he coming through here, overturned here,
62:23 up, spending parallel again here. . Detachment layer here with the shells
62:30 salts here of outbreaks here filling up the core of the fold in
62:42 Here's a nice outcrop scale example, actual detachment layer here and then all
62:49 detachment phones. This harmonic detachment falls allowing that detachment. Alright, this
63:02 from pennsylvania. Nature's the Appalachian valley ridge in the valley and ridge
63:07 Out here, we have a assault attachment and we get all these all
63:13 symmetric folds forming the antique lines and lines in the valley and ridge
63:18 Here, here's a nice this terrible section of that, mm hmm.
63:29 can see the detachment layer shown here the purple with these detachment folds overlying
63:37 detachment layer verging in both directions, towards the foreland, verging towards the
63:43 here and then false, cutting through section here. Um giving your fault
63:50 attachment fold where the fault geometry is independent of the full geometry. Here's
64:02 example of seismic from the valley and province. You see the mine,
64:10 reservoir beds in this case, the shale, shown here by the
64:14 by the rent on this line. wipeouts out here. And the actual
64:22 player here. Mm hmm. Shown the change in thickness. No,
64:29 fault, no fault. Ben no fault propagation fold underlying the structure
64:35 . Just the detachment fold with an layer shown here, here's a cross
64:46 of the Ural mountains from the swiss . You see the salt layer here
64:52 then here and here to get these detachment falls and in this case of
64:59 propagating both upward and downward from the of the fold. But the full
65:06 is independent of any fault geometry, in the section. Another example from
65:19 Ural mountains, the detachment layer here unfolds overlying that here. Here and
65:28 and here. You see the shortening increased so much that the thrust is
65:33 from this part of the force. was close to the crest of the
65:39 . It's now propagated out this way the left, in down section,
65:44 the right, giving you this very faulted the testament for representing very high
65:50 of shortening. Okay, okay, Zagros full built in Iran, one
66:00 the most prolific, probably the most hydrocarbon province in the world. All
66:06 , you see the all these all black polygons represent detachment folds with oil
66:21 . Here's an example where we have 3 different cross sections from different positions
66:29 strike basement faults and folds here of right layer here that forms an attachment
66:38 . There's a shortening increases in these faults, provoking the player in the
66:44 detachment. Later we get all these folds. Um and in this case
66:53 in this case the asymmetric version in directions verging in the wow towards the
67:02 fault, propagation direction in verging towards inter land shown here in asymmetric
67:08 Mhm. With extreme amount of he's going to become faulted and broken
67:13 like this to give you these foster forms from here and here.
67:23 so here's an example of seismic from Zagros Mountains. You see the basement
67:30 here represented by these relatively continuous The attachment later here and the detachment
67:38 folds. And the shallow section here sizing wipe out charge where you can
67:45 the generally tipping bets here and then get hints of that attack unfold
67:50 but the dips are so steep that much you just don't images seismic
67:55 you can see the big changes in of the detachment layer from the thick
67:59 to a thin here to a relative . Over here again. Okay,
68:11 in the north slope of Alaska, santa rosa mountains. You get these
68:18 phones overlying from the basement involved structures . So here we've got mm hmm
68:27 propagation fault. And but duplexes that talk about next. And then overlying
68:32 we have a detachment layer here within within highly overpressure Shayla kayak shale in
68:40 case, in the lisburn limestone overlying is a relatively um relatively strong mechanical
68:49 . And that reforms to give you these detachment folds that are independent of
68:55 underlying fault geometry. And these are example cross sections from the parry islands
69:08 with the arctic ocean in Canada. software? So I would have shown
69:16 and mechanically strongly relying that that's folded faulted and generates all these detachment from
69:26 up shallow in the section here. you see more clearly here where there
69:30 deformed here here, faltered detachment phones here and here on this section.
69:38 symmetric geometry is not not converging any direction. Just same wind, it
69:45 folds throughout the section. Okay, Mexico from camp engine bay.
69:57 we have more salt based attack unfolds , see the detachment later coming through
70:05 and then these um concentric detachment filets that detachment later and no independent of
70:15 fault geometry. The the salt down is really unfaltering except possibly here we
70:22 a fault propagating both up and down . Overall the geometry down here is
70:32 johnny. So here's the here's an restoration of that where I've got my
70:42 reforms here. My detachment layer of salt here shown in the dark load
70:48 false have broken through the fall into here in here, in the base
70:53 the section here and that that gives a restore herbal section where the assault
71:02 restored to a constant thickness here equal the original thickness in the some clients
71:09 and not here. So this this of the section is mine like
71:16 Whether it's deeper part of the section just area balanced. Here's another example
71:25 from campaign J. Bay in Mexico based attachment here in beautiful symmetric detachment
71:33 overlying that salt based attachment in All right west africa in the congo
71:49 , we have all these attachments phones appetite. Salt lying here giving rise
71:55 these detachment fold, symmetric without any . One direction or the other as
72:02 as this whole wedge slides down into , into the basin. Okay,
72:13 an example of a detachment fold called liftoff folds from Tehran where we have
72:19 attachment layer here. Yeah, the phones of relying it here high enough
72:27 here, with sub vertical limits on two flags giving you what's called the
72:31 structure like a fine like a rocket off from the detachment layer here.
72:43 hmm. Southern Bolivia Argentina. We these similar liftoff folds where we have
72:50 bend fold here in the deeper um mechanically strong section, overwhelming that we
72:58 a highly over pressured share the world's formation. It deforms directly and gives
73:04 these detachment fools liftoff structures lifting off underlying basement structures here. This is
73:15 example from Bolivia from the same province . Bend folds here, deep in
73:19 mechanical strong basement. Los molinos highly pressured shale and the core of the
73:26 here generating this detachment fold with symmetric dips on the two flights of the
73:38 . Okay, but we also see in deepwater Nigeria. And this is
73:44 examples from some papers I published that . So here's an example. Um
73:53 at a structured contour map on the horizon here, I hear an incline
74:00 and contour is shown by the black here structure contours, big flat,
74:06 sink lines here and here and and at the continent lines, you see
74:12 the contour lines to come closer to a steep vertical in here. Whereas
74:18 this part of the fold, they a steep vertical. I'm here.
74:21 as we go along the strike of anna klein. This full changes from
74:29 southwest version fault propagation fold here to symmetric fold here with cross cutting thrust
74:36 northeast. Virgin falls along this part the section. two symmetric folds here
74:43 southwest version falls along this part of section. So the geometry of this
74:49 changing as we go along the strike the fold. So here's the cross
74:59 at the north end of the This was the map level here and
75:04 . We've got a detachment fold with starting to propagate through in this
75:10 In this direction. Coming along, to the south, we see this
75:17 kind of a pop up structure of detachment fold with false propagating through the
75:23 lower limbs of the fold here and over here, overall the symmetric fool
75:29 the ultimate detachment layer down here, along, strike on the same
75:37 Now the full versions has flipped to it was verging to the southwest.
75:45 it's verging on the southeast. You the map level here, a gentle
75:49 line here, steve foreland here. detachment level here, coming up into
75:56 caribbean incline here, but with false emanating out into the the core of
76:03 steeply dipping lamb along this flank, along so I can along strike in
76:12 same structure again. Now we have symmetric fold with steeply dipping limbs on
76:18 flanks and no faults going through detachment here, filling in the core of
76:23 anne klein here and coming along further the south end of the fold.
76:31 , the versions flips again where it's version to the southwest here with bust
76:37 deeply typically here, a vertical limit on this. Flying with false propagating
76:43 up and down section propagating down section this detachment layer, shown here,
76:54 on towards the termination of the And now we've got a detachment
77:00 verging to the southwest with the general , let me hear steep some vertical
77:06 here, false propagating through this part the steeply giving land. Okay,
77:15 down at the end of the fold , low amplitude fold, verging slightly
77:20 southwest, false here in the steeply limb. Detachment later down here.
77:28 in three d. Here's what these look like, the purple. Here
77:32 my detachment layer here at the northwest . I have a the northeast dipping
77:40 Virgin thrust fault. And then here this part where it goes through the
77:46 to the yellow, the versions So now I've got Northeast version fault
77:52 to the southwest in the opposite direction what I have here here in the
77:57 of this structure, I've got both of faults. The main fault
78:02 What's a conscience at fault here And that cognac becomes a down I thought
78:07 I come along the trend of the here, then I go through a
78:11 part of the fold where I just a southwest virgin vault down here in
78:15 structure. So this is all within same fold within the same detention
78:22 And these faults were developing as a of the folding rather than what we
78:27 with the fault. Ben folds and fault propagation folds. Right? And
78:40 are three of those sequential cross sections . It's version of the northeast
78:44 It's symmetric here. It's rooted in southwest, similar amounts of shortening on
78:51 one of these. But what's changing the propagation of slip ratio of the
78:56 layer here, where that propagation to ratio is high. The fault is
79:06 is propagating roughly at the same rate the slip. And so that gives
79:14 this fault, This folder furnishing in opposite direction, Where the propagation of
79:21 ratio is .5 where the fault propagates half the rate of the slip.
79:26 get a detachment structure. And finally the propagation of slip ratio becomes
79:33 going to negative .5. Um Where where the slip is much greater than
79:39 propagation of the fault. Then you these folds version in the southwest
79:45 So this change in geometry along the of the detachment falls. It's just
79:49 result of the changing of this propagation slip ratio. There's the same amount
79:54 shortening all along here with the the slip ratio of the basil detachment
80:00 changes from Mhm. Hi ratio here a low ratio here giving you this
80:07 inversions. Mhm. And here's a a cross section of that deep water
80:17 fold. And what I want to here is that in the seismic data
80:23 , where you have this deeply dipping , you have a wipe out
80:26 You know basically no data zone. in this case we had a no
80:33 and also well here with a dip that was running it in these little
80:39 tags representing orientations. So the dips in that dip meter. And what
80:44 shows is that in this wipe out . There are essentially vertical beds here
80:51 their continuous through the core of the . So if we take all that
80:57 into a balance section, this is is what we get where I have
81:01 general back limb here, crest of structure here. These represent my wills
81:07 the denominator data. These two guys here in here, the white,
81:12 white tadpoles along here represent the dips the denominator data. What that shows
81:17 that these beds come over, they flat and then they go vertical through
81:21 and come out again with general dips in the core of the structure.
81:26 I've got no no no faulting through wipeouts on through this no seismic data
81:34 . And within the deeper reservoirs here little no faulting. It's essentially a
81:39 detachment fold, but with some small in here required to get a balanced
81:45 within this part of the when this of the fold. Yeah. And
81:55 some, here's a mountain scale analog this. This is from franklin mountains
81:59 the Canadian full thrust belt. I a salt based detachment down here at
82:04 base of the section in here, get this detached unfold with a gentleman
82:10 Steeply dipping four of them here, like what, what's interpreted here,
82:17 the exception being that this vertical lamb not imaged in the seismic data.
82:28 , okay, buckle folds are one of detachment fold. The simplest type
82:32 detachment folds in this form where you a mechanically strong high viscosity layer within
82:40 low viscosity, um weak matrix detachment here. And so if I take
82:47 beds in short term, the strong will give me these detachment folds as
82:57 function of the as a function of thickness of this layer and the strength
83:01 the layer in the wink. High layers above and below will just fill
83:08 the same clients in the antique lines by this buckle fold. Okay,
83:18 an example model of a buckle They're in the uninformed state here with
83:24 low amount of shortening the low amplitude form. You're starting to see low
83:30 . Your shown by the ellipses on side of that bucket. Full with
83:35 shortening. We get this high amplitude fold with very high strains in the
83:41 , Lionel and adam clinical axes Now and then these these buckle falls
83:53 be classified in different ways where everything the same antique Lionel amplitude pairs is
84:03 here. These are defined as harmonic where everything is so parallel in a
84:10 like this where you have one strong here and then thinner, more ductile
84:16 above and below. You get these harmonic potential structures. And this is
84:23 polly harmonic folding here, where you just a couple of dominantly wavelengths here
84:33 here, formed by the stronger, mechanical category. Strong leaders in little
84:38 no deformation here in the middle is called dis harmonic folding where this folding
84:43 not reflected in the underlying sediments where overlying sediments. No. So here's
84:56 example of a dis harmonic folding You see that the very tight an
85:03 structure here tights in clonal structure here with a detachment somewhere down here below
85:10 base of the outcrop. Okay, types of detachment falls, we have
85:22 dis harmonic detachment folds where you have challenges in the outer layers and dis
85:28 and non personal geometries in the lower . Oh, the phone's all terminating
85:33 detachment liftoff folds where we get these ice. O'connell and O'connell geometries in
85:39 core of the unit. But with week lower unit and all of the
85:45 in the Where are you mechanically week ? At the base of the anne
85:54 . Yeah, So here's an example a dis harmonic detachment fold. See
86:00 mechanically strong later here with with shortening gives you an Isaac Lionel fault
86:09 deeper in the structure. This material and flows into the the core of
86:14 anne klein, mm hmm. In the cumulative sheer is shown by shown
86:27 this political area here. So there's more shorter and more short here unless
86:35 going down and down into the deeper of the structure. And these are
86:42 examples of liftoff phones. These are the swiss alps. See this
86:47 I see colonial structure here and in . I went to eventbrite detachment later
86:54 here at the base of the structure here off the base of the section
87:03 . Alright. In Oklahoma, find Ardmore Basin. We get similar liftoff
87:11 . What? And this example comes the carter knocks field here, we're
87:17 here in the deeper section we have mechanically strong thick Arbuckle section from the
87:23 layer, forming a fault propagation fault and then shallow in this section,
87:29 structure detaches and the springer shadow here this tight almost bicycling unfold in the
87:36 of the structure here, where the is filled in by the springer shell
87:41 , ducked away into that detachment Okay, alright, so we can
87:52 these geometries to calculate the depth to detachment. And the idea of these
87:57 that mhm. Area above the regional here is equal to the area defined
88:07 the displacement and the height above the layer here. So this area syria
88:16 . Equals this area. Di H. And that D. Equals
88:21 original length measured along the folded bed the present day length represented by
88:29 Want to shorten the distance here and just ultra employee algebraic lee we can
88:36 for age for age equals this equals divided by this. So H equals
88:46 as divided by D. D. this. So H equals the shortening
88:53 the shortened area here divided by the in length between the original beds and
89:00 deformed state beds right now, if measure that for multiple layers we can
89:14 these what are called depth to detachment . We're here here, I've got
89:19 cross section. You're my detachment fault layer one here later to hear,
89:27 one is formed into the Santa Clause here Where this area. S one
89:32 the area of the deformed bed above regional level here this area as two
89:40 the deformed bed. As to this area equals the area of the
89:47 above the regional level. To find and now in these depths of attachment
89:54 plots, this area equals this distance the shortening here. First this area
90:04 this distance age. Two times shortening to report this good D.
90:11 Pairs. We get these kinds of with depth here, the excess area
90:20 . So um The H one 1 H two s. points coming
90:27 and here and drawing a line through gives us the the depth to the
90:36 Where the excess Terry goes to zero the rear detachment reveal here. So
90:43 is a simple case where the slope this line projects right to the
90:49 And my attachment level is the same shown in here. If I choose
90:57 different reference level, it's different from tactical level here. My Hs are
91:03 to vary my Ds are gonna be same and I'll get a plot like
91:08 that doesn't go through the origin butt intersects the Y axis here and intersects
91:15 X. Axis here. And then distance Gives me the depth of the
91:21 relative to my H. one layer . So my true detachment up here
91:27 shown by this distance Which is this from H. 1 to this intersect
91:34 the plot here. Okay. Alright I want you to work in the
91:43 . Step two Detachment Exercise. Alright given you this data I've given you
91:49 excess area for seven different layers. got an example fault propagation fold here
91:57 each one of these layers one through as a different area above its regional
92:06 . That's shown by the S. here. The height of each each
92:10 those layers above the reference level is by These values here. H.
92:16 through H. seven. And what want you to do is take these
92:21 plot them on a dr tat count they're attacking craft like this. So
92:28 these values. Mhm. And plot on this on this graph that I
92:35 you will generate a line that goes each one of those through seven of
92:40 pairs. And the slope of that gives you the displacement and the depth
92:45 the detachment relative to the reference Mm hmm. Alright. So take
92:57 these values a lot of money here the area value goes here? The
93:04 of both? The reference level goes draw a line through those points that
93:11 get. And then use that line estimate the displacement and the the
93:18 Just attachment. Yeah. Okay. So go ahead and work this
93:33 Mm hmm. It'll probably take you 20 or 30 minutes and let me
93:44 . Let me know either with your turning your camera off or on and
93:49 me know when you're done and when done, we'll talk through it.
102:18 mr Nike tennis. You have a ? Um No sir. I'm done
102:40 , Are you? Yes, that fast. All right, Okay.
103:13 you did you get something like McDonald's? Yes, sir.
103:22 Perfect. Mhm. And so the of this line gives you the
103:33 And the intercept here gives you the detachment level intersection um relative to your
103:40 level. And in this one it's the same. So, so if
103:50 excuse me, your line should have down and incited the axis about
104:07 I can't. That's 3.30. Um Did you intercept come close to
104:17 origin here. And so what did get? I'm just finished calculating it
104:26 now. I got 3.2. good. Mm hmm. ST so
104:52 you are you all comfortable with how , how this all comes together how
104:56 works? Okay. All right. if you do this for a different
105:10 level, this line will shift over the left. The slope would remain
105:15 same when you intersect the X Somewhere over here, depending on where
105:20 reference level was relative to the actual level. Alright, moving on to
105:31 detachment faults. And the idea of is that we start with an attachment
105:38 with no faults through it. An layer here are folded layer here and
105:46 increasing shortening and increasing strain, the will initiate in this deeply dipping part
105:51 land here and breakthrough and propagate both and downward into the detachment level with
105:59 shortening that fall can propagate all the down into the baseball detachment. Show
106:05 by this trajectory here and through So now. Now we have something
106:10 similar to a fault propagation fold. the the full geometry is a much
106:17 complex. It is much more complex a much more complex relationship between the
106:22 geometry and the fault. Okay, now faulted detachment faults are ones where
106:36 detachment folds are cut through by forming After significant folding folding is a dominant
106:44 and the propagation of the thrust fault a secondary effective process. Accommodating strains
106:51 with the folding, mm hmm. these are most likely to occur in
107:00 with high competency contrast where you let's say brittle sands or shales,
107:06 sands or terminates in the midst of ductile shales or evaporates. Mm
107:12 A significant variation and deformation behavior may between different units. Remember we get
107:19 dis harmonic and polly harmonic types of . You can get much more open
107:25 folded, much more open and full geometry. Then you get with
107:29 Ben folds or fault propagation folds. initial wave length of the folds is
107:35 by the thickness of that mechanically strong layer. Um, you're gonna get
107:44 any false that form. You get and non variation, non uniform variation
107:50 false slip. If I go back this here, the maximum fall slip
107:56 going to be in the center of fault and it's gonna decrease the tips
108:02 and here in this section and deeper the section. So it's uh very
108:09 than the. Then the typical decrease slip. We see where the fault
108:14 fold. Um And with with tiny we get a transition from folding defaulting
108:31 we get out of sync line faults these decapitated faults that we showed earlier
108:37 the section. Right? So here's an example of a faulted detachment
108:47 You can see that it's a fold over here, overturning here and then
108:52 fault appropriating up through really the core that steeply dipping limb dying out in
108:59 direction into to failure here and here dying out down here into the deeper
109:05 of this nation. Mm hmm. , we also get these more
109:15 doubly variant photos where? And we with a detachment layer here and uh
109:25 ductile detachment layer here, faults propagate and then propagate us back thrust here
109:33 and here giving you these doubly version on the crest of the anne
109:43 Mhm. And in this detachment there's a the early or a low
109:51 example that where I have the overall fold here, false, starting to
109:57 through here and here and generate more and faulting of the section here and
110:07 here will increase shortly. All alright. And these are the type
110:16 structures that we see in the Mississippi fold belt in the gulf of Mexico
110:20 we have. Mhm. The salt here and um detachment folds overlying that
110:28 layer false breaking through both limbs of detachment folds. This is an example
110:38 seismic section from the Mississippi san fan belt. See the salt detachment layer
110:44 just above basement. Multiple reservoir horizons in a symmetric detachment fold here with
110:52 breaking through both the back line in front room of that detachment fold,
111:00 hmm. And this is from, the Perdido fold belt. This is
111:06 actually the great white structure. detachment layer here. Detective folds overlying
111:15 salt layer here diverging to the right and to the left here with false
111:22 through here in here through the highest parts of the fold. Here's an
111:34 of these detachment folds of the kink geometry from the burrito. Full adult
111:40 coin here. King band here. band here, cynic line here and
111:45 here. Another sink line here. here here, here, here and
111:52 . Pretty symmetric folds, overall versions towards the base. In here,
112:04 a zoom be an example of that . Full geometry. We have a
112:09 on a limb here is steep dipping limb here and the steeps in a
112:14 lines incline a limb here and and that example of a box fall from
112:24 north slope detachment layer here are in final layer here with kink hinges here
112:37 here in cross section. It would like this with the kingpins here and
112:43 and now. We start to see space problems here in what fills in
112:48 space. In this case it's the pressured shales flowing into that area.
112:55 that you knew a long length balance these layers and you would have to
112:59 an area balance of this deep, deco mart layer. But there's there's
113:08 example. All right, okay, now, with with continued shortening,
113:20 get this kingpin geometry here, the bands converge at the base of the
113:26 layer and create this technical structure at base of layer here. And this
113:34 on a small scale folding and faulting the shales are evaporates too. Flow
113:40 that dan O'connell core right now this is the same problem inverted where
113:51 have kicked banned here. And king here, the kingpins converge upward to
113:56 point here Where the shortening is zero Michelle longest horizon. And to maintain
114:05 compatibility between these deeper sections and it's sections, we have to have lots
114:11 falls and falls developing in the core this simple final structure here.
114:21 And that's where we get these. are called out of sync line
114:25 Out of sync line pop ups and faults. So here I have converging
114:31 kim bent here, Another king band converging here and I have a shortening
114:38 here, so that I get a a final pop up structure here to
114:45 the shortening the same as that we deeper in this section. In line
114:50 gathered here with kingpin converging here converging , sink line here and then this
114:59 up an incline overlying up to equal shortening of the deeper layers.
115:09 I mean, that's also how we these out of sync line thrust.
115:15 here I've got an under formed state I shorten this, I developed these
115:20 here and here with continued shortening as converge until there's a layer of level
115:29 no shortening here and now I have have these out of sync line thrust
115:36 get the same shortening shallowing section that have deep in this section. And
115:47 an example of that from the I have a kingpin converging here.
115:54 king pan converging here. And now have these out of sin klein thrusts
116:00 on the flanks of this. Uh that shorting that the deeper section experiences
116:09 the shortening and the shallow section up . Um This is an example of
116:17 out of sync line thrust from are pennsylvania valley and ridge, what's called
116:23 buffalo berry, simply mariam. This a Matthew here you see a very
116:28 film geometry, a sharp inch playing violin here, playing a role
116:32 here, dipping into the middle of sink line here in cross section that
116:38 like this. This lamb is this , this land is this land dipping
116:45 into the core of the sink line and then this trust fall is here
116:51 cross section representing an artist's incline. form by the space problem caused by
116:57 shortening of this. This the test fold. Okay, alright to summarize
117:08 thrust belt detachment folds. These are folds, liftoff structures or buckle folds
117:15 a ductile attachment. Typically assault or overpressure shale. They can be symmetric
117:23 with overturned fold limbs. The versions vary along strike and individual falls can
117:30 flip versions along strike like we saw that example from deepwater Nigeria, the
117:37 limbs are independent of any underlying fault If they develop our secondary and
117:45 from the limbs to the regional detachment . So they initiating the limbs and
117:51 upward and downward. Mm hmm. thing from what we saw in the
117:55 band and fault propagation falls. The of the declines and inclines develop space
118:03 . The coral unfolds the results of out of sync line thrust and pop
118:10 mountain climbs and falls. And these very common anywhere. We have a
118:15 based attachment or a highly overpressure shale , the gulf of Mexico, the
118:21 and Mississippi fan, Deepwater Nigeria, southern Andes where we have those liftoff
118:28 ah originating from the overpressure shale, Euro's, the period islands. We
118:33 a salt based attachment kim Petras, plateau, Zagros and the franklin mountains
118:40 Canada longer we have salt based Okay, right, mm hmm.
118:51 comments or questions on that. Before go on to the next section.
119:32 , I'm I'm gonna go on and about duplex structures. Do you want
119:39 go straight ahead or do you want short break in between a short
119:45 Okay, the type of full thrust structure. What are called duplexes?
120:01 we're into this the second to last on full thrust belts. Talking about
120:11 , we're still on the thin skin realm. And now we're gonna talk
120:16 slightly more complex structures and this is cartoon of, of a duplex.
120:27 where we take a a slice from football and propagated up onto the hanging
120:35 , and again, it's inherently restore ble. We maintain constant bed
120:41 Constant bed thickness and slipped in this along the two places will be constant
120:47 both the football and the hanging. here's here's an example of a
120:58 We start out with a fault bend here, where we have a lower
121:05 Iran and an upper detachment. And we take us basically, we take
121:11 slice out of the football. We this initial slice and propagated to push
121:17 part way up onto the upper So we have a small displacement here
121:23 this false slice up onto the upper , and then subsequent subsequent slices break
121:32 in the football, is the football . So this next slice. This
121:37 slice moves up part way up the onto the hanging wall flat and carries
121:43 previous slice along with it and fold . Okay, And now we have
121:54 types of duplexes. one where we these minor fault. Ben phones all
122:00 towards the of foreland in the sense displacement is consistently to the right consistently
122:07 the foreland. Now, with what called passive roof duplexes or triangle
122:14 we get these slices horses piling up as here, but now the displacement
122:20 taken up by a back thrust across roof here. So instead of the
122:27 and continuing on to the right Now the thrusting is going up to
122:32 , to the left, to the here with the tip line for all
122:35 deformation out here in front. So are the difference between typical duplexes and
122:43 roof duplexes or what are called triangle . Yeah, right. So
122:53 Um Two. A duplex is made of minor faults and folds, slices
122:59 horses between a major floor thrust and roof thrust. So these are my
123:08 floor thrust and the roof thrust here these minor fault bend fools being translated
123:14 in the trust direction. We have two different types, those that are
123:23 virgin towards the foreign and those where roof thrust is virgin towards the hinterland
123:31 these ladder or the passive roof duplexes triangle zones. Right examples are comin
123:41 the US rockies, the Canadian And and in Appalachian full thrust
123:48 The southern Appalachian full thrust belts. triangle zones and duplexes can be subdivided
123:56 two types. Warning where the roof cuts up section In a second,
124:02 two with the roof roof thrust parallels hang well bedding. And then these
124:10 these duplexes are important because they give strike closure, but we can identify
124:15 saddle shapes. Inclines in the footballs the thrust. True. So here's
124:24 here's a cross section of duplexes that just talked about. 1234 slices
124:31 All version to the right, verging the falling in Matthew, this is
124:37 the pattern is going to look where you hit. You've eroded through
124:43 floor of the overriding thrust to give this outcrop shape. And then these
124:51 are exposed here, here and here the in the in the outcrop
124:59 In cross section in this direction, have to the major football here,
125:07 fault with lateral ramps here and here then the different duplex slices repeating each
125:14 in in this direction, vertically, this direction, In the lateral strikes
125:25 . Yeah, okay, so, a simple fall been forms. Ben
125:35 forms through the movement of the hang over a ramp where the football ramp
125:41 thrusted. Um You gotta to pledge the overlying sheet is folded into a
125:50 fort bend fold, successive thrust, football ramps, resulting in a final
125:56 made up of multiple folded thrust, fault. Ben folds, hmm.
126:02 final geometry is dependent on the initial between the thought ramps in the relative
126:07 on the fault. And that gets these types of structures. So,
126:17 here we have three different types of all formed by transport to the right
126:24 towards the foreland, mm hmm. here we have a hinterland dipping duplex
126:32 there's a small amount of displacement on one of those. One of these
126:36 . These are the examples of the that we've just been talking about with
126:41 amounts of displacement, I can take slices and totally wow, overlap each
126:48 so that I get an anti formal . Deal with these guys still being
126:54 towards the four line but forming an formal structure there and with even larger
127:04 of displacement, I can move these and further out to the right to
127:09 this kind of foreland and being duplex where everything is transported in the foreland
127:17 in such a large magnitude that I this forming dip to the actual
127:25 Mm hmm. So here's an example the deformation in the overall hanging wall
127:35 . That comes from the duplex So here's my initial fault.
127:42 My 4th thrust here. My first here, my hanging wall decor market
127:48 , My hang wall flat here and I'm going to break out horse,
127:53 out a duplex here and push that up to the ramp here, sort
127:58 this geometry where this has now slid the right, the leading edge of
128:03 is forced up over onto the Hang flat here, that gives the duplex
128:11 the horse slice this geometry and that the overlying thrust sheet to have the
128:17 the same geometry where I have a dip of flat, a minor
128:22 a flat, minor dip of flat then the main fallen dip here.
128:34 , okay, so, so this the variations that we can get depending
128:38 the course length and the relative If I have widely. If I
128:45 wrong, widely spaced horse like I got a full bend fold my
128:52 slice here, my horse slice here a second independent an inclined structure
128:58 at the leading edge of the All right with medium spacing of the
129:05 of the horses from these two and client structures get closer together. So
129:11 have the initial one here, the one forming here, a simple line
129:15 between with these two crests Reflecting the crests of the underlying horses. Right
129:24 closely spaced mm hmm. Ramps. my initial ramp here, mine second
129:32 here And now. I have one of antique linoleum with two individual crash
129:38 forming in an informal structure in In this section I have single crust
129:53 by multiple slices, my initial slice , my secondary slice there.
130:00 And now the the displacement of this greater than the initial displacement here,
130:07 that I get a leading crest here front of the earlier form crust here
130:17 increased displacement of this horse. In of this worst. These two crests
130:24 to give one single crest here and thrust sheets with very large displacement where
130:33 taken my initial forward bend forms, them up here and then formed a
130:38 duplex slice underneath with a large displacement him. I'm gonna get a large
130:44 decline with the single crust here with displacement of the overall structure.
130:59 here we have different types of different of duplexes, depending on those.
131:05 of course sliced geometries. Here we this simple on what what are called
131:12 duplexes where we get a single and culinary more the crest of all these
131:17 slices. Uh huh. Here we a single crest with increasing shortening and
131:29 single. Um again, a single with symmetric with symmetric forms. Names
131:36 the side where I have complete overlap the thrusting. Show here, where
131:42 initial thrust is here, The secondary is here, mm hmm. That
131:48 the displacement of this crust is large That I get one large an incline
131:54 with a gentle back linda pier and steep foreland dip here. And as
132:01 thrusts get shorter, that fall tightens becomes more symmetric. So here,
132:10 with that bottom slice is relatively I'm back to a symmetric and
132:15 but with a high amplitude in this . Alright, in Glacier National Park
132:26 Montana. This, this outcrop. mountain is a famous example of a
132:32 structure where we have floor thrust roof thrust here and then individual course
132:40 here and here, forming the core to place. All right, here's
132:52 example from outcrop where I have one cutting up here. Another thrust coming
133:00 here, emerging up section into a thrust somewhere here. And you see
133:05 football slice is displaced from here to and then displaced again from here,
133:12 here. All right, let's But here's here's an example from for
133:27 Montana. Again, we have a of intricate thrust back here and now
133:34 like in a duplex structure here with roof thrust Propagates up here, out
133:40 the four land and that it is by the thrusting of this underlying Or
133:46 this underlying? Do blood structure? carries it up and forms an overall
133:50 colonial structure in the hanging all Here's another example from from Montana.
134:04 this we can we can see this and outcrop here and the Titone anne
134:12 main floor thrust here, cutting up here going bedding parallel onto um football
134:22 here. The duplex slice cutting along on the floor, thrust, cutting
134:28 section here on the ramp and then upward onto the roof thrust here.
134:34 form is all antique Lionel structure of overlying thrust sheet. This is the
134:41 is the seismic data. Here's the drawing interpretation of that charging data with
134:48 wells in here. To give you information about the repetition in here.
134:53 the seismic data alone or you would . You just don't have this.
134:58 wouldn't see it. Okay, Most the gas fields in the Canadian rockies
135:09 duplex slices like this. This is Matthew of the Waterton gas field with
135:15 contours on top of the Mississippi and BBC. One crest here and then
135:22 slices here and here and here and . And each one of these forms
135:28 own gas pool, its own gas . Mhm. Here's what it looks
135:34 in cross section. So the main thrust coming up here, lots of
135:40 indicates out here in the upper and cretaceous shown here in the green and
135:48 the Mississippi and carbonation down here from duplex structures where you have multiple slices
135:56 multiple slices of the football collapsing, a large duplex antique memory in here
136:10 a here's a simple, more simple from the savannah creek field roof thrust
136:19 , um, with duplex slice duplex slice here with the ultimate floor
136:26 here. I'm betting parallel back here the section coming up and then coming
136:31 section here. Mm hmm. here's a seismic profile across and um
136:52 santa clone in the Appalachian plateau. everything here is verging verging to the
136:59 transported in this direction. Here's my hang hang all she here and then
137:09 duplex structures down here where I have series of in briquettes within the
137:17 within the artificial carbonates here, with floor thrust here. Here's an example
137:31 interpreted seismic data from the Appalachians a of duplexes here. Um, football
137:41 here cutting up section here, giving a fault bend fold here, but
137:50 you have a second fault Penfold here so this pair of fault penfolds gives
137:56 a duplex here, at the leading of this trust sheet. Coming back
138:01 , you have multiple slices again. slices here, forming a duplex of
138:07 three horses. Back here, coming south, we see a similar structure
138:16 where you have the main for all for us. Here, for Ben
138:22 here, out in front and then here towards the hitch blank. Get
138:26 duplex structure with 1, 2, repetitions of the carbonate slices here.
138:38 here's the prime mountain duplex, also Appalachia floor thrust here, cutting up
138:45 along each one of these roof thrust . The thrust At the base of
138:53 one of these two Plex slices cuts section and merges with the roof thrust
138:58 . So you get this. This out both duplex slices consequentially, this
139:03 be the first. This would be second to form this overlying guy.
139:08 would be the third to forming This overlying guy. And then this
139:12 be the fourth who hasn't propagated all way up here yet. And here's
139:21 example of seismic from that structure. I have the floor thrust here.
139:29 initial ramp cutting up section here. roof thrust shown here in the red
139:34 line. And then each one of represents a duplex slices with the order
139:39 carbonates here, showing the glue on this overall thrust. The Ben hur
139:46 into a large scale anti korean. . Looking at another side of this
139:59 through that pine mountain thrust. We the football flat here, cutting up
140:05 here on to a hanging wall flats the section here, followed by this
140:13 cutting up section onto the same hanging flat here. In this last
140:19 cutting up section forming the overlying borderline rods. So, here's an interpreted
140:32 of that where we have the floor coming along here, betting parallel cutting
140:37 section onto a flat here. overall we have a full bend
140:43 but then the football has collapsed along too, from this. Or slice
140:47 duplex slice deforming the online roof thrust into this. The mandalorian.
141:03 right, so now we're going to about triangles, owns wedges and passive
141:07 reflexes. And all of these are to the duplexes. We just talked
141:13 where the duplexes are verging towards the out here. To the right,
141:18 now the displacement on these is compensated roof thrust with virgins backwards towards the
141:27 . And so these are these are sort of inserting themselves in between the
141:33 thrust here and the roof thrust And this. This deformation that tips
141:39 Anthony tip of this roof thrust so it doesnt property it off to
141:44 for land, but in large amounts displacement can be accommodated and and commentate
141:53 a very short distance. This way these bathrobes, there's an X.
142:03 section across the passive roof duplex. see the floor thrustmaster thrust coming up
142:11 , verging towards the foreman here. slices here. 1, 2 3
142:17 slices. And now the displacement on is taken up by displacement on a
142:24 thrust here. So these guys are wedging themselves between this hanging wall sheet
142:30 this football sheet. And the displacement these duplexes is taken up by back
142:38 . That thrusting No longest overall. were thrust. Mhm. Okay,
142:50 look at an example that from the plateau again through here. But here's
143:04 the west, northwest here, southeast . Main thrust cutting up section
143:12 This section displays to the right, hmm, wedging itself under this section
143:18 , forming it a passive roof duplex a simple passive roof duplex. It's
143:23 the triangle zone in this, in section. All right. And here's
143:34 line drawing models for evolution of these triangle zones. So, I'm gonna
143:39 this sheet, move it up, fault bend. So I'm going from
143:43 flat to Iran to a flat And the displacement on this is going to
143:49 itself to the left, crying this up. So I get this kind
143:55 displacement along here. So hang all moving to the left and and wedging
144:02 between this higher hanging raw shoot here it back for a sense of displacement
144:07 here, this thrust cuts up section which he is, Which is what
144:14 it as a Type one triangle Um And this is an example from
144:22 southern san Joaquin valley, the wheeler and a con wheeler Ridgefield. And
144:27 is all constructed from well sections. one of these vertical profiles represents a
144:33 with a camera and sp mark. , my floor thrust comes through here
144:42 duplicating these beds carrying them up into wedge. Mhm, wedging themselves underneath
144:49 hanging all bets here with the displacement taken up by this thrust that cuts
144:55 section through here and ultimately goes out the right here. This shows a
145:02 of this section where I've pulled this out to the right, he's now
145:07 back here and all these beds collapsed down to a horizontal data all through
145:19 . Here's another example from the same at different cross section, different wells
145:26 , each one of these represents a within a Cameron and sp profile football
145:31 here, football flat, ran football , mhm, thrush eat wedge moving
145:41 the left through here, pushing these up with the displacement. Now being
145:48 up by a back thrust, cutting section here going bedding parallel here.
145:53 I I can restore this by pulling section out to the right, just
145:58 in the previous section. So I this geometry. All right right,
146:03 nice. These different wells show the of displacement this well is offset to
146:08 . This well is offset to This well is offset to there.
146:12 you have these piercing points and particularly displacement theory what the senators
146:24 So here's a simplified model of that arrange structure starting from the un deformed
146:32 , moving the wedge to the left here, fault cutting up section
146:37 the roof trust cutting up section here then betting parallel here. And as
146:43 continue to move this wage to the , this fault tip propagates to the
146:50 and I kept more and more section up over the top of this,
146:54 me a higher belief and climb with progressive deformation across the bottom here.
147:07 then we have geometrically these type two owns where the idea is that the
147:14 thrust is all getting parallel, so , there's my initial Feldman fold and
147:23 I'm going to wedge this piece underneath the left. I wish him along
147:29 uplift your line beds and all that . I was taken up by putting
147:34 attachment along the roof with this So in the previous examples where this
147:41 up section. Now it's all betting . The roof thrust is all betting
147:49 . Mhm. So here's here's some of that. We started in the
147:56 formed state and initially moved this wedge to the right, there's my um
148:05 detachment level. Here's my number detachment . And now, instead of having
148:10 fault been fold, the propagates out the right. I'm going to terminate
148:14 fault here in all this displacement is out by a bedding parallel back thrust
148:21 here. This number to wage, breaks out here and the fault tip
148:28 a little bit towards the hairline, the overall displacement is again taken up
148:33 back thrusting along that overall roof thrust increasing amplitude of the an incline
148:42 With the collapse of this 3rd The whole structure propagates slightly towards the
148:48 . But the main displacement is taken by this roof thrust. I'm in
148:52 high life decline decline at the core the structure here. All right,
149:03 hmm. Triangle zone from the Canadian . This isn't. This is an
149:10 . You see the floor thrust Floor level detachment hanging around here,
149:15 detachment here in this this worst Father ensuring itself prying these other layers
149:23 . Want to form on triangle zone . So, here's a triangle zone
149:33 multiple slices. All right, main thrust here, main roof thrust bedding
149:41 here and then All through here we a series of duplex slices waiting in
149:47 between the Kurdi. Um and the trying this government partitions sheet outwards.
149:55 with the main roof thrust here getting across the top of all these to
150:00 slices. Okay, and here's here's example with the rest of partial restoration
150:12 that. So my floor thrust is , my ramp is here cutting up
150:17 , my hanging wall flat is here now I have these duplex slices collapsing
150:24 football carrying things up towards the Over the ramp here onto the
150:29 but rather than propagate towards the all this shortening is taken up by
150:34 thrust displacement along this roof thrust This shows a partial restoration where we've
150:43 these slices and pulled them back to and left this roof thrust hanging up
150:50 the wall to show how that restores flat onto of this flat ramp geometry
150:56 the football here. So here's kind here is possibly the mother of all
151:06 of duplexes. This is from Taiwan of complexity in Tehran major floor thrust
151:14 , cutting up section here onto a parallel flat here and then you have
151:19 thrust slices here here, There's 123 9 10. There are 10 Duplex
151:27 in here with different watching geometries. here, for from one energy can
151:35 here here forming a wedge between this thrust and this roof thrust and then
151:42 forming another sequence between this for thrust this roof thrust with the overall major
151:50 here now highly deformed too steep to really steep tip back towards the
152:03 Right now one of these things these do is generate strike closure. So
152:09 is serious here. Matthew in a of quarantine cross sections from Matthew
152:16 across the duplex structure here. This , prosection PV products is this section
152:23 . B prime here, see the hanging around sheet here and here and
152:30 deformed by all these duplex slices here the football and the hanging wall.
152:36 these duplex slices lift up the hang she's here. So where these duplex
152:43 are present to hang while she is up. Whether or not present like
152:47 any prime here that she is not up and you don't have football closure
152:54 . Mm hmm. In strike cross C. C prime. We're looking
152:59 here, there's my major roof Here's my second roof thrust. Here's
153:08 full thrust here, my duplexes forming and they lift up this overline sheet
153:16 give you strike closure in the strike to give you dip in the strike
153:22 , its surface of crop. But generates is this kind of saddle shaped
153:26 line. Overall, I have this here and here, probably get your
153:32 , full length just below the, below the outcrop of the thrust
153:39 Turn and where it's lifted up by duplex. It's lifted up here to
153:45 relative high, giving you the saddle incline plunging off parallel to the strike
153:51 the font here and plunging off, into the strike of the fault
153:58 All right, this is an example cuervo field in Bolivia, the major
154:04 thrust occurring along here. Um Outpour currently on here and then here I
154:12 this saddle shapes incline incline plunging off the south here, sink line plunging
154:18 to the north here with the crest . The location of that underlying
154:28 Okay, here's another example. This from the will Burton fields in the
154:34 basin in Oklahoma. The main thrust , the whole series of intricate thrust
154:40 it here towards the hinterland. Outboard thrust here, this carbon fall
154:47 here we have at the surface. will Burton cynical on which plunges off
154:52 the southwest here, north of the here and this immediately over lies this
155:00 Arbuckle fault block. The the uplift this Article four block is what lift
155:06 guy up and gives us the saddle and crime. So in cross section
155:15 this direction a prime here you see main choctaw thrust coming up here,
155:23 carbon fault coming up here will Burton client here and then this will Burton
155:29 line. Over lies this Arbuckle horse where the deep basement and article is
155:37 and carrying upwards to create another but also to give you the saddle
155:44 incline in the unprofitable. So summary duplexes and duplexes are defined as minor
155:59 false slices your horses between major floor roof thrust. So, major floor
156:06 , major roof thrust here and then duplex slices indicating different slices of the
156:13 here is the football collapses. Generally we get these full inversion complex
156:22 but we also get passive roof duplexes Toronto zones where the displacement of the
156:28 slices is compensated by back thrusting across thrust. Like this. Examples of
156:36 come from Montana. Full thrust Canadian gas fuels and Appalachia. The
156:45 zones can be subdivided into two Type one, where the roof thrust
156:50 up section In type two, where roof thrust parallels the hanger diabetic.
156:56 this would be an example of the to section here. And then what
157:01 duplexes give rise to in the strike . Are these subtle shapes inclines that
157:08 you have strike closure in the football the major fault here. Okay,
157:21 comments or questions on this section. hmm. Alright, that was that
157:44 a lot of material that when we through today with the fault propagation
157:50 Treasure fall, propagation, phones, phones, I mean, detached
157:55 And then these duplex structures. any questions on any of those things
158:00 we talked about. Alright, if no no comments or questions, um
158:16 break here for the day and we'll early And we'll pick up again tomorrow
158:21 8:30 with talking about the types of fields that are formed by all these
158:30 .
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