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Author | Topic: Evolution. We Have The Fossils. We Win. | |||||||||||||||||||||||
edge Member (Idle past 1736 days) Posts: 4696 From: Colorado, USA Joined: |
I guess I just don’t understand the mechanics of it. That the tilt is at the same angle makes a lot of sense to me if the fault occurred later, or at the very end of the tilting event. But if the fault was there I can’t figure out why there wouldn’t be any slippage at the fault that would see one side tilted more than the other.
Sure, that could happen. Depends on fault geometry and the degree of offset. Remember, this is, in large part, a schematic section, so it could as well be true here. And all that I think Moose was saying is that you cannot tell if the fault came first or the tilting. We truly cannot tell from this diagram.
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edge Member (Idle past 1736 days) Posts: 4696 From: Colorado, USA Joined: |
Edge and Moose think it is related to the tilting of the Supergroup. So there is an alternative possibility there. And there doesn’t seem to be any upper resistance that would vary enough to cause the fault, as well as the evidence of cross-cutting which shows that the fault occurred before the upper strata were there at all.
Right. Even if the Shinumo were thrust into the Tapeats (all the way through, actually) there should be some differential movement between it and the Hakatai and the Dox, since they do not penetrate the Tapeats. The faults that offset the Supergroup Rocks is cut by the unconformity, as are the various intrusive bodies in the Precambrian rocks. The dikes are cut off and the granite plutons are cut off by the unconformity. But to top it all off, there are erosional gravels derived from the Supergroup and the Vishnu rocks at the base of the Tapeats Sandstone. This is the drop-dead argument against Faith's upthrust of the Shinumo. The rocks were hard enough to form erosional gravels and dot no exhibit a shear texture that would be necessary in Faith's scenario.
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edge Member (Idle past 1736 days) Posts: 4696 From: Colorado, USA Joined: |
So in this view the fault and the tilt were simultaneous, The Supergroup was being pushed up into the Tapeats and pushed horizontally under the Tapeats as well (the distance of a quarter mile, which is how far the quartzite boulder embedded in the Tapeats traveled from its origin in the Shinumo.) The forces split the Supergroup, its upper edges were eroded off, and the movement that caused the erosion stopped the fault line where the Supergroup met the Tapeats. That's why the "step" is simply removed and didn't penetrate into the upper strata.
You do understand that the Canadian Rockies topography that you see is formed by erosion, do you not? I like it. What do you think? Do you understand what I'm saying here?
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Faith  Suspended Member (Idle past 1474 days) Posts: 35298 From: Nevada, USA Joined: |
No I don't know what you mean by "formed by erosion." I was focused only on the form of the strata.
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Faith  Suspended Member (Idle past 1474 days) Posts: 35298 From: Nevada, USA Joined: |
But to top it all off, there are erosional gravels derived from the Supergroup and the Vishnu rocks at the base of the Tapeats Sandstone. This is the drop-dead argument against Faith's upthrust of the Shinumo. The rocks were hard enough to form erosional gravels and dot no exhibit a shear texture that would be necessary in Faith's scenario. Erosion will do for my scenario, don't need shearing. But what do you mean by "at the base of the Tapeats?" IN the Tapeats or below it? Offhand "derived from the Supergroup and the Vishnu" sounds like a confirmation of my scenario. Edited by Faith, : No reason given.
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Faith  Suspended Member (Idle past 1474 days) Posts: 35298 From: Nevada, USA Joined: |
The faults that offset the Supergroup Rocks is cut by the unconformity, as are the various intrusive bodies in the Precambrian rocks. The dikes are cut off and the granite plutons are cut off by the unconformity. Yes, cut off by the unconformity. That's part of the evidence that the strata above were already there when these events occurred: the faulting, the tilting, the granite and Vishnu formation, the erosion etc, and that is evidence for the occurrence of the tectonic force in the "Precambrian" rocks after all the strata were in place. Edited by Faith, : No reason given.
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Faith  Suspended Member (Idle past 1474 days) Posts: 35298 From: Nevada, USA Joined: |
- Since they ARE split, that now adds to my view that the Paleozoic strata were all in place, their weight being a counterforce to the tectonic pressure on the lower rocks that restricted them all beneath the Tapeats, the lower force being just enough to create the Kaibab Uplift or rounded hill over the Supergroup, AND ALSO CAUSE THE SPLITTING OF THE SUPERGROUP AS IT MET THE UPPER RESISTANCE. Otherwise I don't see a reason for the split. Edge and Moose think it is related to the tilting of the Supergroup. Of course it is.
So there is an alternative possibility there. I don't think the split would occur without resistance to the tilting, which is what fits my scenario so nicely. The whole block of strata would simply tilt up into the air without that, there wouldn't be any faulting or splitting.
And there doesn’t seem to be any upper resistance that would vary enough to cause the fault, as well as the evidence of cross-cutting which shows that the fault occurred before the upper strata were there at all. There is no upper resistance in the conventional interpretation, only in my scenario. And why would it have to "vary" anyway? If the Supergroup is tilted and pushed by the tectonic force up into the lower surface of the Tapeats with all the weight of the strata above it, that counterforce of the weight would put strain on the Supergroup, which I think accounts for the faulting and splitting which are simultaneous. That same resistance accounts for the eroding away of the upper corners of the Supergroup. The erosion itself implies the horizontal movement I keep saying must have occurred, though yes, the only actual evidence of the horizontal movement is the position of the quartzite boulder, but such movement would account for the way the fault line is cut off by the unconformity, meaning that cross cutting relationship that would show the strata were already there was prevented in this case. Edited by Faith, : No reason given. Edited by Faith, : No reason given. Edited by Faith, : No reason given.
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edge Member (Idle past 1736 days) Posts: 4696 From: Colorado, USA Joined: |
Yes, cut off by the unconformity. That's part of the evidence that the strata above were already there when these events occurred: the faulting, the tilting, the granite and Vishnu formation, the erosion etc, and that is evidence for the occurrence of the tectonic force in the "Precambrian" rocks after all the strata were in place.
The unconformity cuts both the bedding of the supergroup and the fault that offsets it. It does not cut the Paleozoic sedimentary rocks.
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edge Member (Idle past 1736 days) Posts: 4696 From: Colorado, USA Joined: |
No I don't know what you mean by "formed by erosion." I was focused only on the form of the strata.
They were formed by erosion just as the shape of the Supergroup rocks was.
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Faith  Suspended Member (Idle past 1474 days) Posts: 35298 From: Nevada, USA Joined: |
The unconformity cuts both the bedding of the supergroup and the fault that offsets it. It does not cut the Paleozoic sedimentary rocks. That is correct. What's your point?
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edge Member (Idle past 1736 days) Posts: 4696 From: Colorado, USA Joined: |
Erosion will do for my scenario, don't need shearing. But what do you mean by "at the base of the Tapeats?" IN the Tapeats or below it? Offhand "derived from the Supergroup and the Vishnu" sounds like a confirmation of my scenario.
So you agree that erosion of the Supergroup occurred before the Tapeats was deposited on the unconformity? How do sedimentary clasts of the Supergroupat the base of the Tapeats support your position?
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edge Member (Idle past 1736 days) Posts: 4696 From: Colorado, USA Joined: |
That is correct. What's your point?
The unconformity is younger than the Supergroup and the faults that offset it. But there is no evidence that it is younger than the Tapeats.
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Faith  Suspended Member (Idle past 1474 days) Posts: 35298 From: Nevada, USA Joined: |
No I don't know what you mean by "formed by erosion." I was focused only on the form of the strata. They were formed by erosion just as the shape of the Supergroup rocks was. I have no idea what you mean. Surely the Rockies were formed by the upthrusting of the strata wherever the strata are the prominent feature. I'm sure there has been plenty of erosion as well, but what point are you making about this? Erosion didn't FORM the mountains, the upthrust rock did. Edited by Faith, : No reason given.
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Faith  Suspended Member (Idle past 1474 days) Posts: 35298 From: Nevada, USA Joined: |
Erosion will do for my scenario, don't need shearing. But what do you mean by "at the base of the Tapeats?" IN the Tapeats or below it? Offhand "derived from the Supergroup and the Vishnu" sounds like a confirmation of my scenario. So you agree that erosion of the Supergroup occurred before the Tapeats was deposited on the unconformity? No, it occurred as a result of the tectonic force tilting and pushing up the Supergroup, plus the horizontal movement at the unconformity between the Tapeats and the Precambrian rocks. (I've begun to use the term "erosion" to describe the rubble that accumulated at the unconformity, since you reject the terms "sheared" and "abraded" but I certainly don't mean by that word what you mean: that the erosion occurred on the surface before the strata were laid down. It would be nice to have a different word to say it, however.)
sedimentary clasts of the Supergroupat the base of the Tapeats support your position? They are the result of the collision between the lower tectonic force and the upper weight of the strata (which caused the Kaibab Uplift among other things) plus the horiizontal movement between them. Edited by Faith, : No reason given. Edited by Faith, : No reason given.
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Faith  Suspended Member (Idle past 1474 days) Posts: 35298 From: Nevada, USA Joined: |
That is correct. What's your point? The unconformity is younger than the Supergroup and the faults that offset it. But there is no evidence that it is younger than the Tapeats. The Kaibab Uplift is the main part of that evidence, since it pushed up the entire stack of strata where the Supergroup collided with the Tapeats. Edited by Faith, : No reason given.
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