Question about plate tectonics

[Tatian]

Geology is just not my strong point. I was reading that there is a possibility that plate tectonics had an occasion or two where it slowed down and came to a halt for some amount of time. Can anyone tell me the names of scientists and books that subscribe and deny this claim? Very interested.

 

[juvenissun]

Geology is just not my strong point. I was reading that there is a possibility that plate tectonics had an occasion or two where it slowed down and came to a halt for some amount of time. Can anyone tell me the names of scientists and books that subscribe and deny this claim? Very interested.

There are many plates on the earth. Practically, it is possible that one or few of them were or are not moving for a while. But, in general, this should not be a concern of anything. Check the big plate of Africa. It is suggested that it hasn't moved for a long while.

 

[GrowingSmaller]

I like the Greek theory on plate tectonics:

Smashing Plates in Santorini, Greece - YouTube

 

[Tatian]

I know there are many plates on the earth. Saying Geology is not my strong point wasn't to say I don't have the most basic and fundimental of understanding of it. Additionally, I am not concerned about it being a global catastrophy, although the ceasing of tectonics would certainly be that, over a long period of time.

I want to know who (in the scientific community) is and is not subscribing about it so I can read more on this subject.

 

[thaumaturgy]

I know there are many plates on the earth. Saying Geology is not my strong point wasn't to say I don't have the most basic and fundimental of understanding of it. Additionally, I am not concerned about it being a global catastrophy, although the ceasing of tectonics would certainly be that, over a long period of time.

I want to know who (in the scientific community) is and is not subscribing about it so I can read more on this subject.

This was news to me, but sure enough, I found a link from Woods Hole Oceanographic Institute from 2008 that talks about this very topic (HERE)

It appears that two researchers (Silver from Carnegie Institute and Behn from WHOI) published a paper in Science called "Intermittent Plate Tectonics" (Jan 4th, 2008?)

Seems a relatively new concept and they use it to explain trends in the "thermal evolution" of the planet.

 

[OldWiseGuy]

If the plates do stop and start it means that they are driven by some force other than inertia or momentum. I think the molten magma is the engine of movement, driving the plates via the circulation of the magma beneath them. As the plates move the relationship between that plate and its underlying magma current changes, thus movement is altered. Perhaps some plates have opposing currents of magma beneath them which might slow or stop their movement altogether. Plausible?

 

[RocksInMyHead]

If the plates do stop and start it means that they are driven by some force other than inertia or momentum. I think the molten magma is the engine of movement, driving the plates via the circulation of the magma beneath them. As the plates move the relationship between that plate and its underlying magma current changes, thus movement is altered. Perhaps some plates have opposing currents of magma beneath them which might slow or stop their movement altogether. Plausible?

That's probably as good an explanation as anyone could give without delving deeply into technical details.

At this point, mantle dynamics are still not very well-understood. We know that the plates are moving, we know that the mantle is convecting and that there is some connection between the two, but there's still lots of disagreement about how much of the mantle is convecting, how large the convection cells are, and how exactly mantle convection relates to plate motion and other features (i.e. hot spots) that we see on the surface. The problem is mainly one of access - seismic imagery only penetrates so far, and resolution drops dramatically with depth, so there are large areas of the mantle that are almost completely unknown. And of course, we have no way to directly access the mantle. Things would be so much easier if we just had that machine from The Core...

 

[thaumaturgy]

If the plates do stop and start it means that they are driven by some force other than inertia or momentum.

Plates are thought to driven mostly by "convective cells" in the asthenosphere (the upper part of the mantle just below the lithosphere. It is thought to have a consistency not unlike silly putty as I understand it, but that's probably a gross oversimplification). In addition there's Slab Push (the high points where plates diverge at mid-ocean ridges are a bit higher pushing outward as new plate is added) and Slab Pull as plates subduct.

I think the molten magma is the engine of movement,

More generally the convective cells are related to the heat in the upper mantle.

driving the plates via the circulation of the magma beneath them.

Remember the lithospheric plates are not sitting on a sea of magma. They are setting on the more defomable, more "plastic" (plastic in the rheological sense, not as in organic material plastic) asthenosphere portion of the mantle.

Of course magma (molten rock) is formed down there too, and that's what rises up and cools to make new plate or to erupt in volcanoes as lava.

 

[juvenissun]

That's probably as good an explanation as anyone could give without delving deeply into technical details.

At this point, mantle dynamics are still not very well-understood. We know that the plates are moving, we know that the mantle is convecting and that there is some connection between the two, but there's still lots of disagreement about how much of the mantle is convecting, how large the convection cells are, and how exactly mantle convection relates to plate motion and other features (i.e. hot spots) that we see on the surface. The problem is mainly one of access - seismic imagery only penetrates so far, and resolution drops dramatically with depth, so there are large areas of the mantle that are almost completely unknown. And of course, we have no way to directly access the mantle. Things would be so much easier if we just had that machine from The Core...

Side point (since I see you here)

GSA has a field conference on the Sierra batholiths in September. Are you going?

 

[juvenissun]

I know there are many plates on the earth. Saying Geology is not my strong point wasn't to say I don't have the most basic and fundimental of understanding of it. Additionally, I am not concerned about it being a global catastrophy, although the ceasing of tectonics would certainly be that, over a long period of time.

I want to know who (in the scientific community) is and is not subscribing about it so I can read more on this subject.

I don't think there is such a person. The mechanism is more than just stop, or go. Your question is too simple to be practical.

 

[Tatian]

I don't think there is such a person. The mechanism is more than just stop, or go. Your question is too simple to be practical.

You obviously didn't read Thaumatergy's first post. Apparently it's not to simple. Besides that, there IS such a person. I told you I read about it. "The Life of Super-Earths" by Dimitar Sasselov, pg 129 par. 1 Ph.D Sasselov refers to it as part of his argument that Super-Earths would be even more likely to sustain a more healthy plate tectonics than our world would.

 

[Tatian]

Thankyou, Thaumatergy. That was interesting.

 

[RocksInMyHead]

Side point (since I see you here)

GSA has a field conference on the Sierra batholiths in September. Are you going?

I'd like to if I can get funding. Not sure if the money will be forthcoming though.

 

[juvenissun]

I'd like to if I can get funding. Not sure if the money will be forthcoming though.

Ask your advisor and give him a proposal. If he likes what you are trying to do, he may cough up some $ for you to go. For example, you may find enough info in the meeting so it may save you time and do a more efficient field work.

 

[juvenissun]

You obviously didn't read Thaumatergy's first post. Apparently it's not to simple. Besides that, there IS such a person. I told you I read about it. "The Life of Super-Earths" by Dimitar Sasselov, pg 129 par. 1 Ph.D Sasselov refers to it as part of his argument that Super-Earths would be even more likely to sustain a more healthy plate tectonics than our world would.

If you think you find a person and what he said satisfied you. That is super.

As far as Dr. Sasselov, I think he looked at things too far away in terms of plate tectonics.

 

[RocksInMyHead]

Ask your advisor and give him a proposal. If he likes what you are trying to do, he may cough up some $ for you to go. For example, you may find enough info in the meeting so it may save you time and do a more efficient field work.

'Tis already done. He's just not sure if he can scrape the funds together - I'm currently supported by the department and leftover grant money until we can get the proposal that includes my project submitted to NSF and (hopefully) funded.

 

[juvenissun]

'Tis already done. He's just not sure if he can scrape the funds together - I'm currently supported by the department and leftover grant money until we can get the proposal that includes my project submitted to NSF and (hopefully) funded.

OK, see what would God give to you. Keep it in prayer, "everyday"!