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View Full Version : Where are the subduction zones for Africa (the topic concerns continental drift)?



preearth
2010-Jun-30, 11:30 PM
Where are the subduction zones for Africa?

http://preearth.net/africa-expansion.jpg

The quote;

"The above picture has many features that are problematic for the current theory of continental drift. For example; How can Africa be drifting east, away from the mid-Atlantic ridge, and west, away from the Indian mid-ocean ridge, at the same time? How is it that Africa is also drifting north, away from the Antarctic mid-ocean ridge in the south? Where are the subduction zones? Why are the only subduction zones found in the Mediterranean, which is to the north? How does all this spreading, east and west, end up being subducted in the north? And, why is the region of subduction zones so small, in comparison to the region of spreading ridges?

The Antarctic continent is an even more extreme example of these problems. I will not dwell on the many problems of the current theory of continental drift, but wish to point out, that the reason the African plate appears to have expanded around continental Africa, and the reason that the Antarctic plate appears to have expanded around Antarctica, is probably because they did."

from http://preearth.net/ asks; Where are the subduction zones for Africa?

So,... where are they?

This is an honest question. I have no idea where they are supposed to be.

preearth
2010-Jun-30, 11:32 PM
Also, I would like to request that the thread on "Did Earth coalesce from 2 medium sized planets?"

http://www.bautforum.com/showthread.php/104316-Did-Earth-coalesce-from-2-medium-sized-planets

be reopened. After all,... you claim that the thread was only closed while the OP recovers from suspension;

"Thread closed while OP recovers from suspension. "

Well, the OP has recovered from suspension (actually an illegal suspension according to your own rules).

Or was that just the most convenient pretext you had to close it? You certainly don't seem too keen to open it again.

jlhredshift
2010-Jun-30, 11:47 PM
It is even worse. Your map is missing "The East African Rift (http://en.wikipedia.org/wiki/East_African_Rift)"

korjik
2010-Jul-01, 12:04 AM
It is also missing all the subduction under the Mediterranean. Which also answers the question in the OP.

You really only need one subduction zone on the whole planet to keep the planet the same size.

The Pacific plate is shrinking. It evens out the growth of other plates.

Tensor
2010-Jul-01, 12:31 AM
As korjik says, it's all the subduction under the Mediterranean. It actually makes sense if the the African plate is being pushed from the East, West, and South. The only place to go is to the North, getting subducted under the Eurasian plate, just as it appears to be doing. You know, with all the earth quakes and volcanoes that happen under and around the Mediterranean.

jlhredshift
2010-Jul-01, 12:38 AM
As korjik says, it's all the subduction under the Mediterranean. It actually makes sense if the the African plate is being pushed from the East, West, and South. The only place to go is to the North, getting subducted under the Eurasian plate, just as it appears to be doing. You know, with all the earth quakes and volcanoes that happen under and around the Mediterranean.

And as korjik has pointed out the "Ring of Fire" is subduction all around.

PetersCreek
2010-Jul-01, 12:56 AM
Also, I would like to request that the thread on "Did Earth coalesce from 2 medium sized planets?"

http://www.bautforum.com/showthread.php/104316-Did-Earth-coalesce-from-2-medium-sized-planets

be reopened.

The best way to request that a thread be reopened is to report the closing post in that thread. This will bring it to the attention of all moderators.

In that now-closed thread, moderators converted your high-bandwidth images to links. You were suspended for repeatedly changing them back to inline images. Now, in this thread, you have once again posted an image that exceeds our Rule 8 image size guidelines. I'll say this: I am not inclined to reopen that thread if you're going to keep doing that.

Report the last post in the closed thread if you want other moderators to consider your request.

preearth
2010-Jul-01, 02:15 AM
In that now-closed thread, moderators converted your high-bandwidth images to links. You were suspended for repeatedly changing them back to inline images. Now, in this thread, you have once again posted an image that exceeds our Rule 8 image size guidelines. I'll say this: I am not inclined to reopen that thread if you're going to keep doing that.


Big deal. So I forgot to point to the JPEG and pointed to a larger GIF.

I have changed that.

I see no one here can give a half-way plausible reason that Africa lacks subduction zones (except for the tiny subduction zone in the Mediterranean and,.... to suggest it is all subducted there, is silly in the extreme).

By the way, although they are interesting, I do not seek your opinions. I want to know what scientists actually believe.

I want to know what the scientific establishment believes to be the case.

A link to a few scientific papers, and/or the attaching of such papers to this thread would be fine.

Swift
2010-Jul-01, 02:49 AM
Big deal. So I forgot to point to the JPEG and pointed to a larger GIF.
preearth,

Do not debate moderator comments to you in thread. And following moderator requests is a big deal and your not following them got you suspended.


By the way, although they are interesting, I do not seek your opinions. I want to know what scientists actually believe.

I want to know what the scientific establishment believes to be the case.
By the way, this is a discussion board, so it is not up to you who responds to threads. And you might be surprised, but lots of people here are scientists and/or are very familiar with the scientific explanations for things such as geology.

korjik
2010-Jul-01, 06:48 AM
Big deal. So I forgot to point to the JPEG and pointed to a larger GIF.

I have changed that.

I see no one here can give a half-way plausible reason that Africa lacks subduction zones (except for the tiny subduction zone in the Mediterranean and,.... to suggest it is all subducted there, is silly in the extreme).

I cant give a half plausable reason, only the actual reason. Sorry.


By the way, although they are interesting, I do not seek your opinions. I want to know what scientists actually believe.

Place "As a scientist" it the beginning of my post. Problem solved.


I want to know what the scientific establishment believes to be the case.

A link to a few scientific papers, and/or the attaching of such papers to this thread would be fine.

How about you explain to us why you think Africa must have subduction zones around it?

The only reason any of us can think of is that you think that a growing africa plate implys a growing total surface area for the Earth, meaning that the Earth's volume must be increasing. That is why we have responded with the subduction being on the other side of the planet in the Pacific. If the Pacific plate is shrinking as fast as the Africa plate is growing, then the total volume of the Earth is constant and things are hunky-dory.

JohnD
2010-Jul-01, 09:16 AM
prearth,
Look at any map of Pangea, and how it broke up.
The map will be centered on Africa.
Almost everything else moved away.
No need for subduction - though as above there is some.

John

preearth
2010-Jul-01, 10:34 AM
How about you explain to us why you think Africa must have subduction zones around it?

The only reason any of us can think of is that you think that a growing africa plate implys a growing total surface area for the Earth, meaning that the Earth's volume must be increasing. That is why we have responded with the subduction being on the other side of the planet in the Pacific. If the Pacific plate is shrinking as fast as the Africa plate is growing, then the total volume of the Earth is constant and things are hunky-dory.

You ain't no geophysicist. That's for sure. More of a magician.

Of course, the surface area is the problem.

A problem that you mystically make disappear by slight of hand.

Consider the mid-Atlantic ridge.

Circulating either side of the ridge are (supposedly) mantle currents.

The currents rise at the ridge and extend away from it for some distance until they descend to the depths and then rise again in a gigantic circulation.

Now the mantle currents fix the mid-Atlantic ridge.

The ridge is a fixed line (really a curve or feature, but lets call it a line) on the globe and cannot drift willy nilly as you are assuming.

Similarly, the mid-oceanic ridge of the Indian ocean is fixed by the mantle currents mechanism.

Consider the mid-Atlantic ridge as a line on the left.

Consider the mid-oceanic ridge of the Indian ocean as a line on the right.

Near each of these two fixed lines, and interior to them, you have millions of square kilometers of new surface being created.

Without subduction the extra area cannot be destroyed and the surface area of the Earth must increase dramatically, which cannot happen without an increase in volume, or something even more spectacular.

The reason you have "no problem" with all this is because you allow the ridges, in fact, the whole mantle currents mechanism, to drift.

You allow the machinery that causes drift, to itself drift.

What mechanism do you hypothesize to allow this drift of the drift machinery?

Of course, it is a nonsense to allow the drift machinery, to drift.

So,... do you now see why one expects subduction?

jlhredshift
2010-Jul-01, 11:11 AM
As you wish:

Results from GOOGLE Scholar (http://scholar.google.com/scholar?q=%22plate+tectonics%22&hl=en&as_sdt=100000000001&as_sdtp=on).

73,000 results, so report back to us when you are done, we'll talk.

Edit to add for those that know the history of plate tectonics: The very first hit is Implications of plate tectonics for the Cenozoic tectonic evolution of western North America, by T. Atwater, 1970, 1097 cites, amazing.

Strange
2010-Jul-01, 11:18 AM
The reason you have "no problem" with all this is because you allow the ridges, in fact, the whole mantle currents mechanism, to drift.

Why do you think they can't move? They are just convection currents in a fluid. Why would you expect them to be stationary?

(Although, I am almost convinced just by the fact that you write everything in bold :))

jlhredshift
2010-Jul-01, 11:28 AM
Why do you think they can't move? They are just convection currents in a fluid. Why would you expect them to be stationary?

(Although, I am almost convinced just by the fact that you write everything in bold :))

Wait till he gets to Euler poles as described by Xavier Le Pichon, that will suck up some time.

preearth
2010-Jul-01, 11:30 AM
Why do you think they can't move? They are just convection currents in a fluid. Why would you expect them to be stationary?
If say, the mid-oceanic ridge of the Indian ocean moved away from the mid-Atlantic ridge, then the volume of the two circulating cells between the ridges will have dramatically increased. Something even you would probably agree, ain't gonna happen.

If you can explain (without subduction) where the extra mass to fill the volume comes from, then go for it.

tusenfem
2010-Jul-01, 11:31 AM
You ain't no geophysicist. That's for sure. More of a magician.



And you, preearth ain't going to attack the person. No more of these kind of comments. Only discuss the topic.

tusenfem
2010-Jul-01, 11:33 AM
Not only strange but clueless.



Stop this kind of responses, NOW! Or you will be infracted.

Strange
2010-Jul-01, 12:01 PM
Something even you would probably agree, ain't gonna happen.

Or then again, probably not. We have atmospheric patterns of high and low pressure where large masses of air move up and down by convection. These are not stationary, so I fail to see why you would expect similar phenomona in a different fluid not to move as well. Obviously, there are difference in things like viscosity and temperature differential which will chnage the behaviour somewhat (the timescales are much longer than for weather, for example) but the basic idea is the same.

preearth
2010-Jul-01, 12:14 PM
Reduced to arguing by vague analogy, I see.

"We have atmospheric patterns of high and low pressure where large masses of air move up and down by convection."

However, the main drivers of weather are large masses of air circulating horizontally. No one claims that mantle currents circulate horizontally. So your analogy is bound to be a poor one.

The question still stands; where does the extra mass to fill the volume come from?

jlhredshift
2010-Jul-01, 12:36 PM
There is not any "extra mass". All is in equilibrium except for the heat generated by radioactive decay that the Earth is very slowly losing and is what is driving the mantle convection currents.

Strange
2010-Jul-01, 12:50 PM
No one claims that mantle currents circulate horizontally.

Huh? That's how convection works. Hot stuff rises, moves sideways, cools and descends.

jlhredshift
2010-Jul-01, 01:15 PM
I think it is time we introduce you to S. Warren Carey who tried to invent the wheel you are touting. He wrote "The Expanding Earth" published in 1976.

He said in part:


"What causes the Earth to expand? My first answer is I do
not know. Empirically I am satisfied that the Earth is expanding. My
second answer is that I may not be expected to know. The answer could
only be expected to be known if all fundamental relevant physics is
already known."

Is his viewpoint mainstream, no. Is this viewpoint ATM? Absolutely!!

korjik
2010-Jul-01, 01:38 PM
You ain't no geophysicist. That's for sure. More of a magician.

Of course, the surface area is the problem.

A problem that you mystically make disappear by slight of hand.

Consider the mid-Atlantic ridge.

Circulating either side of the ridge are (supposedly) mantle currents.

The currents rise at the ridge and extend away from it for some distance until they descend to the depths and then rise again in a gigantic circulation.

Now the mantle currents fix the mid-Atlantic ridge.

The ridge is a fixed line (really a curve or feature, but lets call it a line) on the globe and cannot drift willy nilly as you are assuming.

Similarly, the mid-oceanic ridge of the Indian ocean is fixed by the mantle currents mechanism.

Consider the mid-Atlantic ridge as a line on the left.

Consider the mid-oceanic ridge of the Indian ocean as a line on the right.

Near each of these two fixed lines, and interior to them, you have millions of square kilometers of new surface being created.

Without subduction the extra area cannot be destroyed and the surface area of the Earth must increase dramatically, which cannot happen without an increase in volume, or something even more spectacular.

The reason you have "no problem" with all this is because you allow the ridges, in fact, the whole mantle currents mechanism, to drift.

You allow the machinery that causes drift, to itself drift.

What mechanism do you hypothesize to allow this drift of the drift machinery?

Of course, it is a nonsense to allow the drift machinery, to drift.

So,... do you now see why one expects subduction?

?

Why would you think that the mantle plumes are locked to the ridges?

Why would you think that the mantle plumes are fixed in position with respect to one another?

Why would you think that the increase in volume between the Mid-Atlantic and Indian ridges isnt accompanied by a decrease in volume between the Indian and Mid-Atlantic ridges? Like say the decrease in volume of the volume under the Pacific plate.

Why would you think that the East African Rift Zone dosent imply that the mantle plumes arent locked to the ridges and that the continent has overrun one of the plumes?

Considering that the entire Pacific basin is surrounded by subduction, I think that most people would expect quite alot of subduction.

PetersCreek
2010-Jul-01, 02:07 PM
preearth,

Since your question has been address and you have resumed your expanding Earth argument, this thread is closed. You may make and support your claims in your reopened ATM thread.