What about mantle plumes?

[Dymanic]

Using the immortal words of CFLarsen... Evidence?

Did you lose the context? You first introduced AGW into this discussion with this:

Example- last Friday I was watced three talks on AGW from the folks at the "no" side.

You may not agree with my assessment of how that issue has been clouded by the influence of vested interests, etc, and that's fine, but isn't there already enough bandwidth devoted to examination of that evidence without rehashing it here? Have you not seen what happens to discussions that wander too close to that black hole? I tried to limit my responses along those lines to some brief comments followed by suggestions that we not go there. I apologize for that; I see that I was unable to resist tossing my two cents' worth in just before recommending that we not go there at all. I'm willing to stipulate that the AGW quagmire represents a biased sample of "how science works", and perhaps is not entirely relevant here anyway, considering that the topic of this thread is one which is surely much less subject to the influence of vested interests and all that.

I also think you should remember where complaints against “powerful members of society, who happen to be deeply vested in certain courses of action” usually come from. Usually from pseudoscience folks and in a few cases from a small number of people whom found themselves on the losing side and for whatever reason can’t take it.

http://en.wikipedia.org/wiki/Association_fallacy

I disagree; regardless of his qualifications, I don’t think his conclusions, or that particular quote of his within the context you are applying, are the best way to describe the situation.

I'll take that under advisement. You know, his email address isn't hard to find, starting from the OP's link.

You think more money would speed the process? Do you think its being affected by politics, dogma or religion? And what if we wait and no chest-thumping happens?

That was my feeble attempt at making a joke, but if you insist on being serious, do you really disagree that the idea that nothing can travel faster than light deserves to be called "dogma"? I mean, I don't exactly worship the idea, but I do find myself very resistant to letting go of it, and very biased toward attributing the recent CERN findings to errors in measurement. Don't you?

Again, would you happen to have something better to offer than the current way scientific community does its work? Or you just doubt the whole process for whatever reason?

I'm fairly satisfied with the answer I gave the last time you asked, so I think I'll just stick with that.

 

[LarianLeQuella]

particularly in geology--we've always been a rough-and-tumble lot

derail

Was it just me, or did anyone else just have this rock tumbler image pop into their head reading this?

/derail

 

[Correa Neto]

Did you lose the context? You first introduced AGW into this discussion with this:

I am sorry, but I think you are one who lost context. I do introduced that particular piece of AGW debate because it was an example of things in science not working as they were supposed to. I have the impression you believe this (political influences, "chest-thumping", etc.) is the norm rather than the exception in science and also believed mantle plumes debate was another example. I also have the impression you think scientists as whole should be doing more. What I am trying to do is to expose my views- this is not the way things usually happen in science. I do not disagree that AGW debate has been a sad show of poor behavior from both sides. I disagree that this is the way things usually happen in science. I do not disagree some scientists could and/or should be more active. I disagree about blaming them for society’s inertia and mistaken decisions.

Seems I failed to express clearly my takes on the subject, despite citing examples such as acquiring data on (natural) seismic events and gamma ray bursts (things completely unrelated to AGW) requires time and can not be speeded too much. Note also I have never at this thread presented my position and will not do it, since its OT.

You may not agree with my assessment of how that issue has been clouded by the influence of vested interests, etc, and that's fine, but isn't there already enough bandwidth devoted to examination of that evidence without rehashing it here? Have you not seen what happens to discussions that wander too close to that black hole? I tried to limit my responses along those lines to some brief comments followed by suggestions that we not go there. I apologize for that; I see that I was unable to resist tossing my two cents' worth in just before recommending that we not go there at all. I'm willing to stipulate that the AGW quagmire represents a biased sample of "how science works", and perhaps is not entirely relevant here anyway, considering that the topic of this thread is one which is surely much less subject to the influence of vested interests and all that.

See above. I think you made a big mistake by assuming most discussions in science, such as those related to mantle plumes, follow the same standards from those related to AGW. Actually I would dare to say that what's reported by the media is not representative of most discussion on this subject among academics. And I will say it not focusing on AGW but on the way science as whole works and also on the way society as a whole works. The media seeks attention, it will not seek a bunch of academics politely discussing a subject and quite often reaching the "actually don't know, need more research" conclusion. Remember also that even when scientists provide data, interpretation and courses of action, someone else will decide if the proposed actions should be taken or not. “Don’t build houses there, it is too close to a possible natural hazard zone” the scientist will say. The next steps should be taken by whom? If the society, if the politicians ignore the advice and the houses are destroyed by a natural disaster its’ science’s faults?

I disagree with you when you say I made an association fallacy when I pointed out where complaints about against “powerful members of society, who happen to be deeply vested in certain courses of action” usually come from. Remember- I am talking about the broad picture in science. In some cases its interesting to know about the people around you and their ways. That such complaints are frequent from pseudoscientists and a few die hard folks(*) who happened to be (at least for a certain time) on the losing side, is something also undeniable. That this behavior may also indicate something may be wrong with the position of the complainer.

I'll take that under advisement. You know, his email address isn't hard to find, starting from the OP's link.

You brought that quote to support your claim that debates in geology are not exactly dialogues but bitter fights between dogmatic people. I presented arguments which I think indicate such point of view is incorrect. The next logical step would be either you presenting counter-arguments or saying “OK, point taken”, instead saying I should discuss it all with the person whose work you quoted, and quoted in a way quite close to an argument from authority. Note you just behaved exactly like those scientists you (unfairly when making sweeping statements, IMHO) criticize so much along this thread!

That was my feeble attempt at making a joke, but if you insist on being serious, do you really disagree that the idea that nothing can travel faster than light deserves to be called "dogma"? I mean, I don't exactly worship the idea, but I do find myself very resistant to letting go of it, and very biased toward attributing the recent CERN findings to errors in measurement. Don't you?

Yes, I disagree, it is not a dogma. I disagree because “nothing can go faster than light” is a conclusion reached by theoretical and experimental physics. Show something that can and it will change to “some things can go faster than light”. A scientific paradigm, yes, it is. A dogma, no.

If I believe (not the word) the faster-than-light neutrinos are probably something related to experimental set up, yes I do. But if repetitions of the experiments or new and completely different experiments show otherwise, I will say “WOW!” and start storing cash to buy a travel ticket for the Enterprise (even if will be for my grand-grand-grand-grand-grandson/daugther).

I'm fairly satisfied with the answer I gave the last time you asked, so I think I'll just stick with that.

Sorry, I went back through the thread and could not find a clear answer. Was it the part regarding more money? I wouldn’t mind having some more $$$ for my research. Yes, it would speed some of the process. However, some research areas can’t speed data acquisition beyond a certain point. Even if you give them an über supercomputer to run their models, depending on the research area they may still need a certain amount of time to gather data from natural events.

Yes, I think my research is very important. The guys at the next doors think the same about theirs. Money is limited, you know, and its flow to science is not completely controlled by scientists. I don’t think any government of the world would agree, for example, on diverting money from government propaganda or politician’s salaries to research…

Feel free to disagree with me. Just don’t expect another wall-of-text as response since I am getting pretty tired of writing them.

(*) Not all die hards are bitter whiners. Many are not, they are just convinced they are right, for whatever reasons. And make no mistake, there’s always the chance they will be proven right as soon as some new batch of data is acquired.

 

[Dymanic]

I do introduced that particular piece of AGW debate because it was an example of things in science not working as they were supposed to.

Then we're in agreement on that.

I have the impression you believe this (political influences, "chest-thumping", etc.) is the norm rather than the exception in science and also believed mantle plumes debate was another example.

I've already stipulated to the AGW debate being a non-representative sample, and not very relevant to the mantle plumes debate. I will, however, continue to maintain that science in general is never entirely free of these, and I'm pretty sure that we are at least mostly in agreement on that as well.

See above. I think you made a big mistake by assuming most discussions in science, such as those related to mantle plumes, follow the same standards from those related to AGW.

See above. I've already stipulated to that not being the case.

I disagree with you when you say I made an association fallacy when I pointed out where complaints about against “powerful members of society, who happen to be deeply vested in certain courses of action” usually come from.
[snip]
That this behavior may also indicate something may be wrong with the position of the complainer.

Then I can only suggest that you take a more careful look at the reasoning used in categorizing that method as a logical fallacy.

You brought that quote to support your claim that debates in geology are not exactly dialogues but bitter fights between dogmatic people. I presented arguments which I think indicate such point of view is incorrect. The next logical step would be either you presenting counter-arguments or saying “OK, point taken”, instead saying I should discuss it all with the person whose work you quoted, and quoted in a way quite close to an argument from authority.

Yeah, that was unnecessarily snippy, I suppose. I just thought it was important to emphasize that while that claim might reasonably be called mine insofar as I chose to introduce it to this discussion, the idea is one that did not originate with me, but with some whose credentials can be verified as having met this test: "It's the same as any other field of activity--you don't know how the members of that community interact until you're a member of that community and observe the interactions."

Yes, I disagree, it is not a dogma. I disagree because “nothing can go faster than light” is a conclusion reached by theoretical and experimental physics. Show something that can and it will change to “some things can go faster than light”. A scientific paradigm, yes, it is. A dogma, no.

When I say that "I don't exactly worship the idea [of "c" representing an absolute limit] but I do find myself very resistant to letting go of it and very biased toward attributing the recent CERN findings to errors in measurement", I'm not basing that on my own deep understanding of the theoretical and experimental physics. I don't know about you, but I couldn't step up to a chalkboard and explain in detail the reasoning behind the conclusion that "nothing can go faster than light" if you put a gun to my head, and I submit that a lot of the people who would be just as resistant as I am to letting go of that idea could not do so either. Most of us accept it because it is what we were taught. That's dogma.

Sorry, I went back through the thread and could not find a clear answer.

I consider doubt to be the most vital aspect of the process.

If we're talking generally about "the whole scientific process", then the ability of that process to doubt itself -- its preconceptions, assumptions, biases, methods, conclusions, etc -- are the very foundation. Lacking that, data are worthless. At best.

Feel free to disagree with me. Just don’t expect another wall-of-text as response since I am getting pretty tired of writing them.

Again I must apologize, this time for not having expressed my appreciation for the time and effort you devoted to composing those posts, which I read with interest and found quite informative. If you find the inspiration to compose more of them, I'll read those too. If not, I'll understand, and I won't asssume that you simply withdrew because you found yourself overwhelmed by my superior arguments. It might save some time if we quit arguing over stuff we already appear to agree on.

 

[Travis]

I must ask something......it seems to me, from what I was reading, that the chemical composition of the basalt in the Large Igneous Provinces differs greatly from other forms of igneous rock. Wouldn't the plume model explain that?

And what is the explanation for that if not the plume model?

 

[Correa Neto]

Well, I'll try to explain it on a simple form and if I fail and say something wrong, I hope Volcano might correct me. Basalts will be basalts but there are a number of different basalts and the same is valid for andesites, rhyolites, etc. The rocks will be different but not that different. The differences will be on some (major and minor) element ratios and REE signatures, for example. There are a number of graphs to separate them based on the chemistry and link them to tectonic environments.

Now, the key is that each of these varieties are present (or more common) at certain tectonic environments. Some will need a deeper source (the place that will generate the magma, by partial melting), others a shallower one, some others a certain special type o rock and so on. This is what allows the separation of continental x oceanic basalts based on their chemistry, for example.

To this you must add the fact that the word "plume" is not very well constrained and might mean a (small) number of different things. Large plumes, small plumes, created by two convection cells with opposing circulation directions, triggered by a mantle avalanche, a "jet" of hot material from the deeper parts of the mantle, etc.

So, all you have to do is to propose something other than a plume (or another type of plume) generated the melting. Sure, its not that simple but this would be the basic reasoning you would have use to attribute LIPs to something other than mantle plumes.

 

[volcano]

Well, I'll try to explain it on a simple form and if I fail and say something wrong, I hope Volcano might correct me. Basalts will be basalts but there are a number of different basalts and the same is valid for andesites, rhyolites, etc. The rocks will be different but not that different. The differences will be on some (major and minor) element ratios and REE signatures, for example. There are a number of graphs to separate them based on the chemistry and link them to tectonic environments.

Good summary, Correa Neto. Like you said, there is a lot of variability in basalts. Many different tectonic environments erupt basalt-- mid-ocean ridges, plumes, subduction zones, etc. Basalts that come from the upper mantle are slightly different from basalts that come from deeper in the mantle. The basalts at Large Igneous Provinces (LIPs), and many of the basalts that erupt at places like Hawai'i (and other places where we think there are mantle plumes) appear to come from very deep in the mantle. LIPs, in particular, have a geochemical signature that suggests that they come from deep, hot mantle.

 

[Travis]

What mechanism, besides something akin to a plume, would allow for basalt from deep within the mantle to erupt in such great quantities?

 

[Correa Neto]

Depends on the shape of the area affected by the LIP. Wide linear area, two opposing convection cells could be "blamed" (sure, one could say the generated a plume). I also believe it may be possible (but perhaps a bit far-fetched) to put the blame on Mame decompression by upper mantle and lithosphere stretching.

If the area is a point, a blotch, well... A hotspot, which would be a long-living narrow plume.

 

[volcano]

The issue of Nature Geoscience that just came out today is focused almost entirely on ocean islands (and how they relate to plumes). This line from the editorial sums it up quite well:

So, looking at research from the past few years, it emerges that the “plume versus no-plume” debate may be ill-posed. Instead, as argued in the Feature on page 816, a more differentiated conceptual model could be more feasible, allowing for a variety of formation mechanisms for different types of seamounts and island chains. The question is not so much whether plumes exist, but in which locations they best explain the observations.

 

[volcano]

I also believe it may be possible (but perhaps a bit far-fetched) to put the blame on Mame decompression by upper mantle and lithosphere stretching.

This (upper mantle decompression) works in some areas, but many of these "plume" regions erupt lava of a composition that couldn't be produced in the upper mantle. So we think it's got to come from deeper in the mantle.

ETA:

What mechanism, besides something akin to a plume, would allow for basalt from deep within the mantle to erupt in such great quantities?

Just to clarify, keep in mind that the material ascending through the mantle probably isn't "basalt" until it's really shallow. At the depths that we think this material starts ascending, it's a solid, not a liquid-- more like silly putty than like magma. It starts melting as it ascends, and when the mantle melts, it makes basalt.
Which reminds me of this somewhat-crazed retired geologist who stormed into my undergraduate petrology class and demanded of us, "WHADDAYA GET WHEN YOU MELT THE MANTLE?!" We stared blankly, not sure if this was the opening line to a joke or a legitimate question. He followed up with "Do ya get CHICKENS?!" Now, many years later, I think of chickens every time someone talks about mantle melting.

 

[Silly Green Monkey]

Could the hot spots be the pivot points of continental plates?

 

[volcano]

Could the hot spots be the pivot points of continental plates?

Unlikely, but a neat idea. The tectonic plates (remember that some are oceanic, not continental) have changed direction a number of times (notice how the chain of Hawaiian Islands and Emperor Seamounts has a kink it in-- that's a result of a change in plate motion, and seems to imply that hot spots are relatively fixed in place, at least compared to the scale of plate motion). As plate motion has changed, there doesn't appear to be a fixed pivot point for any individual plate. Also, remember that Iceland sits on a plate boundary and also appears to have a hotspot right under it-- so the pivot point model wouldn't work for that one, either, although it'd be cool if such an elegant explanation existed

 

[Travis]

Interesting the mysteries that lay right beneath our feet still.

 

[Skeptic Ginger]

Rare View Reveals How Earth's Crust Forms

The study supports one of the dominant theories (the passive flow model) of how mid-ocean ridges work, the researchers said. Earth's crust is like a giant conveyor belt, with plates spreading apart at mid-ocean ridges and diving into the mantle for recycling at subduction zones, Key explained. The plates ride on giant convection cells in the mantle, but mid-ocean ridges aren't linked to these massive swirls. Instead, the ridges' localized melting comes from the space created by slip-sliding tectonic plates, geologists think. However, there's ongoing debate as to whether the driving force is pull at subduction zones — the passive flow model — or push from magma coming up at ridges. "Our data looks just like the passive flow model," Key told OurAmazingPlanet. "It agrees with what everybody thinks should be going on, but we haven't had a good image before. It looks like something somebody would have drawn in a textbook based on what we thought was going on."

I can't find the thread I said something about pulling vs pushing the plates in but I believe I didn't explain the concept very well. This article on a new study published in Nature explains what I was trying to say.