billiards

The problem for you is I do mind. I mind very much when I see someone get it so badly wrong. You still haven't even acknowledged the two very crucial points I have made: • The Parsons and Sclater (1977) thermal model to explain sea floor bathymetry (this is why you get the "mountain range" at the mid-Atlantic ridge) • The complete lack of compressional faulting on the ocean floor (i.e. no evidence for past compression -- proving your model is wrong) Those above points are real science ... PLEASE address them ... Your tactics are to shift the goal posts ... The standard model explains all the features you have mentioned easily (as I have already posted): • The valley is an extensional feature caused by the two plates drifting apart. It' a simple consequence of structural geology. You also have the same feature in the Pacific spreading ridges, the East African spreading ridge, etc. etc.. in fact generally you get basins wherever you get extensional tectonics. Now please explain why there are no compressional faults on the ocean floor, according to your model.

You "know" that there are problems with plate tectonics in the same way that a layman knows there is a problem with unifying quantum physics with gravitation. You know there are problems but you don't understand quite what they are. You're exactly the same as any crackpot who claims to have derived the theory of everything, but who can't do matrix multiplication or appreciate the power and utility of the existing theories. Hahahahahahhahahahaha. The irony, it's killing me, please stop! Hahaha! Oh dear! This is too much. Arc, the detachment zone really has no weight on this debate. Did you notice that I didn't comment at all on your model? Not everything is about you and your stupid model you know. You obviously haven't read the Parsons and Sclater (1977) paper have you? Also, you obviously have never studied any structural geology because if you had you would realise that normal faults just shouldn't be there if the ridge was formed by compression (it should be thrust faults -- which would be reactivated under extension). I have explained several times why you are wrong here, but it just doesn't seem to register. Would you like me to explain it again? No I'm afraid not. Also, playing with razors is not advisable for those that do not know how to use them safely, you've cut yourself several times.

This is deserving of its own thread: see also: New Scientist article: http://www.newscientist.com/article/mg22530074.700-mini-earthquakes-reveal-lubricant-for-tectonic-plates.html?utm_source=NSNS&utm_medium=SOC&utm_campaign=twitter&cmpid=SOC|NSNS|2014-GLOBAL-twitter#.VNObqC7p-a5 Nature News and Views: http://www.nature.com/nature/journal/v518/n7537/full/518039a.html#ref12 The Nature Letter proper: http://www.nature.com/nature/journal/v518/n7537/full/nature14146.html I have done some of my own research looking at the anisotropy in the subslab asthenospheric mantle and have found independent evidence that the slab is decoupled from the asthenosphere. Therefore, the existence of this thin decoupling channel is extremely interesting and provides a plausible mechanism for me to explain my results. It also means that the geodynamics community will seriously have to reevaluate the way they model subduction. Yes, there is a rift in the middle of the ridge. That is an extensional feature because the two halfs of the plate are drifting apart. I think we agree on that. However, your attempting to fit this into the context of your model is reminiscent of a child attempting to force a square peg through a round hole.

Figures to help explain the important concepts! Minimal text

Bobbity, perhaps it is not clear but when talking about compression we are really talking about lateral compression or crustal shortening: the type of thing arc would need when the radius of the earth shrinks. When I say where is the compression, really I mean: where is the compression accommodated? Normally the compression is accommodated in some kind of mountain belt, which is why arc points to it at the middle. Not a moot question at all.... It would have been mountains before and has since subsided. If you want to understand why I recommend studying the link I provided a few posts back: http://www2.ocean.washington.edu/oc540/lec01-3/. Of course to really understand it I would recommend reading the classic paper of Parsons and Sclater (1977) and many of the more recent follow-up papers which add new data and make incremental improvements to the model. I'll take a stab at explaining it here without the maths (the maths can be found by following the links I gave earlier). When new ocean lithosphere is formed it is initially very hot and buoyant and this gives it elevated topography forming a mountain crest at the spreading centre. As the material ages it cools, undergoes thermal contraction, gets dense and lies lower, creating the flanks of the mountain. This simple thermal model of the ocean floor bathymetry fits the data remarkably well, and also fits heat flow and gravity data. EDIT: simply no need for arc's compressive (shortening) regime. EDIT2: also the faults on the ocean floor clearly show extension (yay for structural geology) so case closed.

Yes, I thought that was what you meant. Thanks, it helps to be clear. This seafloor profile has nothing to do with compression. It is due to buoyancy. The science on this is pretty solid. You can read about it here: http://www2.ocean.washington.edu/oc540/lec01-3/ You have shown no evidence for Atlantic compression (past or present). It doesn't surprise you because you agree with me?

Good start. Put me in my place. The Himalaya is not a divergent boundary. Now who's confused? There is no EVIDENCE of past episodes of compression in the Atlantic Mid-Ocean Ridge in what you present. What you present is a red herring related to episodic mountain bulding. The rest of your argument is a house of cards, built on the shakey foundations of your imagination. I think I just heard a pot crack.

An example of erroneous extrapolation. There are plenty of examples where oceanic plates collide. Off the top of my head we have the Caribbean, Aleutian, Izu-Bonin-Mariana, South Sandwich, ... In these locations you get one (usually the older) plate subducting beneath the other (sometimes there is a respectable strike-slip component). The standout feature is the presence of a volcanic arc. Ironically, if arc knew a bit more about his own username perhaps he wouldn't have blundered this one so horrendously. This is a house of cards and a red herring.

Arc, I see you completely ignored my request to explain the apparent contradiction in your stance. Shall I take that to mean that your position is indefensible? The seafloor bathymetry is well explained, e.g. by the model of Parsons and Sclater (1977). Basically, it is higher up at the cenntre because the material is hotter and less dense. The model also fits gravity and heatflow data. So how does your model, which has not been shown to fit any data, improve on this? Additionally, the faulting on the seafloor is dominated by normal faults, try googling "abyssal hill bounding faults" if you don't believe me. These faults are ONLY formed by extension. So where is the geological evidence for compression? There is none, so how can your model fit this?

Essay, Iceland is being torn apart. There is a gaping rift in the middle of it. The land is high there because there is an abnormally large amount of volcanism at that point. Studiot, I find arc's post about as clear as mud too. Arc, please refrain from introducing more material into the discussion(!!!!!!). Please explain why in one post (referring to the Atlantic section) you say "You can see the high level of compression that it is subjected to" and in the next "There is currently no compression directly related to the mantle's subsidence in that diagram". What point are you trying to make!!?? How does this enhance your theory?

Arc, could you please explain where the compression is in this diagram. I assume you mean in the middle, but it would help if you clarify this point.

The problem with arc's "theory" is that it is only a conceptual model. The "changes" arc has made to it is simply to take the words that others have given him, like "strain energy" and to substitute them into his thesis in place of the previous less technical words. In reality, the conceptual model did not change.

Studiot, sometimes I wonder whether we are reading the same thread ... I thought we were talking about whether arc's thesis had changed at all. Here is the whole exchange as I have read it: I start with the initial criticism of arc: You come to his defence: According to that post you think arc has modified his original hypothesis. He hasn't, so I respond: Now you quote half his theory (you don't respond to my request for pinpointing the bit that has changed): Clearly I was correct. Not clear at all, so I quote the other half to show that it is still the same (the same as the theory presented recently with all the diagrams): You see that? The exact same theory written out in plain English in post #1 ... CLEARLY you were wrong! Arc's thesis has not changed! Which leads to your most recent post which now seems very out of context: Not sure how we got here, but, I think breaking up the theory and examining it piece by piece is a good idea. Subduction zones seems an excellent place to start. There are many observations that severely test the theory.

I must say I'm shocked. I expect better from a member of your standing, studiot. Arc's first post continues ... You see that? The exact same theory written out in plain English in post #1. You just didn't quote the relevant part. Did you not read that far? Or were you deliberately being dishonest? CLEARLY you were wrong! Arc's thesis has not changed! 1) Where did you refute my statement? You must have forgot to post that bit. 2) You mean if one plate goes over another and the underlying plate does not sink, then that would be "subduction"* without convection? Perhaps, but then you would have to ignore the entire scientific literature on subduction zones, for example you would have to deny the existence of a "mantle wedge". And you would have a fun (and extremely difficult) time explaining the existence of "back-arc basins". Wadati-Benioff zones might cause a few headaches, not to mention reflectivity profiles, receiver functions, and tomography from seismology. The list could go on ... * according to "a" definition 3) Good, that's one line that you have pursued, and I have been following it. (You might not have noticed but other lines of investigation have happened here too.)

Not sure if this is a deliberate straw man of if you just haven't been following closely. You got my point backwards. Subduction is contingent on mantle convection. You can't have subduction without convection, because subduction is a type of convection! Bad example. This has always been the theory and still is. The expansion of the core provides gravitational energy to explain surface dynamics. What, precisely, has changed? Of course we would like to see good science here. The subject matter of plate tectonics is fascinating to me. My contribution here is to see the gaps and pick holes where the theory is weak. However, non of my points (or indeed the points of others) has been successfully rebutted. Every single one of my points has been avoided or slammed by ignorant arguments (the earthquake catalogue debate is a good example of my points being slammed by ignorance). The subduction point is not even an attack on the theory per se (if arc accepted his model has some convection I would be happy), but again it has been slammed by ignorance. If this is science then you can take my PhD away from me because I obviously haven't understood it.

I could be more clear. A) Subduction is a mode of (mantle) convection. (Arc will disagree, but there is no science to debate here, this statement is completely uncontroversial fact.) B) Arc's model incorporates subduction. Combining (A) and (B): (1) Arc's model incorporates mantle convection. However: (2) Arc claims his model has no mantle convection. (1) and (2) contradict. Therefore we have a problem. Either arc must soften his approach and admit that there is mantle convection (in his model), or he deny subduction (to his model, and therefore it loses on the spot). Moving on ... one has to question the intentions of someone who has not changed their thesis at all in the last 19 pages. He's still spewing these dodgy numbers "80,000 km of midocean ridges are supposedly producing new crust, only 30,500 km of trenches exist" despite the fact they were shot down much earlier in this thread. Arc is basically soapboxing, not taking in any of the feedback, albeit in a friendly manner. He is clearly not interested in disproving his own theory. Has no concept of what a "prediction" is, and really hasn't the foggiest idea of how to test his theory. Nevertheless he would die for it. Passion yes, science no.

The attempts to sweep mantle convection under the carpet are incredibly unscientific. A true scientist will attempt to falsify their hypothesis. Not sweep inconvenient facts under the carpet.

I must disagree. As I said in post #354: You see that it is difficult to explain subduction with "simple convection theory" and read "it is not convection". But that is your confusion, the Earth does not care whether you understand it or not. It is complex and cannot be easily explained by "simple convection theory" -- but it is still convection!

I know what it's like to be the target of someone's negative rep bombardment (eh, Unity+) ... Not nice. That said. Why should we all lose out because of that one idiot? I agree the mods should do more in these situations, and the warning points you received were a kick in the teeth, but in the grand scheme it's only a forum ... nobody cares ... Anyway you will be missed, not sure how the geology section will survive with all the nutcases running loose.

It is also worth noting that no two scientists will have the same experiences. There are many different fields and sub-fields in science, each of those have very different tracks whether they be in academia or industry, research or application. Good scientists will always be in demand and develop skills through their education that separates them from the rest. So it is a safe bet to stay keen on the sciences, and if bitten by the science bug you will never regret it.

Arc, subduction is convection. It is not a "trap". It is a cold hard undisputed fact. It is the cold, dense, upper thermal boundary layer of a convecting system becoming unstable and embroiled into the convecting mantle. It is somewhat unusual as simple considerations tend to lead to "rigid" lid planets without plate tectonics (as exampled by other terrestrial planets). I see your confusion. You see that it is difficult to explain subduction with "simple convection theory" and read "it is not convection". But that is your confusion, the Earth does not care whether you understand it or not. It is complex and cannot be easily explained by "simple convection theory" -- but it is still convection!

Hi arc, happy new year I see there is no new material here (except the cartoons), and therefore there is nothing much left to say. With regards to subduction, do you not agree that this is indeed mantle convection in action ...? Therefore if your model includes subduction, ergo it includes mantle convection. Yet the whole point of your model (I thought) was that mantle convection was not necessary for plate tectonics. Have you not hit a contradiction? How do you reconcile it?

The light bulb might have come on in your head, in my cranium though the quantum bubbles are failing to form. I guess what it makes up for in sheer niceness of idea, it lacks in scientific rigour.

I currently believe the consensus that climate feedbacks enhance the slight (1 degree per doubling) warming brought about by increasing CO2. To change my mind I would need to understand the negative feedback mechanisms that cause increase in CO2 not to lead to global warming, and those feedbacks would need to be demonstrably true from evidence.

Well that make your argument so much stronger. [/sarcasm] How about you build on your arguments rather than play side-stepping tactics? Perhaps you could lend yourself some credibility.