The origin of mountains

Mountain building - the Origin of Mountains
(...or, what is a mountain belt?...)

Fig.1. The mountain belts of the world as a single continuous circumglobal loop. From the Alps through the Zagros and the Himalayas, the present-day mountain belts encircle the world as one continuous loop dilated in the Pacific region about the greatly distended Indonesian pivot of the Western Pacific to the west and the 'unhinged' Caribbean pivot to the east.

What is a mountain belt (?)   ...Is not a good question, because the use of the indefinite article 'a' implies there are, or may have been, numerous mountain belts, i.e., that 'mountain belts' (plural) are an item to be considered in the history of geological dynamics, when the evidence in fact is that there is only - and may have ever been only - one. So the question should not be, "What is a mountain belt?" (implying plurality and hence a number of different sources from which to glean an answer to the question), but what is the mountain belt (singular) all about?
The mountain belt? Yes, ...the one in the picture, ...the one that used to go all around the Earth as a simple equatorial loop - and still does (sort of). And appears to be the only one that ever was - at least within 'living geological memory'.
This might come as a surprise to anyone used to plate tectonics' idea of the way that mountain belts are thrown up by plate collision, but I bet not half the surprise it was to me to have to contemplate it in the first place. I used to think, probably like you, that.. ... - well, not really 'think', because it was what I was told (and read) - that mountain belts were ten-a-penny in geological history, and that they got thrown up by the compressive forces in the crust as great slabs of Africa-like juggernauts pushed and heaved against other slabs of Africa-like crust, and that as it heaved here it was pulling apart there, ...and that they (the mountains) got eroded and all the erosional debris went into the somewhere-else- pulled-apart bits, which were then basins that accummulated all of the erosional debris and that's how the basins got filled up with sediments and then it was the basins' turn and they got uplifted because somehow the stresses in the crust changed and instead of those Africa-like juggernauts going "this-a-way" (to compress the crust and throw up mountains) they changed direction and went "that-a-way" instead (to form a basin) (and a mountain belt somewhere else),... and so on.
See? How it all nicely rolls off the tongue of geo-logic?    In fact the way the stratigraphic sequence stacked up it could not only go this-a-way and that-a-way, but go into reverse as well ! And, stratigraphically speaking, all at the drop of a tectonic hat! All fantastic stuff and a tremendously fertile area for much speculation and research. Trouble was, once you really looked at a mountain belt, a real one that is, and not an imaginary one that you could conceive from fiddly folds in outcrop, but a real one like you see at the present day, it was really, really, really BIG - much too big to be caused by a bevy of plates moving (independently about) here and there. It wasn't just something that happened from time-to-time right here and over there, ...it went on and on and on - right the whole way from the Atlantic to the Pacific, and then right around the Pacific - and if you closed the Atlantic you could see that it linked up with where you started. In other words, it was something that kept going on, and was some size!   Much bigger than the conceptualisations invoked from outcrop or even regional complilational studies by teams of researchers.
One continuous global mountain belt? How come? How is it possible that all these supposedly independently moving plates can get their act together to push up one continuous mountain belt, ...that goes all around the world, ...in a loop, that when you reassemble it is more or less ambital to the Earth?   What's going on?   Was all the crust drifting from the poles to the Equator, or what? And if so, why?   And where do 'plates' ("the Earth being divided into about twelve or so major ones of them (and lots of smaller ones)") - fit in?
Well, enough of that, because I know someone is going to say, "but what about the Hercynian and the Caledonian orogenies, and the Urals, and the Appalachians, and so on". But the point is, ...that once you look, ...once you really look, ...once you really, really look (and think about it at the same time), the overall pattern of global deformation links these to the same mountain belt - as precursors that have been detached from their original location in the same way that the present circumglobal mountain belt has been detached form its original location - namely the Indian Pacific spreading ridge . That is, the Palaeozoic and Hercynian mountain belts and the present day mountain belts are the same mountain belts, and are the expression in the crust of the now exposed spreading ridges in the mantle.
And this is the really interesting part - that mountain building seems not to be a haphazard affair that happens here and there due to vagaries of movement of independent crustal plates, but the whole lot of them (mountain belts - as we best know them) appear to be linked in space and time as a single continuous building event that completely overrides any notion of independent plate collisions.   And what's more, (once the retrofits are made) an event that was ambital on a smaller Earth.
...The ambital mountain belt that culminated in a dilating split to give the Pacific and oceanisation of the crust, whereupon the mountain building ceased.
Ceased?   Well, not exactly.    Well, ...yes, ...it did cease - in the continental crust, ...virtually, at any rate, but not in the growing axial split that penetrated the mantle, which was to become the largest mountain 'belt' on the planet, namely the Pacific ocean. It's just awfully wide and (like Mount Everest and the other high mountains of the world) very flat-lying.   It is a huge 'plateau' of mafic rock standing above its subcrustal mantle 'floor', with the spreading ridge of the East Pacific Rise being its actively rising axis. Its fossil remnant in the continental crust (the circumglobal mountain belt loop - brown in the figure) is being eroded down. Eventually this mountain belt will come to stand as the highest tracts on the planet as the continents are further eroded and the ocean floors come to stand above sea level as the oceans recede as the Earth continues to increase in size.
And that is what THE mountain belt of the world is all about.   It is the Pacific Ocean, ...the active axial core of the same mountain belt that we see in the crust.   Some mountain belt? Sure is.   The real laugh is that in plate tectonics (the Acne of Geological Thought), the only plate collision that gets a mention these days as throwing up a mountain belt is Little India, with its battering-ram-like horns, making those two great big dents in the Himalayas. Africa, with the spreading ridge of the Red Sea and the failed rift of the Persian Gulf in between it and Europe - as well as of course the extensional zone of the Mediterranean - has become just too difficult for Plate Tectonics to comment on, ..and so it doesn't any more.   India is the only continent that ever gets a mention as colliding with anything to throw up a mountain belt.   Little India? Collision? Mountain belt? Horny Little India! ... Plate Tectonics, ..what a laugh!

See what Little India did? ... With its 'horns'?   Not only did it shake the whole of Asia right to its oriental back teeth, spinning off Mongolia and the Russian Peninsula and detaching the Americas and knocking them to Kingdom Come, but also it scissored them right open and unhinged them to allow the Pacific to intrude two thirds of the Earth's surface!   And not only that, but ripping the crust right off the Oceanic spreading ridge and dragging Australia away from India. Some shunt!   Now that's Far-Field Tectonics for you - plate tectonics style.   Google it up and have a laugh - 'far-field tectonics"? Indeed! Pteros, you have to hand it to them for unparalleled nuttyness.

Fig.2. Major crustal pivots of the Pacific distending the Pangaean circumglobal mountain belt loop, the Indonesian-Siberian pivot on the western side, and the Caribbean pivot on the eastern side (schematic only).     The Mediterranean region is the hinge.    (See also 1, 2, 3, )

So why do Pteros say the spreading ridges are the biggest mountain belts on the planet? It's true, they do, ..and they are. But what plates push *them* up, if mountain belts are due to plate collision? Also, where are the India-equivalent, continental battering rams that pushed up the circum-Pacific mountain belts?