Evidences Of Diverging Processes Within Tibet Mountain System.

  Navigate to "Lhunze" using a map tool, set it to "Terrain" mode. The valley spans approx 20km from West to East (and slightly from North to South). The width of the valley is approx 3km. Northern "shoreline" (so to say) of the valley reflects the southern "shoreline" quite nicely. The diverging process, I think, took place.

   The diverging process was rather local.  On further examination of Tibet mountain system we could find many other instances of a diverging processes. Could the pattern had been caused by the global process of the collision between two continents? I am not sure it could. 

   Rather, as I suggested in "Formation Of Mountain Ridges by Broken Process Of Subduction Of A Tectonic Plate." ( http://divergent-boundaries.blogspot.com/2011/05/mountain-ridges-formation-keeping-it.html ) and "Flood basalt" ( http://divergent-boundaries.blogspot.com/2011/07/flood-basalt.html ) the assembly of loosely coupled chunks of crust would react on local extension forces by performing local "forced diverging processes". Also a divergent boundary (even local one) could develop the spreading force if deformations and temperature gradient were present.

   If rifts are found along the center-line of a valley, then, I'd like to think, the diverging process was not smooth, the diverging force was partially of fully developed by the boundary itself as it was described in my previous posts. If the floor of a valley is smooth, then I'd like to think the diverging process was caused mostly by external forces.

   Talking about Lhunze, I'd like to conclude, that the position of the inclined chunks of crust within the local assembly is that, they look East (and slightly South). That is, the vector perpendicular to the plain of the piece of crust would point to East (slightly South) and to somewhat bottom due to the inclination. Recall "Reshaping Pangaea" ( http://divergent-boundaries.blogspot.com/2011/07/reshaping-pangaea.html ), the crust here went from South-East. One or two chunks (whatever fit 20km) due to local extensional forces got broken and diverged off the break-line. Neighbouring chunks, as the chunks within the assembly are loosely coupled, did not broke and did not diverge, that's why the valley developed locally. If it were the global force of the collision between two continents to form the mountain system, I don't see how the local divergent boundaries could had developed.
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Flood basalt.

1. Old crust breaks into pieces, new crust subducts under it. Magma gets locked.
   Once the subduction of the oceanic crust started, the newly spread crust is easier to get subducted compared to the crust that was developed by spreading against non-subduction borders. Current Atlantic ocean crust is not as smooth and thin as most of Pacific ocean crust. That's why when The Ring OF Fire had shrunk and the continents decided on getting back through Atlantic, the current Atlantic crust would not get subducted, it would rather be getting broken into chunks, and the chunks would take inclined position. The newly spread crust being smooth and thin would be able to get bent and dive under the chunks of old crust. The magma below the broken chunks of older crust is getting locked by the subducting plate.
2. Overlapped subducting plates uplift the locked volume of magma. 
   The Ring Of Fire is shrinking. Subducting plates are getting overlapped. One plate's performing shallow subduction, the other's doing steep subduction. The resulting deep structure is less dense than surrounding magma, thus the locked volume of magma is getting uplifted.
3. The diverging process squeezes the locked magma out.
   The uplifted ridge is getting broken by gravitation assisted diverging process due to the boundary deformations between the two plates. The diverging process squeezes the locked magma out and down from the volume. Probably The Snake River Plain could be a good example of the process. The overlapping plates had locked magma under it and had uplifted it. The thick structure of overlapped plates did not melt for quite long time and had reached as far as Yellowstone. The diverging process naturally squeezed out the magma down on both sides - Columbia river and Great Basin flood basalt. The process on the tip of the overlapped plates would cause a stream of magma and thus would be forming calderas from time to time.
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Porphyry Copper. More On Reshaping Pangaea (Gondwana).

Today's documents are:
- U.S. Geological Survey, Open-File Report 2005-1060, Version 1.0. "Porphyry Copper Deposits of the World: Database, Map, and Grade and Tonnage Models" By Donald A. Singer, Vladimir I. Berger, and Barry C. Moring, 2005. ( http://pubs.usgs.gov/of/2005/1060/ ) [Accessed Jul-22, 2011}

- NASA, Earth Observatory, "Alfred Wegener (1880-1930)" by Patrick Hughes, map on Wegener's fossil and geological evidence that the continents were previously connected ( http://earthobservatory.nasa.gov/Features/Wegener/wegener_4.php ) [accessed on Jul-22, 2011]

- "Some General Concepts underlying the Science of Geology", primary author Nicholas M. Short, Sr. , section 2, "The Rock Cycle" ( http://rst.gsfc.nasa.gov/Sect2/Sect2_1b.html ), image showing the positions of the continents from early Pangaean breakup to the Present. [accessed on Jul-22, 2011]

Only Eastern Australia is rich of porphyry copper deposits.
   On the image showing the positions of the continents from early Pangaean breakup to the present there is no porphyry copper deposits for:
- southern part of South America;
- Africa (3 deposits in Africa are too old to fit the discussed time frame);
- Antarctica;
- India;
   Only Eastern Australia (New South Wales and Queensland) are rich of the deposits. The deposits are dated according to mentioned "The tab-delineated text file containing the porphyry copper database", if I understand it correctly:
- 220-300 Mya for Queensland deposits (approx 16 items);
- 440-460 Mya for New South Wales deposits (approx 8 items);
   Also half dozen of deposits are scattered between Western Australia, Victoria, South Australia, the deposits seem to be too old to fit the discussed time frame.
   How did all items of the image managed not to develop porphyry copper and only Queensland and New South Wales got the copper during 220-300 Mya and 440-460 Mya accordingly?

Comparing the shorelines.
   Let's look a bit closer at Queensland/New South Wales shoreline using a map tool. Compare the shoreline to the Chile's shoreline corresponding to Atacama desert. Compare the Australia's fragment between Byron Bay and down to south of Port Macquarie to the Chile's fragment between Arica and down to Tocopilla. Please keep in mind, Australia may had rotated slightly since then. I can be wrong, that's just a suggestion that Australia once was connected to South America. Besides the fragment of Chile's shoreline seems to be complimentary to the mentioned Australia's fragment, Chile, as everyone know, features porphyry copper deposits not even worse than East Australia.

 The porphyry copper pattern as an evidence of the layout of Pangaea.
   I'll check Chile's deposits ages later, the discrepancy in the age can be explained by the fact that the subduction process on the western and eastern sides between diverging Australia and Chile may had initiated at different times (porphyry copper development seems to be related to the subduction process). The porphyry copper development seems to be taking time of steady subduction of the oceanic crust. The suggested by Wegener Australia's post-Pangaea trajectory seems not to fit the  picture of steady subduction process against the East Australia. The suggested in "Reshaping Pangaea" ( http://divergent-boundaries.blogspot.com/2011/07/reshaping-pangaea.html ) the Australia's post-Pangaea path seems to fit porphyry copper pattern better. 

India's almost "porphyry copper"-less status.
   Regarding India's almost "porphyry copper"-less status, India seemed to start off the Australia's North-West, that is too far from the subduction zone, and thus had had no chance developing porphyry copper.

Summing things up.
   Well, this was an attempt to prove that Australia was connected to South America at Pangaea times. Then Australia was diverged out to its current position. The diverging was accompanied with the subduction of oceanic crust under the Eastern Australia, thus porphyry copper deposits were developed. The 440-460 Mya age of New South Wales deposits was, probably, because the deposits were developed on the previous "Ring Of Fire" cycle.

Next stop - nothofagus-less Africa.
   Next attempt to prove "new" Pangaea layout will probably be to talk on nothofagus-less Africa. On Wegener's layout of Pangaea, nothofagus was found on the left from Africa in South America, on the right in Australia, and even on the bottom in Antarctica, but not in Africa. The suggested in "Reshaping Pangaea" ( http://divergent-boundaries.blogspot.com/2011/07/reshaping-pangaea.html ) "new" Pangaea layout takes care of Africa.
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Reshaping Pangaea.

   Last weeks I've been trying to approach "Basalt Flows" theme. I think, I need to step back and reshape some aspects of the big picture. The idea of this post is to rethink the separation of Pangaea into the continents and how the continents drifted to their current positions.

The documentss/tools used:
- NASA, Earth Observatory, "Alfred Wegener (1880-1930)" by Patrick Hughes, map on Wegener's fossil and geological evidence that the continents were previously connected ( http://earthobservatory.nasa.gov/Features/Wegener/wegener_4.php ) [accessed on Jul-12, 2011]

- "Some General Concepts underlying the Science of Geology", primary author Nicholas M. Short, Sr. , section 2, "The Rock Cycle" ( http://rst.gsfc.nasa.gov/Sect2/Sect2_1b.html ), image showing the positions of the continents from early Pangaean breakup to the Present. [accessed on Jul-12, 2011]

- your favourite map tool, set it to accommodate the whole World, the mode is "satellite".

Optimizing Pangaea initial layout.
   Let's have a look at the mentioned image showing the positions of the continents from early Pangaean breakup to the Present. While the Wegener's reason behind the layout is clear, we need to keep in mind that the Earth is spherical, and therefore the layout can be optimized to keep the color paths shorter and a bit more logically consistent - to minimize flora/fauna needs to overcome the high mountain systems. Just position initially on the mentioned image:
- Australia at the West of South America, the place that roughly corresponds to the current Atakama desert location, Chile.
- New Zealand - again, western border of South America, below Australia.
- India - place its cratons to western Australia.
- Antarctica - place it more North-East up on the Equator.
I am absolutely sure I am not the first who suggested the layout. I'd like to credit the first person who suggested the layout, as soon as I find the info.

Continents drift paths.
   In our approach North and South America motions remain the same to the traditional ones.
   Regarding India, Australia, New Zealand - let's have a look at Google map. Let's take a closer look at the shapes of eastern and western subduction zones. Do not the eastern and western shapes resemble each other? If the oceanic floor on the map between the shapes were cut off the map, would not the shapes fit each other? Had not the shapes been diverged out? Clearly, yes, judging by the East-West rifts on the floor.
   Wait, some would say, we can see how South America could cast off India, Australia, New Zealand, but how did it manage to cast off the "forward-running subduction zone"? Well, that's the theme for another posting.
   Now we see how the tremendous amount of the assorted stuff had been pushed towards the location now known as Tibet/Himalaya. The stuff eventually was locked by India's deep-rooted cratons, and the incoming and subducting plates had had no choice to escape the location when getting semi-molten and therefore, the choice other than to be pushing up the gigantic cluster of mountain systems.
   Antarctica and later, the divergent Indian ocean floor blocked the mentioned above stream of the assorted stuff from propagating westward to Africa.
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edited Aug-17, 2011.

Static volume of hotter magma under the crust is likely to be the effect of the process in the above crust.

   One of the next posts will be on Basalt Flows. The post is expected to be somewhat lengthy. To make it shorter let one concept to occupy separate (this) post. The concept relates to the previous post "Ridge Push, Or Bridge Over Troubled Magma." ( http://divergent-boundaries.blogspot.com/2011/05/ridge-push-or-bridge-over-troubled.html ). Basically it's about what's the cause and what's the effect - static hotspot or the processes in the crust.

   Traditional Plate Tectonics tells us that basalt flows are the products of the mantle plumes (hot spots). As for me, there are some issues with the concept. Should some hot (and therefore less dense) plume occur in the mantle depth, it wont be upwelling by shortest path. Instead, as the Earth is rotating, the Coriolis effect would make the path to be very curvy, and as the velocity within the stream varies greatly, the stream would get "blurred", that is, it would have to get mixed with the magma it penetrates through.

   In other words the plume stream (should it occur) has to mix with magma it gets through, and the length of the affected area has to be comparable to the distance the stream had made, that is it has to stretch by thousands kilometers. The temperature within the volume will be only slightly higher than the temperature of the neighboring magma. And, instead of trying to penetrate the crust, the volume would rather keep on its movement.

   In other words, if the volume is not moving, then the hot spot's nature has nothing to do with magma depths. Its nature belongs to processes that are taking place right in its ceiling - oceanic crust. Again, in other words, static volume of hotter magma is unlikely to be the cause of what's happening with crust, rather the static volume of hotter magma is likely to be the effect of the process in the above crust.

    I think, more practical research should be held on the hot spots. The articles below, as for me, cast some doubts on Hawaiian volcanoes to be the effect of a mantle hotspot.
MIT News, "Hotspot in the hot seat. New seismic imaging alters the picture beneath Hawaii" by Jennifer Chu, MIT News Office, May 27, 2011. ( http://web.mit.edu/newsoffice/2011/hawaii-hotspot-0527.html )
Science, "Another Look Beneath Hawaii Knocks Islands Off Their Riser Pipe" by Richard A. Kerr, 26 May 2011. ( http://news.sciencemag.org/sciencenow/2011/05/another-look-beneath-hawaii-knoc.html )

   The assumption that "static volume of hotter magma under the crust is likely to be the effect of the process in the above crust" is crucial in many Plate Tectonics topics, to name a few: the mechanism behind the diverging boundaries, intraplate diverging processes, basalt flows, some types of calderas (Yellowstone), etc.
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edited: Aug-17, 2011

Diverging Processes Within Las Vegas Valley.

   Let's navigate to Las Vegas. Set the map to "Terrain" mode. See the part of Las Vegas Valley between North-West of Las Vegas and Indian Springs which is further North-West approx 50km. Would not north-eastern mountains of this part of the valley fit south-western mountains if the part of the valley were cut off the map? I'd say, yes. If the depths of the mountains were found of different stuff and age than the depths of the valley floor, then the mountains were diverging. The valley's floor, I'd expect to be of magmatic nature that a divergent boundary usually consist of. The mountains I'd expect to be gathered of chunks of older oceanic crust and therefore even at the depths they should show all the usual oceanic floor features.
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Diverging The Southern Death Valley.

   The reason for the examination of the Snake River plain in one of my previous posts was to get a clue to processes behind Yellowstone caldera and a clue to forces that are global to the west of NA and are parallel to the coastline.

   Now, why not to search for other possible examples of intra-continental diverging processes? Why not to start with one of the most famous US valleys - Death Valley? Its southern part, just around the Confidence Hills seems to show a good example of the process.
  
   Navigate to Shoreline Butte, Southern Death Valley, near Ashford Junction, California State Highway 178. South to this junction are the Confidence Hills. Set map mode to "Terrain" and have a look at mountains to South-West and at mountains to North-East of the Confidence Hills. Imagine, if the part of the valley the Confidence Hills are placed on, were shrunk, the mountains would fit each other quite nicely. Thus, at least this part of the Death Valley was formed by a diverging process.
  
   That's enough for a blog post, I think. The importance of the understanding that many (if not most) plains/valleys on the west of the USA were formed by the diverging processes is hard to overestimate. Particularly it's important in rethinking the Slab Gap Hypothesis, but let's leave it to another blog post.
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The Snake River Plain As A Divergent Boundary. Yellowstone Caldera.

   Let's take a look at The Snake River Plain satellite photo at: OSU, "The Snake River Plain and the Yellowstone Hot Spot" ( http://volcano.oregonstate.edu/vwdocs/volc_images/north_america/yellowstone.html ) [Accessed Jun-18, 2011]

   Let's consider Eastern part of the plain (the one that is closer to Yellowstone). Interestingly, for this part of the plain, its North-West border would fit exactly South-East border if the plain between borders gets cut off the image. And, as the ridges are very diverse in their shape on a distance even much less than width of the plain, the only explanation of it, I can think of, can be the divergent boundary formed perpendicular to the ridges. Assuming the divergent process is 1sm/year, it would take approx 10 million years to spread the plain. The divergent process may have stopped long ago for most of The Snake River Plain, but apparently not for its North-Eastern tip.

   It woud be very interesting to compare the plain's crust and relief to some oceanic (Pacific) divergent boundary's crust and relief. I've looked through approx a couple of dozens .gov and .edu sites on The Snake River Plain, - none of the sites mentioned that the borders of the East of The Snake River Plain would fit each other. Am I missing something?

   The possible scenario for Yellowstone Caldera can be that the divergent boundary had been developing pressure and trying to build its "Bridge Over Troubled Magma." (see http://divergent-boundaries.blogspot.com/2011/05/ridge-push-or-bridge-over-troubled.html and http://divergent-boundaries.blogspot.com/2011/06/tectonics-types-of-heat-transport-to.html ). As the process is relatively local (in comparison to oceanic divergent boundaries), it can't develop the force to break the plate and move its parts apart. Instead, the process would be pumping the top layer of the plate up. If the magma finds its way to escape the chamber, the volcano won't erupt.
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(edited Jun-20, 2011)
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Tectonics. Types Of Heat Transport To Develop Calderas, Volcanoes, And Divergent Boundaries.

   First two types of heat transport are obvious (let's not consider radiation heat transfer): heat conduction and convective heat transfer. And the third type is as described in "Magma Transportation On The Temperature Gradient" http://divergent-boundaries.blogspot.com/2011/05/magma-transportation-on-temperature.html

   Third type of heat transport explained.
   The concept of the third type is: Powered by deformations, crust propagates magma in the direction of lower temperature by the means of earthquakes, the magnitude of the earthquakes depends on many factors, among them are: amplitude and frequency of the deformations, crust characteristics, magma temperature, the value of the temperature gradient.

   Many would disagree on the third type. But is not it just a second low of thermodynamics in action? The first two types of heat transport move heat in the direction from higher temperature to lower temperature. Does not do the third type the same, though in its own way?

   No magic, if we have a transition zone between colder solid stuff and molten the same stuff, then, if we apply some chaotic action around the zone, the mother Nature has no choice in its response, other than moving the zone in the direction to colder stuff according to the second low of thermodynamics.

   Of course, the moving of the transition zone causes counter-action: say, gravity can be trying to get the molten stuff back. But don't we know from seismic observations that the magma is pumped up not in the form of some kind of a pipe, but rather in the form of scattered chambers? This way a local deformation has to pump magma between only neighbor chambers. Thus, regardless (almost) of the height of the vertical path, the local force of the deformation needs to be just enough to move magma to a neighbor chamber.

   The more chambers along the vertical path, the greater total force is to be applied. The divergent component of the force has to be compensated, say, in the case of divergent boundaries by subduction counter-force on the opposite side of the plate. The greater counter-force, the higher will be the ridge to build the divergent force to balance the counter-force.

   Calderas.
   The third type of heat transport can supply heat and develop pressure on its own with no help from hot spots and plumes.

   The concept of caldera development can be the next:

   - Some inter-plate or an intra-plate instance of the third type of heat transport mechanism is set up.

   - The transition zone on its way to surface meets some horizontally stretched irregularity that helps the transition zone to spread horizontally and blocks (at least for some time) the transition zone from moving up.

   - In the case the irregularity is air, magma is uplifted into the chamber, and we may assume the transition zone is the surface of the uplifted magma, no pressure in the chamber is developing yet. When magma fills the chamber, the transition zone is spreading further (including upward), pressure develops within the zone.

   - In case the irregularity is not air, the transition zone is spreading horizontally, the pressure is developed within the zone.

   - Further a number of scenarios can be suggested:

   Scenario 1. Uplifted magma and molten stuff finds its way out of the chamber forming a volcano outside the area. The pressure drops,  the top of the chamber collapses either at this time or when heat transport stops, say, for the temperature gradient disappeared and the uplifted magma and molten stuff gets down under the plate.

   Scenario 2.  Heat transport is intense and underlying plate is rather thick to maintain high pressure within the transition zone for a long time. There should be created a transition zone chamber between bottom and top plates. The top plate is strong and uniform to let the transition zone propagate uniformly upward within all the chamber area. The propagation, I'd expect to be heard as constant "roaring" as it effectively is a flow of micro earthquakes. When the transition zone is close enough to surface, the chamber blasts, the molten and semi-molten stuff of the chamber gets into air. As the chamber width, I'd expect, could reach a number of plate thicknesses, the amount of the stuff brought into air can be tens, if not hundreds cubic kilometers.

Volcanoes.
   The transition zone on its way to surface may meet relatively small horizontally stretched irregularity on no irregularity at all. In the latter case I'd expect the transition zone to uplift magma peacefully. The crust deformations would uplift magma until temperature gradient vanishes.

   In the case the transition zone meets some irregularity on its way to surface, the chamber is created. The chamber can store energy in the volume of compressed magma, in the form of compressed gases, in the form of elastic deformations of adjacent crust, etc.  So, when the transition zone finds finally its way to surface, the stored energy helps considerable amount of the transition zone stuff to blast up into air.
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   The important point about third type of heat transport mechanism is that it is heat transport mechanism, not exactly magma transport mechanism. Not much deep layer magma is expected to be among the uplifted stuff. And, the distribution of the uplifted stuff per depth it was sourced from, could be figured out. The precision of the estimations is important in crust's deep layers research.
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Broken Subduction To Cause Earthquake And Tsunami.

   Imagine an oceanic (Pacific) plate is being subducted under a continental (Asia) plate from east to west. The  oceanic plate is not totally uniform. The most notable anomalies in my opinion are divergent boundaries, active or deactivated.

   The anomalies along the most stressed part of the subduction zone may lead to the rupture along the fragment of the subducted divergent boundary. The divergent boundary is a very thin, not yet fully solidified, highly irregular, and, therefore, weak juncture between plates.

Important is that the stress within the fragment is compression / bending. The compression is caused by distant divergent boundary pushing the oceanic plate under the continental plate. The bending stress is due to the oceanic plate moving down. The oceanic plate serves as a gigantic spring to store the energy a distant divergent boundary develops under Moon/Sun induced deformations, the energy to be released in the form of the rupture. How would a compressed / bent plate broke in normal life? There will be a rupture and the ridge of the rupture would go off perpendicular to the surface.

   In our case the ridge of the rupture would go up and west. Taking into account that the fragment on the west of the rupture is more molten than the fragment on the east,  the motion will be even more to the west. This would produce tsunami to west and anti-tsunami to east.

   The dynamics of the rupture should have a prehistory which, in my opinion, can be recognized prior to the rupture. Some of the detectable properties could be:
- usual set of divergent boundary features: numerous "molten" anomalies (higher seismic wave speed) within the future rupture line, thin crust, very thin viscous layer, magma is quite high here.
- sequences of the moderate deep earthquakes by which magma propagates through the crust (See "Intraplate Magma Transport. The Concept Of Moving Transition Zone." http://divergent-boundaries.blogspot.com/2011/05/inter-plate-magma-transport-mechanism.html )
- pre-displacement under the force by the distant divergent boundary, as the zone gets hotter on average and therefore "less solid".
- oceanic water properties change due to magma having reached surface of the crust (probably could affect atmosphere as well).

   The described mechanism is heavily based on the assumption that the oceanic floor spreading mechanism is fueled by magma solidifying in the crust ruptures caused by Moon/Sun induced crust deformations (see "Divergent Boundaries Spreading Mechanism By Magma Solidifying In The Crust Ruptures Caused By Moon/Sun Induced Crust Deformations." http://divergent-boundaries.blogspot.com/2011/05/divergent-boundaries-spreading.html ).
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Formation Of Mountain Ridges by Broken Process Of Subduction Of A Tectonic Plate.

   Generally accepted theory on Himalaya/Tibet formation is the collision between two continents. Tremendous forces are believed to had applied to the continents to form the mountain system. But, can other mechanism be suggested, the mechanism to demand less energy/forces to create the mountain system? Let's try to suggest one.

   When an oceanic plate is getting subducted, what would happen to a divergent boundary on the subduction? The divergent boundary is a very thin, not yet fully solidified, highly irregular, and, therefore, weak juncture between plates. The bending stress of subduction would just cut loose the subducting chunk of the plate. The loose chunk would pop-up along the viscous border of the continent to form a mountain ridge. Other divergent boundaries and, probably, other irregularities in the plate would add more ridges to the continent.

   I'd like to think, "The Ring OF Fire" systems of ridges and some other systems were created by the mechanism described above. To check the concept let's take Himalaya:
   1. Himalaya system is quite close to the point of start/collapse of The Ring Of Fire (see "10. Persistent location of the point of start/collapse of The Ring Of Fire " http://divergent-boundaries.blogspot.com/2011/05/continental-formation-and-evolution_18.html ) Thus, we would expect all the oceanic crust to go here mainly from the center of The Ring Of Fire, that is from South East. So, the boundaries' butt ends, I'd expect to look in South East direction.
   2. The deep anomalies should align in the same SE or NW direction.
   3. Magnetic anomalies of mountains along a ridge should maintain similar alignments.
   4. The ridge system should look paradoxically young, as exposed are only newly formed boundaries' butt ends.
   etc etc.

   The ridge systems of the described nature, I would expect, could be found far from a continent's borders as The Ring Of Fire is developing many cycles, adding more area to the continent on each cycle.
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Continental Formation And Evolution Revisited.

1. Appearance of the plates. 
   Liquid Earth cools enough to let the stuff with the highest melting temperature to solidify. The denser than magma stuff is moving down to form Earth's solid core, the less denser stuff is popping up to solidify on the surface.

2. Appearance of divergent boundaries. No subduction yet.
   The solidified stuff on the surface is getting deformed by Moon. Moon induced deformations are giving birth to the divergent boundaries ( see http://divergent-boundaries.blogspot.com/2011/05/divergent-boundaries-spreading.html ). And we assume that plates are moved by the forces that originate within the divergent boundaries. The legacy concept of asthenosphere is not used, plates now own their viscous bottom. The process of subduction is not started yet anywhere within the plates.

3. Subduction started.
   The compression between plates is getting greater and ridges over the boundaries are getting higher. At some point, most probably near Equator, a newer, therefore thinner and denser plate started subducted by older, thicker, and less denser plate. It would be natural to expect Moon to trigger the process in East-West direction, that is, the "first" subducted plate to move from East to West. The subducting plate disturbs the bottom viscous layer of the upper plate pushing the roll of viscous stuff ahead. Plates subducting from different directions are creating a lens of viscous stuff under this construct of plates.

4. Proto-cratons creation.
   The process of subduction is very intense at this point. The plates with melting temperature higher than current temperature of magma are getting semi-molten. The semi-molten stuff under the plate is getting penetrated by newer subducting plates. The newer plates have lower melting temperature. Eventually they may get molten. And trapped within the much more viscous stuff they would look like huge anomalies with higher seismic waves speed surrounded with the less molten stuff of lower seismic waves speed. The resulting thick constructs may, therefore have less dense and much more solidified bottom than its middle layer. This effectively would lead to almost absence of the so called "asthenosphere" layer on the bottom of the construct. I'd like to call the constructs proto-cratons.

5. "The Ring Of Fire" sets around the cluster of proto-cratons.
   The cluster of proto-cratons gets too thick to maintain subduction within the cluster. The Ring Of Fire - the circle of subduction sets around the cluster.

6. Two types of divergent boundaries.
   Now and on two types of divergent boundaries are spreading the solidified magma:
-  First type, divergent boundaries that move plates towards the subduction (directly or indirectly by pushing other boundaries  towards the subduction zone).
- Second type, divergent boundaries within the cluster of proto-cratons. These boundaries move deep rooted proto-cratons. And they do the job against counter-acted subduction process. Thus, boundaries of this type develop higher ridges to gain greater force than the ridges of boundaries of first type.

7. Some types of mountains.
- Type 1. A divergent boundary creates a ridge. Then the boundary deactivates for some reason, say, the plates breaks along another fault line.
- Type 2. A divergent boundary (probably deactivated at this time) reaches subduction zone. It's hard to imagine how the ridge would go under the upper plate. Rather as the ridge interior is still semi-molten, the ridge would break along its line. The loosen chunk on the continent's side would rotate and expose its sharp edge on surface. the incoming plate would again try to subduct under it. The loosen chunk after the rotation can produce high mountain as it can go as deep as hundreds kilometers.
- Other types. A convergent and other types of boundaries between plates are beyond the scope of this posting.

8. Tibet/Himalayan creation.
   So, the creation of Tibet/Himalayan would take:
- a number of divergent boundaries on the ocean floor;
- subducting the floor against the continent to create a number of high ridges;
- pressing the messed plates with the incoming continent from the other side of the floor.
- a divergent boundary moving the continent off;
- repeating from the beginning as many times as needed;
 - placing some cratons around the area to not let the subducted plates leave the region in the molten state; the locked molten stuff will be pushing the Plato even higher.

9. "The Ring Of Fire" cycle approx 300 million years. Or a time to cast away stones, and a time to gather stones together (Ecclesiastes 3:5).
   The Ring Of Fire changes its shape as the divergent boundaries within the cluster of proto-cratons expand the cluster area. When the cluster gets all the surface, The Ring Of Fire collapses. There are no place on Earth to cheaply (in terms of energy) allocate the solidified stuff produced by divergent boundaries. So, new subduction line develops. And the process repeats from the step 3 as described above.
   Let's calculate the cycle of The Ring Of Fire, that is, the cycle the continents would get cast away and then gathered together. If we assume that opposite sides of The Ring are approaching each other at 15 sm/year, we would get roughly 40000km/15sm = 40 million meters / 0.15 meter ~ approx 300 million (years).

10. Persistent location of the point of start/collapse of The Ring Of Fire between cycles.
   It was mentioned on step 3 that it would be natural to expect Moon to trigger the process of first subduction in East-West direction.  It would also be natural to expect that the initial subduction line won't be able to move from West to East due to Moon's tidal activity. Also it can't move from East to West as the subduction has already built the continent on the West of it. In other words, the point of start of The Ring Of Fire will be rather close to the point of its collapse in the sense it will be the Eastern border of the continent again. With each cycle the continent would add more ridges to its Eastern border.
   This way The Ring Of Fire with each its cycle is adding more and more ocean ridges to Tibet/Himalayan cluster, and subducting more and more stuff under/inside the cluster's body.
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reposted from http://sukhotinsky.blogspot.com/
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Intraplate Magma Transport. The Concept Of Moving Transition Zone.

New concept of Plate proposed in the post "Plate Tectonics. Thinking Out Of The Sphere." immediately raises the question,  -  Is Transition Zone stable? What factors affect Transition Zone propagation? Can Transition Zone reach surface?

One of the specific features of the Transition Zone is that above it the solid body can respond with ruptures on the deformations, and below the Transition Zone the deformations can not cause ruptures. It was suggested that very this feature is responsible for magma propagation (see the post "Magma Transportation On The Temperature Gradient").

Now we are ready to think of Plate as a complex system of a) elastic solid body of very irregular shape and density b) viscous matter with very irregular viscosity/density/temperature/local_speed beneath/inside the solid body. If we accepted that plates are driven by divergent boundaries, then we don't need to group the semi-solidified/semi-molten matter beneath the plates into single wold-wide global class; we don't need to decouple the class from their solid hosts to invent the mechanism that drives plates.

Of course, the above is based on the "Magma Transportation On The Temperature Gradient" mechanism. The mechanism yet to be proved experimentally. The successful experiment would lead to relevant model of  Continental Formation and Evolution.

Quick search reveals that the closest in this direction were research works on shear-driven upwelling. Probably, if not limited by the paradigm of asthenosphere as separate world-wide layer, they could reach even further.

Plate being a complex system can develop deformations in its solid layer not only along lines, but also it could develop deep localized deformation induced by Moon/Sun. Such repetitive deformations can propagate Transition Zone up to the surface to form and feed a volcano.
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Plate Tectonics. Thinking Out Of The Sphere.

A problem with plates "floating" on the asthenosphere.

Wegener thought that the continents were moving through the earth's crust. Now the mostly accepted point is that continents do not move through the ocean floor. Rather, continents and oceanic floor form solid plates. And the plates move over the asthenosphere, the highly viscous layer of the upper mantle of the Earth.

But, really, don't you see the problem with the approach: a plate floats over the viscous layer, which floats over just liquid magma? We know some plates reach as far as 700km and even greater depths, and their bottom is not flat. How would such complex structure manage to flow over the highly viscous layer? The viscous stuff is not glued to anything, it would just go with the plate over liquid magma.
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Why not to suggest that both parts - solid and viscous parts are drifting over magma?

Wegener suggested that continents drift through the earth's crust, later it was corrected that entire plates "float" on the asthenosphere. Why did the science stop at this point? Why was not it suggested that both parts - solid and viscous parts are drifting over magma? I could imagine two reasons:

- Nobody risked to insist on such "revolutionary" step remembering how Wegener was treated with his much milder suggestion. Taking the step would mean that a plate owns its underlying viscous stuff and moves with it. This would effectively discard the legacy concept of asthenosphere as a physically consistent world-wide viscous layer.

- Science needed explanation how plates move. The underlying viscous stuff was magically decoupled from its upper solid host and it was suggested that the decoupled layer can transform the  interaction with underlying magma into the force to move the plate.  
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Avoiding postulates. 

I'd like to suggest that there is no need to decouple plate's underlying viscous layer. Let a plate "own" its viscous layer and move with it. Let's suggest that plates are driven by divergent boundaries as was described in my previous posts. I don't see how the suggested magma transport mechanism contradicts lows of Physics. Though I must admit, right now I can't back my considerations mathematically or experimentally. A quick search reveals that the closest in this direction were research works on shear-driven upwelling. Probably, the proposed mechanism will get attention as well.

If proven that plates are driven by divergent boundaries as was described in previous posts, then we don't need to make highly controversial postulates that feed so well the opponents of theory of Plate Tectonics. For instance, the postulate that oceanic divergent boundaries are made by some mysterious hot magma jets, the jets that don't obey Coriolis effect, the jets that can pump magma up as high as many kilometers.

We don't need to postulate that plates are driven by some mysterious magma flows, and driven not directly, but rather by means of separate world-wide layer - Asthenosphere. Instead, we could assume that everything beneath the plate's upper layer belong to this plate. It's just a)solidified, b) semi-solidified magma or semi-molten another plate subducted under this plate.

Of course, the plate on its way can lose some of its less viscous stuff on its bottom by the process of magma recycling. But on average, due to the Earth being cooled, it gains more by the plates subducting process.

With the help of the theory outlined in previous posts we can explain the oldest parts of plates with the roots as down as many hundred kilometers. These parts had been subducting other plates at the beginning of the plates evolution. As magma is globally cooling, the melting temperature of subducting plates was higher than the temperature of magma of newer ages. The subducted plates just added to the bottom of the oldest parts of plates as a semi-melted stuff. As magma temperature was dropping, the underlying layers of the plates were increasingly solidifying.

A number of other postulates could be avoided as well, but, probably, it can be the subject of the next posts.
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New concept of Plate.

Probably, in the future it would not be a bad idea to rethink further usage of the concepts "asthenosphere" and "lithosphere", as the concepts don't fit well the proposed theory. The suggested new concept of Plate, I'd like to define the next layers:

1. Solid layer.
1.1 Upper solid layer - crust, can be investigated by mechanical tools.
1.2 Bottom solid layer, too hot to be investigated by mechanical tools.

2. Transition layer. Here seismic wave speed would undergo, say, 10% to 90% of its speed change.

3. Viscous layer.
3.1 Upper viscous layer, persistent to the plate on the course of, say, 10 million years.
3.2 Bottom viscous layer, participates in magma recycling process;

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reposted from http://sukhotinsky.blogspot.com/
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(edited Jun-17, 2011)

Continental Formation And Evolution.

If the concept of magma propagation in crust along temperature gradient caused by crust deformation is correct, then interesting perspective on Continental Formation is opening. Let's assume border forces are the main forces that drive continents. Then the next basic rules could be derived:
*****
- The main source of the force to move continents are ocean floor divergent boundaries.

- The main source of the force to break a continent apart are the divergent boundaries within the continent. These divergent boundaries later can start ocean floor spreading.

- The force a sub-ducting ocean floor is acting on the continent with, is much less than the force of non-sub-ducting floor. Therefore, the sum of vectors of forces acting on a continent would point the continent in the direction of its borders under which ocean floor sub-ducts.
*****

Let's go further:
*****
- If between two convergent boundaries one has to sub-duct, the more dense one would go down.

- The crust is made of the material that a) is lighter than underlying magma and b) have higher melting temperature than the temperature of the underlying magma.

- The sub-ducting crust may not necessarily melt under the continent, as current temperature of magma can be lower than the temperature of magma the old crust was formed at.
*****

The above rules lead us to a non-that-obvious mechanism of ocean floor / continent transformations:

1. Initial sequence: 
  - Very thin chunks of crust start to pop up all over the surface.
 
  - The chunks are drifted towards Earth poles by the Moon induced tidal waves.
 
  - All the surface is filled up with the chunks. Polar layers are thicker.
 
  - The chunks are merged into crust. Moon induced waves are braking the crust into big plates. The plates are getting thick enough to resist moon induced waves to overlap them. The underlying heat is blocked. Atmosphere and ocean are developing. Polar crust regions are the first continents as they are thicker and are made of lighter crust.

2. The ocean plates with the help of Moon develop divergent boundaries. The divergent boundaries stress the crust globally, the most stressed direction is East-West on Equator. The beginning of sub-ducting process is inevitable.

3. The weakest point breaks (probably with the help of some asteroid). If not with the help of the asteroid, it would probably break on Equator, as Equator crust at this time is newest, thinnest, and most stressed.

4. The sub-ducted crust around the fault line creates a continent. The crust sub-ducting under the continent borders expands the continent.  The distant divergent boundaries push the crust to the continent. The crust is getting jammed on its way toward the continent. The structure of the resulting islands I'd expect to be heavily twisted. The island are bumped into the continent's plate adding to the plate's area.

5. The two old Polar continents are moving toward the new continent, but not too fast as the diverging in North-South direction is slower than in East-West direction on Equator. Soon they enter the continent's Ring Of Fire of sub-ducting process and bump into the continent's plate, having traveled not too far. The remnants of those Polar continent's, I'd like to think, can be found in Australia and North of Canada and Greenland.

6. The line of Ring Of Fire of sub-ducting process expands to embrace the hemisphere the continent belongs to. Then The Ring Of Fire shrinks and disappears within the other hemisphere. Now again Earth's crust has no place to easily sub-duct the extra area added by newly developed crust. The divergent boundaries stress the crust. The beginning of new sub-ducting process is inevitable. Loop to paragraph 3.

7. A number of cycles of the process had passed, I'd like to think, before Earth's crust reached its current state.
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Ridge Push, Or Bridge Over Troubled Magma.

Usually Ridge Push as a boundary force, is considered to be produced by the gravity effect. Hot mantle up-wells under the ridge, and this gives a topography-induced horizontal pressure gradient.

The problem with the approach is that I can't imagine the speed of the mantle upwelling to dynamically maintain heavy rock above the floor level at hundreds meters (if not kilometers). And, as Earth rotates, it is just impossible for mantle to up-well to sea floor perpendicularly to it. Besides, it's hard to imagine the nature of topography of the upwelling line.

But, why for two these phenomena not to reverse cause and consequence? Let "Magma Transportation On The Temperature Gradient" mechanism consume magma by lifting it up hundred meters. Fresh incoming magma would create hotter region under the ridge. The resulting bridge of solidified magma over the hot magma would push off the boundaries.

(Well, the post should, probably be titled "Troubled By Earthquakes Ridge Over Hot Upwelling Magma" :-)
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Magma Transportation On The Temperature Gradient.

Why do volcano eruptions correlate with earthquakes? Which of two of the types of events are the cause and which are the consequence? Probably, one would say, crust layers collide squeezing magma up. But, really, can the collisions produce enough pressure to pump magma that high. Have a look at The East Pacific Rise, just pure magma under the Ridge, just nothing that could resemble any kind of the pump mechanism. Nothing to get collided here at first glance. New crust is getting born here out of magma, and the newborn crust is getting spread out.

The suggested concept is the next: Powered by deformations, crust propagates magma in the direction of lower temperature by the means of earthquakes, the magnitude of the earthquakes depends on many factors, among them are: amplitude and frequency of the deformations, crust characteristics, magma temperature, the value of the temperature gradient.

On the example of The East Pacific Rise, it can be Moon/Sun induced deformations on the border between the plates. The mechanism can be the next:
- When crust is stretched, its ruptures are filled with magma, when the crust is getting compressed, it can not produce the same flow of magma back, as magma had lost its temperature on heating and melting the rupture borders. The more viscous magma would try to find easier ways to escape the pressure, by, say, creating new ruptures.

This way, I believe The East Pacific Rise is being built of solidified magma.
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reposted from http://sukhotinsky.blogspot.com/
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How To Tell The Nature Of The Mechanism Of The East Pacific Rise.

There are a number of models of driving mechanisms behind plate movements, just a few to mention:

- Mantle convection model;
- Slab suction;
- Gravitational sliding;
- Tidal friction of the moon;
- etc;

The proposed in previous posts mechanism "Magma Solidifying In The Crust Ruptures Caused By Moon/Sun Induced Crust Deformations" is completely different to them. Let's see how it fits East Pacific Rise spreading.

First, under "Crust Deformations" in this case we have the process the boundary plates are getting closer/more distant with moon month cycle. Let's leave Sun and planets effects for next postings. Moon orbit is inclined toward Equator plane. Thus, Earth twice a month is more stretched on Equator, twice a month is less stretched. Because of that the distance between plates varies with the period.

Now, let us ask some questions:

- Does the mechanism pump magma up?

Yes, vertical temperature/viscosity gradient in the gap between plates acts as a pump, less viscous magma is easier to get "sucked/pushed up" when the gap between plates increases. And after cooling the "more solidified" magma under the press of boundaries would try to find "easy" way, that is, partially to up-well. If the were no vertical viscosity gradient of magma between plates, the up-welling would not be significant. The magma up-welling depends on many factors, one of them is speed of boundaries spreading. The less speed, the higher the magma could be pumped up, Mid Atlantic Ridge can be an example, in my opinion.

-What signs specific to this concept would be left on/within crust, that can be measured experimentally?

1. I think, some semi-solidified regions could be left within the spreading crust, as the squeezed up magma would not flow uniformly. With proper instrumentals the anomalies could be found relatively easy, as their depth, I'd expect, would be less than 100 km.

2. The pumping up magma should produce specific earthquake pattern in correlation with month cycle.

3. Probably it would not be a bad idea to place precision sensors on both sides of the Rise to track their relative position. If monthly relation of the distance variation is found, that can be an evidence as well of the mechanism working on the ridge.

4. Probably, there should be some properties to be detected that depend on the crust tension.

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The difference between proposed concept and models mentioned in the beginning of this post is that the models operate with force that presumably acts on a plate, while the proposed concept deals with displacement, not with force. And variable displacement between plates have to exist according to lows of Physics, the question is - is it enough by amplitude to produce the detected effect of ridge spreading. Also it should be mentioned that the the speed of the spreading is greater closer to Equator regions, that correlates with the fact that Moon's induced variations of Earth surface are greater closer to Equator regions.

The proposed idea of magma transportation on vertical temperature gradient (with the help of Moon) seems to be new as well.
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reposted from http://sukhotinsky.blogspot.com/
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Divergent Boundaries Spreading Mechanism By Magma Solidifying In The Crust Ruptures Caused By Moon/Sun Induced Crust Deformations.

This article is to formalize my previous article http://sukhotinsky.blogspot.com/2011/04/forces-behind-continental-drift.html.

Earth is getting colder. Upper parts of its molten layers have to solidify. Crust is not static. It undergoes deformations caused by Moon and Sun. Resulting ruptures have to be filled with magma, the magma within the ruptures gets solidified. Following deformations would further propagate ruptures to be filled with the solidified magma. A divergent boundary brakes the crust along the line where the crust experienced the most deformation.

If the crust was ocean crust then a mid oceanic ridge emerges, the divergent boundary that spreads crust. If that was continental crust then a continental divergent boundary emerges. The thickness of the divergent boundary increases until:
a) the boundary starts to spread crust. The boundary thickness maintains at the level just enough to spread the crust.
b) the boundary is thick enough to reduce local deformation to the level the crust forms new divergent boundary along new line. In this case deformations in old divergent boundary stop and the boundary deactivates.
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