Laspi, Crimea.
Have you ever been to one of the most incredible places on the Earth - Laspi, Crimea, Ukraine, the place where the mountain ridges turn from parallel to perpendicular to coastline direction, and then abruptly end up with 600+ m vertical walls? Search images with "Kokiya Kaya", "Kush Kaya", "Ilyas Kaya" to get the impression of it (try views from the sea). Can a mountain ridge be formed the way it would end up with a vertical wall on its side? Unlikely, I'd say. Rather, I'd expect some tremendous force to break the ridge, and then to diverge one part of it from another over hundreds kilometers.
The driving force of the process, Shatsky Ridge, Black Sea.
Navigate to Black Sea. Use both bathimetric satellite map and a terrain map over the region. Probably I am not the first to suggest that it looks like the very Shatsky Ridge (Black Sea) was the source of the force that diverged "Georgia-Russia-Crimea" seaside from "North Anatolia" seaside. The Shatsky Ridge acted like oceanic divergent boundary and, probably, the crust it had spread was the type of "oceanic" thickness crust. The tracks of the diverging process on shore can be seen as far as up to East end of Pontic Mountains , - East end of Pontic Mountains and Greater Caucasus were diverged some tens kilometers here. Closer to Black sea the mountains diverged roughly over twice greater distance. And under water the divergent process was even stronger. The good temperature gradient through the boundary helped it, the stronger process - the greater distance of the diverging, - the Crimea is approx 400 km north from North Anatolia now.
Locating the missing diverged mountain structure.
The divergent ridges turned south at Laspi. To locate the matching mountains on Anatolia's side, why not to look for the mountains that face north with their broken planes. The corresponding region will be the region where North Anatolian Mountains turn south, that is Bartin Province, Turkey. Let's look at the relief structure aprox 40 km East-North-East from Bartin, near Dongelce, the mountain structure with perfect right angles if seen from top. If un-diverged, the coastline would rotate the mountain structure to face the structure planes north. The structure seems to be the only such "right angles" structure for all the North Anatolian Mountains, and it's placed right when the ridges turn from north-south to east-west direction. If we assume the Anatolian side uplifted a a few hundred meters to let the structure be that deep on-shore, than the heights of the mountains on both sides seem to be roughly equal and the conclusion could be that the Dongelce mountain structure seems to match Laspi's broken ridges quite well.
Tracking the two sides of the boundary from Laspi, Crimea to Georgia.
Let's select a point on a Georgian side to evaluate the distances for matching locations on the divergent sides. Let it be P'arts'khanaqanevi, Georgia. The suggested matching locations could be:
- Yalta, Crimea seems to match Aydincik-Doganyurt, Turkey.
- Feodosia, Crimea seems to match Caylioglu, Turkey. Using the map in "Terrain" mode we could see how well Feodosia's line of lower mountains would flow into the Caylioglu's lower mountains.
- Novorossiysk-Anapa, Russia extended fragment of mountains seems to fit Carsamba, Turkey.
The distances from Novorossiysk and Carsamba to P'arts'khanaqanevi seem to be roughly equal, - one could try tracking the rest of the two sides.
Suggesting the mechanism that diverged the ridge.
The conditions a divergent boundary to start developing are:
a) significant deformations within the crust;
b) access for magma from beneath of the deformed region;
c) good temperature gradient that can be achieved by presence of water layer on top of the deformed region;
Ability to develop significant deformations could be expected along the line where two plates bumped into each other previously. In our case the plates are Anatolian and Russian plates. The accreted crust on Anatolian and Russian sides got pressed against each other to create a mountain system. But the two sides of the system still were loosely coupled with each other because the accreted pieces of crust were inclined in opposite directions for the sides. The oceanic crust is denser than the plate's one, therefore the accreted piece of crust would rather subduct its end under the plate. For Anatolian plate the accreted crust would be inclined from North to South, for Russian plate the accreted crust would be inclined from South to North.
The two plates met only by tops of their accreted crust. There were no pieces of crust beneath the boundary, the pieces that could add strength to the boundary and could block magma from beneath.
On deformations magma propagated upward, and with sufficient cooling, that is, with water layer on the top, the divergent boundary developed. The northern border of the boundary was spread as The Greater Caucasus, the southern border was spread as Pontic Mountains.
Special conditions along the divergent boundary.
The mountain system turned left around the point "Laspi-Dongelce". The mechanism of accretion was special in the region. Pieces of the crust shifted significantly perpendicular to the course of the boundary. See the evidence of the divergent processes:
- on Anatolian side - "Evidences Of Old Diverging Process Within North Anatolian Mountains." ( http://sukhotinsky.blogspot.com/2011/08/evidences-of-old-diverging-process.html ).
- on Crimean side the evidence of the divergent processes could be the Baidar Valley. Navigate to Laspi, Crimea. The Baidar Valley will be North-East of it over few kilometers.
Shifted pieces of crust prevented the diverging process from developing in this corner region for the reason the shifted pieces could have blocked magma from reaching the boundary and also they could have added strength to the region against the deformations. The blocked diverging process tiered both sides together in the region, so the significant diverging force was developed to break the link between the divergent sides "Laspi-Dongelce". Probably it was this force that deformed the northern side of the boundary, the fragment rotated slightly counterclockwise, thus the Crimean southern coastline is not parallel to North Anatolian coastline now.
The coastline rotated and Crimean southwest still continue blocking the diverging process locally. As the divergent boundary - Shatsky Ridge - moved off the Crimean coast, the developing gap between the ridge and the coastline consists of thinner crust and thinner sediment layers. That's probably why this newly spread crust is the deepest place in the sea.
Active divergent boundaries and forced divergent boundaries over the Black Sea basin.
Two active divergent boundaries were formed - Shatsky Ridge, and the ridge "Istanbul, Turkey - Sevastopol, Ukraine". "Active" means that the diverging force was developed within the boundary. It seems, the "Istanbul - Sevastopol" boundary later had deactivated and was moved north-west by the forced diverging process, the process at which the force did not originate within the boundary, the force to diverge the basin was applied externally. A number of such forced divergent boundaries could be identified on the sea floor between the "Istanbul - Sevastopol" divergent boundary and North Anatolia as narrow trenches on the sea floor. The "Istanbul-Sevastopol" divergent boundary moved north-west and now looks more like "Burgas-Sevastopol" divergent boundary.
Black Sea northwestern basin development, the suggestion on.
The divergent ridge would affect the region far beyond the point the ridge turned south. In fact the deformations are not local, they are at least of Europe scale. The fact that the ridge turned south, means that no divergent boundary would go north-west, but still, the deformations caused ruptures in the north-west crust, the ruptures, possibly, were filled with sediments, the average level of sediments lowered below sea level and, thus, the north-western basin developed.
Azov Sea development, the suggestion on.
The "Istanbul-Sevastopol" divergent boundary can be tracked south-west, and, possible, could affected north-east as far as Azov Sea region. The ruptures, possibly, were filled with sediments, the average level of sediments lowered below sea level and, thus, the Azov Sea developed.
Some thought in conclusion.
The concept of active divergent boundary, that is the boundary where the diverging force is getting developed, is quite efficient concept. It could be used to explain not only intercontinental tectonic processes, but also to explain very local intra-continental tectonic processes.
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reposted from http://sukhotinsky.blogspot.com/
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16 August, 2011
14 August, 2011
Evidences Of Old Diverging Process Within North Anatolian Mountains.
Navigate to Abdipasa, Turkey. Set the map to "Terrain" mode. The small valley on the west to Abdipasa seems to be the result of a diverging process. How had the diverging process managed to took place within the mountain system, the mountain system that is thought to be under heavy compression at that time? That's one of the points of the next post on the mechanism of Black Sea opening and the Crimean Mountains origin.
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reposted from http://sukhotinsky.blogspot.com/
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reposted from http://sukhotinsky.blogspot.com/
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04 August, 2011
Ural-Putorana Diverged, Suggesting The Global Mechanism Behind The Event.
Looking at the bigger picture.
"Norilsk pizza" formation of diverged mountains is incredible (see "More On Flood Basalt, Or Siberian Traps Suggested Scenario" ( http://divergent-boundaries.blogspot.com/2011/08/more-on-flood-basalt-or-siberian-traps.html )). The crust extension mechanism scenario for Siberian Traps was suggested.
But this time let's look at the bigger picture. Take a look at the map of Siberia by "Captain Blood" "Fil:Russland topo.png" ( http://no.wikipedia.org/wiki/Fil:Russland_topo.png ) [Accessed Aug-04, 2011]. Examine the region bordered by
- Ural Mountains;
- up over Vaygach Island;
- up and right on Novaya Zemlya;
- right and down through Taymyr Peninsula;
- down Putorana Plateau all the way to Krasnoyarsk;
- from Krasnoyarsk - left through Novosibirsk - Omsk - back to South Ural Mountains;
Ural-Putorana Diverged.
Now, the question is, - Did Ural and Putorana diverged from each other and did Novaya Zemlya and Taymyr Peninsula diverged from them as well. I think, yes, they did. I've looked through approx a couple dozens of docs on the regional geology. Mostly they were from adsabs.harvard.edu (The Smithsonian/NASA Astrophysics Data System). You may search the site with relevant keywords to find the docs, look through them and make you opinion. This post is not to prove that the diverging took place, this post is to suggest a mechanism to drive the diverging process.
Divergent boundaries are behind the forces acting on a continent's borders.
Let's imagine a divergent boundary in South-North direction (at the time of Siberian Traps event) similar to the current Atlantic divergent boundary. Let the boundary point to in-between what was at the time Ural and Putorana of Siberia. Another boundary to imagine would be the one corresponding to a circle of latitude in southern hemisphere similar to current divergent boundary around Antarctic. The continent under the question is somewhere between North Pole and Equator.
The divergent boundaries are spreading out the oceanic crust. The spread crust has two options: either to get broken into pieces and then get accreted by a continent, or to subduct under the continent. In our case we have a continent driving South on the subduction zone under its south border. The force to drive the continent is developed by the south "latitude circle" divergent boundary as it acts on the continent's north border with greater force than on its south border due to the subduction process against the continent's south border.
The continent had to brake into the two subcontinents.
The point is that the south "latitude circle" divergent boundary does not press evenly on the north border of the continent, because another divergent boundary (South-North) approaches the continent from North. This "longitude" divergent boundary not only itself does not press on continent's border in that north location, it also blocks "latitude circle" divergent boundary from pressing on the continent border in the location. Besides, the "longitude" divergent boundary also adds pressure on the continent's north border on the left and on the right from the location.
Let's look at the maps. If the "longitude" divergent boundary were close to Novaya Zemlya and Taymyr Peninsula, then Novaya Zemlya and Taymyr Peninsula naturally would had been saved by the "longitude" boundary from moving south. The rest of the northern border would move south with the continent. The continent had to brake back into the two subcontinents at this point: proto-Europe and proto-Asia, so to say.
I'd like to think the subcropping basalt fields could identify the divergent regions, see the image that follows the text "Details of the Siberian Trap deposits are evident in this map" on the web page "Sction 18. Basic Science II. Impact Cratering." ( http://rst.gsfc.nasa.gov/Sect18/Sect18_4.html ) which belongs to NASA, "Remote Sensing Tutorial" by Dr. Nicholas M. Short, Sr. ( http://rst.gsfc.nasa.gov/ ) [Accessed Aug-04, 2011].
The reasons why the subcontinents had to diverge:
- Earth's spherical geometry. In high latitudes each kilometer of the propagation to South would increment the belt's length by approx 3 km. Taymyr Peninsula is about 400 km behind the location it would reach if it followed the continent. So, the resulting one thousand km, or so gap between Ural and Putorana is not unexpected.
- The "longitude" divergent boundary itself helps the sub-continents to break apart, just because of the direction of its crust spreading.
- A divergent boundary may had formed within the spreading zone like, probably, it did in the Southern Death Valley (see "Diverging The Southern Death Valley" http://divergent-boundaries.blogspot.com/2011/06/diverging-southern-death-valley.html ). The probable horst "Confidence Hills" along the center-line might mean the divergent boundary worked against the valley borders, - the temperature vertical gradient was good as the valley was underwater. But in our Ural-Putorana case I don't see horsts, rather I see grabens in North to South direction. That could mean the diverging was caused by external forces (see 2 descriptions above).
Some thoughts in conclusion.
Documents, I've got through, suggest the Siberian Traps event took about one million years. That means on average 100 sm per year of crust spreading total in East-West direction just between Ural and Putorana each year on the course of a million years.
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reposted from http://sukhotinsky.blogspot.com/
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"Norilsk pizza" formation of diverged mountains is incredible (see "More On Flood Basalt, Or Siberian Traps Suggested Scenario" ( http://divergent-boundaries.blogspot.com/2011/08/more-on-flood-basalt-or-siberian-traps.html )). The crust extension mechanism scenario for Siberian Traps was suggested.
But this time let's look at the bigger picture. Take a look at the map of Siberia by "Captain Blood" "Fil:Russland topo.png" ( http://no.wikipedia.org/wiki/Fil:Russland_topo.png ) [Accessed Aug-04, 2011]. Examine the region bordered by
- Ural Mountains;
- up over Vaygach Island;
- up and right on Novaya Zemlya;
- right and down through Taymyr Peninsula;
- down Putorana Plateau all the way to Krasnoyarsk;
- from Krasnoyarsk - left through Novosibirsk - Omsk - back to South Ural Mountains;
Ural-Putorana Diverged.
Now, the question is, - Did Ural and Putorana diverged from each other and did Novaya Zemlya and Taymyr Peninsula diverged from them as well. I think, yes, they did. I've looked through approx a couple dozens of docs on the regional geology. Mostly they were from adsabs.harvard.edu (The Smithsonian/NASA Astrophysics Data System). You may search the site with relevant keywords to find the docs, look through them and make you opinion. This post is not to prove that the diverging took place, this post is to suggest a mechanism to drive the diverging process.
Divergent boundaries are behind the forces acting on a continent's borders.
Let's imagine a divergent boundary in South-North direction (at the time of Siberian Traps event) similar to the current Atlantic divergent boundary. Let the boundary point to in-between what was at the time Ural and Putorana of Siberia. Another boundary to imagine would be the one corresponding to a circle of latitude in southern hemisphere similar to current divergent boundary around Antarctic. The continent under the question is somewhere between North Pole and Equator.
The divergent boundaries are spreading out the oceanic crust. The spread crust has two options: either to get broken into pieces and then get accreted by a continent, or to subduct under the continent. In our case we have a continent driving South on the subduction zone under its south border. The force to drive the continent is developed by the south "latitude circle" divergent boundary as it acts on the continent's north border with greater force than on its south border due to the subduction process against the continent's south border.
The continent had to brake into the two subcontinents.
The point is that the south "latitude circle" divergent boundary does not press evenly on the north border of the continent, because another divergent boundary (South-North) approaches the continent from North. This "longitude" divergent boundary not only itself does not press on continent's border in that north location, it also blocks "latitude circle" divergent boundary from pressing on the continent border in the location. Besides, the "longitude" divergent boundary also adds pressure on the continent's north border on the left and on the right from the location.
Let's look at the maps. If the "longitude" divergent boundary were close to Novaya Zemlya and Taymyr Peninsula, then Novaya Zemlya and Taymyr Peninsula naturally would had been saved by the "longitude" boundary from moving south. The rest of the northern border would move south with the continent. The continent had to brake back into the two subcontinents at this point: proto-Europe and proto-Asia, so to say.
I'd like to think the subcropping basalt fields could identify the divergent regions, see the image that follows the text "Details of the Siberian Trap deposits are evident in this map" on the web page "Sction 18. Basic Science II. Impact Cratering." ( http://rst.gsfc.nasa.gov/Sect18/Sect18_4.html ) which belongs to NASA, "Remote Sensing Tutorial" by Dr. Nicholas M. Short, Sr. ( http://rst.gsfc.nasa.gov/ ) [Accessed Aug-04, 2011].
The reasons why the subcontinents had to diverge:
- Earth's spherical geometry. In high latitudes each kilometer of the propagation to South would increment the belt's length by approx 3 km. Taymyr Peninsula is about 400 km behind the location it would reach if it followed the continent. So, the resulting one thousand km, or so gap between Ural and Putorana is not unexpected.
- The "longitude" divergent boundary itself helps the sub-continents to break apart, just because of the direction of its crust spreading.
- A divergent boundary may had formed within the spreading zone like, probably, it did in the Southern Death Valley (see "Diverging The Southern Death Valley" http://divergent-boundaries.blogspot.com/2011/06/diverging-southern-death-valley.html ). The probable horst "Confidence Hills" along the center-line might mean the divergent boundary worked against the valley borders, - the temperature vertical gradient was good as the valley was underwater. But in our Ural-Putorana case I don't see horsts, rather I see grabens in North to South direction. That could mean the diverging was caused by external forces (see 2 descriptions above).
Some thoughts in conclusion.
Documents, I've got through, suggest the Siberian Traps event took about one million years. That means on average 100 sm per year of crust spreading total in East-West direction just between Ural and Putorana each year on the course of a million years.
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reposted from http://sukhotinsky.blogspot.com/
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01 August, 2011
More On Flood Basalt, Or Siberian Traps Suggested Scenario.
Some Siberian Traps observation.
Navigate to Noril'sk using a map tool, set it to "Terrain"mode". See "Imangda Rudnaya" approx 70 km East-South-East from Noril'sk. Then, see six-point divergent star relief structure aprox 30 km East-North-East from "Imangda Rudnaya". The "pizza" of mountain ridges were cut into six pieces, and the pieces were diverged off the center approx 5 km, the space between pieces was filled with basalt. How could that happen?
Suggested scenario.
- The strong diverging process caused by Moon induced deformations (Moon was closer to Earth at the time) was mostly located on North and the continent was accreting incoming crust from North.
-The belt on Earth surface (corresponding to a circle of latitude(or parallel)) consisting of a) cratons, b) accreted chunks of oceanic crust, c) just oceanic crust was moving south under the force from North.
- In higher latitudes each kilometer of the belt's propagation to South would increment the belt's length by approx 3 km.
- 10 sm/year of the propagation in the course of a million years would increase the belt's length up to 300 km.
- Cratons and newly spread oceanic crust are not easy to get broken to compensate the expanded belt. The assembly of loosely coupled chunks of accreted crust would disassemble to accommodate the increased surface even without the help of extension force. The loosely coupled chunks would spread just because of the deformations caused by Moon and/or by the deformations caused by the incoming subducting crust.
Pangaea-related consideration.
If the scenario is valid and the movement of East Pangaea was persistent on the course of at least 100 My, then, would not it mean that the entire Pangaea was located around South Pole before braking-up?
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reposted from http://sukhotinsky.blogspot.com/
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Navigate to Noril'sk using a map tool, set it to "Terrain"mode". See "Imangda Rudnaya" approx 70 km East-South-East from Noril'sk. Then, see six-point divergent star relief structure aprox 30 km East-North-East from "Imangda Rudnaya". The "pizza" of mountain ridges were cut into six pieces, and the pieces were diverged off the center approx 5 km, the space between pieces was filled with basalt. How could that happen?
Suggested scenario.
- The strong diverging process caused by Moon induced deformations (Moon was closer to Earth at the time) was mostly located on North and the continent was accreting incoming crust from North.
-The belt on Earth surface (corresponding to a circle of latitude(or parallel)) consisting of a) cratons, b) accreted chunks of oceanic crust, c) just oceanic crust was moving south under the force from North.
- In higher latitudes each kilometer of the belt's propagation to South would increment the belt's length by approx 3 km.
- 10 sm/year of the propagation in the course of a million years would increase the belt's length up to 300 km.
- Cratons and newly spread oceanic crust are not easy to get broken to compensate the expanded belt. The assembly of loosely coupled chunks of accreted crust would disassemble to accommodate the increased surface even without the help of extension force. The loosely coupled chunks would spread just because of the deformations caused by Moon and/or by the deformations caused by the incoming subducting crust.
Pangaea-related consideration.
If the scenario is valid and the movement of East Pangaea was persistent on the course of at least 100 My, then, would not it mean that the entire Pangaea was located around South Pole before braking-up?
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reposted from http://sukhotinsky.blogspot.com/
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25 July, 2011
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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reposted from http://sukhotinsky.blogspot.com/
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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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reposted from http://sukhotinsky.blogspot.com/
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22 July, 2011
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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reposted from http://sukhotinsky.blogspot.com/
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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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reposted from http://sukhotinsky.blogspot.com/
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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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reposted from http://sukhotinsky.blogspot.com/
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- 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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reposted from http://sukhotinsky.blogspot.com/
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12 July, 2011
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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reposted from http://sukhotinsky.blogspot.com/
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edited Aug-17, 2011.
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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reposted from http://sukhotinsky.blogspot.com/
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edited Aug-17, 2011.
07 July, 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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reposted from http://sukhotinsky.blogspot.com/
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edited: Aug-17, 2011
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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reposted from http://sukhotinsky.blogspot.com/
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edited: Aug-17, 2011
01 July, 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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reposted from http://sukhotinsky.blogspot.com/
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reposted from http://sukhotinsky.blogspot.com/
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27 June, 2011
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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reposted from http://sukhotinsky.blogspot.com/
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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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reposted from http://sukhotinsky.blogspot.com/
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18 June, 2011
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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reposted from http://sukhotinsky.blogspot.com/
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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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reposted from http://sukhotinsky.blogspot.com/
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03 June, 2011
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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reposted from http://sukhotinsky.blogspot.com/
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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.
--
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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reposted from http://sukhotinsky.blogspot.com/
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27 May, 2011
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 ).
---
reposted from http://sukhotinsky.blogspot.com/
---
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 ).
---
reposted from http://sukhotinsky.blogspot.com/
---
22 May, 2011
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.
---
reposted from http://sukhotinsky.blogspot.com/
---
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.
---
reposted from http://sukhotinsky.blogspot.com/
---
18 May, 2011
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.
---
reposted from http://sukhotinsky.blogspot.com/
---
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.
---
reposted from http://sukhotinsky.blogspot.com/
---
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