My science/technology-related thoughts, sometimes controversial, sometimes can be based on limited knowledge base, logic can be non-perfect as well. I develop my vision in iterations. Don't take this blog as an attempt to convince anybody in anything. Each post in this blog reflects my level of understanding of Tectonics of the Earth at the time the post was written; so, some posts may not necessarily be correct now.
From my previous post "The Formation Of A Satellite Of A Celestial Object By The Differentiation Of Particles' Speed Vectors." < http://divergent-boundaries.blogspot.com/2011/10/formation-of-satellite-of-celestial.html > it seems that it's impossible to deny that when the material was gathered to create Earth, some part of it did not go to the center, instead it kept on orbiting around it to start creating Moon. The question is, what percentage of the Moon's body was added by the mechanism? Did not exist another mechanism to add the material to the Moon?
The mentioned mechanism can be attributed to the Condensation Theory, as the ring of the outer stuff and the stuff inside the ring started to condense almost at one time. But the question remains, can't the process of condensing of inner stuff cast off more rings? (In the mentioned above my previous post "The Formation Of A Satellite Of A Celestial..." I wrongly used "disk" word instead of "ring", my language problem, sorry.)
It seems the gravity force can make the inner stuff to cast off another one or more rings. What would be the effect of the differentiation of the inner stuff by its density? Maybe I, Sergey D. Sukhotinsky, the author of this post am missing something, but the effect of the differentiation would be increased speed of rotation to keep angular momentum. If the viscosity of the stuff is significant, the outer layer would be rotating fast enough to get ejected on Equator. New ring would be formed.
The rings are not parts of the Geodynamo. But, probably, are affected by the Geodynamo's magnetic field that gets reversed from time to time. That's why, probably, their orbits were inclined relative to Equator plane. Accordingly, the Earth's Equator plane got inclined relative to the plane of Solar system. Over time the rings condensed into two or more moons. The "moons" collided eventually due to the gravitational interaction with the Earth and each other.
The idea described above in this post and in my previous post "The Formation Of A Satellite Of A Celestial Object By The Differentiation Of Particles' Speed Vectors." < http://divergent-boundaries.blogspot.com/2011/10/formation-of-satellite-of-celestial.html > looks like to be valid on a bigger scale: not only for the formation of satellites of planets, but also for satellites of stars, - why not to think that the material for an innermost planet was ejected by the process described in this post?
In my previous post "Hawaii Convergent, Part 2. Introducing The Concept Of Geofracture (not Plate) Tectonics." < http://divergent-boundaries.blogspot.com/2011/10/hawaii-convergent-part-2-introducing.html > I proposed the concept of the interdisciplinary study on formation and evolution of the Earth's upper solid layer. As the main driving force of the formation and evolution is suggested to be by Moon/Sun, I need a concept when and how Moon was formed. Upon searching for the concept, I could not find any that would fit my vision; probably I should had searched more; or just let's try to develop the concept: -- - The stuff around the (now) Earth's orbit gets gathered into the gaseous pre-Earth.
- The particles are colliding, thus loosing their speed through radiation.
- The particles that happened to stay high on the circular orbits, are getting less and less likely to be disturbed by a collision because particles with "wrong" orbits are getting trapped by the mess in the center; the trapped by the mess are losing their speed and getting down onto the lower orbits.
- Fallen down particles eventually form liquid Earth; but the "coherent" (so to say) by the vector of speed, particles form disk around Earth above Equator.
- The disk is not a part of the Geodynamo anymore, but, still, probably is getting affected by the Geodynamo's magnetic field that gets reversed from time to time. That's why, probably, the Moon's orbit got inclined relative to Equator plane.
- The particles within the disk are getting condensed due to the gravitational interaction, the chunks are gathered into the Moon eventually, so the pattern we see on the Moon's surface may not necessarily all be due to collisions with asteroids, some "big picture" formations probably could be the result of the process of the chunks gathering. -- The described above process of the formation of the Moon by the differentiation Of particles' speed vectors could probably work for other celestial objects; Saturn probably still is in the process with it's disks. On a bigger scale the concept could probably be applied to the relation between Sun and the planets, or even between stars in a star system. Sergey D. Sukhotinsky. http://divergent-boundaries.blogspot.com/ http://sukhotinsky.blogspot.com/ http://weblogs.asp.net/SergeyS/default.aspx ---
Revisiting part one. In my previous post: "Hawaii Hotspot Puzzle. Suggesting Hawaii As A Moving Convergent 'Coldspot'". < http://divergent-boundaries.blogspot.com/2011/09/hawaii-hotspot-puzzle-suggesting-hawaii.html > I tried to explain Hawaii seamount chain using the idea developed in my previous posts (and expressed in my message #6247 (24 Aug 2011 12:35) "A message on Active Boundary Plate Tectonics" to <GEO-TECTONICS@JISCMAIL.AC.UK> ) that: a) the process of pumping magma/lava up requires: - thermal gradient; - deformations to cause sufficient local displacements of magma/lava; b) - if cooling of the upper layers of the boundary is "good enough" the boundary overcomes the compression in crust; a divergent process develops under Moon/Sun induced deformations; - if cooling of the upper layers of the boundary is not "good enough" the boundary can't overcome the compression in crust; a convergent process develops under Moon/Sun induced deformations;
The post was focused on explaining Hawaii's "as a convergent 'Coldspot'": - The geometry of global tectonic forces maintains focused deformations. Convergent process along a segment of line is developed under the external compression. - The process of pumping magma/lava up surface stops when the segment gets out of focus of the deformations and the convergent location gets too thick and "diffused" in terms of thermal gradient. (Actually the phrase was without "on surface", it was just "the process of pumping magma/lava up", - my mistake).
The tail of the convergent "coldspot" does not break on fracture zones. In the post I tried to explain "Hawaii/Murray Fracture Zones" puzzle, - the microplates on both sides of Murray Fracture Zones were spread at different rates. After the Hawaii "head" passed Murray Fracture Zone, the path-line should be broken at the fracture zone, but it does not. The same holds for other fracture zones. The explanation (revisited) could be as follows:
How do different spreading rates of microplates get accommodated: When the process of pumping magma/lava to surface stops, does it mean that the deformations-induced convection stops beneath the ocean floor? I think, no, it does not due to the presence of thermal gradient and local displacements. Still, the sediments contaminated stuff circulates beneath a non-active volcano. The stuff just does not reach the surface. Now the wide region beneath the volcano gets spoiled with sediments, melting temperature drops, the effective thickness of crust drops as well. The volcano keeps on subsiding. The microplates different spreading rates get accommodated by, so to say, different rates of sea mount subsiding.
Even if a microplate spread faster, it can't shift a volcano segment far from the centerline. The most deformations are focused on the centerline; if a volcano segment is moved by the microplate off the centerline, the side of a volcano that is closer to the centerline is getting more amplitude of deformations, and the crust of the side is consumed more intensely, that's the kind of negative feedback to keep the volcano segments close and parallel to the centerline, but not too close to the centerline if the center is already occupied by other volcano segment because the crust there is contaminated with sediments. In that case of partially overlapped segments, I'd expect the head of a forward segment to be on the centerline, but it's rear to be off the center as the center is already occupied. The "ductile" island chain as a part of a bigger picture. At some point the balance is reached, and the volcano subsidence stops. The balance is between volcano weight, crust effective thickness, compression stress in crust. (Roughly, the rate of change of effective thickness of crust depends on heat supply by the deformation induced convection, heat taken off through the surface and other factors). Such "ductile", so to say, island could probably be used to measure time variations of stress in oceanic crust. Perhaps a laser-based tools could do the job by measuring the island 3-D dimensions.
Geofracture (not Plate) Tectonics, talking on the concept of the interdisciplinary study. Number of branches of science can study Earths brittle/dactile layers, to name a few: Fracture mechanics, Continuum mechanics, Rheology. For example:
- The pattern of global fracture zones (boundaries) in Earth's brittle layer developed due to Moon/Sun induced deformations could be handled by Fracture mechanics. Good example, I think, can be suggested mechanism behind The Siberian Traps. See my blog post "Ural-Putorana Diverged, Suggesting The Global Mechanism Behind The Event." < http://divergent-boundaries.blogspot.com/2011/08/ural-putorana-diverged-suggesting.html > The extension process of the region was suggested to happen due to forced move from higher latitudes to lower latitudes. Between the fixed boundaries such move from higher latitudes to lower means extension over the region.
- The property of a boundary to develop divergent or convergent process could be handled by Rheology, for instance the convergent property of Hawaii volcanoes chain (this and previous posts). The pattern of oceanic intra-plate convergent zones, still, can be handled by Fracture mechanics, but diverging/converging characteristics of the zones seem to be addressed by Rheology.
- Continuum mechanics could study a plate as a complex system of "brittle/ductile" components. For example, the intra-plate Yellowstone Caldera could be seen as a system of volume of magma locked by plates from bottom, top and other sides. The dynamics of stress pattern around it reflects the caldera behavior.
Refining Geofracture Tectonics. The ultimate goal of my posts on Tectonics is not just to reveal the mechanics behind the Tectonic events, but rather to suggest the ideology of modelling the mechanics. The modelling requires special hardware setup, special software over it, but that's the theme for a separate set of posts. I don't see how some classic Plate Tectonics terms could be maintained by Geofracture Tectonics, to name a few:
- The timescale with the fancy words like Cenozoic, Mesozoic etc; Rules of Mechanics should not depend of dinosaurs population, instead dinosaurs should depend on mechanics. There is the only time unit - second, To make records shorter, Tera second (Tc) can be used. - The words asthenosphere, lithosphere seem to be somewhat outdated (my post "Plate Tectonics. Thinking Out Of The Sphere"). Plates are very diverse, plates are completely decoupled from each other by boundaries. Plates can reach depth of many hundreds km, or their thickness can be only few km. I don't see any need to organize the internals of the plates into any artificial the Earth-global entities (spheres) like asthenosphere or lithosphere. The changes of properties of plates with depth that are seen with Geophysics instruments could mark the layers' boundaries. The layers defined this way could be called in plain English, such as "brittle", "ductile", "transition" or similar. ---
I'm sure I am not the first to point out the next fundamental controversy about Hawaii Hotspot. Let's consider the border between the two microplates: - first: the microplate between Mendocino and Murray Fracture Zones. Let's assume Kure Atoll, Midway Atoll belong to this microplate. - second: the microplate between Murray and Molokai Fracture Zones. Let's assume Pearl and Hermes Atoll, Laysan Island belong to this microplate.
Rolling events back. Murray Fracture Zone points roughly to Pearl and Hermes Atoll that is approx 2,300 from Kilauea, current location of the hotspot. Rolling events back, we may suggest that at proposed 8-9 sm/year speed, the hotspot was at Pearl and Hermes Atoll location some 25-30 million years ago.
To see how the microplates were positioned one relative to another back 25 MY ago, let's just cut the oceanic crust that was spread for the past 25 MY (including the crust that has been overridden by the NA continent). There is huge difference between the amount of crust that was spread by the microplates. Roughly, the second plate added approx more than 400km of it's length than the first microplate did.
Hotspot motion. Back 25 MY: - the oceanic floor of Pearl and Hermes Atoll was approx 400km east relative to Midway Atoll . - then in no time the hot spot must had jumped from Midway Atoll over that 400km east to build Pearl and Hermes Atoll. - then the hotspot slowly returns to its normal position; the Pearl and Hermes Atoll, that was left behind the hotspot, returns back on the faster moving microplate to get in line with Kure and Midway Atolls. This concept of "smart" oscillating hotspot looks unrealistic to me.
Some break in the path around Pearl and Hermes Atoll seems to exist, but as the break distance is considerably less than expected 400km, we may conclude that the microplates did spread at different rates, but the spot is the feature of geometry of global tectonic forces around the region.
Suggesting another mechanism for Hawaii - moving convergent "coldspot". The microplates are spreading out at different rates and are bumping into the wall of oldest crust. There must be convergent/divergent zones to accommodate the different rates of the crust spreading. Why not to suggest Hawaii to be a part in the convergent process?
Comparing magma beneath the divergent boundary to the stuff beneath a convergent "coldspot". The material of the accommodated crust is not exactly the same as the material of the fresh magma coming from bottom into the divergent boundary. Accommodated sediments change chemical composition and melting point of the stuff beneath the convergent "spot". In fact as the melting point gets lower, the spot along the path better be called "coldspot", not "hotspot". Many other parameters should be different between the fresh magma and the stuff beneath the spot, but, I, Sergey D. Sukhotinsky, the author of this post, think that this probably should be the theme for another post.
Conditions to maintain the process of pumping magma/lava up. - sufficient temperature gradient along the magma/lava path; - deformations within the spot of the amplitude and speed to cause sufficient local displacements of magma/lava;
Conditions the process of pumping magma/lava stops at:- too much oceanic crust is brought up and down by the convergent coldspot: a)the cold layer gets too thick, the temperature gradients gets too low; b)the spot "diffuses"; the greater region gets the deformations, local displacements of magma/lava diminishes; - the spot moves off the focus of global tectonic forces, the amplitude of crust deformations drops. The regions cools down as magma stops pumping up; the region gets resistant to deformations due to the increased thickness of crust.
The focus of global tectonic forces probably is the intersection of the two lines: - North to South fracture line through the Pacific plate. - West to East probable fracture line connecting south borders of Asia and North America. Thick and rigid continents prevent Pacific plate from bending between continents along West-East line when Moon's plane of orbit gets North. Thus the max bending stress of Pacific plate would be along the probable WE fracture line connecting south borders of Asia and North America.
The "coldspot" process resumes: - the focus of global tectonic forces moves south-east on the plate as the plate itself moves north-west; - magma under the new location is not spoiled with sediments; - the amplitude of crust deformations is good at the location because the crust here is pre-bent by the load of the chain of volcanoes and the chain itself ceased to bend due to the increased thickness. New fracture segment develops south-east to the old sub-chain of volcanoes. The fracture pumps magma up developing new segment of the volcano chain.
How to tell if the concept is correct. I need more time to figure it out; right now I got a couple of ideas on where to look for the evidences: - the relief of the chain of volcanoes should show that the region is under west-east compression, that contradicts slab-pull concept but is in line with ridge-push concept; - there should be a gap in the age of the sediments (and crust) on the both west and east sides of the chain because some crust was consumed to build the volcanoes and to recycle the bottom of the spot into underlying magma. The time-width of the time-gap should roughly be equal to the time span a volcano was active within. That is somewhat greater time than it is now usually thought of. That's because the evidence of early activity of a segment of volcano chain is hidden deep within the volcano or even got molten and got recycled into the underlying magma. I'd like to estimate the time gap could be as great as up to 10MY. --
Code First, Model First, or Behavior First? (Talking On Plate Tectonics, Earth Science).
Software industry to address Plate Tectonic. With the "Model First" concept a developer still needs to suggest a model. What if a model were to be built automatically, based on a set of observations? That's probably too fantastic in a general case. But, does a special case exist to justify it? I think, yes, this can be Plate Tectonics, Earth Science.
The very nature of Earth Science is that it's impossible to reach the depths of the Earth to see directly what's going on there. So different models exist to explain the tectonic processes. The most widely accepted one is Plate Tectonics. Phrases like "is thought to be", "is widely accepted", "is postulated", etc are not uncommon within the model. The mainstream of the model does not take Earth as a rotating body at all and one could find other issues with the model on the closer look at it.
Software "Model First" evangelists are scientists, for sure. They are the most advanced specialists to handle future "Behavior First" concept. So, the question is, why have Software and related industries wait for "Earth Science" scientists to figure out which model fits better the geology/geophysics observations? Why not to help them to convert the stream of ongoing observations into the process of building the relevant model? The best professionals to handle the task belong to software industry.
Let's name some reasons why Software and related industries may consider participating in building the relevant Tectonic model of the Earth:
a) Software industry:
1. The industry possesses the best professionals to handle the task. The task spans both "Model First" and "Behavior First" domains. It would be only natural for the industry to jump on the train, running one of the AI rails.
2. Good knowledge of possible future seismic events is vital to the industry.
b) Electronic Components and Electronic Devices industries:
1. Steady supply of materials is vital for the industry. Plate Tectonics is not only about how do continents move. Plate Tectonics is also about how do the deposits of elements form and where to dig them. (See "Porphyry Copper. More On Reshaping Pangaea (Gondwana)" ( http://divergent-boundaries.blogspot.com/2011/07/porphyry-copper-more-on-reshaping.html ), some ideas were left behind the post.)
2. The same as the point 2 for Software industry.
3. The industries could provide the hardware that is optimized to address the task.
c) Other industries, to name a few: auto-, mil- related, etc.
1. A set of reasons including some of those mentioned above.
Suggesting Active Boundary Plate Tectonics model.
Probably I would not post it if I, Sergey D. Sukhotinsky, the author of this message had not developed the draft of new concept of Plate Tectonics. The concept, in my opinion, is quite promising as I found it to explain the tectonics-related observations quite nicely. The story started on 26-Apr,2011 when I posted a request to "Tectonics & structural geology discussion list" <GEO-TECTONICS@JISCMAIL.AC.UK> to review new concept of forces behind continental drift, post #5932 on 26-Apr,2011 and post #5955 on 3-May, 2011.
The concept "Active Boundary Plate Tectonics" is based on a few suggestions. Below are some adapted excepts from my post Item #6247 24-Aug 2011 12:35 - A message on Active Boundary Plate Tectonics.<GEO-TECTONICS@JISCMAIL.AC.UK>, the post in full is at the end of this message:)
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- the suggestion that under the deformations the transition layer between crust and magma propagates in the direction of lower temperature;
- the suggestion that if the transition layer reached surface, it would build either:
a) divergent boundary if enough cooling of the surface were present (water layer over oceanic floor, say East Pacific Rise);
b) convergent boundary if the transition layer reached atmosphere (not enough cooling), I'd say - Hawaii. The upper layers of magma is getting spoiled by sediments and nearby chain of underwater volcanoes can't build the strong (divergent) boundary. (We assume the region to be under compression, not extension.)
- some other suggestions to be discussed later;
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Dear GEO-TECTONICS list members,
On 26-Apr,2011 I posted a request to review new concept of forces behind continental drift, post #5932 on 26-Apr,2011 and post #5955 on 3-May, 2011. I would agree it would be better to prepare a work, publish it, and then to discuss it on the forum, For some reason I got no option to go the standard way. Let me to sum up what I've done since then in a short message. I am not sure I'll have an opportunity to continue the work (though I'll be trying to continue it).
The initial concept did not transform too much. As for now, the concept "Active Boundary Plate Tectonics" is based on the next suggestions.
- the suggestion that under the deformations the transition layer between crust and magma propagates in the direction of lower temperature;
- the suggestion that if the transition layer reached surface, it would build either:
a) divergent boundary if enough cooling of the surface were present (water layer over oceanic floor, say East Pacific Rise);
b) convergent boundary if the transition layer reached atmosphere (not enough cooling), I'd say - Hawaii. The upper layers of magma is getting spoiled by sediments and nearby chain of underwater volcanoes can't build the strong (divergent) boundary.
- third suggestion to be discussed later;
The derived ideas range from very local geographically to planet-wide:
- Big picture on continental formation end evolution, (my blog post "Continental Formation And Evolution Revisited".)
- Pangaea layout. There was a post on this list #6165 (13-Jul, 2011) "Request for links to resources on alternative Pangaea layouts." The proposed layout was to place Australia, India, and NZ on the West of South America. Australia to be connected to "Atacama desert" region, India's cratons to be places on the North-West of Australia. NZ to be connected to South America below Australia. One of the evidences was the location of porphyry copper deposits, (my blog post "Porphyry Copper. More On Reshaping Pangaea (Gondwana)".)
- Mountain formation. (my blog post "Formation Of Mountain Ridges by Broken Process Of Subduction"). Tibet/Himalaya formation mechanism was suggested - by the consecutive "broken processes of subduction".
- Intra-continental tectonic processes. Some evidences of divergent processes within continents were pointed out: - my posts "The Snake River Plain As A Divergent Boundary", "Diverging Processes Within Las Vegas Valley", "Diverging The Southern Death Valley", "Evidences Of Diverging Processes Within Tibet Mountain System.", "Ural-Putorana Diverged, Suggesting The Global Mechanism", "Evidences Of Old Diverging Process Within North Anatolian Mountains.".
It was suggested that the diverging processes were behind the "Flood Basalt" events. The Snake River Plain divergent process was suggested to correlate to flood basalts on the North and on the South of the plain. The event of diverging Ural from Putorana was suggested to be one of the primary cause of Siberian Traps flood basalts (my blog post "Ural-Putorana Diverged, Suggesting The Global Mechanism").
A few words in conclusion. The proposed concept of Active Boundary Plate Tectonics seems to be quite efficient concept. It could be used to explain not only intercontinental tectonic processes, but also to explain very local intra-continental tectonic processes.
Thank you.
Sergey D. Sukhotinsky.
--
PS.
The most exciting for me was my work on my post "Black Sea. Some Thoughts On Its Opening And On The Origin OF The Crimean Mountains." The post was about that the divergent boundary - the Shatsky Ridge separated the Crimean Mountains off Pontic Mountains. Some evidences were discussed:
- Matching mountains on Anatolia (Dongelce) and Crimea (Laspi) side. The rectangular mountain structures can be found only in this "bent" part of Pontic Mountains.
- Matching mountains all over the divergent mountain system (Yalta, Crimea to match Aydincik-Doganyurt, Turkey; Feodosia, Crimea to match Caylioglu, Turkey; Novorossiysk-Anapa, Russia fit Carsamba, Turkey).
The mechanism that diverged the mountain system was discussed. The origin of deep see locations around Laspi was suggested.
I posted about two dozens of posts on Plate Tectonics on my blog http://divergent-boundaries.blogspot.com. Now I've made most of the posts private, but still on-demand are available the timestamped editions of them and their drafts that are stored in the cloud.
(I think, some day the blog platform host will introduce the feature to make public the saved editions of a blog post.)
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.
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. --- reposted to http://divergent-boundaries.blogspot.com/ ---
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. --- reposted to http://divergent-boundaries.blogspot.com/ ---
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? ---
reposted to http://divergent-boundaries.blogspot.com/ ---
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. --- reposted to http://divergent-boundaries.blogspot.com/ ---
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. ---
reposted to http://divergent-boundaries.blogspot.com/ ---
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 ofsteady 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. ---
reposted to http://divergent-boundaries.blogspot.com/ ---
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. --
reposted to http://divergent-boundaries.blogspot.com/ --- edited Aug-17, 2011.
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. ---
reposted to http://divergent-boundaries.blogspot.com/ --- edited: Aug-17, 2011
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.
---
reposted to http://divergent-boundaries.blogspot.com/ ---
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