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Tectonics driven by ice mass changes?

  1. May 17, 2009 #1
    Increasing glacification creates crustal tension pulling apart the mid ocean trench zones?
    Decreasing glaciation sucks out the stuffing and wreaks havok with compressive stresses, violent crustal crumpling and dropping of vunerable thin seafloor and mobile landmass plates?

    Seems a plausible hypothesis. Bundles of supporting geology, history seems to support it.

    Scary thing to think about but maybe the most important thing to consider that anyone alive now will ever have a chance to.
     
  2. jcsd
  3. May 17, 2009 #2

    matthyaouw

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    The effects of ice sheets on the height of continental landmasses is well recognised (isostacy) but this is a new idea to me. You say there is supporting geology and history- care to present it?

    Also, when you say pulling apart mid ocean trench zones, would that be ocean trenches or mid-ocean ridges you mean?
     
  4. May 18, 2009 #3
    Sounds implausible to me. Care to explain how the Himalayas formed by glaciation?

    I think you'll find that mantle convection is a far more plausible hypothesis in driving tectonics. Incidentally, I'm not saying that glaciation cannot have a topographic influence on the continents, and therefore it may be coupled to tectonics in subtle ways as in it would certainly influence local stress patterns. However I think it would be mistaken to suggest that this drives tectonics, perhaps it is more the other way around, i.e. tectonics drives glaciation? (Although we know that other factors are certainly involved in driving glaciation that are (almost?) completely decoupled from tectonics e.g. Milankovitch cycles)

    Incidentally, if you wished to pursue your theory your best bet would be to study sedimentary basins.
     
  5. May 19, 2009 #4
    I've read that theres no more heat flux in the mid ocean trenches as in "subduction" trench areas and other faultlines at present. That midocean ridges are compression features from isostatically driven volume adjustments buckling them recently, not spreading forces from vulcanism in the trenches. That Magma samples show high mobilily along trenches in fast spreading zones. That vulcanism in the midocean trenches is far less than plate techtonics predicted and not anywhere near enough to be driving seafloor conveyor belts at present. Maybe its only active and spreading during increasing glaciation periods.

    A paper on the upheaval in tectonic theories:
    http://ourworld.compuserve.com/homepages/dp5/tecto.htm [Broken]
    PDF there of it for download:
    http://www.scientificexploration.org/journal/jse_14_3_pratt.pdf [Broken]

    “Surge Tectonics” seems to have a picture of things working in expansion contraction cycles like this. But they are saying that expansion and contraction cycles are some mysterious heating and cooling in the Earth’s core.

    Theres lots of papers saying :
    -That “the earth has a tectonic heartbeat.”
    - That glacial/interglacial cycles are linked to tectonic cycles and it must be plate tectonic cycles that drive the glacial ones.
    -And papers that say that theres unexplained variability in the earth’s rotation axis, of the same period as glacial and tectonic cycles, so there must be some mystery orbital dynamic or body in the solarsystem that drives them both.
    -And papers that say that models now show earth’s axis will move when ice caps collapse.
    -Its always been no argument that continents go up and down like pistons when ice is lost and builds up again. The middle of Greenland and most of Antarctica are pushed down well below sealevel by the current middling ice loads.
    Anyone seeing a pattern in that grouping? Unfortunately I can’t see anyone saying it on the web. Maybe its career suicide to say such things in the academic churches.

    Seems to be millions of holes visible in the seabed. Those just the ones not filled by sediments. Probably post ice age hydrothermal vents if they are not filled.

    Fountains of the deep? Earth’s Saline injection holes when her heart pump Antarctica loses a lot of ice (at ~160cubickm per year 5 years ago)? Then rises, and sucks too much magma from the “Cardiovascular System” of multi kilometer wide magma pipes under plate boundaries, faultlines and ocean volcanic chains. And spleen like reservoirs up to the area of Australia. All full of runny water filled magma in a web underneath the earth’s crust?

    What if bulges like the sth pacific superswell get sucked out. Resist collapsing for a while. As water seeps in and mixes as supercritical fluid with whats left, until they buckle and fracture in the patterns you can see in ocean basin links below with crisscrossing lines of 1000km fractures, with vent craters spaced every km or so along them?

    Eg/ Google satellite links. (have some fun zooming and panning around):

    track marks from Earth shooting up off coast west of Titicaca
    http://maps.google.co.nz/maps?hl=en&ie=UTF8&ll=-19.197053,-76.135254&spn=5.227615,11.25&t=h&z=7

    track marks from Earth shooting up off coast sthwest of Stewart island NZ
    http://maps.google.co.nz/maps?hl=en&ie=UTF8&ll=-49.410973,161.762695&spn=3.602817,11.25&t=h&z=7

    Boxing Day 2004 epicentre. A ~30 cubic km of volume drop in ~500km by ~2km strip that dropped up to 30m.
    Remember reports from boats in the area that the water frothed and turned muddy black? How about the mud volcano pouring out cubic km’s of hot runny mud on the land nearby?
    Same sort of track marks but smaller holes than examples above:
    http://maps.google.co.nz/maps?hl=en&ie=UTF8&ll=4.67498,95.31189&spn=2.759079,5.625&t=h&z=8

    off sthrn Chile. big hole 15km:
    http://maps.google.co.nz/maps?hl=en&ie=UTF8&ll=-36.094609,-73.071442&spn=0.559278,1.40625&t=h&z=10

    nice big vents off Florida:
    http://maps.google.co.nz/maps?hl=en&ie=UTF8&ll=29.878755,-77.01416&spn=2.400445,5.625&t=h&z=8

    We do have a serious nutrient problem in the open oceans. Depletion of trace iron etc has half the world’s ocean area less bio-productive per area than the worst of land deserts. Maybe Earth likes to have a real good global crustal shakedown and squirt loads of 2000degrC mud out all her pores now and then to feed the phytoplankton real good.

    The last time Antarctica lost all its ice was suddenly 27 million years ago with a 6degreeC Warming event like we are expecting this century.
    New Zealand went from 10x its current size to 1/5 its current size then very suddenly. It’s called the Eocene Drowning event. Local mass species extinction. But we are told that the mantle is such a viscous immobile uniform blob that we should rise along with Antarctica as ice comes off. I'm not so confident with what I've been reading recently. Conventional Plate Tectonics is suddenly looking full of over simplified assumptions and sparse ocean floor sample data cherry picked to fit the model.
     
    Last edited by a moderator: May 4, 2017
  6. May 19, 2009 #5
    Subducting slabs is a manifestation of mantle convection. Without mantle convection you could not get subducting slabs. That is because subducting slabs IS mantle convection. A force of plate tectonics is slab pull, this is just one component of mantle convection that drives plate tectonics - this IS subducting slabs. Without mantle convection you could not get subducting slabs. Subducting slabs are fact, to deny them would be sheer ignorance. Therefore mantle convection is undeniable and is strongly coupled to plate tectonics.

    To suggest that glaciation causes mantle convection is verging on the ridiculous, but that is what you would need to do (and to prove) to convince me that glaciation drives plate tectonics.
     
  7. May 19, 2009 #6
    I'm not saying that mantle convection cannot move plates. I'm sure it can. And that might cause a stable smooth and gradual movement, that is predictable over MA+ timescales. I'm concerned that magma containing high percentages of water is far more fluid than the deep mantle, fairly standard in plate boundarys, volcanic chains on the ocean floor etc. That these are not isolated at all but all a branching web connected to many large magma bubbles. Like the 1000km dia one under me right now that has produced supervolcano eruptions in 50+ Caldera zones some 100 times in glacial maxes in the last million years alone. Much to me seems to indicate major volcanic events and periods are linked to max glaciation timing and then subduction of big landmasses timed with big deglaciations. That plates are hammering together and dropping slivers on the recoil part of the cycle at continental-oceanic plate boundaries. Subduction not a smooth process but a smash and swallow cycle with minor cyclic periods of ~10ka and major 100ka for last 3ma.

    Its a nice fluffy comfortzone to think that geological processes are slow, steady, predictable.
    That the horizontal and vertical movements of crust as we have had the privilege of knowing for a couple of decades should be complacently accepted as motions that have not changed significantly for 10s of thou to millions of years is a blanket I have personally been happy to swaddle in for 3 decades. But now I'm seeing this as very dangerous complacency.

    Trying to incorporate the depth of data thats now becoming available into the simple theories and models formulated before observations of the ocean floor existed at all is shattering my previous beliefs in steady smooth convection driven tectonics in the last ~30MA. And the last ~2MA is looking more ragged and glacial cycle dominated than ever before to me.

    Any comments on the Paper I linked above? explanations of the seafloor features I linked to?
    Anyone?
    Scary I know. But if we are lighting the fuse on tectonic chaos with big sudden deglaciation as we are currently initiating then at least the people with brains should have a chance to be prepared and survive. Then they can make sure its a lesson we don't have to suffer again.
     

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  8. May 20, 2009 #7
    I am confused, you seem to be back tracking, now you are saying that deglaciation is assoicated with increased volcanism? So in fact tectonics is not "driven by ice mass changes" as your title would suggest (a simple consideration of the forces involved would surely debunk this hypothesis). Furthermore your "evidence" is not convincing, sure there are fractures and other topographic features of the ocean sea floor -- so what? Those can be explained by standard plate tectonics a hell of a lot more simply than your "Decreasing glaciation sucks out the stuffing" hypothesis (which to me seems absurd). Incidentally, your assertion that the standard model of plate tectonics cannot cope with catastrophic changes is completely misplaced, on the contrary, plate tectonics neatly explains the global distribution of volcanism (not just geographic locations but also the associated geochemical and geophysical data) and seismicity which are hardly smoothly varying phenomena.
     
  9. May 20, 2009 #8
    It may be that the long term carbon cycle is not a steady conveyorbelt but a periodic system. The usual exit from glacial periods might be from CO2 expelled through volcanism from recycled crust by the pressures exerted by ice masses on antarctica, sth america, greenland, nth america and nth europe in the last 2-30 MA time period. This is what I think is very important for us to consider. That we are breaking this apparent cycle with CO2 inputs that vastly exceed its natural and repetitive bounds with our 200yr 1000gton carbon bomb to date is scary however you look at it.
    We need to consider what feedbacks this might be invoking. And to what extent the climate that is dependant on these factors may be involved in the geodynamic processes. If Glaciation forces volcanic behaviour, and through co2 release this causes deglaciation, and this then cycles back to reglaciation...
    We need to understand how interelated these processes are. And what the effects of rapid deglaciation are is the question that is most important right now. Because we have not seen an event on this planet that compares with the rapid change we have now initiated at least in 65MA. The best comparisons are the 28MA bp deglaciation of antarctica, and the PETM 56MA bp with simular atmospheric carbon spike in magnitude, but divided between 2 1000yr periods 20000yrs apart.
    We could look at the pulse, with a comparison of major volcanism and glacial cyclicity. Anyone keen to look at that?
     
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