Researchers find links between magnetic field inversions, mantle convection and tectonics

Jul 29, 2012

On a time scale of tens to hundreds of millions of years, the geomagnetic field may be influenced by currents in the mantle. The frequent polarity reversals of Earth's magnetic field can also be connected with processes in the mantle. These are the research results presented by a group of geoscientists in the new advance edition of Nature Geoscience on July 29, 2012. The results show how the rapid processes in the outer core, which flows at rates of up to about one millimeter per second, are coupled with the processes in the mantle, which occur more in the velocity range of centimeters per year.

The international group of scientists led by A. Biggin of the University of Liverpool included members of the GFZ German Research Centre for Geosciences, the IPGP Paris, the universities of Oslo and Utrecht, and other partners.

It is known that the Earth's magnetic field is produced by convection currents of an electrically conducting iron-nickel alloyin the , about 3,000 kilometers below the earth's surface. The is highly variable, there are changes in Earth's magnetic field on a multitude of spatial and temporal scales. Above the is the , the rock in which behaves plastically deformable due to the intense heat and high pressure. At the boundary between Earth's core and mantle at 2900 km depth there is an intense heat exchange, which is on the one hand directed from the Earth's core into the mantle. On the other hand, processes within Earth's mantle in turn also affect the heat flow. The interesting question is how the much slower flow in the solid mantle influences the heat flow and its at the core-mantle boundary, and how this will affect the Earth's magnetic field which is produced due to the much faster currents in the Earth's core.

Key variable heat transfer

"The key variable is the heat flow. A cooler mantle accelerates the flow of heat from the hot core of the Earth, and in this way alters the also heat-driven convection in the Earth's core", said Bernhard Steinberger of the GFZ for Geosciences. "Ocean floor sinking into the mantle due to tectonic processes can lead to cooling in the mantle. They cause at these sites an increased into the cooler parts, namely until they have been heated to the ambient temperature." That might take several hundred million years, however.

Conversely, the hot core of the Earth leads to the ascent of heated rocks in form of large bubbles, so-called mantle plumes that separate from the core-mantle boundary and make their way up to the surface of the earth. This is how Hawaii came into existence. This increases the local heat flux out of the earth's core and in turn modifies the generator of the geomagnetic field.

Reversals of the magnetic field

In the Earth's history, polarity reversals of the geomagnetic field are nothing extraordinary. The most recent took place only 780 000 years ago, geologically speaking a very short period of time. The research team was able to determine that in the period of 200 to 80 million years before present, reversals initially happened more often, namely up to ten times in hundred million years. "Surprisingly, these reversals stopped about 120 million years ago and were absent for nearly 40 million years," explains GFZ scientist Sachs. Scientists presume that the reason for this is a concurrent reorientation of the whole mantle and crust with a shift in the geographic and magnetic poles of about 30°. Known as "true polar wander", thisprocess is caused by a change in density distribution in the mantle. If it increases the heat flux in equatorial regions, it would presumably lead to more frequent field reversals, if it decreases it, the field reversal might not occur.

Looking to the future

According to current knowledge, therefore, an influence of plate tectonics and mantle convection on the Earth's magnetic field seems quite possible. The article also shows, however, that further research is still needed for a better understanding of these relationships. In particular, more episodes of "true polar wander" should be derived from paleomagnetic data, and it should be determined whether these are usually associated with an altered behavior of the (e.g. frequency of field reversal). Also, future models for the generation of the geomagnetic field should investigate the influence of the spatial and temporal variation of the heat flux at the core-mantle boundary in more detail.

Explore further: Thousands of intense earthquakes rock Iceland

More information: J. Biggin et al., "Possible links between long-term geomagnetic variations and whole-mantle convection processes", Nature Geoscience, Vol. 5, August 2012, doi:10.1038/NGEO1521

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User comments : 37

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Ophelia
5 / 5 (1) Jul 29, 2012
"The most recent took place only 780 000 years ago, geologically speaking a very short period of time. The research team was able to determine that in the period of 200 to 80 million years before present, reversals initially happened more often, namely up to ten times in hundred million years."

Let's see, is ten times in 100 million years (once per 10 million years) "more frequent" than once in 780,000 years?

Actually, since the article doesn't really give any other time frame for numbers of reversals in numbers of years - except none for 40 million years - no comparison should have been made, but that gap didn't come up until after it had been made.

It would be nice if people who write these things would reread them.
TheWalrus
5 / 5 (1) Jul 29, 2012
The first time I read of Earth's magnetic field inversion was in the early '80s. That article said there was a strong correlation with the solar system's orbit around the Milky Way, and speculated that the regular periodicity of the inverrsion might be influenced by some magnetic phenomena in the galaxy itself.

Anyone else know anything about this?
technodiss
5 / 5 (1) Jul 29, 2012
@walrus. the eighties were a weird time for science (and everything else). but what you're talking about sounds like the new age pseudo-science that 2012ers base their nonsense on. i'm sure that even then, this wasn't considered a valid theory.
TheWalrus
5 / 5 (3) Jul 29, 2012
@walrus. the eighties were a weird time for science (and everything else). but what you're talking about sounds like the new age pseudo-science that 2012ers base their nonsense on. i'm sure that even then, this wasn't considered a valid theory.


Then again, I'm not a scientist. Like most of us here, I'm an interested layman.

I like being corrected. I'd much rather be shown that I'm wrong, than believe falsehoods.

Unlike {ahem} some other commenters...
nigel_beardwood
5 / 5 (2) Jul 30, 2012
I'm still trying to get past the two, 2 typos in the Title.
ormondotvos
5 / 5 (1) Jul 30, 2012
Yeah, I just read the whole article to find out what the definition of concections was!
Satene
2 / 5 (4) Jul 30, 2012
there was a strong correlation with the solar system's orbit around the Milky Way, and speculated that the regular periodicity of the inversion might be influenced by some magnetic phenomena in the galaxy itself

In my opinion it's the influence of dark matter distribution within our galaxy - it's concentration is higher at the center of galactic plane and the gravitational shadow of Great Dark Rift may play its role too. The increased concentration of neutrinos in dark matter accelerates the decay of radioactive elements inside of Earth mantle, which may cause shift of convection between core and the surface of Earth.
antialias_physorg
3.3 / 5 (4) Jul 30, 2012
That article said there was a strong correlation with the solar system's orbit around the Milky Way,

Orbit around the Milky way is on the order of 200-250 million years.
Passing through the 'galactic plane' happens, depending on how you define it, every year or once in 30 million years (by the definition used for the latter we're currently about 50 light years out of the plane)

Geomagnetic reversals happen every 1 to 10 thousand years. So no, no correlation there.
Satene
5 / 5 (1) Jul 30, 2012
Geomagnetic reversals happen every 1 to 10 thousand years
The latest geomagnetic reversal (the BrunhesMatuyama reversal) occurred 780,000 years ago. http://en.wikiped...reversal
antialias_physorg
4 / 5 (4) Jul 30, 2012
Thanks, I got the wrong cite for that one. But looking at the complete graph:
http://en.wikiped...reversal
It seems that geomagnetic reversals are much more frequent than passing though the plane (or galactic cycles). There were about 20 reversals in the past 5 million years (so on average one every 250k years) - and the reversals seem to be vary wildly in duration from 100k to 800k years.
Satene
2.3 / 5 (4) Jul 30, 2012
Which is the reason, I presume, the passing trough galactic arms gravitational shadow of massive parts of Milky Way galaxy may play its role too (1). Terrestrial temperatures are postulated to increase during the perigalactic passage and decline near the apogalac tic point, producing long-term climatic cycles (2).
antialias_physorg
3.4 / 5 (5) Jul 30, 2012
Which is the reason, I presume, the passing trough galactic arms

But we aren't passing through galactic arms.

gravitational shadow

What does that even mean? Gravity isn't blocked by anything (least of all mass).

Terrestrial temperatures are postulated to increase during the perigalactic passage and decline near the apogalac tic point,

Which is just a lot of bunk. And even if - that is on the orders of many millions of years. Nowhere near the 250k (or even 800k) mark.

kevinrtrs
1.7 / 5 (6) Jul 30, 2012
It is known that the Earth's magnetic field is produced by convection currents of an electrically conducting iron-nickel alloyin the liquid core, about 3,000 kilometers below the earth's surface.

I wish people would stop making these "absolute truth" statements and be more open and honest in their communications. Right now, the statement should read "It is thought that..." because the mathematical modelling is just horrendously complex. So complex in fact that most researchers shy away from it. No one is really sure about how this dynamo is really supposed to operate.
To make it more real - there is a dearth of predictions coming forth from such modelling. And with very good reason.

This is one of the reasons for the current research named in the article - looking at all kinds of influences on supposed dynamo generation of the magnetic field.

Blakut
not rated yet Jul 30, 2012
Convection cell within a convection cell: concection.
Satene
1 / 5 (3) Jul 30, 2012
There are many other possible sources of dark matter (neutrinos). Such a neutrinos may be ejected with central area of Milky Way or they can be trapped with nearby massive dense object (1, 2).
Blakut
3 / 5 (2) Jul 30, 2012
Neutrinos are ruled out as DM by the Big Bang Nucleosynthesis model. There just isn't such a source for them (or wasn't) in the past. Neutrinos produced by BBN would also be hot aka fast, so not possible to trap.
Satene
2.6 / 5 (5) Jul 30, 2012
IMO the neutrinos form just a portion of dark matter (in my model they're a solitons of gravitational waves in similar way, like the photons are solitons of light waves). IMO the largest portion of dark matter is simply volume area of increased density of CMBR noise, the neutrinos represent the most massive portion of it similar to foam covering the tidal waves. But this CMBR noise is formed with gravitational waves coming from all directions with superluminal speed and they may be shielded with massive objects. This shielding is manifesting itself like the gravity and the shielding of this shielding with nearby massive objects like so-called cold dark matter.
Satene
1.8 / 5 (5) Jul 30, 2012
Neutrinos produced by BBN would also be hot aka fast, so not possible to trap.
I don't believe in Big bang model, but the neutrinos formed during various matter transforms would be thermalized with CMBR noise gradually, because they're lightweight. And vice-versa, during various conjunctions the neutrinos may emerge from empty space with quantum processes. The dark matter may be dynamically formed between galaxies and massive objects like fibbers of dark matter. Which is the of reason, why I consider the conjunction of Dark Rift with solar system as the one possible source of undergoing climatic and geomagnetic changes.
Satene
1.7 / 5 (6) Jul 30, 2012
We should consider large amount of facts to get the whole picture. What we know in this moment for example is: 1) the solar system is entering large cloud of interstellar gas 2) the geomagnetic poles are migrating and face the reversal 3) the global warming occurs at most planets of solar system 4,5) the gravity constant and speed of light fluctuate toward lower values 6) The iridium SI prototypes dilate and lose mass 7) The geovolcanic activity is on the rise 8) Global warming exhibits heat content anomaly (oceans are warming faster than the atmosphere) 9) The neutrinos affect the speed of radioactive elements decay 10) Moon's eccentricity has increased at an anomalous rate, etc..

This article may be of some interest for someone too: NASA geophysicists found natural cycles to Earth's warming that correlate to movement of liquid iron in Earth's outer core -- up until 1930..
antialias_physorg
3.4 / 5 (5) Jul 30, 2012
We should consider large amount of facts

Good idea.
the solar system is entering large cloud of interstellar gas

Where do you get that from?
he geomagnetic poles are migrating and face the reversal

Where do you get that from?
the global warming occurs at most planets of solar system

Where do you get that from?
the gravity constant and speed of light fluctuate

Where do you get that from?
The iridium SI prototypes dilate and lose mass

Where do you get that from? (Note that most all of the copies don't)
The geovolcanic activity is on the rise

Strongly correlated to population increase. This may just be an issue of more being reported rather than more being present.
Global warming exhibits heat content anomaly

This surprises you? Most light passes the atmosphhere. All that passes (and doesn't get reflected) is absorbed. So OF COURSE will oceans warm faster than air (Ever notice that on a hot day the ground is warmer than the air?)
Satene
1.8 / 5 (5) Jul 30, 2012
Where do you get that from?
From peer-reviewed articles and from the news which are reporting about it..
this may just be an issue of more being reported..
Or maybe not
So OF COURSE will oceans warm faster than air
Not in Arrhenius theory, where the global warming comes from carbon dioxide in the air, whereas the concentration of carbon dioxide in the seawater rather decreases.
Sepp
1 / 5 (5) Jul 30, 2012
"It is known that the Earth's magnetic field is produced by convection currents of an electrically conducting iron-nickel alloyin the liquid core, about 3,000 kilometers below the earth's surface."

It would be much more correct to say: "It is assumed that..."

No one really knows - yet. We have only theories, no direct examination of the interior of the earth.
antialias_physorg
4 / 5 (4) Jul 30, 2012
What I'm saying here is: If you are trying to 'consider large amounts of facts' you should check that they are facts.
What you have listed are for the overwhelming part untested speculations and the rest are downright fabrications that are just plain false.

So yes: Consider the facts. By all means. Do.
Allex
4.6 / 5 (5) Jul 30, 2012
1) the solar system is entering large cloud of interstellar gas

Which must be invisible (undetectable) since not a single astronomical measurement has confirmed it. Provide a source for this revelation.
2) the geomagnetic poles are migrating and face the reversal

Like they have for hundreds of millions of years. Is this surprising?
3) the global warming occurs at most planets of solar system

Provide a solid database or any type of verifiable information from all those planets. I'm very keen on seeing climate records from Neptune or Venus.
4,5) the gravity constant and speed of light fluctuate toward lower values

Provide a source for these revelations. Einstein is spinning in his grave.

Actually provide any sources for all your ridiculous claims. I smell BS.
vidyunmaya
1 / 5 (5) Jul 30, 2012
sub: Pridhveem Viswam Asya Dharineem-
heart of the Universe introduces the Magnetic field Links to Earth region -100AU. it is a reality where science needs to take cognisance.CENTRE OF THE UNIVERSE-HEART OF THE UNIVERSE-Nov 2006 - TXU 1-364-245 -The Science in Philosophy- Pridhvi Viswam Asya Dharineem Cosmos yoga vision series-II- cover upto 10^5 L Y
see Cosmlogy Vedas Interlinks
barakn
1 / 5 (1) Jul 30, 2012
1) the solar system is entering large cloud of interstellar gas

Which must be invisible (undetectable) since not a single astronomical measurement has confirmed it. Provide a source for this revelation.

References to the Local Interstellar Cloud or LIC can be found in this http://sredfield....ar02.pdf and thousands of other papers.
Bewia
1.6 / 5 (7) Jul 30, 2012
Actually provide any sources for all your ridiculous claims
The problem is, the people like you spend whole hours here with twaddling, but they don't remember even few months old articles. They're still feel competent to oppose me, although they're nothing but dumb ignorant, who even cannot use the Google for verification of facts.
1) the solar system is entering large cloud of interstellar gas.. since not a single astronomical measurement has confirmed it There are many evidence for it - both direct, both indirect. For example the frequency of asteroid and cometary impacts at the Sun, Jupiter or Saturn planet raised recently by many orders of magnitude, because this massive clouds affects the paths of massive objects and drags them into our solar system.
Bewia
1.6 / 5 (7) Jul 30, 2012
For example, www.nascom.nasa.g...1024.jpg]this is how[/url] the neighborhood of the Sun appears occasionally. These observations are never getting published at news servers like PhysOrg for not to scare the people - but it doesn't mean, they doesn't exist. The consequence is, I'm living in quite different alternative reality, than most of visitors here and it has no meaning to spend my time with discussions about it here. It's like the explanation of principle of rocket to some naive group of tribal people: if they've no informational background, they can never get the connections. The ignorance is the mother of the religion - you shouldn't consider, just the fact you're living in 21st century can protect you from religious ignorance, when you're avoiding the facts systematically.
Bewia
2 / 5 (4) Jul 30, 2012
The correct link is here - the comment editor cripples the links with some URLs sohowww.nascom.nasa.g...1024.jpg
Bewia
1.8 / 5 (5) Jul 30, 2012
The correct link is here - the comment editor cannot handle some URLs http://is.gd/VJK1Q9
Allex
4.2 / 5 (5) Jul 30, 2012
They're still feel competent to oppose me, although they're nothing but dumb ignorant, who even cannot use the Google for verification of facts.

Ad hominem is the weapon-of-choice of creationist, politicians and plain ol' morons. Which one are you?:) I could care less about the opinion of a individual your post editing skills.
http://news.scien...org(...)

Contrary to you I read the article (you should too because clearly you have not) and there is not a single notion about the increase of impacts due to a cloud of gas.

Or for morons like you - "The reason we haven't seen impacts before is simple: digital cameras and image processing techniques have only become easily available to amateurs in the last ten years". Should an adult explain to you what does the citation mean?

Tell me where does it say a cloud of interstellar gas is responsible for it? Except in comments, which intellectually handicapped like yourself have posted.
Allex
3.7 / 5 (6) Jul 30, 2012
I'm living in quite different alternative reality

Oh I'm sure of that, but I prefer the one reality (you know, the REAL world) over any delusion. I wish people like you would too.
barakn
3.4 / 5 (5) Jul 31, 2012
More fatuous twaddle from Zephir. The SOHO coronagraph obviously shows slow-moving, non-symmetrical, macroscopic particles, some rotating, moving from upper right to lower left through the field of view of the coronagraph, one even bouncing off the occulter pylon. These are probably bits of paint or ice crystals released from the SOHO craft itself.
I'm living in quite different alternative reality
At least we can agree on that.
Satene
1.8 / 5 (5) Jul 31, 2012
Provide a source for these revelations.
I linked Nature journal (whole editor note was dedicated to this phenomena) - but my post was deleted from here. So you should help yourself - it's not my task to educate people here. We can reverse your problem with information sources easily: provide the evidence, that values of light speed and gravitational constant didn't change during last years.
Satene
1.8 / 5 (5) Jul 31, 2012
there is not a single notion about the increase of impacts due to a cloud of gas
This is just how the contemporary community of so-called "experts" is working. We have an experts for observation of interstellar clouds and the experts for observation of asteroids. Until new group of experts is not established, you cannot get the connection about link of these two phenomena.
The reason we haven't seen impacts before is simple: digital cameras and image processing techniques have only become easily available to amateurs in the last ten year
The official data are censored in the same way, like observations of anomalous objects near Sun, etc. The official science avoids all exceptions violating established paradigms instinctively
Allex
not rated yet Aug 02, 2012
The official science avoids all exceptions violating established paradigms instinctively

Conspiracy is the magic word that makes every loon seem like a soldier fighting the good war. NOPE. It makes you seem even more ridiculous.
barakn
not rated yet Aug 04, 2012
Satene/Zephir - I'm not surprised that you're ignoring a post that revealed your hush-hush SOHO image of some unspecified cosmic wonder was just spacecraft debris, but I am disappointed. I'd love to see how you worm out of that one.