Nav: Home

Atoms under the mantle

March 06, 2007

At a depth of 2900 kilometres, the layer between the Earth's mantle and its core has always intrigued geophysicists because they are unable to explain the seismic data it generates. Researchers in the Solid State Structure and Properties Laboratory (CNRS/Université Lille 1/Lille National School for Advanced Chemistry) have studied its deformation which influences convection movements within the mantle or even those by tectonic plates. Despite the inaccessibility of this layer and the extreme conditions which prevail, they have succeeded in modelling the defects responsible for its deformation. These results, obtained using a novel approach which combines numerical calculus and quantum mechanics, constitute the first step towards modelling deformation of this layer and its effects on the mantle. They are published in the March 1st, 2007 issue of Nature.

Direct access to the Earth's interior is impossible: even the deepest bore holes are only scratches on the surface. Our knowledge of the Earth's interior comes from studying the seismic waves which propagate through the Earth from the focus of an earthquake. We know today that the Earth is divided into layers. The crust on which we live only represents a thin skin. The main shell is called the mantle, a layer made up of solid rock which extends to a depth of up to 2900 kilometres. It surrounds the liquid core which in turn shields the solid core, with a radius of 1200 kilometres. The interface between the mantle and the core, called the D" layer, has long intrigued geophysicists because they are unable to explain the seismic data it generates.

From a mineralogical point of view, 80% of the terrestrial mantle is made up of a silicate (MgSiO3) with a crystalline, perovskite structure. This mineral accounts for half of the Earth's mass. In 2004, several teams (notably from Japan) showed that perovskite became unstable near the core-mantle interface to form a new phase, or post-perovskite. Could post-perovskite deformation explain the seismic signature of the D" layer?

Patrick Cordier and his colleagues based themselves on this hypothesis. But how could a crystalline solid be deformed? The answer lies at the atomic scale: the crystals contain defects called dislocations, which are responsible for plastic deformation. Although their structure is relatively well understood in simple materials such as certain metals (copper, aluminium, etc.), the scientists had little knowledge of the structure of dislocations in complex materials such as minerals, particularly under extreme conditions of pressure. The team in Lille employed a novel approach: instead of reproducing the conditions prevailing inside the Earth in the laboratory, they used a simulation method by injecting the results of quantum mechanics into a numerical model to render it simpler. They are the first to have thus modelled dislocations at the atomic scale for complex materials under extremely high pressure.

The dislocations of which we now know the structure move within the crystal and interact between each other. Scientists thus have access to calculation codes which allow them to describe these interactions. They now want to clarify the behaviour of each grain of crystalline matter, then of the rock and beyond that, of the mantle. A dream? Maybe not. The advances achieved in recent years allow us to be optimistic. So perhaps our voyage to the centre of the Earth will be numerical.
-end-
Figure 1 - Model of a dislocation in the post-perovskite phase of the D" layer. This type of dislocation is responsible for the deformation of this layer, affecting convection movements within the mantle perceived via plate tectonics. © Patrick Cordier - CNRS 2007 (this image is available from the CNRS photo library, on 01 45 07 57 90, phototheque@cnrs-bellevue.fr)

BIBLIOGRAPHY

Implications for plastic flow in the deep mantle from modelling dislocations in MgSiO3 minerals, Philippe Carrez, Denise Ferré & Patrick Cordier, Nature, March 1st, 2007.

CONTACTS

Researcher contact
Patrick Cordier
T 03 20 43 43 41
Patrick.cordier@univ-lille1.fr

Press contact
Claire Le Poulennec
T 01 44 96 49 88
Claire.le-poulennec@cnrs-dir.fr

CNRS

Related Quantum Mechanics Articles:

Understanding mechanics and materials though evolution and biomaterials
Studying the evolution of bodily processes millions of years ago as well as the properties of today's biomaterials could improve soft robotics design and inform materials science research.
USTC realizes the first quantum-entangling-measurements-enhanced quantum orienteering
Researchers enhanced the performance of quantum orienteering with entangling measurements via photonic quantum walks.
A convex-optimization-based quantum process tomography method for reconstructing quantum channels
Researchers from SJTU have developed a convex-optimization-based quantum process tomography method for reconstructing quantum channels, and have shown the validity to seawater channels and general channels, enabling a more precise and robust estimation of the elements of the process matrix with less demands on preliminary resources.
What a pair! Coupled quantum dots may offer a new way to store quantum information
Researchers at the National Institute of Standards and Technology (NIST) and their colleagues have for the first time created and imaged a novel pair of quantum dots -- tiny islands of confined electric charge that act like interacting artificial atoms.
In leap for quantum computing, silicon quantum bits establish a long-distance relationship
In an important step forward in the quest to build a quantum computer using silicon-based hardware, researchers at Princeton have succeeded in making possible the exchange of information between two qubits located relatively far apart -- about the length of a grain of rice, which is a considerable distance on a computer chip.
Artificial intelligence algorithm can learn the laws of quantum mechanics
Artificial intelligence can be used to predict molecular wave functions and the electronic properties of molecules.
A new quantum data classification protocol brings us nearer to a future 'quantum internet'
A new protocol created by researchers at the Universitat Autònoma de Barcelona sorts and classifies quantum data by the state in which they were prepared, with more efficiency than the equivalent classical algorithm.
Bridge between quantum mechanics and general relativity still possible
An international team of researchers developed a unified framework that would account for this apparent break down between classical and quantum physics, and they put it to the test using a quantum satellite called Micius.
'Poor man's qubit' can solve quantum problems without going quantum
Researchers have built and demonstrated the first hardware for a probabilistic computer, a possible way to bridge the gap between classical and quantum computing.
Cracking a decades-old test, researchers bolster case for quantum mechanics
At upcoming FiO + LS conference, researchers will discuss creative tactics to get rid of loopholes that have long confounded tests of quantum mechanics.
More Quantum Mechanics News and Quantum Mechanics Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Teaching For Better Humans 2.0
More than test scores or good grades–what do kids need for the future? This hour, TED speakers explore how to help children grow into better humans, both during and after this time of crisis. Guests include educators Richard Culatta and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#556 The Power of Friendship
It's 2020 and times are tough. Maybe some of us are learning about social distancing the hard way. Maybe we just are all a little anxious. No matter what, we could probably use a friend. But what is a friend, exactly? And why do we need them so much? This week host Bethany Brookshire speaks with Lydia Denworth, author of the new book "Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond". This episode is hosted by Bethany Brookshire, science writer from Science News.
Now Playing: Radiolab

Dispatch 3: Shared Immunity
More than a million people have caught Covid-19, and tens of thousands have died. But thousands more have survived and recovered. A week or so ago (aka, what feels like ten years in corona time) producer Molly Webster learned that many of those survivors possess a kind of superpower: antibodies trained to fight the virus. Not only that, they might be able to pass this power on to the people who are sick with corona, and still in the fight. Today we have the story of an experimental treatment that's popping up all over the country: convalescent plasma transfusion, a century-old procedure that some say may become one of our best weapons against this devastating, new disease.   If you have recovered from Covid-19 and want to donate plasma, national and local donation registries are gearing up to collect blood.  To sign up with the American Red Cross, a national organization that works in local communities, head here.  To find out more about the The National COVID-19 Convalescent Plasma Project, which we spoke about in our episode, including information on clinical trials or plasma donation projects in your community, go here.  And if you are in the greater New York City area, and want to donate convalescent plasma, head over to the New York Blood Center to sign up. Or, register with specific NYC hospitals here.   If you are sick with Covid-19, and are interested in participating in a clinical trial, or are looking for a plasma donor match, check in with your local hospital, university, or blood center for more; you can also find more information on trials at The National COVID-19 Convalescent Plasma Project. And lastly, Tatiana Prowell's tweet that tipped us off is here. This episode was reported by Molly Webster and produced by Pat Walters. Special thanks to Drs. Evan Bloch and Tim Byun, as well as the Albert Einstein College of Medicine.  Support Radiolab today at Radiolab.org/donate.