News

IT for Augury

Because we work with large digital datasets (our results from our numerical models), we need to have some tools to make the best out of them. One goal is to create a database of all our calculations, that we can explore in order to avoid computing the same thing for the second time, or to analyse a computation already done. Sebastien Aurousseau was hired for 4 1/2 months to develop AuguReach, the tool to generate the database, automatically update it and search for parameterizations. It now works and it is a great help for us. In the future, we should be able to share our calculation results with this tool. For now, the security is not at the level we can do it outside the institution. Sebastien worked with Naïma to provide us a SVN server for our codes, and a DokuWiki for all our softwares and eventually beyond. We want to have collaborative tools and take care of the digital heritage we are building.

Yann was an intern for 3 months, coming from an undergraduate program of computer sciences. He worked on developing a software to automatically detect plate polygons in our calculations with plate-like behavior.

We were lucky to have them. In September their IT spirit will be gone and we will miss them.

Sébastien and Yann

Spring visits

May and June were busy for the AUGURY team in Lyon. We had the visit of Edward Garnero from Arizona State University for one month. It was the occasion for everyone of us to discuss and work on the deepest mantle, but also the structure and dynamics of the ocean lithosphere. During his stay, we invited also Shijie Zhong from Boulder for a day. We talked about low velocity provinces in the lower mantle with the geodynamics people in Lyon, but also convection modeling with plates.

Eddie started a little book for us that I share here: Seismology for geodynamicists S4G (click on S4G to download the PDF file).

It was great for us to know more about how seismological observations are made, how they can help us to understand mantle flow and deep mantle processes. To be continued.

Nicolas Coltice visited the CEED in Oslo, where Tobias Rolf and Grace Shephard, collaborating in the AUGURY project are currently working. The CEED is a very special place to our subject of interest since it is one of the goals of the group to reconstruct past mantle motion and surface tectonics.

Then Marie Bocher, Martina Ulvrova and Nicolas Coltice joined Paul Tackley in Zurich for the PACS meeting early in June. Alexandre Fournier from Paris, co-advising the PhD thesis of Marie Bocher, was there too. We had the chance to present our progress and learn from the computational science community, and we had a good time as a group.

EGU2015 in Vienna

The group from Lyon in front of the meeting Hall

Between the 12th and the 17th of April, many of the people working in the AUGURY project went to Vienna to present their work for the European Geophysical Union meeting. It is a big event in the European community of Earth Sciences. For us, it was the first meeting where we could present our new works after a year the project started.

Léa explaining to Shijie Zhong her work on convection reconstructions.

Martina explaining how she models convection with continents with surface topography.

Léa and Martina presented their posters and had many insightful interactions. The poster sessions were full of people and it was a good time for them to share their research.

Claire giving answering questions after her talk.

It was also Claire’s first talk and she had a convincing first experience. She had questions on how plate tectonics works in her convection models, but also on other planets.

I also gave a talk on Tuesday and enjoyed sessions on data assimilations which where new for me.

Tobias in front of one of his posters.

Other members were present like Paul Tackley, Dietmar Müller, Charitra Jain and Tobias Rolf. It was a good time to interact on the project and beyond.

Dr Léa Bello, Bravo!

Léa Bello, the first member of the AUGURY team, completed her PhD on the 16th of January. She defended her thesis on predictability of mantle convection models in from of a diverse and interested committee (Luce Fleitout, Carolina Lithgow-Bertelloni, Taras Gerya, Laurent Husson and Yanick Ricard).

It was a very good moment for all the team. Congratulation to her for what she did. It was really with her and with her work that we built the foundation of what is to come.

I am very proud of her and wish her well for the future. It is great to have her for several more months in Lyon.

Here is a picture of her in the Montparnasse subway section, in front of a mantle convection picture she actually made millions of people have seen (kind of rare for us geodynamicists).

– Nicolas.

AUGURY workshop @ Valflaunès – Nov 10-12

The first AUGURY workshop took place this fall in the region of Pic Saint Loup, in Valflaunès, France. Eleven people attended the workshop: Charitra Jain, Antoine Rozel and Paul Tackley from ETH Zurich, Kayla Maloney from EarthByte Sydney, Grace Shephard and Tobias Rolf from University of Olso and Léa Bello, Marie Bocher, Claire Mallard, Martina Ulvrova and Nicolas Coltice from LGL Lyon.

Group picture with Pic Saint Loup and Hortus in the back

The workshop started with everyone presenting the work in progress on convection modeling, plate reconstructions and data assimilation for the Earth’s mantle. It made an interesting mix to select several topics that meet when it comes to reconstructing the 3D structure of the mantle and surface tectonics together.

Presentation session on the first day.

With all the information of  a dense first day, we brainstormed to build smaller groups working on focused topics for the next two days. The ‘Laptop sessions’ took place in different rooms of Gîtes du chateau de Valflaunès, and the group is now set for new plans on free surface, continents in convection models, plate tectonics of convection models, grain size and a few other topics.

Laptop sessions on the next days

The three days offered the occasion of sharing informations, techniques and making plans for the near future. It was also a good time for everyone, and the possibility to meet each other (over a good karaoke 😉 ). The group expressed his will to renew this very positive experience for research and group bonding.

Last lunch outside

Photos by Charitra Jain.

L’équipe AUGURY dans Sciences pour tous

Le portail de diffusion des savoirs de l’Université Lyon 1 propose un article sur l’équipe AUGURY que vous pouvez trouver ici : http://sciencespourtous.univ-lyon1.fr/les-paves-terre/

Photo : Eric Le Roux

New paper in Nature on early continents kick starting plate tectonics

The slow gravitational collapse of early continents could have kick-started transient episodes of plate tectonics until, as the Earth’s interior cooled and oceanic lithosphere became heavier, plate tectonics became self-sustaining.

See Patrice F. Rey, Nicolas Coltice, Nicolas Flament. Spreading continents kick-started plate tectonics. Nature, 2014; 513 (7518): 405 (http://www.nature.com/nature/journal/v513/n7518/full/nature13728.html) for more.

Stresses acting on cold, thick and negatively buoyant oceanic lithosphere are thought to be crucial to the initiation of subduction and the operation of plate tectonics, which characterizes the present-day geodynamics of the Earth. Because the Earth’s interior was hotter in the Archaean eon, the oceanic crust may have been thicker, thereby making the oceanic lithosphere more buoyant than at present, and whether subduction and plate tectonics occurred during this time is ambiguous, both in the geological record and in geodynamic models. Here we show that because the oceanic crust was thick and buoyant, early continents may have produced intra-lithospheric gravitational stresses large enough to drive their gravitational spreading, to initiate subduction at their margins and to trigger episodes of subduction. Our model predicts the co-occurrence of deep to progressively shallower mafic volcanics and arc magmatism within continents in a self-consistent geodynamic framework, explaining the enigmatic multimodal volcanism and tectonic record of Archaean cratons. Moreover, our model predicts a petrological stratification and tectonic structure of the sub-continental lithospheric mantle, two predictions that are consistent with xenolith5 and seismic studies, respectively, and consistent with the existence of a mid-lithospheric seismic discontinuity. The slow gravitational collapse of early continents could have kick-started transient episodes of plate tectonics until, as the Earth’s interior cooled and oceanic lithosphere became heavier, plate tectonics became self-sustaining.

In the news:

http://theconversation.com/what-a-crack-up-hefty-continents-got-tectonic-plates-moving-31686

https://news.yahoo.com/gravity-moved-continents-early-earth-171847198.html

http://www.iflscience.com/environment/spreading-continents-kick-started-plate-tectonics-billions-years-ago

http://phys.org/news/2014-09-plate-tectonics-earth-plates-motion.html

http://www.sciencedaily.com/releases/2014/09/140917131814.htm

http://www.popularmechanics.com/science/environment/how-plate-tectonics-got-kick-started-17217679

http://www.sciencecodex.com/what_set_the_earths_plates_in_motion-141868

http://www.lyoncapitale.fr/Journal/Lyon/Actualite/Actualites/Sciences/Un-geo-physicien-lyonnais-publie-dans-Nature

http://www.techno-science.net/?onglet=news&news=13157

Featured article in International Innovation

To know everything about the AUGURY project, check the last issue of International Innovation.
You can download the PDF file for the article here: http://geologie.ens-lyon.fr/augur/?p=402

Marie and Claire at SEDI 2014 @ Shonan Village Center in Japan

Marie Bocher and Claire Mallard attended the 14th Symposium of SEDI, held in Japan from the 3 to 8 august. They presented their work in the poster session « Mantle-modelling and dynamics ».
Marie’s poster presents a new approach of sequential data assimilation for the joint reconstruction of mantle convection and surface tectonics, which consists in combining surface velocities and heat fluxes evolution with a mantle convection model to reconstruct the tectonic and interior evolution of the mantle. This method proved to be efficient in recovering both temperature and velocity fields of convection evolution, including the position and geometry of slabs and plumes in the lower mantle.

Claire’s poster introduced a new methodology to interpret and apply the tectonic theory on the surface of the mantle convection models and shows the preliminary results of its application. It shows that the plate tectonics theory can be applied to convection models with plate-like behaviour and that the plate topology in this case is comparable to that of the Earth.
Marie and Claire benefited from discussions about their work and had the opportunity to interact with colleagues. They came out of this conference more experienced and with some new ideas. It was their first international workshop. Marie and Claire acknowledge Gauthier Hulot (IPG Paris) and the travel support provided by CNRS/INSU.

Continents set the pace – News posted by ETH Zurich

A post on the ETH website about computing convection with plate-like behavior and continents, related to our paper in Geology on the evolution of seafloor spreading with continental growth.
Check the story here https://www.ethz.ch/en/news-and-events/eth-news/news/2014/01/continents-set-the-pace.html