Tag: student

New publication in Earth and Planetary Science Letters

Publications, TIMEleSS news

Gay et al, Transformation microstructures in pyrolite under stress: Implications for anisotropy in subducting slabs below the 660 km discontinuity (2023) Earth and Planetary Science LettersNew year, and new publication for the TIMEleSS team! Former timeless PhD student Jeff Gay is the first author of Transformation microstructures in pyrolite under stress: Implications for anisotropy in subducting slabs below the 660 km discontinuity, published in the February 15, 2023, issue of Earth and Planetary Science Letters. The publication is a result of a collaboration between partners at the Université de Lille (J. Gay, E. Ledoux, J. Chantel, S. Merkel), WWU Münster (N. Krug, C. Sanchez-Valle) with measurements at the Deutsches Elektronen-Synchrotron (A. Pakhomova, H.-P. Liermann).

The ‘660’ discontinuity marks the boundary between the upper and lower mantle and is located 660 km below our feet. The is discontinuity often associated with a phase transitions in pyrolite, a model rock composition for the Earth’s mantle. In addition, there are ubiquitous reports of seismic anisotropy below the ‘660’ which are difficult to explain from a mineralogical point of view.

In this study, we implement multigrain crystallography X-ray diffraction in the laser-heated diamond anvil cell in order to track microstructures induced by phase transitions at the pressure and temperature conditions of the discontinuity, around 24 GPa and 1900 K. Before the onset of transformation, pyrolite minerals such as garnet and ringwoodite are isotropic and do not contribute to seismic anisotropy.  After the transformation, bridgmanite, the most abundant mineral in the Earth, displays a strong preferred orientation, which we attribute to growth under stress. Other minerals such as davemaoite and ferropericlase are also considered.

The results are used to model anisotropy in a subducting slab, with a prediction of no anisotropy above the ‘660’ and up to 1.28% (0.08 km/s) shear wave splitting below the ‘660’ and provide details on how detailed wave forms can be used to understand the geometry of stress at those depths.

New publication in Frontiers in Earth Science

Publications, TIMEleSS news

Deformation of Polycrystalline MgO Up to 8.3 GPa and 1270 K: Microstructures, Dominant Slip-Systems, and Transition to Grain Boundary SlidingWe have a new publication! On May 9th, 2022, former TIMEleSS PhD student Estelle Ledoux published a new paper in Frontiers in Earth Science: Deformation of Polycrystalline MgO Up to 8.3 GPa and 1270 K: Microstructures, Dominant Slip-Systems, and Transition to Grain Boundary Sliding.

The work is a result of a collaboration between the Université de Lille and the University of Utah. We focus on polycrystalline periclase, the pure Mg end-member of the second-most abundant mineral in the Earth lower mantle, ferro-periclase, for which mechanical properties are important to understand flow and the dynamics of the Earth mantle.

we deform polycrystalline periclase at conditions ranging from 1.6 to 8.3 GPa and 875–1,270 K. We analyse the flow laws and microstructures of the recovered samples using electron microscopy and compare our observations with predictions from the literature. We identify a first mechanism for samples deformed at 1,270 K, attributed to a regime controlled by grain boundary sliding accommodated by diffusion, and characterized by a small grain size, an absence of texture, and no intracrystalline deformation. At 1,070 K and below, the deformation regime is controlled by dislocations. The samples show a more homogeneous grain size distribution, significant texture, and intracrystalline strains. In this regime, deformation is controlled by the ⟨110⟩{110} slip system and a combined ⟨110⟩{110} and ⟨110⟩{100} slip, depending on pressure and temperature.

Based on these results, we propose an updated deformation map for polycrystalline MgO at mantle conditions and discuss the implications for ferropericlase and seismic observations in the Earth’s lower mantle.

More details can be found in the open-access full reference of the study: E. E. Ledoux, F. Lin, L. Miyagi, A. Addad,  A. Fadel, D. Jacob, F. Béclin, and S. Merkel. Deformation of Polycrystalline MgO Up to 8.3 GPa and 1270 K: Microstructures, Dominant Slip-Systems, and Transition to Grain Boundary Sliding. Front. Earth Sci. 10, 849777 (2022) [doi: 10.3389/feart.2022.849777]

New publication in Geophysical Journal International

Publications, TIMEleSS news

Mapping the edge of subducted slabs in the lower mantle beneath southern AsiaOn March 23rd, 2022, TIMEleSS student Federica Rochira, published a new paper in Geophysical Journal international: Mapping the edge of subducted slabs in the lower mantle beneath southern Asia.

In this work, Federica Rochira, Lina Schumacher, and Christine Thomas from the Westfälische Wilhelms-Universität, Münster, investigate the presence of seismic structures in the Earth’s mantle by searching for seismic signals, and in particular signals from the edges of subducted slabs. They rely on an original approach that uses was that travel off the great circle path direction and are reflected or scattered off structures in the lower mantle and focus on areas of current and past subduction beneath Eurasia by using events from Indonesia and Japan recorded at the broad-band stations in Germany, Morocco and Namibia. Applying seismic array techniques, they measure the direction and traveltime of the out-of-plane arrivals and backtrace them to their location of reflection/scattering.

The results of the work indicate that most of the backtraced reflectors are located beneath southern Asia and are found shallower than 1500 km depth. They correlate well with the edges of prominent high velocity anomalies in tomographic inversions beneath southern Asia, which have been interpreted as remnants of fossil slabs of the subduction of the Tethys Oceans. They also observe few reflectors deeper than 1600 km that are located away from subducting regions and their positions coincide with the eastern edge of the African low velocity anomaly.

These observations suggest that the presence of reflectors in the mid-lower mantle is not exclusively related to current or past subducting regions, but widespread throughout the mantle.

The full details are in the following publication: F. Rochira, L. Schumacher, C. Thomas, Mapping the edge of subducted slabs in the lower mantle beneath southern Asia, Geophysical Journal International, 230, 1239–1252 (2022) [doi: 10.1093/gji/ggac110]

Publication in the European Journal of Mineralogy!

Activities, Publications

Publication in the European Journal of Mineralogy: Deformation of NaCoF3 perovskite and post-perovskite up to 30 GPa and 1013 K: implications for plastic deformation and transformation mechanismA new publication from a TIMEleSS student in the European Journal of Mineralogy : Deformation of NaCoF3 perovskite and post-perovskite up to 30 GPa and 1013 K: implications for plastic deformation and transformation mechanism.

Jeff Gay uses a resistively heated diamond anvil to study the plastic deformation and phase transformation mechanisms in NaCoF3. Under ambient pressure, NaCoF3. crystallizes in the perovskite structure, and later transforms to the post-perovskite. It is hence an excellent analogue to understand the physical properties of bridgmanite, the most abundant mineral on Earth, and dominant component of the Earth’s lower mantle between 660 and 2900 km depth.

These results from a collaboration between the Université de Lille, the University of Utah, University College London, and the PETRA III / DESY synchrotron source were published on 30 Sep 2021 in the European Journal of Mineralogy.

Full reference: J. P. Gay, L. Miyagi, S. Couper, C. Langrand, D. P. Dobson, H.-P. Liermann, S. Merkel, Deformation of NaCoF3 perovskite and post-perovskite up to 30 GPa and 1013 K: implications for plastic deformation and transformation mechanism, European Journal of Mineralogy, 33, 591–603 (2021), abstract [doi: 10.5194/ejm-33-591-2021].

TIMEleSS at the AGU Fall Meeting

Conferences and workshops, TIMEleSS news

AGU Fall Meeting 2020

The Fall Meeting of the American Geophysical Union is on online and everywhere in 2020! The AGU Fall Meeting typically attract over 25 000 registrants from all over the world, in a conference center somewhere in San Francisco, New Orleans, or somewhere else in the United States. This year, the Fall Meeting is fully online and TIMEleSS members are happily joining in for presenting their latest results!

Presentations from the TIMEleSS project include

Enjoy your AGU fall meeting!

TIMEleSS Annual Meeting

Activities, Conferences and workshops, Special Events, TIMEleSS news

TIMEleSS Annual Meeting 2020The 2020 TIMEleSS Annual Meeting was held online on 8-9 September 2020. Members from the Université de Lille (Julien Chantel, Jeffrey Gay, Estelle Ledoux, Sébastien Merkel), the Westfälische Wilhelms-Universität, Münster (Matthias Krug, Federica Rochira, Morvarid Saki, Angelo Pisconti, Christine Thomas), and the Deutsche GeoForschungsZentrum, Potsdam (Sergio Speziale) met for two half-days to discuss current advances and future plans.

The first day was dedicated to progress report by the PhD students. The second day followed by a scientific presentation by our guest Morvarid Saki and discussions on the geophysical implications of the results.

Despite the 2020 conditions, the TIMEleSS project is nicely moving forward. Students are reaching a stage when they fully interact with each other. The PIs can’t wait for next year with results and publications!

 

Seismology training for TIMEleSS members!

Conferences and workshops, Special Events, TIMEleSS news

TIMEleSS February 2020 seismology trainingTIMEleSS members are in Münster!

TIMEleSS PI C. Thomas is hosting a seismology training for TIMEleSS students.

Participants include TIMEleSS students E. Ledoux, J. Gay, F. Rochira, M. Krug, and guests from WWU Münster Mineralogy and Seismology labs.

The training is the opportunity to move on to the next step in the TIMEleSS project: combining Mineral Physics and Seismology observations and try to say something about deep mantle processes!

2nd Deep Earth Mini Symposium in Münster

Activities, Conferences and workshops, Student events, TIMEleSS news

TIMEleSS members at the 2nd Deep Earth Mini Symposium in Münster (18 Nov. 2019)The second Deep Earth Mini Symposium was held at the Institute for Geophysics of the University of Münster on November 18th 2019.

The one day symposium has presentations from local and international speakers who all came to Münster for a day of science and discussions. The workshop was organized by TIMEleSS PI C. Thomas.

TIMEleSS PI S. Merkel gave a presentation entitled Phase transitions in the lowermost mantle : Effect
on microstructures and seismic reflections. TIMEleSS students F. Rochira and M. Krug presented posters on their most recent works.

TIMEleSS Training on Polycrystal Properties Modeling

Conferences and workshops, Special Events, Student events, TIMEleSS news

Training on Polycrystal Properties Modeling, Oct 2019

This weeks, students from the TIMEleSS project and our special guests are in Lille to learn about polycrystalline properties.

The course is focused on calculating elastic properties and seismic wave propagation features in a polycrystal, textured or not. We also spend some time trying to model texture development in a deformed polycrystalline aggregate thanks to VPSC simulations.

The participants from the TIMEleSS project, Jeffrey Gay (Lille), Estelle Ledoux (Lille), Matthias Krug (Münster), Federica Rochira (Münster), are delighted to host our very special guests, Tommaso Mandolini (Lille), Ilya Kupenko (Münster), Angelo Pisconti (Münster), Morvarid Saki (Münster), and Lea Pennacchioni (GFZ) for the week.

All should dream of Euler angles and 3D-rotations by the end of the week!

GeoMünster 2019 “Earth! Past, Present, Future”

Conferences and workshops, Outreach, TIMEleSS news
GeoMünster 2019 "Earth! Past, Present, Future"

TIMEleSS members will be at GeoMünster 2019! GeoMünster 2019 is the Annual Conference of the Deutsche Geologische Gesellschaft – Geologische Vereinigung (DGGV – The German Geological Society) and the Deutsche Mineralogische Gesellschaft (DMG – The German Mineralogical Society). It will be held 22–25 September 2019 at the Münster University, Germany, and will be organized and by the Institutes for Geology and Paleontology, Mineralogy, and Planetology.

TIMEleSS members are organizing a session entitled Minerals in the depths: an experimental approach, with a oral presentation of TIMEleSS student Matthias Krug and a poster from our partner Iliya Kupenko.

See you in Münster in September!

TIMEleSS Annual Meeting

Special Events, TIMEleSS news
TIMEleSS Annual Meeting, Aachen, Germany, July 2019

The TIMEleSS Annual Meeting was held at the Jugendherberge in Aachen, Germany, on 23-24 July 2019. Members from the Université de Lille (Julien Chantel, Jeffrey Gay, Estelle Ledoux, Sébastien Merkel), the Westfälische Wilhelms-Universität, Münster (Matthias Krug, Federica Rochira, Morvarid Saki, Christine Thomas), and the Deutsche GeoForschungsZentrum, Potsdam (Sergio Speziale) met for two days to discuss current advances and future plans.

The first day was dedicated to progress report by the PhD students followed by a scientific presentation by our guest Morvarid Saki. Projects members discussed potential interactions and plans for the next year during the second day.

The meeting a was great opportunity to highlight the current achievements of the project and to focus the work that remains. We now have lot’s of projects and results to look forward to. See you next year for the next meeting and further results!

Estelle Ledoux presents her work at the Colloque de la Sfµ 2019

TIMEleSS news
Colloque de la Sfµ 2019

The Colloque de la Sfµ is the meeting of the French microscopy society. It is held annually and mostly focuses on electron microscopy techniques.

Estelle Ledoux, PhD student partially financed by TIMEleSS, presented her results on EBSD analyzes of plastically deformed polycrystalline MgO. The work is a result of a collaboration between the group at the University of Lille and that of L. Miyagi at the University of Utah.

The results of the work will be useful for the TIMEleSS project for addressing properties of the Earth’s lower mantle.

Frederica Rochira presents her work at EGU

Conferences and workshops, People news, Student events, TIMEleSS news
Frederica Rochira at EGU 2019 in Vienna

Frederica Rochira was at the EGU General Assembly 2019 in Vienna. EGU brings together geoscientists to one meeting covering all disciplines of the Earth, planetary and space sciences. The meeting is held yearly in Vienna, Austria, and, in 2019, it was attended by 16,273 scientists from 113 countries.

Frederica Rochira presented her works entitled Detecting structures in the mid mantle using out-of-plane signals in the multidisciplinary session Dynamics of the mantle in the Earth and planetary bodies: from magma oceans to the present day.

The session, co-organized by TIMEleSS members, included four oral presentations on Thursday as well as 12 PICO presentations early afternoon on Friday. The session was an opportunity for scientists of various fields of geosciences (seismology, geodynamics, mineral physics) to present the results of her works and discuss their implications for understanding the dynamics of mantles, on Earth and other planetary bodies.

Synchrotron beamtime for TIMEleSS

Activities, Experiments, TIMEleSS news
Samples for experiments at PETRA III

The TIMEleSS group is at the PETRA III synchrotron this week-end. Matthias Krug, Estelle Ledoux, Jeff Gay, Julien Chantel, Carmen Sanchez-Valle, Sébastien Merkel, and special guest Anastasiia Zadoia will be spending some time at P02.2…

Two months of sample synthesis, polishing, coating, cutting, and 10 diamond anvil cells loaded.

Nights will be shorts for the next four days. Let’s cross fingers, we need data for our next multigrain diffraction datathon!

PhD student day in Lille

Outreach, Student events, TIMEleSS news
Jeff Gay and Estelle Ledoux at PhD student days at UMET in Lille in 2019

Estelle Ledoux and Jeff Gay presented they current work at the PhD student days for the UMET lab in Lille. The symposium is organized yearly in January.

This one-day meeting is an opportunity to discover the work of current PhD students and the evolution of research in the lab. It is an opportunity for exchanges between students and researchers, exchange ideas, and build strong future collaborations.

The full program of the symposium can be found online in the following document.

Deep Earth Mini Symposium at WWU Münster

Special Events, Student events, TIMEleSS news
Federica Rochira and Matthias Krug at the Deep Earth Mini Symposium in Münster in December 2018

Federica Rochira and Matthias Krug presented posters at the Deep Earth Mini Symposium in Münster. The symposium was organized by TIMEleSS PI Tine Thomas.

This one-day meeting attracted an international and interdisciplinary group of deep Earth scientists, PhDs and Master students, with keynote talks given by Jennifer Jackson (Caltech), Jeroen Ritsema (University of Michigam) and Sebastian Rost (University of Leeds), and a poster session with wine and cheese.

The full program of the symposium can be found online in the following document.

Jeffrey Gay joins the TIMEleSS project

People news, Student events, TIMEleSS news

Jeffrey GayJeffrey Gay is a PhD student in the Earth and Planetary Materials group at the Université de Lille since October 2018.

He received a Bachelor degree in Geology from the Montana State University and a Master degree in Geophysics from the University of Utah in the United States. He is interested in deep Earth materials interactions, extreme conditions experiments, and the deformation properties of minerals. In his free time, he can be found snowboarding, climbing, and cycling. In the past, Jeffrey taught mineralogy and structural geology as a teaching at the University of Utah.

His PhD project is funded by the TIMEleSS project. His role within TIMEleSS will concern phase transitions in mantle minerals.