Paper accepted to Tektonika
Wang et al., 2024: Viscous Anisotropy of Olivine Textures in Shear and Subduction Models
European Geosciences Union General Assembly 2023
Vienna, Austria (2023. April 24-28)
On Tuesday, the ANisotropy from Crust to Core session took place, where Yijun presented her poster on the Effect of olivine anisotropic viscosity in advancing and retreating subduction settings. The poster received good attention, and we had inspiring conversations about the study.
Ada Lovelace conference
Héviz, Hungary (2022.08.28-09.02)
The Ada Lovelace conference is the biennial meeting for geodynamicists. Over 150 scientist gathered in person in Hungary, and many more online to share their work with the community. We presented two posters about ANIMA; Yijun showed her work on analyzing the differences between texture evolution models, while Ági presented a poster about the progresses we made on implementing anisotropic viscosity calculations into the ASPECT code.
RhEIA MEETING, Paris (2022.10.20-21)
After the very inspiring Ada Lovelace conference, Ági also travelled to Paris to present the ANIMA project at the RhEIA - Rheology of Earth's interior across scales - workshop. Here we reached out to the Rheology community, and had great discussions about the possibilities and excitement of the project.
ASPECT HACKATHON 2022 in CODY, WYOMING
ASPECT development workshop organised by CIG
In May, CIG organised its yearly development event for ASPECT, where the main developers gather together with some users, to work on their projects together. This year, ANIMA was well represented, and provided one of the focal point of the Hack. Both PI, Ágnes Király and Ph.D. student Yijun Wang was there to work on the integration of anisotropic viscosity calculations into ASPECT. We received great help from our project partners: Julinae, Rene, and Menno. While we worked hard on our projects, we also made sure to enjoy the surroundings, making even a trip into the Yellowstone National Park. We had a great time! Thanks to the organisers, especially to Lorraine Wang for making this happen, and giving us such a great experience of being part of the ASPECT community.
ASPECT Hackathon log - ANIMA edition:
Anisotropic Viscosity (AV) Using fixed euler angles on compositional fields (from last year)
By Ági Király:
The first step of implementing Olivine LPO (or CPO) related anisotropic viscosity was achieved by describing olivine texture by 3 compositional fields related to the 3 euler angles of the orientation of the olivine texture. Note: this method assumes 1 olivine grain per cell, and does not deal with the evolution of the grain’s orientation. AV is calculated based on the micromechanical model described by Hansen et al. (2016), and calculates the viscosity tensor similarly to the methods described by Kiraly et al. (2020). I also added a post-processor for saving the anisotropic stress tensor, which is the actual stress the model needs for achieving the given strain rate.
Results in a shear box. Arrows show the input velocity field. Red discs represent the strain rate tensor, green disks the isotropic stress tensor, while the white ones the anisotropic stress tensor. The orientation of the olivine grains (shown in the right bottom corner) can be described by (10, 20, 30) euler angles. In this case the anisotropic stress has a significant amount of normal stresses as well as shear stresses primarily on the xz component, but also on the xy component (while the strain rate and the isotropic stress have only the xz and yz components that are non 0).
Anisotropic Viscosity (AV) Using CPO data on particles
By Ági Király:
The next step in the implementation of Olivine CPO related AV is to actually use the CPO data (based on Fraters and Billen, 2021). To do so, we implemented a particle property that calculates the anisotropic stress from the current strain rate and the current texture (CPO) on each particle. Using the equivalent strain rate as amplitude for 5 independent strain rates we calculate 5 more stresses, that are required for building the full rank 4 viscosity tensor. We store these 6 stresses (36 components) on the particles, and interpolate them onto compositional fields. In the material model, we load the compositional fields and use them for the calculation of the viscosity tensor. I am currently running models using this material model in a shear box and compare them to our model in MATLAB (Király et al., 2020).
Next steps: test it in different setups ; Implement AV with diffusion-dislocation /visco-plastic rheologies, where the dislocation creep part acts anisotropically.
Anisotropic Viscosity (AV) using dislocation strain rate
By Yijun Wang:
Continuing with what Agi has done above, we worked on computing the dislocation strain rate in the anisotropic viscosity material model, and use this dislocation strain rate for anisotropic viscosity calculations in this material model, and in the particle property where we compute the anisotropic stress tensor required to achieve the current strain rate. Now that the dislocation creep part is working, we need some tests to see that it is behaving as we expected.
CEED Christmas Symposium and AGU Fall Meeting
D for Dissemination in December
December is a busy month for the ANIMA team members, having multiple seminars and meetings where we can show our work.
Between the 8-10th of December CEED holds its Christmas Symposiums on the cruise between Oslo and Kiel. Both Ági and Yijun give talks during the seminars:
How to win a Researcher Project for Young Talents: The initial phase of ANIMA. - by Ágnes Király From geodynamic modelling of subduction systems to ANIMA. - by Yijun Wang
The next week (12-17th of December) AGU Fall Meeting will happen in New Orleans and on-line. From ANIMA team members there are a number of contributions to look out for:
DI52A-01: Slabs, edges, and gaps (invited) /Á. Király
MR43A-07: On the Implementation and Usability of CPO Evolution in Geodynamic Modelling / M. Fraters & Billen DI15B-0019: The Morphology, Evolution and Seismic Visibility of Partial Melt at the Core-Mantle Boundary: Implications for ULVZs / J. Dannberg et al. MR44A-04: Water Does Not Influence the Plasticity of Olivine at Low Temperatures /L. Hansen et al.
German-Swiss(-Norwegian) Geodynamics workshop
Keynote lecture in Bad Belzig
PI Ági Király was invited to give a keynote presentation at the German-Swiss Geodynamic workshop the end of August in Bad Belzig, Germany. The workshop had a record number of participants, as this was the first in person conference many could experience in 2 years. Ági gave a great lecture about subduction dynamics and slab interactions, based on the paper Király et al., 2021. Photo credit: @EGU_GD
It was a pleasure to participate and meet with the German and Swiss colleagues!
July, 2021
ASPECT HACKATHON
First two weeks of July, online Hackathon
At the starts of July, Project Manager Ágnes Király, together with project partners and ASPECT developers Juliane Dannberg, Rene Gassmoeller, and Menno Fraters, have participated at a two weeks workshop aiming to work on new developments for ASPECT. It was challenge that we all accepted and finally we had an enjoyable 2 weeks long workshop. The part of anisotropy had faced some difficulties, but significant progress has been and continued to be made.