NoLiMit · Non-Linear Bayesian partition-modeling of the Earth's mantle transition zone
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2018-09-01 → 2021-08-31
- EU contribution
- €270,918
- Participants
- 2
- Scheme
- MSCA-IF-GF
Lines connect the coordinator with its partners.
Results in brief
Non-Linear Bayesian partition-modeling of the Earth's mantle transition zone
The objective of NoLimit was to provide new databases, procedures, and models for analyzing and better understanding how the Earth evacuates its internal heat (convection) and how convection acts to recycle geochemical heterogeneities. This is done through analysis of seismic waves that interact with the mantle transition zone, a region of the Earth between 410 and 660 km depth where abrupt increases of seismic wave speeds are related to mineralogical phase transitions. In this context, the analysis faces two challenges that are accounting for the heterogeneous distribution and the multi-scale resolution of seismic data, and integrating experimental data for interpreting seismic observations in terms of petro-physical properties (temperature, pressure, and rock composition). NoLimit has addressed these gaps with two work packages (WP). Each WP has lead to the development of software modules that can be taken separately, or coupled to each other in a forward or inverse approach. The application of these software to massive seismic datasets has first provided estimates for the maximum temperature in the deep mantle, revealed that hot materials do not rise straight to the surface from the core-mantle boundary, and required an imperfectly mixed mantle in terms of chemistry. An inverse statistical framework has then allowed obtaining new models of mantle geochemical heterogeneities. Resulting models suggest that accumulation of oceanic crust (basalt) occurs near cold downwelling limbs of mantle convection, a view which challenges current understanding of the dynamics of geochemical recycling.
Data: CORDIS, © European Union
Project objective
The Earth’s mantle transition zone (TZ) is a complex region exhibiting mineralogical phase changes as revealed by sharp increases of seismic wave-speed near 410 and 660 km depth. The TZ is a key region for understanding how efficient is mantle convection to recycle chemical heterogeneities. Attempts to isolate the effects of temperature and composition on elastic properties have faced several issues. First, due to the imperfect seismic data coverage, the scales of thermal and chemical heterogeneities remain poorly constrained. Second, seismic and mineral-physics data suffer from large uncertainties, and the relation between seismic observables and in situ thermo-chemical parameters remains questionable. To overcome these limitations, this project will use a partitioning (multi-scale) approach to isolate the effects of mantle temperature and composition from comprehensive seismic databases. Using a Bayesian probabilistic framework, the experienced researcher (ER) will simulate the multi-scale physical properties of the TZ, confront the results with high-pressure mineral physics experiments and with predictions from mantle convective mixing models. The interdisciplinary approach of this project relies on using state-of-the-art numerical methods and high performance computing to answer fundamental questions in Earth Sciences. The uniqueness of the approach arises from quantifying in a probabilistic sense how conceptual mantle-mixing models fit seismic data. The skills developed during this project will re-enforce the competitiveness of both institutions to build seismic models, and to study the Earth’s deep interior. The expected researcher outcome is the re-enforcement of his research network; the benefit of a new environment to efficiently prepare articles and professorship applications; and through appropriate training, the capability of developing a research group. Continued international collaboration will be of enduring value for research and student formation.
Original text from CORDIS.
Participants
Links
Data: CORDIS, © European Union