Description du sujet de thèse

Determine the behavior of volatile elements (C, N, H, O, S) during and just after core formation. The innovative aspect of this project is to be able to simulate the complexities of compositions involving metallic and silicate phases under the conditions of formation of the Earth's core. This is the first time that all the volatile elements will be taken into account so that their mutual interactions can be studied. In addition to experimental data, we will develop models of the behaviour of volatile elements as a function of pressure, temperature, oxygen fugacity and the chemical compositions of the silicate and metallic phases. To build these models, we will use the new data derived from this PhD project, in combination with all the pre-existing data from experimental studies, theoretical and numerical modelling, and geochemical and cosmochemical constraints. With this work, we will be able to produce quantitative constraints on the chemical composition of the Earth's core in volatile elements, as well as that of the silicate Earth.
Three objectives are defined in this thesis project:
1- Simultaneous determination of the metal-silicate partition coefficients of (C, H, N, S, O) under deep magma ocean conditions (from 2 to 75 GPa; 2000 - 3500 K; and an oxygen fugacity varying between IW-2 and IW-5).
2- Determination of C, H, N, S and O contents in the Earth's core and in the silicate Earth.
3- Construction of thermodynamic models that will predict meta elemental partitioning.

Contexte de travail

The experimental petrology team comprises some 15 permanent researchers and is equipped with a full range of experimental devices, including controlled-atmosphere furnaces, piston-cylinders, multianvil presses and diamond anvil cells. In addition, the laboratory has various analytical facilities such as an electron microprobe, scanning electron microscope (SEM), laser ablation mass spectrometry (LA-ICP-MS), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy.
The recruited PhD student will work within the LMV's experimental petrology team and will benefit from
- a stimulating work environment in contact with research staff
- professional support with in-house training
- Partial reimbursement of travel expenses (75%)
+ sustainable mobility package of up to €300/year
- A site accessible by public transport (streetcar + bus)
- 44 days vacation / RTT per year

Contraintes et risques

Safety rules must be observed every time the instruments are used.