진학프로석·박사 채용 접수 플랫폼

Presentation of the project :

The existence of an atmosphere enriched in H and He around the Earth as it formed has often been proposed. One hypothesis suggests that it could have been captured from the gas present in the proto- planetary disk, before its evaporation. Subsequently, a secondary atmosphere would have been degassed or brought in by a late veneer of chondritic/cometary material. Although this model is regularly evoked using giant planets for comparison, there is no geological proof for its existence, except possibly for the neon in the Earth's mantle. While the model has a flaw (mainly relating to chronology, as the gas from the disk is lost in <6 My while the Earth formed over a period of more than 30My), the solar-type neon
in the Earth's mantle is an argument for the existence of such a captured atmosphere, which partially dissolved into a magma ocean. A second scenario for a primordial H2/He-rich atmosphere is the degassing of a mantle that contained implanted solar wind. The APATE project aims to study the isotopic composition of neon in the Earth's mantle in order to determine if this composition is the same as that of the nebula or the solar wind material. In the project we investigate the degassing processes of magmas experimentally and numerically in order to study the isotopic fractionation that occurs during bubble formation and to determine whether the measured neon isotopic composition can provide an accurate composition for the original mantle. The project also aims to calculate the amount of neon that can be incorporated into a magma ocean by establishing the atmospheric pressure of the captured atmosphere and by studying the dynamics of the magma ocean. We will also explore the hypothesis involving solar wind irradiation. The origin of light solar volatiles will then be explored by the APATE project.

Presentation of the Service / laboratory :

ISTO is a scientific research laboratory under the joint supervision of three institutions: the CNRS, the University of Orléans, and the BRGM. It is located at the Orléans-la Source site (45100), on the CNRS campus.
The laboratory possesses a state-of-the-art analytical suite for noble gas geochemistry: 4 Helix SFTs, 2 Noblesse instruments, and 3 quadrupole mass spectrometers.

Presentation of the missions :

The position will primarily involve using mass spectrometry to study:
- the noble gas isotopic composition of various hotspots, with a particular focus on neon and argon isotopes
- noble gas isotopic fractionation in various settings, including active hydrothermal systems

The work will therefore comprise a laboratory analysis phase, followed by the modeling of results within the relevant geological contexts.

Présentation of the profile :

- Recent PhD in Earth Sciences with a specialization in Geochemistry and Hydrothermalism;
- Knowledge in geochemistry, volcanology, and hydrothermal systems;
- Excellent command of both English and French, written and spoken.

- Previous experience in analyzing data collected from a hydrothermal site
- Proficiency in modeling tools for hydrothermal systems