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Origine de la Terre et des planètes


Our group is interested in deciphering the processes that have shaped planet Earth starting from the inception of the Solar System. First, our research interests include the early evolution and differentiation of the Earth, including large singular events such as the formation of the core or the oxygenation of the atmosphere, early silicate differentiation possibly linked to a magma ocean or the long term evolution of mantle convection that is responsible for producing distinct geochemical reservoirs. Second, our group also focuses on the build up of planetary bodies such as Mars, smaller planets or even the Moon.

Our tools are based on isotope systems and include (i) geochronometers, (ii) stable isotope system that are sensitive to metal silicate separation, volatilization processes or even melting processes (iii) nucleosynthetic anomalies that can be used to characterize the origin and processing of planetary materials in the early Solar Nebula.

Our activities have also extended to other applications of isotope tools to study archeometry, environmental geochemistry of specific pollutants, and nuclear forensics.





Principal research interests: Earth and planetary sciences. Radiogenic isotope geochemistry and geochronology. Cosmochemistry. Planetology. Meteoritics. Igneous geochemistry. Terrestrial and planetary mantle-crust evolution. Mantle dynamics. Crustal growth. Core formation. Early Earth. The terrestrial magma ocean. The Great Oxydation Event. Archeometry. Archeology. Geoarcheology. Anthropology.


Bernard BOURDON (DR)

I would like to understand how planets formed starting from minute dust to larger bodies with several thousands kilometer radius. On the way to their accretion, planets acquire chemical and isotope characteristics that may reveal their history. The focus of my research is to develop novel isotope tools to understand the make up of planetary bodies and to build quantitative models that match our observations.

A second aspect of my research is environmental isotope geochemistry. We develop of isotope tracers for society-driven applications. For example, we are interested in using new isotope metal tracers to understand how the contamination of these metals can be traced and how remediation methods could be designed.



I model mass-dependent isotope fractionation employing ab initio calculations of energy variations due to isotope substitutions. The calculations are based on the density functional theory, which allows for the exploration a vast space of thermodynamical and thermochemical conditions; they focus on the determination of the vibrational spectrum. I work on the isotope signatures of large-scale planetary processes. For example I determined the influence of hydration on the S isotope signature of the Mg-sulfates at the surface of Mars [Stability and spectroscopy of Mg sulfate minerals. Role of hydration on sulfur isotope partitioning, Ema Bobocioiu and Razvan Caracas, American Mineralogist, 99 (7), 1216-1220 (2014)].

Then I worked on the Earth’s core formation: I computed the influence of light elements on the fractionation of Fe isotopes. Comparisons with today values of the Earth’s mantle suggested that H and C yield erroneous Fe isotope fractionation and as such cannot be major light elements of the core [Pressure-dependent isotopic composition of iron alloys, A. Shahar, E.A. Schauble, R. Caracas, A.E. Gleason, M.M. Reagan, Y. Xiao, J. Shu, W. Mao, Science, 352, 580-582 (2016)].

Today my research is centered on the Giant Impact and the Moon formation; I use predictions of isotope fractionation between liquids and vapors during the condensation of the protolunar disk to bring further constraints on the thermodynamics of the Moon formation.


Caroline FITOUSSI (CR)

My research aims at understanding the formation of planets such as the Earth, Mars and the Moon starting from a protoplanetary disk. For this purpose, we develop new analytical tools to identify nucleosynthetic anomalies, isotope fractionation associated with the main physical processes leading to the construction of planets. We work with natural samples (meteorites, lunar or terrestrial samples) as probe for the processes that took place during planetary accretion (volatile element depletion, mixing processes, thermal processing, impacts) and differentiation (core formation). An additional topic of my research concerns the development of isotope tracers for constraining the provenance of nuclear materials and constraining the transformation of these materials during extraction and industrial separation steps.

Post Doctorates


Mathieu TOUBOUL (Post doc)

My main research interests are focused on the use of advanced geochemical techniques to better understand the formation of the Solar System, including planetary formation, chemical evolution and internal dynamics, especially of the Earth and Moon. My work was essentiallydirected on applications of 182Hf-182W short-lived isotopic chronometer, in particular for dating the formation of the Moon and for exploring Earth’s differentiation during the Hadean. I am currently developing new high-precision isotope measurement methods by thermal ionization mass spectrometry for other elements with various geochemical behaviors (lithophile vs. siderophile, refractory vs. volatile) to further constrain the evolution of the protoplanetary disk and the accretion of terrestrial planets.