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Research Topics in the Stable Isotope Geochemistry Team

Thanks to a double approach using laboratory experiments and natural samples, we study the hydrothermal alteration of mafic and ultramafic rocks.  In particular, carbonation reactions are important CO2 sinks that we try to characterize and better constrain with the isotopic tool. Our objects of study are the ophiolites (Oman, ANR LISZT) and the oceanic lithosphere (southwestern Indian ridge, ANR Ridge Factory).

For further information, feel free to contact Isabelle Martinez, Pierre Agrinier.

Collaboration : Mathilde Cannat (Géosciences marines), Arnaud Antkowiak (Sorbonne Université)

The study of meteorites in our team is focused mainly on characterizing the sulfur and oxygen isotopic ratios of the rocks forming planets. These isotopic ratios provide constraints on the astrophysical environment of our early solar system. This research avenue is relatively new in the modern team, re-initiated about a decade ago. 

Up until now, our work allowed describing the unusually reducing formation conditions of enstatite chondrites, via the study of their S isotopic composition. The validation of O-isotope measurements by laser fluorination in our laboratory has led to several national and international collaborations, reflecting the need for meteorites O-isotope characterization

Our team is funded to study the S isotopic compositions of carbonaceous chondrites, in the hope to constrain sulfur photochemistry in the early solar system and in the protoplanetary disk. 

For further information, feel free to contact Jabrane Labidi.

The characterisation of mantle volatile is a long standing subject of our group, with many discoveries over the last 40 years, from the characterisation of mantle, nitrogen, hydrogen, chlorine and sulfur isotope compositions.

Our studies aims to better document volatile heterogeneity, degassing and in-gassing flux of volatiles in the mantle. We study glasses (mid-ocean ridge and ocean-islan basalts, diamonds mantle xenoliths) and some subduction-related (i.e. metamorphic) rocks and altered oceanic crust in relation with key proxies (for example H2O/Ce, C/Nb, Cu/Y-ratios)

Our results have far reaching implications such as providing new proxies to characterise the the amounts of oceanic crust and fluids assimilated during magma emplacements (Cl-isotopes), the origin and timing of volatile delivery to Earth (O-, H-, C-, N-, S-isotopes) or the role of core sequestration (S-isotopes).

New projects which to better address volatile heterogeneity and its relationship with mantle oxygen fugacity.

For further information, feel free to contact Cyril Aubaud, Pierre Cartigny, Jabrane Labidi, Magali Bonifacie.

In this line of research, we seek to understand the mechanisms of native H2 production in the continental domain, in particular intracratonic where numerous emanations have been identified, by coupling the study of natural samples with experimental work to refine our understanding of these reactions, in particular their kinetics. We are also developing a new geochemical tool: the measurement of rare H2 isotopes (clumped isotopes), which should also allow us to characterize the reactions that produce H2 (temperature, origin of the fluid, etc.).

For further information, feel free to contact Isabelle Martinez, Ugo Geymond (phD), Pierre Cartigny et Jabrane Labidi.

Collaboration: Olivier Sissmann, Julia Guelard (IFPEN), Isabelle Moretti (UPPA)

We use stable isotopes of Chlorine (37Cl & 35Cl) to study the physics of ion transport in porous media. This isotope tracer is sensitive to physical processes such as diffusion, filtration, mixing of water masses, … and practically insensitive to geochemical processes where chloride ions are rarely involved.

Our study of oceanic sediment pore fluids shows that chlorides are systematically depleted in 37Cl compared to seawater whatever the tectonic context (oceanic basins, oceanic plateaus, continental margins, oceanic ridge flanks, accretion prisms of subduction zones, alluvial fans, …). This demonstrates the existence of a very general physical process that removes 37Cl from fluids. It could be the ion filtration of fluids by the clays of the sediments as envisaged in the 1980s. It is likely that the consequences of such ion filtration process are also recorded in the fluids of deep aquifers of sedimentary basins. This chlorine isotope-based tracer will reveal the history of the physics of fluid movements.

For further information, feel free to contact Pierre Agrinier, Magali Bonifacie, Gérard Bardoux.

The knowledge of the laws governing the variations of isotopic compositions (also called isotopic fractionations) is the basis of their use to understand the processes we wish to study. Our team regularly contributes to the determination of some of these laws (called isotopic fractionations) still unknown or little known.

For further information, feel free to contact Magali Ader, Magali Bonifacie, Pierre Agrinier, Pierre Cartigny, Cyril Aubaud, Isabelle Martinez, Jabrane Labidi, Giovanni Aloisi, Vincent Busigny.

From the study of ancient sedimenatry rocks, varying mainly from the Archean and Proterozoic ( 3.8 Ga to 600 Ma), we try to reconstruct the chemical evolution of the oceans and the atmosphere, as well as the evolution of living organisms through the history of the Earth . To answer these questions, we couple isotope tools (C, N, S , O, Fe, Δ47 ) often with petrographic and mineralogical obesrvations. The study of Archean paleo-environments is generally conducted in association with our colleagues from the laboratory Géobiosphère Actuelle et Primitive (GAP).

Interpretation of data on ancient rocks can be complex and requires a calibration of our isotope tools by two complementary approaches:

  • study modern analogs to the ancient oceans, such as the Lac Pavin (Massif Central, France) or Dziani Lake (Mayotte).
  • bacterial cultures in the laboratory and analysis of the products obtained under different physico-chemical conditions.

For further information, feel free to contact Vincent Busigny, Magali Ader, Magali Bonifacie, Giovanni Aloisi.

Behaving both as incompatible and volatile elements, carbon, halogens (among them chlorine and bromine), water and sulfur occur in both magmatic liquids and volcanic gases.

Bearing great potential to reconstruct the magma genesis and history, i.e. its origin, differentiation, evolution, degassing including interactions with meteoric and hydrothermal fluids, our group focusses on the study of both carbon and chlorine isotopes, and since 2011 include the analysis of bromine isotopes.

For further information, feel free to contact Magali Bonifacie, Cyril Aubaud and Pierre Agrinier.

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Géochimie des isotopes stables
Géochimie des isotopes stables
Alteration of the oc...