Metals and Energy for a low carbon society

– Hydrogen: Our knowledge of hydrogen (H2) natural sources, fluxes and stocks in the crust is so limited that it is not yet possible to seriously consider exploitation of this potential energy resource. Hydrogen natural systems represent a new field for research and little is known about hydrogen generation, migration, consumption, and potential accumulation. Hydrogen mobility in the crust is so poorly constrained that even fundamental properties of the molecule such as solubility in deep geological fluids at elevated T and P or adsorption at the mineral-water-gas interfaces are unknown. The objectives of our research projects dedicated to natural H2 are to improve our understanding of the geochemical behavior of hydrogen in the deep geological environments in order to develop new exploration methods. It is based on 1) experimental laboratory studies (kinetics of H2 production by hydrothermal alteration of Fe2+-bearing minerals, H2 solubility in brines, and H2 adsorption by clay minerals), 2) numerical simulations of H2 reactive transport in porous media, and 3) field exploration (quantification of H2 fluxes in the Alps). The strength of this project is to combine experimental, modeling and field approaches to provide an integrated source-to-sink view of hydrogen cycle in the crust and a new exploration methods for hydrogen targeting and resource assessment.

– Magnetite: As already outlined in Axis 2, magnetite (Fe3O4) will be the focus of various studies in the next five years in our group.

(1) The kinetics of magnetite formation under hydrothermal conditions from Fe2+-bearing precursors will be extended to temperatures below 200°C for its relevance to natural H2 production. This research will be partly carried out in collaboration with HYMAG’IN for its implication for the recycling of steel-industry wastes (2) The magnetite phase relationships in low and very-low grade metamorphism will be studied to assess growth conditions and rates in a variety of environments (serpentinites, metabasalts, etc…). (3) The need for better constraining magnetite phase relationships in metamorphic rocks is motivated by the development, in our group, of a new method of U-Th/He dating method using magnetite (and spinel) with closure temperatures of 200°C. In collaboration with the DIMENC (Direction de l’Industrie des Mines de Nouvelle Calédonie), this dating method will be used to constrain the timing of the New-Caledonian ophiolite emplacement and associated serpentinisation (see paragraph below).

– Raw material energy nexus: A close collaboration with our colleagues of economic sciences (Gaël Giraud: Ecole Nationale des Ponts et Chaussées (ENPC)/LISIS, AFD, Energy and Prosperity Chair and Ecole d’économie de Paris (PSE); Mouez Fodha: Université Paris 1 Panthéon-Sorbonne; Sandrine Mathy: Laboratoire GAEL, UGA) was necessary to model the link between mineral resources and energy. Three PhD are presently co-supervised by economists and O. Vidal. We are now building collaborations with physicist (Paris Saclay, CEA) and colleagues from INRIA and VERIMAG (laboratory of applied mathematics and informatic, UGA) to improve the dynamical modelling aspects.

– Metallogeny in the Alps: Within the framework of the Referentiel Geologique de la France (RGF program) program, we will reassess the genetic conditions that lead to the formation of important Pb-Ag deposits and intriguing Ni-Co mineralizations. Structural geology, geochronology, fluid inclusions study, and detailed mineralogical investigation will be coupled to provide an in depth understanding of the mineralizing process at play before and during Alpine orogeny.

Contacts:
– O. Vidal
– L. Truche
– F. Brunet
– B. Malvoisin
– S. Schwartz
– E. Janots