Geosystem dynamics, resources and environmental impacts
Animators of the theme : Julie Albaric and Pierre Trap
1. General presentation of the theme - General problem
The group’s work focuses on the dynamics of geosystems, physico-chemical exchanges, deformations and mineralogical transformations occurring in these environments and at their interfaces. They are based on a common theme, fluid-rock interactions, and contribute to a multi-scale dynamic vision: from the understanding of the mechanisms operating at the scale of the mineral to that of the reservoir, from the study of the circulation of fluids at depth and their impact on crustal deformation from rapid phenomena (seconds, days or years) to slow phenomena (Ka, Ma). Les problématiques de recherche du groupe visent à répondre aux enjeux environnementaux actuels et futurs, notamment au travers de l’étude des géoressources, pour en assurer le suivi et contribuer à leur gestion durable et résiliente. GEODE est fortement impliqué dans la formation par la recherche, en association avec le département de Géosciences, dans le cadre de la Licence et du Master de Géologie, et du Cursus Master en Ingénierie. In addition, the training mode of the Master 3G by apprenticeship allows to maintain a close collaboration with companies, favouring a partnership research and development activity. The Master 3G also belongs to the TRANSBIO Graduate School.
2. Structuring and 5-year scientific project
The GEODE theme is structured along two main research axes, corresponding to the group’s scientific anchorage and dealing with fluid-rock interactions in the Critical Zone and within the lithosphere (Critical Zone Dynamics and Lithospheric Dynamics). A third, transversal axis aims to better understand the couplings and transfers between the very shallow and deep envelopes of the Earth. This project mobilises the strengths and specific skills of all the members of the group in order to respond to environmental issues related to natural resources (water, gas, metals) and the impacts associated with their exploitation (contamination of groundwater, induced seismicity, etc.). This research work is part of the France 2030 Decarbonated energy production, Decarbonation and hydrogen and Sustainable critical metals themes as well as the PEPRs Subsoil, OneWater and FairCarbon.
3. Approaches: tools and methods
The GEODE group relies on a strong competence in field analysis and metrology from centimetric to multi-kilometric scales, with a particular effort to jointly assess the physical and chemical characteristics of the objects studied. Field observations/measurements include structural geology, geophysics (passive seismic, electrical tomography), hydrogeology, petrography, pedology. In the laboratory, the group’s research is mainly based on microscopic observation, petrological, geochemical and petrophysical analysis of rocks (PEA²t), and clay mineralogy. The research also benefits from an experimental approach carried out on natural and analogous samples. A technical unit dedicated to the analysis of the mechanical behaviour of rocks and soils in the presence of fluids is being developed within the PEA²t platform.
The objective is also to strengthen this group with an innovative approach combining modelling (thermodynamics, flow in a fissured environment) and experimental studies. These tools make it possible to quantify the physico-chemical processes induced by fluid-rock interactions and heat and material transfer mechanisms. Finally, GEODE is investing in the development of integrated tools (environmental sensors) and monitoring methods adaptable to extreme environmental conditions (polar and volcanic zones, gravity instabilities, underground environments).
4. Study sites
GEODE’s sites are located in France and abroad: Jura, Alps, Auvergne, French Guiana, Massif Central, Montagne Noire, Vosges Massif, Black Forest, Brittany coasts and islands, New Caledonia, USA (Gulf of California, Colorado), Arctic, Africa (Cameroon, Senegal, Tanzania), Japan, Russia (Kola).
The fundamental research developed in the two areas is broken down into a cross-cutting area that aims to better quantify the resources (water, metals and minerals, decarbonised energy) and uses of the subsoil in the energy transition.
This axis is dedicated to the study of physico-chemical exchanges at the hydrosphere - biosphere - atmosphere interfaces. The associated research activities and projects focus on current and ancient soils and hydrosystems, and on the measurement of the anthropogenic pressures they are subject to over time.
The deformation of rocks, classically treated from a mechanical and physical point of view (e.g. stresses, frictions), is strongly influenced by chemical processes (fluid-rock interactions, mineralogical reactions and matter transfers) that play a fundamental role in crustal and lithospheric dynamics. In this axis 2, the GEODE group aims to quantify and model the fundamental parameters and processes controlling fluid-rock interactions from the nanometre to the centimetre scale.
