During periods of climate changes, ice sheet shrinking is controlled by the collapse of vulnerable ice shelves at the tip of fast-flowing ice streams. Ice stream collapse has not yet been observed and we therefore lack solid historical data and models to predict accurately their consequences, thus limiting our ability to include such events in sea level projections. In this project, we aim to combine for the first time palaeoglaciological data acquired from former ice stream beds of the Laurentide Ice Sheet with a new experimental setup we developed in our lab to investigate processes of collapse. We here address a hot topic to investigate the ice dynamics/landforms linkage to establish a process-based spatial and temporal model of ice sheet collapse. The project integrates three complementary approaches: (WP1) detailed regional-scale mapping of the geomorphological record left by short-lived ice streams, (WP2) analyses of key lithological, stratigraphical and deformational characteristics of the soft-bed of ice streams and (WP3) physical modelling of unstable glacial systems. In this project, we first aim to reconstruct the origin, timing and processes of past ice stream collapse along the Laurentide Ice Sheet. The combination of experimental and palaeoglaciological data will also contribute to establish new semi-empirical laws that will relate soft-bed changes (erosion, sedimentation, deformation), development of subglacial drainage systems and their efficiencies, ice flow velocities, meltwater production rates and porewater pressure. The numerical modeling community will then be able to implement these new parametrization laws to include ice stream collapse in their ice sheet models.

Icy satellites of Jupiter and Saturn are the only extra-terrestrial planetary bodies where the presence of liquid water has been discovered in a form of subsurface oceans. Subsurface oceans are nowadays the most appealing astrobiological targets and became the focus of diverse interdisciplinary research as well as of upcoming space missions. While a variety of volatile compounds (CO2, CH4, N2, NH3, CH3OH, etc) are expected to be present in significant amount in the oceans of icy satellites of Saturn and Jupiter, they should be stable in the form of gas clathrate hydrates at relevant high-pressure and from low- to temperate-temperature conditions. Clathrate formation and destabilization govern the volatile reservoir and chemical exchange in the interior, and have a major impact on the ocean composition, evolution and astrobiological potential. Despite being the main reservoir of volatiles in large ocean worlds, our knowledge on stability and properties of chemically relevant clathrate hydrates at relevant thermodynamic conditions is very limited. To address the mineralogy, evolution and astrobiological potential of extra-terrestrial oceans and to provide data critical for preparing the future space missions, the current proposal aims exploring multicomponent clathrate hydrates in a wide range of pressures, temperatures and compositions by using in situ single-crystal X-Ray diffraction and Raman spectroscopy at high pressures and low to ambient temperatures.

The moons and dwarf planets witnessed the early stages of formation of the outer Solar system. Classical silicate-iron sulfide mixture densities are inconsistent with low densities inferred for the rocky core (2400-2500 kg/m3) of Titan, Enceladus, Dione, and Ceres. We recently proposed that compositions including the overlooked, abundant carbon component provide a viable model for the low densities of refractory cores. Models point to fractions of C-rich organic matter up to 25 wt% (~40% in volume) in the refractory cores, resulting in close to Solar C/Si and C/O ratios. Forming small carbon-rich planets is a so-far unexplored scenario. Metamorphic and thermal evolution of a C-rich core differs from that of a silicate-sulfide core. It can release C-rich fluids to outer icy layers, and may fuel prebiotic activity, a crucial step to the origin of life if dwarf planets like Ceres accreted to Earth as a late veneer. With this major carbon-rich component, the present structure of large outer Solar system objects is tied to 1) composition through the C/Si (the carbonaceous matter to silicate-sulfide ratio in the core) and C/O ratios (with oxygen from the silicate and ice fraction in the planetary body), and 2) density increase associated with reactions occurring at increasing temperature in carbonaceous matter and silicates in the 600-1200 K range. We propose a coupled experimental and geodynamic approach to explore the density and reactions of carbon and silicate-sulfide, and the plausible compositional range and thermal evolution of these carbon-rich bodies. The models will be used to propose observations to test them and define the conditions of formation of dwarf planets and moons in the solar nebula, such as their position with respect to the so-called "snow" and "soot" lines.

The structure and dynamics of Earth's mantle and core are determined by the heat flux across the core-mantle boundary (CMB). The CMB heat flux pattern affects the morphologies of core convection and the generated geomagnetic field. Paleo- and archeomagnetic field models provide valuable insights into persistent features that may be controlled by the lower mantle heterogeneity, including the South Atlantic Anomaly (SAA) – a region of particularly weak intensity at Earth’s surface, where energetic particles penetrate the atmosphere thus posing severe problems to positioning systems and spacecraft electronics. Our goal is to identify persistent geomagnetic field features that will then be used to evaluate how Earth-like are dynamo models with heterogeneous outer boundary heat flux. To recover geodynamo features that are controlled by lower mantle heterogeneity, a precise knowledge of the CMB heat flux pattern is needed. Compositional and mineralogical contributions to the lateral variability of the seismic velocity in the D’’ layer distort inferences of the CMB heat flux from seismic tomography. We will infer thermal-seismic relations from mantle convection simulations in order to isolate the thermal part of the seismic anomalies. Our objective is to apply this relation to mantle tomography models in order to properly model the CMB heat flux. The most fundamental property of dynamo models is their regime, i.e. whether the generated field is dipole-dominated non-reversing or multipolar reversing. This proposal aims at establishing the necessary ingredients for each dynamo regime, taking into account the CMB heat flux pattern and amplitude of heterogeneity. Using adequate CMB heat flux models and testing the consistency of the dynamo models output with criteria derived from paleomagnetic field models, our goal is to evaluate the Earth-likeness of a large set of dynamo models with heterogeneous outer boundary heat flux.

The Plate Tectonics theory fails to explain the occurrence of deformation and earthquakes in Stable Continental Regions (SCR, areas far from plate boundaries, over half of continental surfaces). Recent studies show that climate-related processes such as erosion and hydrology can strongly influence faults and earthquakes on short time scales (1–100 yr), yet few studies address the role of long-term climate and landscape erosion on deformation and seismicity in Stable Continental Regions. The objective of the “EroSeis” project is to test the original hypothesis that “Present-day deformation, seismicity and seismic hazard in Stable Continental Regions are strongly influenced by long-term erosion rates”. The project will rely on very recent developments to quantify local and regional erosion, deformation and seismicity rates, and integrate them in numerical models, in order to test under which conditions erosion can serve as a catalyst to seismicity.