CREEP will be structured around 4 cross-disciplinary scientific work packages (WPs) that address the fundamental question of how complex rheologies influence the dynamics of both the shallow and the deep Earth and industrial applications.


WP1. Experimental characterization of complex rheologies

D. Mainprice (CNRS-GM) & C. Spiers (UU)

This WP groups 5 projects centred on the experimental characterization of rheology in the laboratory. These projects address key points for advancing on major geodynamical questions with significant societal impact.

ESR1@CNRS-GM will focus on a key point for understanding the development of plate tectonics on Earth: the mechanical behaviour of the shallow lithospheric mantle, which is highest strength layer in a tectonic plate and that has recently been shown to strongly differ from what is predicted based on extrapolation of the existing hightemperature

ESR2@UU will study the role of fault zones properties on fault reactivation, with direct
implications for assessing potential hazards associated with seismicity related to hydrocarbons production and subsurface storage.

ESR3@UU will focus on a fundamental question for hydrocarbon, hydrogen, and compressed air energy storage: the role of coupled solution transfer and frictional/brittle processes in controlling the rheology, transport properties and containment capacity of rocksalt.

ESR4@UDUR will work on the rheology of active faults, an essential knowledge to perfect our capacity to protect the society from fault-related hazards.

ESR10@UCL will study the rheology and fluid transport properties of granular aggregates, with applications to both faults dynamics and fossil fuels exploration.

ESR5@JGU&Schott/CNRS-GM belongs to WP1&3 as it associates high temperature-high pressure experiments and numerical modelling to study the rheology of glass under extreme conditions, opening the way to new industrial applications. All projects have in common the use of experimental deformation techniques, like deformation rigs and acoustic measurements, to measure flow laws and characterize the active deformation mechanisms, allowing for strong collaborations within the WP. The variety of
subjects will ensure that the ESRs are exposed to a large spectrum of applications of experimental rheology.

WP2. Laboratory modelling of complex rheologies

F. Funiciello (UniRoma3) & A. Davaille (CNRS-FAST)

The 3 projects that compose this WP have in common the use of physical models and analog materials to study the effects of the complex rheology of Earth materials on the planet dynamics. For instance, the most dramatic seismic hazards (mega-earthquakes and tsunamis) are produced in subduction zones.

ESR6@Uniroma3 will address the fundamental question of the role of the subduction interface on the earthquake cycle by associating a statistical analysis of data on natural convergent margins to scaled laboratory experiments using a broad range of materials
with different rheologies.

ESR7@CNRS-FAST will use linear and weakly nonlinear stability analysis to investigate theoretically the origin and morphology of convective instabilities in colloidal dispersions, based on experiments and on the extensive rheometrical database built up at FAST since 2010. Recent experiments at CNRS-FAST have shown that layers of aqueous hard-sphere
colloidal dispersions heated from below and dried from above reproduce key features of Earth-like plate tectonics. The origin of this remarkable behaviour is the strong variability of the rheology of colloidal dispersions as a function of the concentration of the dispersed phase.

ESR8@CNRS-FAST will investigate the conditions responsible for the wide range of responses to mantle plume impacts (volcanic plateaus, single volcanoes, triple-junction rifting, and coronae) by means of laboratory experiments using polymer gels and colloids, whose rheologies combine viscous, elastic and plastic aspects. In these experiments, flow fields will be characterized by 3D in situ measurements of the temperature and velocity fields. Regime diagrams and scaling laws derived from the experiments will allow the results to be applied to planetary dynamics.


WP3. Numerical modelling of complex rheologies

B. Kaus (JGU) & P. Tackley (ETH)

This WP reunites 5 numerical modelling projects. Three of these projects analyze the role of history-dependent rheologies on plate tectonics and mantle convection.

ESR9@CNRS-GM will study the role of the anisotropy of physical properties due to preferred orientation of olivine crystals in the lithospheric mantle on strain localization
and reactivation of ancient plate boundaries during plate tectonics using a 3-D multiscale approach combining finite-element models of lithosphere-scale deformation with viscoplastic self-consistent simulations of evolving anisotropic physical properties.

ESR15@ETH will investigate numerically how the evolution of the microstructure (grain size and orientation) in response to deformation and annealing influences mantle dynamics using 3-D spherical convection models with self-consistent plate tectonics.

ESR16@ETH will analyze the rheological controls of the spatiotemporal variability of seismicity along convergent, divergent and transform plate boundaries.

ESR12@JGU will work on a shorter time and smaller spatial scale, focusing on the interactions between fluids and deformation in geothermal reservoirs. She/he will develop a new massively parallel 3D code for simulating hydrofracturing in poro-viscoelastoplastic rocks and its influence on the local state of stress and the effective rheology of the reservoir.

ESR5@JGU&Schott/CNRS-GM will use numerical modelling to characterize the rheology of glass under extreme conditions.

WP4. Seismological investigations of deformation and rheology

C. Thomas (WWU) & J.M. Kendall (UBRIS)

The 3 projects that compose this WP have in common the use of seismic anisotropy to indirectly study the deformation and the rheology in the Earth.

ESR13@UBRIS/Rockfield will associate seismic imaging and multiscale deformation models to unravel the deformation of salt structures in sedimentary basins, with major
implications to the fossil energy production, as these structures are major traps for oil and gas.

ESR14@UBRIS will use seismic anisotropy measurements to analyse fracture compliance.

ESR11@WWU will work at a much larger spatial scale, using array techniques to study reflections and seismic anisotropy coupled to mineral physics and geodynamical models to constrain the rheology and convective flow pattern at the base of the mantle, in the D” layer.



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