Sediment Mobilization: Deformation Mechanics, Fluid Transport, and Implications for Large-Scale Tectonic Processes

This project focuses on the hypothesis that at certain conditions, shallow and deeply buried large, fine-grained sediment bodies behave in a ductile manner with a bulk viscous rheology, and that related to that flow a substantial, yet fundamentally unquantified, amount of heat and fluid transfer between the lithosphere, hydrosphere and atmosphere occurs within the Earths uppermost kilometers. This hypothesis is based upon the assumption that at certain conditions shallow unconsolidated but also deeply buried lithified fine-grained sediments undergo mobilization triggered by excess pore fluid pressure resulting in a weak ductile rheology that enhances vertical material, fluid, and heat exchange. This project aims to test the stated hypothesis with a novel multidisciplinary approach based on three pillars:

• Observation of onshore exposures related to sediment mobilization, such as mud diapirs and mud volcanoes. SW Taiwan is an ideal natural laboratory to observe these geological features.
• Seismic data modelling and interpretation to obtain physical properties such as density, porosity, and fluid pressure within deep sedimentary basins affected by sediment mobilization.
• Numerical modelling, including thermo-mechanical experiments testing experimentally retrieved rheological parameters and developing novel coupled two-phase fluid flow experiments.

The outcome of the proposed research has vast ground-breaking implications beyond its scientific merit: Constraints on mobile shale/mud will improve our understanding of i) the seismogenic potential of overpressured shallow portions of subduction interfaces, ii) the dynamics of tsunamigenic submarine mass flows, and iii) the interplay between local deformation, fluid pathways at depth, and potentially devastating mud extrusions at the surface. The ultimate goal of the project is to obtain a budget of fluid and heat transfer related to sediment mobilization that affects both human life and global climate.