Viscous sintering under load and its implications for the development of permeability anisotropy

Anthony Lamur, Fabian B. Wadsworth, Jackie E. Kendrick, Jérémie Vasseur, Yan Lavallée

• Affiliations:  Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität, Munich, Germany 

• Presentation type: Poster

• Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

• Poster Board Number: 220

• Programme No: 3.2.43

• Theme 3 > Session 2

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Abstract

A growing number of field evidence suggests that lavas readily fragment and sinter back together during transport, eruption and or emplacement. In the last decade, advances in the kinetics of viscous sintering have contributed to a better understanding of how fragments may densify into a coherent body under isothermal and non-isothermal conditions, and while the effect of external loading has been theorised, it has not yet been experimentally demonstrated. Here, we use poorly-sintered glass bead cores of 25mm (1:1 aspect ratio). We place the cores in a uniaxial press mounted with a furnace and apply constant loads of 5-100N for 5h at 660^oC. We measure porosity pre- and post-experiment in a helium pycnometer. The permeability of each deformed core is also measured in a gas permeameter at confining pressures of 0.7-2.1 MPa in the axial and radial directions to estimate permeability anisotropy. We show that for the samples held below a transitional  load of 40N, the permeability in both axial and radial directions is the same and that it is predicted by the existing isostatic permeability models. For samples held at higher loads, we observe higher radial permeabilities than axial, an effect magnified by the load magnitude. Thus, our results corroborate the theoretical framework and have implications for how fluids flow in anisotropically permeable sintered lavas.