Torsion of a cylinder of partially molten rock with a spherical inclusion: theory and simulation
Geochemistry, Geophysics, Geosystems
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Alisic, L., Rheberen, S., Rudge, J., Katz, R. F., & Wells, G. (2015). Torsion of a cylinder of partially molten rock with a spherical inclusion: theory and simulation. Geochemistry, Geophysics, Geosystems, 17 143-161. https://doi.org/10.1002/2015GC006061
The processes that are involved in migration and extraction of melt from the mantle are not yet fully understood. Gaining a better understanding of material properties of partially molten rock could help shed light on the behavior of melt on larger scales in the mantle. In this study, we simulate three-dimensional torsional deformation of a partially molten rock that contains a rigid, spherical inclusion. We compare the computed porosity patterns to those found in recent laboratory experiments. The laboratory experiments show emergence of melt-rich bands throughout the rock sample, and pressure shadows around the inclusion. The numerical model displays similar melt- rich bands only for a small bulk-to-shear-viscosity ratio (five or less). The results are consistent with earlier two-dimensional numerical simulations; however, we show that it is easier to form melt-rich bands in three dimensions compared to two. The addition of strain-rate dependence of the viscosity causes a distinct change in the shape of pressure shadows around the inclusion. This change in shape presents an opportunity for experimentalists to identify the strain-rate dependence and therefore the dominant deformation mechanism in torsion experiments with inclusions.
This work was supported by the UK Natural Environment Research Council under grants NE/I023929/1 and NE/I026995/1. Computations were performed on the ARCHER UK National Supercomputing Service (http://www.archer.ac.uk). We thank Chris Richardson for all his support with running the simulations on ARCHER. Katz thanks the Leverhulme Trust for support.
External DOI: https://doi.org/10.1002/2015GC006061
This record's URL: https://www.repository.cam.ac.uk/handle/1810/252672