Phase Change Related Mechanical Instabilities During Two-Phase Flow in the Mantle.

Abstract:

Migration and storage of partial melt in the Earth's mantle are controlled by an interplay of compaction, gravity, surface tension, and phase change (e.g. melting and freezing). At temperatures close to the solidus, the volume fraction of the melt is typically small. The mobility of such small volume fractions of melt depend on the permeability and melt viscosity. In addition, surface tension at grain-grain-melt triple junctions can influence the efficiency of melt extraction from the source region. Finally, deformation of the matrix creates melt-rich bands, rendering the mobility anisotropic. Dissolution-precipitation controlled diffusive mass transfer, however, can homogenize such melt segregation in small length scales.

In this work, we present results from linear stability analyses and finite elements model outlining the influence of these competing processes on the migration of partial melt in the Earth's mantle. We also present results outlining the efficiency of our massively parallel finite elements solver for the two phase flow and comparison between different preconditioners.