Physical Properties of Partially Molten Rocks from Microtomography Experiments and Digital Rock Physics

University Of Maryland, College Park, College Park MD

Investigators

Abstract

Melt generated in the interior of the Earth at plate boundaries plays an important role in the transfer of heat and mass and eventually feeds the volcanic activity of our planet. It is important to better constrain how much melt is present at depth and where it is present. Seismic and electromagnetic measurements provide data to constrain melt distribution but how to convert these data into melt fraction estimates remains a subject of contention. This project will analyze three-dimensional images of the distribution of melt in experimentally produced partially molten rocks and simulate several physical properties of these samples. Results from this study will make it possible to link seismic and electromagnetic data with models of melt transport in the interior of the Earth, which ultimately helps understand how plate tectonics works and the link between mantle processes and volcanic activity. This study will use synchrotron microtomography to image partially molten mantle rocks in three-dimensions. The samples will be hydrostatically-annealed aggregates that consist of olivine and orthopyroxene in different proportions, and contain melt fractions of 0.005 to 0.20. Digital rock physics simulations will be performed to obtain permeability, electrical conductivity and elastic moduli of both hydrostatically annealed olivine + orthopyroxene-basaltic melt and sheared partially molten olivine rocks. Variation of melt content with distance in the sample will be analyzed to constrain the bulk viscosity of the sample. This project will quantify the effects of lithological partitioning due to the presence of orthopyroxene on melt distribution and show how deformation affects melt distribution, and induces permeability anisotropy.