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

Presented by: 
Wenlu Zhu
Monday 11th April 2016 - 13:30 to 14:30
INI Seminar Room 1
Co-authors: Kevin Miller (Stanford University), Laurent Montesi (University of Maryland), Glenn Gaetani (Woods Hole Oceanographic Institution)

Better constraints on rates of melt migration within the partially molten regions of the upper mantle are required to advance our current understanding of various dynamic processes at ocean ridges. In this study, we synthesized texturally equilibrated mono- and polymineralic aggregates containing various amounts of partial melt and characterized the 3-dimensional (3-D) distribution of melt using synchrotron-based x-ray microtomography. With the availability of the high-resolution 3D melt distribution, we developed digital rock physics models to calculate the physical properties of partially molten rocks. We focus on the characteristic change in melt geometry as a function of melt fraction and lithological variation, and how they affect the transport and elastic properties. Our results indicate that 1) the permeability and melt fraction are related by a power-law relation with an exponent of ~2.7 and geometric factor of 57±28 (Miller et al., 2014); 2) the bulk electrica l conductivity also follows a power-law relationship with melt fraction, with the exponent is ~1.3 and the geometric factor 0.66±0.06 (Miller et al., 2015); 3) in a partially molten rock, in general, the fluid pathways differ from, and are more tortuous than the electric current pathways; 4) lithological melt partitioning is observed: the presence of pyroxene causes melt focusing in olivine-rich regions of partially molten harzburgite. We quantified the effect of lithological partitioning on transport properties.
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University of Cambridge Research Councils UK
    Clay Mathematics Institute London Mathematical Society NM Rothschild and Sons