Evolution of Melt Distribution During Deformation of Partially Molten Mantle Rocks: Implications for Geodynamical Processes

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9815039 Kohlstedt Connectivity and grain-scale distribution of melt in a partially molten rock control permeability, rheology, electrical conductivity, seismic velocitie and seismic attenuation. This research is designed to quantify the evolution of melt topology during deformation of partially molten mantle rocks. To date, most studies of melt distribution have concentrated on samples exposed only to a hydrostatic conditions; few have characterized melt topology in partially molten materials subjected to a non-hydrostatic state of stress. The PI's recent experiments demonstrate that deformation has a dramatic effect on melt geometry and, consequently, on physical properties. To apply observations concerning the influence of deformation on melt connectivity and distribution obtained under laboratory conditions to processes such as convection and melt migration occurring at mantle length and time scales, the mechanism by which melt redistribution takes place must be understood. To address this issue, the PI has designed a series of experiments to quantify the physical parameters that govern the occurrence and nature of a deformation-induced melt distribution. An important goal of these experiments is to determine quantitative relationships between deformation conditions, such as stress and strain rate, and melt distribution. These results are essential for developing a theoretical framework that will permit reliable extrapolation of laboratory results to mantle environment and for utilizing experimental results to develop models of the dynamic behavior of Earth's interior.