Strain Localization and Bulk Rheology Variation in Partially Molten Rocks: Insight from Analogue Model Experiments of Polyphase Materials. Koziol, Conrad
Results of analogue experiments are analyzed to investigate strain localization and the response of materials with volumes of partial melt between 0-38% to applied pure shear. Partial melt is simulated through lower viscosity inclusions of Vaseline in a homogeneous block of higher viscosity paraffin wax. Samples are deformed at a constant natural strain rate in a pure shear, plane strain deformation rig. Processing of the experiments with Particle Imaging Velocimetry software reveal the development of shear bands, linear regions of concentrated shear strain. Shear bands nucleate on low viscosity inclusions and form networks connecting inclusions at low levels of deformation. Deformation within the analogue model experiments is characterized by the dimensionless shear band length, and is found to decrease as the ratio of stress in the Paraffin wax to the stress in the Vaseline increases. The flow stress of our analogue models decreases non-linearly with increasing volume percentage melt. No substantial decrease in the flow stress was found at melt volumes between 0% and 38% corresponding to the rheologically critical melt percentage (RCMP).
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