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Deformation of Core and Lower-Mantle Materials
S. Merkel, P. Cordier
Earth hosts large-scale dynamical processes such as mantle or core convection. This chapter focuses on dislocation-related plasticity. It first describes the experimental and numerical methods used for the study of plastic behavior of deep earth phases. The chapter then focuses on the known properties of phases relevant for the lower mantle, D layer, and the inner core. Dominant deformation mechanisms can change with composition, impurities, water content, and external parameters such as pressure, temperature, or strain rate. In the deep Earth, pressure is an agent for phase transformations, producing denser crystal structures with different mechanical properties. Transmission electron microscopy (TEM) is the method of choice for characterizing individual deformation mechanisms such as dislocation types and microstructures. The Peierls-Nabarro (PN) model is a simplification, based on a continuous description of the dislocation that allows for direct atomistic calculations.
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