Phase Transitions and Mantle Mixing: Effects of Three-Dimensionality and Temperature-Dependent Viscosity, and Relationship to Observational Constraints

Abstract

In recent years there has been much interest in the question of mantle layering induced by the endothermic phase transition at 670 km depth, and a partially or intermittently layered mantle characterized by accumulation of downwellings in the transition zone and catastrophic avalanches into the lower mantle has been indicated by several numerical studies. Now that this basic pattern has been established, the challenge is to better constrain how the model results relate to convection with the actual Earth, by (1) improving the realism of numerical models, including such effects as three-dimensionality (3-D) and temperature-dependent viscosity, and (2) relating the theoretical results to a wider range of observations. Thus, this talk will focus on these issues.