Maisy Waech

The theory of plate tectonics is a paradigm of Earth science, and it provides a theoretical link among many of Earth’s processes. Serval major aspects of plate tectonics, such as plate boundary formations, explain the existence of volcanoes, fault lines, and the formation of new continental crust. For instance, in order for a new plate boundary to form there must be a localized weakness in Earth’s lithosphere, which would lead to subduction or transform fault formation. There is consensus that a key feature of plate boundaries shear zones is a fine-grained mixture of multiple phases, which are weaker together than when separate. Several models exist to try and explaining this mixing, and previous work has focused on phase mixing of olivine and orthopyroxene in torsion. Unfortunately, these previous experiments cannot distinguish between these mechanisms of mixing. To overcome these ambiguities, I am examining the initiation of phase mixing in a simpler deformation geometry. Samples were created as a layered aggregate of orthopyroxene and San Carlos olivine. This sample was then placed in a high temperature gas medium apparatus and deformed in compression to 50% strain. Investigating the interface at the boundary between opx and olivine layers will help to distinguish between models of mixing, which will help improve our understanding of plate boundary process.