Thermo-mechanical impacts of metamorphic transformations on rock deformation

Density and viscosity variations induced by metamorphic transformations can significantly impact rock strength. However, despite their importance, most models still largely overlook these transformations.

The goal of this presentation is to clarify and quantify the rheological effects of each of these changes. To achieve this, we first introduce numerical methods that incorporate the dynamic effects of transformations in models (e.g., volume and viscosity changes). In a second time, we illustrate separately the effects of (1) density changes and (2) viscosity changes when a rock undergoes transformation under stress. The models presented enable the study of the dynamic evolution of strain, stress, and pressure fields as a new phase forms within an initially homogeneous rock undergoing transformation.

Our results reveal that, in certain cases, changes in stress and pressure fields can be significant. These findings are particularly crucial for understanding the brittle behavior of rocks under high-pressure conditions. It consequently provides valuable insights into intermediate-depth seismicity occurring in subduction zones.