Mantle Structure and Dynamics - Grain-Scale Simulation of Olivine Phase Transition Under Stress

Learn about mantle structure and dynamics through grain-scale simulation research on olivine phase transitions under stress conditions and their implications for mantle discontinuities. Explore how olivine and its polymorphs, as dominant minerals in the upper mantle and transition zone, control mantle discontinuities through phase transitions determined by pressure and temperature. Discover the significant role of mantle dynamic stress levels (100-300 MPa to several GPa) in affecting mineral reaction positions and large-scale mantle structure. Examine the feedback between pressure and stress on olivine phase transitions at grain scale using Open Phase Studio software based on phase field modeling. Understand how order parameters distinguish different phases and describe their evolution through smooth transition functions and diffuse interfaces. Investigate the Forsterite-Wadsleyite phase transition under various stress boundary conditions, including both isotropic and anisotropic scenarios. Analyze simulation results showing how local pressure variations within Wadsleyite grains create depth offsets of approximately 30 km that are seismologically detectable. Study how anisotropic stress conditions cause Wadsleyite phase growth toward maximum compression directions, creating elongated grain shapes while having minimal impact on phase transition boundaries. Gain insights into how deviatoric stress slightly reduces Wadsleyite growth volume at constant pressure, providing crucial understanding for extrapolating grain-scale results to mantle-scale deformation processes.