%AChandler, Brian%ADevoe, Michelle%AKunz, Martin%AWenk, Hans-Rudolf%BJournal Name: Minerals; Journal Volume: 11; Journal Issue: 4 %D2021%I %JJournal Name: Minerals; Journal Volume: 11; Journal Issue: 4 %K %MOSTI ID: 10329117 %PMedium: X %TUsing Multigrain Crystallography to Explore the Microstructural Evolution of the α-Olivine to γ-Ringwoodite Transformation and ε-Mg2SiO4 at High Pressure and Temperature %XThe introduction of multigrain crystallography (MGC) applied in a laser-heated diamond anvil cell (LH-DAC) using synchrotron X-rays has provided a new path to investigate the microstructural evolution of materials at extreme conditions, allowing for simultaneous investigations of phase identification, strain state determination, and orientation relations across phase transitions in a single experiment. Here, we applied this method to a sample of San Carlos olivine beginning at ambient conditions and through the α-olivine → γ-ringwoodite phase transition. At ambient temperatures, by measuring the evolution of individual Bragg reflections, olivine shows profuse angular streaking consistent with the onset of yielding at a measured stress of ~1.5 GPa, considerably lower than previously reported, which may have implications for mantle evolution. Furthermore, γ-ringwoodite phase was found to nucleate as micron to sub-micron grains imbedded with small amounts of a secondary phase at 15 GPa and 1000 °C. Using MGC, we were able to extract and refine individual crystallites of the secondary unknown phase where it was found to have a structure consistent with the ε-phase previously described in chondritic meteorites. %0Journal Article