Temperature and pressure dependence on slip systems in MgO: Insights from large-strain deformation experiments using the rotational diamond anvil cell

MgO is the end-member of the primary constituents of the lower mantle, and identifying its crystal preferred orientation (CPO) developments or slip systems is key to understanding seismic observations and the dynamics of the lower mantle. To investigate the temperature dependence on CPO developments in MgO under high-pressure conditions corresponding to the lower mantle, we conducted large-strain deformation experiments using the rotational diamond anvil cell (rDAC) combined with synchrotron X-rays, achieving pressures up to 80 GPa and temperatures up to 973 K. Our results revealed that the CPO developments in MgO under large-strain deformation are temperature-dependent even at relatively low temperatures. The crystal plane parallel to the shear plane changed from the {110} plane to the {100} plane with increasing temperature and pressure. Based on our experimental results, we constructed a temperature-pressure map that shows the CPO variation of MgO. The temperature-pressure map obtained in this study provides essential foundational information for advancing our understanding of rheology in the lower mantle. • Large-strain deformation experiments on MgO were conducted using rDAC. • Temperature-pressure map of slip system in MgO was constructed. • Slip plane transitions in MgO show negative temperature dependence at high pressures.