Shear response of Fe-bearing MgSiO(3) post-perovskite at lower mantle pressures.

We investigate the shear response of possible slip systems activated in pure and Fe-bearing MgSiO(3) post-perovskite (PPv) through ab initio generalized stacking fault (GSF) energy calculations. Here we show that the [100](001) slip system has the easiest response to plastic shear among ten possible slip systems investigated. Incorporation of Fe(2+) decreases the strength of all slip systems but does not change the plastic anisotropy style. Therefore, pure and Fe-bearing MgSiO(3) PPv should demonstrate similar LPO patterns with a strong signature of the [100](001) slip system. An aggregate with this deformation texture is expected to produce a V(SH) > V(SV) type polarization anisotropy, being consistent with seismological observations.(Communicated by Ikuo KUSHIRO, M.J.A.).