Deformation of ZrSiO4 -MgO aggregates: Deviatoric stress as a control on deformation mechanisms

Deformation behavior of multiphase aggregates has great significance for materials design and understanding the dynamics of the Earth. Here we studied the deformation of zircon (ZrSiO4)-MgO aggregates and found that the introduction of MgO reduced overall deviatoric stress in the aggregates and thus controlled deformation mechanisms of the zircon phase. Zircon primarily deforms by a dominant {101}(10-1) slip; however, activity of zircon {100}(010) slip increases with the introduction of an increased ratio of MgO into the aggregates, as suggested by the experiments and simulations. We also found both zircon and MgO in the aggregates retained strong deformation texture, which is likely related to the symmetric variants of the dominant slip system of the hard zircon phase. Our results help to clarify the discrepancies in previous studies and understand which phase may dominate the seismic anisotropy in geosciences.