Modeling dynamic recrystallization of olivine aggregates deformed in simple shear

Experiments by Zhang and Karato [1995] have shown that in simple shear disl ocation creep of olivine at low strains, an asymmetric texture develops wit h a [100] maximum rotated away from the shear direction against the sense o f shear. At large strain where recrystallization is pervasive, the texture pattern is symmetrical, and [100] is parallel to the shear direction. The d eformation texture can be adequately modeled with a viscoplastic self-consi stent polycrystal plasticity theory. This model can be expanded to include recrystallization, treating the process as a balance of boundary migration (growth of relatively underformed grains at the expense of highly deformed grains) and nucleation (strain-free nuclei replacing highly deformed grains ). If nucleation dominates over growth, the model predicts a change from th e asymmetric to the symmetric texture as recrystallization proceeds and sta bilization in the "easy slip" orientation for the dominant (010)[100] slip system. This result is in accordance with the experiments and suggests that the most highly deformed orientation components dominate the recrystalliza tion texture. The empirical model will be useful to simulate more adequatel y the development of anisotropy in the mantle where olivine is largely recr ystallized.