Pamela Speciale, Whitney M. Behr, Greg Hirth, Leif Tokle

We performed deformation and grain growth experiments on natural olivine aggregates with moderate olivine water contents (COH = 600±300 ppm H/Si) at 1000-1200°C and a confining pressure of 1400±100 MPa. Our experiments differ from published grain growth studies in that most were: 1) conducted on natural olivine cores rather than hot-pressed aggregates, and 2) dynamically recrystallized prior to or during grain growth. The active grain boundary migration processes during deformation and dynamic recrystallization affect the kinetics of post-deformation grain growth, as grain boundary migration driven by strain energy density (⍴GBM) may delay the onset of grain growth driven by interfacial energy (γGBM). We compared our post-deformation grain growth rates with data from previously published hydrostatic annealing experiments on synthetic olivine. At geologic timescales, the growth rates are slower than predicted by the existing wet olivine grain growth law.