The recrystallized grain size piezometer for quartz: An EBSD‐based calibration

Abstract We have reanalyzed samples previously used for a quartz recrystallized grain size paleopiezometer, using electron backscatter diffraction (EBSD). Recrystallized and relict grains are separated using their grain orientation spread, which acts as a measure of intragranular lattice distortion and a proxy for dislocation density. For EBSD maps made with a 1 μm step size, the piezometer relationship is D  = 10 3.91 ± 0.41  ∙  σ −1.41 ± 0.21 (for root‐mean‐square mean diameter values). We also present a “sliding resolution” piezometer relationship, D  = 10 4.22 ± 0.51  ∙  σ −1.59 ± 0.26 , that combines 1 μm step size data at coarser grain sizes with 200 nm step size data at finer grain sizes. The sliding resolution piezometer more accurately estimates stress in fine‐grained (<10 μm) samples. The two calibrations give results within 10% of each other for recrystallized grain sizes between 10 μm and 100 μm. Both piezometers match the original light optical microscopy quartz piezometer within error.