Extended Data Fig. 4: Effect of grain boundary sliding (GBS) on upper mantle dynamics.
From: Grain-size-evolution controls on lithospheric weakening during continental rifting
Colors indicate the percentage of GBS strain rate relative to the total strain rate for the upper mantle: \(\Gamma _{GBS} = \dot \varepsilon _{GBS}/(\dot \varepsilon _{GBS} + \dot \varepsilon _{disl} + \dot \varepsilon _{diff})\). (a) COH = 50 H/106Si. (b) COH = 600 H/106Si. The GBS flow law by Ohuchi et al.39 follows \(\dot \varepsilon _{GBS} = A_{GBS}f_{{{\mathrm{H}_2\mathrm{O}}}}^{r_{GBS}}\frac{{\sigma ^n}}{d}\exp \left( { - \frac{{E_{GBS} + V_{GBS}P}}{{RT}}} \right),\) with AGBS = 10−4.98 MPa−n, nGBS = 3, rGBS = 1.25, EGBS = 423 kJ, and VGBS = 17.6 cm3/mol.
