Grain growth kinetics of majorite and stishovite in MORB

Grain growth rates of majorite and stishovite, in their aggregates with MORB composition, were studied at 18 GPa and temperatures ranging from 1873 to 2223 K. The rates of grain growth were expressed by G(n) - G(0)(n) = k(0)t exp(-H*/RT) where G is the grain size at time t (s), and G(0) is the initial grain size. We determined the grain growth kinetic parameters for majorite, where n = 9.1 +/- 1.3, H-* = 950 +/- 249 kJ/mol, and log k(0) = -32.5 +/- 2.3 m(9.1)/s for the graphite capsule and log k(0) = -31.3 +/- 3.9 m(9.1)/s for the Re capsule. Kinetic parameters for stishovite were determined to be n = 6.6 +/- 0.9, H-* = 599 +/- 226 kJ/mol, and log k(0) = -30.6 +/- 0.9 m(6.6)/s for the graphite capsule and log k(0) = -29.0 +/- 1.1 m(6.6)/s for the Re capsule. (C) 2010 Elsevier B.V. All rights reserved.