Abstract
Grain-growth kinetics of (Mg0.85Fe0.15)O ferropericlase was investigated at pressures of 5 and 10 GPa and temperatures of 1673-1873 K using a Kawai-type multi-anvil apparatus. Presintered ferropericlase aggregate with an average grain size of 4.0 μm was used as starting material of grain-growth annealing experiments. The grain-growth kinetics of ferropericlase is described by Gn - G0n = k0 t exp [ - (E* + P V*) / R T ], where G is the average grain size at annealing time t, G0 the initial average grain size, P the pressure, R the gas constant and T is the absolute temperature, with n = 2.6 ± 0.4, log10 k0 = -7.5 ± 1.7 m2.6/s, E* = 262 ± 30 kJ/mol, V* = 4.7 ± 0.7 cm3/mol. Compared at same pressure and temperature, grain-growth rate of ferropericlase is similar to olivine and faster than those of wadsleyite and ringwoodite. The present results show that, at the top of the lower mantle (P = 25 GPa and T = 1773 K) grain size of ferropericlase in single phase system evolves to ∼2 × 10-2 m after significant geological time (10 My) while a previous study predicts that grain size of MgO in two-phase system is as small as ∼8 × 10-6 m at same condition.
Original language | English |
---|---|
Pages (from-to) | 145-152 |
Number of pages | 8 |
Journal | Physics of the Earth and Planetary Interiors |
Volume | 174 |
Issue number | 1-4 |
DOIs | |
Publication status | Published - May 2009 |
Externally published | Yes |
Keywords
- Annealing
- Ferropericlase
- Grain growth
- Grain size
- High-pressure
- Lower mantle
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Geophysics
- Physics and Astronomy (miscellaneous)
- Space and Planetary Science