Pressure dependence of olivine grain growth at upper mantle conditions

Filippe Ferreira; Marcel Thielmann; Robert Farla; Sanae Koizumi; Katharina Tinka Marquardt

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arXiv · 2504.08425

Pressure dependence of olivine grain growth at upper mantle conditions

Filippe Ferreira·Marcel Thielmann·Robert Farla·Sanae Koizumi·Katharina Tinka Marquardt

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Abstract

The grain size of olivine influences mass and heat flux in Earth's upper mantle. We performed annealing experiments on synthetic olivine-pyroxene aggregates (6-13 vol.%) at 1-12 GPa and 1323-1793 K. Grain-size analysis via EBSD reveal an activation volume of $4.8 \times 10^{-6}\ \mathrm{m}^3/\mathrm{mol}$, matching silicon grain-boundary diffusion values. This suggests pressure-driven reduction in olivine growth rates may offset temperature effects at depth, enabling grain-size-sensitive creep at shallower mantle depths than previously modeled.

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Filippe Ferreira, Marcel Thielmann, Robert Farla, Sanae Koizumi, Katharina Tinka Marquardt. 2025-04-11. Pressure dependence of olivine grain growth at upper mantle conditions. https://arxiv.org/abs/2504.08425

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