Acoustic attenuation of mantle minerals and aggregates

The knowledge of acoustic attenuation is of great importance for modelling the seismic response of a planet. Anelastic/visco-elastic properties are also central to model tidal dissipation.

Acoustic attenuation can be investigated by cyclic loading experiments probing the dynamic response of materials to an applied stress. So far, shear modulus attenuation was only obtainable by torsional forced-oscillation tests in gas vessel apparatus, and limited to ~0.3 GPa. This approach can be extended up to 8 GPa and up to 2000 K by implementing the method on a rotational Paris‐Edinburgh press (press recently developed at IMPMC), in combination with synchrotron x-ray diffraction and radiography. At first the case of anhydrous and melt-free minerals will be addressed, and then the effects of water inclusions will be taken into account. Measurements on aggregates will follow.

Combined with elasticity measurements (sound velocity and equation of state), acoustic attenuation measurements will allow establishing the visco-elastic and rheological models for planetary mantles needed to correctly constrain interior structures using seismic data, rotation, and tidal dissipation. Given the foreseen P-range of the experiments, such approach can be used for the mantles of the Moon and of Mercury at first, and then extended to the case of Mars.

Photo of ROTOPEC © Yann Le Godec