HR: 14:40h
AN: MR53A-05    [Abstracts]
TI: Fine Measurements of Geomaterials Thermoelastic Properties at Megabar Pressures
AU: * Guignot, N
EM: guignot@synchrotron-soleil.fr
AF: Synchrotron Soleil, L'Orme des Merisiers Saint-Aubin - BP 48, Gif-sur-Yvette, 91192, France
AU: Andrault, D
EM: d.andrault@opgc.univ-bpclermont.fr
AF: Laboratoire Magma et Volcans, 5 rue Kessler, Clermont-Ferrand, 63038, France
AU: Morard, G
EM: morard@esrf.fr
AF: ESRF, 6 rue Jules Horowitz BP 220, Grenoble, 38043, France
AU: Dewaele, A
EM: agnes.dewaele@cea.fr
AF: CEA/DPTA, BP12, Bruyeres le Chatel, 91680, France
AU: Roskosz, M
EM: Mathieu.Roskosz@univ-lille1.fr
AF: Laboratoire de Structure et Proprietes de l'Etat Solide, Universite des sciences et technologies de Lille, Villeneuve d'Ascq, 59655, France
AU: Loubeyre, P
EM: paul.loubeyre@cea.fr
AF: CEA/DPTA, BP12, Bruyeres le Chatel, 91680, France
AU: Bolfan-Casanova, N
EM: N.Bolfan@opgc.univ-bpclermont.fr
AF: Laboratoire Magma et Volcans, 5 rue Kessler, Clermont-Ferrand, 63038, France
AU: Mezouar, M
EM: mezouar@esrf.fr
AF: ESRF, 6 rue Jules Horowitz BP 220, Grenoble, 38043, France
AB: Accurately measuring the thermoelastic properties of geomaterials in the megabar pressure range is of first importance to correctly modelize the deep Earth. Thanks to recent developments and experimental improvements done on synchrotron radiation facilities, new standards in terms of level of detail and measurements accuracy have been achieved. In a recent work done on the post-perovskite phase MgSiO3 (N. Guignot et al., EPSL 256 (2007), 162-168), we could show that the thermal properties of that phase could be measured with a very high resolution, up to 140 GPa and 2500 K. Moreover, we could measure the post-perovskite phase elastic anisotropy with great details. The agreement between experiment and theory is observed to be very good. This study was a good opportunity to show the importance of not only accurate pressure scales and temperature measurements, but also correct equation of state mathematical formulations. We have recently performed a new experiment on iron up to 165 GPa and 3000 K at ESRF ID27 high pressure beamline. In order to accurately measure the P-V-T equation of state of epsilon-iron, MgO is added to the sample. NaCl is used as a thermal insulator. We see in that case that great care must be taken on a possible water contamination: a certain amount of iron can be oxidized and integrated in periclase, leading to wrong pressure measurements. Again, the data (approximately 200 P-V-T points) can be used to get the epsilon-iron P-V-T equation of state with a good resolution.
DE: 3909 Elasticity and anelasticity
DE: 3919 Equations of state
DE: 3949 Thermal expansivity
DE: 3954 X-ray, neutron, and electron spectroscopy and diffraction
DE: 3994 Instruments and techniques
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting