Séminaire du lundi 10 octobre 2011 à 10h30

Exploring Extra-Solar Planetary Interiors with Laser-Driven Shock Waves

Dylan K. SPAULDING (Département de Physique Théorique et Appliqué, C.E.A. Bruyères-le-Châtel)

IMPMC, Université P. et M. Curie, 4, Place Jussieu, 75005 Paris

Salle de Conférence / Salle 401

Tour 23

4ème étage

Couloir 22-23

Résumé

The physical and transport properties of silicate and oxide melts at extreme pressures and temperatures are critical for understanding early planetary evolution and the aftermath of late-stage giant impacts such as that believed to have formed the Moon. This presentation reports on a suite of laser-driven shock experiments on major mineral phases of significance to the terrestrial mantle and extra-solar rocky planets SiO2, MgO and MgSiO3. Equation of state measurements were carried out for MgO and MgSiO3 to 6.4 and 9.5 Mbar, respectively, constraining controversial predications for the ultra-high pressure melt curves. Experiments on amorphous and crystalline MgSiO3 starting materials show evidence of a liquid-liquid phase transition with a volume reduction of ~5-8% near 3.5 Mbar and over a range of temperature of at least 7000 K, suggesting the potential for unexpectedly complex chemistry in silicate liquids. Transport properties are extracted from time-resolved optical reflectivity data and imply that the distinction between silicate and metallic constituents are blurred in deep planetary interiors with potential implications for coupling across the present-day core-mantle boundary

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