Séminaire du lundi 19 novembre à 10H30

IMPMC, Université P. et M. Curie, 4, Place Jussieu, 75005 Paris
Salle de Conférence, 4ème étage, Tour 22-23, Salle 401

SOUND VELOCITIES OF EARTH’S DEEP MATERIALS

Motohiko MURAKAMI (Tohoku University, Sendai)

Résumé :

Average composition and structure of the Earth’s deep interior can be approached
by comparing observed seismic velocities to appropriate laboratory data collected for
candidate materials under relevant conditions. Precise knowledge of the elastic
properties of Earth’s deep materials under high-pressure condition is therefore
crucial for constructing the accurate mineralogical model of the Earth’s deep interior.
Recent technical advances in high-pressure Brillouin spectroscopic measurements
combined with diamond anvil cell apparatus (DAC) extended significantly the upper
pressure limit for acoustic measurements and also enable us to explore the sound
velocities under high-pressure and high-temperature conditions using infrared laser
heating technique. Here we present the recent progress of elastic wave velocity
measurements on Earth’s deep materials by Brillouin spectroscopy in a DAC in
conjunction with synchrotron X-ray diffraction technique under ultrahighpressures.
Based on the results we have recently obtained on mantle minerals and glass
materials, the mineralogy of deep mantle and the structure of the silicate melt at the
base of the mantle will be discussed.