Spin Crossover in Ferropericlase at High Pressure: A Seismologically Transparent Transition? | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

Twitter

Aller au compte twitter

  Spin Crossover in Ferropericlase at High Pressure: A Seismologically Transparent Transition?

Type de publication:

Journal Article

Source:

Science, Volume 331, Ticket 6013 (2011)

ISBN:

0036-8075

Numéro d'accès:

ISI:000285974000035

URL:

http://www.sciencemag.org/content/331/6013/64

Mots-clés:

Minéralogie, UMR 7154

Résumé:

Seismic discontinuities in Earth typically arise from structural, chemical, or temperature variations with increasing depth. The pressure-induced iron spin state transition in the lower mantle may influence seismic wave velocities by changing the elasticity of iron-bearing minerals, but no seismological evidence of an anomaly exists. Inelastic x-ray scattering measurements on (Mg0.83Fe0.17)O-ferropericlase at pressures across the spin transition show effects limited to the only shear moduli of the elastic tensor. This explains the absence of deviation in the aggregate seismic velocities and, thus, the lack of a one-dimensional seismic signature of the spin crossover. The spin state transition does, however, influence shear anisotropy of ferropericlase and should contribute to the seismic shear wave anisotropy of the lower mantle.

Notes:

Antonangeli, Daniele Siebert, Julien Aracne, Chantel M. Farber, Daniel L. Bosak, A. Hoesch, M. Krisch, M. Ryerson, Frederick J. Fiquet, Guillaume Badro, James