Iron spin transition in Earth's mantle.
High-pressure Mössbauer spectroscopy on several compositions across the (Mg,Fe)O magnesiowüstite solid solution confirms that ferrous iron (Fe(2+)) undergoes a high-spin to low-spin transition at pressures and for compositions relevant to the bulk of the Earth's mantle. High-resolution x-ray diffraction measurements document a volume change of 4-5% across the pressure-induced spin transition, which is thus expected to cause seismological anomalies in the lower mantle. The spin transition can lead to dissociation of Fe-bearing phases such as magnesiowüstite, and it reveals an unexpected richness in mineral properties and phase equilibria for the Earth's deep interior.
Speziale
S
S
Department of Earth and Planetary Science, University of California, Berkeley, 94720, USA.
Milner
A
A
Lee
V E
VE
Clark
S M
SM
Pasternak
M P
MP
Jeanloz
R
R