The melting curve of FeSi to 150 GPa: Implications for D"

Authors: O. T. Lord (University of Bristol) , M. J. Walter (University of Bristol) , D. P. Dobson (University College London) , L. Armstrong (Delft University of Technology) , S. M. Clark (Advanced Light Source, Lawrence Berkeley National Lab.) , A. Kleppe (Diamond Light Source)
Co-authored by industrial partner: No

Type: Conference Paper
Conference: Conference on Goldschmidt 2010 - Earth, Energy, and the Environment
Peer Reviewed: No

State: Published (Approved)
Published: January 2010

Abstract: FeSi has been suggested as a possible constituent of the Earth’s D" layer as a reaction product between the (Mg,Fe)SiO3 perovskite or post-perovskite of the lower mantle and the Fe alloy of the outer core [1]. FeSi may also occur as a result of exsolution from the outer core during secular cooling [2]. We have measured the melting curve of FeSi up to 150 GPa using the LH-DAC and standard methods described elsewhere [3]. We utilize discontinuities in the laser power vs. temperature function as our primary melting criterion, and have sucessfully coroborated our melting curve with multi- anvil experiments at 12 GPa. The resulting melting curve reaches 4000K at the CMB (see figure below). Based on a simple estimate of the adiabat throughout the D" layer, this result suggests that FeSi might be solid in the upper part of the D" layer, but is likely to be molten toward the base. Such melts are likely to have a density intermediate between the mantle and core, and would therefore pond at the CMB. Molten FeSi is expected to have seismic wave velocities significantly lower than PREM at these depths, making it a plausible component of the deep melts thought to result in the Ultra-Low Velocity Zones [4].

Subject Areas: Earth Science


Instruments: I15-Extreme Conditions

Added On: 07/02/2011 10:09

Discipline Tags:

Earth Sciences & Environment Geology Geophysics

Technical Tags:

Diffraction