Silicon Abundance in the Earth's Core Constrained by a Multi-Technique Approach
Abstract
The presence of light elements alloyed to iron in the Earth's core is well established, and core formation models based on metal-silicate equilibration point at silicon as one of the major light element in the inner core. However, attempts to constrain silicon abundance on the basis of comparison of velocities and densities of iron and iron alloys at high pressure and high temperature with seismic observations, so far, did not provide a unique answer.
Here we will present sound velocity (compressional velocity VP and shear velocity VS) and density (ρ) measurements on Fe and Fe-Si alloys at high pressure and high temperature obtained by complementary use of x-ray diffraction, inelastic x-ray scattering and picosecond acoustics. These results, combined with previous experiments and calculations, allow a precise determination of the VP-ρ and VS-ρ relations for Fe and Fe-Si alloys, and consequently to address the effect of Si on the velocities in the Fe-FeSi system in the range of Si concentrations 0 to 9wt.%, applicable the Earth's core. Combined with further constraints coming from melting curve determinations, these results suggest that Si cannot be the only light element in the Earth's inner core.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMDI43B0020A
- Keywords:
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- 1507 Core processes;
- GEOMAGNETISM AND PALEOMAGNETISMDE: 1510 Dynamo: theories and simulations;
- GEOMAGNETISM AND PALEOMAGNETISMDE: 3924 High-pressure behavior;
- MINERAL PHYSICSDE: 7207 Core;
- SEISMOLOGY