Constraints on the Earth’s inner core composition from high-pressure studies on Fe-Si-C alloys and compounds

Basic data for this project

Description

The composition and dynamics of the Earth’s inner core remain debated. Although it is widely accepted that it is comprised of a Fe-Ni alloy, the available seismological observations indicate, that it should additionally host around 4-7 wt% of light elements. Despite numerous studies over several decades, the nature of these elements remains unknown as none of the potential light elements candidates alone seems to match the available geophysical and geochemical constraints. The goal of this project is to use the experimental approach to determine the stability, elastic and plastic properties of Fe-Si-C alloys and compounds at conditions of the deep Earth’s interior. We will simulate these conditions employing resistively- and laser-heated diamond anvil cell and couple them with the state-of-the-art techniques on the third-generation synchrotron facilities. We will address the following questions: (1) Which phases in the iron-rich part of the Fe-Si-C ternary diagram are stable under conditions of the Earth’s core?, (2) what is the composition of the Fe-Si-C phase required to match the observed density-deficit in the Earth’s core?, (3) what are the dominant deformation mechanisms in these phases and can those mechanisms explain the observed anisotropy of the inner core? The answers to these questions will be used to refine a compositional model of the Earth’s inner core.