Geophysics of Iron in the Earth's Core

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Located nearly 3000 km below the crust, the core represents the most remote region within our planet. Seismology and geodynamics have provided detailed descriptions of the core and its central role in the Earth's evolution and its dynamic processes. Determining the high pressure-temperature behavior of iron and iron-rich compounds and alloys is an important but challenging area of research which is integral for gaining insight into the Earth's core. The PI proposes to conduct laboratory experiments that simulate the high pressures and temperatures that exist in the Earth's deep interior and measure the properties of iron-rich materials which can be dramatically altered at extreme conditions. The primary goal of the present research is thus to understand the Earth's core, which plays a central role in the magnetism, dynamic processes, and thermal evolution of our planet. The anticipated, high pressure-temperature data on iron and iron-rich compounds will be valuable to a wide variety of researchers involved in deep Earth studies (e.g. theoretical mineral physicists for improving their calculations, seismologists for interpretation of their observations, and geodynamicists for constraining their models). In addition, the technical advances will be useful to other experimentalists in the geosciences as well as fundamental and applied sciences.The central theme of this renewal proposal is to continue to improve our understanding of the high pressure-temperature shear properties and strength of iron and iron-rich compounds and alloys through a two-pronged approach, specifically by conducting both static and dynamic compression experiments. The first direction will build on the team's progress with diamond anvil cell measurements coupled with multiple synchrotron x-ray techniques to investigate the aggregate sound velocities and strength of iron and iron-rich compounds and alloys at high pressures and temperatures. The second approach is focused on reaching core conditions via laser-driven shock experiments and developing diagnostics to study the shear properties and dynamic behavior of iron and iron-rich compounds and alloys. The combination of the static and dynamic results will provide important information for helping to understand and interpret the complex seismic signatures in the Earth's core. The static and dynamic experimental measurements on the shear properties of Fe and Fe-rich compounds and alloys represent a valuable data set for many other deep Earth researchers. They provide comparisons for interpreting seismic observations of sound velocities in the core. Geodynamicists can potentially use the results for testing hypotheses on the geodynamo and crystallization/melting processes. The team's experimental data will also provide a useful constraint and comparison for theoretical mineral physics.