Core formation represents a pivotal event in the history of the Earth and other planetary bodies. A number of mechanisms have been proposed for how the core and mantle separate and interact; their validity, however, must be tested by direct experimental simulations which have not been previously possible. The investigator has been developing a new method to use nanoscale X-ray computed tomography (nanoXCT) to capture images of materials at high pressure. It is proposed to use this novel x-ray imaging technique to study how minute amounts of iron and silicate minerals interact at ultrahigh pressures and temperatures in order to shed light on the separation of Earth's rocky mantle from its iron-rich core. As a picture is worth a thousand words, x-ray imaging research is also easily accessible to students and to the broader public, and the visualization of how Earth's core and mantle materials interact presented in 3D movie format provides an attractive tool for education and outreach. In California, teaching Earth Science as part of the curriculum is only required in the 6th grade, so this is a critical time for young girls to develop an interest in science and a unique opportunity to engage all students in the fields of Geosciences. One of the main outreach activities is to develop a working partnership with a Girls' Middle School through the design of activities that will relate x-ray tomography to seismic tomography, which the students will already have been exposed to through the MARGINS program.
The goal of this CAREER proposal is to improve our understanding of the Earth's deep interior focusing on developing high resolution nanoscale x-ray computed tomography (nanoXCT) to visualize Earth's core-mantle interactions. NanoXCT represents a powerful non-destructive, nanoscale resolution 3D probe which when coupled with a diamond anvil cell enables imaging of multiple minerals and amorphous phases (including melts) which are synthesized under extreme conditions. NanoXCT will be used to determine the texture and shape of molten iron and solid silicate minerals as they respond to the same intense pressures and temperatures found deep in the Earth will provide a test for potential mechanisms of core formation. Measurements of the shape of the melt pockets and channels formed by the putative partial melt which may exist in the layer just above the core-mantle boundary will provide insight into this complex region. With the added third dimension, higher resolution, and extension to very high pressures and temperatures, nanoXCT provides exciting new imaging opportunities for many fields beyond Earth Sciences.
