The Earth's bulk composition is fundamental to the understanding of the formation and evolution of not only Earth but also other planets in our own and other solar systems. However, estimates of the composition of Earth's mantle, which comprises more than three-quarters of the Earth's volume and nearly two-thirds of its mass, remain controversial and elusive. The compositional makeup of this region is especially important for understanding chemical heterogeneity, which constrains deep structure and mixing and is crucial for inferring the thermo-chemical evolution of the Earth, from planet building and the magma ocean, to continental growth and the formation of the oceans and atmosphere. Investigations of natural rock assemblages that have compositions that include aluminum and calcium in addition to oxygen, silicon, magnesium and iron, have suggested that the upper and lower mantle are chemically distinct and that the transition zone may not only involve a change in mineral structure but may also mark a quasi-compositional boundary. There are several candidates for the 'natural' bulk Earth composition, and in this CAREER award she seeks to investigate the properties and signatures of these under extreme conditions. For example, two plausible lower-mantle compositions include one derived from the building blocks of the planet and another derived from parent bodies of ocean island basalts. Investigating the behavior of these compositions at high pressures and temperatures will test hypotheses on Earth's formation, elucidate the geochemistry of the deep mantle, and determine if mantle reservoirs of varying composition are seismologically identifiable.
The proposed mineral physics research uses extreme experimental conditions designed to reproduce and 'probe' the Earth's deep interior, and the exploration of such inaccessible regions is readily disseminated to the public through multimedia and graphical approaches. In particular, the PI proposes a novel way of teaching Earth science through the use of comics, in both printed and digital form. In doing so, the PI will be able to make topics such as Earth formation and evolution more accessible to students in the New Haven Public Schools System, as well as to the general public through online publication. Another integral part of this proposal is the training of graduate and undergraduate students in high-pressure mineral physics research through laser-heated diamond-anvil cell experiments at national synchrotron facilities. This training will contribute to the education of the next generation of independent researchers who will possess a thorough knowledge of high-pressure experiments that impact our understanding of the transfer of mass and energy within our planet. The proposed research will be carried out at facilities of all scales (PI's laboratory, departmental, national and international laboratories) and results will be disseminated broadly through teaching, community outreach, seminars, conferences and peer-reviewed publications.
