The investigators continue to see an ever-widening frontier of discovery in the first principles study of mantle materials. In their last renewal, the team proposed a major new expansion in the scope of their research from the study of the physical properties of individual mantle phases, towards an understanding of the interaction among them through phase transitions and chemical exchange. This widening of focus from the mineralogical towards the petrological has been very successful, and has been essential for continuing progress in understanding the origin of mantle structure, its composition, and evolution.
The PIs now propose significant advances in the realm of application of first principles methods to mantle materials. This proposal is based on the firm foundations of past success: they have developed all the tools that are needed to accomplish these goals, and have already obtained encouraging results in all areas. The investigators expect that their research will make key contributions to understanding: 1) The origins of lateral heterogeneity in the mantle, through investigations of the physical properties of solid solutions, including the influence of the high-spin to low-spin transition in iron. 2) The interpretation of samples of possible lower mantle origin, via predictions of phase equilibria and element partitioning among coexisting mantle phases including those on the enstatite-corundum join and in the MgO-FeO-SiO2 system. 3) The amount of water in Earth's mantle, through predictions of hydrogen solubility in nominally anhydrous phases, investigations of the stability of hydrous phases, and predictions of electrical conductivity. Mentoring of young scientists will continue to be an important part of the broader impacts of this research, including training of students and post-docs within the research groups and broader education facilitated by VLab, the Virtual Laboratory for Earth and planetary materials, and CIDER, the Cooperative Institute for Deep Earth Research.
