NSF Award
0337012
In the proposed research, the nature and rates of diffusion of water dissolved within several mantle minerals (olivine, orthopyroxene, and magnesiowustite) will be investigated as well as the effects of dissolved water on chemical kinetics. In particular, it is planned to: 1) extend previous work correlating O-H bands in the infrared spectra of olivine and forsterite with hydrogen-intrinsic defect associates and investigate the rates of diffusion of these associates to gain insight into diffusion rates for silicon and magnesium defect species; 2) characterize the nature of hydrous defects in orthopyroxene and investigate rates of incorporation of hydrogen-intrinsic defect associates; 3) investigate the effects of hydrous defects in magnesiowustite on the interdiffusion of iron and magnesium. This research extends on past contributions by the PI in understanding the relations between microscale defects in minerals and their bulk behavior. It is particularly timely given the strong current emphasis in this area of study. The results of this work will improve our knowledge of defects in minerals and the role of dissolved water in defining internal defect structure in the major mantle minerals. These investigations will also extend our understanding of the nature and dynamics of the Earth's interior and the role of water in facilitating chemical and mechanical processes, notably intracrystalline diffusion and rheology. This research program will form the focus of the PhD research of a graduate student, who will take the major role in the experimental and analytical work, will present the research at scientific conferences, and will take in the lead in writing research papers on the individual research topics for scientific journals.
