NSF East Asia and Pacific Summer Institute (EAPSI) for FY 2013 in Australia

Pigott Jeffrey S, Columbus OH

Investigators

Abstract

This action funds Jeffrey S. Pigott of The Ohio State University to conduct a research project in Geosciences during the summer of 2013 at Curtin University in Perth, WA, Australia. The project title is "Calculation of the Water Storage Capacity of Garnets in the Earth's Deep Interior." The host scientists are Professor Kate Wright and Professor Julian Gale. This study addresses the Earth's water budget by calculating the water storage capacity of garnet, a mineral found in the Earth's upper mantle (~60 km - 410 km depth) and transition zone (410 km - 660 km depth). Garnet accounts for as much as 40 percent of the rock volume at 500 km. The water storage capacity of garnet depends on the mechanism by which the crystal structure incorporates hydrogen and is also a function of pressure, temperature, and garnet composition. At low pressures, hydrogen can substitute for silicon in the garnet structure and has been termed the hydrogarnet substitution. It is likely that the hydrogarnet substitution becomes less energetically favored when compared to other mechanisms at greater depths due to pressure. This study calculates the energetics of different defect mechanisms to pressures equivalent to 660-km depth for garnets in the pyrope-almandine system. The disseminated results of this work will compliment experimental studies and can be used by geodynamicists, geochemists, mineral physicists, and seismologists that model and predict the state and evolution of the Earth's mantle. Broader impacts of an EAPSI fellowship include providing the Fellow a first-hand research experience outside the U.S.; an introduction to the science, science policy, and scientific infrastructure of the respective location; and an orientation to the society, culture and language. These activities meet the NSF goal to educate for international collaborations early in the career of its scientists, engineers, and educators, thus ensuring a globally aware U.S. scientific workforce. Furthermore, the Fellow plans to publish the results of this research in peer-reviewed journals and present at international conferences as well as departmental seminars and colloquia at both Curtin University and The Ohio State University.