HR: 1340h
AN: MR43C-1517    [Abstracts]
TI: New Measurements on the Temperature Dependence of Elasticity of Polycrystalline Fe- Wadsleyite and Other Mantle Minerals
AU: * Isaak, D G
EM: disaak@apu.edu
AF: Institute of Geophysics and Planetary Physics, University of California, 405 Hilgard Ave., Los Angeles, CA 90095-1567, United States
AU: * Isaak, D G
EM: disaak@apu.edu
AF: Department of Mathematics and Physics, Azusa Pacific University, 901 E. Alosta Ave., Azusa, CA 91701-7000, United States
AU: Gwanmesia, G D
AF: Department of Physics and Pre-Engineering, Delaware State University, 1200 DuPont Highway, Dover, DE 19901, United States
AU: Triplett, R S
EM: talion@netzero.net
AF: Department of Physics and Pre-Engineering, Delaware State University, 1200 DuPont Highway, Dover, DE 19901, United States
AU: Davis, M G
EM: mgdavis@apu.edu
AF: Department of Mathematics and Physics, Azusa Pacific University, 901 E. Alosta Ave., Azusa, CA 91701-7000, United States
AU: Donahue, L K
EM: ldonahue@apu.edu
AF: Department of Mathematics and Physics, Azusa Pacific University, 901 E. Alosta Ave., Azusa, CA 91701-7000, United States
AU: Stafford, A M
EM: aams@apu.edu
AF: Department of Mathematics and Physics, Azusa Pacific University, 901 E. Alosta Ave., Azusa, CA 91701-7000, United States
AU: Stafford, S C
EM: saracstafford@gmail.com
AF: Department of Mathematics and Physics, Azusa Pacific University, 901 E. Alosta Ave., Azusa, CA 91701-7000, United States
AB: Understanding the composition and structure of Earth's mantle requires accurate and precise information about the elastic properties of candidate minerals and how these elastic properties are affected by temperature, pressure, and chemical variations. New elasticity data from room temperature to 640 K at ambient pressure for hot-pressed polycrystalline iron-bearing wadsleyite (Fe:Mg ~ 1:9) will be presented. These data were obtained using resonant ultrasound spectroscopy (RUS) on a Fe-wadsleyite shaped into a right-rectangular parallelepiped with dimensions of 1.965 mm x 1.667 mm x 1.416 mm. From analysis of 42 modal frequencies, the room temperature adiabatic bulk (K_S) and shear (G) moduli were found to be 171.3(0.7) GPa and 108.9(0.2) GPa, respectively, with numbers in parentheses indicating uncertainty. These results agree with room temperature values of K_S = 170(3) GPa and G = 108(2) GPa found in an earlier study on single-crystal Fe- wadsleyite using Brillouin spectroscopy, and they provide a better anchor point for investigating the temperature dependence of the elasticity of polycrystalline wadsleyite than values of K_S = 165.72(0.06) GPa and G = 105.43(0.02) GPa used by previous investigators. We carried out several temperature cycles from room temperature to 500 K (twice) and to 640 K (thrice) in order to determine the elastic properties at elevated temperature and to test reproducibility of the data. The temperature dependence of elastic moduli for Fe-bearing wadsleyite obtained from these experiments will be presented. We will also show recent results of high- temperature elasticity for other polycrystalline mantle minerals (forsterite, garnet).
DE: 3909 Elasticity and anelasticity
DE: 3919 Equations of state
DE: 8124 Earth's interior: composition and state (1212, 7207, 7208, 8105)
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting