HR: 0800h
AN: MR31A-0116    [Abstracts]
TI: Elasticity of Hot-Pressed Minerals of the Earth's Transition Zone Determined by Resonance Ultrasound Spectroscopy
AU: * Isaak, D
EM: disaak@apu.edu
AF: Institute of Geophysics & Planetary Physics, University of California, Los Angeles, CA 90095-1567
AU: Gwanmesia, G
EM: ggwanmes@desu.edu
AF: Physics and Pre-Engineering Department, Delaware State University, Dover, DE 19901
AU: Triplett, R
EM: talion@netzero.net
AF: Physics and Pre-Engineering Department, Delaware State University, Dover, DE 19901
AU: Fisher, E
EM: efisher@apu.edu
AF: Department of Mathematics and Physics, Azusa Pacific University, Azusa, CA 91702
AU: Falde, D
EM: lcwr4c00@aol.com
AF: Department of Mathematics and Physics, Azusa Pacific University, Azusa, CA 91702
AU: Wang, L
EM: lipwang@notes.cc.sunysb.edu
AF: The Mineral Physics Institute, Earth and Space Sciences Building, State University of New York, Stony Brook, NY 11794-2100
AB: Models showing how processes in Earth's interior influence conditions near the surface must be constrained by accurate laboratory data. Understanding the effect of structure, temperature, and pressure on elastic properties of minerals is of special interest to Earth scientists. Accordingly, we have initiated a collaborative project to accurately and precisely measure the elasticity of several transition zone mineral phases using resonant ultrasound spectroscopy (RUS) on hot-pressed polycrystalline aggregates of these minerals. To date, we have studied the elasticity of CaTiO₃ perovskite (density=4.02 g cm^-3) from room temperature to 500 K and Mg₂SiO₄ forsterite (density=3.227 g cm^-3) at ambient conditions. For CaTiO₃ perovskite, we find K_s=173.9 GPa, G=104.7 GPa, (∂ K_s/∂ T)_P=-0.0188 GPa K^-1, and (∂ G/∂ T)_P=-0.0175 GPa K^-1. With the exception of the (∂ K_s/∂ T)_P result, these values are consistent with those from elasticity studies using alternative techniques. At room temperature, we obtain K_s=129.4 GPa and G=80.9 GPa for Mg₂SiO₄ forsterite which are in excellent agreement with results from single-crystal studies. We confirm that the hot-pressed specimens exhibit isotropic elastic behavior; there is no evidence that texturing and preferred orientation adversely affect the elasticity data. The significance of these studies will be discussed. We also expect to report on new measurements of temperature dependences of elasticity for both forsterite and wadsleyite hot-pressed polycrystalline aggregates.
DE: 3621 Mantle processes (1038)
DE: 3909 Elasticity and anelasticity
DE: 3919 Equations of state
DE: 3939 Physical thermodynamics
SC: Mineral and Rock Physics [MR]
MN: Fall Meeting 2005