HR: 0800h
AN: T41B-1207    [Abstracts]
TI: Equation of State of Aluminous H-bearing Stishovite to 60 GPa
AU: * Lakshtanov, D L
EM: lakshtan@uiuc.edu
AF: University of Illinois at Urbana-Champaign, 1301 W.Green st 245 NHB, Urbana, IL 61801 United States
AU: Vanpeteghem, C B
EM: carine@uiuc.edu
AF: University of Illinois at Urbana-Champaign, 1301 W.Green st 245 NHB, Urbana, IL 61801 United States
AU: Jackson, J M
EM: jmjackso@uiuc.edu
AF: University of Illinois at Urbana-Champaign, 1301 W.Green st 245 NHB, Urbana, IL 61801 United States
AU: Prakapenka, V B
EM: prakapenka@cars.uchicago.edu
AF: for Advanced Radiation Sources, The University of Chicago, 9700 S Cass Ave, Argonne, IL 60439-4832 United States
AU: Shen, G
EM: shen@cars.uchicago.edu
AF: for Advanced Radiation Sources, The University of Chicago, 9700 S Cass Ave, Argonne, IL 60439-4832 United States
AU: Litasov, K D
EM: klitasov@ganko.tohoku.ac.jp
AF: Institute of Mineralogy, Petrology and Economic Geology, Tohoku University, Tohoku University, Sendai, Sendai, 980-8578 Japan
AU: Ohtani, E
EM: ohtani@mail.tains.tohoku.ac.jp
AF: Institute of Mineralogy, Petrology and Economic Geology, Tohoku University, Tohoku University, Sendai, Sendai, 980-8578 Japan
AU: Sinogeikin, S V
EM: sinogeik@uiuc.edu
AF: University of Illinois at Urbana-Champaign, 1301 W.Green st 245 NHB, Urbana, IL 61801 United States
AU: Bass, J D
EM: jaybass@uiuc.edu
AF: University of Illinois at Urbana-Champaign, 1301 W.Green st 245 NHB, Urbana, IL 61801 United States
AB: The equation of state of water-bearing aluminous stishovite has become an important issue in relation to the both the properties of subducting slabs and also the transport and retention of water in the deep mantle. There were numerous studies on elasticity of stishovite, however most of them were performed on pure SiO$_{2}$ compositions, which is not representative of natural stishovites formed in MORB layer of subducting slabs. We performed elasticity measurements of SiO$_{2}$ stishovites with various Al$^{3+}$ and H$^{+}$ contents with Brillouin scattering and x-ray diffraction techniques at ambient and high pressures. We have determined the P-V equation of state of Al-rich H-bearing SiO$_{2}$ stishovite by x-ray powder diffraction at pressures up to 60 GPa using synchrotron radiation. The sample contained 1.8 %wt Al$_{2}$O$_{3}$ and about 450 ppm or more of H$^{+}$. This composition corresponds to stishovite that would coexist with aluminous iron-bearing Mg-silicate perovskite in a subducted slab. Our results indicate that Al$^{3+}$ and H$^{+}$ have a less pronounced effect on the elastic properties of stishovite than it was reported earlier. Our results suggest that Al and H are retained in stishovite under extreme P-T conditions and that stishovite is an agent for transporting water to the deepest lower mantle. Brillouin scattering measurements of acoustic velocities on stishovites with various chemical compositions will also be discussed.
DE: 3909 Elasticity and anelasticity
DE: 3919 Equations of state
DE: 3924 High-pressure behavior
DE: 3934 Optical, infrared, and Raman spectroscopy
DE: 3954 X ray, neutron, and electron spectroscopy and diffraction
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting