HR: 14:16h
AN: MR23D-04    [Abstracts]
TI: Spin Transition and Equation of State of Ferropericlase at High Temperature: Implications for Density Model of the Lower Mantle
AU: * Fei, Y
EM: fei@gl.ciw.edu
AF: Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road, NW, Washington, DC 20015, United States
AU: Ricolleau, A
EM: aricolleau@gl.ciw.edu
AF: Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road, NW, Washington, DC 20015, United States
AU: Cottrell, E
EM: ecottrell@gl.ciw.edu
AF: National Museum of Natural History, Smithsonian Institution, P.O. Box 37012, NHB-119, Washington, DC 20013, United States
AU: Zhang, L
EM: l.zhang@gl.ciw.edu
AF: Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road, NW, Washington, DC 20015, United States
AU: Corgne, A
EM: acorgne@els.mq.edu.au
AF: Macquarie University, Department of Earth and Planetary Sciences, North Ryde, NSW, 2109, Australia
AU: Wang, Y
EM: ywang@ciw.edu
AF: Peking University, Department of Geology, Beijing, 100871, China
AU: Komabayashi, T
EM: tkomabayashi@ciw.edu
AF: Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road, NW, Washington, DC 20015, United States
AU: Sata, N
EM: sata@jamstec.go.jp
AF: Japan Agency for Marine-Earth Science and Technology, Institute for Research on Earth Evolution, Yokosuka, Kanagawa, Japan
AU: Prakapenka, V
EM: prakapenka@cars.uchicago.edu
AF: GSECARS, University of Chicago, 9700 S. Cass Ave, Argonne, IL 60439, United States
AU: Meng, Y
EM: ymeng@hpcat.aps.anl.gov
AF: HPCAT, Carnegie Institution of Washington, 9700 S. Cass Ave, Argonne, IL 60439, United States
AB: Iron-bearing lower mantle mineral, ferropericlase, undergoes an electronic transition of high-spin to low-spin in Fe²⁺ at high pressure. It has been documented that the spin transition causes a volume decrease and it occurs in the mantle pressure range at room temperature. In order to determine if the transition occurs in the Earth's lower mantle and understand its effect on mantle density profile, we have performed a series of compression experiments on (Mg_0.80Fe_0.20)O (fp20) and (Mg_0.61Fe_0.39)O (fp39) at high temperatures up to 3000 K. The high-PT experiments were performed at synchrotron facilities, using the externally-heated and laser-heated diamond-anvil cell techniques. Three sets of diffraction data of fp39 up to 80 GPa and 1000 K (external heating), 60 GPa and 3000 K (laser-heating), 100 GPa and 2400 K (laser-heating) were used to establish the P-V-T equation of state and determine the effect of temperature on the spin transition. Diffraction data of fp20 were also obtained up to 110 GPa and 2000 K to evaluate the compositional effect. The experimental data indicate that the spin transition pressure increases with increasing the iron content and temperature. For any reasonable mantle composition models, low-spin state ferropericlase is expected in the Earth's lower mantle. Our comprehensive P-V-T data of ferropericlase allow us to precisely evaluate the effect of the spin transition on the density profile of the lower mantle.
DE: 3611 Thermodynamics (0766, 1011, 8411)
DE: 3621 Mantle processes (1038)
DE: 3919 Equations of state
DE: 3924 High-pressure behavior
DE: 3954 X-ray, neutron, and electron spectroscopy and diffraction
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting