HR: 16:30h
AN: MR14A-03    [Abstracts]
TI: P-V-T equations of state of lower mantle minerals: Constraints on mantle composition models
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: 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: Zhang, L
EM: l.zhang@gl.ciw.edu
AF: Institute of Physics, Southwest Jiaotong University, Chengdu, 610031 China
AU: Frank, M
EM: T60MRF1@wpo.cso.niu.edu
AF: Department of Geology and Environmental Geosciences, Northern Illinois University, DeKalb, IL 60115 United States
AU: Corgne, A
EM: a.corgne@gl.ciw.edu
AF: Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road, NW, Washington, DC 20015 United States
AU: Wheeler, K
EM: k.wheeler@gl.ciw.edu
AF: Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road, NW, Washington, DC 20015 United States
AU: Wheeler, K
EM: k.wheeler@gl.ciw.edu
AF: Lamont Doherty Earth Observatory and Department of Earth and Environmental Sciences, Columbia University, Palisades, NY 10964 United States
AU: Meng, Y
EM: ymeng@hpcat.aps.anl.gov
AF: HPCAT & Carnegie Institution of Washington, APS, Arginne, IL 60439 United States
AB: Ferropericlase (Mg,Fe)O is likely a stable phase coexisting with silicate perovskite in the Earth's lower mantle. Determination of a reliable P-V-T equation-of-state of this phase is therefore crucial for developing compositional and mineralogical models of the Earth's interior. In this study, we report new compression data on ferropericlase up to 136 GPa, covering the entire pressure range of the lower mantle. The experiments were performed at the HPCAT 16-ID-B beamline (Advanced Photon Source), using monochromatic X-radiation and a CCD area detector. We used (Mg$_{0.6}$Fe$_{0.4}$)O as the starting material. The powdered sample was sandwiched between NaCl and a mixture of NaCl-Au in an externally heated high-temperature diamond anvil cell. The sample was annealed at each pressure increment by laser heating. High-quality diffraction data were collected up to 136 GPa. The same starting material was also studied up to 27 GPa and 2173 K in a multi-anvil apparatus by X-ray diffraction. A reliable P-V-T equation of state for (Mg$_{0.6}$Fe$_{0.4}$)O was developed by combining the two data sets. The new results, together with our recent P-V-T data for Al-bearing perovskite up to 105 GPa and 1000 K, provide solid density measurements for the two most important lower mantle minerals under simultaneous high pressure and temperature conditions. The new data are used to model the density profile of the lower mantle and provide tight constraints on its chemical composition.
DE: 8124 Earth's interior--composition and state (old 8105)
DE: 3630 Experimental mineralogy and petrology
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: 2004 AGU Fall Meeting