HR: 0800h
AN: U41A-0736    [Abstracts]
TI: Mineral Physics Constraints on the Composition and Lateral Heterogeneity in the Lower Mantle
AU: * Li, B
EM: Baosheng.Li@sunysb.edu
AF: Mineral Physics Institute, SUNY Stony Brook, Stony Brook, NY 11794 United States
AU: Kung, J
EM: jkung@notes.cc.sunysb.edu
AF: Mineral Physics Institute, SUNY Stony Brook, Stony Brook, NY 11794 United States
AU: Zhang, J
EM: jzhang@lanl.gov
AF: LANSCE, Los Alamos National Laboratory, Los Alamos, NM 87545 United States
AB: New experimental results from a simultaneous determination of the pressure and temperature derivatives of the bulk and shear moduli and thermal expansivity of magnesium silicate perovskite at high pressure and high temperature enabled us to carry out an up-to-date modeling of both P and S wave velocities and density to the lower mantle depths to constrain the composition and temperature of the Earth's lower mantle. We found that a pyrolite composition along 1600K adiabatic geotherm can reproduce P and S wave velocities, Poisson' ratio, and density of PREM and AK135 reasonably well within experimental uncertainties. Discrepancies in composition and geotherm reported in previous studies could be attributed to the choice of thermoelastic properties of perovskite obtained from different experimental techniques. According to current modeling, the values of the dlnVs/dlnVp due to thermal effect are close to those observed by majority of seismic tomographic observation, ranging from 1.7 to 2.1 from the top to the lower part of the lower mantle. Other effects, including variations of perovskite and magnesiowustite proportions, Fe enrichment, as well as iron and magnesium partitioning between lower mantle phases on the lateral variation of S and P wave velocity change and density to shear wave scaling factor are also explored while searching for causes for anomalously high lateral heterogeneities observed in tomographic studies at the base of the lower mantle.
DE: 8130 Heat generation and transport
DE: 7207 Core and mantle
DE: 3919 Equations of state
DE: 1212 Earth's interior--composition and state (8105)
DE: 1507 Core processes (8115)
SC: Union [U]
MN: 2004 AGU Fall Meeting