HR: 0830h
AN: T11C-0404    [PDF]
TI: Thermodynamic Properties Across Seismic Discontinuities Show Strong Variations due to Compositional Effects
AU: * Jacobs, M H
EM: jacobs@geo.uu.nl
AF: Inst. Earth Sciences, Vening Meinesz Research School for Geodynamics, Utrecht UNiversity, Budapestlaan 4, Utrecht, 3584 CD Netherlands
AU: de Jong, B H
EM: bernard@geo.uu.nl
AF: Inst. Earth Sciences, Vening Meinesz Research School for Geodynamics, Utrecht UNiversity, Budapestlaan 4, Utrecht, 3584 CD Netherlands
AU: van den Berg, A P
EM: berg@geo.uu.nl
AF: Inst. Earth Sciences, Vening Meinesz Research School for Geodynamics, Utrecht UNiversity, Budapestlaan 4, Utrecht, 3584 CD Netherlands
AB: Thermodynamic properties of solid solution phases change with pressure, temperature and composition. In regions involving several of such phases, the change of pressure and temperature leads to a change in their composition. For the $MgO-FeO-SiO_2$ system, we demonstrate that the values of specific properties may change up to a 100% due to compositional effects in the regions associated with the 410 km and 660 km seismic discontinuities. However such changes are negligible in the lower mantle. The Figures show two examples of large compositional effects on heat capacity and bulk modulus in the transition zone for a pyrolitic overall composition $(Mg_{0.9}Fe_{0.1})_2SiO_4$ without pyroxene
DE: 3939 Physical thermodynamics
DE: 5102 Acoustic properties
DE: 5134 Thermal properties
DE: 8124 Earth's interior--composition and state (old 8105)
DE: 8147 Planetary interiors (5430, 5724)
SC: Tectonophysics [T]
MN: 2003 Fall Meeting