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| Titel |
Exploring the range of 3D thermo-chemical variations possible in the Earth's lower mantle |
| VerfasserIn |
Christine Houser, Guy Masters |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250038220
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| Zusammenfassung |
| We have determined a suite of thermo-elastic parameters from the MgO-FeO-SiO2-Al2O3-CaO
system from recent experiments that are consistent with the 1D seismic structure of the Earth.
Using the sensitivities of temperature and chemistry to seismic shear and compressional
velocity and density derived from these thermo-elastic parameters, we use a tomographic
inversion to solve for the changes in temperature, mole fraction of perovskite, and
mole fraction of iron in the lower mantle. The data include a large compilation
of long-period travel times of S and P phases as well as normal mode splitting
measurements which provide excellent depth resolution and good lateral resolution
even in the lowermost mantle. The thermo-chemical models show that a majority
of the anomalous structure in the lower mantle can be explained by variations in
temperature. However, in the central Pacific, compositional variations are likely
present in the form of an increase in the mole fraction of iron and perovskite. We also
present a range of models of temperature as well as perovskite, iron, and calcium
content that fit the seismic data. These thermo-chemical models demonstrate that
long-period body wave data can be used not only to indicate, but also to quantify
variations in lower mantle temperatures, major element chemistry, and mineralogy. |
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