HR: 13:40h
AN: S33D-01    [Abstracts]
TI: Metastable superplumes and mantle compressibility
AU: * Tan, E
EM: tan2@gps.caltech.edu
AF: Seismological Laboratory, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 United States
AU: Gurnis, M
EM: gurnis@gps.caltech.edu
AF: Seismological Laboratory, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 United States
AB: Seismically, the African superplume is known to have a sharp lateral transition in Vs and an interface between seismic anomalies with high relief. Such structure is usually unstable in conventional thermo-chemical convection models. Using a compressible thermo-chemical convection model in which each material has a distinct equation of state, we find an expanded regime of metastable superplumes. In the preferred model, superplume material has a bulk modulus 6% higher and density 2.25% higher than ambient mantle. The inferred physical properties of the superplume are consistent with subducted oceanic crust (pyroxenite), a hypothesis that can satisfy seismological, geodynamical, mineralogical and geochemical constraints simultaneously.
DE: 1025 Composition of the mantle
DE: 1212 Earth's interior: composition and state (7207, 7208, 8105, 8124)
DE: 1213 Earth's interior: dynamics (1507, 7207, 7208, 8115, 8120)
DE: 7208 Mantle (1212, 1213, 8124)
DE: 8121 Dynamics: convection currents, and mantle plumes
SC: Seismology [S]
MN: Fall Meeting 2005