Time scales and heterogeneous structure in geodynamic earth models
Computer models of mantle convection constrained by the history of Cenozoic and Mesozoic plate motions explain some deep-mantle structural heterogeneity imaged by seismic tomography, especially those related to subduction. They also reveal a 150-million-year time scale for generating thermal heterogeneity in the mantle, comparable to the record of plate motion reconstructions, so that the problem of unknown initial conditions can be overcome. The pattern of lowermost mantle structure at the core-mantle boundary is controlled by subduction history, although seismic tomography reveals intense large-scale hot (low-velocity) upwelling features not explicitly predicted by the models.
Bunge
HP
H.-P. Bunge, Institut de Physique du Globe de Paris, Laboratoire de Sismologie, 4 place Jussieu, 75252 Paris Cedex 05, France. M. A. Richards, Department of Geology and Geophysics, University of California, Berkeley, CA 94720, USA. C. Lithgo.
Richards
MA
Lithgow-Bertelloni
C
Baumgardner
JR
Grand
SP
Romanowicz
BA