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| Titel |
The influence of plate boundary motion on mantle planform and heat flux in viscously stratified convection models |
| VerfasserIn |
Julian Lowman, Scott King, Sean Trim |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250048905
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| Zusammenfassung |
| A number of studies examining the influence of plates on mantle convection have concluded
that planform and thermal structure are strongly influenced by the plate geometry.However,
studies that have modeled evolving plate geometries over periods greater than a mantle transit
time indicate that mantle planform may not correlate with plate geometry. To assess the
influence of plate boundary motion on mantle convection, we investigate convection in a
plane-layer geometry system featuring four polygon-shaped plates. Plate boundaries are
moved at specified velocities that are consistent with the velocities associated with the
convection driven flow in the system interior. Plate velocities are time-dependent and use a
force-balance method to ensure that the plate motion neither drives nor resists the
convection. The influence of the plate boundary motion on convection is compared in
models featuring viscosity profiles that increase by factors of 30, 90, 300 and 1000
across the lower mantle. The effective Rayleigh numbers of these systems is held
at a nearly constant value. We find that convection planform is sensitive to both
divergent and convergent plate boundary motion for a system featuring as much as a
90-fold contrast in viscosity between the upper and lower mantle. However, as the
viscosity stratification is increased the response of the convection planform to the
motion of divergent plate boundaries diminishes. In contrast, we find planform and
specifically plume positions respond to the motion of convergent plate boundaries
even when the lower mantle viscosity is 1000 times greater than the upper mantle
viscosity. |
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