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| Titel |
Selfconsistent Formation of complex layered mantle flow with a Rough Core-Mantle Boundary |
| VerfasserIn |
Ulrich Hansen, Claudia Stein |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250112167
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| Publikation (Nr.) |
 EGU/EGU2015-12323.pdf |
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| Zusammenfassung |
| Thermal boundary layers play a key role for the dynamics of the Earth's
mantle. They mark the transition between the core and the mantle and, at
least locally and transiently, the transition between the upper and the
lower mantle at a depth of 670 km.
There is much evidence that these boundary layers do not resemble the
picture of a simple thermal boundary layer, as known from thermal
convection at high Rayleigh numbers. Especially the core-mantle boundary
(CMB) seems to be of complex structure, possible induced by
compositionally dense material.
Present models of mantle convection, aiming at simulating the complex
structure and dynamics of the CMB require several ad hoc assumptions.
Especially the density excess and the mass of compositionally distinct
material need to be assumed. Both conditions are critical for the
dynamics but hardly constrained.
We have developed models where the internal boundary as well as a
thermochemical CMB develop selfconsistently without the named ad hoc
assumptions. As a starting condition we assume that a chemically
stratified mantle, as resulting from fractional crystallization in an
early magma ocean, is heated by the hot core. Double diffusive
convection in material with strongly variable viscosity leads then to
layering and, in a later state to the formation of a rough lower
thermochemical boundary layer, displaying compositionally distinct piles. |
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