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| Titel |
Marangoni effect in metal-silicate self separation |
| VerfasserIn |
Stephane Labrosse, Hidenori Terasaki, Yanick Ricard |
| 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 |
250035487
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| Zusammenfassung |
| High pressure experiments of metal silicate mixture display a tendency for the molten metal
phase to percolate through the solid silicate matrix toward the coolest regions of the
sample. This simple observation carries important implications for processes leading to
formation of planetary cores and present day core-mantle interactions. For the percolation
to work, two ingredients are necessary, the classical wetting condition and a driving
force to compact the silicate matrix. In laboratory scale experiments, gravity is
negligible and the only available driving force is the interfacial tension, and in particular
its temperature dependence, the Marangoni effect. We developed a physical model to treat
numerically this problem within the framework of the compaction two-phase theory proposed
by Bercovici, Ricard et al. Experimental results can be used to tune several of the
unknown parameters in the numerical model and to test the theory. Both models and
experiments show that interfacial tension can trigger metal silicate differentiation at the
local scale, even in small planetesimals before gravity can act, and help global scale
core formation. In addition, at the bottom of the mantle, the large temperature gradient
can help core material to percolate upward. This process is much faster than the time
scale for changes in the mantle and a steady state calculation gives the height in the
mantle reached by the metal. The implications in terms of core-mantle electromagnetic
interactions will be considered. |
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