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| Titel |
Effective buoyancy ratio: a new parameter for characterizing thermo-chemical mixing in the Earth's mantle |
| VerfasserIn |
A. Galsa, M. Herein, L. Lenkey, M. P. Farkas, G. Taller |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 6, no. 1 ; Nr. 6, no. 1 (2015-01-28), S.93-102 |
| Datensatznummer |
250115388
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| Publikation (Nr.) |
 copernicus.org/se-6-93-2015.pdf |
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| Zusammenfassung |
| Numerical modeling has been carried out in a 2-D cylindrical shell domain to
quantify the evolution of a primordial dense layer around the core–mantle
boundary. Effective buoyancy ratio, Beff was introduced to characterize
the evolution of the two-layer thermo-chemical convection in the Earth's
mantle. Beff decreases with time due to (1) warming of the compositionally
dense layer, (2) cooling of the overlying mantle, (3) eroding of the dense layer
through thermal convection in the overlying mantle and (4) diluting of the dense
layer through inner convection. When Beff reaches the instability point,
Beff = 1, effective thermo-chemical convection starts, and the mantle
will be mixed (Beff = 0) over a short time period. A parabolic relationship was
revealed between the initial density difference of the layers and the mixing
time. Morphology of large low-shear-velocity provinces and results
from seismic tomography and normal mode data suggest a value of
Beff ≥ 1 for the mantle. |
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