Compaction of a mushy inner core : the fate of liquid trapped by fast growth.
Abstract
Earth's inner core structure is still not yet well understood. Viscous flows due to external forces and convective instabilities have been thoroughly studied, but unsuccessful to explain all seismic features. We propose here to explore the effect of melts in the structure of the inner core on the overall dynamics.
Due to secular cooling, the Earth's core crystallizes at its center. The solidification of a liquid core that contains impurities lead to partial crystallization and the possibility of a partially molten inner core. The mush undergo compaction driven by density difference between liquid and solid, thus expelling liquid from the matrix by viscous deformation. Sumita et al. (1996) proposed the compaction of a simple 1D mush to estimate the amount of melt trapped in the center of the inner core, finding that the compaction process is efficient to expel most of the liquid. We expand here this study, focusing on variations of the growth history of the inner core and exploring the parameter space of inner core properties. We will discuss a scenario of short episode of rapid growth as proposed by Huguet et al. (2018) and its implications for the early dynamo.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMDI43B0022L
- Keywords:
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- 1507 Core processes;
- GEOMAGNETISM AND PALEOMAGNETISMDE: 1510 Dynamo: theories and simulations;
- GEOMAGNETISM AND PALEOMAGNETISMDE: 3924 High-pressure behavior;
- MINERAL PHYSICSDE: 7207 Core;
- SEISMOLOGY