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03/10/16 Maylis Landeau (Johns Hopkins University)

Titre: Formation and dynamics of Earth's outer core (a l'ENS, amphi L)
When Oct 03, 2016
from 02:00 to 03:00
Contact Name Renaud Deguen
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Formation and dynamics of Earth's outer core

This seminar will investigate two major events in the structure and dynamics of Earth's outer core: giant impacts in the late stage of Earth formation and nucleation of Earth's inner core.

In the first part, we use fluid mechanics experiments to investigate the effect of giant impacts, such as the one that formed the Moon, on core stratification and metal-silicate equilibration. We obtain scaling laws on turbulent mixing after impacts that show that the stratification inferred from seismic data at the top of Earth's core can be explained as a vestige of the moon-forming giant impact. Our experiments suggest that metal-silicate equilibration following giant impacts extends to the protocore under extreme pressure-temperature.

In the second part, we examine the signature inner-core nucleation on the geodynamo. Energy considerations indicate that the power delivered to the present-day geodynamo comes mainly from the growth of the solid inner core. What did the geodynamo and the paleomagnetic field look like before inner-core nucleation? We address this question applying core energetics on convective dynamo simulations.

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