Evolution of rocky planets: insights from convection in soft materials
| Quand ? |
Le 08/01/2024, de 11:00 à 12:00 |
|---|---|
| Où ? | Salle des Thèses |
| Participants |
Anne Davaille |
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The cooling and evolution of a planet strongly depends on the convective regime prevailing in its mantle (e.g. the 2900 km-thick enveloppe of solid rocks under our feet on Earth). Geophysical data show that the planets and rocky satellites of our solar system undergo very different evolutions and present-day dynamics. But the conditions necessary for convection to generate plate tectonics and quasi-continuous resurfacing on Earth, episodic resurfacing on Venus, heat pipes on Io, or no resurfacing on Mars, remain strongly debated. The difficulty comes from the complexity of rocks rheology : ductile at high temperature and on long time-scale, brittle at low temperature and short time-scale. This « soft matter » behaviour can be recovered in the laboratory using hydrogels and aqueous colloidal dispersions. We therefore have investigated the characteristics of convection in those systems. They show a diversity of regimes, including the ones encountered in rocky mantles. Their physical understanding provides precious constraints on the dynamics of planetary interiors.