Convection and transfers in a textured partially-molten planet from the magma ocean stage to present-day solid-state convection

Introduction

How and when plate tectonics (PT) developed on Earth, and why the Earth is currently the only rocky planet of the solar system with PT, are two of the main enigmas of Earth and Planetary Sciences. The evolution of a planet is conditioned by heat transfer in its most viscous envelope, the mantle.

Heat Transfer and Convection

This heat transfer is mostly due to convection, and strongly depends on the convective patterns, which in turn depend critically on mantle rheology. However, the link between rock rheology at small time- and length-scales, and mantle "effective" rheology at the long/large scales of mantle convection is still missing.

Meso-scale Structure

I propose that it resides in the meso-scale structure of the mantle and lithosphere that are acquired through convective motions and partial melting. Hence, deciphering the evolution of the Earth or any other planet requires describing and understanding the interplay between:

• "Texture" (i.e. material multi-scale organization)
• Rheology
• Two-phase flow
• Convection

Recent Findings

Our team recently showed that aqueous nanoparticle colloids, fluids commonly used by soft matter physicists, can reproduce planetary phenomena such as one-sided subduction and the two-phase flow dynamics of mid-ocean ridges.

Project Overview

Building on this, SOFT-PLANET will combine convection in these soft materials with state-of-the-art visualization techniques to relate:

• Surface morphology (including faults, wrinkle ridges, and volcanism)
• Lithospheric structure
• Internal flow patterns

We will characterize the development of texture and rheology from the nano-scale to the macro-scale of convection.

Goals of SOFT-PLANET

SOFT-PLANET will map the different regimes of convection that can develop and will derive a physical understanding of each. This new physical framework, together with geomorphology observations, will be used to decipher the current state of Venus and the divergent evolution of Venus, Mars, and the Earth.