Formation, magmatic evolution and present-day structure of the CRUsts of Stagnant-LID planets

The low density of the Earth’s continental crust has been proposed to be at the origin of plate tectonics.

Physical studies on the continental crust have shown that its low density was acquired by differentiation of the crust and loss of dense mafic residues.

What is the composition and vertical structure of the crusts of the other terrestrial planets, which do not show plate tectonics? How did they form and what are the modifications they have undergone following their formations? Are they far from being of continental-type?

To answer these questions, I propose to study from a physical perspective the crust structure and the processes of crust formation and evolution on terrestrial planets other than Earth using innovative thermal, mechanical and dynamical models combined with new planetary observations.

Temperature is a crucial control variable as it dictates phase changes, buoyancy, mechanical properties and stress state.

In the crust and stagnant lithosphere of terrestrial planets, temperature is controlled by the distribution of heat producing elements.

Lithosphere cooling being the most likely cause of quakes on stagnant-lid planets, we propose to constrain the concentration and distribution of heat producing elements on Mars and the Moon by comparing recorded and predicted seismicity from thermal evolution models.

From these thermal evolution models, we will also evaluate the potential for planetary crust differentiation and evolution.

From magma ascent models, sensitive to crust density and mechanical state, combined with systematic in quantitative observations of volcanic structures and deposits on terrestrial planets, we will constrain the crust structure and thermal state.

Finally, we will develop new models of primitive crust formation in a stagnant lid regime of convection to evaluate the characteristics of primitive crusts on terrestrial bodies.