The effect of continental plates on convective stirring efficiency

• Applicant: Professor Dr. Henri Samuel
• Subject Area: Geophysics
• Term: from 2010 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 169617267

Significant progress has been made in the past years in understanding the dynamics of convective motions in the presence of continental and oceanic plates. Oceanic plates are recycled into the mantle and are characterized by a relatively strong heat flux, while continents are more insulating, lighter and therefore not subductable. The dichotomy between continents and oceans is likely to have a first order influence on mantle motions, thus also on the efficiency of convective stirring over billions of years. Understanding these processes is essential to interpret Earth surface geophysical and geochemical data. However, this effect has not been considered in previous studies that investigated mantle convective stirring efficiency. We therefore propose to study and to quantify systematically the influence of continental lids on convective stirring efficiency, primarily as a function of the Rayleigh number, the insulating effect of the lid, and its horizontal extent. We will conduct 2D and 3D numerical simulations of incompressible convection at infinite Prandtl number, in which continental lids with be modeled as lighter, rigid lids of variable extent, thickness and thermal conductivity. We will use various complementary techniques for studying stirring processes and to quantify their efficiency. In addition, we will derive simple laws to express stirring time as a function of the governing parameters and the wavelength of heterogeneity.

• DFG Programme: Research Grants
• International Connection: France