The effects of size, configuration and distribution of continents on the efficiency of heat transport

The addition of continents to the surface of a planet alters its interior dynamics; understanding this alteration is critical to understanding the thermal evolution of the Earth. Specifically, the increase in temperature induced by continental insulation can be compensated by an increase in the heat loss through the overturn of the oceanic lithosphere, thus contradicting the predicted reduction of global heat loss due to presence of continents (e.g., Lenardic et al, 2005; Cooper et al, 2006; Lenardic et al, 2011). We reconfirm this counterintuitive result with three-dimensional simulations. In addition, we explore variations in the configuration of continents on the surface. Within simulations with equivalent continental coverage, but varying configuration, there is a competition between the lateral size of the blocks and the natural horizontal scale of the convection pattern which influences the stability of the models over time, and the efficiency of heat transport. Smaller continental blocks tend to induce a stable planform with upwellings permanently avoiding the blocks. However, in cases with larger continental blocks, the imposed scale is larger than the preferred scale of the convection pattern and upwellings are unable to avoid the blocks altogether. The dependency on stability and efficiency of heat transport within the Earth on continental coverage and configuration suggests continents can play a significant role in the Earth's heat budget and thermal history. Cooper, C.M., A. Lenardic, and L.-N. Moresi "Effects of continental insulation and the partioning of heat producing elements on the Earth's heat loss." Geophys. Res. Lett., 33 ,10.1029, 2006; Lenardic, A., C.M. Cooper, and L.-N. Moresi "A note on continents and the Earth's Urey ratio", Physics of the Earth and Planetary Interiors, 2011; Lenardic, A., L.-N. Moresi, A.M. Jellinek, and M. Manga "Continental insulation, mantle cooling, and the surface area of oceans and continents." Earth Planet. Sci. Lett., 234 ,317-333, 2005.