Mantle convection controls the observed lateral variations in lithospheric thickness on present-day Mars

Sounding radar observations of the north polar layered deposits on Mars suggest an elastic lithosphere thickness of at least 300 km in that region, significantly larger than any prior estimate of lithospheric thickness on Mars. Previous studies interpreted this result as requiring either that Mars is significantly sub-chondritic in its abundance of radioactive elements, or alternatively that there are large lateral variations in lithospheric thickness. We find that the required depletion of radioactivity is geochemically unlikely. On the other hand, stagnant lid convection naturally produces factor of two or more lateral variations in both mantle heat flux and lithospheric thickness and is the preferred explanation for the polar elastic thickness measurement. Our mantle plume models, which have previously been shown to explain observations of present-day magma production on Mars, can also explain the new elastic thickness observations. Citation: Kiefer, W. S., and Q. Li (2009), Mantle convection controls the observed lateral variations in lithospheric thickness on present-day Mars, Geophys. Res. Lett., 36, L18203, doi:10.1029/2009GL039827.