Flexure of the Lithosphere Beneath the North Polar Cap of Mars: Implications for Ice Composition and Heat Flow

Abstract

AbstractThe geodynamical response of the lithosphere under stresses imposed by the geologically young north polar cap is one of the few clues we have to constrain both the polar cap composition and the present‐day thermal state of Mars. Here we combine radar data with a flexural loading model to self‐consistently estimate the density ( ) and real dielectric constant ( ) of the polar cap, and the elastic thickness of the lithosphere underneath ( ). Our results show that ranges from 920 to 1,520 kg m , is 2.75 (+0.40, 0.35), and is between 330 and 450 km. We determine a polar cap volume that is up to 30% larger than current estimates that all neglect lithospheric flexure. Our inferred compositions suggest that, for dust content larger than about 6 vol%, 10 vol% CO ice is mixed within the polar deposits, which has important implications for the climate evolution of Mars.