Depth of faulting and ancien theat flows in the Kuiper region of Mercury from lobate scarp topography

Abstract

Mercurian lobate scarp sare interpreted to be the surface expressions of thrust faults formed by planetary cooling and contraction, which deformed the crust downto the brittle–ductile transition (BDT) dep that the time of faulting. In this work we have used a for ward modeling procedure in order to analyze the relation be tweens carptopography and fault geometrie sand dep thsas sociated with a group of prominent lobate scarps (Santa Maria Rupes and twoun named scarps) located inthe Kuiper region of Mercury for which Earth-based radar altimetry is available. Also aback thrust associated with one of the lobate scarps has been included in this study. We have obtained best fits for depthsof faul ting between 30 and 39 km; the results are consistent with the previous results for o ther lobate scarps on Mercury. The so-derived fault depths have been used to calculate surface heat flows for the time of faulting, taking into account crustal heat source sand a heterogeneous surface temperature due to the variable in solation pattern. Deduced surface heat flow sare be tween 19 and 39m Wm-2 for the Kuiper region, and between 22 and 43 mWm-2 for Discovery Rupes. Both BDT depth sand heat flows are consistent with the predictions of thermal history models for the range of time relevant for scarp formation.