Thrust fault modeling and Late-Noachian lithospheric structure of the circum-Hellas region, Mars

The circum-Hellas area of Mars borders Hellas Planitia, a giant impact ∼4.0-4.2 Ga old making the deepest and broadest depression on Mars, and is characterized by a complex pattern of fracture sets, lobate scarps, grabens, and volcanic plains. The numerous lobate scarps in the circum-Hellas region mainly formed in the Late Noachian and, except Amenthes Rupes, have been scarcely studied. In this work, we study the mechanical behavior and thermal structure of the crust in the circum-Hellas region at the time of lobate scarp formation, through the modeling of the depth of faulting beneath several prominent lobate scarps. We obtain faulting depths between ∼13 and 38 km, depending on the lobate scarp and accounting for uncertainty. These results indicate low surface and mantle heat flows in Noachian to Early Hesperian times, in agreement with heat flow estimates derived from lithospheric strength for several regions of similar age on Mars. Also, faulting depth and associate heat flows are not dependent of the local crustal thickness, which supports a stratified crust in the circum-Hellas region, with heat-producing elements concentrated in an upper layer that is thinner than the whole crust.